Abstract:
A pressure controller for an artificial respirator according to this invention includes a control valve facing a gas passage between an inspiratory gas inlet and an inspiratory gas outlet, and an elastic biasing means for elastically biasing the control valve against a valve seat. When an adjustment manipulating member moves backward, even the pivotal motion of the adjustment manipulating member does not operate an adjustment operating member. When the adjustment manipulating member is pulled out, the pivotal motion of the adjustment manipulating member operates the adjustment operating member, thereby adjusting the elastic biasing force of the elastic biasing means. This invention provides a pressure controller for an artificial respirator capable of reliably preventing unnecessary operating of the adjustment operating member although the pivoting operation of the adjustment manipulating member is simple as a whole, and there is no possibility that the adjustment manipulating member and the like are broken.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of the Japanese Patent Application No. 2009-32371, entitled “Pressure Controller for Artificial Respirator and Artificial Respirator Using the Same,” filed on Feb. 16, 2009, the entire content of which is hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a pressure controller for use in an artificial respirator such as a resuscitator for supplying a gas to a patient requiring respiratory assistance, comprising a housing mechanism which has a first vent hole, a second vent hole and a third vent hole, and in which one of the first vent hole and the second vent hole is configured to be used as an inlet of an inspiratory gas and the other vent hole is configured to be used as an outlet of the inspiratory gas, a control valve placed in the housing mechanism to face a gas passage between the first vent hole and the second vent hole, elastic biasing means for elastically biasing the control valve against a valve seat formed in the housing mechanism, an adjustment operating member to be operated to adjust an elastic biasing force of the elastic biasing means, and an adjustment manipulating member to be pivoted to operate the adjustment operating member, wherein the control valve closes the third vent hole when a gas pressure in the gas passage is lower than a predetermined level, and the control valve opens the third vent hole such that a gas in the gas passage flows through the third vent hole when the gas pressure in the gas passage is higher than a predetermined level. The present invention also relates to an artificial respirator configured to control the gas pressure by the pressure controller as described above. 
     BACKGROUND OF THE INVENTION 
     A pressure controller for use in an artificial respirator for supplying a gas to a patient requiring respiratory assistance is disclosed in, e.g., U.S. Pat. No. 6,644,313B2. This pressure controller (to be referred to as “the pressure controller of patent reference” hereinafter) disclosed in U.S. Pat. No. 6,644,313B2 includes a housing mechanism having an inspiratory gas inlet, inspiratory gas outlet and third vent hole. The pressure controller of patent reference further includes: 
     (a) a control valve placed in a substantially cylindrical valve housing of the housing mechanism so as to face a gas passage between the inspiratory gas inlet and inspiratory gas outlet, 
     (b) a coil spring for elastically biasing the control valve against a valve seat formed in the valve housing, and 
     (c) an adjustment manipulating cap to be rotated to adjust the elastic biasing force of the coil spring. 
     The adjustment manipulating cap is screwed into a threaded portion formed on the outer circumferential surface of the tubular portion of the valve housing. Also, a gas discharge hole is formed as the third vent hole in the tubular portion of the valve housing. The control valve opens or closes in accordance with the pressure of a gas flowing through the gas passage, and the amount of screw-tightening or screw-loosening of the adjustment manipulating cap with respect to the threaded portion. Therefore, the gas flowing through the gas passage partially flows outside from the gas discharge hole in accordance with this open/closure state. In addition, to prevent an unnecessary pivotal motion of the adjustment manipulating cap, a pivotal-motion-preventing locking cap is detachably fitted on the cylindrical portion so as to cover the adjustment manipulating cap. 
     In the pressure controller of patent reference configured as described above, however, the adjustment manipulating cap must be covered with the pivotal-motion-preventing locking cap in order to prevent an unnecessary pivotal motion of the adjustment manipulating cap when, e.g., an operator or the like touches the cap with fingers. Also, to tighten or loosen the adjustment manipulating cap, the pivotal-motion-preventing locking cap must be removed from the adjustment manipulating cap. This increases the number of parts because the pivotal-motion-preventing locking cap is additionally necessary. In addition, the adjustment manipulating cap must be pivoted after the pivotal-motion-preventing locking cap is removed, and the pivotal-motion-preventing locking cap must be reattached after this pivotal motion. This complicates the pivoting operation of the adjustment manipulating cap as a whole. Also, the adjustment manipulating cap may unnecessarily pivot when removing and attaching the pivotal-motion-preventing locking cap. Furthermore, an operator may lose the pivotal-motion-preventing locking cap or may forget to attach it. Accordingly, the pressure controller of patent reference has the problem in reliably preventing an unnecessary pivotal motion of the adjustment manipulating cap. 
     SUMMARY OF THE INVENTION 
     The present invention can effectively correct the drawbacks of the pressure controller of patent reference as described above with a relatively simple arrangement. 
     According to the first aspect of the present invention, the present invention is a pressure controller for use in an artificial respirator such as a resuscitator for supplying a gas to a patient requiring respiration assistance, comprising a housing mechanism which has a first vent hole, a second vent hole and a third vent hole, and in which one of the first vent hole and the second vent hole is configured to be used as an inlet of an inspiratory gas and the other vent hole is configured to be used as an outlet of the inspiratory gas, a control valve placed in the housing mechanism to face a gas passage between the first vent hole and the second vent hole, elastic biasing means for elastically biasing the control valve against a valve seat formed in the housing mechanism, an adjustment operating member to be operated to adjust an elastic biasing force of the elastic biasing means, and an adjustment manipulating member to be pivoted to operate the adjustment operating member, wherein the control valve closes the third vent hole when a gas pressure in the gas passage is lower than a predetermined level, and the control valve opens the third vent hole such that a gas in the gas passage flows through the third vent hole when the gas pressure in the gas passage is higher than a predetermined level, characterized in that the adjustment operating member does not operate even when the adjustment manipulating member pivots by a pivoting operation of the adjustment manipulating member in a first state in which the adjustment manipulating member moves backward to the adjustment operating member, and the adjustment operating member operates to adjust the elastic biasing force of the elastic biasing means when the adjustment manipulating member pivots by the pivoting operation of the adjustment manipulating member in a second state in which the adjustment manipulating member is pulled out from the adjustment operating member. In this configuration of the first aspect (the second aspect to be described later is the same}, the adjustment manipulating member need not be covered with any pivotal motion preventing locking cap in order to prevent an unnecessary pivotal motion of the adjustment manipulating member. This simplifies the pivoting operation of the adjustment manipulating member as a whole. Also, there is no problem in reliably preventing unnecessary operating of the adjustment operating member. Furthermore, when the adjustment manipulating member moves backward to the adjustment operating member, the adjustment operating member does not operate even if the adjustment manipulating member pivots by the pivoting operation of the adjustment manipulating member. Accordingly, the adjustment manipulating member is not pivoted by a very large force unlike when the pivotal motion of the adjustment manipulating member is forcedly inhibited. This protects the adjustment manipulating member, adjustment operating member and the like from being broken. 
     According to the first mode of the first aspect of the present invention, a rotational torque required to pivot the adjustment manipulating member in the first state is preferably 4 to 25 cN*m (more preferably, 5 to 20 cN−m, and most preferably, 7 to 15 cN−m). In this configuration of the first mode of the first aspect (the fourth mode of the first aspect to be described later is the same), in the first state in which the adjustment manipulating member moves backward to the adjustment operating member and the adjustment operating member does not operate even when the adjustment manipulating member pivots by the pivoting operation of the adjustment manipulating member, the rotational torque required to pivot the adjustment manipulating member is relatively high. Accordingly, an operator such as a doctor has neither a sense of unease nor a sense of incompatibility when handling the adjustment manipulating member in the first state. 
     According to the second mode of the first aspect of the present invention, a rotational torque required to pivot the adjustment manipulating member in the second state is preferably 1.5 to 10 cN*m (more preferably, 2 to 8 cN−m, and most preferably, 3 to 6 cN−m). In this configuration of the second mode of the first aspect (the fifth mode of the first aspect to be described later is the same), in the second state in which the adjustment manipulating member is pulled out from the adjustment operating member and the adjustment operating member operates to adjust the elastic biasing force of the elastic biasing means when the adjustment manipulating member pivots by the pivoting operation of the adjustment manipulating member, the rotational torque required to pivot the adjustment manipulating member is high to some extent. Accordingly, an operator such as a doctor has neither a sense of unease nor a sense of incompatibility when handling the adjustment manipulating member in the second state. In addition, it is easy to accurately perform fine adjustment of the elastic biasing force of the elastic biasing means. 
     According to the third mode of the first aspect of the present invention, a ratio of the rotational torque required to pivot the adjustment manipulating member in the first state to the rotational torque required to pivot the adjustment manipulating member in the second state is preferably 1.2 to 5 (more preferably, 1.6 to 4, and most preferably, 2 to 3). According to the third mode of the first aspect described above, the rotational torque required to pivot the adjustment manipulating member in the first state is higher than that in the second state. In the first state, therefore, the adjustment manipulating member is not pivoted by an operation error. In addition, it is possible to well perform adjustment and fine adjustment of the adjustment manipulating member in the second state. 
     According to the fourth mode of the first aspect of the present invention, the present invention is preferably configured such that a first three-dimensional engaging portion is formed on a side of the housing mechanism, a second three-dimensional engaging portion configured to engage with the first three-dimensional engaging portion is formed on a side of the adjustment manipulating member, and engagement of the first three-dimensional engaging portion and the second three-dimensional engaging portion in the first state increases the rotational torque required to pivot the adjustment manipulating member. According to the fifth mode of the first aspect obtained by extending the fourth mode of the first aspect described above, the present invention is preferably configured such that engagement of the first three-dimensional engaging portion and the second three-dimensional engaging portion in the second state increases the rotational torque required to pivot the adjustment manipulating member. According to the sixth mode of the first aspect of the present invention obtained by extending the fourth mode of the first aspect described above, the first three-dimensional engaging portion is preferably a three-dimensional engaging portion formed into a substantially ring shape on an outer circumferential surface of the housing mechanism, and the second three-dimensional engaging portion comprises a plurality of three-dimensional engaging portions intermittently formed on an inner circumferential surface of the adjustment manipulating member. In this configuration of the sixth mode of the first aspect, the pivotal torque required to pivot the adjustment manipulating member with respect to a side of the housing mechanism can reliably be increased with a relatively simple arrangement. 
     According to the seventh mode of the first aspect, the present invention preferably comprises a top-surface member attached to a side of the housing mechanism such that the top-surface member does not move forward and backward in the direction in which the adjustment manipulating member is pulled out, and a conical coil spring interposed between the top-surface member and the adjustment manipulating member, wherein the adjustment manipulating member moving forward in the direction in which the adjustment manipulating member is pulled out is elastically biased in a direction of the backward motion by the conical coil spring. In this configuration of the seventh mode of the first aspect, in the second state in which the adjustment manipulating member is pulled out from the adjustment operating member, the adjustment manipulating member automatically moves backward by the elastic biasing force of the conical coil spring when an operator such as a doctor releases fingers from the adjustment manipulating member after pivoting the adjustment manipulating member with the fingers. This makes it possible to relatively easily perform the adjusting operation by the adjustment manipulating member. In addition, the conical coil spring is interposed between the top-surface member and adjustment manipulating member in order to automatically move the adjustment manipulating member backward. Accordingly, the accommodation space of the spring can be narrowed. 
     According to the eighth mode of the first aspect, the present invention is preferably configured such that the adjustment operating member comprises a first adjustment operating member arranged in the housing mechanism, and a second adjustment operating member arranged in the housing mechanism, the first adjustment operating member is configured to pivot by the pivoting operation of the adjustment manipulating member, thereby pivoting the second adjustment operating member, and the second adjustment operating member operates by the pivotal motion to adjust the elastic biasing force of the elastic biasing means. In this configuration of the eighth mode of the first aspect, the pivoting operation of the adjustment manipulating member pivots the first adjustment operating member, and the second adjustment operating member operates by this pivotal motion of the first adjustment operating member to adjust the elastic biasing force of the elastic biasing means. This makes it possible to reliably and smoothly perform the operation of adjusting the state in which the control valve is urged against the valve seat. According to the ninth mode of the first aspect of the present invention obtained by extending the eighth mode of the first aspect described above, the adjustment manipulating member is preferably an adjustment manipulating cap, and the adjustment manipulating cap is preferably substantially put on a head of the first adjustment operating member. In this configuration of the ninth mode of the first aspect, the adjustment manipulating member can easily and reliably be pivoted with respect to the first adjustment operating member. In addition, an interlocking/uninterlocking mechanism that transmits or does not transmit the pivotal motion of the adjustment manipulating member to the first adjustment operating member can simply and reliably be formed between the first adjustment operating member and adjustment manipulating member. 
     According to the 10th mode of the first aspect, the present invention is preferably configured such that the adjustment manipulating member comprises a first pivotal-motion-transmitting engaging portion, the adjustment operating member comprises a second pivotal-motion-transmitting engaging portion, and when the adjustment manipulating member is in a backward-motion position in which the adjustment manipulating member moves backward to the adjustment operating member, the first pivotal-motion-transmitting engaging portion of the adjustment manipulating member and the second pivotal-motion-transmitting engaging portion of the adjustment operating member are disengaged, and the adjustment operating member does not operate even when the adjustment manipulating member pivots by the pivoting operation of the adjustment manipulating member, and, when the adjustment manipulating member is pulled out from the backward-motion position with respect to the adjustment operating member, the first pivotal-motion-transmitting engaging portion and the second pivotal-motion-transmitting engaging portion engage with each other, thereby transmitting the pivoting operation of the adjustment manipulating member to the adjustment operating member and operating the adjustment operating member. In this configuration of the 10th mode of the first aspect, the arrangement of an interlocking/uninterlocking mechanism for achieving transmission or non-transmission of the pivotal motion of the adjustment manipulating member to the adjustment operating member can be simplified, and the operation can reliably be performed. According to the 11th mode of the first aspect of the present invention, an opening communicating with the third vent hole is preferably formed in a top-surface portion of the adjustment manipulating member. In this configuration of the 11th mode of the first aspect, an operator can control the number of times of respiration of a patient by intermittently closing the opening formed in the top-surface portion of the adjustment manipulating member with a finger or the like. In addition, even if the operator strongly presses the top-surface portion of the adjustment manipulating member when closing the opening with his or her finger, the adjustment manipulating member idles with respect to the adjustment operating member. Therefore, the adjustment operating member does not unnecessarily operate. 
     According to the second aspect of the present invention, the present invention relates to an artificial respirator configured to control a gas pressure by the pressure controller according to the first aspect described above. According to the first mode of the second aspect, the present invention preferably further comprises a face mask including a second inspiratory gas inlet to be connected to the inspiratory gas outlet of the pressure controller, wherein both the first vent hole and the second vent hole of the pressure controller are configured to be selectively connected to the second inspiratory gas inlet of the face mask, and one of the first vent hole and the second vent hole having connected to the second inspiratory gas inlet functions as the inspiratory gas outlet of the pressure controller, and the other vent hole functions as the inspiratory gas inlet of the pressure controller. In this configuration of the first mode of the second aspect, an operator of the pressure controller can use the pressure controller in two use states. Therefore, the operator can use the pressure controller in a use state convenient for him or her. According to the second mode of the second aspect of the present invention, an angle which an axis of the first vent hole of the pressure controller makes with an axis of the second vent hole is preferably 75° to 105° (more preferably, 80° to 100°, and most preferably, 85° to 95°). In this configuration of the second mode of the second aspect, the pressure controller can relatively conveniently be used in either of the two use states described above. 
     The above, and other, objects, features and advantages of this invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an embodiment in which the present invention is applied to a pressure controller of a T-piece resuscitator; 
         FIG. 2  is an exploded perspective view of the pressure controller shown in  FIG. 1 ; 
         FIG. 3  is a longitudinal sectional view of the pressure controller shown in  FIG. 1 ; 
         FIG. 4  is a longitudinal sectional view similar to  FIG. 3  when setting the PEEP in the pressure controller shown in  FIG. 1 ; 
         FIG. 5  is a sectional view taken along a line A-A in  FIG. 4 ; 
         FIG. 6  is a sectional view taken along a line B-B in  FIG. 4 ; 
         FIG. 7  is a sectional view taken along a line C-C in  FIG. 4 ; 
         FIG. 8  is a schematic perspective view of a first form of the use state of the T-piece resuscitator incorporating the pressure controller shown in  FIG. 1 ; 
         FIG. 9  is a schematic perspective view of a second farm of the use state of the T-piece resuscitator shown in  FIG. 8 , in which a resuscitator main body is not shown; 
         FIG. 10  is a perspective view when the T-piece resuscitator shown in  FIG. 8  is in the first use state, in which the resuscitator main body is not shown; 
         FIG. 11  is a longitudinal sectional view of the T-piece resuscitator shown in  FIG. 10 ; 
         FIG. 12  is a perspective view similar to  FIG. 8  when the T-piece resuscitator shown in  FIG. 8  is in the second use state; 
         FIG. 13  is a longitudinal sectional view of the T-piece resuscitator shown in  FIG. 12 ; 
         FIG. 14  is a perspective view of a face mask shown in  FIG. 10 ; 
         FIG. 15A  is a longitudinal sectional view showing the first procedure of the procedures of assembling the pressure controller shown in  FIG. 3  from the parts shown in  FIG. 2 ; 
         FIG. 15B  is a longitudinal sectional view showing the second procedure of the assembling procedures; 
         FIG. 15C  is a longitudinal sectional view showing the third procedure of the assembling procedures; 
         FIG. 15D  is a longitudinal sectional view showing the fourth procedure of the assembling procedures; 
         FIG. 15E  is a longitudinal sectional view showing the fifth procedure of the assembling procedures; and 
         FIG. 15F  is a longitudinal sectional view showing the sixth procedure of the assembling procedures. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment in which the present invention is applied to a pressure controller of a T-piece resuscitator will be explained below with reference to the accompanying drawings in the order of “1. Outline of Arrangement of Overall T-Piece Resuscitator”, “2. Arrangement of Pressure Controller”, “3. Procedures of Assembling Pressure Controller”, “4. Operation of Pressure Controller”, and “5. Method of Using T-Piece Resuscitator”. 
     1. Outline of Arrangement of Overall T-Piece Resuscitator as Shown in  FIG. 8 , a T-Piece Resuscitator Includes: 
     (a) a resuscitator main body  1 , 
     (b) a gas source (not shown) that supplies an inspiratory gas to the resuscitator main body  1  through a gas supply tube  2 , 
     (c) a pressure controller  4  to which the resuscitator main body  1  supplies the inspiratory gas through a gas supply tube  3 , and 
     (d) a face mask  5  attached to the pressure controller  4 . 
     The pressure controller  4  is also called a patient T-piece. A ring-like air bag  5   b  having a shape like a small ring buoy is attached to the lower surface of a mask main body  5   a  of the face mask  5 . The upper surface of the mask main body  5   a  has an air inlet/outlet pipe  5   c  to be used to let air in and let air out of the ring-like air bag  5   b  by using a syringe (in other words, a syringe having no needle attached; not shown) or the like. In addition, as shown in  FIG. 11 , a valve  7  to be opened or closed when letting air in or letting air out of the ring-like air bag  5   b  is formed between the air inlet/outlet pipe  5   c  and the upper surface of the ring-like air bag  5   b . A connecting pipe  8  is attached to the distal end portion of the gas supply tube  3 . 
     As shown in  FIG. 8 , a substantially tubular (e.g., a substantially cylindrical) inspiratory gas inlet  5   d  to be detachably connected to the pressure controller  4  is formed in a substantially central portion of the upper surface of the mask main body  5   a . Note that the face mask  5  may also be a cannula such as a tracheal cannula or nasal cannula. Reference numeral  6  denotes a flowmeter of the gas source. The flowmeter  6  is used to control the flow rate of the inspiratory gas to be supplied from the gas source to the resuscitator device main body  1  through the gas supply tube  2 . Note that in  FIG. 8 , the resuscitator main body  1  and its vicinity are reduced compared to other portions. 
     As shown in  FIG. 8 , the resuscitator main body  1  includes: 
     (e) a circuit pressure gauge  11  that displays the circuit pressure, 
     (f) a peak release pressure control knob  12  to be used to control the peak release pressure, and 
     (g) an inspiratory pressure control knob  13  to be used to control the inspiratory pressure. 
     The resuscitator main body  1  also has a gas supply hole  14  and gas discharge hole  15 . The terminal end portion of the gas supply tube  2  is connected to the gas supply hole  14 . The start end portion of the gas supply tube  3  is connected to the gas discharge hole  15 . 
     2. Arrangement of Pressure Controller 
     As shown in  FIGS. 1 to 4 , the pressure controller  4  includes a substantially T-shaped branch pipe (in other words, a manifold as a housing mechanism)  21  having a branch pipe portion  21   a  as a first pipe joint or first vent hole. The gas supply tube  3  is connected to the branch pipe portion  21   a  as shown in  FIGS. 8 ,  9  and  11 , or the inspiratory gas inlet  5   d  of the face mask  5  shown in  FIG. 14  is detachably attached to the branch pipe portion  21   a . When the male-type gas supply tube  3  is connected to the female-type branch pipe portion  21   a  (in other words, in the first use state of the T-piece resuscitator), the branch pipe portion  21   a  forms an inspiratory gas supply hole as an inspiratory gas inlet. When the male-type inspiratory gas inlet  5   d  is attached to the female-type branch pipe portion  21   a  {in other words, in the second use state of the T-piece resuscitator), the branch pipe portion  21   a  forms a gas inlet/outlet portion for a patient  22  as an inspiratory gas outlet. Furthermore, in the first use state as shown in  FIGS. 8 ,  9 ,  10  and  11 , the inspiratory gas inlet  5   d  of the face mask  5  shown in  FIG. 14  is detachably attached to another vent hole (the lower-half portion of the manifold  21  in the state shown in  FIG. 3 , i.e., a second pipe joint or second vent hole)  21   b  different from the branch pipe portion  21   a  of the manifold  21 . In the second use state, the gas supply tube  3  is connected to the vent hole  21   b  as shown in  FIGS. 12 and 13 . In the first use state, the second pipe joint  21   b  forms a gas inlet/outlet portion for the patient  22 . In the second use state, the second pipe joint  21   b  forms an inspiratory gas supply hole. 
     To make the T-piece resuscitator usable in both the first and second use states described above, conditions described in items (a) and (b) below are preferably met as shown in  FIG. 3 : 
     (a) the inner diameters of at least the distal end portions of the first pipe joint  21   a  and second pipe joint  21   b  are substantially the same, and 
     (b) the outer diameter of at least the distal end portion of that portion of the connecting pipe  8  which is connected to the manifold  21 , and the outer diameter of at least the distal end portion of the inspiratory gas inlet  5   d  are substantially the same. 
     Note that in the embodiment shown in the drawings, the inner diameter (in other words, the shape of the inner circumferential surface), the outer diameter (in other words, the shape of the outer circumferential surface) and the length of the first pipe joint  21   a  are respectively substantially the same as the inner diameter, outer diameter and length of the second pipe joint  21   b  as shown in  FIG. 3 . 
     As described above, the cylindrical inspiratory gas inlet  5   d  of the face mask  5  can selectively be fitted in and attached to the branch pipe portion  21   a  and second pipe joint  21   b  of the pressure controller  4 . This enables an operator  23  to use the pressure controller  4  in two use states, i.e., a longitudinal use state (in other words, the above-mentioned first use state) shown in  FIGS. 8 ,  9 ,  10  and  11 , and a lateral use state (in other words, the second use state) shown in  FIGS. 12  and  13 . When this point is taken into consideration, an angle  0   1  which a central line (in other words, an axis) L 2  of the manifold  21  makes with a central line L 2  of the branch pipe portion  21   a  is preferably about 90° as shown in  FIG. 3 . This similarly applies to an angle  0   2  which the central line {in other words, the axis) L i  of the lower-half portion  21   b  makes with the central line L 2  of the branch pipe portion  21   a . More specifically, each of the angles  0   1  and  0   2  is about 90° in the embodiment shown in the drawings. From the viewpoint of practicality, each of the angles  0   1  and  0   2  is preferably 75° to 105°, more preferably, 80° to 100°, and most preferably, 85° to 95°. 
     Parts described in items (c) to (j) below shown in  FIG. 2  are attached to the manifold  21  in advance: 
     (c) a positive end expiratory pressure (PEEP) control valve  24 , 
     (d) a return coil spring  25  as an elastic biasing means, 
     (e) a spring pressure control screw  26  as a second adjustment operating member or elevating adjustment operating member, 
     (f) a pivotal adjustment operating member  27  as a first adjustment operating member, 
     (g) an adjustment manipulating cap  28  as an adjustment manipulating member, 
     (h) a repulsion conical coil spring (in other words, a trapezoidal coil spring)  29  as an elastic biasing means, 
     (i) a top-surface member  31 , and 
     (j) an O-ring  32  and a substantially semi-circular stopper member  33 . 
     Note that in  FIG. 2 , the PEEP control valve  24 , spring pressure control screw  26 , pivotal adjustment operating member  27 , adjustment manipulating cap  28  and top-surface member  31  are viewed two ways, i.e., viewed obliquely from above and from below. As shown in  FIGS. 3 and 15A , a substantially ring-like groove  34  for fitting the O-ring  32  in it is formed by a pair of upper and lower substantially ring-like projections  35  and  36  in an upper-half portion  21   c  of the manifold  21 . Also, as shown in  FIG. 2 , a three-dimensional engaging portion  37  having a number of ridges vertically extending over substantially the entire length of the upper projection  35  is formed around substantially the entire circumferential surface of the projection  35 . Note that as shown in  FIGS. 2 and 7 , the three-dimensional engaging portion  37  may also be formed by sequentially arranging projections  37   a  having a substantially triangular sectional shape (in other words, recesses  37   b  having a substantially triangular sectional shape) as the above-mentioned ridges adjacent to each other. 
     As shown in  FIGS. 2 and 15A , a pair of attachment holes  41  facing each other at an angle of substantially 180° are formed in the substantially ring-like groove  34  of the manifold  21 . Note that each of the pair of attachment holes  41  is a through hole. A pair of stopper end portions  33   a  and  33   b  facing each other as stopper means of a stopper member  33  are inserted into the through holes  41  in order to attach the stopper member  33  to the manifold  21 . To this end, the pair of stopper end portions  33   a  and  33   b  protrude into an inner space  43  of the upper-half portion  21   c  of the manifold  21 . Also, as shown in  FIG. 3 , an isolation wall  44  isolates the inner space  43  of the upper-half portion  21   c  of the manifold  21  from the branch pipe  21   a  and lower-half portion  21   b  of the manifold  21  (except for a vent hole  42 }. A female screw  45  into which the spring pressure control screw  26  is to be screwed is formed on the inner circumferential surface of the lower portion of the upper-half portion  21   c.    
     As shown in  FIG. 2 , a pair of locking pawls  46   a  and  46   b  facing each other at an angle of substantially 180° project from the upper surface of the manifold  21 . The pair of locking pawls  46   a  and  46   b  is locked on the upper surface of a substantially ring-like portion  47  to be locked of the pivotal adjustment operating member  27 . Also, a pair of positioning portions  48   a  and  48   b  facing each other at an angle of substantially 180° project from the upper surface of the manifold  21 . Note that the pair of positioning portions  48   a  and  48   b  may make an angle of substantially 90° with the pair of locking pawls  46   a  and  46   b . The lower surface of the portion  47  to be locked comes in contact with the upper surfaces of the pair of positioning portions  48   a  and  48   b . Accordingly, the portion  47  to be locked is clamped between the pair of locking pawls  46   a  and  46   b  and the pair of positioning portions  48   a  and  48   b , and fixed to the manifold  21  thereby. 
     As shown in  FIG. 2 , the PEEP control valve  24  includes a substantially cap-shaped valve body  24   a , and a support shaft  24   b  integrally protruding from the upper surface of the valve body  24   a . A male screw  51  is formed on the outer circumferential surface of the spring pressure control screw  26 . Also, as shown in  FIGS. 2 and 15B , a substantially columnar hole  40  having a substantially vertically extending axis is formed in the lower-half portion of the spring pressure control screw  26 . Furthermore, a hole  50  that substantially vertically extends and communicates with the substantially columnar hole  40  is formed in the upper-half portion of the spring pressure control screw  26 . One half of the hole  50  is formed by a substantially semi-circular, large-diameter hole  50   a  having substantially the same diameter as that of the hole  40 . The other half of the hole  50  is formed by a substantially semi-circular, small-diameter hole  50   b.    
     As shown in  FIGS. 2 and 3 , a central hole  52  that may have a substantially circular cross section is formed to substantially vertically extend through the upper-half portion of the pivotal adjustment operating member  27 . The lower-half portion of the pivotal adjustment operating member  27  is formed by a substantially semi-tubular (e.g., a substantially semi-cylindrical) operating shaft  53 . A substantially ring-like engaging groove  54  is formed in the outer circumferential surface in a region including the upper end and its vicinity of the pivotal adjustment operating member  27 . Furthermore, a substantially disk-like, large-diameter portion  55  and an outer-circumference engaging portion  56  as a pivotal motion transmitting engaging portion formed adjacent to the lower surface of the large-diameter portion  55  are integrally formed in a middle portion in the vertical direction of the pivotal adjustment operating member  27 . Note that the outer-circumference engaging portion  56  has a shape obtained by cutting the outer circumferential surface of the large-diameter portion  55  into a polygon (an octagon in the embodiment shown in the drawings), etc. 
     As shown in  FIGS. 2 and 15D , an upper-half portion  57  of the adjustment manipulating cap  28  is formed into a substantially tubular (e.g., a substantially cylindrical) shape having an open upper end. A lower-half portion  58  of the adjustment manipulating cap  28  is formed into a substantially cylindrical shape having a diameter slightly smaller than that of the upper-half portion  57 . Between the upper-half portion  57  and lower-half portion  58 , an intermediate plate  59  is formed integrally with the upper-half portion  57  and lower-half portion  58 . In addition, in the outer circumferential surface of the upper-half portion  57 , a number of grooves  61  are intermittently formed at substantially equal intervals so as to extend substantially vertically so that the operator  23  can easily grasp the upper-half portion  57  with a finger  23   a . A plurality of {in the embodiment shown in the drawings, eight) slits  62  substantially vertically extending from the lower end to a region including the upper end and its vicinity are formed in the lower-half portion  58  of the adjustment manipulating cap  28 . 
     As shown in  FIGS. 2 ,  5  and  15 D, inner-circumference engaging portions  63  as pivotal motion transmitting engaging portions are integrally formed on the inner circumferential surface of the lower-half portion  58  of the adjustment manipulating cap  28 , such that each inner-circumference engaging portion  63  is formed between a pair of slits  62  adjacent to each other. Accordingly, a plurality of in the embodiment shown in the drawings, eight) inner-circumference engaging portions  63  are formed on the inner circumferential surface of the lower-half portion  58 . Each inner-circumference engaging portion  63  is formed as a substantially horizontally long bar so as to be able to face each flat surface of the outer-circumference engaging portion  56  of the pivotal adjustment operating member  27 . Furthermore, a plurality of (in the embodiment shown in the drawings, two) engaging projections  64  as substantially vertically extending three-dimensional engaging portions are integrally formed on the inner circumferential surface of the lower-half portion  58  so as to be adjacent to the lower sides of a plurality of (in the embodiment shown in the drawings, four) inner-circumference engaging portions  63 , e.g., every other inner-circumferential engaging portions  63 . 
     As shown in  FIGS. 2 and 15D , the plurality of slits  62  formed in the lower-half portion  58  of the adjustment manipulating cap  28  extend through the lower-half portion  58  of the adjustment manipulating cap  28  from the inner circumferential surface to the outer circumferential surface. Therefore, the slits  62  enable the circumferential portion of the lower-half portion  58  to readily elastically deform toward both the inner circumferential surface and outer circumferential surface with respect to the upper-half portion  57 . When performing plastic molding of the adjustment manipulating cap  28 , therefore, an inner metal mold is easily removed from the adjustment manipulating cap  28 . Also, when putting the adjustment manipulating cap  28  on the pivotal adjustment operating member  27 , the large-diameter portion  55  of the pivotal adjustment operating member  27  readily climbs over the inner-circumference engaging portions  63  of the adjustment manipulating cap  28  from the lower side to the upper side. 
     As shown in  FIG. 4 , the top-surface member  31  is formed into a substantially pot lid shape having an outer circumferential shape (in the embodiment shown in the drawings, a substantially disk shape) capable of accommodating the upper-half portion  57  of the adjustment manipulating cap  28 . A central hole  65  substantially corresponding to the central hole  52  of the pivotal adjustment operating member  27  is formed in the top-surface member  31 . Also, a plurality of (in the embodiment shown in the drawings, four) elastically deformable arms  66  are formed integrally with the top-surface member  31  so as to be adjacent to the central hole  65 . 
     3. Procedures of Assembling Pressure Controller 
     Examples of the procedures of assembling the pressure controller  4  by attaching the parts {except for the manifold  21 ) shown in  FIG. 2  to the manifold  21  as a housing mechanism will be explained below with reference to  FIGS. 15A to 15F . The procedures are as described in items {a) to (g) below. 
     (a) First, as shown in  FIG. 15A , the operating shaft  24   b  of the PEEP control valve  24  is relatively inserted into the return coil spring  25 . Then, as shown in  FIG. 15B , the valve body  24   a  of the PEEP control valve  24  is inserted into the inner space  43  of the upper-half portion  21   c  of the manifold  21  from an upper-end opening  71 , and placed on a valve seat  67  formed by the outer-circumferential portion of the vent hole  42 . 
     (b) Subsequently, as shown in  FIGS. 15B and 15C , the spring pressure control screw  26  is inserted into the inner space  43  of the upper-half portion  21   c  of the manifold  21  from the upper-end opening  71 . After that, the male screw  51  of the spring pressure control screw  26  is screwed into the female screw  45  of the manifold  21 . In this state, the upper-end portion of the return coil spring  25  is relatively inserted into the columnar hole  40  of the spring pressure control screw  26 . When the male screw  51  is kept screwed into the female screw  45 , the spring pressure control screw  26  moves down as it rotates, but an upward position regulating step  72  formed in the inner space  43  of the upper-half portion  21   c  of the manifold  21  regulates the lowermost position of the spring pressure control screw  26 . 
     (c) As shown in  FIG. 15C , the stopper member  33  is fitted in the ring-like groove  34  of the manifold  21  such that the pair of stopper end portions  33   a  and  33   b  of the stopper member  33  extend through the pair of attachment holes  41  from the outer circumferential surface of the manifold  21 , thereby attaching the stopper member  33  to the manifold  21 . In this state, the distal end portions of the pair of stopper end portions  33   a  and  33   b  protrude into the inner space  43  of the upper-half portion  21   c  of the manifold  21 . Accordingly, the end portions  33   a  and  33   b  regulate the uppermost position of the spring pressure control spring  26 . 
     (d) As shown in  FIG. 15C , the O-ring  32  is fitted in the ring-like groove  34  of the manifold  21 . The O-ring  32  prevents a gas in the inner space  43  of the upper-half portion  21   c  of the manifold  21  from flowing outside the manifold  21  from the pair of attachment holes  41 . 
     (e) As shown in  FIGS. 15C and 15D , the pivotal adjustment operating member  27  is inserted into the inner space  43  of the upper-half portion  21   c  from the upper-end opening  71  of the manifold  21 , and attached to the manifold  21  thereby. In this state, as described previously, the portion  47  to be locked of the adjustment operating member  27  is clamped between the pair of positioning portions  48   a  and  48   b  of the manifold  21  and the pair of locking pawls  46   a  and  46   b , and fixed to the manifold  21  thereby. Also, the operating shaft  53  of the adjustment operating member  27  is inserted into the large-diameter hole  52   a  of the spring pressure control screw  26 , and inserted into the coil spring  25  so as to surround the substantial half of the outer circumferential surface of the operating shaft  24   b  of the PEEP control valve  24 . 
     (f) As shown in  FIGS. 15D and 15E , the adjustment manipulating cap  28  is attached to the manifold  21  with the pivotal adjustment operating member  27  being interposed between them. When the adjustment manipulating cap  28  is put on the adjustment operating member  27 , the plurality of inner-circumference engaging portions  63  formed on the inner circumferential surface of the adjustment manipulating cap  28  move downward through the large-diameter portion  55  of the adjustment operating member  27 , and respectively face the plurality of outer-circumference engaging portions  56  of the adjustment operating member  27 . This prevents the adjustment manipulating cap  28  from being removed from the adjustment operating member  27 . In addition, the engaging projections  64  of the adjustment manipulating cap  28  three-dimensionally engage with the three-dimensional engaging portion  37  of the manifold  21  as shown in  FIG. 7 . 
     (g) As shown in  FIGS. 15E and 15F , the conical coil spring  29  and top-surface member  31  are sequentially accommodated in the upper-half portion  57  of the adjustment manipulating cap  28 . In this state, the conical coil spring  2   9  is sandwiched between the intermediate plate  59  of the adjustment manipulating cap  2   8  and the top-surface member  31  around the outer circumferential surface of the pivotal adjustment operating member  27 , and contracts to some extent. Also, the plurality of arms  66  of the top-surface member  31  once move away from the center of the central hole  65  in the top-surface member  31  to increase the size of the central hole  65 , and then returns to the original position. Therefore, the distal end portions of the arms  66  engage with the engaging groove  54  of the pivotal adjustment operating member  27 . This engagement prevents the removal of the top-surface member  31  from the adjustment operating member  27 . 
     The pressure controller  4  shown in  FIGS. 1 ,  3  and  4  can be assembled by performing the attaching operations as described in items (a) to (g) above. In the pressure controller  4  as described in item (f) above, the engaging projections  64  of the adjustment manipulating cap  28  three-dimensionally engage with the three-dimensional engaging portion  37  of the manifold  21  (see  FIG. 7 ). Accordingly, when compared to a structure in which a smooth first engaging portion of the adjustment manipulating cap  28  engages with a smooth second engaging portion of the manifold  21  which has substantially the same shape as that of the first engaging portion in a satisfactory fitting state, the magnitude of the rotational torque when pivoting the adjustment manipulating cap  28  with respect to the manifold  21  has a sufficiently large value as described in “4. Operation of Pressure Controller” below. 
     4. Operation of Pressure Controller 
     The operation in the first use state (see  FIGS. 8 to 11 ) of the pressure controller  4  will be explained below. Note that it is very obvious that substantially the same operation as that in the first use state is performed in the second use state (see  FIGS. 12 and 13 ) of the pressure controller  4 . 
     The gas supplied from the gas source through the gas supply tube  2 , resuscitator main body  1 , gas supply tube  3 , and connecting pipe  8  shown in  FIG. 8  is supplied into the manifold  21  from the first pipe joint (in other words, the inspiratory gas supply hole)  21   a  (in the second use state, the second pipe joint  21   b ) shown in  FIG. 3 . In this state, if the operator  23  such as a doctor closes the upper end of the central hole  52  of the pivotal adjustment operating member  27  with the finger  23   a  or the like, the gas does not flow outside from the central hole  52  whose upper end is closed with the finger  23   a  or the like even when the valve body  24   a  of the PEEP control valve  24  temporarily opens. Accordingly, the gas is supplied from the second pipe joint (in other words, the gas inlet/outlet portion for the patient  22 )  21   b  to the patient  22  via the face mask  5 . Also, when the operator  23  releases the finger  23   a  or the like from the upper end of the central hole  52 , the gas supplied from the gas source into the manifold  21  as described above presses the lower surface of the valve body  24   a  of the PEEP control valve  24 . In addition, the expiration from the patient  22  also presses the lower surface of the valve body  24   a  of the PEEP control valve  24  via the interior {in other words, a gas passage  73 } of the gas inlet/outlet portion  21   b  of the manifold  21 . This produces the possibility that the gas and expired air flow outside through the gap between the valve body  24   a  of the PEEP control valve  24  and the valve seat  67 , the inner space  43 , and the central hole (in other words, expiration exhaust hole}  52 . 
     That is, as shown in  FIG. 3 , the coil spring  25  as an elastic biasing means elastically presses the valve body  24   a  of the PEEP control valve  24  against the valve seat  67 . When the gas pressing force with which the gas from the gas source and the expired air from the patient  22  press the lower surface of the valve body  24   a  of the PEEP control valve  24  becomes larger than the elastic pressing force with which the coil spring  25  presses the upper surface of the valve body  24   a  of the PEEP control valve  24 , the valve body  24   a  of the PEEP control valve  24  floats {in other words, separates upward) from the valve seat  67  by an amount corresponding to the difference. Consequently, the gas and expired air flow outside through: 
     (a) the gap between the valve body  24   a  of the PEEP control valve  24  and the valve seat  67  of the manifold  21 , 
     (b) a vent hole  74  (see  FIG. 6 ) formed by the inner circumferential surface of the operating shaft  53  of the pivotal adjustment operating member  27  and the small-diameter hole  50   b  of the spring pressure control screw  26 , and 
     (c) the central hole  52  of the pivotal adjustment operating member  27 . 
     The magnitude of the elastic pressing force with which the coil spring  25  presses the upper surface of the valve body  24   a  of the PEEP control valve  24  can be adjusted by manipulating the adjustment manipulating cap  28 . This adjustment is performed as follows. First, the adjustment manipulating cap  28  shown in  FIG. 3  is raised from the manifold  21 , pivotal adjustment operating member  27 , top-surface member  31  and the like against the elastic biasing force of the conical coil spring  29 . As shown in  FIGS. 4 and 5 , this raise can be performed by the operator  23  with the fingers  23   a  until the inner-circumference engaging portions  63  of the adjustment manipulating cap  28  abut against the large-diameter portion  55  of the pivotal adjustment operating member  27 . In this state, the conical coil spring  29  elastically deforms into a substantially flat shape as shown in  FIG. 4 . Also, as shown in  FIGS. 4 and 5 , the inner-circumference engaging portions  63  of the adjustment manipulating cap  28  become able to engage with the outer-circumference engaging portion  56  of the pivotal adjustment operating member  27 . Therefore, by pivoting, clockwise or counterclockwise, the adjustment manipulating cap  28  which has been unable to engage with the adjustment operating member  27  in the pivoting direction, the pivotal adjustment operating member  27  (and in its turn the operating shaft  53 } pivots together with the adjustment manipulating cap  28 . As a consequence, the spring pressure control screw  26  also similarly pivots. Accordingly, the spring pressure control screw  26   
     having the male screw  51  screwed into the female screw  45  of the manifold  21  is further screw-tightened or screw-loosened (in other words, screwed upward or downward) with respect to the female screw  45 , thereby rising or falling the screw  26  with respect to the manifold  21 . Consequently, the coil spring  25  stretches as shown in  FIG. 4 , or contracts although not shown. Accordingly, the elastic pressing force with which the coil spring  25  presses the PEEP control valve
 
 24  against the valve seat  67  decreases or increases.
 
     Subsequently, when the operator  23  releases the fingers  23   a  or the like from the adjustment manipulating cap  28 , the adjustment manipulating cap  28  returns to the position shown in  FIG. 3  by the elastic biasing force of the conical coil spring  29 . In this state, the adjustment manipulating cap  28  of course similarly returns even if it is pushed downward by the fingers  23   a  or the like. Note that when closing the upper end of the opening  52  with the finger  23   a  or the like as shown in  FIG. 8  (in other words, in the state shown in FIG.  3 }, even if the upper end portions of the adjustment operating member  27 , top-surface member  31 , adjustment manipulating cap  28  and the like are strongly pushed downward, the inner-circumference engaging portions  63  and outer-circumference engaging portion  56  do not unnecessarily engage with each other. This prevents the pivotal adjustment operating member  27  from pivoting by an operation error. 
     As shown in  FIG. 7 , the four longitudinal engaging projections  64  of the adjustment manipulating cap  28  always engage with the substantially ring-like, three-dimensional engaging portion  37  of the manifold  21  (in other words, in both the normal use state shown in  FIG. 3  and the state shown in  FIG. 4  in which the PEEP control valve  24  is adjusted). Therefore, the three-dimensional engaging portion  37  forms a first torque increasing means, and the engaging projections  64  form a second torque increasing means. Since the first and second torque increasing means  37  and  64  cooperate, the operator  23  has neither a sense of unease nor a sense of incompatibility in the normal use state shown in  FIG. 3 , unlike when the adjustment manipulating cap  28  easily and unexpectedly pivots with respect to the manifold  21 . This enables the operator  23  to perform the normal use with a sense of security. Also, when adjusting the elastic pressing force with which the coil spring  25  presses the PEEP control valve  24  (see  FIG. 4 ), the operator  23  has neither a sense of unease nor a sense of incompatibility and has no difficulty in finely adjusting the elastic pressing force, unlike when the adjustment manipulating cap  28  easily and unexpectedly pivots with respect to the manifold  21 . Therefore, the operator  23  can perform adjustment and fine adjustment of the elastic pressing force with a sense of security. 
     In the normal use state shown in  FIG. 3 , a rotational torque required for the operator  23  to pivot the adjustment manipulating cap  28  with respect to the manifold  21  is about 10 cN*m in the embodiment shown in the drawings. From the viewpoint of practicality, this rotational torque is generally preferably 4 to 25 cN−m, more preferably, 5 to 20 cN−m, and most preferably, 7 to 15 cN−m. 
     On the other hand, in the adjustment state shown in  FIG. 4 , the above-mentioned rotational torque is about 4 cN−m in the embodiment shown in the drawings. Note that the rotational torque in the normal use state shown in  FIG. 3  is about 2.5 times that in the adjustment state shown in  FIG. 4  for the reason described below. That is, in the normal use state shown in  FIG. 3 , a portion having a length L 3  from the upper end of the slit  62  of the adjustment manipulating member  28  to a portion corresponding to the upper end of the three-dimensional engaging portion  37  of the manifold  21  functions as an effective spring portion of each of (a total of four) pressing leaf spring means  75 . Therefore, the pressing leaf spring means  75  press the three-dimensional engaging portion  37 . On the other hand, in the adjustment state shown in  FIG. 4 , a portion having a length L 4  from the upper end of the slit  62  of the adjustment manipulating member  28  to a portion corresponding to the upper end of the three-dimensional engaging portion  37  of the manifold  21  functions as an effective spring portion of each of (a total of four) pressing leaf spring means  75 . Therefore, the pressing leaf spring means  75  press the three-dimensional engaging portion  37 . Since the length L 4  is about 1.5 times the length L 3 , the effective spring length L 4  of the four pressing leaf spring means  75  in the adjustment state shown in  FIG. 4  is about 1.5 times the effective spring length L 3  of the four pressing leaf spring means  75  in the normal use state shown in  FIG. 3 . Accordingly, the pressing leaf spring means  75  having the effective spring length L 4  function as relatively soft leaf springs for the three-dimensional engaging portion  37 . Also, the pressing leaf spring means  75  having the effective spring length L 3  function as relatively hard leaf springs for the three-dimensional engaging portion  37 . 
     As described above, when the embodiment shown in the drawings is in the adjustment state shown in  FIG. 4 , the rotational torque required for the operator  23  to pivot the adjustment manipulating cap  28  with respect to the manifold  21  is about 4 cN−m. From the viewpoint of practicality, this rotational torque is generally preferably 1.5 to 10 cN−m, more preferably, 2 to 8 cN−m, and most preferably, 3 to 6 cN*m. 
     In the embodiment shown in the drawings, the ratio of the rotational torque in the normal use state shown in  FIG. 3  to that in the adjustment state shown in  FIG. 4  is about 2.5. From the viewpoint of practicality, this ratio is generally preferably 1.2 to 5, more preferably, 1.6 to 4, and most preferably, 2 to 3. 
     The rotational torque in the normal use state shown in  FIG. 3  is relatively high in order to allow the operator to readily notice that the operation of pivoting the adjustment manipulating cap  28  in the normal use state shown in  FIG. 3  is an operation error, and to prevent damage inflicted to the adjustment manipulating cap  28 , adjustment operating member  27  and the like when the adjustment manipulating cap  28  does not pivot even if a large force is applied. Also, the rotational torque in the adjustment state shown in  FIG. 4  is relatively low because if this rotational torque is too high, it becomes difficult to perform adjustment and fine adjustment by the pivoting operation of the adjustment manipulating cap  28 . 
     5. Method of Using T-Piece Resuscitator 
     An example of a method of using the T-piece resuscitator shown in  FIGS. 1 to 14  (in the first use state (see  FIGS. 8 to 11 ) of the pressure controller  4 ) will be explained below. This method is as described in items (a) to (i) below. Note that it is very obvious that even in the second use state {see  FIGS. 12 and 13 ) of the pressure controller  4 , the T-piece resuscitator can be used by substantially the same method as in the first use state described above. 
     (a) First, a test lung (not shown) is attached to the second pipe joint  21   b  forming the gas inlet/outlet portion for the patient  22 . This test lung can be an inflatable balloon. 
     (b) Then, the gas supply tube  2  shown in  FIG. 8  is connected to the resuscitator main body  1 . 
     (c) Subsequently, the flowmeter  6  shown in  FIG. 8  is adjusted in order to adjust the amount of gas flowing into the T-piece resuscitator from the above-mentioned gas source. 
     (d) As shown in  FIG. 8 , while the upper-end opening of the central hole  62  in the pivotal adjustment operating member  27 , which is open in a region including the top surface and its vicinity of the top-surface member  31 , is blocked (i.e., closed) with the finger (in the embodiment shown in the drawings, the thumb)  23   a  of the operator  23  such as a doctor, the peak circuit pressure is set by setting the peak release pressure control knob  12  at a selected value. 
     (e) After that, as shown in  FIG. 8 , while the upper-end opening of the central hole  52  of the pivotal adjustment operating member  27  is closed with the finger  23   a , the peak inspiratory pressure (in other words, PIP) is set by setting the inspiratory pressure control knob  13  at the peak inspiratory pressure. 
     (f) Then, the finger  23   a  is released from the upper-end opening of the central hole  52  in the pivotal adjustment operating member  27 , and the adjustment manipulating cap  28  in the state shown in  FIG. 3  is raised from the manifold  21  (and in its turn the pivotal adjustment operating member  27 ). This raise engages the inner-circumference engaging portions  63  of the adjustment manipulating cap  28  with the outer-circumference engaging portion  56  of the pivotal adjustment operating member  27 . In this step, the adjustment manipulating cap  28  need only be raised until it cannot be raised any more because the inner-circumference engaging portions  63  of the adjustment manipulating cap  28  abut against the head  55  of the pivotal adjustment operating member  27 . Subsequently, the adjustment manipulating cap  28  is pivoted clockwise or counterclockwise as needed with the fingers  23   a . Since this pivotal motion makes it possible to pivot the pivotal adjustment operating member  27  clockwise or counterclockwise as needed, the PEEP (i.e., the positive end expiratory pressure) can be set at a desired value. 
     (g) The test lung described above is detached from the gas inlet/outlet portion (in other words, the second pipe joint)  21   b  for the patient  22 , and the face mask  5  is attached to the gas inlet/outlet portion  21   b . The face mask  5  is then put on the mouth of the patient  22  as shown in  FIGS. 8 and 9 . 
     (h) As shown in  FIG. 8 , the number of times of respiration of the patient  22  is controlled by intermittently blocking the upper-end opening of the central hole  52  in the pivotal adjustment operating member  27  with the finger  23   a.    
     (i) When changing the peak inspiratory pressure described in item (e) above, the inspiratory pressure control knob  13  shown in  FIG. 8  must be controlled again. This can be done while ventilation is performed on the patient  22 , and the above-mentioned test lung need not be reattached. 
     Having described a specific preferred embodiment of this invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims. 
     For example, although the present invention is applied to the pressure controller  4  of the T-piece resuscitator device in the embodiment described above, the present invention is also applicable to a pressure controller of a resuscitator other than the T-piece resuscitator or a pressure controller of another artificial respirator. 
     Also, in the above-mentioned embodiment, the four longitudinal engaging projections  64  as the second three-dimensional engaging portions of the adjustment manipulating cap  28  engage with the substantially ring-like, three-dimensional engaging portion  37  as the first three-dimensional engaging portion of the manifold  21  even in the normal use state shown in  FIG. 3 . Therefore, the adjustment manipulating cap  28  does not easily and unexpectedly pivot with respect to the manifold  21 . However, it is also possible to prevent the first three-dimensional engaging portions  64  from engaging with the second three-dimensional engaging portion  37  as needed in the normal use state shown in  FIG. 3 . In this case, the adjustment manipulating cap  28  lightly idles with respect to the manifold  21  in the normal use state shown in  FIG. 3 . 
     In the above embodiment, the adjustment operating member is made up of the spring pressure control screw  26  and pivotal adjustment operating member  27 . However, the adjustment operating member may also be a single member obtained by integrally connecting the spring pressure control screw  26  and pivotal adjustment operating member  27 . In this case, the inner-circumference engaging portions  63  of the adjustment manipulating cap  28  and/or the outer-circumference engaging portion  56  of the pivotal adjustment operating member  27  need only be relatively lengthened in the axial direction. 
     In the above embodiment, the adjustment manipulating member  28  is formed into a substantially cap shape. However, the adjustment manipulating member  28  may also be formed into a substantially disk shape or plate shape. In this case, the substantially plate-like adjustment manipulating member  28  need only be pivotal and slidable in the axial direction with respect to the cylinder shaft of the pivotal adjustment operating member  27 . 
     In the above embodiment, the coil spring  25  is used as an elastic biasing means. However, the elastic biasing means may also be a leaf spring having a substantially wave shape such as a substantially S-shape, or a substantially columnar elastic member made of an elastic material such as rubber. In this case, the two end portions of the leaf spring or elastic column can be supported by the spring-receiving recess or spring-receiving upper surface of the control valve  24  and the spring-receiving recess of the spring pressure control screw  26 , respectively. One end portion of the elastic column may also be used as the control valve. 
     In the above embodiment, the second adjustment operating member (in other words, spring pressure control screw)  26  is screwed by the female screw (in other words, the feed screw)  45  formed on the inner circumferential surface of the upper-half portion  21   c  of the manifold  21 . However, the second adjustment operating member  26  may also be fed by a cam groove formed in the inner circumferential surface of the upper-half portion  21   c  of the manifold  21  and a cam follower formed on the second adjustment operating member  26 . 
     In the above embodiment, the projections  64  are formed as the second torque increasing means or second three-dimensional engaging portions on the adjustment manipulating cap  28 . However, the second torque increasing means or second three-dimensional engaging portions may also be recesses. 
     Furthermore, in the above embodiment, the first three-dimensional engaging portion  3   7  as the first torque increasing means is formed by a number of ridges formed on substantially the entire circumferential surface of the ring-like projection  35  of the upper-half portion  21   c  of the manifold  21 . In addition, the second three-dimensional engaging portions  64  as the second torque increasing means are formed by a plurality of, e.g., four engaging projections  64  intermittently formed on the inner circumferential surface of the lower-half portion  58  of the adjustment manipulating cap  28 . However, one or both of the first and second torque increasing means may also be surfaces on which a large number of regular or irregular bump-like projections are integrally formed. One or both of the first and second torque increasing means may also be simple rough surfaces having a relatively large friction coefficient. These rough surfaces may also be made of rubber. The outer circumferential surface of the ring-like projection  35  of the upper-half portion  21   c  of the manifold  21  may also be pressed into the inner circumferential surface of the lower-half portion  58  of the adjustment manipulating cap  28  by making the diameter of the inner circumferential surface of the lower-half portion  58  smaller than that of the outer circumferential surface of the ring-like projection  35  to some extent. In this case, one or both of the first and second torque increasing means need not be three-dimensional engaging portions.