Abstract:
The invention concerns a combination control for use in nasal cannula therapy, and includes a high flow, nasal cannula respiratory assistance ducted system, and a pressure relief valve having indicator structure, which typically includes a tubular body, a carrier slidable in the body, a plunger-indicator carried by the carrier, and a spring resisting carrier movement toward a cap on the body that defines an indicator window.

Description:
This application is a continuation-in-part of U.S. application Ser. No. 11/784,671, filed Apr. 10, 2007 now U.S. Pat. No. 8,001,966, which is a regular application converted from Provisional application Ser. No. 60/850,410, filed Oct. 10, 2006. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to nasal cannula therapy, and more particularly to improvements concerning fluid flow in nasal cannula therapy systems. 
     Nasal continuous positive airway pressure, NCPAP, is a used standard for administration of non-invasive positive airway pressure in the Neonate. Historically, Nasal Cannulae have been used at low flow rates (&lt;1.5 1 pm) during infant weaning from assisted ventilation, or for maintenance in the sub-acute phase of chronic lung disease. Difficulty in regulation of pressure, and concerns regarding the damaging effects of inadequately warmed and humidified oxygen delivery systems on nasal mucosa, precluded the use of these devices in the more acute phases of respiratory distress and at the higher liter flow rates that would have been required to generate the pressures necessary to provide for that particular disease process. Certain devices held the promise of improved humidification and warming of the cannula flow, but introduced the possible deleterious effect of unknown pressure propagation as well as reported bacteria contamination of the circuit. 
     Accordingly, there was concern about delivering pressures that were excessive and possibly damaging to the respiratory tract, sinuses, ear drum or GI tract. Mechanical ventilators used for assisted respirator having built in features for monitoring flow and pressures and are excessively expensive to supply and operate. 
     SUMMARY OF THE INVENTION 
     It is a major object of the invention to provide solutions to the described problems and difficulties. Basically, the invention is embodied in a combination control including monitoring for use in nasal cannula therapy, that comprises: 
     a) nasal cannula respiratory assistance ducted system, 
     b) the system including the following ii) means and at least one or both of the following i) means and iii) means,
         i) flow metering first means associated with said system ducting, upstream of the nasal cannula,   ii) safety pressure release and pressure level indicating second valve means also associated with said system ducting, downstream of the nasal cannula,   iii) flow metering third means associated with the system ducting, and downstream of the pop-off valve.       

     Another object of the invention includes provision, and in series sequence, of:
         i) an oxygen gas source,   ii) means receiving oxygen from said source, and air, for blending air, oxygen, and/or nitric oxide, in an output stream,   iii) a heater/humidifier to heat and humidify said stream,   iv) a nasal cannula to receive the heated and humidified stream, for administration to the infant or patient,   v) said i), ii) and iii) means as defined.
 
A further object includes provision of a by-pass outlet from the system for flow to the patient, downstream of said first means.
       

     Yet another object includes provision of a proportioning valve or other valve extending at a system outlet, and operating as said second means. 
     Another object of the present invention is to provide for requisite warmth and humidification of the air stream. The complications of inadvertent pressure propagation are avoided. The device allows for demand flow without using a conventional ventilator and subsequent costs. 
     Further objects include provision of 
     x 1 ) a tubular body having an end opening, and a step shoulder located in said body, 
     x 2 ) a pressure responsive carrier receive in and movable axially in the body, away from said step shoulder, 
     x 3 ) a plunger carried by the carrier, and having a stem extending axially toward the end opening, 
     x 4 ) a spring in the body acting to resist carrier axial displacement toward the end opening that would displace the plunger stem axially, 
     x 5 ) a cap on the body having at least one window via which axial displacement of the stem is visually observable. 
     These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: 
    
    
     
       DRAWING DESCRIPTION 
         FIG. 1  is a system diagram; 
         FIG. 2  is a system block diagram; 
         FIG. 3  is a perspective view showing actual elements of the system; 
         FIG. 4  is a section taken through a pressure relief flutter type valve, in a system; 
         FIG. 5  is a view showing system ducting, a pressure relief valve in series in the ducting; and a flow meter downstream of the pressure relief valve; 
         FIG. 6  is a view showing system ducting, a pressure relief valve in series in the ducting, and a flow meter upstream of cannula in the ducting; 
         FIG. 7  is a view like  FIG. 6 , but also showing an additional flow meter downstream of the pressure relief valve; 
         FIG. 8  is a section taken through a pressure relief-indication valve; 
         FIG. 9  is a section taken through a valve housing; 
         FIG. 10  is a section taken through an end cap that fits on the valve housing, for indicator view purposes; 
         FIG. 11  is a perspective view of the  FIG. 10  end cap; 
         FIG. 12  is a perspective view of an indicator plunger movable endwise in the housing and cap; 
         FIG. 13  is a section taken through a plunger carrier; 
         FIG. 14  is an end view of the carrier; and 
         FIG. 15  is a side elevation view of the carrier. 
     
    
    
     DETAILED DESCRIPTION 
     Referring first to  FIG. 1 , showing a preferred system, air supplied at  10 , and oxygen supplied at  100  enter a blending zone  12 , to be thoroughly mixed or blended. A control  11  to increase or decrease flows from the oxygen supply  100  is shown. The flowing mix passes to a flow meter at  16  via a warmer/humidifier  15 , which may consist of warm water into which the flow is injected to bubble up and continue flowing as at  17 , as warmed, humidified air/oxygen blend. Some of the flow passes to the small tubes or prongs  14  for supply to the infant&#39;s lungs. Some of that supply may variably leak to atmosphere, via the nostrils or expelled via the infant&#39;s mouth, for example along with flow expelled from the lungs, during breathing. Flow pressure supplied to the cannula is desirably below about 10 cm water pressure. The oxygen supply, as at hospital wall outlet  100 , is typically about 50 psi (3,154, cm/H 2 0). 
     Remnant air passes in duct  20   FIG. 4  to an outlet, such as a “pop-off” valve. The latter preferably takes the form of a proportioning valve, seen at  21   a  in  FIG. 4 , and having elastomeric flow control sections  21   b  that excessive air pressure forcibly spread apart, for example to suddenly discharge the flow when the pressure exceeds about 10 cm water pressure. See also arrow  23 , indicating discharge to atmosphere. Need for means to maintain pressure in the duct at or near 10 cm of water derives from the infant&#39;s lungs, which should not be subjected to excessive pressure. Such excessive pressure could arise as from closing of the infant&#39;s mouth or covering of its nostrils, or both, excessive pressure being variably transmitted to  21   a . Proportioning valve  21  or  21   a  is herein designated at times as a form of pressure relief “second means”. 
     The invention also contemplates provision and operating of flow metering third means, indicated at  28  in  FIGS. 1 and 5 , downstream of the cannula  14 , and downstream of the second means  21   a ; and/or provision and operation of flow metering first means, indicated at  32  in  FIG. 6 , in the ducting upstream of the nasal cannula  14 .  FIG. 7  shows use of both  28  and  32  in the system ducting. These elements typically have visible flow rate readouts, at the sides of transparent tubing  28   a  and  32   a , containing pistons  28   b  and  32   b  which shift position lengthwise in the tubing, as flow rates vary, to indicate such rates. Air flow pressure pushes such pistons against compression springs  28   c  and  32   c . If indicated flow at  28  shows loss of flow at  14 , the flow at  11  can be adjusted to compensate for the loss to atmosphere at  21   a , consistent with the infant&#39;s or patient&#39;s lungs. Such indicated rates, prior to adjustment, could for example be too low as a result of excessive leaking at the infant&#39;s nostrils or mouth. 
       FIG. 3  shows the ducting to include plastic tubing  40  forming a loop  41 , as a result of optional clasp  42  loosely grasping tubing portions  40   a  and  40   b  permitting relative slippage to contract or enlarge the loop, around the infant&#39;s head, for holding cannula prongs  14  in the nostrils. Note inclusion of the proportioning valve enclosure  46 , in series with the tubing. Fixture  47  connects the tubing to system ducting downstream of the heater humidifier  15 . 
       FIG. 2  is a block diagram of the system. 
     Referring now to the preferred valve of  FIGS. 8-15 , the following pressure indicating and pressure relief elements are shown, these being an improvement upon and substitute for the  FIG. 4  valve: 
     x 1 ) a tubular body  100  having an end opening  101 , and a step shoulder  102 , located in said body, 
     x 2 ) a pressure responsive carrier  103  received in and movable axially in that body, away from the step shoulder, 
     x 3 ) a plunger  104  carried by the carrier, and having a stem  104   b  extending axially toward said end opening, 
     x 4 ) a helically wound spring  106  in the body acting to resist carrier axial displacement toward said end opening that would displace the plunger stem axially, 
     x 5 ) a cap  107  on the body having at least one window  108  via which axial displacement of the stem is visually observable, due to excess air pressure exertion. 
     The following features are also of importance as to reliability, simplicity, and unusually effective operation. 
     Plunger  104  has a head  104   a  and a stem  104   b , received by and endwise assembled to the tubular carrier  103 , to be positioned by the carrier relative to the window  108 , for visibly indicating pressure “pop-off” or relief, even though such relief may not be audibly detectable due to very low pressure level. Ducting  103   a  on the carrier exterior passes pressurized flow toward window  108 , for exhausting via clearances to the exterior, after spring force is overcome by air pressure exerted against the closed end  103   c  of the carrier, via chamber  120 . 
     Also, the carrier has multiple speed peripheral guides  103   d  that protrude radially outwardly to easily slide against cylindrical bore  100   a  of the body  100 , during piston movement of the carrier with pressure exertion against carrier closed end  103   c . Guides  103   d  are annularly spaced apart, circularly about axis  14 , to allow flow of air past the carrier and via clearances to the escape window or windows  108 , as via clearance at  125  between the stem or shaft  104   b  of the plunger and the cylindrical bore  128  of the cap  107 . 
     Note that light weight, sensitive spring  106  is endwise compressed between plunger head  104   a  and the end shoulder  108   b  of a tubular stem  108   c  of the cap. That stem also assists centered guidance of travel of the carrier. 
     Ribbing  130  on the cap  107  extends laterally of the window or windows  108 , and protects the indicating end  104   c  of the plunger stem  104   b  as the stem is displaced into lateral alignment with the window. 
     Finally, it will be noted that the carrier and body form pressure receiving chamber  120  in communication with a tubular endwise projection  136  from the body, to receive air pressure exerted on the carrier via cannular tubing  140  fitting on  136 .