Blood sampling system

An apparatus for sampling blood through an intravenous or intraarterial tube which does not interfere with normal operation of an infusion operation or a direct pressure monitoring operation. A needleless sampling site at which fluid can be removed is connected to the tube. A chamber is provided which is connected to the tube such that fluid can be interchanged between the tube and the chamber. A plunger is provided for drawing the fluid from the tube into the chamber and for expelling the fluid from the chamber into the tube. In its normal position, the plunger blocks the interconnection between the tube and the chamber. When in its sampling position, the plunger creates a vacuum in the chamber causing the fluid in the tube to be aspirated into the chamber. The aspirating action causes fluid in the patient to be drawn up to the sampling site. An actuator, which can be operated by a single hand of a medical practitioner, imparts an appropriate feel to the system operation. A practitioner can carefully control the aspiration and expulsion operations of the system due to the resistance provided against the practitioner's hand movements and configuration of the body and the actuator means. The movement of the plunger is such that fluid is selectively drawn into and expelled from the chamber.

BACKGROUND 
1. The Field of the Invention 
This invention relates to medical devices used to repeatedly obtain blood 
samples from a patient by way of an indwelling infusion line. 
2. The Background Art 
In many cases, the condition of a patient requires that an 
intravenous/intraarterial tube or catheter be inserted into a blood 
vessel. The patient's blood vessel is connected by the tube to a source of 
fluid which provides fluid such as a medicament, and which is also 
connected to a pressure transducer which senses the pressure within the 
patient's blood vessel. 
In critical care situations, it is necessary to periodically obtain samples 
of the patient's blood. Importantly, each procedure carried out using a 
needle stick increases the likelihood of a health care worker being 
inadvertently stuck and thereby being infected from a contaminated needle. 
Rather than stick a patient with a needle each time blood must be drawn, 
it is preferred that blood be drawn through the tube already connected to 
the patient's blood vessel. Since the tube connected to the patient's 
blood vessel contains fluid other than blood, such as saline solution and 
some medication, it is necessary to draw the patient's blood up into the 
tube so that a blood sample can be obtained which is substantially 
unadulterated by the fluid which is being supplied to the tube by an 
external source. Once substantially unadulterated blood has been drawn up 
the tube to a sampling site, the blood sample can be collected into a 
sample container. 
Several devices have been proposed to draw blood up the tube connected to a 
patient's blood vessel to a sampling site. All of the proposed devices 
utilize a vacuum creating structure in communication with the tube to draw 
blood out of the patient's blood vessel up to, and past, a sampling site 
on the tube. Disadvantageously, many of the previously available devices 
require two-handed operation by a medical practitioner. Some of the 
previous devices utilize a conventional medical syringe to create the 
suction necessary to draw the blood up the tube. Such syringes are often 
unwieldy to use and their typical long, narrow dimensions makes them 
cumbersome. Many of the previously available devices are complicated and 
expensive. Moreover, some of the previously available devices include 
sharp bends in the fluid path and/or relatively long supplementary fluid 
paths both of which result in residual blood and fluid remaining in the 
fluid path which can cause problems such as clotting. 
In view of the forgoing, it would be an advance in the art to provide a 
blood sampling system which overcomes the difficulties and disadvantages 
present in the previously available devices. 
BRIEF SUMMARY AND OBJECTS OF THE INVENTION 
In view of the above described state of the art, the present invention 
seeks to realize the following objects and advantages. 
It is a primary object of the present invention to provide a patient fluid 
sampling system which is compact and convenient to operate. 
It is also an object of the present invention to provide a blood sampling 
system in communication with a patient's blood vessel which can aspirate 
blood up to a sampling site with the medical practitioner using not more 
than one hand. 
It is also an object of the present invention to provide an in-line blood 
sampling system which is reliable and inexpensive to manufacture. 
It is a further object of the present invention which minimizes the risk of 
infection due to operation thereof. 
It is a further object of the present invention to provide a blood sampling 
system which provides appropriate resistance and sensation for the medical 
practitioner using the system. 
These and other objects and advantages of the invention will become more 
fully apparent from the description and claims which follow, or may be 
learned by the practice of the invention. 
The present invention provides a system and method for sampling a body 
fluid through an infusion tube attached to a patient's body. The system is 
particularly adapted for use with a tube which is connected to a patient, 
such as patient's blood vessel, which is infusing a fluid into the vessel, 
for example from an infusion device and/or which is connected to a 
pressure transducer. When a blood sample is not being obtained, the 
sampling system allows an infusion operation and/or a direct pressure 
monitoring operation to be carried on unaffected. 
The preferred embodiments of the present invention include a sampling site 
connected to the tube at which fluid can be removed from the tube. The 
preferred sampling site is a needleless sampling site. A chamber, or means 
for forming a chamber, is provided. The chamber is preferably formed 
within a body fabricated from a clear plastic material suitable for 
medical applications. The tube connected to the patient has access to the 
chamber via a means for connecting the chamber to the tube such that fluid 
can be interchanged between the tube and the chamber. 
A plunger or plunger means is also provided. The plunger functions to alter 
the size of the chamber so that fluid is drawn from the tube into the 
chamber and also the fluid is expelled from the chamber into the tube. In 
some preferred embodiments, a means for actuating the plunger means is 
also provided. In its normal position, the plunger minimizes the size of 
the chamber. When actuated to a sampling position, the plunger creates a 
vacuum in the chamber causing any fluid in the tube to be aspirated into 
the chamber. The aspiration action causes fluid in the patient to be drawn 
up into a sampling site. The plunger is provided with a resilient tip 
which slidably engages the side of the chamber. 
The apparatus desirably provides operating characteristics which impart an 
appropriate feel to the system when it is handled and used by a medical 
practitioner. A medical practitioner can operate the aspiration and 
expulsion features of the system with only a single hand, if desired. 
Moreover, a medical practitioner can carefully control the aspiration and 
expulsion operations of the system due to the resistance provided against 
the practitioner's hand movements and the configuration of the apparatus. 
Advantageously, in one preferred embodiment of the inventions a 
perpendicularly to the chamber, passes through the apparatus body, and 
includes a means for receiving a portion of a user's hand. The actuator 
extends outwardly from the chamber only a short distance. A means is 
provided for translating the force applied by the user's hand in a 
direction substantially perpendicular to the chamber into movement of the 
plunger means such that fluid is selectively drawn into and expelled from 
the chamber. In other embodiments of the invention the plunger and the 
body are positioned within a housing so that as the body and the plunger 
cooperate to increase or decrease the size of the chamber while the 
overall length of the apparatus remains within the length of the housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Reference will now be made to the drawings wherein like structures will be 
provided with like reference designations. 
Reference will first be made to FIG. 1 which is a perspective view of a 
first presently preferred embodiment of the present invention. The blood 
sampling system illustrated in FIG. 1, generally indicated at 100, is 
preferably placed in-line with a catheter used for pressure sensing or 
in-line with an intravenous infusion device. The blood sampling system 100 
can be connected to other medical devices as known in the art and as 
explained herein. While the structures of the present invention are 
particularly adapted for use with sampling blood, it will be appreciated 
that the present invention can be used to sample other fluids, 
particularly biological fluids which are found in a patient's circulatory 
system, and this is to be understood whenever the term "blood" is used 
herein. 
The blood sampling system 100 comprises a body, generally indicated at 102, 
which includes a base 102A having two slots 102C used for securing the 
base 102A to another object. For example, the base 102A may receive a 
strap (not illustrated) which wraps around an adjacent object, such as a 
pole or a patient's arm. 
A chamber housing 102B is also part of the body 102. The base 102A and the 
chamber housing 102B are preferably fabricated as a single injection 
molded piece using a clear plastic material as known in the industry. All 
of the described components of the blood sampling system 100 are 
preferably fabricated from clear materials so that any bubbles present in 
the fluid can be observed. Desirably, the structure of the blood sampling 
system 100 of the present invention minimizes the creation of bubbles. A 
tube 104 leads to the patient (usually to an indwelling patient catheter 
represented in FIG. 5 at PC) and to a blood sampling site (represented 
generally at 156 in FIG. 5) at which blood will be collected. A tube 106 
leads to a source of fluid (FS in FIG. 5) and to a pressure transducer (PT 
in the FIG. 5). A cap 130 is provided on the top of the body 102. 
Reference will now also be made to FIG. 2 which is an exploded perspective 
view of the embodiment illustrated in FIG. 1. As can be seen in FIG. 2, 
two openings 166 are provided in the wall of the body 102. An actuator 122 
is configured to slidably rest within the openings 166 so that the 
actuator 122 passes through the body 102 (as also illustrated in FIG. 1). 
The actuator 122 is provided with an actuator slot 126. 
As shown best in FIG. 3, a plunger 128 is disposed within the body 102. The 
plunger 128 is generally cylindrical and is sized to substantially match 
the inner diameter of the body 102. A tip 114 is provided on the plunger 
128. The tip 114 is preferably fabricated from a resilient material as is 
available in the art. 
A fin 118 is provided on the upper side of the plunger 128. An inclined 
slot 120 is provided in the fin 118. A fin guide, shown in the cutaway 
portion of FIG. 2 at 131, is formed on the underside of the cap 130. The 
fin guide 131 is configured to receive the fin 118 therein as the fin 118 
moves as will be explained shortly. The thickness of the fin 118 is 
preferably selected so that it closely fits within the actuator slot 126. 
When the blood sampling system 100 is assembled, the fin 118 is held 
captive within the actuator slot 126 and a rod 124 is placed through bores 
125 provided in the actuator 122 and through the inclined slot 120. The 
rod 124 is preferably cylindrically shaped and is held in place in the 
bores 125 so that the rod 124 can slide along the inclined slot 120 to 
cause the movement of the plunger 128 within the body 102. It will be 
appreciated that the described structures are to be fabricated such that 
they withstand the pressures which will be encountered during use. 
As will be explained further shortly, the actuator 122 and the body 102 
together provide a structure which is comfortable, convenient, and 
efficient for a medical practitioner to operate for drawing blood up the 
tube 104 (FIG. 1) when desired to collect a blood sample. When it is 
desired to operate the blood sampling system 100, the medical practitioner 
pushes against the end of the actuator, most desirably with a thumb, 
finger, or palm of the hand, while also grasping the body 102 and/or the 
cap 130 with one or more fingers of the same hand. This advantageously 
allows efficient one-handed operation of the blood sampling system 100 in 
a manner not possible prior to the present invention. 
The cross sectional views of FIGS. 3 & 4 will be referred to next to 
further explain the structure of the blood sampling system 100 and the 
advantageous operation thereof. As seen in FIGS. 3 & 4, the cap 130 is 
provided with an inner rim 136 which engages a ridge 138 on the upper end 
of the body 102 to hold the cap 130 in place on the body 102. An inner lip 
132 extends from the lower side of the cap 130 and forms a recess with an 
outer lip 134 into which the wall of the chamber housing 102B is received. 
The plunger tip 114, shown in cross section, makes a slidable, fluid-tight 
engagement with the interior wall 102D of the body 102. The plunger tip 
114 is held in place on the plunger 128 by a retaining ring 116. 
The blood sampling system 100 is represented in its normal position in FIG. 
3. In the normal position, a substantially uninterrupted passageway 108 is 
formed between tube 104 and 106. In the normal position, normal fluid 
communication occurs between the patient (connected to tube 104) and the 
medical apparatus, such as a pressure transducer or intravenous fluid pump 
(connected to tube 106) as if the blood sampling system 100 was not 
present. Furthermore, the embodiments of the present invention avoids the 
problems which occur when the blood/fluid mixture is required to negotiate 
sharp bends or a long supplementary fluid path. Moreover, when in the 
normal position, the embodiments of the present invention described do not 
dampen the frequency response discerned by any pressure transducer being 
used. 
As known in the art, in order to obtain a blood sample, the tube 106 is 
blocked (for example clamped or stopped) and a vacuum is created to 
aspirate the fluid contained in the tube 104 into the body 102 causing the 
patient's blood to be drawn up into the tube 104 so that unadulterated 
blood reaches a sampling site. FIG. 5 provides a schematic diagram of the 
blood sampling system of the present invention which is connected to a 
stop cock 152 and a needleless blood sampling device 156 which functions 
as a sampling site. Optionally, in accordance with the present invention, 
the tube 106 may be left open (rather than being, clamped or stopped) and 
satisfactory aspiration of blood will occur. The needleless blood sampling 
device 156 works in cooperation with a sample container (not represented 
in FIG. 5), generally in the form of a syringe which can be readily 
attached and remove and which is configured to withdraw a blood sample 
from the needleless blood sampling device 156. In practice, the blood 
sampling system must provide unadulterated blood at the position of the 
needleless blood sampling device 156. That is, the blood must not be 
substantially mixed with any infused fluid or other fluid which may 
otherwise normally be present in the tube 104. 
Referring now to FIG. 3, to obtain a blood sample, a practitioner pushes 
the actuator in the direction of arrow 140. As the actuator is moved in 
the direction of arrow 140, the rod 124 is also moved. Since the 
combination of the plunger 116 and the fin 118 are held captive by the 
chamber housing 102B, the actuator slot 126, and the fin guide 131, as the 
rod 124 moves within the inclined slot 120 in the direction of arrow 140, 
the plunger 116 and the plunger tip 114 is moved upward in the direction 
of arrow 142 creating a chamber in communication with the passageway 108 
as represented in FIG. 4. 
As the actuator is moved by the medical practitioner, the structures 
described herein provide a suitable resistance to the pressure exerted by 
the medical practitioner. Such resistance provides the medical 
practitioner with a desirable feel and sensation when operating the blood 
sampling system and allows the practitioner to accurately control the rate 
at which the actuator 122 is moved. Moreover, as one end of the actuator 
122 is pushed by the practitioner, the other end of the actuator 122 
extends further from the body 102. In this way, the practitioner gains 
further control over the operation of the blood sampling system 100 by 
placing one portion of the practitioner's hand (e.g., a palm) on one end 
of the actuator 122 and another portion of the practitioner's hand (e.g., 
a middle finger) on the other end of the actuator. 
The described structures of the blood sampling system also provides that 
the plunger substantially remains in whatever position it is found at when 
the practitioner ceases to push on the actuator 122. Thus, advantageously, 
there is no need for an additional locking mechanism to lock the plunger 
in its normal position, or in any other position. Moreover, the volume of 
the chamber created when the plunger is in the position represented in 
FIG. 4 is great enough to accommodate enough blood and other fluid mixture 
so that the blood which is drawn up from the patient's blood vessel to the 
sampling site (the needleless blood sampling device 156 in FIG. 5) is 
substantially unadulterated. For example, the volume of the aspiration 
chamber of the embodiments described herein can be at least 10 cc for 
applications involving adults and at least 1 cc for applications involving 
neonates. Other volumes can also be used within the scope of the present 
invention. 
Referring again to FIG. 4, once the blood sample has been obtained, the 
practitioner pushes the actuator 122 in the direction of arrow 144 which 
causes the plunger 116 and the plunger tip 114 to move in the direction of 
arrow 146. Advantageously, the movement to expel is merely the reverse of 
the convenient movement to aspirate and the movement has the same 
desirable characteristics in both directions. The movement of the plunger 
116 expels the contents of the chamber back into the passageway 108 and 
the plunger assumes its previous position illustrated in FIG. 3. The blood 
sampling system 100 functions reliably for one hundred or more aspiration 
and expulsion cycles. 
It will be appreciated that the mating relationship between the bottom of 
the plunger tip 114 and the conical surface 102E of the chamber should be 
selected so that the contents of the chamber are expelled as completely as 
possible. While complete expulsion of the contents may not be practical in 
all circumstances, the residue which remains should be minimized so that 
clotting and other difficulties are minimized. When fabricating the 
conical surface 102E and the plunger tip 114 considerations such as the 
material and hardness of the plunger tip 114, matching or mismatching of 
the angles of the conical surface 102E and the surface of the plunger tip 
114, and the thickness of the plunger tip 114 material, should all be 
considered. It is within the scope of the present invention to fabricate 
the angle of the conical surface 102E and the angle of the plunger tip 
surface 114 so that the angles substantially match, so that the angles are 
substantially different, and so that the angles vary along the their 
surfaces. 
As can be seen best in FIG. 4, the embodiments of the present invention 
advantageously minimizes the possibility of contamination of the patient's 
blood and infused fluids with contaminants from the surrounding 
environment. Desirably, the wetted surfaces of the blood sampling system 
cannot come into contact with the medical practitioner during use. 
Airborne contamination is also minimized since air flow into the chamber 
is restricted and any airborne contaminants which are deposited on the 
inner wall of the body 102D are wiped by the plunger tip 114. It is also 
within the scope of the present invention to utilize a flexible covering 
over one or more portions of the blood sampling system 100 to completely 
isolate the wetted surfaces from airborne contaminants. 
FIG. 5 provides a schematic representation of an embodiment of the present 
invention with additional exemplary components which are commonly used in 
patient care applications. A blood sampling device 300 is represented with 
the tube 106 leading in the direction of arrow 164 to, for example, a 
pressure transducer PT and an infusion device acting as a fluid source FS. 
A clamp or stop cock structure 208 is preferably provided along the tube 
106 for imposition during aspiration of blood. As mentioned earlier, by 
proper selection of the components shown in FIG. 5, and their relative 
positions, the stop cock 208 structure need not be operated during the 
sampling of blood. A tube 104 leads to a fitting 150 to which a stop cock 
152 is preferably attached. 
A needleless blood sampling port 156 is provided with fittings 154 and 158. 
The needleless blood sampling port 156 is preferably one available in the 
art from Migada, Inc. under the trademark LAB-SITE but other structures 
can also be used as a sampling site. A fitting 160 connects to tubing 
which leads to the patient in the direction of arrow 162. It is to be 
understood that many additional and/or alternative structures can also be 
included in embodiments of the present invention. 
Reference will next be made to FIGS. 6-9 to describe the structure and 
operation of a second presently preferred embodiment of the present 
invention. FIG. 6 will be referred to next to provide an overall 
description of the structure and operation of the second presently 
preferred embodiment of the present invention generally indicated at 200. 
FIG. 6 is an exploded perspective view of the second presently preferred 
embodiment 200 illustrating the components thereof ready to be assembled. 
Illustrated in FIG. 6 is a shroud generally represented at 202. A plunger 
is also generally represented in FIG. 6 at 204 with a plunger tip being 
generally represented at 206 in FIG. 6. A body, generally represented at 
208, and an end cap, generally represented at 210, are also illustrated in 
FIG. 6. Further information regarding the structure, assembly, and the 
operation of these components will be provided hereafter. 
As explained earlier, the rigid components of the preferred embodiments are 
preferably fabricated from a clear plastic material suitable for medical 
applications. Desirably, the pertinent components are substantially 
visually transparent so that bubbles, clots, and other abnormalities 
within the fluid can be observed by a medical practitioner. 
The shroud 202 preferably comprises a cylindrical receptacle 213. It will 
be appreciated that the shroud 202 functions as a housing for the plunger 
204 and the body 208. Advantageously, as will be further explained 
shortly, the linear motion of the body 208 is limited to the length of the 
shroud 202. A concentric circle knoll 212 is preferably molded into the 
closed end of the shroud 202 as an indication to the medical practitioner 
where to place a thumb, finger, or palm during operation. An opening 214B 
is one of two openings (opening 214A is represented in FIGS. 7 and 8) 
which receive prongs 224A&B on the plunger 204. During assembly of the 
apparatus, it is preferred that the prongs 224A&B travel up tapered 
grooves, one of which is represented at 216, formed on the interior of the 
cylindrical receptacle 213 until the prongs 224A&B are received into their 
respective openings 214A&B. The plunger 204 is thus held in place in the 
interior of the cylindrical receptacle 213. 
Also provided in the cylindrical receptacle 213 are two slots 218A 
(illustrated in FIG. 7 & 218B) which receive the teeth 250A&B, 
respectively, in a locking engagement as will be explained further 
shortly. Also included in the cylindrical receptacle 213 are two cutouts, 
one shown in the perspective view of FIG. 6 at 220B and another at 220A in 
the cross sectional views of FIGS. 7 and 8. The cutouts 220A&B are 
dimensioned to receive the arms 252A&B included in the body 208 in a 
slidable fashion as will be explained in greater detail shortly. 
Also illustrated in FIG. 6 is an opening 222A. The opening 222A is one of 
two openings which receive the prongs 260A&B on the end cap 210 thus 
holding the end cap 210 in place on the shroud 202. A slotted plate 223 is 
provided on the cylindrical receptacle 213. The slotted plate 223 is used 
to attach the apparatus 200 to the patient via a strap (not illustrated in 
the figures) or to another structure. 
The plunger 204 fits within the cylindrical receptacle 213 of the shroud 
202. The diameter of a cylindrical base 232 is selected so that when the 
plunger 204 is held within the cylindrical receptacle 213 a gap exists 
between the circumference of the cylindrical base 232 and the interior of 
the cylindrical receptacle 213. The gap is best seen in the cross 
sectional views of FIG. 8 and is provided to receive a cylindrical vessel 
246 included in the body 208. 
As shown best in FIG. 6, four legs 226A&B and 230A&B extend perpendicularly 
from the cylindrical base 232 with each of the legs 226A&B and 230A&B 
preferably being oriented at right angles to each other. The legs 226A&B 
are provided with the two prongs 224A&B on the end of tines 224C&D which 
flex and allow prongs 224A&B to move as the plunger 204 is inserted into 
the cylindrical body 213 and engage the openings 214A&B. The legs 230A&B 
are each provided with a post 228A&B. The posts 228A&B each engage the 
interior surface of the cylindrical receptacle 213. The posts 228A&B 
function to further hold the plunger 204 in place and maintain the gap 
between the legs 226A&B and 230A&B and the interior of the cylindrical 
receptacle 213. A retaining disc 234 is provided on the plunger 204 to 
hold a plunger tip 206 in place thereon. 
The plunger tip 206 is preferably fabricated from a resilient material, for 
example those materials from which syringe plunger tips are fabricated in 
the industry. A groove 236 is provided on the interior of the plunger tip 
206 into which the retaining disc 234 is received. As seen best in the 
cross sectional views of FIGS. 7 and 8, the groove 236 and retaining disc 
234 hold the plunger tip 206 against the base 232. Also as seen best in 
FIGS. 7 and 8, the plunger tip 206 is provided with a first wiper 239 and 
a second wiper 238 which are particularly configured to slidably engage 
the interior surface 246A of the cylindrical vessel 246. The function of 
the plunger tip 206 will be further discussed later. 
Referring again to FIG. 6, the body 208 includes the cylindrical vessel 246 
and perpendicularly extending arms 252A&B. The arms 252A&B can preferably 
be molded as part of the cylindrical vessel 246. Each of the arms 252A&B 
includes passageways 256A&B, respectively, each of which communicate with 
the interior of the cylindrical vessel 246 as seen best in the cross 
sectional view of FIGS. 7 and 8. At the ends of each of the passageways 
256A&B are tubing bores 254A&B, respectively, which receive tubing 
segments 204 and 206, respectively, as represented in FIG. 9. The tubing 
segments 204 and 206 are preferably lengths of clear tubing generally used 
in medical applications and are secured to the tubing bores 254A&B in a 
manner known in the art. 
As shown best in FIG. 6, a pair of finger grips 248A&B are each flexibly 
attached to the arms 252A&B, respectively. The flexible attachment of the 
finger grips 248A&B to the arms 252A&B (1) allows the teeth to lockingly 
engage the slots 218A&B when the arms are slid up to the closed ends of 
cutouts 220A&B thus locking the shroud 202 and the body 208 in a fixed 
position relative to each other and (2) allows the user to release the 
teeth 250A&B from the slots 218A&B allowing the shroud 202 and the body 
208 to move with respect to each other. 
As will be further discussed in connection with FIGS. 7 and 8, when the 
second embodiment of the present invention 200 is assembled the plunger 
204 with the plunger tip 206 are held in the shroud 202 with the body 208 
also being inserted into the shroud 202 with the plunger 204 and the 
plunger tip 206 being held captive within the interior of the cylindrical 
vessel 246. To hold all of these components together in their proper 
relationship, an end cap 210 is locked into the open end of the shroud 
202. The end cap 210 includes a plate 258 from which a pair of posts 
261A&B perpendicularly extend. Each of the posts 261A&B are provided with 
claws 260A&B (see FIG. 6), respectively, which engage openings, one of 
which is represented at 222A, provided in the shroud 202. Once assembled, 
the second embodiment can advantageously be utilized to aspirate and expel 
fluids as will next be explained. 
Reference with next be made to FIG. 7 which is an elevational cross 
sectional view of the embodiment illustrated in FIG. 6 in a first 
operational position. In the first operational position all of the fluid 
has been expelled from the second embodiment 200 and a fluid path has been 
created between the tubing bore 254A and the tubing bore 254B. The first 
operational position is also referred to as the normal position since it 
is normal for substantially all of the fluid to be expelled from the 
device except for the fluid which will be described shortly in connection 
with FIG. 7A. 
In the cross sectional view of FIG. 7, the relationship between the shroud 
202 and the body 208 can be observed. In the first operational position 
illustrated in FIG. 7, the cylindrical vessel 246 of the body 208 has been 
pushed as far as possible into the closed end of the shroud 202 towards 
the concentric circle knoll 212. As can be readily observed in FIG. 7, the 
cylindrical vessel 246 has a diameter which closely fits within the 
interior of the cylindrical receptacle 213 of the shroud 202. 
In order to move the body 208 into the first operational position shown in 
FIG. 7, the user preferably places the first end of the shroud 202 having 
the concentric circle knoll 212 against the thumb or palm of a hand. The 
user also places a finger on a first finger rest 253A (located on one side 
of the arm 252A) and another finger on a second finger rest 253B (located 
on one side of the arm 252B). With the first end of the shroud positioned 
against the user's palm or against the user's thumb, and a finger 
positioned on each of the finger rests 253A&B, the user can utilize a 
flexion motion of the fingers and/or the thumb (movement of the fingers 
and thumb toward the palm) to move the body 208 against the first end of 
the shroud 202 to the position represented in FIG. 7. 
As seen best in the cross sectional view of FIG. 7, the prongs 224A&B have 
been received into the openings 214A&B, respectively, holding the plunger 
204 in the shroud 208. The legs 226A&B which support the prongs 224A&B are 
dimensioned such that the plunger fits within the cylindrical vessel 246 
as the body 208 moves within the shroud 202. It will be appreciated that 
the body 208 and the plunger 204 together form a chamber and are one 
preferred arrangement for selectively increasing and decreasing the volume 
or size of the chamber which is formed. 
As the body moves to the position represented in FIG. 7, the volume of the 
chamber volume created by the wall of the cylindrical vessel 246 and the 
first wiper 238 of the plunger 206 is reduced to nearly zero and the fluid 
contained in the body is expelled through passageways 256A&B. A flat end 
240 provided on the plunger tip 206 makes contact with the floor 243 of 
the body 202. As shown in the cross sectional view of FIG. 7A (taken along 
line 7A-7A of FIG. 7), substantially all of the fluid is squeezed out in 
the area where contact is made between the flat end 240 of the plunger tip 
206 and the floor 243 of the body 208. Importantly, a fluid channel 242 
remains to provide a fluid path in the directions of arrows 264 and 
between the passageway 256A and passageway 256B. Significantly, using the 
arrangement represented in the drawing, there is no backspace where blood 
can accumulate and coagulate, as with previously available devices, when 
the apparatus is placed in its normal position. 
The fluid channel 242 is configured to allow fluid flow through the channel 
242 as well as allowing pressure pulses to be transmitted through the 
channel 242. FIG. 9 provides a diagrammatic representation of the second 
embodiment 200 of the present invention including the needleless blood 
sampling site 156, the patient catheter PC, the pressure transducer PT, 
and the fluid source FS. The fluid channel 242 (FIG. 7A) must provide 
suitable fluid flow from the fluid source (FS in FIG. 9) and must 
accurately transmit pressure pulses from the patient catheter (PC in FIG. 
9) to the pressure transducer (PT in FIG. 9). 
The fluid channel 242 is configured to provide a continuous fluid column 
therethrough by minimizing obstructions, reducing the formation of gas 
bubbles, and providing the proper volume of fluid, within the fluid 
channel 242 for accurate transmission of pressure pulses therethrough. The 
configuration of the fluid channel 242 is such that the formation of clots 
therein is minimized. The formation of clots within the fluid channel 242 
blocks the desirable flow of fluid therethrough and degrades the 
transmission of pressure pulses therethrough. The configuration of the 
fluid path 264 provides a smooth transition between the tubes (204 and 206 
in FIG. 9) connected to the tubing bores 254A&B so as to minimize the 
formation of clots and accurately transmit pressure pulses to the pressure 
transducer (PT in FIG. 9). Those skilled in the art will appreciate that 
the materials for the body 208 and the plunger tip 206 should be selected 
from those available in the industry to achieve the enumerated benefits 
among other desirable characteristics discussed herein. 
Reference will next be made to FIG. 8. FIG. 8 is a elevational cross 
sectional view of the second presently preferred embodiment of the present 
invention in a second operational position. When moved to the second 
operational position in the direction indicated by arrows 249, fluid is 
aspirated into the cylindrical vessel 246 of the body 208. In the 
arrangement represented in FIG. 9, moving to the second operational 
position causes the fluid to be drawn up from the patient catheter PC to 
the blood sampling site 156 such that blood, or other bodily fluid, can be 
withdrawn into a sample container (not represented in the figures). 
In order to move to the body 208 in the direction of arrows 249 to the 
second operational position represented in FIG. 8, the user preferably 
places the second end of the shroud 202 having the concentric circle knoll 
262 against the thumb of one hand. The user also preferably places one 
finger (for example a middle finger) on the finger grip 248A and another 
finger (for example a ring finger) on the finger grip 249B. With the 
second end of the shroud 202 and the concentric circle knoll 262 
positioned against the user's thumb and with a finger positioned on each 
of the finger grips 248A&B, the user utilizes a pulling motion to flex the 
finger grips 248A&B to release the teeth 250A&B from the slots 218A&B, 
respectively, as shown best in FIG. 7. 
The finger grips 248A&B are biased so that they engage the slots 218A&B and 
lock the body 202 in its normal position illustrated in FIG. 7. 
Importantly, the device 200 will remain in the normal position most of the 
time during use and the finger grip 248A&B with teeth 250A&B engaging the 
slots 218A&B ensures that the device 200 will remain in the normal 
position even though the device 200 is inadvertently bumped by the patient 
or practitioner or even if the highest expected pressure is introduced in 
the fluid channel. Remaining in the normal position is important to the 
convenient and safe operation of the device 200. 
With the user's fingers preferably positioned as described, the user pulls 
in the direction of arrows 249. The pulling action, which desirably is the 
same action as is used to move the device 200 to its normal position but 
applied to the opposite end of the device, causes the first wiper 240 and 
the second wiper 238 to slide along the interior surface 246A of the 
cylindrical vessel 246 of the body 208. The fluid tight seal formed 
between the first wiper 240, the second wiper 238 and the inner wall 246A 
cause a vacuum to be developed in the chamber formed by the interior 
surface 246A of the cylindrical vessel 246 and the first wiper 238 of the 
plunger 206. The resulting vacuum causes fluid to be aspirated into the 
chamber formed in the body 208. 
Reference will next be made to FIG. 9 which is a diagrammatic 
representation of the second embodiment 200 shown in a normal position. In 
the normal operational position the flow of fluid occurs from the fluid 
source FS, through the pressure transducer PT and the apparatus 200 and 
the associated tubing and structure, to the patient catheter PC. When it 
is desired to obtain a blood sample, the practitioner can preferably grasp 
the apparatus 200 as illustrated in FIG. 9A. Using two fingers and the 
thumb of one hand, the body (hidden within the apparatus 200 in the view 
of FIG. 9) is moved to the sampling position shown in FIG. 9A and fluid is 
aspirated into the chamber formed in the body. 
In view of the forgoing, it will be appreciated that the present invention 
provides a patient fluid sampling system which is compact and convenient 
to operate and which can aspirate blood up to a sampling site with the 
medical practitioner using not more than one hand. The present invention 
also provides an in-line blood sampling system which is reliable and 
inexpensive to manufacture, which minimizes the risk of infection due to 
operation thereof, and which provides a blood sampling system which 
provides appropriate resistance and feel for the medical practitioner 
using the system. 
These benefits of the present invention are in contrast to the 
disadvantages of the previously available devices which require two hands 
to operate or require awkward motions by the practitioner. The present 
invention allows sufficiently large volumes to be aspirated while 
maintaining the apparatus in a small and convenient size. The present 
invention also avoids contamination of the fluid and allows the 
practitioner to use the same motion to return the apparatus to the normal 
position as was used to aspirate fluid. Moreover, the fluid path created 
when the apparatus is in its normal position avoids the formation of clots 
which would otherwise dampen the pressure waves to the pressure transducer 
(PT in FIG. 9) or the flow of fluid to the patient catheter (PC in FIG. 
9). These and other advantages provide a blood sampling system which is 
more efficient and reliable than those previously available. 
The present invention may be embodied in other specific forms without 
departing from its spirit or essential characteristics. The described 
embodiments are to be considered in all respects only as illustrative and 
not restrictive. The scope of the invention is, therefore, indicated by 
the appended claims rather than by the foregoing description. All changes 
which come within the meaning and range of equivalency of the claims are 
to be embraced within their scope.