Blood collection kit

Details Blood collection kit Blood collection kit

1999-11-09

2001-09-11

Lacyk, John P. (Department: 3736)

Surgery

Diagnostic testing

Liquid collection

Reexamination Certificate

active

06287265

ABSTRACT:

FIELD OF INVENTION
This invention relates to arterial blood collection from arterial lines, specifically to an arterial blood collection kit designed for premature infants with an umbilical artery catheter.
BACKGROUND—DESCRIPTION OF PRIOR ART
In the United States umbilical artery catheters (UACs) are the central line of choice in a neonatal ICU for obtaining arterial blood gases. UACs are also used to monitor internal blood pressure through a transducer attached to the infusing fluids line. UACs are relatively easy to place in a newborn because the umbilical cord is freshly cut and the artery is easy to see. When a neonate is critically ill or premature, frequent arterial blood gases are needed to assess their respiratory status. When an infant is on a ventilator, the blood gas results are used to adjust the ventilator settings appropriately. UACs are only placed in infants needing frequent arterial blood gases, not just to get normal labs or monitor the infant's blood pressure.
A UAC line setup is shown in FIG.
1
and consists of the following: a UAC catheter
22
inserted into a neonate's umbilical artery, a stopcock
24
with a female port
66
, an IV line for infusing fluids
26
, and a transducer for monitoring blood pressure (not shown). The system through the catheter is filled with saline solution and heparin. Slow dripping of saline and heparin into the patient prevents clotting of blood in the catheter and therefore keeps the line open. The infusing fluids usually run at 0.5 cc-1 cc per hour in a neonate.
A currently used process for obtaining blood samples from the female port
66
on the stopcock is described below. Shift the stopcock off to infusing fluids (FIG.
1
B); this opens the fluid path between the catheter and the syringe. Draw 0.5 cc-1.5 cc of blood into the empty 3 cc syringe
28
to clear the UAC of all infusing fluids and bring whole blood to the female port of the stopcock. Shift the stopcock off to all lines (FIG.
1
C). Remove this syringe and keep it sterile. Place a lcc heparinized syringe on the stopcock. Shift the stopcock off to the infusing fluids. Draw back on the lcc syringe until a 0.1-0.3 cc sample is obtained. Shift the stopcock off to all lines. Remove the 1 cc syringe and replace the blood filled 3 cc syringe onto the stopcock. Shift the stopcock off to the infusing fluids. Aspirate on the syringe to remove any air that may be trapped, then give the blood back to the patient. Shift the stopcock off to all lines. Remove the 3cc syringe and place a 3 cc flush filled syringe onto the stopcock. Shift the stopcock off to the infusing fluids. Aspirate on the syringe to remove any air, then flush to clear the line of blood, usually 0.5-1 cc. Shift stopcock off to all lines. Remove the 3 cc flush syringe and place a sterile, empty 3 cc syringe on the stopcock. Shift the stopcock off to the syringe. Now the system is open again to the slow dripping of saline and heparin and ready for the next blood draw.
The foregoing procedure has obvious disadvantages. A large number of manipulative steps are required to carry out the procedure. More important are the many chances for contamination of the female port of the stopcock during the frequent switching of syringes. Neonates can die very quickly and suddenly from sepsis even in a neonatal intensive care setting. The syringe most likely to become contaminated is the first 3 cc syringe used to clear the line of infusing fluids prior to blood sampling. If this syringe becomes contaminated it must be thrown away along with the infant's blood. One may think that 5 0.5 cc-1.5 cc of blood is not that much, but in a 1 to 4 pound infant it is. The blood volume for a neonate is approximately 90 cc/kg* (or 41 cc/lb). For premature infants whose blood volume can be as little as 50 cc or less, anemia is commonly caused by blood draws.* Infants can go into shock if they lose ¼ or more of their blood volume. For example, a micro-premier weighing 500 grams (1 pound 2 ounces) would only have to lose about 11 cc or a little more than 2 teaspoons of blood to go into shock. Infants need the most blood samples taken when they are acutely ill. Arterial blood gases will be drawn every ½ hour to every 4 hours when an infant is on a ventilator. So, one can easily see how often an infant is exposed to contamination and the risk of blood loss.
When using the above procedure for blood sampling, one must be sure to shift the stopcock off to all lines before changing syringes or blood will run out of the open port. Obviously this would lead to more blood loss for the neonate.
An apparatus for drawing arterial blood samples and monitoring blood pressure has been introduced to neonatal intensive care, but seems to be designed with pediatrics or adults in mind. Please see FIG.
2
.
The procedure for drawing from this apparatus is as follows. First make sure a 10 cc flush syringe 40 has 3-8 cc of flush solution in it. There can not be more than 8cc of flush in this syringe or there may not be room to draw back enough blood to clear the line for blood sampling. Shift stopcock
34
so it is off to the infusing fluids. Aspirate on syringe
40
until blood reaches a black line
38
on a tubing
36
to clear the line of infusing fluids and bring whole blood to an access port
30
. Shift stopcock
34
so it is off to everything. Clean an access port
30
and introduce a shrouded needle with a 1 cc heparinized syringe into it. The shrouded needle locks onto the port Shift stopcock
34
so it is off to the infusing fluids. Withdraw 0.1-0.3 cc of blood into the 1 cc syringe and remove it from the sample portMove back to syringe
40
and flush the line to clear it of blood, up to 4 cc of flush is needed at times. Shift stopcock
34
off to syringe
40
, as it is in
FIG. 2
, and the connection between the infusing fluids and the UAC is open again.
While this apparatus has greatly decreased the chance of contamination of the line, it has to also caused many new problems. It is very bulky and spread out. For this reason, many nurses will place an additional stopcock
24
on the line (as I did in
FIG. 2
) and continue drawing blood samples with the procedure described previously. Therefore, the apparatus is used only for transducing the blood pressure and the original contamination risks are still a factor.
Another significant drawback of the apparatus is 2.5 cc of blood has to be aspirated to reach the black line
38
. This is compared to 0.5 cc-1.5 cc drawn off with the first procedure described. Also, more flush is needed to clear the line after blood sampling because the apparatus is so spread out. Although it is designed to require 1 cc of flush, the flush needed to clear the line of blood can be up to 4 cc. More blood drawn off and more flush needed to clear the line is very significant in premature babies. Premature infants and especially micro-premies are most critically ill and most prone to intracranial bleeds during the first few days of life. Intracranial bleeds can be caused by just positioning a premature infant wrong. More important in this instance, intracranial bleeds can be caused by sudden fluid shifts such as taking off or adding fluid to their system suddenly. Also during the first few days of life, when they are most critically ill, is when they need the most arterial blood draws to assess respiratory status.
When an infant needs a bolus of fluid, that fluid is given at 10 cc per kilogram over at least 20 minutes to protect their brain. For example, a 500 kilogram infant would receive a 5 cc bolus over at least 20 minutes. With the current apparatus 2.5 cc of fluid is drawn off the infant. Then that 2.5 cc plus 1 cc-4 cc of flush is added to the infant over a matter of seconds.
If more than the minimal amount of flush is used with a neonate, over a short period of time electrolyte imbalances can occur. Electrolyte imbalances can cause many problems such as cardiac dysrythmias, bronchopulmonary dysplasia, seizures, etc.
With a 10 cc syringe it is difficult to assess exactly how much flush is us

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