Page 9 - 59peadiatric-surgery-speciality8-14_opt

48 Vascular Access in Children
Lower limb
In the lower limb, two veins are usually visible at the lateral border of
the dorsum of the foot, and one at the medial border of the tibia. The
long saphenous and femoral veins may not be readily visible in most
children unless light-complexioned, but they are anatomically just
medial to the femoral artery, which is easily palpable at the groin.
Scalp
The superficial temporal vein is usually prominent in the crying child,
and easy to cannulate by using the butterfly needle.
Arterial punctures
Although the radial artery at the wrist may be big enough in older chil-
dren, the femoral artery at the groin is most commonly used in younger
children. The superficial temporal artery is small but easily palpable.
Bone punctures
The medial border of the tibia is subcutaneous throughout its length.
The proximal part of this subcutaneous border just below the tibia
tuberosity opens into a wide marrow from which blood could be aspi- Figure 9.2: Technique of venepuncture at the wrist.
rated for investigations. Fluids, blood, and drugs could also be rapidly
infused for resuscitation. index finger used as a tourniquet while the rest of the hand steadies the
Technique of Venepuncture child’s wrist (Figure 9.2).
If a vein is not immediately visible, the limb can be placed
Umbilical vein
The umbilical stump of a neonate has two small thick-walled umbilical dependent for a couple of minutes before a tourniquet is applied or the
wrist can be slapped gently.
arteries, and a large, thin-walled umbilical vein, enmeshed in Wharton’s An older patient can be asked to grip and relax the fingers for
jelly (Figure 9.1).
a few minutes. Topical venodilatation may be achieved by topical
8
application of 4% nitroglycerin ointment for 2–4 minutes. Ultrasound,
using a handheld Doppler, can be used to locate forearm veins in obese
Wharton’s jelly patients. The visible or palpable vein is cleaned with antiseptic fluid.
9
The catheter is then inserted until blood fills the chamber. The hub of the
Umbilical vein
catheter is then withdrawn a little and the rest of the catheter inserted.
The infusion fluid is then connected to allow the fluid to open up the
Umbilical artery rest of the vein. The catheter can then be advanced as far as desirable.
Because many children are restless, a small cardboard may be used as a
splint. If two or three attempts on one wrist are not successful, the other
wrist should be tried by a more experienced person.
Cannulation at other sites
Source: Courtesy of Dr. Adeyinka A. Adesiyun, University of Ilorin Teaching Hospital, Ilorin, Nigeria.
Figure 9.1: Transverse section of a neonate’s umbilicus. If attempts at both wrists are not successful, the ante-cubital fossa
should be tried next. If a tourniquet is applied just above the ankle and
the foot is planter-flexed and turned to equinus position, one or two
The baby should be kept warm under a radiant warmer and loosely veins may be visible on the dorsum of the foot. The superficial temporal
restrained. The umbilical cord, clamp, and surrounding skin is cleaned vein over the temple is easily cannulated in children. As the child cries,
with a suitable antiseptic. A size 5 or 6 feeding tube is recommended for the superficial temporal artery is easily palpable and provides a guide
cannulation. This tube is primed with normal saline with a 5-ml syringe to the vein, which is just anterior to it. A scalp vein needle can be used
attached. The base of the umbilicus is tied loosely with a sterile piece for short periods or a cannula for longer periods.
of umbilical tape or 2’0 silk suture to control bleeding. The umbilical Technique of Arterial Punctures
cord is now transected about 3 cm from the base. The vein is picked
with forceps and the catheter inserted and advanced until blood flows Intraarterial cannulation allows the clinician to continuously monitor
back freely into the catheter. Saline in the syringe is injected and should the cardiovascular status of patients and to obtain blood samples for
flow without resistance. The catheter is secured by two purse-string silk blood gases necessary for ventilatory support and acid-base manage-
sutures at the base of the umbilicus, and further taped at several points ment. The umbilical artery at the umbilical stump can be easily cannu-
3
to the skin of the abdomen. lated in neonates. The radial artery at the wrist and the femoral artery
at the groin can also be cannulated percutaneously and for radiological
Cannulation at the wrist procedures. Dorsalis pedis and posterior tibial arteries can also be used.
The first attempt at cannulation at the wrist should be successful in the The brachial artery is usually avoided because of poor collateral circu-
“virgin” wrist if appropriate steps and precautions are followed. All lation; similarly, the superficial temporal arteries are avoided to prevent
necessary equipment should be assembled, including tourniquet, sterile cerebral infarcts.
swabs, appropriate catheters, infusion fluids, and plaster to anchor the For arterial cannulation of limbs, an Allen’s test is first performed.
7
catheter. Adequate illumination is also necessary. The site chosen for In this test, both arteries that supply a limb are compressed for a
cannulation should be cleaned with an antiseptic solution to prevent few minutes. One artery is then released. If the collateral circulation
introduction of organisms ab initio. It is also important for the clini- is adequate, the extremity should flush in colour within 5 seconds.
cian to wear protective gloves to prevent contacting diseases such as The artery can be accessed by either a Seldinger technique or by
10
hepatitis or human immunodeficiency virus (HIV). In venepuncture of a cutdown. Blood products, pressors, calcium boluses, and sodium
the wrist in young children, the wrist could be palmar-flexed and the bicarbonate should not be infused through arterial catheters.