Imaging in Neurology

 

Imaging in Neurology

 

 

Fig. 29.12. Some reasons for failure of umbilical artery catheterization. A: Sagittal midline section to

show normal anatomy of umbilical artery. B: Catheter has perforated the umbilical artery within the anulus umbilicalis and is dissecting perivascularly and external to peritoneum. C: Catheter has ruptured

through the tunica intima (t.i.) and dissected into subintimal space. D: Catheter invaginating the tunica

intima after stripping it from a more distal point. (Adapted from Clark JM, Jung AL. Umbilical artery catheterization by a cut down procedure. Pediatrics (Neonatol Suppl). 1977;59:1036, with permission of the

American Academy of Pediatrics.)

Chapter 29 ■ Umbilical Artery Catheterization 163

(2) Position infant on side with same side elevated

as artery being catheterized. Flex hip.

(3) Instill lidocaine as for E23b (3). Do not force

catheter.

e. Easy insertion, but no blood return

(1) Catheter is outside vessel in false channel.

(2) Remove and observe infant carefully for evidence of complication.

24. Place marker tape on catheter with base of tape flush

with surface of cord so that displacement of the catheter

may be readily recognized.

25. Remove umbilical tape and place purse-string suture

around base of the cord (not through skin or vessels).

Three bites into cord (with needle facing away from

catheter) are sufficient to include all three vessels

within the suture.

If desired, form marker tape into bilateral wings, and

sew the tails of the purse-string suture through the

wings to anchor the catheter in a symmetrical fashion.

This is a useful method in very small premature infants

because it avoids sticking tape to the abdominal wall

(27). Alternatively, remove needle and wrap ends of

suture in opposite direction around catheter for about

3 cm and tie, taking care not to kink catheter.

26. Secure catheter temporarily by looping over upper

abdomen and taping.

27. Obtain radiographs or ultrasound to check catheter

position.

a. Catheter tip above T6 or between T10 and L2

(1) Measure distance between actual and appropriate position on radiograph.

(2) Withdraw equal length of catheter.

(3) Repeat radiographic study.

(4) Note procedure in chart.

b. Catheter tip below L5

(1) Remove catheter.

(2) Never advance catheter once in situ, because

this will introduce a length of contaminated

catheter into the vessel.

28. If desired, secure catheter with tape bridge (Fig. 38.14).

29. Continue routine cord care with 70% alcohol swab or

other agent of choice.

30. Stabilize catheter, stopcock, and syringe, using tongue

depressor (optional).

a. Reduces risk of air embolus if syringe is maintained

in vertical position

b. Prevents accidental disconnection of catheter

system

F. Alternative Technique:

Umbilical Artery Cutdown

This method is usually successful even after failed insertion

through the umbilical stump, as there is less tendency for

false tracts. The most frequent reason for failed umbilical

artery cutdown is mistaking the urachus for a vessel.

Because of the time and risks associated with the cutdown

procedure, standard insertion should be attempted first.

Indications

1. Failed umbilical artery catheterization through conventional technique described earlier in this chapter

Contraindications

1. Same as for umbilical artery catheterization by conventional technique

2. Bleeding diathesis

Equipment

1. Same as for umbilical artery catheterization by conventional technique.

2. 1% lidocaine HCl without epinephrine in 3-mL syringe

with 25- to 27-gauge needle

3. No. 15 surgical blade and holder

4. Curved delicate dressing forceps, two pairs (1/4 or 1/2

curved)

5. Tissue forceps

6. Self-retaining retractor (such as eyelid retractor)

7. Absorbable suture, plain

8. Absorbable suture on small cutting needle

9. Nonabsorbable suture on a small, curved needle

10. Needle holder

11. Suture scissors

12. Skin-closure tapes

Precautions

 

1. Same as described earlier for conventional technique.

2. If possible, leave catheter from previously attempted standard procedure in place to aid in vessel identification.

3. Ensure that abdominal incision is on abdominal wall

and not too close to umbilical stump.

4. Identify landmarks carefully to avoid cutting or catheterizing urachus.

5. When incising mesenchymal sheath, take care to avoid

transecting vessel.

6. Secure the catheter with an internal ligature that is just

tight enough to prevent accidental removal but loose

enough for elective removal or reinsertion, in case

the catheter becomes occluded by thrombus or precipitate.

Technique (28)

See Fig. 29.13.

1. Insert an orogastric tube to keep the bowel as decompressed as possible.

2. Prepare infant and drape as for umbilical artery catheterization (see earlier in chapter).

3. If catheter has been left in place after previous attempt,

include vessel and catheter in the preparation, leaving

the catheter accessible for removal.

164 Section V ■ Vascular Access

4. Anesthetize area of skin immediately below umbilicus,

at umbilical stump–abdominal wall junction, with

0.5 mL of lidocaine.

5. Prepare UAC as for standard procedure, leaving catheter filled with flush solution. Estimate length for insertion based on patient size. Subtract 1 to 2 cm from that

recommended for standard insertion, as cutdown catheter will enter vessel farther along course.

6. Make a smile-shaped incision from 4 to 8 o’clock

through the skin of the abdominal wall at the junction

with the umbilical stump.

7. Place self-retaining retractor to maintain exposure.

8. Using blunt dissection through the subcutaneous tissue

with mosquito forceps, identify the fascia overlying the

urachus and umbilical vessels.

The mesenchymal sheath is composed of three layers of fascia and is from 1 to 3 mm thick. Although it is

barely perceptible in extremely premature infants, in

term infants it may be thick enough to require making

an incision through the sheath prior to blunt dissection.

9. While elevating the fascia with two forceps, make a

small incision between their tips. Enlarge incision with

scissors to the same size as skin incision. In very immature infants, simple dissection should suffice.

10. With curved mosquito forceps, dissect in the midline

and identify the urachus (Fig. 29.13).

The urachus is a white, glistening, cordlike structure

in the midline. Its position may be confirmed by traction cephalad, pulling the dome of the bladder into

view. The umbilical arteries lie posterolaterally on

either side but not touching the urachus.

11. Identify the umbilical arteries lying to either side of the

urachus.