TRIPASS XR تري باس

 

174 Section V ■ Vascular Access

and left lobes of the liver in the median sagittal plane of the

body, at a level between the 9th and 10th thoracic vertebrae; it terminates in the inferior vena cava along with

hepatic veins, as shown in Fig. 30.1.

1. Make necessary measurements to determine length of

catheter to be inserted, adding length of umbilical

stump (Figs. 30.1 and 30.2) (4).

2. Prepare for procedure as with umbilical artery catheter

(see Chapter 29, E).

3. Identify thin-walled vein, close to periphery of umbilical stump (Fig. 30.2).

4. Grasp cord stump with toothed forceps.

5. Gently insert tips of iris forceps into lumen of vein and

remove any clots.

6. Introduce fluid-filled catheter, attached to the stopcock

and syringe, 2 to 3 cm into vein (measuring from anterior abdominal wall).

7. Apply gentle suction to syringe.

a. If there is not easy blood return, the catheter may

have a clot in the tip. Withdraw the catheter while

maintaining gentle suction. Remove clot and reinsert catheter.

b. If there is smooth blood flow, continue to insert

catheter for full estimated distance.

Fig. 30.1. Anatomy of the umbilical and associated veins, with

reference to external landmarks.

Fig. 30.2. The umbilical stump. Vein is indicated with an arrow.

8. If catheter meets any obstruction prior to measured distance

a. It has most commonly

(1) Entered portal system, or

(2) Wedged in an intrahepatic branch of portal vein

b. Withdraw catheter 2 to 3 cm, gently rotate, and reinsert in an attempt to get tip through ductus venosus.

9. If the catheter is in the portal circulation, leave the misdirected catheter in its place. Pass a new 3.5- or 5-Fr

catheter into the same vessel. Once the catheter is in a

good position, remove the misdirected catheter. This

procedure has a 50% success rate (5).

10. Obtain radiographic verification of catheter position. A

lateral radiograph will aid in exact localization (Fig.

30.3) (6,7). The desired location is T9 to T10, just

above the right diaphragm. The catheter tip position

may be estimated clinically by measurement of venous

pressure (1) and observation of waveform (Figs. 30.4

and 30.5). The catheter has crossed the foramen ovale

if the blood obtained is bright red (arterial in appearance). In this case, pull the catheter back.

a. As soon as the catheter has been advanced 2 to 3 cm

into the vein, have an assistant connect it to a pressure-monitoring system (see Chapter 9).

b. While continuing to advance the catheter, measure

venous pressure and note pressure changes with respiration (Fig. 30.4). The ideal position is with the

catheter tip at the junction of the inferior vena cava

and the right atrium, although placement in ductus

venosus is acceptable for purposes other than measurement of central venous pressure.

11. Other modalities to evaluate catheter placement

include ultrasound (8) and echocardiography (9).

These techniques may require fewer manipulations

during catheter placement and reduce the number of

x-rays a patient receives. Additionally, these types of