Presence of shock

Use with high-dose dopamine

Obstructive heart disease with hypoperfusion

Edema

Severe hypothermia

PtcO2 > PaO2

1. Improper calibration

2. Reading taken immediately after electrode application

3. Air bubble beneath membrane or leak to atmosphere

4. Excessive heating temperature

1. Recalibrate

2. Allow longer warm-up period

3. Reapply electrode

4. Attempt calibration at lower temperature

Right-to-left ductal shunt with preductal electrode

and postductal arterial sample

Chapter 10 ■ Continuous Blood Gas Monitoring 73

E. Precautions

See also Chapter 29.

1. This specialized catheter is stiffer and has a wider outer

diameter than other umbilical artery catheters. There is

the theoretical possibility of a higher rate of failure to

insert the catheter and potential increase in rates of vascular spasm and thrombosis.

2. Failure to insert this catheter does not imply that insertion of other arterial catheters will be unsuccessful.

3. The electrode may fail to activate or may lose activation.

4. The catheter should be removed slowly to ensure that

physiologic vasospasm occurs with removal.

F. Technique

1. Use sterile procedure.

2. Prepare the catheter according to the manufacturer’s

instructions.

3. 4 Fr catheters are recommended for infants weighing

<1,500 g.

4. The technique for placement/insertion is the same as

that used for the placement of conventional umbilical

artery catheters (see Chapter 29).

5. Verify catheter position by radiography.

6. Draw blood sample for calibration.

7. Calibrate the monitor according to the manufacturer’s

instructions.

G. Complications

Same as for umbilical artery catheterization. See Chapter 29.

Continuous Umbilical Artery PO2,

PCO2, pH, and Temperature Blood Gas

Monitoring (26–32)

A. Purpose

1. Continuous arterial blood gas monitoring from the

umbilical artery

 Continuous blood gas monitoring through the

umbilical artery offers a means for determining precise

data on a continuous basis.

2. Trending of blood gas data over time

B. Background

1. A very thin, multiparameter, single-use disposable fiberoptic sensor

a. Measures pH, PCO2, PO2, and temperature directly

b. Introduced into the bloodstream via the umbilical

artery catheter

c. Port allows blood sampling, blood pressure monitoring, and drug infusion

2. Calculated parameters include bicarbonate, base

excess, and oxygen saturation.

3. Delivers continuous ventilation, oxygenation, and acid

balance information, while also conserving blood volume by reducing blood sampling

C. Contraindications

1. Previous history or evidence of compromise to the vascular supply of the lower extremity or the buttock area

2. History of previous complications related to an umbilical arterial line

3. Peritonitis

4. Necrotizing enterocolitis

5. Omphalitis

6. Omphalocele

D. Equipment

Previously commercially available monitoring systems have