256 Section VII ■ Tube Replacement

(2) Negative pressure of 20 cm H2O evacuates more

than 4 L of air/min in experimental setting (4).

(a) Appropriate starting point for most infants

with lung disease on ventilators is 10 to

15 cm H2O

(b) Potentially inadequate in a case of bronchopleural fistula

(c) Excessive suction pressure may draw tissue

into the side holes of the chest tube and

could also be potentially harmful by changing intrapulmonary air flow in presence

of smaller pleural leak (always start with

10 cm H2O).

Measured rates across bronchopleural

fistulas in infants have indicated ranges

from 30 to 600 mL/min (5). If suction pressure is too high, gas flow to alveoli may be

diverted across a fistula. The pressure and

flow applied to the endotracheal tube also

directly influence flow across a fistula (5).

Because there are many interactive factors

influencing how much air might have to be

evacuated, there can be no single best suction level for all patients; the most effective,

least harmful level has to be determined for

each situation (6).

7. Nonabsorbable suture on small cutting needle, 4.0

8. Cotton-tipped applicators

9. Semipermeable transparent dressing

10. Antibiotic ointment

11. Petroleum gauze

Nonsterile

1. Tincture of benzoin

2. 0.5-inch adhesive tape

3. Transillumination device

4. Towel roll

D. Factors Influencing Efficiency

of Air Evacuation

1. Contiguity of air to chest tube portals; they must be

patent

a. In supine infant, air accumulates in the medial,

anterior, or inferior hemithorax, making low

anterior location for tip of tube ideal for evacuation (7).

b. Negative pressure on chest tube may draw tissue

into side portals and occlude them.

2. Rate of air accumulation is proportional to

a. Airway flow and pressure

Dennis et al. (8) demonstrated in experimental

rabbit models that a positive end-expiratory pressure

level >6 cm H2O resulted in greater air leak than

peak inspiratory pressures up to 30 cm H2O.

Fig. 38.1. Pigtail catheter for pleural drainage (Fuhrman pleural drainage set). (Illustration provided by

Cook Critical Care, Bloomington, Indiana).