Page 589 - Clinical Application of Mechanical Ventilation

Neonatal Mechanical Ventilation 555

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Figure 17-1 Heated wire circuit inside the inspiratory tubing that runs from the humidifier to the
patient connection. The heated wire is attached to a servo-controller for temperature regulation.

higher temperature than the humidifier. As the inspiratory tubing enters the incu-
bator, the gas is heated to the set temperature of the incubator environment. This
To prevent premature causes the temperature probe to sense the higher temperature and shut down the
shutdown (power off) of the
heated wire, the temperature heater wires. The result is a buildup of condensation in the inspiratory tubing.
probe should be placed The solution to this problem is to place the distal temperature probe just outside
just outside the inlet to the
incubator. the inlet to the incubator. This allows the probe to measure the actual gas tempera-
ture and properly regulate the heater wires (Chatburn, 1991).

INITIATION OF NEONATAL VENTILATORY SUPPORT

Indications for neonatal ventilatory support are based on three general guidelines:
apnea, hypercapnia, and hypoxemia. These guidelines are similar to those used for
adult patients. Unlike adult ventilators that use a tidal volume control to adjust the
tidal volume, neonatal ventilators use a peak inspiratory pressure control to deliver
an approximate tidal volume. Another unique feature of most neonatal ventilators
includes the use of the flow rate and inspiratory time (I time) to fine-tune the tidal
volume. The suggested initial ventilatory parameters for neonatal mechanical ven-
tilation are discussed below.

Indications for Mechanical Ventilation

Mechanical ventilation provides two important physiologic functions. First, it
maintains elastic properties and lung volumes by preventing or correcting atel-
ectasis. By maintaining an appropriate functional residual capacity (FRC), lung
compliance is maintained at an optimal level. Mechanical ventilation supplies the
work of breathing when the patient is unable to maintain these properties. Second,
mechanical ventilation provides the appropriate removal of CO and the addition
Mechanical ventilation is 2
indicated when the patient is of inspired oxygen to meet the needs of the patient who cannot maintain arterial
unable to maintain adequate PO or PCO at normal levels.
blood gases during spontane- 2 2
ous breathing. Mechanical ventilation is indicated when any condition causes a decrease in
lung function and an increase in work of breathing that the patient is unable to

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