Assisted Ventilation for Pediatric Patients

Published on 01/06/2015 by admin

Filed under Pulmolory and Respiratory

Last modified 01/06/2015

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Chapter 30

Assisted Ventilation for Pediatric Patients

General Concepts of Ventilation (Box 30-1)

Alveolar ventilation: The measure of the adequacy of ventilation; CO2 removal is directly related to alveolar ventilation.

Compliance: The measure of distensibility of the lungs and thorax expressed as the volume change in the lung per unit of pressure change. The higher the compliance, the greater the volume change in the lungs for a given change in pressure. With a reduction in compliance, a greater pressure gradient is required to move a given volume of gas into the lungs.

Resistance: The measure of the tendency for the airways and lung tissue to resist the flow of gas expressed as the change in pressure per unit of gas flow: the greater the resistance to gas flow, the greater the pressure gradient necessary to deliver a volume of gas in a given time interval.

Time constant: The relationship between compliance and resistance and pressure equilibration between patient and ventilator circuit, or filling and emptying of the lungs during inspiration and expiration. One time constant is the measure of the time necessary for alveolar pressure to equilibrate to 63% of a change in airway pressure; 99% pressure equilibration occurs in lungs with normal compliance and resistance in approximately five time constants.

II Continuous Positive Airway Pressure (CPAP)

General description

Clinical applications

CPAP generators

III Types of Ventilation

Control variables

Pressure-control ventilation (PCV)

1. Pressure is the variable that the ventilator controls to effect inspiration.

2. The shape of the inspiratory pressure waveform remains consistent breath to breath as compliance and resistance change.

3. Flow pattern and delivered tidal volume (Vt) vary depending on changes in compliance and resistance.

4. Volume delivery primarily depends on the change in pressure from baseline to peak pressure, referred to as delta-P (ΔP).

5. As the lungs fill and lung pressure approaches the set pressure target or limit (circuit pressure), the inspiratory gas flow rate to the patient decreases or decelerates.

6. Time-cycled, pressure-limited (TCPL)

Pressure support ventilation (PSV)

Volume-control ventilation (VCV)

Dual control

IV Modes of Ventilation

Assist control (AC)

Synchronized intermittent mandatory ventilation (SIMV)

Spontaneous modes

Combined modes

Indications for Mechanical Ventilation (Box 30-2)

VI Pediatric Ventilator Settings