Oxygen Consumption and Alveolar Ventilation During Intermittent Positive Pressure Breathing

Assisted ventilation with a volume-cycled IPPB apparatus decreases arterial carbon dioxide tension by both increasing alveolar ventilation and decreasing the oxygen cost of breathing. In this study, IPPB was shown to reduce the oxygen cost per unit of ventilation by an average of 34 per cent. Dead space ventilation was unchanged, but the alveolar-arterial oxygen difference was increased in all patients, indicating that the distribution of ventilation with IPPB is different from that with spontaneous respiration. These studies indicate that properly administered IPPB increases the efficiency of the respiratory muscles and decreases their entropy.