Controlled Ventilation with Intermittent Positive-Pressure Breathing in the Management of Acute Ventilatory Failure Associated with Chronic Obstructive Pulmonary Disease

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Abstract
Controlled mechanical ventilation employing IPPB [intermittent positive pressure breathing] in 19 patients with chronic obstructive lung disease in acute failure (PaCO2 [arterial CO2 pressure]> 55 mmHg, pH < 7.25, PaO2 -c 60 mm Hg) when assisted ventilation failed. The indications for controlled cycle were poor patient cooperation, O2 depression of ventilation, or inability to reduce PCO2 or [H+] or to improve PO2. In 19 patients with 21 episodes of acute ventilatory failure, 4 trials were managed by assisted ventilation. The remaining 17 episodes were managed by automatic machine cycle, O2 suppression, or drug suppression (morphine and/or succinyl choline). Forty-one percent of the cases, most of them obtunded and comatose, were managed by machine cycle alone. With agitated, uncooperative patients, O2 suppression was effective in establishing control in 18%, and drug suppression (morphine, and/or succinyl choline) in 41%. Once a patient was synchronized, effective ventilation could be achieved. Mean falls of 30-57 mm Hg PaCO2, improvement in pH 0.14-0.21 units, and PaO2 17.8 - 198 mm Hg were observed. Ventilatory improvement was best achieved by reduced respiratory rates and increases in tidal volumes. Problems encountered were: hypotension with hish pressures, gastro-intestinal bleeding, cardiac arrest, arrhythmias and shock. The mortality rate was 41%. Properly selected and with constant medical-nursing care controlled ventilation with IPPB is useful in cases of ventilatory failure which are refractory to conventional assisted IPPB.