Combined high frequency ventilation in the management of respiratory failure in late pregnancy

We describe a pregnant patient with respiratory failure due to an atypical pneumonia and asthma that was successfully treated with the combination of high frequency oscillatory ventilation and intermittent positive pressure ventilation. This combined high frequency ventilatory technique is not commonly used in adults with respiratory failure and is largely contraindicated in patients with prolonged respiratory time constants such as occurs in asthma because of the risk of gas trapping. We suggest that this technique be considered in cases of respiratory failure refractory to conventional intermittent positive pressure ventilation and, that with appropriate monitoring of airways pressure, is worthy of a trial in patients with prolonged respiratory time constants.