Could the unexpected excessive airway pressure be caused by water in the ventilator circuit?: a case report

Humidification of inhaled gases has been standard of care in mechanical ventilation recently. Heat and moisture exchange is one of the most important functions of the upper respiratory system. The warming and humidification function through the upper airway disappears when mechanical ventilation with endotracheal intubation. An active humidification system is often used to preserve of warming and humidification function. But, we experienced of unexpected high inspiratory pressure and auto-positive end-expiratory pressure (PEEP) during mechanical ventilation with heated wire humidifier that one of active humidification system. We did not find any factor to raise airway pressure other than the water in the inspiratory limb of circuit. After some of sterile water in the circuit removed, high inspiratory pressure and auto-PEEP reduced. So we think that inspiratory limb water is a rare cause of airway pressure rise. Therefore, if sudden high peak airway pressure and auto-PEEP is encountered upon ventilation, the ventilator circuit status should be checked for the safety of patients.