Hemodynamic and ventilatory complications of mechanical ventilation with high intrinsic positive end-expiratory pressure

In three mechanically ventilated patients ventilatory and circulatory complications resulted from high levels of intrinsic positive end-expiratory pressure (PEEPi): progressive pulmonary hyperinflation due to impairment of the expiration. PEEPi was initially not considered as the cause of shock and low tidal volumes and/or high inflation pressures. In a 74-year-old man the circulation deteriorated further when hand bagging was started in an attempt to improve his ventilatory condition; after reduction of the respiration rate, he recovered well. In a 40-year-old woman with relapsing polychondritis sedation helped to reduce the respiratory rate so as to restore sufficient expiratory time. A 59-year-old woman developed acute exacerbation of severe chronic obstructive pulmonary disease, and went into shock during interhospital ambulance transport; she was stabilized after recognition of PEEPi and adjustment of the setting of the ventilator. Detection of PEEPi (e.g. by the finding of a deep inflation level on physical examination) is more important than exact measurement of PEEPi. If PEEPi is detected, the ventilator should be set at PEEP at 80-90% of PEEPi, low frequency (e.g. 8/min) and a long expiratory time, and high inspiratory flow.