Cardiac Oscillations Complicating Brain Death Diagnosis

Figure 4

Mechanical ventilator waveforms:(a) pressure support (PS) ventilation trial using 100% FiO₂, positive end-expiratory pressure (PEEP) of 5 cmH₂O, and pressure support above PEEP of 5 showing respiratory rate of 25 breaths/min and tidal volume of 152 mL; (b) changing ventilator to a continuous positive airway pressure (CPAP) trial of 100% FiO₂, PEEP of 5 cmH₂O, and pressure support above PEEP of 0 shows respiratory rate of 32 breaths/min and tidal volume of 51 mL. (a) and (b) were with a flow trigger setting at 4 liters per minute; (c) with changing the flow trigger to a pressure trigger (-2 cmH₂O), the pressure and flow waveforms showed a cardiac oscillation pattern which was independent from the heart frequency or heart rate which was 96-102. The increase in peak pressure and flow volume seen at the end of the recording was during an expiratory hold maneuver.

(a)

(b)

(c)