Cardiac Oscillations Complicating Brain Death Diagnosis

Abstract

Death by neurologic criteria (DNC) or brain death is a clinical diagnosis. It is often complicated by variations in policies as well as confounders on examination. We discuss here the case of a 27-year-old male who had a cardiac arrest following toxic gaseous exposure. He ultimately progressed to brain death but was identified as having cardiac oscillations during clinical assessments that complicated the diagnosis. We discuss the case as well as the maneuvers used to clarify that the "triggered breaths" on the ventilator were indeed cardiac oscillations.

Figure 1

Wine-colored urine. Image shows typical finding in patients who receive hydroxocobalamin as treatment following a toxic exposure. Our patient received hydroxocobalamin following exposure to hydrogen sulfide gas poisoning.

Figure 2

Computed tomography (CT) of the head (CTH). CTH showing diffuse cerebral edema (a) and pseudo-subarachnoid hemorrhage pattern (b, c).

Figure 3

Electroencephalography (EEG): EEG shows electrocerebral inactivity with diffuse cardiogenic artifact. Bipolar montage, sensitivity 7 μv, LF 1.6 Hz, and HF 70 Hz.

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.

Figure 5

Transcranial Doppler (TCD): TCD showing typical systolic spikes in the middle cerebral artery (MCA) bilaterally and the “to-fro” pattern in the anterior cerebral artery (ACA) territory best seen on the right.