Ventilator auto‐cycling from cardiogenic oscillations: case report and review of literature

Abstract

This case is presented to arouse the awareness of the medical staff and nurses to this phenomenon, which can mimic an intrinsic respiratory effort in patients allegedly diagnosed with brain death. Along with this case report, we review the English language publications for similar cases.

Ventilator autotriggering

“…In comparison, the flow trigger mechanism is more sensitive to cardiogenic autotriggering than the pressure trigger mechanism [14,16,29]. If the flow-triggering or pressuretriggering thresholds are decreased on the ventilator, the patient requires lower inspiratory efforts for the delivery of an assisted breath; however, reducing the trigger threshold increases the likelihood of false triggering of the respirator due to inadequate flow and pressure sensitivity [22]. Furthermore, VAT can be observed more frequently on new generation ventilators [29], as some have internal programming that allows assisted breaths to ensure oxygen supply to the patient during longer periods of apnea regardless of the trigger setting selected.…”

“…The cardiac cycle and its cyclic variations in pulmonary blood flow [25] can lead to shifts in the intrapulmonary gas volume, which can alter the airway pressure and flow, inducing ventilator self-cycling in brain-dead subjects [1,3,6]. The occurrence of CRO in brain-dead patients is often associated with a hyperdynamic precordium [3,4,22].…”

“…The procedures for identification and correction of VAT overlap with each other [13]. The spectrum of VAT detection measures ranges from simple but insensitive clinical maneuvers testing the patient for chest wall movements in phase with cardiac cycles, to a close assessment of the graphical waveforms of airway flow or pressure with more detailed waveform analysis [22], up to the more advanced technique of monitoring the neurally adjusted coupling of the bioelectrical diaphragm function to ventilator assistance [9]. A way to terminate false triggering is a change from the flow trigger mechanism to pressure trigger [29] because flow-triggered ventilation is more sensitive than pressure-triggered ventilation.…”

What's in this issue?

“…The article by Noujeim et al . () on auto‐triggering of the ventilator details a phenomenon that can lead to delayed assessment of brain death by an apnoea test. The authors have conducted a systematic review of the phenomenon and offer a case history to illustrate the clinical presentation.…”

“…In addition to the cardiogenic oscillations, bronchopleural fistula or an endotracheal cuff leak or air leak could equally set off the auto‐triggering (Noujeim et al . ). In the case history provided by the authors, it was cardiac oscillations that set the ventilator to auto‐trigger.…”