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REVERSE TRIGGERING: A newly classified though common form of double triggering

Reverse triggering is a recently defined type of double triggering where a controlled mechanical breath, stimulates receptors in the lung, eliciting inspiratory effort. Seen in patients who are deeply sedated with high mechanical ventilation rates.

Reverse triggering could be explained by respiratory entrainment, a form of patient ventilator interaction, where diaphragmatic muscle contraction is triggered by ventilator insufflations, leading to breath initiation.

Consequences of reverse triggering are large. Continuously induced muscle contraction of diaphragm cause cytokine release and muscle fibre damage. Additionally it increases inspiratory muscle load and oxygen consumption and may lead to cardiovascular instability. Reverse triggering also makes measurement of plateu pressure misleading as well as may generate high platue pressure and ventilator induced lung injury.

Management is not entirely clear. Increasing sedation does not help. Increasing inspiratory time will cause the induced patient effort simply to add into the already delivered tidal volume.

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