Mode, TAG? @ArielG_RRT @emireles_c

Delighted to introduce our new blog and website, “ventilator waves”, dedicated to mechanical ventilation and ventilator graphics interpretation. https://t.co/kZJs82JNAg

occurs before neural inspiration #mechanicalventilation #ventilatorwaves

The appearance of notch in the pressure waveform (1) with a sudden surge in inspiratory flow reflects diaphragm contraction initiated by passive mechanical inflation. This phenomenon, known as “reverse triggering”, is also called “early triggering” because mechanical inflation

How would you interpret this waveform? #mechanicalventilation #ventilatorwaves

Key message: Ventilators may incorrectly label false triggers as patient-initiated breaths. Differentiation requires careful recognition of Pmus and identification of the underlying cause of the false trigger—most commonly cardiac oscillations, secretions, or air leaks.

In this example, the underlying mechanism of false triggering is cardiac oscillations, visible as smooth oscillations in the expiratory flow–time scalar. These oscillations initiated the first and third breaths, with the third breath being followed by a true inspiratory effort.

Third breath: appears patient-triggered, but closer inspection reveals a notch in the pressure–time scalar with a concomitant rise in inspiratory flow. This indicates that neural inspiration occurred shortly after a false trigger, initially caused by cardiac oscillations.

First breath: Although labeled as patient-triggered, its passive morphology suggests it is likely a false trigger. Second breath: Here, Pmus is evident, producing higher tidal volumes and an altered flow–time morphology, confirming a true patient effort.

Identifying Pmus (the negative pressure generated by respiratory muscles) is essential in differentiating true patient efforts from false triggers.

However, ventilators cannot reliably distinguish between true patient efforts and non-patient signals (e.g., cardiac pulsations). As a result, they may incorrectly label false triggers as patient-triggered breaths, potentially leading to misinterpretation of ventilator waveforms.

In this case, flow triggering was used. The breaths appear to be patient-triggered, as suggested by a small negative deflection in airway pressure preceding inspiration and the pink marking on the flow–time scalar.

The following waveform shows three consecutive breaths, each with distinct morphologies. On this ventilator (Maquet, Getinge), patient-triggered breaths are marked in pink at the initial rise in pressure and flow, corresponding to pressure or flow triggering.

How would you interpret this waveform?

Double trigger due to early cycling

How would you interpret these waveforms?

@Vent_Busters @OfVentilation @ventilacionmeca @RespiratorySCCM @SaudiRTs @RespiratoryZone @respcare @DrSateeshPCCM @IM_Crit_ @critconcepts @CCF_PCCM @MegriMohammed @_MSAMEED

To prevent an excessively long inspiratory phase, the ventilator activates a backup time based mechanism to terminate inspiration (time cycling).

In pressure control or pressure support mode, an air leak causes the ventilator to increase flow in an attempt to maintain set pressure. As a result, flow does not drop to the cycling threshold, leading to prolonged inspiration.

Meanwhile the patient completes one full breath cycle (inspiration and expiration) and initiates another breath, leading to a second peak in the inspiratory flow- time scalar.