Patient–ventilator interaction

Asynchrony Atlas

Lungs, diaphragm, and ventilator on one clock — failed, late, early, and auto triggers, both cycling errors, and double triggering.

Pace
Severity

In phase

Ventilator triggers within a short delay

Patient 20/min·Ventilator 20/min

Paw
17.0cmH₂O
Flow
0.96L/s
Volume
348mL
Pmus
−5.1cmH₂O
VENTILATORPSV17cmH₂OPS 12 · PEEP 5gas outto the lungs →← to the ventilatorRLDIAPHRAGM

Tracings

  • Pressure, volume, ventilator
  • Flow
  • Pmus · negative is inspiration
PawcmH₂OFlowL/sVolmLPmuscmH₂O00PtVent0s1s2s3s

Space plays and pauses. Arrow keys scrub. Terracotta wash is effort, teal wash is insufflation.

Effort with the breath

Synchronous

Neural inspiration and the mechanical breath occupy essentially the same window. The trigger delay is short — well under 200 ms — and the ventilator cycles off near the end of the patient's effort.

On the tracing

Airway pressure lifts as muscle pressure rises. Inspiratory flow decelerates and is near zero at cycling. The diaphragm and the lungs move together, and the phase bars overlap.

Why it happens

Trigger sensitivity, pressurization, and the cycling threshold match this patient's drive, and auto-PEEP is not hiding the effort.

This is the reference pattern. Work of breathing stays low, and tidal volume reflects the support you think you set.

Teaching schematic of pressure-support breaths in a one-compartment lung. Not a ventilator recording and not for clinical decisions. Positive flow is inspiration. Inspiratory muscle pressure deflects downward, as esophageal pressure does. The dashed line upward is expiratory muscle pressure.