VentPath Simulator
Mechanical ventilation trainer · physiology engine

Sim time 00:00

Case

—

Bedside monitor

live

ECG II

Pleth

Capno

HR bpm

–

SpO₂ %

–

EtCO₂ mmHg

–

MAP mmHg

–

P/F ratio

–

Ventilator waveforms

from dialed settings

Paw · cmH₂O—

Flow · L/s—

Ventilator

set it, then apply

Mode

Airway pressuresPredicted · unapplied

The waveforms and pressures update live as you dial. Blood gas changes only after you apply and time passes.

Arterial blood gas

Interventions

Resuscitation · acute deterioration

Goals for this patient

Debrief · ARDS ventilation

Harm exposure during the case

What happened in your run

Principles

Educational simulation — single-compartment physiology model. Not for clinical use.

Pressure control vs volume control

	Pressure control (PC)	Volume control (VC)
You set	Pressure target, inspiratory time, RR, PEEP	Tidal volume, RR, flow pattern, inspiratory time
Vent varies	Tidal volume & flow (follow compliance)	Peak & plateau pressure (follow compliance)
Trade-off	Airway pressure is capped, but Vt is not guaranteed — it swings with compliance. Decelerating flow suits high drive; alveolar pressure readable from settings.	Vt is guaranteed, but pressure can climb to injurious levels. Plateau must be measured, not inferred.
Reaches for	Severe asthma, COPD, salicylate toxicity	ARDS, obesity, severe burns

Choosing a mode

AC-VC — set Vt, flow, RR, PEEP. Deeply sedated / paralysed, or intermittent spontaneous effort. Can hyperventilate.

AC-PC — set pressure target, Ti, RR, PEEP. Same patients, pressure-limited delivery.

SIMV — set VC or PC + backup RR + PEEP. Regular but weak spontaneous effort; if deeply sedated the set RR must be higher.

PSV — set pressure-support level + PEEP. Spontaneously breathing with good effort; minimal support / weaning.

CPAP — set CPAP level. Alert, spontaneously breathing, rapidly reversible cause. COPD and cardiogenic pulmonary oedema are the classic NIV wins.

BiPAP (bilevel) — set IPAP + EPAP. Like CPAP, with inspiratory assist.

Depth of sedation · RASS

Score	Term	What you see
+4	Combative	Overtly combative or violent; immediate danger to staff
+3	Very agitated	Pulls at or removes tubes/catheters; aggressive
+2	Agitated	Frequent non-purposeful movement; fights the ventilator
+1	Restless	Anxious, but movements not aggressive or vigorous
0	Alert & calm	—
−1	Drowsy	Not fully alert; sustained (>10 s) awakening with eye contact to voice
−2	Light sedation	Briefly (<10 s) awakens with eye contact to voice
−3	Moderate sedation	Movement or eye-opening to voice, but no eye contact
−4	Deep sedation	No response to voice; movement/eye-opening to physical stimulation
−5	Unarousable	No response to voice or physical stimulation

The passive patient this simulator models sits at RASS −4 to −5 — deep sedation, often with early neuromuscular blockade when P/F < 150 (ACURASYS). That is why there is no spontaneous drive to model here.

The distressed ventilated patient · DOPES

First: is the patient acutely UNSTABLE (haemodynamic compromise)?

Yes → take them off the ventilator and hand-bag with 100% O₂, examine, confirm the tube. The immediately lethal causes are tension pneumothorax, severe auto-PEEP (breath-stacking / iPEEP), and massive PE. Improves on bagging → suspect auto-PEEP → resume with a lower rate and longer expiratory time. Doesn't improve → treat presumptively (needle-decompress a tension pneumothorax); still unstable → chase other causes, including PE. In the unstable patient, normal airway pressures point away from lung/airway mechanics and toward PE.

No → confirm tube position, then read the airway pressures:

Peak ↑ AND plateau ↑ → the lung got stiffer (↓ compliance): worsening pathology, pneumothorax, abdominal distension, dyssynchrony / light sedation.

Peak ↑, plateau NORMAL → resistance rose: bronchospasm, blocked or kinked tube, secretions, circuit obstruction.

DOPES — Displacement · Obstruction · Pneumothorax · Equipment · Stacking (auto-PEEP).

This maps straight onto the simulator: the airway-plug stage is peak ↑ / plateau normal (the “O”); the derecruitment and worsening-ARDS stages are the compliance side; the arrest stage (coming) is the unstable branch — bag, then tension pneumothorax / iPEEP / PE.

These cards are original VentPath educational material, re-expressed from primary sources — not a reproduction of any textbook's tables or figures. RASS: Sessler CN et al, Am J Respir Crit Care Med 2002;166:1338–44 & Ely EW et al, JAMA 2003;289:2983–91. Ventilator mechanics & driving pressure: Tobin, Principles & Practice of Mechanical Ventilation; Amato MBP et al, N Engl J Med 2015;372:747. Distressed-patient approach & DOPES: standard critical-care teaching (see also Rosen's Emergency Medicine, Ch. 2, for further reading).

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