Mechanical ventilation
Invasive and noninvasive positive pressure ventilation support gas exchange and reduce work of breathing in hypoxemic or hypercapnic respiratory failure, upper airway impairment, or inability to protect the airway.
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What this article covers
- Overview
Mechanical ventilation is positive-pressure respiratory support, delivered noninvasively (mask/helmet) or invasively (endotracheal tube or tracheostomy), that takes over or augments the work of…
- Epidemiology
Invasive mechanical ventilation is one of the most common ICU interventions, required whenever respiratory failure or upper airway impairment cannot be managed noninvasively.
- Risk factors
Hypoxemic respiratory failure from alveolar flooding or collapse (pneumonia, pulmonary edema, ARDS) or shunt physiology.
- Pathophysiology
Adequate spontaneous ventilation requires muscle pressure sufficient to overcome elastic (lung and chest wall) and resistive (airway) loads; failure results when loads rise too high or the muscles become too weak.
- Clinical features
Signs of impending respiratory failure: tachypnea, accessory muscle use, paradoxical abdominal breathing, inability to speak in full sentences, diaphoresis, nasal flaring, altered mental status.
- Differential diagnosis
Cardiogenic pulmonary edema: bilateral crackles, elevated jugular venous pressure, S3, elevated BNP; echocardiographic left ventricular dysfunction confirms it, and it responds to CPAP/BPAP plus diuresis.
- Diagnosis
The decision to ventilate is clinical, established on the indications for support rather than a single diagnostic test: hypoxemic or hypercapnic respiratory failure, an NPPV contraindication or…
- Management
First, secure the airway with rapid sequence intubation: induction agent immediately followed by a paralytic.
- Complications
Ventilator-induced lung injury: volutrauma from overdistension and atelectrauma from repeated opening/closing, minimized by lung-protective tidal volume and plateau pressure limits.
- Prognosis
Outcome is driven mainly by the underlying disease rather than the ventilator itself; in ARDS, mortality reflects the precipitating illness, secondary infection, or multiorgan dysfunction more than…
- Prevention
Use lung-protective ventilation from the start: tidal volume 4-8 mL/kg predicted body weight, plateau pressure below 30 cm H2O.
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