M22Weaning in practice, extubation and prolonged respiratory failure

Clinical overview

Weaning starts on the day of intubation, not on the day someone remembers to ask. Every hour of unnecessary sedation, immobility and full support adds weakness, delirium and time — and for an obstetric patient it also adds separation from a newborn, interrupted lactation and a delayed start to a recovery that has a family waiting inside it.

M17 covers liberation as a whole-patient, whole-system process. This module is the operational half: what you actually do at the ventilator to move a patient from full support to breathing on her own, how to run and read a trial, and what to do when weaning does not go to plan.

Core knowledge

The daily question

For every ventilated patient, every day: is the reason she was intubated still true? Then screen readiness — improving cause, adequate oxygenation on modest settings (a low FiO₂ and a modest PEEP), haemodynamic stability without escalating vasoactive support, the ability to initiate breaths, manageable secretions and enough consciousness to protect an airway.

Screening is not a formality. The most common reason a patient stays ventilated an extra day is that nobody asked, and the second most common is that sedation was still running out of habit — which is why the awakening assessment and the breathing assessment belong together (M16).

Running a spontaneous breathing trial

A trial asks one question: can she breathe with minimal support for a defined period? Deliver it as low pressure support or on CPAP alone, both are acceptable, for roughly 30 minutes to 2 hours, and judge on what you see rather than on a single index. AARC's 2024 guidance is explicit that calculating a rapid-shallow-breathing index is not required to decide readiness.

Watch for: rising respiratory rate, falling tidal volumes, accessory muscle use, sweating, agitation or new somnolence, tachycardia, arrhythmia, hypertension or hypotension, desaturation, and rising carbon dioxide. And do not stack the deck — increasing the FiO₂ to get a patient through a trial produces a pass that predicts nothing.

Pregnancy adds two considerations. An undelivered patient carries a splinted diaphragm and a higher oxygen demand, so the same trial is genuinely harder for her than for a nonpregnant patient with the same lungs; a "failed" trial may reflect mechanics rather than the underlying disease. And postpartum, mechanics improve rapidly over hours to days — a patient who failed before delivery deserves an early re-screen after it.