Table 1. Etiology-based Framework for Ventilator Weaning: Summary of Category-specific Assessment, Intervention, Weaning Endpoint, and Venue

Category	Representative etiologies	Dominant pathophysiology	Domain-specific assessment	Ceiling intervention (cause-specific)	Weaning endpoint	Recommended weaning venue
PULMONARY	Acute: ARDS, severe pneumonia, COPD exacerbation, post-thoracic surgery atelectasis, heart failure / weaning-induced pulmonary edema	Impaired gas exchange and lung mechanics	P/F ratio; ABG; compliance; plateau pressure; lung ultrasound; RSBI	Positioning (prone / semi-prone); airway clearance (PEP, ACBT); recruitment maneuvers; graded mobilization	Standard extubation after SBT pass	ICU
	Chronic restrictive: Post-tuberculosis destroyed lung; severe kyphoscoliosis	Chronic hypercapnia from a fixed restrictive defect	ABG; nocturnal SpO2 / capnography; FVC	Chronic NIV (nighttime ± daytime); where feasible, primary NIV from the outset to avoid intubation	Transition from invasive MV to chronic NIV	Location-flexible: ICU if admitted there, otherwise step-down ward; → home NIV
MUSCLE	Acquired (ICU-AW / VIDD): Sepsis-related ICU-AW; VIDD; prolonged immobilization	Recoverable respiratory muscle weakness with systemic deconditioning	MIP / MEP; diaphragm ultrasound (thickening fraction); MRC sum score; PCF	Inspiratory muscle training (IMT); early mobilization; NMES when not mobilizable; PADIS-integrated care; nutritional optimization	SBT-based extubation once muscle reserve recovers (the SBT framework applies here)	ICU (SBT attempt first); if SBT fails, weaning continues in rehabilitation ward / weaning unit after sufficient rehabilitation
	NMD: Duchenne muscular dystrophy; ALS; Guillain-Barré syndrome; high cervical spinal cord injury; phrenic nerve injury	Non-recoverable or progressive respiratory muscle weakness	MIP / MEP; supine FVC; PCF; nocturnal capnography / SpO2; bulbar assessment	NIV initiation and titration; MI-E for secretion management; where feasible, primary NIV from the outset to avoid intubation; if NIV fails → tracheostomy as bridge to NIV	Transition from invasive MV to NIV (not SBT-defined); decannulation when PCF and MIP stabilize	Location-flexible: ICU if admitted there, otherwise general / rehabilitation ward; respiratory rehabilitation center; home NIV
BRAIN	Brainstem stroke (medulla / pons); hypoxic brain injury; post-cardiac arrest	Impaired central chemosensitivity and respiratory drive	Brainstem reflexes; level of consciousness; breathing-pattern observation; brainstem MRI; capnography; swallow / aspiration assessment (frequent overlap with the aspiration category)	Ventilator settings matched to impaired chemosensitivity (avoid hypocapnia; maintain baseline PaCO2); removal of residual sedatives / opioids; treatment of demand-modifying factors (infection, pressure ulcers); cognitive rehabilitation during alert periods	Reliable spontaneous triggering under appropriate settings; acceptance of a new baseline (mild hypercapnia; supplemental O2); a tracheostomy (T-tube) may be maintained where drive or airway protection does not recover	Rehabilitation ward / specialized weaning unit (out of ICU; weeks to months, within the 6–12 month recovery window)
ASPIRATION	Stroke; TBI; hypoxic brain injury; bulbar weakness (ALS, MG, late-onset NMD); Parkinson's disease; advanced age with sarcopenia	Failure of airway protection (swallow and cough)	VFSS; FEES; direct bulbar exam; PCF; clinical assessment of aspiration frequency and secretion burden	Swallowing therapy and oral hygiene; cough augmentation (manually-assisted cough, MI-E); salivary control (anticholinergics, botulinum toxin); tracheostomy as a manageable airway platform	Establishment of a managed airway platform (tracheostomy); decannulation considered only if cough and swallow function recover — not a guaranteed endpoint *	Out-of-ICU rehabilitation setting; long-term tracheostomy / care if airway protection does not recover

The framework comprises four categories (pulmonary, muscle, brain, aspiration); the pulmonary and muscle categories each contain two clinically distinct subgroups, shown as nested rows. Floor interventions — early mobilization, sedation minimization, nutritional optimization, and skin / joint care — apply universally to every ventilator-dependent patient regardless of etiology and are not repeated in each row. Recommended weaning venue denotes the clinical setting in which the weaning process is conducted, not the patient's final disposition: weaning in the acute pulmonary category is appropriately completed within the ICU, whereas for the remaining categories it need not be completed in the ICU and may proceed in settings beyond it.
In the aspiration category, the weaning endpoint is defined by airway protection rather than ventilatory capacity. Because the representative etiologies include brain injury (stroke, TBI, hypoxic brain injury) in which airway protection may not recover, maintenance of a tracheostomy (T-tube) is frequently the appropriate long-term outcome; decannulation is pursued only when cough and swallow function recover sufficiently and is not a guaranteed endpoint.
ABG: arterial blood gas, ACBT: active cycle of breathing technique, ALS: amyotrophic lateral sclerosis, ARDS: acute respiratory distress syndrome, COPD: chronic obstructive pulmonary disease, FEES: fiberoptic endoscopic evaluation of swallowing, FVC: forced vital capacity, ICU: intensive care unit, ICU-AW: ICU-acquired weakness, IMT: inspiratory muscle training, MEP: maximum expiratory pressure, MG: myasthenia gravis, MI-E: mechanical insufflation-exsufflation, MIP: maximum inspiratory pressure, MRC: medical research council, MV: mechanical ventilation, NIV: non-invasive ventilation, NMD: neuromuscular disease, NMES: neuromuscular electrical stimulation, PADIS: pain, agitation/sedation, delirium, immobility, sleep, PCF: peak cough flow, PEP: positive expiratory pressure, P/F: PaO₂/FiO₂, RSBI: rapid shallow breathing index, SBT: spontaneous breathing trial, TBI: traumatic brain injury, VFSS: videofluoroscopic swallowing study, VIDD: ventilator-induced diaphragm dysfunction.