Table 3.

Studies identifying risk factors for PMV

First author, ID	Patients	ICU setting	PMV pts. (%)	Risk factors
Béduneau et al. [1]	Pts. receiving MV	36, 10–17-bed. ICUs	399 (22)	Age (year), SOFA at admission, duration of MV before the first separation attempt, medical admissions
Chang et al. [19]	Pts. who survive sepsis/septic shock with respiratory failure	MICU	72 (29)	Previous stroke; platelets ≤150,000/μL, pH ≤ 7.35, FiO2 ≥ 0.39 (on admission day 7)
Clark et al. [18]	MICU pts.	16-bed MICU	31 (31.3)	I-TRACH score: intubated in MICU, HR >110/min, BUN >25 mg/dL, pH >7.25, Creatinine >2.0 mg/dL, HCO3 >20 mEq/L
Clark et al. [20]	MICU pts.	12-bed MICU	34 (19.7)	I-TRACH score; intubated in MICU, HR >110/min, BUN >25 mg/dL, pH >7.25, creatinine >2.0 mg/dL or a >50% increase from baseline values, HCO3 >20 mEq/L
Figueroa-Casas et al. [24]	Medical, surgical, and trauma pts. MV ≥2 consecutive mornings	General ICU	110 (39)	Level of PEEP (from the first 2 days on MV)
Goligher et al. [25]	ICU pts., MV ≥36 h		61 (31.9)	Decrease as well as increase of diaphragm thickness, measured daily by ultrasound
Greenberg et al. [23]	Tracheotomized pts. undergoing MV		103 (44.7)	VIS (ventilator independence score) (on day after, tracheostomy placement), CCI, serum albumin (on hospital admission), g/dL, SOFA score (on ICU admission)
Hermans et al. [22]	Medical and surgical study pts. in the ICU for at least 7 days	MICU	171 (40.7)	Intensive insulin therapy
Hsieh et al. [29]	ICU patients planned for extubation	96 ICU beds; 48 medical, 9 cardiac 39 surgical	311 (8.6)	Artificial neural network model with 47 different 47 clinical risk factors
Pan et al. [17]	Pts. on MV admitted to respiratory ICU	35-bed respiratory ICU	41 (26.6)	Acute kidney injury, MV days before the day of readiness for weaning, RSBI on day of readiness for weaning
Papuzinski et al. [16]	Pts. required invasive MV	General ICU	142 (40.7)	Age, PaO2/FiO2 >200, Hypernatremia (at intubation), COPD
Pu et al. [26]	Patients intubated, MV ≥24 h, undergoing SBT	Medical and surgical ICUs of 13 hospitals	44 (13)	Glasgow Score PaCO2 (at the beginning of the first SBT)
Sellares et al. [28]	Patients intubated, MV ≥48 h, ready to wean	6-bed respiratory ICU	33 (18)	Increased heart rate ≥105 min−1, PaCO2 ≥54 mm Hg (during the spontaneous breathing trial)
Wang et al. [21]	Pts. who were admitted to the ICU after cardiac surgery		26 (46.4)	Poor cardiac function (ventricular-vascular coupling ratio), lactate at admission

The table shows the studies that examine the risk factors for PMV including prolonged weaning. ICC, International Consensus Conference; ICU, intensive care unit; MICU, medical intensive care unit; MV, mechanical ventilation; FiO₂, fraction of inspired oxygen; HR, heart rate; BUN, blood urea nitrogen; HCO₃, bicarbonate; PEEP, positive end-expiratory pressure; VIS, ventilator independence score; CCI, Charlson Comorbidity Index; SAPS II, Simplified Acute Physiology Score; SOFA, Sequential Organ Failure Assessment; SBT, spontaneous breathing trial; PaCO₂, partial pressure of carbon dioxide; SICU, surgical intensive care Unit; RSBI, rapid shallow breathing index; eGFR, estimated glomerular filtration rate; PaO₂/FiO₂, ratio of arterial oxygen partial pressure to fractional inspired oxygen; DPC, Diagnosis Procedure Combination database; RCC, respiratory care center; Acute Physiology and Chronic Health Evaluation.