MV weaning..the numbers and the scores

INDICES THAT PREDICT SUCCESSFUL VENTILATOR DISCONTINUATION

Respiratory rate <30 breaths per minute

Tidal volume >5 ml/kg or >325 mL

FVC <15 mL/kg (predicts success)

Minute ventilation <15 L/min

— Normal 5 – 6 L/min

— Patient unlikely to wean if > 15 L/min

Maximum inspiratory pressure (PImax) < -30 cmH20

— Measure of respiratory muscle strength

— Normal -90 to -120 cmH2O

Rapid shallow breathing index (RSBI) = f/VT <105 b/min/L

— the ratio of respiratory rate : tidal volume

— often used in conjunction with SBT to determine if it should continue

— some evidence that its use in protocols delays ventilator discontinuation

P0.1/PImax > 0.3

— P0.1 is pressure at the airway opening 0.1 s after start of inspiratory flow

— Correlates with central respiratory drive

P0.1 x f/VT <300

CROP index (compliance, respiratory rate, oxygenation, maximum inspiratory pressure index) >13

— Cdyn x PImax x (PaO2/PAO2)/f

— >13 good

— Cdyn = dynamic compliance

IWI (integrative weaning index) >25

— (CRS x SaO2)/(f/VT)

— CRS = static compliance of the respiratory system

CORE index (compliance, oxygenation, rate, effort) >8

— Cdyn x (PImax/P0.1) x (PaO2/PAO2)/f

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