The CROP (Compliance, Rate, Oxygenation, Pressure) index incorporates several measures of respiratory function and was developed as a possible guide to weaning patients from mechanical ventilation.
(1) fraction of inspiratory effort reserve per breath: (dynamic compliance) * maximal negative inspiratory pressure)
(2) rate of energy expenditure per minute: (breaths per minute) / ((dynamic compliance) * maximal negative inspiratory pressure))
(3) 1 / (rate of energy expenditure per minute): high values indicate that respiratory demands are well matched by respiratory muscle strength
(4) measure of gas exchange: (PaO2) / (PAO2)
CROP index =
= (dynamic compliance in mL per cm H2O) * (maximal negative inspiratory pressure in cm H2O) * ((PaO2 in mm Hg) / (PAO2 in mm Hg)) / (respiratory rate of spontaneous breathing per minute)
PAO2 can be estimated as follows:
PAO2 in mm Hg =
= ((FIO2 as fraction from 0.21 to 1.00) * ((barometric pressure in mm Hg) - 47)) - (PaCO2 in mm Hg)
• A CROP index >= 13 indicates successful weaning from ventilation in adults with a sensitivity of 81%, specificity of 57%, positive predictive value of 71% and negative predictive value of 70%.
• According to Khan et al, the CROP index may not be useful in weaning infants or children.
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Purpose: To use the CROP index to evaluate a patient for weaning from mechanical ventilation.
Objective: clinical diagnosis, including family history for genetics, other testing, severity, prognosis, stage, complications, selection
ICD-10: J40-J47, R94.2,