Duan et al developed the HACOR score for evaluating a hypoxic patient placed on noninvasive ventilation. This can help to identify a patient failing this form of respiratory support. The authors are from the First Affiliated Hospital of Chongqing Medical University in China.
Patient selection: spontaneous breathing trial
Requirements: improvement in cause of respiratory failure, PaO2 >= 60 mm Hg, oxygen saturation >= 90%, FIO2 <= 0.4, PEEP <= 5 cm H2O, respiratory rate <= 35 breaths per minute, rectal temperature < 38°C, hemoglobin >= 8 g/dL, no respiratory depressants for >= 48 hours
Outcome: success or failure
Parameters:
(1) CROP (Compliance, Rate, Oxygenation, Pressure) index
(2) P0.1 (airway occlusion pressure 0.1 seconds after start of inspiratory flow)
P0.1 is determined from airway pressures measured on the ventilator:
(1) At the end of an expiration the inspiratory valve closes.
(2) Measurement starts when a negative pressure of -0.5 cm H2O is measured and indicates the start of inspiratory effort.
(3) A second airway pressure reading is taken 0.1 second later.
(4) P0.1 is the pressure difference between start and finish.
(5) A P0.1 <= 3.8 is associated with successful SBT.
CROP =
= (CORE index) / (P0.1)
Interpretation:
• A CROP index > 8 had a 100% sensitivity and 95% specificity for SBT success.
