Comparison of 3 different methods used to measure the rapid shallow breathing index

The RSBI values measured through the ventilator with CPAP 5 cm H2O are much lower than the values measured with a handheld spirometer. Even the RSBI values measured with CPAP 0 cm H2O are significantly lower. This is attributable to the base flow delivered by some ventilators. The difference must be taken into account during weaning assessment.