Hypercapnic Ventilatory Response in the Weaning of Patients with Prolonged Mechanical Ventilation

Abstract EN

Objective.

To investigate whether hypercapnic ventilatory response (defined as the ratio of the change in minute ventilation [ΔV˙E] to the change in end-tidal partial pressure of carbon dioxide [ΔPETCO2]) is a predictor of successful weaning in patients with prolonged mechanical ventilation (PMV) and to determine a reference value for clinical use.

Methods.

A hypercapnic challenge test was performed on 32 PMV subjects (average age: 74.3 years ± 14.9 years).

The subjects were divided into two groups (i.e., weaning successes and weaning failures) and their hypercapnic ventilatory responses were compared.

Results.

PMV subjects had an overall weaning rate of 68.8%.

The weaning-success and weaning-failure groups had hypercapnic ventilatory responses (ΔV˙E/ΔPETCO2) of 0.40±0.16 and 0.28±0.12 L/min/mmHg, respectively (P=.036).

The area under the receiver operating characteristic curve was 0.716 of the hypercapnic ventilatory response, and the practical hypercapnic ventilatory response cut-off point for successful weaning was 0.265 with 86.4% sensitivity and 50% specificity.

Conclusions.

PMV subjects who failed weaning had a lower hypercapnic ventilatory response than successfully weaned subjects.

However, the prediction capacity of this test, assessed by the area under the receiver operating characteristic (ROC) curve, poorly predicted weaning outcome.