Optimal time needed for withdrawal of mechanical ventilation in patients with chronic obstructive pulmonary disease

Exacerbations of chronic obstructive pulmonary disease (COPD) are a major problem worldwide and are usually the main indication for mechanical ventilation (MV), especially in the intensive care unit (ICU). The rate of weaning failure is also high and prolonged MV leads to complications of intubation. The goal is to wean these patients as soon as possible.

To determine the optimal time necessary to start the weaning process.

In an attempt to determine the length of MV and stay in the ICU, we compared the length of MV, weaning, reintubations and discharge during a 10 month period. This study included 122 patients on MV due to severe exacerbation of COPD who were not suitable for non-invasive ventilation. For each patient serial arterial blood gases were measured at admission and during hospitalization. PeCO2 (mixed expired CO2) was tested using a Datex S/5 instrument at follow-up.

The study population comprised all patients who required MV; of these 122, 108 were ventilated from 6 to 140 hours (mean 48 +/- 42), 9 needed more than 168 hours, and 5 died due to severe ventilation-associated pneumonia. No correlation was found between pH, PCO2 and length of MV; these findings did not contribute to evaluation of the patient's condition nor did they enable us to predict the length of treatment necessary.

Most of the patients (93%) ventilated for acute respiratory failure due to COPD required MV for only 6-90 hours.