Effect of tracheostomy on pulmonary mechanics: An observational study

Abstract

Background:This study was undertaken to find out the effect of early tracheostomy on weaning from mechanical ventilation. Pulmonary mechanics and arterial blood gases were assessed before and after tracheostomy in patients with severe head injury (Glasgow coma score < 8) requiring prolonged mechanical ventilation.Patients and Methods:The study included 20 mechanically ventilated patients of either sex between 20 and 45 years of age, who had suffered brain injury due to head trauma during admission (Glasgow coma scores of < 8). Mean airway pressure, peak airway pressure, plateau pressure, PaO2 and PaCO2 were measured 24 h before and after tracheostomy. Static and dynamic compliances were calculated.Results:Plateau airway pressures were not affected by tracheostomy, but peak airway pressure was reduced (29.90 ± 3.21 cm H2O before tracheostomy versus 24.30 ± 1.83 cm H2O after tracheostomy, P < 0.001). Dynamic compliance, but not static compliance, was improved by tracheostomy. Tracheostomy did not affect PaCO2, but it improved PaO2 (83.09 ± 5.99 mmHg before versus 90.84 ± 5.61 mmHg after, P < 0.001).Conclusions:The work of breathing through a tracheostomy tube may be less than through an endotracheal tube of same internal diameter.