Upper airway function in burn patients. Correlation of flow-volume curves and nasopharyngoscopy

To determine whether upper airway dysfunction is detectable in patients with thermal injury, flow-volume curves were performed in 42 burn patients who were at risk for acute upper airway obstruction. Eighteen (42.9%) patients had abnormal inspiratory curves that were consistent with variable extrathoracic obstruction, a finding in only 8 (16%) of 50 nonburn control patients (p less than 0.01). A sawtooth pattern of the expiratory flow-volume curve was observed in 12 (28.6%) burn patients and in 5 (10%) control patients (p less than 0.05). The presence of diminished peak and midinspiratory flow rates (p less than 0.05) and patterns of extrathoracic obstruction (p less than 0.01) in burn patients correlated with the severity of anatomic injury visualized during fiberoptic nasopharyngoscopy and was more sensitive than the history and physical examination in detecting upper airway injury. Furthermore, flow-volume curve abnormalities were correlated (p less than 0.05) with the eventual need for endotracheal intubation. We conclude that physiologic dysfunction is often detectable using flow-volume curves in such burn patients, correlates with structural changes observed during nasopharyngoscopy, and is useful in the early assessment of patients at risk for upper airway obstruction.