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

To determine whether upper airway obstruction 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 < 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 < 0.05). The presence of diminished peak and midinspiratory flow rates (p < 0.05) and patterns of extrathoracic obstruction (p < 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 < 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, correlated with structural changes observed during nasopharyngoscopy, and is useful in the early assessment of patients at risk for upper airway obstruction.