Early biochemical markers of inflammation in a swine model of endotracheal intubation.

BACKGROUND: A common complaint after endotracheal tube use is sore throat, which may be due to abrasion, ischemia-reperfusion injury, or an inflammatory reaction. Few studies have evaluated localized tracheal inflammation as part of the response to intubation.
METHODS: Inflammation of the trachea due to intubation was assessed in a swine model by following indicators of inflammation over time in the tracheal lumen. Repeated tracheal lavages proximal to the endotracheal tube cuff were performed, and recovered lavage was analyzed for cells, protein, lactate dehydrogenase, and cytokines.
RESULTS: The baseline tracheal lavage samples contained 18% polymorphonuclear cells. These cells increased rapidly to 43% by 1 h. The polymorphonuclear cell increase from baseline was significant at 1, 2, and 4 h (P < 0.01) after intubation. Tumor necrosis factor alpha, interleukin 1beta, interleukin 6, and interleukin 8 increased over time, but only interleukin 6 increased significantly (P < 0.01). Interleukin 6 was not detected at baseline or 1 h, but was detected at 2 h and increased significantly by 4 h. Neither lavage protein concentration nor lactate dehydrogenase activity increased over time.
CONCLUSIONS: These results demonstrate that inflammation does occur during tracheal intubation, even when markers suggest minimal tracheal damage. The dramatic elevation in polymorphonuclear cells, along with the increase in interleukin 6, suggests an inflammatory response to the endotracheal tube itself or to some aspect of the intubation process. A more complete understanding of the response of the tracheal tissues is important in improving the treatment of intubated patients.