Objective: To assess the effects of pentoxifylline posttreatment on hemodynamic variables and acute pulmonary injury in the rat intestinal ischemia-reperfusion (I-R) model, using a recently developed method of fluorescent intravital pulmonary videomicroscopy.
Design: Anesthetized male Sprague-Dawley rats were cannulated for measurement of mean arterial pressure, heart rate, cardiac output, arterial blood gas values, and hematocrit. Rats underwent isolation of the superior mesenteric artery for intestinal I-R (45 minutes of ischemia, 120 minutes of reperfusion) and right lateral thoracotomy for pulmonary videomicroscopy. Epi-illumination fluorescent videomicroscopy was used to quantitate leakage of intravascular fluorescently labeled albumin into alveoli, while hemodynamic variables were simultaneously recorded. In the treatment groups, pentoxifylline was administered after 30 minutes of intestinal ischemia. Data (mean +/- SEM) were recorded before and during intestinal ischemia and after reperfusion at 30-minute intervals.
Main outcome measure: The appearance of fluorescently labeled albumin into alveolar airspaces was quantitated off-line by computer and reported as the alveolar leak index.
Results: Intestinal I-R caused alveolar macromolecular leakage, marked by a 300% +/- 48% increase from baseline (P < .05) in the alveolar leak index. Intestinal I-R also produced systemic hemodynamic instability demonstrated by a decrease in the mean arterial blood pressure (-36% +/- 5% vs baseline, P < .05) and cardiac output (-42% +/- 6% vs baseline, P < .05), metabolic acidosis (final arterial pH of 7.17, P < .05 vs initial pH), and a 2.3-fold increase in the intravenous fluid requirement when compared with that in sham animals (P < .05). Treatment with pentoxifylline 30 minutes after intestinal ischemia attenuated pulmonary macromolecular leakage (P < .05 vs nontreated I-R) and reduced the decrease in cardiac output (-15% +/- 7% vs baseline, not statistically significant). Pentoxifylline treatment had no effect on the mean arterial blood pressure, heart rate, metabolic acidosis, or intravenous fluid requirement.
Conclusions: Pentoxifylline reduces alveolar capillary membrane injury and subsequent protein leakage and improves cardiac output when administered after 30 minutes of intestinal ischemia. These data suggest that pentoxifylline may be a possible candidate as a future therapy for acute pulmonary dysfunction. Further studies in human patients are necessary.