Decreased mesenteric blood flow supplying retrosternal esophageal ileocoloplastic grafts during positive-pressure...

Esophageal replacement after esophagogastric injury caused by ingestion of lye may require the interposition of a retrosternal ileocolic graft. In this new anatomic situation, the mesenteric circulation supplying the graft is subjected to the intrathoracic pressure surrounding the graft. Thus, mesenteric blood flow supplying the graft may be impaired when intrathoracic pressure is increased during mechanical ventilation. This study was designed to evaluate the effect of increasing intrathoracic pressure by application of a positive end-expiratory pressure on mesenteric blood flow supplying esophageal ileocolic grafts. Eight cases were studied in the immediate postoperative period. Miniaturized implantable Doppler microprobes were sutured to the single artery supplying the graft and connected to an 8 MHz pulsed Doppler flowmeter. Two sets of measurements were successively performed with zero end-expiratory pressure ventilation and after application of a 15 cm water positive end-expiratory pressure. Positive end-expiratory pressure induces mean arterial pressure (-12%); p < 0.05) and cardiac output (-17%; p < 0.05) decrease. Mesenteric blood flow also decreases (-38%; p < 0.05) as did the mesenteric blood flow/cardiac output ratio, suggesting a potential mesenteric vasoconstriction assessed by mesenteric vascular resistance increase and mesenteric diastolic blood flow velocity decrease. These results suggest that, in the particular anatomic situation of the graft, increased intrathoracic pressure induces mesenteric blood flow decrease in relation to systemic hemodynamic alterations associated with perivisceral pressure increase. This change may be deleterious to graft perfusion.