DECREASED MESENTERIC BLOOD-FLOW SUPPLYING RETROSTERNAL ESOPHAGEAL ILEOCOLOPLASTIC GRAFTS DURING POSITIVE-PRESSURE BREATHING

Esophageal replacement after esophagogastric injury caused by ingestio n of lye may require the interposition of a retrosternal ileocolic gra ft. In this new anatomic situation, the mesenteric circulation supplyi ng the graft is subjected to the intrathoracic pressure surrounding th e graft. Thus, mesenteric blood flow supplying the graft may be impair ed when intrathoracic pressure is increased during mechanical ventilat ion. This study was designed to evaluate the effect of increasing intr athoracic pressure by application of a positive end-expiratory pressur e on mesenteric blood flow supplying esophageal ileocolic grafts. Eigh t cases were studied in the immediate postoperative period. Miniaturiz ed implantable Doppler microprobes were sutured to the single artery s upplying the graft and connected to an 8 MHz pulsed Doppler flowmeter. Two sets of measurements were successively performed with zero end-ex piratory pressure ventilation and after application of a 15 cm water p ositive end-expiratory pressure. Positive end-expiratory pressure indu ces 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, suggest ing a potential mesenteric vasoconstriction assessed by mesenteric vas cular resistance increase and mesenteric diastolic blood flow velocity decrease. These results suggest that, in the particular anatomic situ ation of the graft, increased intrathoracic pressure induces mesenteri c blood flow decrease in relation to systemic hemodynamic alterations associated with perivisceral pressure increase. This change may be del eterious to graft perfusion.