Large colon ischemia due to severe torsion causes uniformly distributed morphological changes throughout the affected colon. However, we hypothesize that during early hypoperfusion, microcirculatory impairment is not uniform among all regions of the colon. Thus, our goal was to study submucosal microcirculatory blood flow (smMBF) and oxygenation (smPO2) in the left dorsal (LDC) and ventral (LVC) colon. Five anesthetized horses (519±42 kg; mean±SD) were instrumented for hemodynamic monitoring. Through a celiotomy approach, the large colon was exteriorized and the LDC and LVC instrumented for smMBF (BPU) and smPO2 measurements using microprobes. Ischemia was induced by a 720° rotation of the large colon. After baseline (BL) recordings, smMBF, smPO2 and temperature were monitored throughout colonic torsion, ischemia, and reperfusion. Colonic venous O2 content (cvO2ct), pH, standard base excess, lactate, and blood gases were determined at baseline, 1 hr of ischemia, and post reperfusion. Data analysis included Friedman one-way ANOVA. Submucosal MBF decreased rapidly from BL by 100±0% and 96±5%, respectively in LDC and LVC, and PO2 decreased by 92±10% and 83±21%, respectively (P<0.05). Following detorsion of the colon smMBF and smO2 increased rapidly, reaching on average 132% and 40% higher values in the LVC as compared to LDC after 1 hr. The accumulated O2 debt was reversed into an O2 excess of 16±14 mmHg in the LVC but not LDC. In parallel acid-base parameters and cvO2ct improved significantly in ventral colonic venous blood (P<0.05). These pilot data provide evidence that microcirculation in the LDC does not recover as rapidly as in the LVC following reversal of colon torsion.
Submucosal microcirculatory blood flow and oxygen tension in an equine large colon torsion model.
ZARUCCO, Laura;
2004-01-01
Abstract
Large colon ischemia due to severe torsion causes uniformly distributed morphological changes throughout the affected colon. However, we hypothesize that during early hypoperfusion, microcirculatory impairment is not uniform among all regions of the colon. Thus, our goal was to study submucosal microcirculatory blood flow (smMBF) and oxygenation (smPO2) in the left dorsal (LDC) and ventral (LVC) colon. Five anesthetized horses (519±42 kg; mean±SD) were instrumented for hemodynamic monitoring. Through a celiotomy approach, the large colon was exteriorized and the LDC and LVC instrumented for smMBF (BPU) and smPO2 measurements using microprobes. Ischemia was induced by a 720° rotation of the large colon. After baseline (BL) recordings, smMBF, smPO2 and temperature were monitored throughout colonic torsion, ischemia, and reperfusion. Colonic venous O2 content (cvO2ct), pH, standard base excess, lactate, and blood gases were determined at baseline, 1 hr of ischemia, and post reperfusion. Data analysis included Friedman one-way ANOVA. Submucosal MBF decreased rapidly from BL by 100±0% and 96±5%, respectively in LDC and LVC, and PO2 decreased by 92±10% and 83±21%, respectively (P<0.05). Following detorsion of the colon smMBF and smO2 increased rapidly, reaching on average 132% and 40% higher values in the LVC as compared to LDC after 1 hr. The accumulated O2 debt was reversed into an O2 excess of 16±14 mmHg in the LVC but not LDC. In parallel acid-base parameters and cvO2ct improved significantly in ventral colonic venous blood (P<0.05). These pilot data provide evidence that microcirculation in the LDC does not recover as rapidly as in the LVC following reversal of colon torsion.
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