Abstract
Induced hypotension during anaesthesia can result in deterioration in gas exchange with increases in intrapulmonary shunting and physiological deadspace. Cardiovascular stability has been previously demonstrated with isoflurane-induced hypotension but the effects on gas exchange have not been carefully studied. We have examined the shunt fraction\(\left( {{{\dot QS} \mathord{\left/ {\vphantom {{\dot QS} {\dot QT}}} \right. \kern-\nulldelimiterspace} {\dot QT}}} \right)\) and physiological dead space to tidal volume ratio (Vd/Vt) before, during and following deliberate hypotension in twelve patients. Group I (n= 6) received an isofturane-oxygen-air mixture with an FrO2 of 0.5 while Group II (n = 6) received an isoflurane-oxygen mixture with an FiO2 of 1.0. Mean blood pressure was reduced from 76 ± 2 mmHg to 47 ±2 mmHg in the combined group. Neither\({{\dot QS} \mathord{\left/ {\vphantom {{\dot QS} {\dot QT}}} \right. \kern-\nulldelimiterspace} {\dot QT}}\) norVd/Vt changed significantly during the hypotensive state in either group. We conclude that isoflurane induced hypotension is associated with minimal pulmonary derangement.
Résumé
L’hypotension contrôiée pendant l’anesthésie peut amener une détérioration des échanges gazeux à cause de l’augmentation du shunt intra-pulmonaire el de l’espacemort physiologique. On a précédemment démontré la stabilité cardiovasculaire de l’hypotension induite avec l’isoflurane, mais ses effets sur les échanges gazeux n’ont pas été bien étudiés. Nous avons étudié la fraction du shunt\(\left( {{{\dot QS} \mathord{\left/ {\vphantom {{\dot QS} {\dot QT}}} \right. \kern-\nulldelimiterspace} {\dot QT}}} \right)\) et le rapport de l’espace-mort physiologique sur le volume courant (Vd/Vt) avant, pendant et apres l’hypotension contrôlée chez 12 patients. Le groupe I(n = 6) recevait isoflurane—O2-air pour obtenir une FrO2 =0.5 alors que le groupe II (n = 6) recevait isoflurane = O2, FrO = 1.0, La pression artérielle moyenne fut réduite de 76 ± 2 mmHg à 47 ± 2 mmHg dans les groupes combines. Ni le\({{\dot QS} \mathord{\left/ {\vphantom {{\dot QS} {\dot QT}}} \right. \kern-\nulldelimiterspace} {\dot QT}}\) ní leVd/Vt n’ont changeé de façon significative durant Vhypotension dans les deux groupes. Nous concluons quel ’hypotension induite par l’soflurane provoque peu de répercussions pulmonaires.
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Nicholas, J.F., Lam, A.M. Isoflurane-induced hypotension does not cause impairment in pulmonary gas exchange. Can Anaesth Soc J 31, 352–358 (1984). https://doi.org/10.1007/BF03015401
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DOI: https://doi.org/10.1007/BF03015401