title: Isoflurane-induced hypotension does not cause impairment in pulmonary gas exchange.
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 (QS/QT) 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 isoflurane-oxygen-air mixture with an FIO2 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 QS/QT nor VD/VT changed significantly during the hypotensive state in either group. We conclude that isoflurane induced hypotension is associated with minimal pulmonary derangement.
mesh_terms: D000328:Adult; D000771:Anesthesia, Intravenous; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007023:Hypotension, Controlled / Q000009:adverse effects*; D007530:Isoflurane / Q000009:adverse effects / Q000494:pharmacology*; D008738:Methyl Ethers / Q000494:pharmacology*; D008875:Middle Aged; D011659:Pulmonary Gas Exchange / Q000187:drug effects*; D011897:Random Allocation
chemical_list: D008738:Methyl Ethers; D007530:Isoflurane