Key result
Nitrous oxide, under normotensive or hypotensive conditions, neither influenced coronary arteriolar tone nor reduced or redistributed myocardial blood flow in a canine model.
Why the study?
Does nitrous oxide affect coronary microcirculation and hemodynamics in a canine heart model?
Does nitrous oxide affect coronary microcirculation and hemodynamics in a canine heart model?
In a canine model, nitrous oxide does not alter coronary arteriolar tone or myocardial blood flow under normotensive or hypotensive conditions.
Does not support changing nitrous oxide use in humans; leaves open clinical validation of coronary neutrality.
The safe use of nitrous oxide, in particular in patients with coronary artery disease, has been questioned. This study was designed to determine whether nitrous oxide directly affects global coronary hemodynamic variables and coronary arteriolar microvessels in the absence of changes of myocardial oxygen consumption. In dogs the effects of nitrous oxide were evaluated during normotension (NT, intravenous [IV] piritramid, nitrogen/oxygen; and NT/N2O, IV piritramid, nitrous oxide/oxygen) and during hypotension (MAP 60 mm Hg) (HT, IV piritramid, halothane, nitrogen/oxygen; and HT/N2O, IV piritramid, halothane, nitrous oxide/oxygen). The diameter of coronary arteriolar microvessels (range, 20-450 microns) was assessed by intravital fluorescence microscopy. Myocardial blood flow was determined by radioactive microspheres. Systemic and coronary hemodynamics, as well as arteriolar microvessel diameters, were comparable between NT and NT/N2O. During HT, nitrous oxide (HT/N2O) affected neither systemic nor coronary hemodynamics. Moreover, there was no obvious difference in the diameters of coronary microvessels between HT and HT/N2O. In conclusion, nitrous oxide, whether at normotensive or hypotensive conditions, neither influences coronary arteriolar tone nor reduces or redistributes myocardial blood flow.
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Vollmar et al. (1995) studied this question. Nitrous oxide vs. Nitrogen/oxygen was evaluated on Global coronary hemodynamic variables and coronary arteriolar microvessels diameter. Nitrous oxide, under normotensive or hypotensive conditions, neither influenced coronary arteriolar tone nor reduced or redistributed myocardial blood flow in a canine model.
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