• D J Murray, R B Forbes, D L Dull, and L T Mahoney.
• Department of Anesthesia, University of Iowa College of Medicine, Iowa City 52242.
• J Clin Anesth. 1991 Jan 1;3(1):14-9.

Study ObjectiveTo measure the hemodynamic changes produced by nitrous oxide (N2O) during halothane and isoflurane anesthesia in infants and children.DesignA repeated measures design in two groups of infants and small children.SettingOperating rooms at a university hospital.PatientsNineteen healthy unmedicated infants and small children (mean age 12 months) who required elective surgery.InterventionsPrior to anesthesia induction, cardiovascular measurements were recorded using pulsed Doppler and two-dimensional echocardiography. Following anesthesia induction with halothane (n = 10) or isoflurane (n = 9) in oxygen (O2) and air, anesthetic measures were stabilized at 1.0 minimum alveolar concentration (MAC) and cardiovascular measures were repeated. After 30% N2O was added to the 1.0 MAC anesthetic concentration, a third set of cardiovascular measurements was recorded. A final cardiovascular data set was measured 5 minutes following an increase in N2O concentration to 60%.Measurements And Main ResultsMean arterial pressure (MAP), cardiac index (CI), stroke volume (SV), and ejection fraction (EF) decreased similarly and significantly at 1.0 MAC halothane and isoflurane. Heart rate (HR) increased during isoflurane anesthesia but decreased during halothane anesthesia. The addition of N2O resulted in a decrease in HR, CI, and MAP when compared to 1.0 MAC levels of halothane or isoflurane; however, SV and EF were not significantly changed from levels measured during 1.0 MAC halothane or isoflurane.ConclusionsThe addition of N2O to halothane and isoflurane anesthesia in infants and children decreased HR. This decrease led to a decrease in cardiac output (CO). Unlike with adults, N2O did not produce cardiovascular signs of sympathetic stimulation in infants and children.

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