Takahisa Goto

Comparison of inhalation inductions with xenon and sevoflurane

Background: Xenon is an odorless gas with low blood‐gas solubility coefficient and without occupational and environmental hazards. This investigation was performed to evaluate the speed of induction, and respiratory and cardiovascular reactions to inhalation induction with xenon compared to an equianesthetic concentration of sevoflurane.

Effect of xenon on autonomic cardiovascular control--comparison with isoflurane and nitrous oxide.

STUDY OBJECTIVES To clarify the effect of xenon on the autonomic nervous system by comparing similar effects of isoflurane and nitrous oxide. DESIGN Prospective, randomized study. SETTING Operating room at a university hospital. PATIENTS 39 ASA physical status I and II patients scheduled for general anesthesia. INTERVENTIONS Patients were randomly allocated into one of three groups and received one of the following inhalational anesthetics: 56% of xenon (Group X), 0.94% of isoflurane (Group I), or 70% of nitrous oxide and 0.15% of isoflurane (Group N). Phenylephrine (pressor test) and nicardipine (depressor test) were given to assess baroreflex sensitivity. MEASUREMENTS AND MAIN RESULTS Continuous blood pressure (BP) and electrocardiogram (ECG) were recorded before and during anesthesia to analyze heart rate (HR) variability and baroreflex sensitivity. Power spectrum of HR variability was calculated by fast Fourier transformation and power spectrum densities at low frequency (LF: 0.04-0.15Hz) and high frequency (HF: 0.15-0.40 Hz) were compared. Baroreflex sensitivity was calculated from the slope of regression for BP changes versus associated changes in R-R intervals. For HR variability, Group X showed lower power spectrum densities (ms(2).Hz(-1)) in LF and HF than did Group I (LF: 0.09 +/- 0.06 vs. 0.35 +/- 0.53; p < 0.05; HF: 0.40 +/- 0.34 vs. 0.98 +/- 0.68, p < 0.01). Group X had the lowest baroreflex sensitivity (ms.mmHg(-1)) via pressor test of the three study groups (Group X: 2.00 +/- 0.87, Group I: 3.53 +/- 2.14, Group N: 3.78 +/- 2. 17, p < 0.05). CONCLUSIONS Xenon depressed both sympathetic and parasympathetic transmission more than isoflurane at 0.8 MAC. Xenon was also suggested to be relatively vagotonic.

Xenon suppresses the hypnotic arousal in response to surgical stimulation

STUDY OBJECTIVE To evaluate the suppressive effects of xenon (Xe) on hypnotic arousal at skin incision. DESIGN Prospective, randomized study. SETTING Operating rooms at a university hospital. PATIENTS 35 ASA physical status I and II patients presenting for elective lower abdominal surgery. INTERVENTIONS Patients were randomly assigned to receive one of the following regimens: 1.3 minimum alveolar concentration (MAC) isoflurane, 1.3 MAC sevoflurane, 0.7 MAC Xe with 0.6 MAC sevoflurane, 1 MAC Xe with 0.3 MAC sevoflurane, or 0.7 MAC nitrous oxide (N2O) with 0.6 MAC sevoflurane (n = 7 each group). MEASUREMENTS AND MAIN RESULTS The bispectral index (BIS) was measured at baseline, during anesthesia, and after skin incision. BIS increased significantly at skin incision from the values noted during anesthesia in the sevoflurane and N2O groups, whereas it remained stable at incision in the other three groups (mean change in BIS: 0 +/- 9 for isoflurane, 15 +/- 8 for sevoflurane, 5 +/- 6 for 0.7 MAC Xe, 4 +/- 11 for 1 MAC Xe, and 9 +/- 5 for N2O). CONCLUSIONS Unlike N2O, Xe was able to suppress hypnotic arousal in response to surgical stimulation when administered with sevoflurane.

Cardiovascular effects of xenon and nitrous oxide in patients during fentanyl-midazolam anaesthesia

Xenon anaesthesia appears to have minimal haemodynamic effects. The purpose of this randomised prospective study was to compare the cardiovascular effects of xenon and nitrous oxide in patients with known ischaemic heart disease. In 20 patients who were due to undergo coronary artery bypass graft surgery, 30 min following induction of anaesthesia with fentanyl 30 µg.kg−1 and midazolam 0.1 mg.kg−1 but prior to the start of surgery, xenon or nitrous oxide 60% was administered for 15 min. The results showed that xenon caused a minimal decrease in the mean arterial pressure (from 81 (7) to 75 (8) mmHg, mean (SD)), but did not affect the systolic function of the left ventricle, as demonstrated by unchanged left ventricular stroke work index (LVSWI) and the fractional area change of the left ventricle (FAC) derived from transoesophageal echocardiography (TOE). However, in contrast, nitrous oxide was found to decrease the mean arterial pressure (from 81 (8) to 69 (7) mmHg), the LVSWI, and the FAC. The cardiac index, central venous and pulmonary artery occlusion pressures, systemic and pulmonary vascular resistances, and the TOE‐derived E/A ratio through the mitral valve were unchanged by xenon or nitrous oxide. We conclude that xenon provides improved haemodynamic stability compared with nitrous oxide, conserving the left ventricular systolic function.

Cost analysis of xenon anesthesia: a comparison with nitrous oxide-isoflurane and nitrous oxide-sevoflurane anesthesia

STUDY OBJECTIVE To determine the cost of xenon (Xe) anesthesia in relation to the anesthetic duration by conducting a cost analysis of this relatively expensive inhaled anesthetic. DESIGN Cost analysis based on the literature on Xe anesthesia. SETTING Anesthetic simulation based on data obtained in the operating rooms at a university hospital. PATIENTS A 40-year-old, ASA physical status I adult patient model weighing 70 kg, undergoing elective minor surgery with endotracheal intubation and mechanical ventilation. INTERVENTIONS Anesthesia was given in the following four techniques: 1) closed-circuit technique with Xe; 2) closed-circuit technique with nitrous oxide (N2O)-isoflurane; 3) semi-closed technique with N2O-isoflurane; and 4) semi-closed technique with N2O-sevoflurane. MEASUREMENTS AND MAIN RESULTS Cost of each anesthetic technique was compared in U.S. dollars. The cost of Xe anesthesia was consistently higher than that of N2O-isoflurane or N2O-sevoflurane (for 240-min anesthesia;

Prediction of difficult airway in school-aged patients with microtia.

356 with Xe,

Comparison of Acceleromyography and Electromyography in Vecuronium-induced Neuromuscular Blockade with Xenon or Sevoflurane Anesthesia

52 with closed-circuit N2O-isoflurane,

Is there a future for xenon anesthesia

94 with semi-closed N2O-isoflurane, and

Effect of xenon on endotracheal tube cuff

84 with semi-closed N2O-sevoflurane). The major cost of Xe anesthesia was a result of the cost of priming and flushing; the cost of Xe used for its anesthetic effects was comparable with the other semi-closed techniques after 240 minutes. CONCLUSIONS For Xe to be widely used in routine anesthesia, the methods of minimizing the amount of Xe necessary for priming and flushing must be developed.

Preoperative pulse wave velocity fails to predict hemodynamic responses to anesthesia and to surgical stimulation

Background: Because the ear and mandible develop from the first and second branchial arches and first branchial cleft, abnormalities of the ear may be a sign that intubation will be difficult. We hypothesized that children with microtia would have a greater incidence of difficult laryngeal visualization with conventional rigid laryngoscopy compared to those with normal facial anatomy.