Author/Editor		Jakovljević, Miroljub
Title		Heart rate, blood pressure and respiration variability during inhalation of subanaesthetic levels of nitrous oxide
Type		monografija
Place		Portsmouth
Publisher		University of Portsmouth
Publication year		2001
Volume		str. 94
Language		eng
Abstract		Based on the observations of Galletly et al. (1993), it was hypothesised that it may be possible to quantify the effects of inert gas narcosis by assessing heart rate variability. As a prelude to a study examining the dose-dependent effects of the partial pressure of nitrogen (PNZ) on heart rate variability, we examined the effect of different levels of inert gas narcosis on heart rate variability, blood pressure variability and respiratory variability, as induced by inhalation of normoxic mixtures containing I S% or 30% nitrous oxide (Nz0). Subjects: ten healthy male subjects participated in the study. Their mean+-SD (range) age was 26.9+-6.3 (20-39) yr, height was 178.7±4.6 (168-183) cm, and weight was 79.6+-7,1 (69-92.5) kg. Protocol: electrocardiograms (ECG), arterial blood pressure (ABP) and inspired tidal volume (VI) were recorded under three experimental conditions, each lasting 20 minutes. During all conditions, subjects rested in a supine position. During the first 20 minute period, subjects inspired air, whilst during the subsequent two 20 minute periods they inspired normoxic mixtures containing 15% and 30% N20. The order in which subjects received the two N20 mixtures was the same for all subjects. The analysis of the recorded variables was conducted during the last 5 minutes of each session. Instrumentation: continuous ECG were obtained from pre-gelled electrodes positioned in a lead II arrangement and recorded on magnetic tape using an FM tape recorder. ABP was monitored with a Finapres blood pressure monitor. Subjects breathed through a Hans Rudolph respiratory valve and VI was monitored with a turbine ventilation module. Subjects inspired the different breathing mixtures via Collins respiratory tubing which had been humidified by passing the gas through a water bath at room temperature (21-25degreesC). (Abstract truncated at 2000 characters)
Descriptors		INERT GAS NARCOSIS NITROUS OXIDE HEART RATE BLOOD PRESSURE TIDAL VOLUME ADULT ELECTROENCEPHALOGRAPHY ADMINISTRATION, INHALATION SUPINE POSITION DOSE-RESPONSE RELATIONSHIP, DRUG ANALYSIS OF VARIANCE