ARTERIAL OXYGEN TENSIONS MEASURED CONTINUOUSLY IN PATIENTS BREATHING 21% OXYGEN AND NITROUS OXIDE OR AIR

Changes in arterial oxygen tensions in nine anaesthetized patients during controlled ventilation with either 79% nitrous oxide in oxygen or air only, were measured continuously using an intra-arterial oxygen electrode. When the patients were ventilated with the mixture, there was a significant incre...

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Bibliographic Details
Published in:British journal of anaesthesia : BJA 1987-12, Vol.59 (12), p.1548-1553
Main Authors: SUGIOKA, K., CATTERMOLE, R.W., SEBEL, P.S.
Format: Article
Language:English
Subjects:
Adolescent
Adult
Aged
Air
Anesthesia
Anesthesia, General
Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy
Biological and medical sciences
Female
General anesthesia. Technics. Complications. Neuromuscular blocking. Premedication. Surgical preparation. Sedation
Humans
Male
Medical sciences
Middle Aged
Nitrous Oxide
Oxygen - blood
Partial Pressure
Respiration, Artificial
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Summary:Changes in arterial oxygen tensions in nine anaesthetized patients during controlled ventilation with either 79% nitrous oxide in oxygen or air only, were measured continuously using an intra-arterial oxygen electrode. When the patients were ventilated with the mixture, there was a significant increase in Pao2 of 2.74±1.08 kPa (P < 0.002) over control values obtained while the subjects were awake and breathing air spontaneously. Changing the inspired gas from nitrous oxide in oxygen to air while ventilation was held constant resulted in a significant decrease in Pao2 of 0.22±0.94 kPa (P < 0.001). However, these Pao2 values were not statistically significantly different from control values. We conclude that continuous accurate measurement of arterial oxygen tension is feasible provided that corrections are made in the electrode system for anaesthetic gases. We also found that the increase in PaO2 when 79% nitrous oxide in 21% oxygen was used, when compared with air, was lower than values proposed by previous investigators. The decrease in PaO2 when the inspired gas was changed back to room air was less than that found by others and there was no evidence of hypoxia when patients were ventilated on air alone after inspiring the mixture.
ISSN:0007-0912
1471-6771
DOI:10.1093/bja/59.12.1548