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The rate of alveolar‐capillary uptake of sevoflurane and nitrous oxide following anaesthetic induction
Author(s) -
Peyton P. J.,
Fortuin M.,
Robinson G J. B.,
StuartAndrews C.,
Pierce R.,
Thompson B. R.
Publication year - 2008
Publication title -
anaesthesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.839
H-Index - 117
eISSN - 1365-2044
pISSN - 0003-2409
DOI - 10.1111/j.1365-2044.2007.05355.x
Subject(s) - nitrous oxide , sevoflurane , medicine , anesthesia , arterial blood , ventilation (architecture) , minimum alveolar concentration , breathing , capillary action , partial pressure , respiratory rate , oxygen , heart rate , blood pressure , chemistry , materials science , mechanical engineering , organic chemistry , engineering , composite material
Summary The rate of anaesthetic gas uptake from the breathing system has been extensively measured, but this does not reflect the true rate of early gas uptake by pulmonary blood, which drives inhalational induction of anaesthesia. In eight patients undergoing coronary bypass surgery, we measured the rate of alveolar‐capillary uptake of anaesthetic gases up to 30 min following introduction of 0.5% sevoflurane and 33% nitrous oxide using the reverse Fick method, in which blood partial pressures were measured using a headspace equilibration technique. Simultaneous measurements of gas uptake from the breathing system were made by indirect calorimetry. Measured rates of sevoflurane and nitrous oxide uptake from the breathing system agreed well with previously described formulae when adjusted for inspired concentration. The time course of alveolar‐capillary gas uptake followed a characteristic rising curve peaking at 3–4 min and then exponentially declining, and for nitrous oxide was significantly higher than previously estimated.