Oxygen consumption and carbon dioxide elimination in infants and children during anaesthesia and surgery
Lindahl, S.G.
British Journal of Anaesthesia 62(1): 70-76
1989
ISSN/ISBN: 0007-0912 PMID: 2492815 Document Number: 346472
Oxygen consumption (.ovrhdot.VO2, ml min-1) and carbon dioxide elimination (.ovrhdot.VCO2, ml min-1), minute ventilation (N.ovrhdot.VE), tidal volume (.ovrhdot.VT), rate of ventilation (f) and end-tidal carbon dioxide concentration (E'CO2%) were measured in 38 infants and children (body weights 3.6-25 kg). Four children (body weight < 5 kg) had congenital heart malformations and were studied during controlled mechanical ventilation, whereas the remainder (n = 34) who were healthy, breathed spontaneously. Anaesthesia was maintained with oxygen in air (F/O2 0.45) and halothane through a non-rebreathing circuit. Minute ventilation was measured by pneumotachography, E'CO2 with an in-line infra-red carbon dioxide meter and gas concentrations with a mass spectrometer. There were no differences in .ovrhdot.VO2 and .ovrhdot.VCO2 between children with and without heart disease. .ovrhdot.VO2 = 5.0 .times. kg + 19.8 (r = 0.94) and .ovrhdot.VCO2 to body weight by the equation: .ovrhdot.VCO2 = 4.8 .times. kg + 6.4 (r = 0.94). There were no differences between .ovrhdot.VO2 or .ovrhdot.VCO2 before and after the start of surgery. In 11 of 21 paietns weighing less than 10 kg, a reduced .ovrhdot.VCO2 was noted, giving respiratory quotients of less than 0.7. It is speculated that this age-dependent variation of .ovrhdot.VCO2 may result from partial inhibition of lipolysis in brown adipose tissue produced by halothane.