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The temperature and humidity of inspired gases in infants using a pediatric circle system: effects of high and low‐flow anesthesia
Author(s) -
HUNTER TED,
LERMAN JERROLD,
BISSONNETTE BRUNO
Publication year - 2005
Publication title -
pediatric anesthesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.704
H-Index - 82
eISSN - 1460-9592
pISSN - 1155-5645
DOI - 10.1111/j.1460-9592.2005.01559.x
Subject(s) - medicine , humidity , anesthesia , fresh gas flow , relative humidity , ventilation (architecture) , mechanical ventilation , airway , meteorology , sevoflurane , physics
Summary Background: The effects of low‐flow anesthesia on the temperature and humidity of the inspired gas in infants during mechanical ventilation is unknown. This study was designed to evaluate the temperature and humidity of the inspired gas in infants using a pediatric circle absorber system with high and low fresh gas flow (HFGF and LFGF) anesthesia. Methods: Twenty infants participated in this observational, sequential, cross‐over study. Each infant was mechanically ventilated with a Kion Anesthesia Workstation, using a pediatric anesthesia circle circuit with both HFGF (6 l·min −1 ) and LFGF (0.6 l·min −1 ) technique. Airway temperature was recorded continuously at 16 sites throughout the breathing circuit. The relative humidity of the inspired gas was measured at the elbow connector adjacent to the CO 2 sampling line. Results: The mean airway temperatures of the inspired gas and the changes in mean airway temperatures throughout the breathing circuit during HFGF and LFGF did not differ significantly. The mean relative humidity of the inspired gas at steady state using a LFGF technique, 33.7 ± 3.6%, was approximately threefold greater than it was with a HFGF technique, 11.9 ± 5.1% ( P < 0.05). Conclusions: Low‐flow anesthesia with a pediatric circle system in infants neither increases the temperature of the inspired gas, nor achieves the minimum humidity of 50% reported to prevent ciliary damage, although the humidity during LFGF did increase threefold compared with HFGF. To maintain the temperature and humidity of the inspired gas during mechanical ventilation in infants, passive or active gas humidification should be used.