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Atelectasis and gas exchange impairment during enflurane/nitrous oxide anaesthesia
Author(s) -
Gunnarsson L.,
Strandberg A.,
Brismar B.,
Tokics L.,
Lundquist H.,
Hedenstierna G.
Publication year - 1989
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1989.tb02981.x
Subject(s) - medicine , nitrous oxide , enflurane , anesthesia , atelectasis , halothane , lung
The development of atelectasis and effects on gas exchange during enflurane anaesthesia in nitrogen/oxygen or nitrous oxide/oxygen (inspired oxygen fraction 0.4) were studied in 16 lung‐healthy patients (mean age 49 years). Awake, no subject displayed atelectasis as assessed by computed x‐ray tomography of the thorax. Pulmonary gas exchange, studied by multiple inert gas elimination technique, and blood gases were normal. After 10 min of enflurane anaesthesia in nitrogen/oxygen, 14 of 16 subjects had developed atelectasis. After 30 min of enflurane anaesthesia in nitrogen/oxygen or nitrous oxide/oxygen, all patients had developed atelectasis, and a further increase was observed after 90 min of anaesthesia to approximately 5% of the intrathoracic area. There was no difference between the two anaesthesia groups. In the nitrogen group, shunt rose to a maximum of 5.8% at 30 min of enflurane anaesthesia, with a significant reduction to the initial anaesthesia level after 90 min of anaesthesia (3.4%). Perfusion of poorly ventilated lung regions (low VA/Q) averaged 4–5% and did not vary significantly during the anaesthesia. In the nitrous oxide group, shunt increased to 6.3% after 90 min of anaesthesia, and there was a parallel decrease in perfusion of low VA/Q regions. The findings suggest that besides prompt collapse of lung tissue during induction of anaesthesia, absorption of gas from closed‐off or poorly ventilated regions takes place and further increases the atelectatic area.