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A WinChart review of 10,000 anaesthetics
increasing mean inspired nitrous oxide concentration in theatre does not increase mean nausea scores in recovery
Robert Grace1,2, John Archdeacon1,2, Peter Toth3, Phillip McSharry4,Michael McManus1,2
1Department of Anaesthesia, Intensive Care and Perioperative Medicine, Cairns Base Hospital, Cairns, Queensland, Australia
2Honorary SeniorLecturer, James Cook University Medical School, Townsville, Queensland, Australia
3Medtel Australia
4CodeSmiths, Sydney, Australia
Background: The WinChart® electronic record keeping system provides a powerful tool with which to analyze large numbers of anaesthetics. Our department has been keeping electronic anaesthetic records since 2003 and now has the capacity to examine large numbers of these records. We present one of the first studies using WinChart® and one of the first ever mega anaesthetic studies. We examine whether increasing mean inspired nitrous oxide in theatre increases the mean nausea score in recovery.
Methods: This is a retrospective review. All available anaesthetic records where the mean inspired nitrous oxide during the case was greater than 10% and less than 75% were examined. Only those records where the nausea score in recovery was not 'null' were included. The mean nausea score in recovery for each anaesthetic was then determined. The mean inspired nitrous oxide was then plotted against the mean nausea score in recovery for each case.
Results: 10,917 anaesthetics fitted our criteria. Values for the mean inspired nitrous throughout the case ranged from 10.2% to 73.7%,(mean 51.2% +/- 11.3%). Mean nausea scores ranged from 0 to 3,(mean 0.06+/-0.2),(median 0). There was no correlation between the mean inspired nitrous during the case and the mean nausea score in recovery.(Correlation co-efficient = 0.0027)
Conclusion: The WinChart® electronic record keeping system is an exciting research tool enabling large studies in anaesthesia to be undertaken. Increased mean inspired nitrous oxide did not correlate with increased mean nausea scores in recovery in more than 10,000 cases. Extrapolation of this result suggests that the use of nitrous oxide does not lead to increased nausea.