The use of nitrous oxide in anaesthetic practice: a second questionnaire survey.

Abstract

Following our questionnaire survey among consultant anaesthetists (Henderson et al. Anaesthesia 2002; 57: 1155–8), it was felt that a further survey should be carried out among junior anaesthetists to ascertain their views on the use of nitrous oxide in anaesthetic practice. Whilst we achieved a 75% response rate amongst consultants, we only had a 42% response rate amongst the trainee grades. This may reflect either the increased mobility of trainees so that fewer of the questionnaires were received, or that the trainee population are less interested in the topic of this questionnaire. However, a total number of 206 questionnaires were returned, which is not an insubstantial number. Of the valid questionnaires, 52% were male, 41% female and 7% did not state. Thus the sample had a much greater proportion of female anaesthetists than the original consultant questionnaire. The minimum number of years in clinical anaesthesia was 3 months; the maximum was 28 years, with a mean of 4.96 years. Generally the responses followed that of the consultant body, with 81% stating that they used nitrous oxide frequently and 19% occasionally. Over the last 3 years, 42% said that their use had stayed the same, with 55% stating it had decreased and 3% saying it had increased. An overwhelming majority (96%) stated that they avoided using nitrous oxide for certain operations, 4% stated they wouldn't avoid using nitrous oxide. Most trainees (74%) did not feel that pollution from nitrous oxide was a problem, but 79% did not feel that their use of nitrous oxide had been influenced by the effect of pollution on staff or other health implications. A small number of trainees (5%) felt that it would be acceptable to make nitrous oxide unavailable, 32% felt that it should be available on request and 62% felt that it should remain freely available. Thus, 38% felt that there should be some restriction in nitrous oxide availability, whereas only 20% of consultants felt there should be some restriction in its use. Half the trainees (50%) stated that all their anaesthetic machines had the provision of medical air, 48% said that some machines have medical air and 2% that none had provision. As to when medical air is used, 68% stated frequently, 30% occasionally and 2% never. When asked about their use of total intravenous anaesthesia (TIVA), 57% stated that over the last 3 years their use of TIVA has increased. When TIVA is used, 80% supplement with oxygen/air and 20% with oxygen/nitrous oxide. Generally the responses indicated that the majority of trainees who took part felt that nitrous oxide pollution in operating theatres was not a problem. A total of 18% have decreased their use as a result of health and pollution concerns; however, 14% considered nitrous oxide to be a problem but had not altered their practice. Further analysis was carried out on the female responses to determine whether there was a greater concern for health and pollution issues among this group. A total of 26% stated that this was the case, whereas 14% of the male responders felt there was a problem. A minority of females (18%) had changed their practice as a result of health and pollution issues and 13% felt that it was a problem but had not changed their practice. Despite the poorer response rate from the trainee grades to this questionnaire, the absolute number of responses was not negligible and there appears to be a greater concern about the effects of health and pollution generated from nitrous oxide amongst this group. A higher percentage of trainees than consultants (38% vs 20%) would like to see a restriction on the use of nitrous, again raising the question as to whether nitrous oxide should still be readily available on the anaesthetic machine?