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Is traditional fasting policy changing? Results of a Swiss survey on current practice

Hofer, C. K.; Zollinger, A.; Tucci, M.; van Gessel, E.; Alon, E.; Klaghofer, R.

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European Journal of Anaesthesiology: December 2002 - Volume 19 - Issue 12 - p 894-896


The traditional fasting policy (NPO, i.e. nulla per os, nil by mouth after midnight) has been challenged over the last two decades and more liberal recommendations and guidelines concerning preoperative fasting for adults and children (ASA I-II) have been published by different national societies in the Scandinavian countries, in Canada and in the USA [1,2].

In Switzerland, no specific national NPO guidelines have been established so far. Our survey was designed to determine whether the current NPO policy and practice of Swiss anaesthesiologists have changed according to international trends. In April 2000, questionnaires were sent to all 573 members of the Swiss Society of Anaesthesiology to assess the actual NPO practice in Switzerland. Questions were asked about general demographic data, NPO policy and practice guidelines. Replies from the blinded questionnaires were descriptively analysed via frequency distribution. The U-test compared data between the following groups: smaller versus larger institutions (< 10 000 versus > 10 000 anaesthetics per yr); paediatric versus paediatric and adult anaesthesia, in- versus outpatient practice, and public versus private hospitals. P < 0.05 was considered as statistically significant.

Two-hundred-and-forty-four members of the Swiss Society of Anaesthesiology responded to the questionnaire (response rate 44%); 19 questionnaires (retired anaesthesiologists and intensive care physicians) were excluded from the analysis. Of the responders, 68% reported on NPO guidelines for adults and 64% on NPO guidelines for children. Fifty per cent reported on changes in guidelines within the last 3 yr with increased patient satisfaction (55%) but without increased risk for pulmonary aspiration (100%). Only 10 of 235 respondents (4.5%) experienced a delay in the operating room schedules related to changed NPO guidelines.

For adults, 50% of the anaesthesiologists allowed clear liquids orally 2 h and 23% up to 4 h before the induction of anaesthesia. By contrast, only 13% said that their policy was to allow solid intake ('light breakfast', e.g. black tea and toast) 6 h before surgery. However, 3% of respondents shortened the NPO periods for solid intake below the recommended times. A more liberal approach to preoperative fasting times was observed in children. For older children (≥1 yr), 78% allowed clear liquids 2 h and 15% 4 h before surgery. For babies (<1 yr), 90% allowed clear liquids, 55% human breast milk and 41% non-human milk 2 h before surgery. Most anaesthesiologists permitted a more generous preoperative solid intake in children <1 yr than in older children, 21% even allow solid intake (muesli, porridge) < 6 h preoperatively in babies (Table 1).

Table 1
Table 1:
Current practice for preoperative fluid and solid intake. The number of respondents for any one question does not always equal the total respondents: some respondents did not answer all questions.

Clear water was the most widely accepted clear liquid preoperatively; 73% of the anaesthesiologists answering this question allow plain water 2-4 h preoperatively. Seven percent considered carbonated water acceptable during this period. Coffee with milk or orange juice was regarded as 'clear fluid' in the hours before induction of anaesthesia by a minority (Table 2).

Table 2
Table 2:
Types of fluid allowed within 2-4 h before operation.

Comparing different groups of institutions (smaller versus larger institutions, paediatric versus paediatric and adult anaesthesia, in- versus outpatient practice, public versus private hospitals), no statistical significant differences in NPO practice could be found (P = 0.3-0.9).

To date, most members of the Swiss Society of Anaesthesiology have an institutional policy in the form of written guidelines and half of them changed their policy and practice in the last 3 yr. They adapted new recommendations concerning liberalized fluid intake rather than those concerning preoperative solid intake. Fifty per cent of anaesthetists followed the guidelines of the ASA Task Force on Preoperative Fasting [2] for fluid intake in adults (clear fluid intake allowed up to 2 h before surgery). However, only 13% did so for solid intake (solid intake allowed up to 6 h, light breakfast up to 4 h before surgery). Several reasons may account for this finding. First, based on different investigations in the last decades demonstrating fast gastrointestinal passage of clear fluids, there is no controversy about clear fluid intake 2 h before induction of anaesthesia [2]. In contrast, residual gastric volume and content after solid intake may be increased depending on different solid food. However, a 'light breakfast', e.g. tea and toast, is supposed to go through the stomach within 4-6 h [3]. Second, changes in preoperative clear fluid consumption are easier to implement in daily practice than modifications in policy related to preoperative solid intake. Third, operating room schedules may be less impaired by patients who did not follow the NPO guidelines for fluid compared with solid intake. On the other hand, however, a minority of respondents even shortened the fasting periods for solid intake below the internationally recommended times. This may be an undesirable effect of currently changing guidelines and indicate a general uncertainty concerning these rules. The same is true for the definition of 'clear fluids', which apparently is not popular. NPO policy, not surprisingly, is less strictly handled for paediatrics compared with adults. Children do not tolerate well prolonged starving periods or thirst. Therefore, anaesthesiologists used to apply a more liberal policy in this age group for many years despite a higher prevalence of gastrointestinal regurgitation [4]. In our study, the ASA Guidelines [2] for clear fluids were followed by 78% of respondents in older children and by 90% in children <1 yr. In contrast to the ASA Guidelines (non-human breast milk allowed up to 6 h, human breast milk up to 4 h before operation), preoperative human or non-human milk intake was allowed more generously.

Swiss anaesthesiologists lacking specific national rules started to adapt their practice to internationally published guidelines. The results of this study concerning NPO policy are comparable with studies performed in countries with established national guidelines [5]. Consensus conferences on relevant topics for which evidence-based data are not available are important means to guide the international community of anaesthesiologists. However, in many cases, specific national guidelines may be desirable to underline current medico-legal issues in each country and to define important topics or limits in more detail.

C. K. Hofer, A. Zollinger

Institute of Anaesthesiology; Triemli City Hospital; Zurich, Switzerland

M. Tucci

Department of Anaesthesiology; University Hospital; Zurich, Switzerland

E. van Gessel

Department of Anaesthesiology; University Hospital; Geneva, Switzerland

E. Alon

Department of Anaesthesiology; City Hospital; Lugano, Switzerland

R. Klaghofer

Biostatistics, Division of Psychosocial Medicine; University Hospital; Zurich, Switzerland


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© 2002 European Academy of Anaesthesiology