Preoperative Fasting Time

Is the Traditional Policy Changing? Results of a National Survey

Abstract

Several papers in the 1980s questioned the wisdom of withholding clear liquids for more than 3 h before elective surgery.Furthermore, recent papers have suggested relaxing the current NPO after midnight (Latin: Nulla per os; or "nothing by mouth") practice in children and adults. To see whether the policy and practice regarding NPO status before elective surgery have changed in the United States, we performed a national survey. In November 1992, 300 questionnaires were mailed to the chairpersons of 114 university anesthesiology programs and the medical directors of 186 randomly selected, free-standing ambulatory surgery centers. Seventeen simple questions were asked regarding their NPO policy and practice guidelines before elective operations. Replies were tabulated, and the data were descriptively analyzed via frequency distribution. We received 191 replies, 85 from the university programs and 106 from the free-standing units (75% and 57% response rates, respectively) from all six time zones of the United States. Fifty-seven percent of the responders stated that they had revised their NPO policy during the last 3 yr, whereas 39% reported that they had not changed their NPO policy. One hundred percent of the respondents who allowed clear liquids considered water to be acceptable for adults, whereas 94% considered water acceptable in the pediatric population. Eighty-one percent of the responders denied the use of routine prophylaxis for acid aspiration. None of the responders reported an adverse outcome which could be attributable to the recent change in the NPO guidelines. On a related question, 16% of all the respondents stated that they would cancel the operation if a patient arrived for an elective outpatient surgical procedure after consuming coffee with cream 2 h before operation. In conclusion, our survey revealed that 69% of anesthesiologists in the United States have either changed their NPO policy or are flexible in their practice in allowing clear liquids before elective operation in children and 41% have done so for adult patients. The most frequently allowed clear liquids in the adult and pediatric population were water and apple juice. None of the respondents reported any medical adverse event associated with the institution of a flexible NPO policy.

(Anesth Analg 1996;83:123-8)

Historically, adult patients have fasted 8-12 h before surgery to reduce the volume of gastric contents and the risk of aspiration pneumonitis. Thus, NPO after midnight (Latin: Nulla per os; or "nothing by mouth") is a time-honored preoperative order. However, long fasting prior to an elective operation is not only uncomfortable for the patient but has detrimental effects. It causes thirst, hunger, irritability, noncompliance, and resentment in adult patients ^[1]. Prolonged fasting is especially deleterious in children, since it may also produce dehydration, hypovolemia, and hypoglycemia ^[2,3].

During the last 10 yr, several papers have challenged the traditional practice of fasting presurgical patients for 8 h or more ^[4-8]. Studies have shown that ingested clear liquids leave the stomach in less than 2 h in both children and adults ^[9]. Other studies have shown that the ingestion of preoperative clear liquids promotes gastric emptying and is associated with minimal change in gastric pH ^[10-12]. Recently the authors of several editorials suggested that a relaxation of the traditional NPO policy may be safe as well as humane ^[14-16]. Despite these publications, we postulated that most anesthesiologists have not changed their NPO policy to allow clear liquids for patients scheduled for elective outpatient procedures. With this in mind, a survey to define the current NPO policy and practice standards among anesthesiologists in the United States was designed.

Methods

To test the hypothesis, a questionnaire was prepared in November 1992 to assess the status of NPO practice across the United States. The goal was to reach a total of 300 facilities that perform all types of outpatient surgery. Thus, questionnaires were mailed to the 114 chairpersons of all university anesthesiology programs in the United States and 186 medical directors of free-standing ambulatory surgery facilities in the United States, randomly selected from about 2000. Each recipient was asked to complete a simple three-page questionnaire that consisted of 17 questions regarding demographics, NPO policy, practice guidelines, and any adverse outcomes. In April of 1993, a second questionnaire was submitted to the facilities and free-standing ambulatory centers who had not responded to our first questionnaire. Replies were tabulated and the data were descriptively summarized via frequency distributions.

Results

Overall, 64% or 191 anesthesiologists responded to the questionnaire. The response rates were 75% among the university programs and 55.5% among the free-standing facilities. No regional differences in NPO practices were identified Table 1. Fifty-seven percent of the respondents stated that they had changed their NPO policy within the last 3 yr, whereas 39% of the respondents reported that they had not revised their policy Table 2.

Table 1: Demographic Data of Respondents

Table 2: Date of Last Revision of NPO Policy

For adults, 59% of the respondents reported they abide by the traditional NPO policy (i.e., NPO after midnight; Table 3). Twenty-four percent allow clear liquids up to 4 h prior to surgery in the adult population and 17.5% of the anesthesiologists were flexible in their NPO practice policy. Thus, overall, 41% of the anesthesiologists were either flexible or would allow clear liquids up to 4 h prior to elective ambulatory procedures in the adult patient, whereas 68% of the anesthesiologists reported this for the ambulatory pediatric population. Thirty-one percent of the anesthesiologists reported no change in their NPO policy or practice in the pediatric patient population.

Table 3: Current NPO Guidelines for Clear Liquid Prior to Elective Outpatient Surgery

The positive respondents were queried as to what type of clear liquids they allowed up to 4 h prior to the induction of anesthesia. For the respondents who allowed clear liquids, 100% considered water to be an acceptable clear fluid for adults, yet only 94% considered it acceptable in the pediatric population Table 4. More than 90% of the respondents allowed apple juice for adults and children. When anesthesiologists allowed fluids 2-4 h prior to induction of anesthesia, 46% limited the amount of fluids prior to the elective surgical procedure. Only 19% of the anesthesiologists sampled used routine aspiration prophylaxis for elective outpatients. None of the anesthesiologists reported any adverse outcomes associated with their policy change.

Table 4: Types of Clear Liquid Positive Responders Would Allow Within 2-4 h

All respondents were asked to address the ideal management for a hypothetical case: A 31-yr-old ASA grade I adult female patient presents to your facility for an elective outpatient diagnostic laparoscopic procedure. The patient reported consuming coffee with cream and sugar 2 h earlier. Sixteen percent of the respondents stated that they would cancel the procedure, while 20% would proceed without modifications. However, 64% of the respondents reported that they would proceed with a modification in the anesthetic technique.

Discussion

The fact that the stomach handles emptying of solids and liquids differently has been known for more than 100 years from the work of William Beaumont ^[17]. Despite this knowledge, physicians lumped both solids and liquids together in the standard preoperative order: "nothing by mouth after midnight" the day before surgery. Thus, NPO after midnight became a common medical practice.

With the increasing use of outpatient surgery, children were no longer admitted to the hospital the day before the operation. It was difficult for parents to follow preoperative NPO orders and deprive their child of food or drink for long periods of time (especially for an afternoon operation). Some anesthesiologists empathized with these parents and started to conduct studies to evaluate whether the traditional NPO guidelines were valid for clear liquids. The results of these studies culminated in editorials in three leading anesthesia journals ^[14-16].

Sixty-four percent of the 300 anesthesiologists surveyed responded to our questionnaire. This reflects a good sample and response rate, given the frequent requests to complete questionnaires and the other demands on the time of these physicians. Our survey shows that the majority of the anesthesiologists across the country have already changed their NPO guidelines for children and have relaxed it significantly for adults. The changed attitude of the anesthesiologists toward a typical case scenario that we presented, i.e., a patient who consumed coffee in the morning, is revealing. The responses from the academic centers were very similar to the responses from the surgical centers.

It was interesting to note that the anesthesiologists surveyed were more likely to have changed their NPO policy or were flexible in allowing clear liquids before elective operations for children (69%) than for adults (41%). The relaxation of the NPO policy in the pediatric population may reflect the well-documented adverse events associated with a long preoperative fast: irritability, hypoglycemia, hypotension, hypovolemia, and dehydration ^[1,2]. The inertia in changing the NPO policy in the adult population may very well be due to the lack of adverse events due to fasting, i.e., the perception that it is merely uncomfortable, as opposed to its being unsafe, in this patient population. The known benefits of increased patient satisfaction, decreased anxiety, and less thirst are somewhat overlooked in this population for fear of potential acid aspiration. Another reason for the sluggish change in the adult population may be the avoidance of potential administrative problems: 1) the surgical procedure might occur earlier due to scheduling changes, 2) delay due to scheduling conflicts or the patient has not fasted for the perceived length of time, and 3) the procedure may be canceled due to the patient's consumption of the inappropriate clear liquid.

The most frequently allowed clear liquids in the adult population are water, apple juice, black coffee, and tea. In the pediatric population, water, apple juice, and carbonated beverages are allowed most commonly. We suspected that anesthesiologists who allowed clear liquids before surgery might use routine acid prophylaxis in elective operations as a preventative measure to thwart acid aspiration. However, we were surprised to find that 81% of the respondents denied this as a routine practice. It is important to note that if confusion exists among physicians, then patients may not be able to identify appropriate clear fluids prior to surgery. What the anesthesiologist considers to be an inappropriate use of clear fluids or lack of compliance by the patient may simply be the actions of a patient who thinks that he or she was following instructions. To avoid confusion, it might be advantageous for anesthesiologists to come to some consensus as to which fluids constitute a clear liquid, while keeping the list short and simple.

Many anesthesiologists still abide by the traditional NPO policy in adults, perhaps because it is simple, possibly ensures compliance, and decreases the potential for any adverse outcomes. For the anesthesiologists surveyed who adopted or were flexible in their NPO policy, the only adverse problem noted was nonmedical. They cited the economic impact of a delay in the operating room schedule and the potential for cancellation of the surgical procedure when the patient consumed what was perceived as being the wrong clear fluid. None of the respondents reported an adverse medical outcome associated with the modified policy. Inasmuch as only the directors of free-standing ambulatory facilities and university anesthesiology residency programs were sampled, it is certainly possible that there may have been adverse events with the policy change of which they were unaware. However, it was assumed that the director of the facility was the standard bearer for the institution, and would also be the most knowledgeable about quality, policy, and adverse outcomes, which tend to be easy to remember. Thus, in regard to adverse outcomes, this study is totally dependent on the memory of the anesthesiologist who actually completed the form. Also, this study was limited to anesthesiologists who have a freestanding ambulatory facility or who are in university settings. Specific inquiry about NPO policy and subsequent adverse events of anesthesiologists who practice in community hospitals was not obtained. The NPO policy and practice of anesthesiologists in community hospitals may be quite different from or similar to the trends that we are reporting.

Our survey, which was concluded about two years ago, revealed that many anesthesiologists either have already changed or relaxed their NPO guidelines for elective surgery or are in the process of doing so for adults. The preponderance of anesthesiologists are also willing to change the policy for children than for adults. Table 5

Table 5: Appendix: NPO Questionnaire (Please check as many options as appropriate)