Does preoperative fasting and the use of pharmacologic agents reduce the risk of pulmonary aspiration in healthy patients undergoing elective procedures?
These practice guidelines recommend a 2-hour fasting period for clear liquids and a 4-hour fasting period for breast milk prior to elective procedures to minimize the risk of pulmonary aspiration in healthy patients.
Developed by the Task Force on Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration: Mark A. Warner, M.D. (Chair), Rochester, Minnesota; Robert A. Caplan, M.D., Seattle, Washington; Burton S. Epstein, M.D., Washington, DC; Charles P. Gibbs, M.D., Denver, Colorado; Candace E. Keller, M.D., M.P.H., Hattiesburg, Mississippi; Jessie A. Leak, M.D., Fayetteville, North Carolina; Roger Maltby, M.B.B.S., Calgary, Alberta, Canada; David G. Nickinovich, Ph.D., Bellevue, Washington; Mark S. Schreiner, M.D., Philadelphia, Pennsylvania; Chris M. Weinlander, M.D., Appleton, Wisconsin.Click on the links below to access all the ArticlePlus for this article.Please note that ArticlePlus files may launch a viewer application outside of your web browser.PRACTICE guidelines are systematically developed recommendations that assist the practitioner and patient in making decisions about health care. These recommendations may be adopted, modified, or rejected according to clinical needs and constraints.Practice guidelines are not intended as standards or absolute requirements. The use of practice guidelines cannot guarantee any specific outcome. Practice guidelines are subject to periodic revision as warranted by the evolution of medical knowledge, technology, and practice. The guidelines provide basic recommendations that are supported by analysis of the current literature and by a synthesis of expert opinion, open forum commentary, and clinical feasibility data (Appendix).The purposes of these Guidelines are to enhance the quality and efficiency of anesthesia care, stimulate evaluation of individual practices, and reduce the severity of complications related to pulmonary aspiration of gastric contents, should it occur. Enhancements in the quality and efficiency of anesthesia care include, but are not limited to, the cost-effective utilization of perioperative preventive medication, increased patient satisfaction, avoidance of delays and cancellations, decreased risk of dehydration or hypoglycemia from prolonged fasting, and the minimization of perioperative morbidity. Complications of aspiration include, but are not limited to, aspiration pneumonia, respiratory disabilities, and related morbidities.Prevention of pulmonary aspiration is part of the larger process of preoperative evaluation and preparation of the patient. The Guidelines specifically focus on preoperative fasting recommendations, as well as recommendations regarding the administration of pharmacologic agents to modify the volume and acidity of gastric contents during procedures in which upper airway protective reflexes may be impaired.Airway management techniques that are intended to reduce the occurrence of pulmonary aspiration are not the focus of these Guidelines. For example, a rapid-sequence induction/endotracheal intubation technique or awake endotracheal intubation technique may be useful to prevent this problem during the delivery of anesthesia care. The Guidelines do not address the selection of anesthetic technique.The intended patient population is limited to healthy patients of all ages undergoing elective procedures. The Guidelines do not apply to patients who undergo procedures with no anesthesia or only local anesthesia when upper airway protective reflexes are not impaired, and no risk factors for pulmonary aspiration are apparent. The Guidelines are not intended for women in labor.The Guidelines may not apply to or may need to be modified for patients with co-existing diseases or conditions that might affect gastric emptying or fluid volume (e.g., pregnancy, obesity, diabetes, hiatal hernia, gastroesophageal reflux disease, ileus or bowel obstruction, emergency care, or enteral tube feeding) and patients in whom airway management might be difficult. Anesthesiologists and other anesthesia providers should recognize these conditions and minimize the opportunity for regurgitation and pulmonary aspiration.The Guidelines are intended for use by anesthesiologists and other anesthesia providers. They also may serve as a resource for other health care professionals who advise or care for patients who will receive anesthesia care during procedures. Anesthesia care during procedures is defined as general anesthesia, regional anesthesia, or sedation/analgesia (i.e., monitored anesthesia care). Throughout these Guidelines, the term “preoperative” should be considered synonymous with “preprocedural”, as the latter term relates to procedures commonly not considered to be operations.The ASA appointed a Task Force of 10 members to (a) review the published evidence;(b) obtain consultant opinion from a representative body of anesthesiologists, nurse anesthetists, anesthesiology assistants, perioperative nurses, surgeons, gastroenterologists and other internists, dentists and oral surgeons, ophthalmologists, psychiatrists, emergency medicine physicians, and practice management staff personnel; and (c) build consensus within the Task Force. The Task Force members consisted of anesthesiologists in both private and academic practices from various geographic areas of the United States and Canada and methodologists from the ASA Ad-Hoc Committee on Practice Parameters.The Task Force met its objective in a five-step process. First, original published research studies relevant to these issues were reviewed and analyzed. Second, Consultants from around the world who practice or work in various settings (e.g., academic and private practice) were asked to (a) participate in a survey of their impressions of the effectiveness of various fasting and pharmacologic interventions to decrease the risks of perioperative pulmonary aspiration, and (b) review and comment on the initial draft report of the Task Force. Third, the Task Force held an open forum at a major national anesthesia meeting to solicit input on its draft recommendations from attendees of the meeting. Fourth, all available information was used to build consensus within the Task Force on the recommended guidelines that follow. Finally, the Consultants were surveyed to assess their opinions on the feasibility of implementing the Guidelines.Evidence-based guidelines are developed by a rigorous analytic process. To assist the reader, the Guidelines make use of several descriptive terms that are easier to understand than the technical terms and data that are used in the actual analyses. These descriptive terms are defined below:The following terms describe the availability of scientific evidence in the literature.Insufficient: There are too few published studies to investigate a relationship between a clinical intervention and clinical outcome.Inconclusive: Published studies are available, but they cannot be used to assess the relationship between a clinical intervention and a clinical outcome because the studies either do not meet predefined criteria for content as defined in the “Focus of the Guidelines,” or do not meet research design or analytic standards.Silent: There are no available studies in the literature that address a relationship of interest.The following terms describe the strength of scientific data when sufficient literature is available.Supportive: There is sufficient quantitative information from adequately designed studies to describe a statistically significant relationship (P<0.01) between a clinical intervention and a clinical outcome, using the technique of meta-analysis.Suggestive: There is enough information from case reports and descriptive studies to provide a directional assessment of the relationship between a clinical intervention and a clinical outcome. This type of qualitative information does not permit a statistical assessment of significance.Equivocal: Qualitative data have not provided a clear direction for clinical outcomes related to a clinical intervention and (1) there is insufficient quantitative information or (2) aggregated comparative studies have found no quantitatively significant differences among groups or conditions.The following terms describe survey responses from Consultants for any specified issue. Responses are weighted as agree =+1, undecided = 0 or disagree =-1.Agree: The average weighted responses must be equal to or greater than +0.30 (on a scale of -1 to 1) to indicate agreement.Equivocal: The average weighted responses must be between -0.30 and +0.30 (on a scale of -1 to 1) to indicate an equivocal response.Disagree: The average weighted responses must be equal to or less than -0.30 (on a scale of -1 to 1) to indicate disagreement.There is insufficient published evidence to evaluate the effect of a preoperative assessment (e.g., history, physical examination, survey/interview) on the frequency or severity of pulmonary aspiration of gastric contents during the perioperative period. The Consultants and the Task Force agree that a preoperative assessment may be associated with improved outcome related to the prevention of perioperative pulmonary aspiration of gastric contents.Recommendations: A review of pertinent medical records, a physical examination, and patient survey or interview should be performed as part of the preoperative evaluation. The history, examination, and interview should include pertinent assessment of gastroesophageal reflux disease, dysphagia symptoms, or other gastrointestinal motility disorders, potential for difficult airway management, and metabolic disorders (e.g., diabetes mellitus) that may increase the risk of regurgitation and pulmonary aspiration. Patients should be informed of fasting requirements and the reasons for them sufficiently in advance of their procedures. Verification of their compliance with the fasting requirements should be assessed at the time of their procedures. When the following fasting guidelines are not followed, the practitioner should compare the risks and benefits of proceeding, with consideration given to the amount and type of liquids or solids ingested.Published evidence is silent on the relationship between fasting times, gastric volume, or gastric acidity and the risk of emesis/reflux or pulmonary aspiration in humans. Studies comparing fasting times of between 2 and 4 hours versus more than 4 hours found smaller gastric volumes in adult patients who fasted 2 to 4 hours, although the effect size was small. No differences in gastric volume were found for children who fasted 2 to 4 hours versus more than four hours. In studies that examine the ingestion of clear liquids between 2 and 4 hours before procedures and in which ingested liquid volumes were recorded, participants received volumes of clear liquids ranging widely from 2 ml/kg to unrestricted amounts. Published evidence is equivocal regarding the effect of clear liquid ingestion on gastric acidity for both adults and children.The Consultants are equivocal regarding a fasting period for clear liquids of between 2 and 4 hours for adults, but they support a fasting period of 2 hours for infants and children. The Task Force supports a fasting period for clear liquids of 2 hours for all patients.Recommendations: It is appropriate to fast from intake of clear liquids for 2 or more hours before procedures requiring general anesthesia, regional anesthesia, or sedation/analgesia (i.e., monitored anesthesia care)Table 1. Examples of clear liquids include, but are not limited to, water, fruit juices without pulp, carbonated beverages, clear tea, and black coffee. These liquids should not include alcohol. The volume of liquid ingested is less important than the type of liquid ingested.There is insufficient published evidence to evaluate the relationship of the timing of breast milk intake before procedures to the incidence of emesis/reflux or pulmonary aspiration. The Consultants and Task Force support a fasting period for breast milk of 4 hours for both neonates and infants.Recommendations: It is appropriate to fast from intake of breast milk for 4 or more hours before procedures requiring general anesthesia, regional anesthesia, or sedation/analgesia (i.e., monitored anesthesia care)Table 1.There is insufficient published evidence to address the safety of any preoperative fasting period for infant formula. For infants and children, the Consultants and Task Force support a fasting period of 6 hours. For neonates, the Consultants support a fasting period of 4 hours, and the Task Force supports a fasting period of 6 hours.Recommendations: It is appropriate to fast from intake of infant formula for 6 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or sedation/analgesia (i.e., monitored anesthesia care)Table 1.There is insufficient published evidence to address the safety of any preoperative fasting period for solids or non-human milk. For patients of all ages, the Consultants and Task Force support a fasting period for a light meal (e.g., toast and a clear liquid) of 6 hours before elective procedures requiring general anesthesia, regional anesthesia, or sedation/analgesia (i.e., monitored anesthesia care). They also support a fasting period for a meal that includes fried or fatty foods or meat of 8 or more hours before elective procedures. For infants and children, the Consultants and Task Force support a fasting period of 6 hours for non-human milk.Recommendations: It is appropriate to fast from intake of a light meal or non-human milk for 6 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or sedation/analgesia (i.e., monitored anesthesia care)Table 1. The Task Force notes that intake of fried or fatty foods or meat may prolong gastric emptying time. Both the amount and type of foods ingested must be considered when determining an appropriate fasting period. Since non-human milk is similar to solids in gastric emptying time, the amount ingested must be considered when determining an appropriate fasting period.Published evidence supports the efficacy of gastrointestinal stimulants (e.g., metoclopramide) for reducing gastric volume during the perioperative period. It is equivocal regarding the relationship between gastrointestinal stimulants and gastric acidity. There is insufficient published evidence to examine the relationship between gastrointestinal stimulants and the frequency of pulmonary aspiration. The Consultants and Task Force are equivocal regarding the preoperative use of gastrointestinal stimulants to reduce the risks of pulmonary aspiration.Recommendations: The routine preoperative use of gastrointestinal stimulants to decrease the risks of pulmonary aspiration in patients who have no apparent increased risk for pulmonary aspiration is not recommended (Table 2).Published evidence supports the efficacy of histamine-2 receptor antagonist agents (e.g., cimetidine, famotidine, or ranitidine) to reduce gastric acidity and volume during the perioperative period and also suggests that proton pump inhibitors (e.g., omeprazole or lansoprazole) are effective for these same purposes. However, it does not sufficiently examine the relationship between reduced gastric acid secretion and the frequency of pulmonary aspiration in humans, and it is silent on the relationship between agents that block gastric acid secretion and the frequency of pulmonary aspiration. There is not sufficient published evidence to evaluate whether reduced gastric acid secretion is associated with decreased morbidity or mortality in patients who have aspirated gastric contents. The Consultants and Task Force are equivocal regarding the use of agents that block preoperative gastric acid secretion to reduce the risks of pulmonary aspiration.Recommendations: The routine preoperative use of medications that block gastric acid secretion to decrease the risks of pulmonary aspiration in patients who have no apparent increased risk for pulmonary aspiration is not recommended.Published evidence supports the efficacy of preoperative antacids (e.g., sodium citrate, sodium bicarbonate, or magnesium trisilicate) for decreasing gastric acidity during the perioperative period, but it does not support their efficacy in reducing gastric volume. It does not sufficiently examine the relationship between reduced gastric acidity and the frequency of pulmonary aspiration in humans. It also does not examine the relationship between the preoperative use of antacids and the frequency of There is insufficient published evidence to evaluate whether reduced gastric acidity or volume is associated with decreased morbidity or mortality in patients who have aspirated gastric contents. The Task Force that the pulmonary aspiration of antacids that with that do may increase the risk of pulmonary The Consultants and Task Force are equivocal regarding the preoperative use of The routine preoperative use of antacids to decrease the risks of pulmonary aspiration in patients who have no apparent increased risk for pulmonary aspiration is not antacids should be used when antacids are for patients for purposes other than reducing the risk of pulmonary evidence suggests that preoperative (e.g., reduce and during the perioperative period, but statistical was not The literature does not sufficiently examine the relationship between or and the frequency of pulmonary aspiration in during the perioperative period, does it sufficiently examine the relationship between preoperative and the frequency of pulmonary aspiration. The Consultants and Task Force are equivocal regarding the preoperative use of These Guidelines do not address the use of during the period upper airway protective reflexes are no The routine preoperative use of to reduce the risks of pulmonary aspiration in patients who have no apparent increased risk for pulmonary aspiration is not recommended.Published evidence is equivocal regarding the use of (e.g., or to decrease gastric volume or acidity. The Consultants and Task Force agree that the preoperative use of is not associated with improved outcomes related to pulmonary aspiration.Recommendations: The use of to decrease the risks of pulmonary aspiration is not recommended.Published evidence supports the preoperative effectiveness of as histamine-2 receptor gastrointestinal and to decrease gastric volume and acidity. However, it is equivocal regarding the of agents when with It also does not sufficiently examine the relationship between reduced gastric volume or acidity and the frequency of pulmonary aspiration in humans, and it is silent on the relationship between pharmacologic agents and the frequency of pulmonary aspiration. There is not sufficient published evidence to evaluate whether reduced gastric volume or acidity is associated with decreased morbidity or mortality in patients who have aspirated gastric contents. The Consultants and Task Force are equivocal regarding the use of pharmacologic agents to reduce the frequency or severity of complications associated with pulmonary aspiration.Recommendations: The routine preoperative use of agents in patients who have no apparent increased risk for pulmonary aspiration is not scientific assessment of these Guidelines was on the following or evidence These directional about between preoperative fasting and pharmacologic of pulmonary aspiration and clinical A preoperative assessment (e.g., history, physical patient patient satisfaction, and of For adults, preoperative fasting of solids between 4 and 8 patient patient satisfaction, and of For adults, preoperative fasting of liquids between 2 and 4 patient patient satisfaction, and of For children, infants and neonates, preoperative fasting of breast milk or formula between 2 and 4 patient patient satisfaction, and of Preoperative gastrointestinal patient patient satisfaction, and of Preoperative pharmacologic of gastric acid secretion (i.e., histamine-2 receptor and proton pump patient patient satisfaction, and of Preoperative increase patient reduce patient satisfaction, and of Preoperative increase patient reduce patient satisfaction, and of Preoperative increase patient reduce patient satisfaction, and of Preoperative agents (e.g., increase patient reduce patient satisfaction, and of evidence was from aggregated research with when and from open and other For purposes of literature relevant clinical studies were and of the The a period from The a period of time from were a of that related to the 10 evidence review of the studies not provide and were A of literature was according to the or of the outcome to the a should either evaluate a or (e.g., for in to evaluate an outcome. 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