Preoperative fasting

An international multidisciplinary consensus statement on fasting before procedural sedation in adults and children

The multidisciplinary International Committee for the Advancement of Procedural Sedation presents the first fasting and aspiration prevention recommendations specific to procedural sedation, based on an extensive review of the literature. These were developed using Delphi methodology and assessment of the robustness of the available evidence. The literature evidence is clear that fasting, as currently practiced, often substantially exceeds recommended time thresholds and has known adverse consequences, for example, irritability, dehydration and hypoglycaemia. Fasting does not guarantee an empty stomach, and there is no observed association between aspiration and compliance with common fasting guidelines. The probability of clinically important aspiration during procedural sedation is negligible. In the post-1984 literature there are no published reports of aspiration-associated mortality in children, no reports of death in healthy adults (ASA physical status 1 or 2) and just nine reported deaths in adults of ASA physical status 3 or above. Current concerns about aspiration are out of proportion to the actual risk. Given the lower observed frequency of aspiration and mortality than during general anaesthesia, and the theoretical basis for assuming a lesser risk, fasting strategies in procedural sedation can reasonably be less restrictive. We present a consensus-derived algorithm in which each patient is first risk-stratified during their pre-sedation assessment, using evidence-based factors relating to patient characteristics, comorbidities, the nature of the procedure and the nature of the anticipated sedation technique. Graded fasting precautions for liquids and solids are then recommended for elective procedures based upon this categorisation of negligible, mild or moderate aspiration risk. This consensus statement can serve as a resource to practitioners and policymakers who perform and oversee procedural sedation in patients of all ages, worldwide.

The impact and safety of preoperative oral or intravenous carbohydrate administration versus fasting in colorectal surgery--a randomized controlled trial

BACKGROUND AND AIMS

Increasing evidence suggests that preoperative fasting, as was the clinical practice for many decades, might be associated with untoward consequences and that a standardized preoperative intake of nutrients might be advantageous; this is a component of the enhanced recovery after surgery (ERAS) concept. Thus, in a randomized controlled trial we compared preoperative fasting with preoperative preparation with either oral or intravenous intake of carbohydrates, minerals and water. Biochemical, psychosomatic, echocardiographic and muscle-power parameters were assessed in surgical patients with colorectal diseases during the short-term perioperative period. We also assessed the safety of peroral intake shortly before surgery.

METHODS

A total of 221 elective colorectal surgery patients in this bicentric, randomized, prospective and blinded clinical trial were divided into three groups: A - patients fasting from midnight (control group); B - patients supported preoperatively by glucose, magnesium and potassium administered intravenously; C - patients supported preoperatively by oral consumption of a specifically composed solution (potion).

RESULTS

The general perioperative clinical status of patients in groups C and B was significantly better than those in group A. Psychosomatic conditions postoperatively were found to be best in group C (P < 0.029). The rise in the index of insulin resistance (QUICKI) from the preoperative to the postoperative state was significant in group A (P < 0.05). The systolic and diastolic function of the left ventricle improved postoperatively in group C vs. group A (P < 0.04), and the ejection fraction was also significantly higher postoperatively in group C vs. group A (P < 0.03). The gastric residual volume was 5 ml and the pH of stomach juice was 3.5-5 in all groups without statistically significant difference. No difference was found in the length of hospital stay or the rate of complications.

CONCLUSIONS

Preoperative fasting does not confer any benefit or advantage for surgical patients. In contrast, consumption of an appropriate potion composed of water, minerals and carbohydrates offers some protection against surgical trauma in terms of metabolic status, cardiac function and psychosomatic status. Peroral intake shortly before surgery did not increase gastric residual volume and was not associated with any risk.

Fasting and Emergency Department Procedural Sedation and Analgesia: A Consensus-Based Clinical Practice Advisory

Emergency physicians frequently administer procedural sedation and analgesia to nonfasted patients; however, they currently have no specific guidelines to aid them in preprocedural risk stratification. We assembled a committee of leading emergency physician sedation researchers to develop a consensus-based clinical practice advisory for this purpose. Our goal was to create a tool to permit emergency physicians to identify prudent limits of sedation depth and timing in light of fasting status and individual patient risk factors. The advisory is not intended to assert a legal standard of practice or absolute requirement. It is expected that emergency physicians will at times appropriately deviate from it according to individualized judgment and unique clinical circumstances.

Preoperative fasting

BACKGROUND AND METHODS

To avoid pulmonary aspiration, fasting after midnight has become standard in elective surgery, but recent studies have found no scientific support for this practice. Several anaesthesia societies now recommend a 2-h preoperative fast for clear fluids and a 6-h fast for solids in most elective patients. The literature supporting such fasting recommendations was reviewed.

RESULTS

The recommendations are safe and improve well-being before operation, mainly by reducing thirst. A carbohydrate-rich beverage given before anaesthesia and surgery alters metabolism from the overnight fasted to the fed state. This reduces the catabolic response (insulin resistance) after operation, which may have implications for postoperative recovery.

CONCLUSION

Most patients having elective operations can be allowed a free intake of clear fluids up to 2 h before anaesthesia. Preoperative carbohydrates reduce postoperative insulin resistance.

Preoperative fasting: old habits die hard

OVERVIEW

Prolonged preoperative fasting is a time-honored tradition. The typical order of "npo after midnight" (or no liquid or food after 12 am on the day of surgery) has been challenged in recent years-so much so that in 1999 the American Society of Anesthesiology (ASA) revised its practice guidelines for preoperative fasting in healthy patients undergoing elective procedures. The newer, more liberal recommendations, based on studies showing that pulmonary aspiration occurs only rarely as a complication of modern anesthesia, allow the consumption of clear liquids up to two hours before elective surgery, a light breakfast (tea and toast, for example) six hours before the procedure, and a heavier meal eight hours beforehand. There is a well-known lag between the dissemination and implementation of practice guidelines, so the authors sought to determine whether the publication of the revised ASA recommendations had changed preoperative fasting practices. They interviewed 155 patients in one hospital about their preoperative fasting, comparing instructed, actual, and ASA-recommended fasting durations for liquids and solids. Their findings demonstrate that the majority of patients continued to receive instructions of npo after midnight for both liquids and solids, whether they were scheduled for early or late surgery. On average, the patients fasted from liquids and solids for 12 and 14 hours, respectively, with some patients fasting as long as 20 hours from liquids and 37 hours from solids. These fasts were significantly longer than those recommended by the ASA, indicating that inappropriate preoperative fasting is an issue that demands attention. The authors conclude that more collaboration between nurses and physicians is needed to assure that fasting instructions are consistent with the ASA guidelines and that patients understand these directives.

Pulmonary aspiration risk during emergency department procedural sedation--an examination of the role of fasting and sedation depth

The assessment of pre-procedure fasting and control of sedation depth are prominent elements of widely disseminated procedural sedation guidelines and of the Joint Commission on Accreditation of Healthcare Organizations' standards. Both exist primarily to minimize the risk of pulmonary aspiration of gastric contents. This paper critically examines the literature on pre-procedure fasting and controlling sedation depth in association with pulmonary aspiration, and interprets this evidence in the context of modern emergency medicine practice. The article reviews the pathophysiology of aspiration and changing concepts regarding aspiration risk over the last decade. After reviewing studies on aspiration risk during general anesthesia, the paper reviews the risk of aspiration during labor and delivery as a more appropriate comparison group for aspiration risk during emergency department procedural sedation and analgesia (ED PSA). It is noted that aspiration during ED PSA has not been reported in the medical literature and that aspiration during general anesthesia and labor and delivery is uncommon. The literature provides no compelling evidence to support specific fasting periods for either liquids or solids prior to PSA, and existing guidelines for elective patients are of necessity arbitrary and based upon consensus opinion. The article discusses the implications in the areas of training and preparedness, monitoring, and research for the emergency physician practicing PSA.