Best practice & research. Clinical anaesthesiology
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The gastric emptying rate is a carefully regulated process consisting of different mathematically defined phases. The gastric metabolic load, as well as neural regulatory mechanisms and hormonal influences, cooperate in order to achieve a well-balanced emptying of contents from the stomach into the duodenum for absorption in the small intestine. ⋯ We have found that the two peptide hormones ghrelin and glucagon-like peptide- I (GLP- I) have a great impact on the regulation of gastric emptying: ghrelin is a most potent stimulator of gastric contractions and emptying, and GLP- I profoundly inhibits this emptying process. These data suggest possibilities for governing the rate of gastric emptying as a natural step in achieving metabolic balance and control.
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This review discusses the metabolic changes that occur during fasting, especially in relation to surgical stress. Currently available evidence on the relevance of different aspects of perioperative nutritional support are presented. ⋯ Avoiding preoperative fasting has been shown to be related to a substantial reduction in postoperative stress and insulin resistance. Implementation of a standardized programme with a multimodal approach using evidence-based perioperative routines has been shown to further reduce surgical stress and to markedly enhance functional recovery also after major surgical procedures.
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Best Pract Res Clin Anaesthesiol · Sep 2006
ReviewHow perioperative fluid balance influences postoperative outcomes.
Fasting, anaesthesia and surgery affect the body's physiological capacity not only to control its external fluid and electrolyte balance but also the internal balance between the various body fluid compartments. Conversely, abnormalities of fluid and electrolyte balance may adversely affect organ function and surgical outcome. Perioperative fluid therapy has a direct bearing on outcome, and prescriptions should be tailored to the needs of the patient. ⋯ Weight gain in elective surgical patients should be minimized in an attempt to achieve a 'zero fluid balance status'. On the other hand, these patients should arrive in the anaesthetic room in a state of normal fluid and electrolyte balance so as to avoid the need to resuscitate fluid-depleted patients in the anaesthetic room or after the induction of anaesthesia. Optimal fluid delivery should be part of an overall care package that involves minimization of the period of preoperative fasting, preoperative carbohydrate loading, thoracic epidural analgesia, avoidance of nasogastric tubes, early mobilization, and early return to oral feeding, as exemplified by the enhanced recovery after surgery programme.
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Best Pract Res Clin Anaesthesiol · Sep 2006
Review Historical ArticleFasting from midnight--the history behind the dogma.
The purpose of this chapter is to review historical fasting guidelines and how the dogma of fasting from midnight arose and came to be challenged by randomized clinical trials of preoperative clear liquids versus overnight fast. Medical and anaesthesia textbooks and journals from the 19th and 20th centuries were consulted, and the results of clinical trials and the reaction to them are reviewed. The dogma appeared to result from extrapolation of pulmonary aspiration risk in 'full-stomach' emergency cases to healthy elective cases. ⋯ Subsequent large-scale studies showed the risk to be minimal. Meta-analysis of randomized clinical trials demonstrated the safety of clear oral liquids until 2 hr preoperatively in healthy patients undergoing elective surgery. Reaction was cautious but led to eventual acceptance of evidence-based fasting guidelines.