This guideline aims to provide an overview of the present knowledge on aspects of perioperative fasting with assessment of the quality of the evidence. A systematic search was conducted in electronic databases to identify trials published between 1950 and late 2009 concerned with preoperative fasting, early resumption of oral intake and the effects of oral carbohydrate mixtures on gastric emptying and postoperative recovery. One study on preoperative fasting which had not been included in previous reviews and a further 13 studies published since the most recent review were identified. The searches also identified 20 potentially relevant studies of oral carbohydrates and 53 on early resumption of oral intake. Publications were classified in terms of their evidence level, scientific validity and clinical relevance. The Scottish Intercollegiate Guidelines Network scoring system for assessing level of evidence and grade of recommendations was used. The key recommendations are that adults and children should be encouraged to drink clear fluids up to 2 h before elective surgery (including caesarean section) and all but one member of the guidelines group consider that tea or coffee with milk added (up to about one fifth of the total volume) are still clear fluids. Solid food should be prohibited for 6 h before elective surgery in adults and children, although patients should not have their operation cancelled or delayed just because they are chewing gum, sucking a boiled sweet or smoking immediately prior to induction of anaesthesia. These recommendations also apply to patients with obesity, gastro-oesophageal reflux and diabetes and pregnant women not in labour. There is insufficient evidence to recommend the routine use of antacids, metoclopramide or H2-receptor antagonists before elective surgery in non-obstetric patients, but an H2-receptor antagonist should be given before elective caesarean section, with an intravenous H2-receptor antagonist given prior to emergency caesarean section, supplemented with 30 ml of 0.3 mol l(-1) sodium citrate if general anaesthesia is planned. Infants should be fed before elective surgery. Breast milk is safe up to 4 h and other milks up to 6 h. Thereafter, clear fluids should be given as in adults. The guidelines also consider the safety and possible benefits of preoperative carbohydrates and offer advice on the postoperative resumption of oral intake.

We conducted a randomized, double-blind comparison of 8% sevoflurane and propofol as induction agents for day-case cystoscopy in 102 patients. All patients received an i.v. cannula and breathed oxygen 5 litre min-1. Anaesthesia was induced with propofol i.v. or inhalation of 8% sevoflurane and 10% Intralipid (as a placebo) i.v., delivered by a blinded observer. Anaesthesia was maintained in all patients with 2% sevoflurane via a face mask. Induction of anaesthesia with sevoflurane was significantly slower compared with propofol (mean 84 (SD 24) s vs 57 (11) s), but was associated with a lower incidence of apnoea (16% vs 65%) and a shorter time to establish spontaneous ventilation (94 (34) s vs 126 (79) s). Induction complications were uncommon in each group but the transition to maintenance was smoother with sevoflurane and was associated with less hypotension compared with propofol. Emergence from anaesthesia induced with sevoflurane occurred significantly earlier compared with propofol (5.2 (2.2) min vs 7.0 (3.2) min) and anaesthetic induction was also significantly cheaper with sevoflurane. According to a postoperative questionnaire, the majority of patients found both anaesthetic techniques acceptable. Nevertheless, significnatly more patients (14%) rated induction with sevoflurane as unpleasant compared with propofol (0) and significantly more patients (24%) would not choose sevoflurane induction compared with propofol (6%). This phenomenon may have been related to the particular patient population studied, however. Inhalation induction with 8% sevoflurane would appear to offer several objective advantages compared with induction with propofol in day-case patients, although a significant minority may dislike this technique.

History of sevoflurane Research to develop a safe, non-inflammable inhaled anaesthetic agent began in the 1930s when chemists discovered that the substitution of fluorine for other halogens "lowers the boiling point, increases stability, and generally decreases toxicity" [5]. This work was continued by McBee, who used his knowledge of fluorine chemistry gained from working on the "Manhattan" atomic bomb project, to investigate a number of fluorine-containing compounds, none of which was eventually suitable for clinical use. In 1951, Suckling synthesized halothane, and soon the search for other clinically useful fluorine-containing anaesthetics began in earnest.

Use of remifentanil alone for MAC did not provide optimal sedation during local anesthesia. However, 0.05 to 0.1 microgram.kg-1.min-1 remifentanil in combination with 2 mg midazolam given intravenously, provided effective sedation and analgesia during MAC in healthy patients classified as American Society of Anesthesiologists status 1 to 2. Midazolam also produced dose-dependent potentiation of remifentanil's depressant effect on respiratory rate. In outpatients receiving a combination of midazolam and remifentanil during local anesthesia, the level of sedation appears to influence the incidence of both intraoperative pruritus and PONV.

Induction of, maintenance of, and recovery from sevoflurane anesthesia were compared with propofol and isoflurane anesthesia when administered with nitrous oxide to patients undergoing gynecologic surgery. Seventy-five healthy (ASA I or II), consenting patients were randomly assigned to receive either (I) propofol for induction of anesthesia and isoflurane-nitrous oxide for maintenance (control), (II) propofol for induction and sevoflurane-nitrous oxide for maintenance, or (III) sevoflurane-nitrous oxide for induction and maintenance of anesthesia. Inhaled induction of anesthesia with sevoflurane-nitrous oxide was rapid (109 +/- 25 s to loss of consciousness) and without any untoward hemodynamic changes or episodes of coughing and laryngospasm. Mean arterial blood pressure after induction of anesthesia with propofol (71 +/- 11, 73 +/- 12 mm Hg for groups I and II, respectively) was lower than when sevoflurane (80 +/- 14 mm Hg) was used. The emergence time after discontinuation of isoflurane-nitrous oxide (6.7 +/- 2.2 min) was significantly longer than after propofol-sevoflurane-nitrous oxide or sevoflurane-nitrous oxide alone (4.1 +/- 2.2 and 4.0 +/- 2.0 min for groups II and III, respectively). However, later recovery events did not differ between groups. Serum fluoride levels increased after administration of sevoflurane but not isoflurane. The levels of fluoride ions correlated with the degree of exposure to sevoflurane in MAC-hours. In conclusion, induction of anesthesia with either propofol or sevoflurane-nitrous oxide was rapid and without significant side effects. Emergence and early recovery after maintenance of anesthesia with sevoflurane-nitrous oxide was significantly faster than that after an isoflurane-nitrous oxide combination.

Three different anesthetic techniques were compared in 146 healthy outpatients undergoing ambulatory surgery. In Groups I and II, anesthesia was induced with propofol (1.5-2.0 mg/kg, intravenously [iv]) and maintained with nitrous oxide (N2O) 60% in oxygen and either a propofol infusion, 75-160 micrograms.kg-1.min-1 IV, or sevoflurane, 1%-2% end-tidal, respectively. In Group III, anesthesia was induced and maintained with sevoflurane, 1%-4% end-tidal and N2O 60% in oxygen. In addition to 60% N2O in oxygen at a total gas flow of 3 L/min, all patients received fentanyl, 2-3 micrograms/kg IV, and vecuronium, 0.1 mg/kg IV. IV induction of anesthesia with propofol (90 +/- 53 s and 94 +/- 48 s in Groups I and II, respectively) was significantly faster than inhalation induction with sevoflurane (153 +/- 100 s). There were no significant differences in the incidence of coughing, airway irritation, or laryngospasm during induction of anesthesia. Although the mean arterial blood pressure values were similar in all three groups, the use of sevoflurane was associated with consistently lower heart rate values during the early maintenance period. Early and intermediate recovery times were the same in all three treatment groups. The use of sevoflurane for induction and/or maintenance of anesthesia was associated with a higher incidence of postoperative emetic sequelae compared with propofol. Finally, the times at which patients were considered "fit for discharge" and the actual discharge times were similar in all three groups. Sevoflurane is an acceptable alternative to propofol for induction and maintenance of outpatient anesthesia.

Day-case anaesthesia requires rapidly eliminated anaesthetics which are relatively expensive. This multinational, multicentre European study assessed the relative costs of propofol or sevoflurane anaesthesia in 211 patients. Anaesthesia was induced and maintained with propofol in group 1, with propofol and sevoflurane in group 2, and with sevoflurane in group 3. Drug and delivery costs were calculated in US$. Induction of anaesthesia was fastest in groups 1 and 2, although spontaneous ventilation resumed earliest in group 3. Emergence times and times at which patients were fit for discharge were similar in all groups. Group 2 had the lowest costs based on actual drug use (mean $14.2 (SEM 0.8) vs $18.7 (0.8) and $17.3 (0.8) in groups 1 and 3, respectively). Anaesthetic drug wastage and disposable costs were highest in group 1 and lowest in group 3. Consequently, total costs were highest in group 1 ($31.9 (0.9)) compared with groups 2 ($19.7 (0.9)) and 3 ($18.8 (0.9)). Although we observed increased nausea and vomiting in groups 2 and 3 and reduced patient satisfaction in group 3, these differences should be balanced against the greater cost of propofol anaesthesia.

SummaryWe compared target-controlled propofol with sevoflurane in a randomised, double-blind study in 61 day-case patients. Anaesthesia was induced with a propofol target of 8 mg.ml ¹1 or 8% sevoflurane, reduced to 4 mg.ml ¹1 and 3%, respectively, after laryngeal mask insertion and subsequently titrated to clinical signs. Mean (SD) times to unconsciousness and laryngeal mask insertion were significantly shorter with propofol [50 (9) s and 116 (33) s, respectively] than with sevoflurane [73 (14) s and 146 (29) s; p < 0.0001 and p ¼ 0.0003, respectively]; however, these differences were not apparent to the blinded observer. Propofol was associated with a higher incidence of intra-operative movement (55 vs. 10%; p ¼ 0.0003), necessitating more adjustments to the delivered anaesthetic. Emergence was faster after sevoflurane [5.3 (2.2) min vs. 7.1 (3.7) min; p ¼ 0.027], but the inhaled anaesthetic was associated with more nausea and vomiting (30 vs. 3%; p ¼ 0.006), which delayed discharge [258 (102) min vs. 193 (68) min; p ¼ 0.005]. Direct costs were lower with sevoflurane but nausea would have increased indirect costs. Patient satisfaction was high (Ն 90%) with both techniques. In conclusion, both techniques had advantages and disadvantages for day-case anaesthesia.