Prophylaxis against acid aspiration in regional anesthesia for elective cesarean section: a comparison between oral single-dose ranitidine, famotidine and omeprazole assessed with fiberoptic gastric aspiration. Intravenous administration of the proton pump inhibitor omeprazole reduces the risk of acid aspiration at emergency cesarean section. [Prophylaxis of intraoperative nausea and vomiting with sub-hypnotic dose of propofol during intradural anesthesia in cesarean section]. The antiemetic efficacy and safety of prophylactic metoclopramide for elective cesarean delivery during spinal anesthesia. A comparison of omeprazole and ranitidine for prophylaxis against aspiration pneumonitis in emergency caesarean section. The effect of different pre-operative feeding regimens on plasma glucose and gastric volume and pH in infancy. Reducing the risk of major elective surgery: randomised controlled trial of preoperative optimisation of oxygen delivery. Thoracic epidural anesthesia as an adjunct to general anesthesia for cardiac surgery: effects on ventilation-perfusion relationships. Aspiration pneumonitis prophylaxis in obstetric anaesthesia: comparison of effervescent cimetidine-sodium citrate mixture and sodium citrate.
Acid aspiration syndrome is still an important cause which contributes to maternal mortality in obstetric anesthesia. In this study, we compared famotidine, ranitidine, omeprazole with placebo for prophylaxis against aspiration pneumonitis in elective Cesarean section under regional anesthesia.
                One hundred and sixty patients undergoing elective Cesarean section under spinal anesthesia were allocated randomly into four groups: Group P (n = 40) received placebo only; Group F (n = 40) received famotidine 40 mg Group R (n = 40) received ranitidine 300 mg; and Group O (n = 40) received omeprazole 40 mg. All drugs were given orally at least three hours before the patients entering the operating room. Gastric content was directly aspirated and measured respectively with a flexible fiberoscope under visualization and by a pH meter after delivery.
                Although these three drugs (F, R, and O) were all effective in controlling the secretion of gastric acid, from gastric analysis it was demonstrated that famotidine and ranitidine could be more defective to neutralize acidity than omeprazole (p < 0.05). Percentages of patients with pH < or = 2.5 in Groups P, F, R, and O were respectively 88%, 10%, 8%, and 21%, showing that the innate pH of gastric juice was far lower than expected. Patients receiving omeprazole in single oral dose regimen retained a greater gastric volume (> or = 0.4 ml/kg) than those who received famotidine or ranitidine (p < 0.005). From the criteria defining the patients "at risk" (pH < or = 2.5 and gastric volume > or = 0.4 ml/kg), it is speculated that all these three regimens could potentially reduce the incidence of patients with calculated risk.
                Our data demonstrated that parturients under regional anesthesia were at a higher risk of aspiration pneumonitis than generally thought. Single dose of ranitidine or famotidine administered orally three hours before surgery provided a more effective means to control and neutralize gastric secretion than omeprazole in parturients. This study documented gastric pH and volume, and the number of patients at risk for acid aspiration of gastric contents, in a group of mothers undergoing emergency cesarean section under general anesthesia. Patients were randomized in a double-blind fashion to receive omeprazole 40 mg intravenously or placebo at the time of decision to proceed to cesarean section. In addition, all patients received 10 mg intravenous metoclopramide and 30 mL of 0.3 M sodium citrate. Aspiration of gastric contents was undertaken immediately after endotracheal intubation (PI) and before tracheal extubation (PE). Patients with both pH < 3.5 and volume > 25 mL were deemed to be at risk of acid aspiration should regurgitation occur. Only cases where the study-drug-to-PI-aspiration interval was > 30 min were evaluated. There were 282 patients in the study group and 259 in the control group. PI, 11 patients (4.25%; 95% confidence interval [CI] 1.79-6.71) were at risk in the control group compared with 4 (1.42%; 95% CI 0.04-2.8) in the study group (P = 0.045). The omeprazole-to-PI-aspiration interval in these four cases was < or = 40 min. PE, 19 (7.3%; 95% CI 4.17-10.51) patients were at risk in the control group compared with 2 (0.7%; 95% CI 0-1.69) in the study group (P < 0.0001). Mean pH in patients receiving omeprazole was significantly higher (P < 0.001) than in the control group. Gastric volumes were significantly lower in the omeprazole group compared with the control group at both PI (P = 0.006) and PE (P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS) To determine the preventive and therapeutic effect of 10 mg of propofol administered after delivery on the incidence of intraoperative nausea and vomiting (IONV) during intradural anesthesia for cesarean delivery.
                Controlled, randomized double blind study of 60 women (ASA I-II) receiving intradural anesthesia for elective or deferred emergency cesarean delivery. The propofol group received 10 mg i.v. immediately after fetal extraction. The control group received an equal volume of Intralipid. The presence of IONV after administration of the prophylactic bolus was treated with a second bolus, and if nausea had not subsided completely after two minutes, treatment was topped up with dehydro-benzoperidol.
                The control group included 31 women and the propofol group 29, of whom 3 were excluded. Control variables were similar in the two groups. There were no significant differences in the incidence and severity of IONV between the two groups (22.5 versus 23%). The top-up antiemetic drug was used in the same number of patients in each group.
                Although 10 mg propofol has been described as an effective direct antiemetic, episodes of IONV were neither prevented nor reversed by its use during intradural anesthesia for cesarean delivery. The efficacy and safety of intravenous metoclopramide administered prophylactically before elective cesarean delivery under spinal anesthesia was studied.
                In a double-blind, randomized fashion, 42 ASA Physical Status I-II parturients at term were assigned to receive either 10-mg intravenous metoclopramide or an equal volume of normal saline before induction of spinal anesthesia. The occurrence of nausea and/or vomiting recorded throughout the perioperative period until the patient was admitted to the recovery room. Neonatal acid-base status and neurobehavioral exams were obtained.
                Patients in the group receiving metoclopramide had a significantly lower incidence of nausea and vomiting both before and after delivery than the control group (14% versus 81% overall). All neonatal acid-base values were within normal limits and there were no significant differences in neurobehavioral exam results between the two groups.
                Metoclopramide administered before induction of spinal anesthesia for cesarean delivery appears to significantly reduce both pre- and postdelivery emetic symptoms without apparent adverse effects on mother or neonate. One hundred and sixty-two Chinese women undergoing emergency Caesarean section were allocated at random on admission to the labour ward to receive one of three regimens for orally administered chemoprophylaxis against acid aspiration: ranitidine 150 mg 6 hourly with sodium citrate at induction of anaesthesia, omeprazole 40 mg 12 hourly with sodium citrate, or omeprazole 40 mg 12 hourly alone. Intragastric pH and volume were measured immediately after induction of anaesthesia. Ten patients (17%) in the omeprazole-only group, three (6%) in the omeprazole and citrate group and one (2%) in the ranitidine group had an intragastric pH less than 2.5 and volume greater than 25 ml (p less than 0.05). The use of sodium citrate resulted in higher intragastric pH but larger intragastric volumes (p less than 0.05). The sodium citrate and ranitidine regimen was the most cost-effective among the three. The effects of four different pre-operative feeding regimens were studied in 123 children below the age of one year presenting for surgery. Plasma glucose concentrations, blood acid-base values, gastric volume and gastric pH were measured before and after induction of anaesthesia. No patient was found to be hypoglycaemic and there were no significant differences in plasma glucose concentration and acid-base values between the groups. No correlation was demonstrated between the age and weight of the patients and the duration of fasting and the plasma glucose concentration. There was a significant elevation of plasma glucose concentration in all four groups after induction of anaesthesia (P less than 0.001) compared with the pre-induction level which is a reflection of the stress of blood sampling and induction of anaesthesia. Infants less than three months of age in the milk-feed group had a significantly higher gastric volume with low pH (P less than 0.05) signifying a potentially greater risk of pulmonary acid aspiration. The practice of timing the last pre-operative feed in infancy according to the infant's normal feeding pattern does not appear to increase the risk factors for pulmonary aspiration, if milk is avoided. To determine whether preoperative optimisation of oxygen delivery improves outcome after major elective surgery, and to determine whether the inotropes, adrenaline and dopexamine, used to enhance oxygen delivery influence outcome.
                Randomised controlled trial with double blinding between inotrope groups. Setting: York District Hospital, England.
                138 patients undergoing major elective surgery who were at risk of developing postoperative complications either because of the surgery or the presence of coexistent medical conditions. Interventions: Patients were randomised into three groups. Two groups received invasive haemodynamic monitoring, fluid, and either adrenaline or dopexamine to increase oxygen delivery. Inotropic support was continued during surgery and for at least 12 hours afterwards. The third group (control) received routine perioperative care.
                Hospital mortality and morbidity.
                Overall, 3/92 (3%) preoptimised patients died compared with 8/46 controls (17%) (P=0.007). There were no differences in mortality between the treatment groups, but 14/46 (30%) patients in the dopexamine group developed complications compared with 24/46 (52%) patients in the adrenaline group (difference 22%, 95% confidence interval 2% to 41%) and 28 patients (61%) in the control group (31%, 11% to 50%). The use of dopexamine was associated with a decreased length of stay in hospital.
                Routine preoperative optimisation of patients undergoing major elective surgery would be a significant and cost effective improvement in perioperative care. To determine the effects of thoracic epidural anesthesia (TEA) on ventilation-perfusion (VA/Q) relationships, atelectasis, and oxygenation before and after coronary artery bypass graft surgery (CABG).
                Prospective, controlled, unblinded, randomized trial.
                Cardiothoracic clinic at a major university referral center.
                Twenty-eight patients undergoing elective CABG.
                Perioperative and postoperative TEA was added to general anesthesia (GA) in 14 patients, and 14 patients receiving GA alone served as controls.
                VA/Q relationships were measured by the multiple inert gas elimination technique, and, 20 hours postoperatively, atelectasis was assessed by computerized tomographic scans. Arterial and mixed venous blood gases and hemodynamic variables were measured by standard techniques. TEA per se caused no change in shunt, VA/Q matching, or oxygenation. Induction of GA in the control group and induction of TEA caused similar reductions in mean arterial pressure. The TEA patients needed less morphine analgesia postoperatively and were extubated earlier. Extubation caused significant improvement in VA/Q matching. On the first postoperative day, a slight reduction in PaCO2 was seen in the TEA group, but no differences in shunt, VA/Q matching, or oxygenation compared with the GA group. Both groups showed extensive bilateral atelectasis.
                TEA can reduce respirator time and the need for morphine analgesics after CABG without negative effects on VA/Q matching, oxygenation, or atelectasis formation. One hundred and forty-seven patients undergoing elective or emergency Caesarean section under general anaesthesia were allocated randomly to three groups: group 1 (n = 28) received no premedication; group 2 (n = 58) received 0.3-molar sodium citrate 15 ml (sodium citrate 1.16 g); group 3 (n = 61) received effervescent cimetidine-sodium citrate combination (cimetidine 400 mg with sodium citrate 0.9 g) after entering the operating room. Gastric pH was measured at tracheal intubation (pH1) and extubation (pH2). Mean pH1 and mean pH2 values in group 1 were, respectively, 2.25 (SD 1.35) and 2.83 (1.64). Mean pH1 and pH2 values in group 2 were, respectively, 4.38 (1.44) and 4.57 (1.51). In group 3 mean pH1 and pH2 values were, respectively, 5.07 (1.13) and 5.37 (1.30). Percentages of patients with pH1 less than or equal to 2.5 in groups 1, 2 and 3 were, respectively, 75, 13.8 and 1.6. Percentages of patients with pH2 less than or equal to 2.5 in groups 1, 2 and 3 were 50, 10.3 and 1.6, respectively.
There is no good evidence to support the routine administration of acid prophylaxis drugs in normal labour to prevent gastric aspiration and its consequences. Giving such drugs to women once a decision to give general anaesthesia is made, is assessed in another Cochrane review.
[Note: The four citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]