Prophylaxis for Mendelson's syndrome before elective caesarean section. A comparison of cimetidine and magnesium trisilicate mixture regimens. Comparison of sodium citrate with magnesium trisilicate as pre-anaesthetic antacid in emergency caesarean sections. Analgesic and antacid properties of i.m. tramadol given before Caesarean section under general anaesthesia. Comparison of the prophylactic use of magnesium trisilicate mixture B.P.C., sodium citrate mixture or cimetidine in obstetrics. Intravenous ranitidine reduces the risk of acid aspiration of gastric contents at emergency cesarean section. Effects of omeprazole, with and without metoclopramide, in elective obstetric anaesthesia. [Oral administration of sodium citrate before general anesthesia in elective cesarean section. Effect on pH and gastric volume]. Sodium citrate pretreatment in elective cesarean section patients. Aspiration pneumonitis prophylaxis in obstetric anaesthesia: comparison of effervescent cimetidine-sodium citrate mixture and sodium citrate. A comparison of intravenous ranitidine and omeprazole on gastric volume and pH in women undergoing emergency caesarean section. Cimetidine premedication in elective caesarean section. Intravenous administration of the proton pump inhibitor omeprazole reduces the risk of acid aspiration at emergency cesarean section. [Effectiveness of cimetidine in the prevention of aspiration pneumonia in obstetrics]. A comparison of the effects of omeprazole and ranitidine on gastric secretion in women undergoing elective caesarean section. A comparison of omeprazole and ranitidine for prophylaxis against aspiration pneumonitis in emergency caesarean section. 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.
A clinical trial was conducted in which patients undergoing elective Caesarean section received eitherrr oral cimetidine 400 mg or magnesium trisilicate mixture BPC 20 ml before anaesthesia. The pH values of gastric fluid were significantly higher and the incidence of pH less than 2.5 was significantly lower in patients who received magnesium trisilicate mixture BPC. No adverse effects were observed in newborn infants whose mothers had received cimetidine and there was no significant difference in pH values of gastric fluid from the newborn in the two groups. The findings suggest that as a means of prophylaxis for Mendelson's syndrome in patients undergoing elective Caesarean section, magnesium trisilicate mixture BPC 20 ml is more effective than a single oral dose of cimetidine 400 mg, administered in the manner described. nan Intramuscular (i.m.) tramadol increases gastric pH during anaesthesia similar to famotidine. We investigated the antacid analgesic value of a single dose of i.m. tramadol given 1 h before elective Caesarean section performed under general anaesthesia.
                Sixty ASA I parturients undergoing elective Caesarean section were included in a randomized double-blind study. The patients were randomly allocated to receive i.m. tramadol 100 mg (n=30) or famotidine 20 mg (n=30) 1 h before general anaesthesia.
                At the beginning and the end of anaesthesia, patients receiving tramadol had a median gastric fluid pH of 6.4, which was not significantly different from those treated with famotidine (median 6.3). The infant well-being, as judged by Apgar score, cord blood gas analysis, and neurobehavioural assessment showed no significant difference between the two groups. Nalbuphine consumption in the first 24 h after operation was reduced by 35% in the tramadol group. Pain intensity score on sitting and sedation were significantly greater in famotidine group up to 24 h after surgery. There was no significant difference in incidence and severity of nausea and vomiting between the two groups.
                A single i.m. dose of tramadol is useful pre-treatment to minimize the risk of acid aspiration during operation, and in improving pain relief during 24 h after surgery. The effects of magnesium trisilicate mixture B.P.C., sodium citrate mixture or cimetidine on gastric pH and aspirated gastric volumes were compared in 78 obstetric patients during elective (a), or emergency (b) surgery. Magnesium trisilicate mixture B.P.C. was associated with the most alkaline values of gastric pH (mean (a) 7.9, (b) 7.3; range 2.9-9.1). Sodium citrate 0.3 mol litre-1 mixture resulted in the narrowest range of pH values of gastric contents (mean (a) 5.4, (b) 5.9; range 3.9-7.7). The ranges of aspirated gastric volumes were wide with both antacid regimens (magnesium trisilicate 12-172 ml, sodium citrate 9-290 ml). Cimetidine increased gastric pH to greater than 2.5 in 82% of patients (mean (a) 6.2, (b) 5.0; range 1.6-7.3), and was associated with significantly smaller volumes of aspirated gastric contents (range 0.5-44 ml). When gastric pH and volume were considered together, the groups of patients who received cimetidine were found to be closest to the defined "safe limits", of pH greater than 2.5 and volume less than 25 ml. This study documented gastric pH and volume and the number of patients at risk of 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 ranitidine, 50 mg intravenously, or placebo at the time of decision to proceed to cesarean section. In addition, all patients received 30 mL of 0.3 M sodium citrate on entry into the operating room. Aspiration of gastric contents was undertaken immediately after endotracheal intubation (PI) and before tracheal extubation. Patients with both pH < 3.5 and volume > 25 mL were deemed to be at risk of acid aspiration should regurgitation occur. Postintubation, 12 patients (4%) were at risk in the citrate-alone group and 7 patients (2.3%) were at risk in the ranitidine/citrate group (not significant). Preextubation, 17 patients (5.6%) were at risk in the citrate-alone group and 1 patient (0.3%) was at risk in the ranitidine/citrate group (P < 0.05). PI pH in patients receiving ranitidine/citrate (mean 5.2, SD 0.8) was significantly higher than in patients receiving citrate alone (mean 4.9, SD 1.1). None of the patients who received ranitidine more than 30 min before the PI sample were at risk compared to 6 (3.2%) in the citrate alone group (P = 0.05). We conclude that 50 mg of intravenous ranitidine given at the time of decision to proceed to cesarean section reduces the risk of acid aspiration provided that at least 30 min have elapsed from injection to induction of anesthesia. We report the results of a study comparing two dose regimens of the gastric antisecretory agent, omeprazole, used as prophylaxis against pulmonary aspiration of gastric contents during general anaesthesia for elective Caesarean section. Since antisecretory agents do not clear stomach contents already present at the start of treatment, two groups of patients who had received both omeprazole and a prokinetic drug, metoclopramide, were also studied. Thirty patients received oral omeprazole 40 mg on the evening before and on the morning of the operation (group 1), 33 received oral omeprazole 80 mg on the morning of the operation (group 2), and 15 (group 3) and 16 (group 4) patients respectively received the oral omeprazole doses stated above and in addition metoclopramide 10 mg given intramuscularly at least 20 min before induction of anaesthesia. Gastric aspirate pH and volume were measured at induction of anaesthesia and on completion of surgery. At induction of anaesthesia, treatment was judged successful (pH > or = 2.5 and volume < 25 ml) in 87%, 73%, 100% and 81% of patients in groups 1-4 respectively. The corresponding results on completion of surgery were 100%, 88%, 100% and 100%. While omeprazole is useful as prophylaxis against pulmonary aspiration during general anaesthesia for elective Caesarean section, the addition of a prokinetic agent seems to be necessary to maximise its effects. A study was carried out to assess the effects of oral sodium citrate on the pH and volume of gastric content in 52 unpremedicated women undergoing elective Caesarean section under general anaesthesia. The patients were randomly assigned to two groups: group T (n = 26) without antacids and group C (n = 26) receiving orally 30 ml of 0.3 M sodium citrate solution 5 min before induction of anaesthesia. After tracheal intubation, a size 18 double lumen naso-gastric tube was introduced. The gastric content was sampled 10 min (n = 52), 50 min (n = 52) and 80 min (n = 24) later. Before extubation, the stomach was completely emptied and the naso-gastric tube removed. On each sampling time, the pH was measured with a digital pHmeter; a search for biliary salts (pyloric reflux) was carried out with thin layer chromatography; the volume of the gastric content was measured using the phenol red dilution method. At 10 min, none patient in group C had a gastric pH less than 2.5, in the opposite to 92% of patients in the control group T. The alkalinizing effect of the citrate lasted throughout the evaluation time. The mean pH was respectively 5.3 +/- 1.07, 5.23 +/- 1.2 and 5.53 +/- 1.3 at 10, 50 and 80 min in group C (controls: 1.9 +/- 0.7; 2.49 +/- 1.3; 2.40 +/- 0.61). However, the citrate solution increased significantly the volume of the gastric content. It was respectively 51.1 +/- 29.9 ml, 79.15 +/- 70.9 ml and 32.9 +/- 22.1 ml; 29.6 +/- 28.5 ml; 26.6 +/- 10.9 ml).(ABSTRACT TRUNCATED AT 250 WORDS) Thirty-two healthy term parturients undergoing elective cesarean section randomly received either no antacid (n = 10), 30 ml of 0.3 molar sodium citrate less than 60 min preoperatively (n = 11), or 30 ml of 0.3 molar sodium citrate longer than 60 min preoperatively (n = 11). Immediately after delivery, the stomach was emptied as completely as possible through a #18 Salem Sump tube passed orally. Mean gastric pH in the three groups was 1.8 +/- 2.7 (SD), 5.0 +/- 1.5, and 2.7 +/- 1.2, respectively. Gastric pH was significantly higher in the short interval group than in either the control group or in patients receiving their sodium citrate more than 60 min in advance. Gastric volumes were similar. All control patients had a gastric pH less than 2.5. Nine percent of patients receiving sodium citrate less than 60 min in advance and 50% of patients receiving their sodium citrate longer than 60 min in advance had a pH of less than 2.5. Volumes exceeding 25 ml occurred with equal frequency. No patient in the short interval group had a combination of both pH of less than 2.5 and a volume exceeding 25 ml. This combination occurred with equal frequency in control patients (64%) and in those patients receiving their sodium citrate more than 60 min in advance (50%). We conclude that sodium citrate effectively increases gastric pH when given less than 60 min prior to the induction of anesthesia. 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. We have compared the effect of intravenously administered omeprazole and ranitidine on gastric contents in a double-blind study in 80 consecutive women undergoing emergency Caesarean section. When the decision to perform emergency Caesarean section was made, patients were randomly assigned to receive either ranitidine 50 mg or omeprazole 40 mg intravenously. The volume and pH of the gastric contents were measured immediately after tracheal intubation and again before extubation. The gastric pH was found to be higher after omeprazole than after ranitidine immediately after intubation (5.89 +/- 1.46 and 5.21 +/- 1.36 respectively) (P < 0.05) and before extubation (5.97 +/- 1.38 and 5.32 +/- 1.24 respectively) (P < 0.05). However, the gastric volumes were comparable in both the groups. The number of patients with gastric volume > 25 ml and pH < 2.5 were 3 (7.5%) in the ranitidine group and 1 (2.5%) in the omeprazole group after intubation and none in either of the groups before extubation. We conclude that omeprazole 40 mg iv administered at the time of the decision to operate, results in higher gastric pH than ranitidine in obstetric patients undergoing emergency Caesarean section. A single intramuscular injection of Cimetidine was compared to oral antacid premedication in 17 patients undergoing elective Caesarean section. Seven patients in the Cimetidine group and four in the antacid group had gastric volumes in excess of 50 ml after induction of anaesthesia, while two patients in each group had gastric pH less than 2.5 after induction. Cimetidine was as effective as antacid in raising gastric pH but neither was completely reliable. This study reconfirms the high gastric volumes in pregnant patients with the need for preventative measures against aspiration during the induction of anaesthesia. 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) In a prospective controlled study 30 parturients provided for elective cesarean section were premedicated either with no specific medication for prophylaxis of aspiration pneumonia or 400 mg cimetidine orally at the evening and 400 mg intramuscularly two hours prior to induction of anesthesia. In the cimetidine treated group only one patient had a gastric pH below 2.5, while in the control group 11 patients had a pH below this limit. The gastric volume in the cimetidine treated group also was significantly reduced. No side effects could be observed in mothers and children. Application of intramuscularly cimetidine seems to be an effective method for prophylaxis of aspiration pneumonia in obstetric anesthesia. This study compares the efficacy of omeprazole and ranitidine at reducing gastric secretion in obstetric patients. Sixty-five women scheduled to undergo elective Caesarean section under general anaesthesia were randomly allocated to receive either omeprazole 40 mg or ranitidine 150 mg orally at 2200 hours the night before and at 0600 hours on the morning of surgery. Intragastric pH and volume were measured immediately after induction of anaesthesia and on completion of surgery. All patients had gastric aspirates less than 25 ml. None of the omeprazole group had an aspirate of pH less than 3.5. Six patients (19%) in the ranitidine group had aspirates of pH less than 3.5, a significant difference from the omeprazole group (p less than 0.05). Of these six, two (6%) had aspirates of pH less than 2.5. Hence this study showed that omeprazole was more effective and consistent than ranitidine at maintaining gastric pH greater than 3.5. 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. 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.