Omeprazole reduces preoperative gastric fluid acidity and volume in children

To explore the effects of oral omeprazole on preoperative gastric fluid pH and volume in children, 104 healthy in-patients aged 4–9 yr were randomly allocated to four groups (n = 26). Subjects in the Omeprazole-Omeprazole Group received two doses of omeprazole (20 mg per dose), those in the Placebo-Placebo Group, two doses of placebo, those in the Placebo-Omeprazole and Omeprazole-Placebo Groups, one dose each of the two preparations by mouth. For each treatment regimen, the first medication was administered at 9:00 p.m. on the night before surgery and the second at 5:30 a.m. on the morning of the day of surgery (three hours preoperatively). Children undergoing elective surgery were offered 10 nil · kg^?1 of apple juice three hours before induction of anaesthesia. After induction of anaesthesia and tracheal intubation, gastric fluid was aspirated through a large-bore, multiorifice orogastric tube and analyzed for pH and total fluid volume. The administration of omeprazole at bedtime before surgery increased gastric pH (3.3 ± 1.3 vs 2.0 ± 0.6, P < 0.05) in comparison with placebo, as did two doses of omeprazole (pH = 4.8 ± 1.6, P < 0.05). A single dose of omeprazole administration on the morning of the day of surgery failed to increase gastric pH. There was a reduction in the number of children with a pH < 2.5 and a volume > 0.4 ml · kg^?1 in the Omeprazole-Omeprazole and Omeprazole-Placebo Groups compared with the Placebo-Placebo or Placebo-Omeprazole Groups. Oral omeprazole 20 mg administered on the night prior to surgery will improve the gastric environment at the time of induction of anaesthesia, thus reducing the potential risk of pneumonitis, should the aspiration of gastric contents occur following the induction of anaesthesia. These data also suggest that this drug, when administered in a single dose of approximately 1.0 mg · kg^?1 three hours before surgery, is ineffective in increasing gastric fluid pH to > 2.4.     

Omeprazole for prophylaxis of acid aspiration in elective surgery

The aim of the study was to determine whether a single oral dose of omeprazole 40 mg is effective in increasing the pH of gastric residue above 2.5 at the time of anaesthetic induction in adult patients scheduled for elective gynaecological surgery. The patients were allocated to receive either chlorazepate dipotassium 25 mg alone or omeprazole 40 mg and chlorazepate dipotassium 25 mg on the night before surgery. Gastric volume and pH were measured after induction of anaesthesia. Patients who received omeprazole had a higher mean pH than control patients (p less than 0.001). The pH was less than 3.5 in 50% of patients in the control group, but in only 4.5% of those who received omeprazole (p less than 0.01). Mean (SEM) volume of gastric fluid was 15.2 (2.7) ml in the control group and 9.2 (1.8) ml in the omeprazole group, but the results were not statistically significant. A single dose of 40 mg omeprazole significantly decreased the number of patients at risk of aspiration pneumonitis.     

Effect of preoperative paracetamol on gastric volumes and pH in children.

The effect preoperative paracetamol elixir has on gastric contents is unknown. Children presenting for elective adenotonsillectomy were randomized to receive either paracetamol elixir (40 mg x kg(-1)) 90 min before surgery or paracetamol suppositories (40 mg x kg(-1)) intraoperatively. Following induction of anaesthesia a 16 Fr multiple-oriface orogastric tube was passed into the stomach and measure taken of the residual gastric volume and pH. The children had a mean age of 8.5 years (SD 3.2) with a weight of 35 kg (SD 16.5). Children given elixir (n=41) had a mean residual gastric volume of 0.083 ml x kg(-1) (95% CI; 0.006, 1.24) and a pH of 1.83 (95% CI; 0.75, 4.49), while those given suppositories (n=40) had a mean residual gastric volume of 0.083 ml x kg(-1)(95% CI; 0.008, 0.9) and a pH of 2.07 (95% CI; 0.84, 5.12). There was no significant difference between these two groups. Paracetamol elixir is rapidly absorbed in the gastrointestinal system of children and preoperative administration has no effect on gastric contents. Given paracetamol's slow equilibration rate constant from the central to the effect compartment, children may be given this medication preoperatively for routine surgical procedures.     

Cisapride does not alter gastric volume or pH in patients undergoing ambulatory surgery

PURPOSE: To evaluate the efficacy of 20 mg cisapride p.o. in reducing residual gastric volume and pH in adult ambulatory surgical patients. METHODS: Using a prospective randomised double-blind controlled design, we administered either 20 mg cisapride p.o. or placebo preoperatively to 64 ASA 1-2 ambulatory surgical patients. Following induction of anesthesia we measured volume and pH of residual gastric contents, using blind aspiration through an orogastric tube. Parametric data were analysed using unpaired, one tail Students' t test. Non-parametric data were analysed using Fishers Exact test and Chi square analysis. Statistical significance was accepted at the probability level of < 0.05. RESULTS: Residual gastric volumes were similar in the two groups (19.5 +/- 23.8, 23.9 +/- 24.4 ml), in the cisapride and placebo groups respectively, P=0.24). Data shown are mean (+/- SD). The proportions of patients with a residual gastric volume exceeding 0.4 ml x kg(-1) were similar in the two groups (4 of 28, and 8 of 23 patients in the cisapride and placebo groups respectively, P=0.09). The pH of the residual gastric contents were similar in the cisapride and placebo groups (1.6 +/- 0.5, 1.4 +/- 0.5, respectively, P=0.26). The proportions of patients with pH < 2.5 was also similar in the cisapride and placebo groups (21 of 25, and 20 of 21 patients respectively, P=0.2). CONCLUSIONS: Preoperative administration of 20 mg cisapride p.o. to patients scheduled for outpatient surgery does not alter either the volume or the pH of gastric contents. Its use in this setting is of no apparent clinical benefit.     

Interactions of preoperative erythromycin administration with general anaesthesia

Previous reports have demonstrated a gastric emptying effect of erythromycin due to a motilin-like mechanism. We studied 50 patients, scheduled for daycase laparoscopy, randomly assigned to one of two groups: Group P patients received 30 min before induction of anaesthesia, in a double-blind manner an infusion of 250 ml dextrose 5% while patients in Group E (n = 25) received 500 mg of erythromycin diluted in 250 ml dextrose 5%. An orogastric tube was inserted to measure both gastric pH using a pHmeter and residual gastric volume (RG V) using the phenol red dilutional technique. Six patients were excluded for surgical reasons. More patients in Group P (6/22) than in Group E (0/22) had RGV > 25 ml and more patients in Group P (17/22) presented with a gastric pH < 2.5 than in Group E (5/22), P < 0.05. Since coma and respiratory depression have been reported recently after midazolam and alfentanil administration in patients having received erythromycin, recovery conditions were assessed and were found to be comparable between groups. In conclusion, the administration of iv erythromycin before outpatient laparoscopy decreased residual gastric volume and increased gastric pH without affecting recovery from general anaesthesia.     

Utility of premedication with different regimens of omeprazole and ranitidine in the prevention of acid broncho-aspiration syndrome]

OBJECTIVE. To study the usefulness of several omeprazole regimens on gastric fluid volume and pH in patients undergoing elective surgery. MATERIAL AND METHODS. We analyzed 105 patients undergoing to elective surgery who received prophylactic treatment for the acid aspiration syndrome. They were randomly allocated into 7 homogeneous groups according to the therapeutic regime. Placebo (group 1), oral omeprazole (20 mg) the night prior to surgery (group 2), oral ranitidine (150 mg) the night before (group 6), two doses (the previous night and before surgery) in the remaining three groups: 20 mg of omeprazole (group 4), 40 mg of omeprazole (group 5) or 150 mg of ranitidine (group 7). In all patients we measured pH and volume of the gastric content after induction of anesthesia and one hour thereafter. RESULTS. There were no statistically significant differences in mean pH values and gastric volume content among groups 1.2,3, and 6 (2.1 (pH) and 27 ml (gastric volume) in group 1, 2.1 and 23 ml in group 2, 2.6 and 19 ml in group 3, and 2.2 and 32 ml in group 6). With repeated doses of 40 mg omeprazol (group 5), mean pH values were comparable to those found with the two doses of ranitidine (4.1 +/- 1.8 vs 4.1 +/- 3.6) although gastric volumes were significantly less (12 +/- 2.6 ml vs 20 +/- 4.8 ml). These two groups showed significantly greater mean pH values and less gastric volumes than the remaining patients. CONCLUSIONS. The incidence of patients with gastric content deemed at risk for acid aspiration (pH less than 2.5 and gastric volume greater than 25 ml) was less after premedication with two oral doses of omeprazole (40 mg) than either two doses of ranitidine (150 mg) or smaller doses of both drugs.     

Preoperative anxiety and gastric fluid secretion in healthy children scheduled for outpatient surgery

Summary
A prospective study of otherwise healthy unpremedicated children scheduled for outpatient surgery was undertaken to determine the relationship between preoperative anxiety and gastric fluid volume and acidity in children. The anxiety level of the child, using a six point anxiety scale, was determined in the preoperative holding area 15–30 min before surgery. After induction of anaesthesia and tracheal intubation, a multi-port large bore catheter was inserted orally to aspirate gastric contents. Gastric fluid volume was measured and its pH was determined by an Accumet® 915 pH meter. One hundred and fifty patients, between 2 and 10 years of age (mean 5.3 ± 3.0 yrs), weighing 11.2–69.0 kg (mean 22.3 ± 15.4) were studied. Gastric contents could only be aspirated in 101 out of 150 patients. Gastric fluid volume averaged 0.41 ± 0.31 ml·kg⁻¹ in these 101 patients. The average pH was 1.54 ± 0.40. Thirty two patients (21%) had gastric fluid volume > 0.4 ml·kg⁻¹ and pH <2.5. Neither the gastric volume nor the pH correlated with the preoperative anxiety scores. We conclude that in otherwise healthy children undergoing outpatient surgery, preinduction anxiety does not affect gastric volume and/or acidity.     

A comparison of the effects of ranitidine and omeprazole on volume and pH of gastric contents in elective surgical patients

BACKGROUND AND OBJECTIVE: In cases of aspiration of gastric contents the risk of pneumonitis is dependent on the pH and volume of the gastric contents. Omeprazole and rantidine each decrease gastric volume and increase gastric pH. We evaluated the efficacy of preoperative administration of omeprazole (60 mg) or ranitidine (150 mg) in the prophylaxis of aspiration pneumonitis. METHODS: Data were obtained from 75 elective female surgical patients randomly allocated to one of three groups, who received either omeprazole 60 mg orally, or ranitidine 150 mg orally, or neither, on the evening prior to, and on the morning of, surgery. Gastric volume and pH was measured using blind aspiration. RESULTS: Both pH < 2.5 and volume > 25 mL were present in none of the patients in either the ranitidine or omeprazole groups, compared to 15 of 25 control patients (P < 0.0001). CONCLUSIONS: Preoperative oral administration of omeprazole (60 mg) or ranitidine (150 mg) reduced residual gastric content volume and increased pH > 2.5, possibly reducing the effects of pulmonary aspiration of gastric contents.     

A comparison of intravenous ranitidine and omeprazole on gastric volume and pH in women undergoing emergency Caesarean section

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. Une étude à double insu nous a permis de comparer l’effet de l’oméprazole et de la ranitidine sur le contenu gastrique de 80 parturientes subissant une césarienne d’urgence. Au moment de h prise de décision en faveur de la césarienne, les patientes ont été réparties aléatoirement pour recevoir soit de la ranitidine 50 mg, soit de l’oméprazole 40 mg par la voie intraveineuse. Le volume et le pH du contenu gastrique ont été mesurés immédiatement après l’intubation et avant l’extubation. Le pH gastrique était plus élevé après l’oméprazole qu’après la ranitidine immédiatement après l’intubation (respectivement 5,89 ± 1,46 et 5,21 ± 1,36, P < 0,05) et avant l’extubation (respectivement 5,97 ± 1,38 et 5,32 ± 1,24, P < 0,05). Cependant, le volume gastrique était comparable entre les deux groupes. Après l’intubation, le nombre de patientes avec un volume gastrique > 25 ml et un pH <2,5 était de trois (7,5%) dans le groupe ranitidine, et de une (2,5%) dans le groupe omeprazole et d’aucune des deux groupes avant l’extubation. Les auteurs concluent que l’oméprazole 40 mg iv administré au moment de la décision d’opérer procurait un pH gastrique plus élevé que la ranitidine chez des parturientes subissant une césarienne en urgence.     

Comparison of the effect of two dose schedules of oral omeprazole with oral ranitidine on gastric aspirate pH and volume in patients undergoing elective surgery

We have compared gastric aspirate pH and volume at induction of anaesthesia in 222 patients who had received either omeprazole or ranitidine before elective operations. Omeprazole was given orally either as 40 mg on the evening before and 40 mg on the morning of surgery or as 80 mg on the morning of surgery. Ranitidine 150 mg was given orally on the evening before surgery and 2 h before anaesthesia. Treatment success was defined as aspirate pH > or = 2.5 and volume < 25 ml at induction of anaesthesia. Treatment was successful in 84% (95% confidence interval (CI) 73-91%) of patients in the omeprazole 40 + 40 mg group, 84% (95% CI 73-91%) in the ranitidine group and 73% (95% CI 61-83%) in the omeprazole 80 mg group. There were no statistically significant differences between the groups. Twelve patients in the omeprazole 80 mg group had gastric pH < 2.5 and four had volume > 25 ml. Only three patients had a gastric pH < 2.5 in the omeprazole 40 + 40 mg group and none had volume > 25 ml, which compared well with the ranitidine group. Omeprazole, given as 40 mg in the evening and 40 mg on the morning of operation, has a potential role for use in patients at risk for aspiration during general anaesthesia.      

Effect of single-dose omeprazole and ranitidine on gastric juice acidity and volume in patients undergoing laparotomy

The effects of oral omeprazole and oral ranitidine on gastric fluid volume and pH were compared in 95 elective surgical patients, randomly assigned to one of three groups. The patients received either 80 mg of omeprazole or 300 mg of ranitidine orally at 6.00 on the morning of surgery. One third of the patients received no antacid therapy. Following induction, a no. 18 nasogastric tube was passed into the stomach and all available gastric fluid was aspirated. pH and volumes were measured. In the omeprazole- and ranitidine-treated groups, the mean pH was > 5.4 after induction, at completion of surgery and 1 h after operation, although at least one patient in both groups had pH < 2.5. The volumes of gastric aspirates were reduced equally by both drugs. Two patients in the omeprazole group, none in the ranitidine group and eight in the control group (26%) had pH <2.5 with volume> 25 ml at induction. Both drugs appeared to be effective in reducing the volume of intragastric fluid and acidity to acceptable values.     

The efficacy of ranitidine in children

The effect of preoperative oral ranitidine on intragastric pH and volume of aspirate was evaluated in anaesthetized children. Five groups of eight randomly assigned children were evaluated. The first group acted as control and the other groups received 2, 2.5, 3, 3.5 mg kg-1 ranitidine, respectively. The drug was administered 1-4 h preoperatively. The intragastric pH was measured by a pH electrode through an orogastric tube, and the volume of aspirate was recorded every hour. At the time of first measurement oral ranitidine was significantly effective (P less than 0.001) in increasing the pH of intragastric contents to above the safe level of 2.5 in 94% of the children. At the second measurement an hour later, it was effective in all the children. Ranitidine has no significant effect on the volume of gastric aspirate and also there was no significant difference in the effect on the pH of the various doses of ranitidine studied. Oral ranitidine at doses of 2-3.5 mg kg-1 is effective in decreasing gastric acidity in children.     

Fluid deprivation before operation

The effect of oral fluids before operation, followed by intramuscular morphine, on gastric volume and pH was examined in 150 elective surgical patients, ASA physical status 1 and 2, who were randomly assigned to one of the three groups of 50 each. Group 1 (control) continued their overnight fast; patients in Groups 2 and 3 received 150 ml water 2 hours before the scheduled time of surgery. Patients in Group 3 received intramuscular morphine 0.15 mg/kg and promethazine 0.5 mg/kg one hour before operation. The residual gastric volume was obtained by suction and its volume and pH measured immediately after induction of anaesthesia. Statistically significant (p less than 0.05) decrease in residual gastric volume was observed in Groups 2 and 3 as compared to Group 1. However, the difference between these two groups was not statistically significant. There was no statistically significant difference in pH among the three groups. Overnight fluid fasting is not justified in elective surgical patients. Morphine can be safely given one hour before surgery in patients who have received water (150 ml) 2 hours before operation.     

Oral premedication with midazolam in paediatric anaesthesia. Effects on sedation and gastric contents

The aim of this study was to assess oral premedication with midazolam in paediatric anaesthesia. Sedation, quality of induction, recovery time, acceptance and effects on gastric contents were analysed. This prospective, double blind, at random and controlled study was performed in 107 children, aged between three and ten years. They were divided into: group 1 (control, n=29), group 2 (placebo) receiving 5 ml of water in the preoperative stage (n=40), and group 3 (midazolam) with 0.75 mg·kg^-1 midazolam by mouth (n=38). Two children refused to take medication. In children aged five years or more (n=48) of groups 2 and 3, acceptance of premedication was evaluated. The midazolam group showed a better level of sedation as compared with the placebo (P<0.05). The recovery time was similar for the two groups. There were no statistically significant differences in gastric pH or residual volume among the three groups. It is concluded that midazolam given by mouth is an efficient and safe drug for premedication in paediatric anaesthesia.     

Use of omeprazole for premedication]

Omeprazole, a proton pump inhibitor was used for premedication for general anesthesia, and its effects on gastric secretion and serum gastrin level were investigated in 60 patients. The patients were divided into the following 4 groups and each group received one of the following medications; (I) a tablet of omeprazole 20 mg before sleep at the night before the surgery, (II) a tablet 2 hours before the induction of anesthesia, (III) one on the night before and another tablet 2 hours before the induction, or (0) no tablet. In the patients who received any dose of the drug, the volume of gastric juice at the beginning of the surgery was significantly less than that in those who received no drug (P less than 0.05). Gastric pH showed a tendency to increase depending on the dose of omeprazole (0 less than I less than II less than III), but it was not significant. No significant change in serum gastrin level was observed in this study. A 20 mg omeprazole tablet may not be adequate as the premedication for general anesthesia.     

Premedication with cimetidine and metoclopramide

A randomised, double-blind, placebo-controlled parallel study was conducted in adult females to evaluate the efficacy and safety of a combination of cimetidine 300 mg orally and metoclopramide 10 or 20 mg intravenously in reducing pre-operative residual gastric volume and raising gastric pH. The effect of preoperative metoclopramide on postoperative nausea and vomiting was also investigated. Oral cimetidine was given approximately 2-2.5 hours before, and intravenous metoclopramide either 15 or 30 minutes prior to induction of anaesthesia. The study showed that placebo-treated patients undergoing outpatient operations have an increased risk of acid aspiration because of high residual gastric volume and low pH and increased risk of serious pulmonary injury should acid aspiration occur. Metoclopramide 10 or 20 mg intravenously prior to induction of anaesthesia was effective in reducing the residual gastric volume significantly, but not in raising pH. The combination of cimetidine and metoclopramide, as well as cimetidine alone, reduced the risk factors of acid aspiration by raising gastric pH and reducing residual volume. No anti-emetic effect of metoclopramide was observed. Higher doses of metoclopramide (20 mg) produced significant side effects (flushing, dizziness, extrapyramidal side effects), but were only marginally more effective than 10 mg doses in reducing residual gastric volume.     

Omeprazole is more effective than a histamine H2-receptor blocker for maintaining a persistent elevation of gastric pH after colon resection for cancer

BACKGROUND: An assessment was made of the change and the effect of a histamine H(2)-receptor blocker (H(2)-blocker) or omeprazole on gastric pH after surgery. METHODS: Eighty patients who underwent colon resection for colorectal cancer were divided into groups of 20. Group I received neither H(2)-blocker nor omeprazole. Group II received cimetidine hydrochloride 1,200 mg daily, group III received ranitidine hydrochloride 200 mg daily, group IV received omeprazole 40 mg twice daily for 5 days. Gastric juice was measured preoperatively and then twice daily until the fifth postoperative day. RESULTS: The gastric pH decreased after surgery. The gastric pH increased on the first postoperative day after the administration of H(2)-blockers (P <0.001), but started to decrease on the second postoperative day. The gastric pH increased and remained high throughout the study period for the omeprazole group (P <0.001). CONCLUSIONS: The administration of an H(2)-blocker can significantly elevate the gastric pH value for patients after resection of colorectal cancer, but only lasts for 24 to 48 hours. Omeprazole is more effective than an H(2)-blocker at maintaining a persistent elevation of gastric pH.     

Gastric fluid volume and pH in elective patients following unrestricted oral fluid until three hours before surgery

This clinical study was designed to assess the results of new preoperative fasting guidelines in which patients are instructed that they must not eat any solid food after midnight, but that they may drink unrestricted amounts of clear fluid until three hours before their scheduled time of surgery. We studied 199 healthy, elective surgical inpatients aged 18– 70 yr to determine whether there was any corrélation between the ingestion interval or the volume of fluid ingested, with the volume and pH of residual gastric fluid at induction of anaesthesia. Pregnant patients, and those with gastric disorders or who were taking medications that affect gastric motility or secretion, were excluded. Either no premedication was given, or oral diazepam 5– 15 mg was given 90 min preoperatively. Of the 199 patients, 105 ingested 50– 1200 ml on the morning of surgery. The ingestion-induction interval was less than three hours in 12 patients whose actual surgery time was ahead of schedule. The remaining 94 patients did not drink because they were scheduled for surgery before 11:00 (n = 51), they did not want to drink (n = 24), or they were advised not to drink by their nurse or surgeon (n = 16). Following induction of anaesthesia, gastric fluid was aspirated through a #18 Salem sump orogastric tube, the volume was recorded and pH was measured with à calibrated pH meter. Patients were divided retrospectively into four groups (in three of which patients ingested fluid) according to the ingestion-induction interval (1.3– 3.0 hr, 3.1– 5.0 hr, 5.1– 8.0 hr, and nothing by mouth after midnight). Values (mean ± SD) for residual gastric fluid volume (22 ± 19, 32 ± 26, 28 ± 19, 25 ± 19 ml) and pH (1.5 ± 0.3, 1.7 ± 1.3, 1.6 ± 1.1, 1.6 ± 0.9) showed no statistically significant differences among the four groups. Within each of the three fluid groups there was no correlation between volume of fluid ingested and residual gastric fluid volume. We conclude that healthy inpatients should be allowed to ingest unrestricted clear fluid until three hours before the scheduled time of surgery.     

A comparison of the effects of omeprazole with those of ranitidine on intragastric pH and volume in patients for elective surgeries]

This study compared the effect of omeprazole with those of ranitidine on intragastric secretion during perioperative period. Thirty-one patients were randomly allocated to three groups. Each group received either omeprazole, ranitidine orally or one on the night before surgery. Intragastric pH and volume were measured after induction of anesthesia. Omeprazole group and ranitidine group had a higher mean pH than control group (P less than 0.01). None of the omeprazole group had an aspirate of pH lower than 2.5. One patient (10%) in the ranitidine group and five patients (50%) in the control group and five patients (50%) in the control group had aspirates of pH lower than 2.5. Mean gastric volume was not significantly different among these groups. A single dose of omeprazole 20 mg significantly decreased the number of patients at risk of aspiration pneumonitis.