Gastric volume and pH in out-patients.

We measured the volume and pH of the gastric content of 21 out-patients and 21 in-patients under general anaesthesia. Gastric tubes were inserted after induction of anaesthesia, and gastric fluids were withdrawn for pH determinations. Gastric volumes were measured by a dilution technique using polyethylene glycol as the indicator and also by measurement of the volume aspirated through a gastrict tube. Out-patients had a mean gastric volume of 69 +/- 17 ml while in-patients had a mean volume of 33 +/- 4 ml. The average gastric pH for the out-patients was 1.8 +/- 0.2 and for the in-patients 2.0 +/- 0.3. Four out-patients had more than 75 ml of gastric fluid of pH less than 2.0. Aspiration through a gastrict tube did not empty the stomach completely and the volume thus obtained gave a falsely low estimate of the gastric volume.     

Gastric fluid pH in patients receiving cimetidine

Gastric fluid pH was measured immediately after anesthetic induction in 150 fasted adult patients with or without prior cimetidine. All patients had received morphine-atropine preanesthetic medication. Gastric fluid pH was above 2.5 in 39/50 patients (78%) receiving cimetidine 300 mg orally with 50 ml H2O the evening before operation. The same dose of oral cimetidine but 60 to 90 minutes before anesthetic induction resulted in gastric fluid pH above 2.5 in 42/50 patients (84%). In contrast, gastric fluid pH was above 2.5 in only 20/50 patients (40%) not receiving cimetidine. We conclude that oral cimetidine administered 60 to 90 minutes before anesthetic induction is a practical way to increase gastric fluid pH above 2.5 in the majority of fasting adult patients.     

Gastric fluid volume pH,and emptying in elective inpatients Influences of narcoticatropine premedication oral fluid,and ranitidine

One hundred and twenty healthy, elective surgical inpatients were randomly assigned to one of four groups. Between two and three hours before the scheduled time of surgery all patients ingested a marker dye, phenol red, 50 mg in 10 ml water, with placebo tablet alone (Groups 1 and 2), placebo tablet with 150 ml oral fluid (Group 3), or oral ranitidine 150 mg with oral fluid 150 ml (Group 4). Patients in Group 1 received oral diazepam or no premedication, while those in Groups 2, 3, and 4 received IM narcotic and atropine one hour preoperatively. Following induction of anaesthesia the residual gastric fluid was aspirated through a Salem sump tube and its volume, pH, and phenol red content measured. Mean volumes were Group 1: 24 ml; Group 2: 13 ml; Group 3: 17 ml; Group 4: 14 ml. Mean pH values were Group 1: 2.99; Group 2: 3.03; Group 3: 3.44; Group 4: 5.28. The amount of phenol red in the samples indicated at least 90 per cent gastric emptying had occurred in 90 per cent of patients. We conclude that, in healthy patients, 150 ml oral fluid is almost completely emptied from the stomach within two hours of ingestion, even when followed one hour later by narcotic-atropine premedication.     

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.     

Gastric fluid volume and pH in elective inpatients. Part II: coffee or orange juice with ranitidine

Afin ďévaluer ľeffet de ľingestion orale en période préopératoire de liquide, avec ou sans ranitidine, sur le volume de liquide gastrique ainsi que son pH; 300 patients admis pour chirurgie élective classe I ASA et II ont été randomisés en six groupes. Les trois groupes ranitidine (groupe 4, 5 et 6) son! discutés dans cet article (partie II, et les trois groupes placebo (groupe I, 2 et 3 sont discutés) dans la première partie. Entre deux et trois heures avant le temps cédulé pour la chirurgie les patients ont re?u 150 ml de café avec de la ranitidine par voie orale 150 mg (groupe 4), 150 ml de jus ďorange avec de la ranitidine par voie orale 150 mg (groupe 5), ou de la ranitidine seule (groupe 6). Aucune prémédication aux opiacés ou belladone n’a été administree. Immédiatement après ľinduction de ľanesthésie un tube #18 Salem sump a été introduit et sa position dans ľestomac a été confirmée par auscultation après insufflation ďair. Le volume gastrique résiduel aspiré avec une seringue de 60 ml a été enregistré et son pH mesuré. 11 n’y avail aucune différence statistiquement significative entre les groupes par rapport au volume (groupe 4:14.3 ± 15.4; groupe 5: 14.8 ± 17.0; groupe 6; 9.7 ± 12.6 ml). Le pH moyen dans tous les groupes était supérieur a 5.40 (groupe 4: 5.65 ± 2.12; groupe 5:5.41 ± 2.12; groupe 6: 6.21 ± 1.51).     

Gastric fluid volume and pH in scheduled surgical patients following unrestricted oral fluid intake until two hours before surgery

BACKGROUND: In scheduled surgery, drinking is generally restricted for 6-8 hours before operation to avoid aspiration pneumonia induced by aspiration of residual gastric contents. However, the restriction is hard for patients and also there is no evidence of reduction of such a risk. We examined the correlation between water intake and residual gastric content. METHODS: We studied 60 patients scheduled for gynecological operations (ASA 1 or 2). They were allowed to drink clear water freely until two hours before operation, and timing and volume of their drinking were recorded. In addition, volume and pH of the residual gastric content were measured at induction of anesthesia. RESULTS: The mean volumes of fluids they had are 157 ml (range 0-750 ml) in the morning, and 486 ml (range 80-1300 ml) in the afternoon. The patients took more water as the scheduled time of operation became nearer. There was no correlation between the volume of preoperative drinking with the volume and pH of gastric content. CONCLUSIONS: Intake of clear water until two hours before surgery has been shown to be safe and contribute to patients' satisfaction.     

Gastric fluid volume in infants for pyloromyotomy

Purpose

To quantify gastric fluid volumes in infants with pylonc stenosis presenting for pyloromyotomy and to demonstrate endoscopically the efficacy of blind aspiration for gastric fluid recovery. We hypothesized that previous diagnostic contrast studies, preoperative nasogastric suction, and fasting interval would not affect these volumes.

Methods

Seventy-five infants scheduled for pyloromyotomy were given atropine before induction of anaesthesia. For those who had undergone preoperative nasogastric suction, the nasogastric tube was aspirated and removed. A 14 F multionficed orogastric catheter was blindly passed to aspirate gastric fluid for measurement. Following tracheal intubation. I 5/75 subjects underwent gastroscopy to measure residual gastric fluid.

Results

Gastric fluid volume removed by blind aspiration averaged 4.8 ± 4.3 ml·kg^?1 with 83% of patients having > 1.25 ml·kg^?1. Although 14 of the 15 patients evaluated by endoscope had ≤ 1 ml residual gastric fluid, one had 1.8 ml·kg^?1. Recovery of total gastric fluid volume by blind aspiration averaged 96 ± 7%. The large gastric fluid volumes were independent of a history of banum study, preoperative nasogastric suction, and fasting interval.

Conclusion

Infants with pylonc stenosis have large gastric fluid volumes which are not substantially reduced by preoperative nasogastric suction. Blind aspiration of gastric contents prior to induction of anaesthesia provides a reliable estimate of total gastric fluid for most of these infants, although the occasional infant may retain a small amount of gastric fluid. The clinical importance of such a residual volume is uncertain.     

Gastric volume and pH in children for emergency surgery

The volume and pH of gastric contents aspirated prior to anaesthesia were measured in 101 children admitted for emergency surgery. The children were aged between 3 months and 15 years. If we define potential patients at risk by means of the volume and pH of the gastric contents, then 50.0% of the children were at risk of aspiration into the lungs. The number of patients at risk was higher in children aged between 6 and 10 years. There was almost the same risk in the groups with abdominal-, urogenital-, and orthopaedic diseases, while the number of patients at risk was less in the group with superficial lesions. The length of fasting time in the child considerably influenced the volume of gastric contents in emergency surgical cases. It is concluded that in children admitted for emergency surgery there is a risk of aspiration of gastric contents into the lungs. The risk is reduced by preanaesthetic fasting. All children admitted for emergency surgery must be carefully evaluated prior to anaesthesia with special reference to gastric aspiration.     

Gastric fluid volume and pH after nizatidine in adults undergoing elective surgery: influence of timing and dose

We conducted a prospective, randomized, double-blind study to investigate the effect of oral nizatidine (150–600 mg), a new potent H₂ antagonist, on preoperative gastric fluid pH and volume in adults undergoing elective surgery. One hundred and seventy-five healthy adults (21–68 yr) were randomly allocated to seven treatment groups (n = 25); Placebo was administered at 21.00 and 06:30 the night before and on the day of surgery, respectively (0/0: control); nizatidine 150 mg at 21.00 and placebo at 06:30 (150/0); placebo at 21.00 and nizatidine 150 mg at 06:30 (0/150); nizatidine 150 mg at 21:00 and 06:30 (150/150); nizatidine 300 mg at 21.00 and placebo at 06:30 (300/0); placebo at 21.00 and nizatidine 300 mg at 06:30 (0/ 300); and nizatidine 300 mg at 21.00 and 06:30 (300/300). Each patient fasted overnight and took the drug and/or placebo with 20 ml water. After induction of anaesthesia, the pH and volume of gastric fluid obtained through an orogastric tube were measured, the mean pH of 0/150, 150/150, 300/0, 0/300, and 300/ 300 groups was higher than that of the control group (P < 0.05). Gastric volume in these groups was smaller than in the control (P < 0.05). The 150/0 group failed to decrease gastric fluid volume and increase pH. In the 300/0 group, the gastric pH was lower than other regimens which effectively decreased gastric acidity (P < 0.05). The number of patients with a pH < 2.5 and a volume >0.4 ml · kg^?1 in the 0/150, 150/150, 0/300, and 300/300 groups (0%) was less than in the control group (16%) (P < 0.05). These data suggest that oral nizatidine in a dose of ≥ 150 mg given on the morning of surgery decreases preoperative gastric acidity.     

Prevention of aspiration pneumonia in obstetrical anesthesia with the effervescent combination of cimetidine and sodium citrate

The effect of an oral effervescent formulation combining 200 mg cimetidine and 1.8 g sodium citrate on gastric pH and volume were studied in patients undergoing caesarean section. Seventy-four patients undergoing elective (group 1) or emergency caesarean section (group 2) were included. Before entering the operating theater (5 to 60 min before intubation), they were given the tablet dissolved in 15 ml of water. Induction and maintenance of anaesthesia were carried out with conventional techniques. The patient's gastric content was aspirated just after endotracheal intubation, and before extubation. its pH and volume were measured at both times. Mean pH was similar in the two groups after intubation (6.07 +/- 1.13 in group 1; 5.52 +/- 1.14 in group 2) and before extubation (6.32 +/- 1.08 vs. 5.85 +/- 1.02 respectively). Gastric pH was therefore greater than 2.5 in all 74 patients at both times. Mean volumes of gastric content after intubation were greater in group 2 (32.7 +/- 23.9 ml vs. 21.6 +/- 15.8 ml; p less than 0.02). However, just before extubation, these were similar (15.0 +/- 15.4 ml in group 1, 20.1 +/- 14.9 ml in group 2). The percentage of patients in the 2 groups with gastric volumes greater than 25 ml at the time of intubation were not significantly different (29.7% vs. 45.9% respectively). No patient was at risk of developing pneumonitis in case of aspiration (gastric content pH less than 2.5 and volume greater than 25 ml), either during endotracheal intubation or extubation.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of intravenous cimetidine and metoclopramide on gastric pH and volume in outpatients

STUDY OBJECTIVE: To evaluate and compare the preinduction effects of intravenously (IV) administered cimetidine alone and combined with metoclopramide on gastric contents and postoperative nausea and vomiting in outpatients undergoing elective surgery. DESIGN: Patients were allocated randomly to 4 groups with 20 patients in each group. SETTING: Ambulatory surgery at a university-affiliated city hospital. PATIENTS: Eighty patients undergoing elective gynecologic or orthopedic procedures were studied. INTERVENTIONS: Outpatients in Group 1 and inpatients in Group 2 served as controls. Outpatients in Group 3 received 300 mg of cimetidine, and outpatients in Group 4 received 300 mg of cimetidine and 10 mg of metoclopramide. All drugs were administered IV as an infusion over a 15-minute period, 30 to 45 minutes prior to induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: After induction of general anesthesia and endotracheal intubation, stomach contents were retrieved and volume and pH measured. Group 1 outpatients had a large residual gastric volume of 29.2 +/- 15.9 ml, with a very low pH of 2.32 +/- 1.23 and 15% frequency of postoperative vomiting. These patients are at high risk of developing significant pneumonitis in the event of the aspiration of gastric contents. The combination of cimetidine and metoclopramide in Group 4 provided the optimal, or safest, condition--i.e., high gastric pH [6.15 +/- 0.71 (p less than 0.005)] and low gastric volume [11.6 +/- 7.37 ml (p less than 0.001)], with no postoperative vomiting. CONCLUSIONS: The combination of cimetidine and metoclopramide given to ambulatory patients during the preinductive phase may prevent severe pulmonary consequences should aspiration occur and is more effective in this regard than cimetidine alone.     

Effects of oral cimetidine and ranitidine on gastric pH and residual volume in children

The effect of orally administered cimetidine 7.5 mg/kg (group 1), ranitidine 1.5 mg/kg (group 2), ranitidine 2.0 mg/kg (group 3), or a placebo (group 4) on gastric pH and gastric residual volume of 60 healthy children 2-6 yr of age admitted for elective surgery was evaluated. Both cimetidine and ranitidine administered 1-2 h prior to induction of anesthesia effectively increased the gastric pH:5,47 - 1.85 ml/kg (group 1), 4.92 +/- 2.1 ml/kg (group 2), 5.30 +/- 1.82 ml/kg (group 3) compared with 1.75 +/- 0.58 ml/kg (group 4) (P less than 0.001). A single dose of ranitidine 1.5 mg/kg was an effective as ranitidine 2.0 mg/kg and cimetidine 7.5 mg/kg. Neither drug decreased the gastric residual volume: 0.32 +/- 0.33 ml/kg (group 1), 0.31 +/- 0.06 ml/kg (group 2), 0.23 +/- 0.05 ml/kg (group 3), and 0.33 +/- 0.05 ml/kg (group 4). The combination of a volume greater than 0.4 ml/kg and a pH less than 2.5 was found in 33% (five of 15) of patients in the placebo group (group 4). In contrast, there were no patients with this combination in groups 1, 2, or 3 (P less than 0.001).     

Gastric fluid volume and pH in elective surgical patients: triple prophylaxis is not superior to ranitidine alone

The effect of oral ranitidine alone was compared with sequentially administered ranitidine, metoclopramide, and sodium citrate on gastric fluid volume and pH in 196 healthy, elective surgical inpatients, each of whom was randomly assigned to one of four groups. Patients in all groups received oral ranitidine 150 mg 2-3 hr before the scheduled time of surgery. Those in Group 1 also received oral metoclopramide 10 mg one hour before surgery, and sodium citrate 0.3 M 30 ml on call to the operating room; Group 2 received sodium citrate but no metoclopramide; Group 3 received metoclopramide but no sodium citrate; Group 4 received ranitidine alone. Following induction of anaesthesia a #18 Salem sump tube was passed into the stomach and all available gastric fluid was aspirated. Volumes were recorded and pH measured. In all groups mean pH was greater than 5.8, although at least one patient in each group had pH less than 2.5. Mean volumes were significantly greater in patients who received citrate (Groups 1 and 2: 22 and 19 ml) than in those in those who did not (Groups 3 and 4: 10 and 8 ml). One patient in Group 2 and one in Group 3 had pH less than 2.5 with volume greater than 25 ml. Our results do not demonstrate any advantage of double or triple prophylaxis over ranitidine alone. The practical difficulty of correctly administering two or even three medications, each at different but exact preoperative intervals, is emphasized.     

Effects of pre-anaesthetic glycopyrrolate and cimetidine on gastric fluid acidity and volume in children

The effects of pre-anaesthetic glycopyrrolate and cimetidine on gastric fluid pH and volume were studied in 96 paediatric patients from ages 6 months to 12 years undergoing elective surgery. They were randomly allocated into six groups with 16 patients in each group. Patients in group I received neither glycopyrrolate nor cimetidine and served as controls. Group II patients received glycopyrrolate, 5 micrograms kg-1 intramuscularly in a.m. Patients in group III received cimetidine 5 mg kg-1 orally in a.m. Group IV patients received cimetidine 5 5 mg kg-1 orally in a.m. and glycopyrrolate 5 micrograms kg-1 in a.m. Patients in group V received cimetidine 5 mg kg-1 orally h.s. and a.m. Group VI patients received cimetidine as in group V and also received glycopyrrolate as in group II. Patients with gastric pH 2.5 or less and volume of gastric contents 0.4 ml kg-1 or greater were defined to be at risk of pulmonary damage if aspiration should occur. The patients in the control group had a mean gastric pH of 1.91 +/- 0.074 and mean gastric volumes of 0.52 +/- 0.06 ml kg-1. Ninety-four per cent of patients in this group had gastric pH less than or equal to 2.5 and 69% of patients had gastric volumes greater than or equal to 0.4 ml kg-1. Glycopyrrolate (group II) reduced patients with pH less than or equal to 2.5 to 50% and volumes greater than or equal to 0.4 ml kg-1 to 44%. Cimetidine markedly reduced both gastric acidity (gastric pH less than or equal to 2.5 in 0-13% of patients in groups III-VI) and gastric volume (greater than or equal to 0.4 ml kg-1 in 19-38% of patients in groups III-VI). Only a maximum of 13% of the patients presented with combination of both risk factors in groups III-VI.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gastric pH and volume after oral fluids in the postpartum patient

The aim of this study was to investigate the relationship between preoperative oral fluids and gastric pH and volume in women undergoing sterilization between one and five days postpartum. Fifty postpartum patients received 150 ml water approximately two to three hours before surgery while 50 postpartum and 50 non-pregnant women were fasted from midnight. After induction of anaesthesia, gastric contents were aspirated using a Salem sump tube and the gastric pH and volume were measured. There were no differences in intragastric pH and volume, median (range), among the postpartum fasted group, 1.19 (0.74–4.57) 22 (1–78) ml, postpartum water group 1.18 (0.70–6.4), 25.5 (3–66) ml and the non-pregnant group 1.27 (0.51–6.63), 25 (3–69) ml. There was no correlation between postpartum interval, 60 (12–120) hr, and intragastric pH or volume. It is concluded that oral water may be given safely two to three hours preoperatively to patients more than one day postpartum. Intragstric volume and acidity were not increased and the findings in postpartum patients were similar to those found in non-pregnant patients.