Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Omeprazole is a substituted benzimidazole that causes dose-dependent intracellular inhibition of gastric acid secretion in humans. This double-blind study examined the effect of omeprazole in decreasing gastric acidity and gastric residual volume in outpatient adults. Unpremedicated outpatients, ASA I-III, 18 years or older (n = 17), were randomly assigned to receive omeprazole 80 mg, or placebo by mouth the night before scheduled elective outpatient surgery. The patients were fasted for 8 h prior to surgery. After the patient was anesthetized, an orogastric tube was inserted with proper placement verified by auscultation for gastric sounds. Gastric residual contents were withdrawn into a Luken's trap, and pH was then determined and gastric volume indexed to weight (ml.kg-1). Data were analyzed by a t-test, with P less than 0.05 considered statistically significant. Patient characteristics of both groups were similar. There was a statistically significant difference between the two groups for pH (P = 0.02), but not between the two groups for gastric volume indexed to weight (P = 0.07).
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PMID:Single-dose oral omeprazole for reduction of gastric residual acidity in adults for outpatient surgery. 851 11

This study documented gastric fluid acidity in ambulatory surgical patients 30-120 min after they had taken a 300-mg tablet of ranitidine, as changes specific to this relatively brief dose-to-sampling interval previously had not been delineated. At 20-120 min before outpatient surgery, ranitidine was given with 15 mL of water to 112 ASA physical status I-III adults without increased risk factors for aspiration of acidic gastric contents. After induction of general endotracheal anesthesia, the gastric fluid was aspirated. Volume and pH were compared with a reference group (pH = 1.6 +/- 1; n = 161) that did not receive an H2-antagonist or water. Of 40 patients sampled at 30-60 min after dosing, 26 had pH greater than or equal to 2.5; mean pH was 3.9 +/- 2 (P less than 0.05 vs reference by Wilcoxon signed rank and chi 2 tests). Beyond 90 min, 28 of 28 patients had a pH greater than or equal to 2.5, with a mean of 6.3 +/- 1. No significant differences were noted with respect to mean gastric volume. We conclude that in patients without additional risk factors, oral ranitidine consistently prevents acid production when it is administered more than 90 min before induction of anesthesia.
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PMID:Time required for oral ranitidine to decrease gastric fluid acidity. 195 80

Children undergoing general anesthesia are at increased risk of severe aspiration pneumonitis. Cimetidine and ranitidine, specific histamine (H2-receptor) antagonists, when given 1-3 h preoperatively markedly reduce the acidity and volume of gastric content. A newer compound, famotidine, is a more specific antagonist with no inhibitory effect on the drug metabolizing microsomal enzyme systems of the liver (cytochrome P-450), in contrast to cimetidine. An additional clinical advantage is a possible longer duration of action. In order to evaluate these potential advantages we studied the effects of preanesthetic oral famotidine on gastric fluid pH and volume in 4 groups in a random manner. METHODS. With parental consent, 107 infants and children (ASA I status, 4 months to 14 years old, NPO for at least 6 h) received either no famotidine (n = 29) or 0.15 mg/kg (n = 27), 0.3 mg/kg (n = 25) or 0.6 mg/kg (n = 26) famotidine at 7.00 a.m. Following induction by mask with nitrous oxide/oxygen (N2O/O2) and enflurane (E) or i.v. thiopental, intubation was performed in all patients. Anesthesia was maintained with N2O/O2 and E. A orogastric double-lumen tube was passed into the stomach, and the gastric content was aspirated in a uniform manner. Gastric volume was recorded and pH values were measured with pH paper. RESULTS. In the control group, 28 of 29 patients (97%) had a pH less than 2.5, 18/29 (62%) had a gastric volume greater than 0.4 ml/kg and 17/29 (59%) had a pH less than 2.5 and gastric volume greater than 0.4 ml/kg, meaning an increased risk of pneumonitis if the child aspirates the gastric content. Famotidine administration was effective between 1.5 and 6 h after oral administration. Preoperative famotidine application produces pH values of gastric contents higher than 2.5 in all dosage groups (84%, 94%, 75%), and these differences were highly significant (P less than 0.001), whereas the gastric volume reduction with these doses was not significant. The incidence of pH less than 2.5 and volume of gastric contents exceeding 0.4 ml/kg did not vary with the different doses of famotidine. As there were no measurable differences in the effect of famotidine, we recommend that children at high risk of pulmonary aspiration receive 0.15 mg/kg famotidine orally at least 1.5 h but not later than 6 h before induction.
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PMID:[Famotidine dosage in children. The effect of different doses on the pH and volume of the gastric juice]. 228 7

The Christiansen-Douglas-Haldane effect describes the reduced CO2 binding capacity of oxygenated as compared to deoxygenated hemoglobin on the basis of its increased acidity. This study describes the development of the above effect during the first 2 min of hyperoxic intubation apnea. METHODS. After institutional approval 12 patients (NYHA III, ASA IV) scheduled for coronary-artery bypass grafting were studied after written informed consent. Routine monitoring measures included invasive arterial and pulmonary-arterial pressure monitoring. Pulse oximetry (Nellcor N 101) was also used during intubation apnea. Premedication consisted of flunitrazepam 2.0 mg p.o. the evening before operation and another 2.0 mg p.o. 90-120 min before induction of anesthesia. Following standardized preoxygenation induction of anesthesia was performed with 20-25 micrograms/kg fentanyl and 0.1 mg/kg pancuronium. After cessation of spontaneous respiration, controlled ventilation was continued with 100% oxygen until intubation. Thirteen arterial (a) and mixed-venous (v) blood samples were drawn sequentially immediately before and during the first 2 min of apnea and analyzed using Corning 150 pH/blood gas analyzer and a Corning 2500 CO-oximeter. RESULTS. As shown in Table 1 and Fig. 1, paO2 decreased from 485 +/- 100 mmHg before apnea to 376 +/- 68 mmHg after 2 min of apnea while pvO2 remained constant at 47-50 mmHg. Arterial oxygen saturation (saO2) showed stable values greater than 97% while svO2 slightly increased from 81.9% to 82.4% until the end of apnea. A biphasic increase was observed in paCO2 from 41.2 +/- 3.4 mmHg before to 54.5 +/- 3.9 mmHg at the end of apnea. An increase in pvO2 during apnea was linear from 45.7 +/- 3.9 mmHg to 51.9 +/- 4.0 mmHg. After 28.5 s of apnea paCO2 exceeded pvCO2 due to the Haldane effect ("pCO2 reversal"). During apnea, pHa decreased biphasically from 7.40 +/- 0.03 to 7.31 +/- 0.02. The speed of decrease was 0.106 pH units/min (5-35 s) in the 1st and 0.023 pH units/min in the 2nd min of apnea; pHv decreased almost linearly from 7.37 +/- 0.03 mmHg (5s) to 7.33 +/- 0.02 mmHg (115s). After 20.66 s of apnea pHa exceeded pHv ("pH reversal"); pH-reversal occurred earlier than pCO2 reversal (p less than = 0.05). CONCLUSIONS. During early hyperoxic apnea, venoarterial pH and pCO2 reversal can be observed due to the Christiansen-Douglas-Haldane effect. pH reversal starts earlier than pCO2 reversal. Reversal time is dependent on arterial-mixed-venous pCO2 difference (avDpCO2) before apnea, arterial-mixed-venous O2 saturation difference (avDsO2) and cardiac output. The amount of reversal is dependent on avDsO2, i.e. the pH difference of arterial and m
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PMID:[The status of arterial and mixed venous blood gases in the initial phase of intubation apnea. Studies on the Christiansen-Douglas-Haldane effect]. 249 11

A study was made of the effect of rice chaff oil (ASA) on gastroduodenal ulcer (UGD) induced by different techniques: cysteaminium chloride, indomethacin, artificial gastric juices and stress (acidity, histamine, pepsin and volume of gastric juice were evaluated). For each technique the same protocol was followed: four days before the experiment 20 Wistar rats (180-220 g) were divided into a control group (0.2 ml/day of saline solution per os) and a treated group (0.2 ml/day of oral rice chaff oil). After quantitation of the ulcers and statistical analysis of the data, the ulcer index was found to be smaller in the treated group than in controls, both for stress ulcers (p less than 0.01) and for those induced by indomethacin (p less than 0.001) and artificial gastric juice (p less than 0.001). As for the cysteaminium chloride technique, an evaluation was made of the ulcer per se and the inflammatory halo; in both cases there were significant differences (p less than 0.05 and p less than 0.01 respectively) between the treated group and controls. No significant differences were found on comparing the values off histamine, pepsin and the volume of gastric juices, but there were differences in hydrogen ion concentration (p less than 0.05). An analysis is made of the physiologic aspects studied in each technique, emphasizing the possible implication of prostaglandins (PG) and alpha-tocopherol after treatment with rice chaff oil.
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PMID:[Antiulcerogenic properties of bran rice oil in rats]. 273 66

Aspirin induces gastric mucosal damage in animals and humans. The purpose of this study was to examine whether cimetidine protects the human gastric mucosa from acute aspirin-induced damage. Eight healthy subjects were studied on 4 separate days. Cimetidine, 400 mg, or placebo was given orally 1 hour before initial endoscopy. The stomach was isolated and atropine given to suppress basal acid secretion. Each study consisted of four 15 min periods during which an acidic test solution was instilled into the stomach. During the second period only, either aspirin (1300 mg, 36 mmol) or control for aspirin (36 mmol HCl) was added to the test solution. Ion fluxes and gastric mucosal potential difference were measured, and endoscopy performed following each test. After placebo, aspirin significantly altered hydrogen ion flux and potential difference versus basal and control. Cimetidine decreased the damaging effect of aspirin. Endoscopic scores increased after aspirin plus placebo, whereas they remained unchanged after aspirin plus cimetidine. Therefore, cimetidine decreased aspirin-induced gastric mucosal damage in humans. As gastric acidity was identical during all studies, the effect of cimetidine was independent of gastric acid secretion.
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PMID:Cimetidine decreases aspirin-induced gastric mucosal damage in humans. 297 81

Acid aspiration syndrome of induction of anesthesia is a life-threatening complication whose severity is affected by both pH and volume of the aspirated gastric juice. We compared the effects of two proton pump inhibitors (PPIs), lansoprazole and omeprazole, and an H2 blocker, ranitidine, on gastric secretion in a prospective, randomized, double-blind fashion in 200 adult patients of ASA physical status I undergoing elective surgery. The patients were divided into eight groups (n = 25 each) according to their premedication. The patients received lansoprazole-lansoprazole (Group L-L), lansoprazole-placebo (Group L-P), placebo-lansoprazole (Group P-L), omeprazole-omeprazole (Group O-O), omeprazole-placebo (Group O-P), placebo-omeprazole (Group P-O), placebo-ranitidine (Group P-R), or placebo-placebo (Group P-P), as the first and second medications. The dose of the study drug was 30 mg for lansoprazole, 150 mg for ranitidine, and 80 mg for omeprazole. The first medication was administered orally at 9:00 PM on the night before surgery and the second at 5:30 AM in the morning on the day of the surgery. Each patient fasted overnight and took the drug with 20 mL of water. After tracheal intubation, gastric fluid was aspirated via an orogastric tube and the volume and pH of the aspirate were measured. The pH of the aspirated gastric fluid was higher in Groups P-R, L-L, P-L, O-O, and O-P than in Group P-P (P < 0.05). The volume of the gastric contents was similar in Groups P-0 and P-P, and the other groups had smaller gastric volume than Group P-P (P < 0.05). Gastric fluid from patients in Group P-R was the least acidic (pH 6.1 +/- 1.2) and had the least volume (0.09 +/- 0.06 mL/kg). Group L-L was comparable with Group P-R in both pH and volume, whereas Groups P-L and O-O were similar to Group P-R only in volume. The proportion of patients at risk according to the traditional criteria (pH < 2.5 and volume 0.4 mL/kg) was significantly lower in Groups L-L (0%), P-L (4%), O-O (4%), and P-R (0%) than in Group P-P (48%) (P < 0.05). We concluded that two consecutive doses of lansoprazole or a morning dose of ranitidine seemed to be the most effective preanesthetic medication for reducing gastric acidity and volume.
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PMID:A comparison of lansoprazole, omeprazole, and ranitidine for reducing preoperative gastric secretion in adult patients undergoing elective surgery. 861 6

This study was designed to assess the efficacy of oral transmucosal fentanyl citrate (OTFC) for premedication in an adult population and to determine its effects on anxiety, sedation, gastric volume, and gastric fluid acidity. The fentanyl citrate is incorporated in a lozenge mounted on a handle (oralet). The effects of OTFC, placebo oralet, and no premedication were compared in a prospective, double-blind study on 90 adult ASA physical status I and II patients undergoing same-day admission surgery. Patients were randomly assigned to one of three groups: OTFC group (n = 30), placebo group (n = 30), and control group (n = 30). Arterial blood pressure, heart rate, respiratory frequency, and oxygen saturation determined by pulse oximetry were recorded before any premedication was given, and then every 10 min until the patient was taken to the operating room. Baseline anxiety and sedation levels were assessed to ensure group similarity immediately before premedication was given and at the more anxiety-provoking phase upon entering the operating room. Anxiety levels were rated using the Spielberger State-Trait Anxiety Inventory short form and sedation levels were assessed with the Ramsay scale. Side effects, as reported by the patients, were also recorded. Gastric contents were aspirated via an orogastric tube after induction of anesthesia and were measured for volume and pH. No significant differences were found among the three groups in mean arterial pressure, heart rate, or respiratory frequency. Initial oxygen saturation levels in all groups decreased after 30 min but not less than 96% except for one patient in the OTFC group, who decreased to 88%. On entering the operating room, the OTFC group demonstrated significantly higher levels of anxiolysis than the control group, but no significant differences were seen between the OTFC and the placebo groups or the placebo and control groups. Mean gastric volumes (OTFC, 29 mL; placebo, 26 mL; control, 24 mL) and pH (OTFC, 2.0; placebo, 1.8; control, 2.1) were similar in all groups. There were no significant differences among the groups in levels of sedation achieved. Mild dizziness or light-headedness was the most commonly reported side effect in 23% of the OTFC group. In the OTFC group, 71.4% like the premedicant effect as compared to 46.4% of the placebo group. Most of the groups found the oralet method of premedicant delivery very acceptable. This study demonstrates that the OTFC oralet is an effective anxiolytic in adults. It has minimal side effects and is prepared in an acceptable format. There was no measurable increase in gastric contents or acidity in the oralet groups, compared to those patients who were given nothing by mouth.
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PMID:Oral transmucosal fentanyl citrate for premedication in adults. 871 94

The concept that fasting produces an "empty stomach" has been shown to be incorrect. Numerous studies demonstrate that fasting neither diminishes gastric volume nor decreases gastric acidity and the risk of pulmonary aspiration is not increased by the preoperative intake of clear liquids. Nevertheless, most surgeons and anesthesiologists continue to adhere to the traditional NPO after midnight tradition, a tradition which should be abandoned. Withholding fluids preoperatively is not only of no benefit to patients but may even be harmful. Based on current knowledge and experience, the following guidelines, which represent a beneficial and humane advance for all surgical patients, are recommended. 1) Adults and children undergoing elective surgery under general anesthesia as inpatients or outpatients in good health (ASA Class I or II) and without specific contra-indications (such as morbid obesity, gastrointestinal disease, etc.) should be allowed and encouraged to drink clear fluids up to two hours before surgery. 2) Patients undergoing elective surgery under general anesthesia and major regional blocks that might require conversion to general anesthesia should remain NPO for solids and non-clear liquids for a minimum of six hours before scheduled surgery. 3) Patients undergoing elective surgery under regional local anesthesia in good health and without specific contra-indication should be allowed and encouraged to have their normal breakfast and fluids as desired on the day of surgery.
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PMID:"Nulla per os [NPO] after midnight" reassessed. 880 5

We conducted a two-part controlled study to evaluate the efficacy of preoperative oral pirenzepine (muscarinic receptor antagonist known to inhibit gastric secretion), ranitidine, and the combination pirenzepine-ranitidine in controlling gastric fluid pH and volume in 210 ASA I children, aged 2-14 yr, undergoing elective surgery. In the first part of the study (n = 90), the proportion of children considered at risk for aspiration pneumonitis was reduced with pirenzepine 25 mg (P < 0.05) but not with 12.5 mg. In the second part of the study, the other 120 children were allocated randomly to one of four groups: pirenzepine 25 mg with placebo; ranitidine 75 mg with placebo; pirenzepine 25 mg with ranitidine 75 mg; and placebo and placebo. These medications were administered 1 h before anaesthesia. After tracheal intubation, volume and pH of the gastric fluid aspiration via a multiorifice orogastric tube were measured. Pirenzepine 25 mg decreased gastric fluid volume (P < 0.05) but failed to increase gastric pH. Ranitidine 75 mg increased gastric pH (P < 0.05) but failed to decrease fluid volume. The pirenzepine-ranitidine combination reduced gastric fluid acidity and volume (P < 0.05).
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PMID:Comparison of pirenzepine, ranitidine, and pirenzepine-ranitidine combination for reducing preoperative gastric fluid acidity and volume in children. 950 78


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