magnesium-trisilicate and Pneumonia--Aspiration

Topics: Anesthesia, Obstetrical; Cesarean Section; Citrates; Citric Acid; Clinical Trials as Topic; Female; Humans; Magnesium; Magnesium Silicates; Pneumonia, Aspiration; Postoperative Complications; Preanesthetic Medication; Pregnancy; Silicic Acid; Silicon Dioxide

Eighty women (40 for elective Caesarean section and 40 for elective gynaecological surgery) were randomly assigned to one of five treatment groups and received pre-operatively either no medication; magnesium trisilicate mixture (BP) 30 ml; metoclopramide 10 mg intramuscularly; ranitidine 150 mg orally on the night prior to, and the morning of, surgery; or metoclopramide 10 mg intramuscularly in combination with oral ranitidine 150 mg (the latter again given on the night prior, and the morning, of surgery). The effect of these medications on intragastric pH, volume and serum gastrin-17 was measured. No patient receiving ranitidine had a pH of less than 4. Magnesium trisilicate mixture resulted in the largest intragastric pH change although one woman in this group had a pH of 1.7. The largest intragastric volumes were seen in the patients who had received magnesium trisilicate mixture, whilst the patients who had received metoclopramide in combination with ranitidine had the smallest intragastric volumes. Magnesium trisilicate mixture and metoclopramide resulted in no change in serum gastrin levels. However, in the subjects who had received ranitidine on the night prior to surgery, the fasting serum gastrin was significantly higher (p less than 0.01) than the values in the remaining subjects, the mean (SEM) values being 60.3 (6.3) pg/ml in those not receiving ranitidine and 111.3 (19.5) pg/ml in those who had been given ranitidine.

Topics: Adult; Antacids; Drug Therapy, Combination; Female; Gastrins; Humans; Hydrogen-Ion Concentration; Magnesium; Magnesium Silicates; Metoclopramide; Pneumonia, Aspiration; Pregnancy; Premedication; Ranitidine; Silicic Acid; Silicon Dioxide; Stomach

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.

Topics: Anesthesia, Obstetrical; Antacids; Cimetidine; Citrates; Citric Acid; Emergencies; Female; Humans; Hydrogen-Ion Concentration; Magnesium; Magnesium Silicates; Pneumonia, Aspiration; Pregnancy; Pregnancy Complications; Premedication; Random Allocation; Silicic Acid; Silicon Dioxide; Stomach

The choice of drugs for acid aspiration prophylaxis in 288 obstetric anaesthetic departments in the United Kingdom was determined by questionnaire. The results are compared with a similar survey of anaesthetic departments 5 years ago. The prescription of sodium citrate and the H2 receptor antagonist ranitidine has superseded that of Mist. magnesium trisilicate.

Topics: Anesthesia, Obstetrical; Antacids; Cesarean Section; Citrates; Citric Acid; Female; Humans; Magnesium; Magnesium Silicates; Pneumonia, Aspiration; Postoperative Complications; Pregnancy; Ranitidine; Silicic Acid; United Kingdom

Inhalation of gastric contents remains an important cause of anaesthetic death. Recent data describe the acid aspiration syndrome (AAS) as the cause of 25% of maternal deaths associated with anaesthesia and 19% of all deaths totally attributable to anaesthesia (DHSS, 1982; Lunn and Mushin, 1982).

Topics: Administration, Oral; Analgesics, Opioid; Anesthesia; Anesthesia, Obstetrical; Cimetidine; Citrates; Citric Acid; Drug Therapy, Combination; Esophagogastric Junction; Food; Gastric Acid; Gastric Emptying; Gastroesophageal Reflux; Humans; Hydrogen-Ion Concentration; Magnesium; Magnesium Silicates; Metoclopramide; Pneumonia, Aspiration; Preoperative Care; Pressure; Ranitidine; Risk; Silicic Acid

Topics: Antacids; Cesarean Section; Female; Humans; Magnesium; Magnesium Silicates; Pneumonia, Aspiration; Postoperative Complications; Pregnancy; Silicic Acid; Silicon Dioxide

Study of samples of magnesium trisilicate mixture BP obtained commercially has shown that redistribution of the mixture into a reasonably well-dispersed suspension becomes increasingly difficult the longer the mixture is stored. This process of compacting is hastened in response to an increase of environmental temperature. It is possibly for this reason that to administer the mixture at some time later than shortly after it has been prepared contravenes the recommendation of the British National Formulary, that 'it should be recently prepared.' These findings were reflected in the contrast between gastric aspirates obtained from anaesthetised patients who had received the commercially-obtained antacids and those whose antacid had been prepared by the hospital pharmacy. There was a higher incidence of patients 'at risk' because of aspirates with pH value less than 3.0 in the former group. Among the latter group of 131 patients, only one was found to have been 'at risk'. The importance of administering a final dose of antacid within the 15-minute period before induction of anaesthesia is emphasised. The results of assays of the magnesium concentration in the gastric aspirates varied widely, and bore no systematic relationship to the total dose of antacid administered, the time elapsing since the last dose was given, or the pH value of the same aspirate.

Topics: Anesthesia, Obstetrical; Antacids; Drug Administration Schedule; Drug Stability; Drug Storage; Female; Humans; Hydrogen-Ion Concentration; Magnesium; Magnesium Silicates; Pneumonia, Aspiration; Pregnancy; Premedication; Silicic Acid; Silicon Dioxide; Stomach

Topics: Aluminum Hydroxide; Antacids; Humans; Magnesium; Magnesium Hydroxide; Magnesium Silicates; Pneumonia, Aspiration; Silicic Acid; Silicon Dioxide

Topics: Anesthesia, Obstetrical; Antacids; Cesarean Section; Cimetidine; Female; Guanidines; Humans; Magnesium; Magnesium Silicates; Pneumonia, Aspiration; Pregnancy; Silicic Acid

Three groups, each of forty children aged less than five years and prepared for elective surgery, had their gastric contents' volume and pH measured. The control group showed an incidence of 67-5 per cent with high acidity (pH equal to or less than 2-5). In the second and third groups magnesium trisilicate mixture was given within thirty minutes prior to induction of anaesthesia. The second group, sampled after induction of anaesthesia, showed a marked reduction in acidity, while the third group, sampled at the termination of anaesthesia and surgery, demonstrated that in most cases the neutralization of gastric acidity was still effective.

Topics: Anesthesia, General; Child, Preschool; Female; Gastric Acidity Determination; Humans; Hydrogen-Ion Concentration; Infant; Infant, Newborn; Magnesium; Magnesium Silicates; Male; Pneumonia, Aspiration; Preoperative Care; Silicic Acid; Silicon Dioxide