A comparison of omeprazole and ranitidine for prophylaxis against aspiration pneumonitis in emergency Caesarean section

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.     

Comparison of the effects of famotidine and ranitidine on gastric secretion in patients undergoing elective surgery

A randomised double-blind comparison of oral famotidine and ranitidine given 2 hours before induction, on gastric secretion (volume and pH) was carried out on 93 patients undergoing elective surgery. Gastric contents were aspirated immediately after tracheal intubation. Famotidine significantly reduced the gastric volume, compared with the other groups, including ranitidine. Both famotidine and ranitidine significantly elevated gastric pH towards neutral, compared with the other groups. There was no significant difference between ranitidine and famotidine in respect of the pH. The patients premedicated with famotidine and ranitidine were well protected against Mendelson's syndrome, whereas 38% of patients from the other groups remained at risk.     

Ranitidine as an antacid before elective Caesarean section

In a preliminary study, 20 women in labour received ranitidine 50 mg intravenously. No significant changes were seen in the height, frequency or amplitude of uterine contractions or in fetal heart rate or pattern. No neonatal problems attributable to ranitidine were found. Ranitidine crossed the placenta, the mean fetal-maternal ratio being 0.9. Levels in the infants 12 hours following delivery were all very low. Ranitidine 150 mg orally was given to 80 healthy women undergoing elective Caesarean section at varying times from 75 to 510 minutes pre-operatively. From 2 to 6 hours following ingestion, the pH of gastric contents was greater than 2.5 in all but one patient. The mean volume aspirated (8 ml) was significantly lower than in a control group receiving magnesium trisilicate (mean volume 30 ml). Neonatal assessment included Apgar scoring, neurobehavioural examination, feeding progress, measurement of acidity and culture of gastric aspirates. No significant differences between groups were found. Blood levels indicated that the oral drug is readily absorbed by the parturient and that a smaller proportion is transferred to the fetus, mean fetal-maternal ratio at delivery being 0.38.     

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 effects of oral nizatidine and ranitidine on gastric volume and pH in patients undergoing gynaecological laparoscopy

Ninety patients who presented for elective gynaecological laparoscopy as day cases were allocated at random to three groups and studied on a double blind basis to compare the effects of nizatidine, ranitidine or placebo on gastric secretion. All the patients received the active drugs or placebo orally at least 45 minutes before the induction of anaesthesia. After tracheal intubation gastric fluid was aspirated via an orogastric tube and the volume and pH of the aspirate were measured. Venous blood samples were obtained at the times of gastric sampling to determine the plasma levels of the drugs. The proportion of patients with both pH greater than 2.5 and volume less than 25 ml were 100%, 90%, and 92.9% in the nizatidine, ranitidine and placebo groups respectively. There was no difference in volume between groups. Two patients in the nizatidine group without a measurable aspirate had blood levels less than the therapeutic range. The median pH values in both treated groups were significantly greater than in the placebo group, but there were no differences between the two treated groups. There were 19 (67.8%) patients in the placebo group with pH less than 2.5. This was significantly higher than the 2 (7.4%) and 6 (20%) in the nizatidine and ranitidine groups respectively. When the time interval between drug administration and induction of anaesthesia was divided arbitrarily into 45-90 minutes and greater than 90 minutes, all the patients in the nizatidine and ranitidine groups with pH less than 2.5 were given the drugs in the 45-90 minute interval; this suggests a latent period is required before the gastric pH increases. Nizatidine may be an effective protective agent against acid aspiration syndrome.     

Gastric emptying following Caesarean section and the effect of epidural fentanyl

The rate of absorption of paracetamol following oral administration was used as an indirect measure of the rate of gastric emptying. This was to determine the effect on gastric motility of the addition of fentanyl to a solution of local anaesthetic given into the epidural space to provide pain relief following Caesarean section. Thirty subjects were randomly allocated to receive either bupivacaine plus fentanyl or bupivacaine alone. The area under the curve of the graph of plasma paracetamol concentration versus time was calculated for each subject at 45 and 90 minutes after administration of the epidural injection, and this value was used as an index of the rate of gastric emptying. This study demonstrated that gastric emptying may be normal immediately following Caesarean section under epidural anaesthesia, but that if fentanyl is added to the epidural solution, gastric emptying is significantly slower in the first 45 minutes following surgery (p less than 0.05).     

Subarachnoid anaesthesia for elective Caesarean section

Forty patients who underwent elective lower segment Caesarean section under subarachnoid anaesthesia received either 2.0 ml 0.5% cinchocaine in 6% dextrose or 2.5 ml 0.5% bupivacaine in 8% dextrose via a 26-gauge needle with the patient in the left lateral position. Onset time was rapid in both groups and the distribution of maximum ascent of sensory analgesia was T1-T6. Efficacy of analgesia was greater in the bupivacaine group, although the duration of both sensory and motor blockade was shorter than following cinchocaine. There were no significant differences between the two groups either in the incidence and severity of complications or in the condition of the neonates. The high incidence (50-65%) and often profound extent of hypotension seen throughout the trial, confirm the ineffectiveness of crystalloid preload of 1500 ml as a single prophylaxis against hypotension.     

The use of antacids as a prophylaxis against Mendelson''s syndrome in the United Kingdom. A survey

Maternal mortality from aspiration of gastric contents still remains unacceptably high, despite various recommended prophylactic measures. In order to establish which forms of antacid prophylaxis are currently being used, a questionnaire was sent to anaesthetists working in obstetric units in the United Kingdom. Despite its limitations, magnesium trisilicate remains the most popular antacid during labour and before Caesarean section.     

Comparison of propofol and thiopentone for induction of anaesthesia for elective Caesarean section

Propofol 2.5 mg/kg was compared with thiopentone 5 mg/kg as an induction agent for elective Caesarean section. Thirty-two healthy women with cephalopelvic disproportion were included in an open randomised study. The placental transfer of propofol was also studied in 10 other mothers given a single dose of 2.5 mg/kg. The induction characteristics and haemodynamic response to propofol and thiopentone were similar. Side effects were rare with both agents, but propofol caused more discomfort on injection compared to thiopentone. Recovery times were shorter after propofol as evaluated by time to orientation, recovery scoring after anaesthesia and measurements with the Maddox wing. Rapid placental transfer and significant fetal uptake were detected for propofol. There was no significant neonatal depression as assessed by Apgar scores and blood gas analyses. Propofol appears to be a suitable alternative to thiopentone as an induction agent for anaesthesia in elective Caesarean section.     

Impact of spinal anaesthesia and obesity on maternal respiratory function during elective Caesarean section

Spinal anaesthesia for Caesarean section has gained widespread acceptance. We assessed the impact of spinal anaesthesia and body mass index (BMI) on spirometric performance. In this prospective study, we consecutively assessed 71 consenting parturients receiving spinal anaesthesia with hyperbaric bupivacaine and fentanyl for elective Caesarean section. We performed spirometry during the antepartum visit (baseline), immediately after spinal anaesthesia, 10-20 min, 1 h, 2 h after the operation, and after mobilisation (3 h). Baseline values were within normal ranges. There was a significant decrease in all spirometric parameters after effective spinal anaesthesia that persisted throughout the study period. The decrease in respiratory function was significantly greater in obese (BMI > 30 kg x m(-2)) than in normal-weight parturients (BMI < 25 kg x m(-2)), e.g. median (IQR) vital capacity directly after spinal anaesthesia; -24 (-16 to -31)% vs. -11 (-6 to -16)%, p < 0.001 and recovery was significantly slower. We conclude that both spinal anaesthesia and obesity significantly impair respiratory function in parturients.     

The effects of intrathecal diamorphine on gastric emptying after elective Caesarean section

This study investigated whether intrathecal diamorphine affects gastric emptying following elective Caesarean section. Forty women were randomly allocated to receive either diamorphine 300 microg or 0.9% saline as part of a standard spinal anaesthetic. Gastric emptying was measured in the immediate postoperative period using paracetamol absorption. Paracetamol concentrations were measured by enzymatic assay method using a Beckman CX-7 automated analyser. The time to maximum concentration (Tmax) was statistically longer in the diamorphine group (control 41.8, SD 20.8 min; diamorphine 72.6 SD 41.9 min; p < 0.01). During the 2-h study period, mean morphine consumption via a patient controlled analgesia device was significantly higher in the control group (control 9.3, SD 3.6 mg; diamorphine 2.1, SD 2.1 mg; p < 0.01). We conclude that intrathecal diamorphine may contribute to the delay in gastric emptying that occurs immediately following elective spinal Caesarean section.     

Glycopyrronium and hypotension following combined spinal-epidural anaesthesia for elective Caesarean section in women with relative bradycardia

The ability of glycopyrronium to reduce the severity of hypotension following subarachnoid block in parturients with a relative bradycardia was evaluated in a double-blind randomised controlled study. Women with a resting heart rate of < or = 80 beat x min(-1) presenting for elective Caesarean section were randomly allocated to receive either glycopyrronium 2 microg x kg(-1) or normal saline intravenously once positioned for combined spinal-epidural anaesthesia. Following spinal injection of 2.6 ml hyperbaric bupivacaine 0.5% and fentanyl 15 microg, women randomly allocated to the saline group were given 6 mg ephedrine so that all parturients received some prophylaxis against hypotension other than the fluid preload. Further ephedrine and fluid boluses were administered if mean arterial pressure fell 20% or more from resting values. Using a sequential analysis technique, analysis after the first 20 subjects indicated the study should be stopped, with no difference in ephedrine requirements or hypotension between the groups. We conclude that pretreatment with glycopyrronium 2 microg x kg(-1) is no more effective than 6 mg ephedrine in preventing hypotension following subarachnoid block in parturients with relatively low resting heart rates.     

Epidural versus general anaesthesia for elective Caesarean section Effect on Apgar score and acid-base status of the newborn

Elective Caesarean section deliveries over a 5-year period were studied to compare the effect of epidural block with general anaesthesia on the condition of the infant at birth. The Apgar score and umbilical arterial acid-base status were used as determinants of the latter. Epidural block was used in 139 (22.8%) mothers while 471 (77.2%) were performed under general anaesthesia. No babies in the epidural group were severely depressed (Apgar less than 4), compared with 6.2% in the general anaesthesia group. Only 4.3% of the epidural sections were moderately depressed (Apgar 4-6), compared with 15.4% of the others. These differences remained highly significant when infants of less than 2500 g were excluded, and when matched groups were compared. Mean umbilical arterial pH was similar within the two groups (pH 7.28), and was not consistent with asphyxia in almost 90% of the depressed infants. The findings suggest that general anaesthesia, rather than asphyxia or aortocaval compression, is responsible for most of the depressed infants born by elective Caesarean section. This may involve over 20% of babies delivered in this manner, so greater use of epidural block for elective Caesarean section is recommended. Further investigations are required to improve results with general anaesthesia.     

Some aspects of epidural block provided for elective Caesarean section

We present here clinical data from 993 patients who were destined to undergo elective Caesarean section under epidural analgesia. In 29 cases the attempt to provide an epidural was abandoned before the operation started. In regard to this, the importance of monitoring the fetal heart rate during initiation of the epidural is emphasised. In 10 cases general anaesthesia was induced after delivery, and in a further 108 cases supplemental analgesia was administered, either systemically, by inhalation or by an additional epidural top-up, after delivery. Satisfactory analgesia throughout the operation was achieved in 87.8%. In an appreciable proportion of cases the recommended maximum dose of bupivacaine, and the recommended maximum rate of bupivacaine administration, were exceeded without apparent complication. There was a tendency for the volume of Hartmann's solution infused intravenously before and during initiation of the epidural to be increased throughout the period under review (1971-85). The prevalence of hypotension diminished during that period. Characteristics of the data did not permit a close analysis of the main factors which could have led to an episode of maternal hypotension. However, it did appear that such an episode could be ascribed to too brief an interval between the first and second, or the second and third top-up doses. The frequency with which blood was transfused during operation was markedly lower than that noted in a concurrent series of elective sections conducted under general anaesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anaesthetic management of a quadriplegic patient with severe respiratory insufficiency undergoing Caesarean section

The anaesthetic management of a 30-year-old pregnant quadriplegic patient with severe respiratory insufficiency undergoing Caesarean section is described. Quadriplegia and respiratory insufficiency pose potential problems for anaesthetists and these are discussed. In particular autonomic hyperreflexia may occur and this may be mistaken for pre-eclampsia.     

Effect of single-dose omeprazole on intragastric acidity and volume during obstetric anaesthesia

Various antacid or antisecretory agents are used to reduce the risk to patients of aspiration of gastric contents during general anaesthesia and a trial of the gastric proton pump inhibitor, omeprazole, is reported here. Twenty women admitted for elective Caesarean section under general anaesthesia received a single 80-mg oral omeprazole dose at 2000 hours on the evening before surgery. Intragastric pH and volume were measured immediately after induction of anaesthesia and on completion of surgery. Eighty-five percent of pH measurements at induction and extubation and 80% and 95% of volume measurements at induction and extubation respectively met the defined success criteria (pH greater than or equal to 2.5, volume less than 25 ml). Omeprazole treatment was well tolerated by the women and Apgar scores and subsequent progress of the babies were acceptable. These results indicate that gastric acidity and volume were acceptable in the majority of women after omeprazole treatment, but the interval from drug administration to induction of anaesthesia may have been too long in some cases and resulted in unacceptably low pHs.     

Anaesthetic management of Caesarean section in an elderly parturient with pre-eclampsia

The number of women over 40 years of age becoming pregnant has increased over recent years. They suffer a high incidence of hypertensive complications, and require more frequent operative interventions. We present a case report of a 51-year-old woman having a Caesarean section for a twin pregnancy complicated by pre-eclampsia. We discuss the effects of age on pregnancy and the implications for anaesthetic management.