A survey of obstetrical anaesthesia practice,teaching and research in canadian university departments of anaesthesia

A report is presented of a questionnaire survey of obstetrical anaesthesia practice patterns, academic structure, resident teaching and research programmes in Canadian University Departments of Anaesthesia. Replies were received from 13 of the 16 departments, representing 24 university-affiliated hospitals. It is apparent that the majority of these hospitals do not have adequate obstetrical anaesthesia coverage. In most instances the delivery suite is covered by the anaesthetists on duty in the operating rooms. While epidural analgesia is widely used during labour, there are some hospitals where it still has a limited use, or is not used at all. Caesarean sections are still largely done under general anaesthesia in most reporting hospitals, with a few institutions reporting an increasing use of regional (mainly epidural) anaesthesia. Resident training in this branch of anaesthesia is felt to be deficient, based on the reports from many hospitals that resident staff are frequently not in attendance at deliveries; and on the evident failure in the majority of institutions to utilize their clinical material for teaching purposes. Research programmes in obstetrical anaesthesia are rare. The most common reason cited was the difficulty experienced in obtaining research funds. It is suggested that the major problems in obstetrical anaesthesia service, teaching and research are:

1. Economic,
2. Lack of interest, and
3. Lack of manpower.

It is recommended that consideration be given to:

1. Consolidation of obstetrical services into larger units wherever practical.
2. Creation of more geographic full time appointments in obstetrical anaesthesia.
3. More efficient use of clinical material for teaching.
4. Development in individual hospitals of prenatal and public education programmes.

     

Comparison of the 25-gauge Whitacre with the 24-gauge Sprotte spinal needle for elective Caesarean section: cost implications

Spinal anaesthesia provides rapid, safe anaesthesia for Caesarean section. The pencil-point spinal needles (Sprotte and Whitacre) are reported to have a low incidence of post-dural puncture headache (PDPH). As the 25G Whitacre is less expensive than the 24G Sprotte needle, this prospective, randomized, doubleblind study was designed to compare the incidence of PDPH and ease of insertion of these needles in 304 ASA 1 and 2 women having elective Caesarean section under spinal anaesthesia. Each patient was assessed daily for five consecutive days following Caesarean section by an investigator blinded to the needle used. The results indicate that the two needles have a similar ease of insertion, number of failed insertions, and failed subarachnoid blockade. An inability to insert the spinal needles occurred in two patients in each group. Therefore, 150 patients in each group completed the study. The incidence of PDPH with the 24G Sprotte needle was 4.0% (6/150) compared with 0.66% (1/150) with the 25G Whitacre (NS). There was no correlation between the occurrence of PDPH and the difficulty of needle insertion, presence of transient hypotension or the effectiveness of anaesthesia delivered. This study indicates that both needles are comparable with respect to ease of insertion and incidence of PDPH. As the Whitacre needle is less expensive it is a reasonable alternative to the more expensive Sprotte needle.     

Metoclopramide pharmacokinetics in pregnant and nonpregnant sheep

The pharmacokinetics of metoclopramide was studied in chronically instrumented pregnant and nonpregnant sheep. Metoclopramide was administered to the ewe by intravenous bolus injections (on a crossover basis) of 10, 20, and 40 mg, with an additional 80-mg dose to the nonpregnant animals. Transfer of the drug to the fetus was rapid with significant concentrations in fetal plasma 1 min after maternal dosing. The ratio of fetal-to-maternal area under the plasma concentration-time curves averaged 0.74, indicating significant fetal exposure to the drug. Maternal metoclopramide administration resulted in minimal fetal effects, with no change in arterial pressure, heart rate, or arterial pH or PCO2, and only a small (approximately 1.8 mmHg) transient decline in PO2. Plasma concentrations in maternal and fetal plasma in most animals were best described by a biexponential equation with rapid distribution and elimination phases. The terminal elimination half-lives in maternal and fetal plasma averaged 71.3 and 86.8 min, respectively, with fetal half-life being significantly longer. The number of fetuses present had no consistent effects on either maternal or fetal pharmacokinetic parameters. Total body clearance and volume of distribution averaged 3.5 L/h/kg and 5.8 L/kg, respectively, in the pregnant ewe, and 4.5 L/h/kg and 6.9 L/kg, respectively, in the nonpregnant animals. The terminal elimination half-life in the nonpregnant ewes averaged 67.5 min. Pharmacokinetic parameters were compared in the pregnant and nonpregnant ewes at the 10-, 20-, and 40-mg doses, and no significant differences were observed in the distribution or elimination rate constants, elimination half-life, or volume of distribution.(ABSTRACT TRUNCATED AT 250 WORDS)     

Linearity of metoclopramide kinetics at doses of 5-20 mg.

The disposition of metoclopramide was studied on a four-way crossover basis in six healthy non-smoking volunteers. The linearity of kinetic parameters and absolute bioavailability of metoclopramide were examined. In contrast to previous reports, metoclopramide obeyed linear kinetics over oral doses ranging from 5 to 20 mg. The absolute bioavailability of metoclopramide was 0.76 +/- 0.38 (mean +/- s.d.) from the oral dosage forms examined in this study.     

Effect of pH-adjustment of bupivacaine on onset and duration of epidural analgesia in parturients

Previous studies have reported that elevation of the pH of local anaesthetics is associated with enhanced quality and duration of block. This study investigated the effect, on time to onset and duration of analgesia, of pH adjustment of 0.25 per cent bupivacaine immediately prior to injection into the epidural space in parturients. Addition of 0.1 ml of 8.4 per cent sodium bicarbonate to 20 ml of 0.25 per cent bupivacaine consistently raised the pH of the local anaesthetic from 5.65 to 7.26 (mean values). Thirty parturients received an epidural injection of 8 ml of pH-adjusted 0.25 per cent bupivacaine and a control group of 30 parturients received 8 ml of the standard commercial preparation of 0.25 per cent bupivacaine. Elevation of the pH of the local anaesthetic significantly increased the speed of onset of analgesia from 6.0 minutes to 3.2 minutes and the duration of analgesia was significantly lengthened from 79.4 minutes to 96.5 minutes. There was no significant influence on time to peak effect, nor on mean maternal plasma levels of bupivacaine.     

Patient-controlled analgesia following caesarean section under general anaesthesia: a comparison of fentanyl with morphine

This prospective, randomised, double-blind study compared PCA fentanyl with PCA morphine for post-Caesarean section analgesia. Following a standardised general anaesthetic, 37 women were allocated to receive either fentanyl (n = 18) or morphine (n = 19). The PCA was commenced after the women had been made comfortable in the postanaesthetic recovery room with the appropriate opioid solution (mean dose required = fentanyl 375 μg or morphine 16 mg). Initial PCA settings were bolus 1 ml (fentanyl 25 μg or morphine 1 mg), lockout time ten minutes, and no background infusion. Both analgesic solutions provided effective analgesia for a mean of 37 hr with high levels of patient satisfaction, and there were no differences in VAS scores for pain and patient satisfaction, or for side effects (nausea, itch, and sleepiness) between fentanyl or morphine. However, more patients in the fentanyl group required supplementary boluses or alterations to the PCA settings (13/18 vs 4/19: P = 0.005), and one patient was removed from the study due to inadequate analgesia. We conclude that fentanyl is not recommended for routine PCA use following Caesarean section. Cette étude randomisée et à double aveugle compare la PCA au fentanyl avec la PCA à la morphine pour l’analgésie postcésarienne. Après une anesthésie générate standard, 37 femmes sont réparties pour recevoir soil du fentanyl (n = 18) soil de la morphine (n = 19). La PCA est debutée à la salle de réveil des que les patientes se sentent confortables sous une solution appropriée de morphinique (dose moyenne requise, fentanyl 375 μg ou morphine 16 mg). Le régime initial consiste en un bolus d’un ml (fentanyl 25 μg ou morphine 1 mg), un intervalle de sécurité de dix minutes, sans perfusion continue. Les deux solutions produisent une analgésie satisfaisante pour 37 h en moyenne avec un degré élevé de satisfaction pour la patiente, et on ne note pas de différence entre le fentanyl et la morphine pour l’évaluation de la douleur par EVA, le degré de satisfaction, et pour les effets secondaires (nausée, prurit et somnolence). Cependant, plus de patientes sous fentanyl ont eu besoin de bolus supplémentaires ou des modifications aux réglages de la PCA (13/18 vs 4/19; P = 0,005). Une patiente est exclue de l’étude pour raison d’insuffisance d’analgésie. En conclusion, nous ne recommandons pas la PCA au fentanyl après la césarienne.

---

Presented at the 1992 meeting of the Society for Obstetric Anesthesia and Perinatology (SOAP) in Charleston, South Carolina, USA.     

The effect of pH adjustment of bupi-vacaine on onset and duration of epidural anaesthesia for Caesarean section

Previous studies have reported that elevation of the pH of local anaesthetics results in more rapid onset of action, with enhanced quality and duration of block. This study investigated the effect of pH adjustment of 0.5 per cent bupivacaine immediately prior to epidural anaesthesia for Caesarean section. Addition of 0.1 ml of 8.4 per cent sodium bicarbonate to 20 ml of 0.5 per cent bupivacaine consistently raised the pH of the local anaesthetic from 5.49 to 7.04 (mean values). One hundred patients, presenting for elective Caesarean section under epidural anaesthesia participated in the study. Forty patients received epidural anaesthesia, using pH-adjusted 0.5 per cent bupivacaine, in a dosage adequate to produce block to the T4 level. A control group of 40 patients received the standard commercial preparation of 0.5 per cent bupivacaine. A further ten patients in each group received epidural anaesthesia using 0.5 per cent bupivacaine with the addition of 1:400,000 epinephrine, to study the effect of epinephrine on pH adjustment of the local anaesthetic. Elevation of the pH of the local anaesthetic significantly increased the speed of onset of action from 6.4 minutes to 3.2 minutes and the time to peak effect from 24.8 minutes to 18.1 minutes, while the duration of anaesthesia was increased from 124.8 minutes to 147.3 minutes. The time to S2 segment blockade was also shortened from 13.5 to 8.6 minutes. Addition of 1:400,000 epinephrine to the local anaesthetic did not influence the effect of pH adjustment. Maternal and umbilical cord plasma levels of bupivacaine were not affected by pH adjustment of the local anaesthetic, while MV/UV and UA/UV ratios were unaltered.     

A comparative study of patient controlled epidural analgesia (PCEA) and continuous infusion epidural analgesia (CIEA) during labour

In a randomised, single-blinded, placebo-controlled study, 27 parturients in labour receiving epidural 0.125 per cent bupivacaine, were assessed to evaluate the efficacy of patientcontrolled epidural analgesia (PCEA) compared with continuous infusion epidural analgesia (CIEA). Group A (n = 14) received a background infusion of 4ml hr^-1 0.125 per cent bupivacaine, with further 4 ml aliquots, self-administered, as required (up to 16 mi.hr^-1). Group B (n = 11) received a continuous infusion of 12 ml.hr^-1 through the same PCA apparatus, but with the demand-button deactivated. Both groups were similar in respect to age, height, weight, duration and outcome of labour, birthweight and neonatal Apgar scores. Patients in Group A (PCEA) received significantly less local anaesthetic than those in Group B (112 vs 15,2 mg.hr^-1). Pain relief was similar in both groups. Patients expressed overall satisfaction with PCEA, appreciating control over their own pain relief and less reliance on medical staff. PCEA is a safe, effective means of providing optimal analgesia during labour, with minimal local anaesthetic requirement.