Farkhanda J. Husain

Systemic and pulmonary blood pressure during caesarean section in parturients with gestational hypertension.

Twenty severely pre-eclamptic patients requiring caesarean section for delivery were allocated to two groups. One group received epidural anaesthesia consisting of either 20 ml of bupivacaine 0.75 per cent at L3-4 or 12ml at Ll-2. The other group received general anaesthesia consisting of thiopentone, 40 per cent nitrous oxide and halothane 0.5 per cent. Mean arterial pressure (MAP), pulmonary artery pressure (PAP), pulmonary wedge pressure (PWP), and central venous pressure (CVP) were recorded at five-minute intervals for at least 60 minutes before operation and at least every two minutes during anaesthesia. Patients receiving general anaesthesia had pressures recorded every minute during tracheal intubation and extubation. There was a mean increase of MAP of 45 mm Hg, of PAP 20 mm Hg, and PWP 20mm Hg during intubation and extubation. Apart from a slight mean fall in MAP the parturients receiving epidural anaesthesia showed little change in these cardiovascular parameters.It is concluded that tracheal intubation of patients with gestational hypertension produces an increase in MAP, PAP, and PWP which can lead to a significant risk of cerebral haemorrhage and pulmonary oedema. The value and dangers of using short-acting hypotensive agents to prevent these episodes of hypertension has still to be assessed. With epidural anaesthesia there is a danger of hypotension which can be treated with intravenous fluid replacement and ephedrine.RésuméVingt patients en pré-éclampsie grave ont été divisées au hasard en deux groupes avant ľaccouchement par césarienne. Celles du premier groupe ont été opérées sous péridurale (20 ml de bupivacaïne à 0.75 pour cent injectés à L3 L4 ou 12 ml du même agent à L1, L2). Une anesthésie générale (thiopental, protoxyde ďazote à 40 pour cent et halothane à 0.5 pour cent) a été administrée aux patients du second groupe. La pression artérielle moyenne, la pression de ľartère pulmonaire, la pression capillaire bloquée et la pression veineuse centrale, ont été enregistrées aux cinq minutes durant au moins une heure avant ľintervention et au moins aux deux minutes durant ľanesthésie. On a effectué les mesures aux minutes au cours de ľintubation et de ľextubation chez les patientes soumises à une anesthésie générale. Au cours de ľintubation et de ľextubation, on a observé des élévations moyennes de 5.99 kPa (45 mm Hg) de la pression systémique moyenne et de 2.66 kPa (20 mm Hg) dans les cas de la pression de ľartère pulmonaire et de la pression capillaire bloquée. On n’a observé qu’une légère diminution de la pression systémique moyenne chez les patientes opérées sous péridurale.Donc, on retiendra que ľintubation trachéale chez les malades présentant une hypertension gravidique produit une élévation des pressions systémiques moyenne, pulmonaires et capillaires, avec un risque significatif ďhémorragie cérébrale et ďœdème aigu du poumon. Les avantages et les dangers liés à ľusage ďhypotenseurs ďaction courte restent à évaleur chez ces malades. Un dangerďhypotension existe avec ľanesthésie péridurale, hypotension qui se traite avec une charge liquidienne et ľéphédrine.

Obesity, gravity, and spread of epidural anesthesia.

Epidural anesthesia was administered for cesarean section in 250 parturients using 20 ml of 0.75% bupivacaine administered at L3–4 with the patient in a sitting position for 5 minutes. Comparing the results with those obtained in a previous study in which parturients were kept horizontal at all times, it was found that the sitting position limited cephalad spread of anesthesia only in obese patients and that the decrease in spread was in proportion to the degree of obesity. The previous findings that cephalad spread is positively correlated to body mass index BMI (weight in kilograms divided by height in meters squared) and with body weight were confirmed.

Incidence of venous air embolism during cesarean section is unchanged by the use of a 5 to 10 degree head-up tilt.

One hundred healthy parturients were divided at random into two demographically similar groups and were positioned for cesarean section either horizontally or flexed 5 to 10 degrees head up, with a 15 degrees lateral tilt. A Doppler ultrasound transducer was positioned over the fourth intercostal space parasternally. Initially, two patients received spinal, three general, and 95 epidural anesthesia. Two patients subsequently needed general for failed epidural anesthesia. Changes in Doppler heart tones (greater than 15 sec duration) indicative of venous air embolism (VAE) were identified 15 times in 11 patients--seven in supine and four in head-up patients (no statistically significant difference). Six awake patients (three horizontal, three head-up) developed chest tightness or pain during surgery, but only one episode correlated with VAE. No patient developed breathlessness. Moderate hypotension (greater than 10% decrease in systolic arterial pressure [SAP]) occurred in seven of 11 (63.6%) patients with, and in 26 (29.2%) of 89 patients without, VAE (P less than 0.001). More severe hypotension (SAP less than 90 mm Hg) due to bleeding occurred once. We conclude that a modest (5-10 degrees) head-up position does not influence the occurrence of VAE in patients having cesarean section. An 11% incidence of clinically insignificant VAE, although low, is still worrisome, as even small air bubbles in the circulation are potentially harmful, especially if the foramen ovale is patent. VAE during cesarean section should be anticipated and the anesthetic management planned accordingly.

Double-blind comparison of maternal analgesia and neonatal neurobehaviour following intravenous butorphanol and meperidine.

Butorphanol (1 mg and 2 mg) and meperidine (40 mg and 80 mg), given intravenously, were evaluated for analgesic efficacy and safety in a double-blind randomized study employing 200 consenting pre-partum patients in moderate to severe pain during the late first stage of labour. Both drugs provided adequate relief of pain to the mothers. There was no significant difference in the rate of cervical dilation, the foetal heart rate, the Apgar score, pain relief or neonatal neurobehavioural scores between those receiving butorphanol and those receiving meperidine. Twenty-two mothers who received butorphanol and eleven who received meperidine nursed their infants with no adverse effects observed. Side-effects were generally infrequent in this study; however, more side-effects were reported by the patients and observed by the investigator in the meperidine-treated cases (13%) than in the cases treated with butorphanol (2%).

A comparison of catheter vs needle injection of local anesthetic for induction of epidural anesthesia for cesarean section

It is generally believed that bolus injections of local anesthetic through an epidural needle produce a more rapid onset of blockade, but at the expense of an increased incidence and severity of hypotension, whereas intermittent injections through a catheter take longer to achieve adequate anesthesia but with a lower risk of hypotension. The present study investigated two commonly used needle and catheter epidural injection techniques for differences in speed of onset of surgical anesthesia and incidence and severity of hypotension. Term parturients scheduled for elective cesarean section were randomized into two groups to receive epidural anesthesia with intermittent injection either through the epidural needle (n = 44) or via a previously placed catheter (n = 44). The incidence and severity of hypotension was similar in the two groups. No significant difference was found for the time to onset of surgical anesthesia. In the absence of benefits of needle injection, incremental catheter administration of local anesthetic with its multiple safety advantages is the technique of choice for induction of epidural anesthesia for cesarean section.