Epidural analgesia with left lateral tilt for Caesarean section

Abstract

The specific anaesthetic dangers to the mother during anaesthesia for Caesarean section include the aspiration of highly acidic stomach contents, l s Z and supine hypotensive synd r~m e .~.~ The main dangers to the baby are respiratory depression due to the transfer of anaesthetic and narcotic drugs and asphyxia due to maternal hypoxia and hypotension. No uniform pattern has yet emerged regarding the choice of anaesthesia for Caesarean section.Light general anaesthesia with thiopentone, nitrous-oxide, oxygen and muscle relaxants has the advantage of providing a stable cardiovascular system and a better control of oxyg e n a t i~n ,~ but the danger of aspiration to the mother still All general anaesthetics cross the placental barrier producing some degree of foetal depression. The incidence of unpleasant recall during this operation under light general anaesthesia is another drawback.There is less risk of aspiration of stomach contents or of metabolic disturbances with spinal or epidural analgesia than with any type of general anaesthetic technique, but the supine hypotensive syndrome may be exaggerated.The high incidence of hypotension has made these techniques unpopular with many anaesthetists.Post-spinal h e a d a~h e '~ may occur following thecal puncture but permanent neurological complications are now recognised to be very rare.15-17A number of studies have been carried out to evaluate means of preventing the so-called 'inevitable' hypotension during spinal and epidural analgesia. The suggested prophylactic measures include the use of small doses of local analgesic drugs, l 8 prevention of bradycardia by means of intravenous atropine, l 9 infusion of relatively large volumes of intravenous fluids,20 and the use of head down posture to improve venous return and cardiac output.12 Methods to release the pressure from gravid uterus on the inferior vena cava, iliac veins, and lower part of abdominal aorta include lateral uterine displacement (LUD) either manually or mechanically21*22 and the use of v a s o p r e s~o r s .~~ It was decided to keep these factors in mind in a study of a series of patients undergoing Caesarean section in whom a standard method of epidural analgesia was employed, using left lateral tilt in an effort to reduce the incidence of hypotension. Materials and methodsThe study was carried out in seventy-five healthy women scheduled for either elective or emergency Caesarean section. Patients with severe cardiovascular disease, hypovolaemia, local sepsis, cord prolapse or active bleeding were excluded from the study.All patients were prernedicated with intravenous atropine 0.6 mg just prior to the block. Epidural block was performed by a standard method using a Tuohyneedle in L2/3 interspace and the loss of resistance sign. Lignocaine 2% with 1 :200,000 adrenaline was used in all cases. The dose schedule is shown in Table 1.Various steps were taken to prevent hypotension and hypoxia. These were: atropine 0.6 mg i.v. just prior to the block; preloading of circulation with 0.9% saline 500-1000 ...

Obstetrics, Analgesia and Anaesthesia

“…The continued investigations into a variety of anaesthetic induction agents (Downing, Mahomedy et al, 1974;Holdcroft et al, 1974;Stovner and Vangen, 1974;Holdcroft et al, 1975) and into volatile agents used for the maintenance of anaesthesia (Coleman and Downing, 1975;Crawford and Davies, 1975;Crawford et al, 1976), although pursued with the intent of reducing the incidence of maternal "awareness" from about 4% to zero, and of eliminating entirely the currently extremely low incidence of drug-induced neonatal depression, are now beginning to assume some of the characteristics of academic exercises. The only foreseeable major advance in this area in the United Kingdom is the application on an increasing scale of extradural block for Caesarean section (Baheti et al, 1975). This practice is being pursued with increasing intensity in many centres, and according to all the reports received informally by the present writerincluding that of a study conducted in his own hospital-provided that the mother is appropriately "pre-loaded" with i.v.…”