Obstetric anaesthesia

From Ganfyd

Obstetric anaesthesia is generally considered to be one of the higher risk areas of anaesthetics for several reasons:

• Physiological changes of pregnancy increase some anaesthetic risks and introduce new areas of concern.
• The added complexity of considering the effect on the foetus of any anaesthetic plans or side effects.
• The nature of obstetric practice in having potentially disastrous complications of common procedures, such as Caesarean section or Instrumental delivery.

Suitable strategies for obstetric anaesthesia

General anaesthesia

Although in the past, a GA has been the most commonly used form of anaesthesia for Caesarian section, experience and self-observation as well as a better understanding of the Physiological changes of pregnancy has steered current anaesthetic practice away from using it as a default anaesthetic. The reasons for this are:

1. Anaesthetic mortality audits have consistently shown a higher perioperative death rate in women having a GA while in advanced pregnancy.
2. Physiological airway changes result in an increase in the failed intubation rate, which has been estimated as high as 1:300 attempts in pregnant women at term.
3. The increase in reflux symptoms in pregnancy and relative gastric stasis translates into higher rates of aspiration peri-operatively.
4. The increased cardiac output and oxygen demand of carrying a fetus results in a greatly reduced hypoxic reserve, making it much more difficult for the anaesthetist to get the patient out of difficulty, should an airway event occur.

Techniques for giving a GA in late pregnancy have been developed to address and mitigate these factors (and others) in order to give the patient the best chance, should they prefer a GA or be unsuitable for a regional technique.

Spinal anaesthesia

Established as a default anaesthetic in elective Caesarean sections, due to the many advantages to the patient and anaesthetist, notwithstanding the excellent safety and reliability of the technique.

Epidural anaesthesia

Combined Spinal / Epidural anaesthetic

A combined spinal and epidural (CSE) anaesthetic can be an extremely useful type of anaesthetic for most of the repeat Caesarean sections or in situations where surgical time is unpredictable. It is also useful as a means of providing rapid analgesia in labour in advanced first stage. Here is one method for a combined spinal-epidural anaesthetic.