General anaesthesia in obstetrics

The following ought to be considered in anaesthetising a woman in labour:

• normotension, because of aorto-caval compression, may not actually be normal, and may be harmful to the fetus
• the size of the lungs are reduced in a term mother, and the oxygen requirements are higher
• acid aspiration is a common complication with the high pressures of labour, especially when combined with agent which delay gastric emptying (eg opiates)
• direct effects of drugs on the fetus can be avoided with a quick delivery, ie no time for transplacental diffusion
• anaesthesia is always a risk in labour; an emergency anaesthetic constitutes a high risk.
• most of the mortality and morbidity results from failure to intubate with subsequent hypoxia and aspiration.
• the anaesthetic must remove awareness!