The larger uterus encroaches to a greater degree upon the functional residual capacity, increasing hypoxaemia in the supine position. An unfavourable shift in the angle of the lower oesophageal sphincter increases the likelihood of regurgitation of gastric contents. The resulting risk of aspiration pneumonitis is compounded by a reduction in gastric pH induced by elevated gastrin levels. There is an increased incidence of postoperative vomiting. Regional anaesthetic techniques include epidural and subarachnoid blockade.
Aortocaval compression is more pronounced in multiple pregnancies.
In addition unpredictability in the spread of solution has been described. The unpredictability of response is a limitation of a single shot subarachnoid technique. The benefits of neuraxial opioids have not been specifically studied in this population. The fetus of multiple gestations. James FM Anesthetic Considerations for Breech or Twin Delivery.