Serial peak expiratory flow rates in mothers during caesarean section under extradural anaesthesia.

Peak expiratory flow rate (PEFR) was measured in 19 mothers during elective Caesarean section under unsupplemented extradural anaesthesia. In 18 mothers, serial measurements of peak expiratory flow rate indicated adequate expiratory reserve and residual abdominal muscle power consistent with an effective cough. In one mother, with severe respiratory disease, PEFR decreased to a value indicative of inadequate cough. Data for one other mother who came for emergency Caesarean section after 4 h of an extradural infusion also indicated an inability to cough.