The influence on foetal outcome of maternal Pco2 at caesarean section under general anaesthesia was assessed in 27 “clinically acceptable ideal patients” as defined by Crawford.1 A standard anaesthetic technique was employed which utilised left lateral tilt and an F1o2 of 0.5. A highly significant relationship (p < 0.001) was found between umbilical vein Po2 and maternal end-tidal Pco2 in the range 20-40 mmHg, such that hypocarbia was associated with a lowering of umbilical vein Po2. In spite of this relationship, only three values of Po2 were less than normal (28 mmHg). No relationship was found between clinically measured parameters of foetal outcome and maternal end-tidal Pco2. The relevant literature is reviewed.
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