One hundred and fifty "clinically acceptable ideal cases" undergoing elective Caesarean section under a standardized regimen of general anaesthesia were studied. In 87 cases the patient was supine throughout the procedure and in 63 cases she was tilted laterally by means of a wedge. Statistical analysis of the data derived from assays of maternal and cord blood, and of the Apgar-minus-colour scores indicated that: there was among the non-tilted patients a higher incidence, and greater degree, of birth asphyxia and of low A-C scores than in the tilt series, and that this disparity was emphasized by prolongation of the I-D interval; there was a greater variance among the results obtained from the non-tilt series, suggesting that the introduction of a tilt led to a more stable situation. It is suggested that the contrasts reflect the effect of caval occlusion by the gravid uterus, and the introduction of the terms "revealed caval occlusion" and "concealed caval occlusion" is advocated. Possibly, drug-induced depression was observed among infants who were delivered within 10 minutes of induction, but no other neonatal effects referable to the drugs used could be identified.

One hundred and fifty "clinically acceptable ideal cases" undergoing elective Caesarean section under a standardized regimen of general anaesthesia were studied. In 87 cases the patient was supine throughout the procedure and in 63 cases she was tilted laterally by means of a wedge. Statistical analysis of the data derived from assays of maternal and cord blood, and of the Apgar-minus-colour scores indicated that: there was among the non-tilted patients a higher incidence, and greater degree, of birth asphyxia and of low A-C scores than in the tilt series, and that this disparity was emphasized by prolongation of the I-D interval; there was a greater variance among the results obtained from the non-tilt series, suggesting that the introduction of a tilt led to a more stable situation. It is suggested that the contrasts reflect the effect of caval occlusion by the gravid uterus, and the introduction of the terms "revealed caval occlusion" and "concealed caval occlusion" is advocated. Possibly, drug-induced depression was observed among infants who were delivered within 10 minutes of induction, but no other neonatal effects referable to the drugs used could be identified.

A further study of general anaesthesia for Caesarean section. British Journal o/ Anaesthesia, 48, 661-667. 3. 4. CRAWFORD, J.S. (1965) Maternal and cord blood at delivery: vertex vaginal delivery of mature infant. Parameters of respiratory exchange. Biologia Neonatorurn, 8, I3 1-1 72.

One hundred and fifty "clinically acceptable ideal cases" undergoing elective Caesarean section under a standardized regimen of general anaesthesia were studied. In 87 cases the patient was supine throughout the procedure and in 63 cases she was tilted laterally by means of a wedge. Statistical analysis of the data derived from assays of maternal and cord blood, and of the Apgar-minus-colour scores indicated that: there was among the non-tilted patients a higher incidence, and greater degree, of birth asphyxia and of low A-C scores than in the tilt series, and that this disparity was emphasized by prolongation of the I-D interval; there was a greater variance among the results obtained from the non-tilt series, suggesting that the introduction of a tilt led to a more stable situation. It is suggested that the contrasts reflect the effect of caval occlusion by the gravid uterus, and the introduction of the terms "revealed caval occlusion" and "concealed caval occlusion" is advocated. Possibly, drug-induced depression was observed among infants who were delivered within 10 minutes of induction, but no other neonatal effects referable to the drugs used could be identified.