The effect of motor activity following diagnostic lumbar puncture on the degree of post-puncture headache

An epidural catheter may be inserted with the patient either in the flexed left lateral or the sitting position. We have studied, non-invasively, the haemodynamic changes associated with these positions, using the thoracic bio-impedance method (BOMED NCCOM3 Monitor). Maternal arterial pressure and fetal heart rate were monitored simultaneously.Twenty healthy pregnant patients at term and 20 non-pregnant healthy controls, matched for age and height, were studied. The pregnant patients were scheduled for elective caesarean section and had singleton healthy fetuses. A significant reduction in stroke index (SI) occurred when the pregnant patients were repositioned from supine 15° wedged position to either flexed left lateral (P < 0.01) or sitting positions (P < 0.05). Similar reductions in SI with positioning were observed in the non-pregnant patients: flexed left lateral (P < 0.01); and sitting (P < 0.01). These changes in SI produced significant reductions in cardiac index (CI) in both groups. In the pregnant patients the CI was significantly lower in the flexed left lateral than in the sitting position (P < 0.01). Consequently maternal systolic blood pressure was lower in the flexed left lateral position (P < 0.01).