Comparative Study Of Lumbar Epidural Pressure In Full Term Pregnant Women And Non-pregnant Women

Objective: To study the lumbar epidural pressure in full term pregnant women and non-pregnant women in the lateral position and the supine position respectively, and the change of the epidural pressure after injection of local anesthetics.Methods: Twenty American Society of Anesthesiologists (ASA) physical statusⅠorⅡfull term pregnant women (Group P) and fifteen non-pregnant women (Group NP) were given combined spinal-epidural anesthesia (CSEA) at L2-3 intervertebral space. Measure the instantaneous pressure when Tuohy needle was advanced into the epidural space (T0), the pressure 30 seconds (T1), 60 seconds (T2), 90 seconds (T3) after that, and the pressure 30 seconds (T4), 60 seconds (T5), 90 seconds (T6) after the patients were in the supine position, and the pressure 30 seconds (T7), 60 seconds (T8) and 90 seconds (T9) after 5 ml of 2% lidocaine was injected into the epidural space respectively.Results: All epidural pressures were positive from T0 to T9. The pressures in full term pregnant women were (17.1±9.0) mmHg,(14.9±4.7) mmHg,(14.0±2.3) mmHg,(14.1±2.1) mmHg,(27.4±5.4) mmHg,(23.4±4.6) mmHg,(21.3±4.0) mmHg,(27.7±6.9) mmHg,(23.3±4.4) mmHg,(21.2±3.4) mmHg respectively; and in non-pregnant women were (15.0±12.0) mmHg,(11.3±6.3) mmHg,(11.1±4.8) mmHg,(11.1±4.6) mmHg,(24.7±9.7) mmHg,(18.6±6.1) mmHg,(17.0±5.3) mmHg,(24.6±6.2) mmHg,(19.2±5.8) mmHg,(17.3±5.7) mmHg respectively. There were significant differences in epidural pressure at T2, T3, T5, T6, T8, T9 between the two groups, the epidural pressure in P Group was greater than NP group. There were significant differences in epidural pressure at T6 and T7 in each group, and no significant differences at T6, T8 and T9.Conclusion: The epidural pressures were positive in both full term pregnant women and non-pregnant women in the lateral and the supine position, not negative as traditional view. The epidural pressures were greater than the non-pregnant women both in the lateral and the supine position. The increase of the epidural pressure in the supine position lasted no more than 90 seconds after injection of 5 ml of 2% lidocaine at the rate of 0.5 ml/s through the catheter.