Cerebrospinal fluid pressures during labor

Cerebrospinal fluid pressures were recorded throughout the course of labor in 10 normal parturients and one primigravida with pre-eclampsia. Measurements were made with the patients in the right lateral recumbent and in the supine positions. Bearing down efforts were evaluated during and between myometrial contractions. The influence of various methods of anesthesia on cerebrospinal fluid pressure was studied. In the normal parturient, resting cerebrospinal fluid pressures are within normal limits in the lateral recumbent and in the supine positions; in the pre-eclamptic parturient, the pressure is equally elevated in both postures. Increases in cerebrospinal fluid pressure during myometrial contractions are not related to contracting uterine musculature per se, but to movements of skeletal muscles occurring in response to the pain of myometrial contraction. Therefore, rises in cerebrospinal fluid pressure during uterine contraction may be prevented by any means affording abolition of pain perception. This may be light third-stage inhalation anesthesia or regional block anesthesia above a sensory level of T12. However, most of the commonly used inhalation agents lead to elevations in the cerebrospinal fluid pressure base line. Regional block techniques, on the other hand, do not alter cerebrospinal fluid pressure. The problem of additional cerebrospinal fluid pressure increases during uterine contractions and during inhalation anesthesia are discussed with regard to the patient with pathologically elevated cerebrospinal fluid pressure.