Assessment of autonomic nervous system in non-pregnant, pregnant and pre-eclampsia patients

During pregnancy, there are remarkable changes in the circulation. Blood pressure and vascular resistance are increased in woman with pre-eclampsia, the blood volume is smaller, and blood pressure and heart rate responses to various provocations are changed compared with those of normotensive pregnant women. Autonomic nervous system [ANS] functions were investigated in women subdivided into three groups [non-pregnant, pregnant, pre-eclampsia]. Cardiovagal arch functions was assisted by spontaneous heart rate and blood pressure variabilities, deep breathing test and valsalva maneuver. Evaluation of adrenergic vasomotor response to posture and Cold stress test [CST] and evaluation of Heart Rate Variability was done. All the tests were done at 30-38 weeks of gestation. There was high significant difference between normal pregnancy group and pre-eclampsia groups in heart rate [HR], systolic blood pressure [SBP] and diastolic blood pressure [DBP]. There was no significant difference between groups in oxygen [O[2]] saturation. As for skin temperature, there was significant decrease in pre-eclampsia reading than the pregnant group. As regard baroreflex function, there was an increase in heart rate with deep inspiration and decrease in heart rate with expiration with no statistical difference between groups as regard the mean heart rate for three groups [p>0.05]. However, the% of change of maximal heart rate response to deep breathing was diminished [17.93%] than non pregnant [48.7%] and the maximal heart rate response to deep breathing was diminished in cases of pre-eclampsia [3.65%] than normal group. The difference between groups was highly significant in lowest heart rate and blood pressure with valsalva maneuver. There was decrease in valsalva ratio in pregnant groups than in non pregnant group but the valsalva ratio was decreased in pre-eclampsia group more than normal pregnant group. The decrease in blood pressure during strain was more marked in normal groups than PIH group. There was increase in heart rate and systolic and diastolic blood pressure during cold stress test and decrease in O[2] saturation and skin temperature in all groups with significant difference between groups in HR, SBP, DBP and skin temp 20 minutes after CST [there was delayed recovery pre-eclampsia group]. As regard HR variability; increase in HR in pre-eclampsia than normal groups in pregnant and non-pregnant. There was increase in HR in the two pregnant groups with significant difference in pregnant than in non pregnant women [p<0.01]. There was reduced HR variability [NN, SD and rMSSD] during pregnancy than in non-pregnant women [p<0.01]. During pregnancy changes in the ANS occur. Normal pregnancy is associated with significant decrease in baroreflex gain as compared with non pregnant state and this decrease in baroreflex gain is even more pronounced in subjects with hypertensive disorders with pregnancy. ANS evaluation can predict abnormal changes in the circulatory system and therefore, early detection can be important to reduce or prevent hemodynamic instability during regional or general anesthesia. Impairment of autonomic nervous system functions may be the cause of pre-eclampsia