Vasopressor therapy for hypotension due to epidural anesthesia for cesarean section

Abstract

Maternal hemodynamic changes and neonatal acid-base status were assessed in 127 healthy patients undergoing elective cesarean section under epidural anesthesia. An impedance cardiograph was used to measure stroke volume (SV), ejection fraction (EF) and end-diastolic volume (EDV). In addition, neonatal umbilical venous and arterial PO2, PCO2, pH, base excess, lactate, pyruvate, excess lactate, and L/P ratio were measured at birth. Patients were divided into three groups. Group 1 (n = 53) required no vasopressor (normotensive controls). In Group 2 (n = 37), mean blood pressure (BP) decreased from 90 mmHg (13.3 kPa). In Group 3 (n = 37), BP decreased from 83 mmHg to 62 mmHg (11.1 to 8.2 kPa), and phenylephrine was administered in 100 micrograms increments to maintain systolic BP greater than 100 mmHg (13.3 kPa). In Groups 2 and 3 the SV and EDV decreased 43% and 33% respectively when hypotension developed. Both vasopressors restored BP, SV and EDV to near baseline values. Neonatal Apgar scores and acid-base profiles were not significantly different among the three groups of neonates, nor were they different between the two hypotensive groups. It is concluded that: 1) transient maternal hypotension does not affect neonatal acid-base status; 2) both ephedrine and phenylephrine increase cardiac preload; and 3) an alpha agent like phenylephrine does not cause fetal acidosis when used for treating maternal hypotension.

The maternal hemodynamic effects of bupivacaine‐epinephrine mixture used for obstetrical anesthesia

“…Blood pressure was measured with an automated blood pressure device (Dinamp, Critikon Inc., Tampa, FL 33630). An impedance cardiograph (Instrumentation for Medicine, Greenwich, C T 06830) and a phonocardiograph (Hewlett-Packard, Andover, MA 0 1810, frequency range 100-500 Hz) were used to measure stroke volume (SV), preejection period (PEP) and ventricular ejection time (VET) (6). A multichannel strip chart recorder was used to record simultaneously ECG, impedance cardiogram and phonocardiogram.…”

“…At delivery, maternal arterial (MA) and neonatal umbilical venous (UV) and arterial (UA) blood samples were obtained for the measurement of pH, Po, and Pco,. The use of the impedance cardiograph to obtain PEP, VET and SV has been extensively described (6)(7)(8). The impedance tracings were read by one of the authors blinded to the type of local anesthetic solution used.…”

“…Garrard's equation was used for calculating ejection fraction from STI (6,11). The basis of using PEP/VET ratio to derive EF has been validated before (6,12). End diastolic volume (EDV) was calculated by dividing SV by EF.…”

Epidural compared with general anaesthesia for caesarean delivery in conscious women with eclampsia

“…Concerns have been expressed about the use of ephedrine in severe pre±eclampsia because these women may be very sensitive to pressor agents. Several authors 20,21 have found that increments of ephedrine given by bolus intravenous injections are a simple therapeutic measure against hypo-tension in women with pre±eclampsia receiving epidural anaesthesia. Ephedrine gives better control of blood pressure with a signi®cant reduction in the risk of nausea and vomiting, and in these studies was not associated with uterine hypertonicity or constriction of the uteroplacental blood supply.…”

Circulatory pathophysiology and options in hemodynamic management during adult liver transplantation

“…The redistributive effects of venoconstriction could be as important as the chronotropic or inotropic stimulation in improving cardiac output. 72,73 In addition, ␣ stimulation may increase the abnormally low vascular tone in conductance vessels of patients with liver disease. 15…”