Maternal Hemodynamic Variables Research Articles

Comparison of Effect of Norepinephrine Versus Phenylephrine Prophylactic Boluses on Spinal Anesthesia-Induced Hypotension During Elective Cesarean Delivery: A Double-Blind, Randomized, Clinical Study

Background: Spinal anesthesia (SA) onset induces maternal hypotension, which can be managed by vasopressors like phenylephrine (PE). However, PE (α-adrenergic agonist) tends to reflexively decrease the heart rate (HR) and cardiac output (CO). Norepinephrine (NE), being an α-agonist with weak β-adrenergic activity, maintains the blood pressure (BP) with less tendency to decrease the HR and CO, and hence, may be a more useful alternative to PE. Objectives: To compare the effects of prophylactic boluses of NE and PE on SA-induced hypotension during elective cesarean section, as well as assess the neonatal outcomes and adverse reactions. Methods: Sixty parturient belonging to ASA class I and II, scheduled for elective cesarean section, were randomly allocated between 2 groups: (i) Group NE (n=30) which received 5 µg intravenous (IV) NE, and (ii) Group PE (n=30) which received 50 µg IV PE as prophylactic boluses immediately after patient repositioning. Rescue bolus interventions using 5 µg NE or 25 µg PE were given for hypotension, respectively. Maternal hemodynamic variables were measured non-invasively. Neonatal outcomes and adverse effects, if any, were also noted and compared. Results: Pre-operative and post-operative hemodynamic parameters (HR, SBP, DBP, MAP, SpO2), adverse incidences (of hypotension, bradycardia, and nausea) as well as neonatal outcomes were comparable between the two groups (P>0.05). However, the number of patients who required additional rescue vasopressor boluses was significantly greater in Group PE than in Group NE (OR for 2 vs 0 bolus = 9.75; OR for 2 vs. 1 bolus = 11.1428). Conclusion: NE was more efficacious in preventing SA-induced hypotension with better preservation of maternal HR than PE, and hence, can be considered as an alternative to PE.

COMPARATIVE STUDY BETWEEN NOREPINEPHRINE BOLUS AND NOREPINEPHRINE INFUSION IN PREVENTION OF POST-SPINAL HYPOTENSION IN CESAREAN SECTION

Background: Post-spinal hypotension in patients of cesarean section (CS) remains a common scenario in our practice with an incidence of hypotension is up to 71%. Norepinephrine is potent α adrenergic receptor and a weak β adrenergic agonist. It is suitable for maintaining blood pressure as phenylephrine and ephedrine in cesarean section. Objectives: The aim of this work was to evaluate and compare the effects of prophylactic bolus norepinephrine and norepinephrine infusion on blood pressure during spinal anesthesia for cesarean section. Patients and Methods: Eighty patients of American Society of Anesthesiology (ASA) physical status (I-II), aged (20-40) years old and undergoing to elective cesarean section who randomly classified into 2 equal groups: Group (I) received prophylactic bolus norepinephrine (10 μg) and Group (II) received prophylactic norepinephrine infusion (0.05 μg/kg/min). Fixed rate infusion and bolus dose of norepinephrine started immediately after spinal anesthesia. Results: There were significant differences between group I and group II as regards maternal hemodynamic variables which was needed multiple doses of noradrenalin in group II. There were no significant differences in the intraoperative nausea and vomiting between groups. There were no significant differences between group I and group II as regards the fetal outcome. Conclusion: Prophylactic bolus of norepinephrine and prophylactic norepinephrine infusion were effective for maintaining blood pressure of spinal anesthesia in cesarean section, and safe on maternal and fetal status. Norepinephrine infusion was superior to the intermittent boluses.

An open-label randomized controlled clinical trial for comparison of continuous phenylephrine versus norepinephrine infusion in prevention of spinal hypotension during cesarean delivery

BackgroundDuring spinal anesthesia for cesarean delivery phenylephrine is the vasopressor of choice but can cause bradycardia. Norepinephrine has both β- and α-adrenergic activity suitable for maintaining blood pressure with less bradycardia. We hypothesized that norepinephrine would be superior to phenylephrine, requiring fewer rescue bolus interventions to maintain blood pressure. MethodsEighty-five parturients having spinal anesthesia for elective cesarean delivery were randomized to Group P (phenylephrine 0.1μg/kg/min) or Group N (norepinephrine 0.05μg/kg/min) fixed-rate infusions. Rescue bolus interventions of phenylephrine 100μg for hypotension, or ephedrine 5mg for bradycardia with hypotension, were given as required to maintain systolic blood pressure. Maternal hemodynamic variables were measured non-invasively. ResultsThere was no difference between groups in the proportion of patients who required rescue vasopressor boluses (Group P: 65.8% [n=25] vs. Group N: 48.8% [n=21], P=0.12). The proportion of patients who received ⩾1 bolus of phenylephrine was similar between groups (Group P: 52.6% [n=20] vs. Group N: 46.5% [n=20], P=0.58). However, more patients received ⩾1 bolus of ephedrine in the phenylephrine group (Group P: 23.7% [n=9] vs. Group N: 2.3% [n=1], P<0.01). The incidence of emesis was greater in the phenylephrine group (Group P: 26.3% vs. Group P: 16.3%, P<0.001). Hemodynamic parameters including heart rate, the incidence of bradycardia, blood pressure, cardiac output, cardiac index, stroke volume, and systemic vascular resistance and neonatal outcome were similar between groups (all P<0.05). ConclusionNorepinephrine fixed-rate infusion has efficacy for preventing hypotension and can be considered as an alternative to phenylephrine.

Remifentanil at induction of general anesthesia for cesarean section: Double blind, randomized clinical trial

Remifentanil, with its rapid activity onset and short duration of action, may be more effective than other opioids for providing hemodynamic stability during obstetric anesthesia. However, there is some evidence of adverse effects on neonatal respiratory function. We investigated maternal and fetal effects of Remifentanil during cesarean section surgery. Eighteen women with singleton term pregnancies, and physical class status of I or II as defined by the American Society of Anesthesia (ASA), who were undergoing general anesthesia for semi-elective cesarean section were randomized into two groups (40 in each group) that received either an intravenous bolus of 0.5 µg/kg Remifentanil or the same dose of saline as a placebo. Maternal hemodynamic variables and neonatal umbilical artery pH and Apgar score at first and fifth min were evaluated in both groups. Systolic and diastolic blood pressure were significantly lower after tracheal intubation and skin incision in the Remifentanil group as compared with the control group (p <0.05). There were no significant differences regarding heart rate between groups at any time (p > 0.05). Apgar scores at first and fifth min were not significantly different among groups (p>0.05). No neonate required assisted ventilation or naloxan administration. Remifentanil may be a safe and effective drug for the induction of general anesthesia and surgical stimulation without subsequent neonatal depression.

Cardiac Index in Term Pregnant Women in the Sitting, Lateral, and Supine Positions

Aortocaval compression may affect maternal hemodynamic indices and fetal well-being in various maternal positions. There has been much debate regarding the optimal position for performing neuraxial blockade for labor analgesia and cesarean delivery. We hypothesized that in pregnant women at term, cardiac index (CI) may be improved in the lateral positions as compared with the flexed sitting position. Our primary outcome was to measure CI as assessed by suprasternal Doppler. A prospective, observational, crossover study was conducted in 25 ASA physical status I/II women with uncomplicated pregnancies presenting for elective cesarean delivery at term. Hemodynamic indices were measured in 4 positions in random order: supine with a 15-degree left tilt, sitting with neck and hips flexed, and flexed left lateral and flexed right lateral positions. Maternal CIs were measured using a noninvasive suprasternal Doppler device and upper arm noninvasive arterial blood pressure. Umbilical Dopplers were performed simultaneously to measure the fetal heart rate and umbilical artery pulsatility and resistivity indices. CI differed by position (P = 0.01); it was higher in the right lateral position compared with the sitting and supine positions (by 8.8% and 8.1%, respectively) and in the left lateral compared with sitting position (by 7.8%) (P < 0.05). Maternal stroke volume index, heart rate, and systolic blood pressure were higher in the lateral positions compared with the sitting and supine-tilt positions. We found no significant differences in fetal heart rate, pulsatility index, or resistivity index among positions. Positioning for neuraxial anesthesia may influence maternal hemodynamic variables. We found no difference in healthy fetal blood flow indices among positions, suggesting that these changes are not clinically significant. This study provides new physiological information on the changes that occur in a group in whom it has not been practical to study previously. Further study is necessary to determine whether these changes are significant in the presence of neuraxial anesthesia or in the high-risk parturient.

Effect of Parity on Maternal Cardiac Function During the First Trimester of Pregnancy

Objective To investigate maternal cardiac adaptation in the first trimester of pregnancy with increasing maternal parity. Methods This was a cross-sectional study carried out at the antenatal clinic of a teaching hospital. We examined 4689 pregnant women at 11 + 0 to 13 + 6 weeks of gestation, performing two-dimensional echocardiography of the maternal left ventricle. There were 2352 parous and 2337 nulliparous women. The relationships between parity, maternal cardiac function and neonatal birth weight were analyzed. Results Parous compared to nulliparous women had a significantly higher median cardiac output (5.6 vs. 5.2 L/min) and median cardiac index (2.3 vs. 2.1 L/min/m2). This was owing to a significantly higher median stroke volume (73.5 vs. 70.5 mL), heart rate (76 vs. 75 bpm), left ventricular outflow diameter (20.4 vs. 20.0 mm) and lower total vascular resistance (1190.8 vs. 1253.7 dyne·s/cm5) and median uterine artery pulsatility index (1.6 vs. 1.7). Mean arterial blood pressure was not significantly different between the groups. There was a progressive increase in all maternal cardiac variables, apart from total peripheral resistance, which decreased with increasing parity. Birth weight was higher in parous compared to nulliparous women (3.39 vs. 3.23 kg) and it was independently related to maternal hemodynamic variables and demographic and social characteristics (age, height, weight, ethnicity, smoking). Conclusion Pregnancy in parous compared to nulliparous women is characterized by higher maternal cardiac output and birth weight. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.

Effect of parity on maternal cardiac function during the first trimester of pregnancy

To investigate maternal cardiac adaptation in the first trimester of pregnancy with increasing maternal parity. This was a cross-sectional study carried out at the antenatal clinic of a teaching hospital. We examined 4689 pregnant women at 11 + 0 to 13 + 6 weeks of gestation, performing two-dimensional echocardiography of the maternal left ventricle. There were 2352 parous and 2337 nulliparous women. The relationships between parity, maternal cardiac function and neonatal birth weight were analyzed. Parous compared to nulliparous women had a significantly higher median cardiac output (5.6 vs. 5.2 L/min) and median cardiac index (2.3 vs. 2.1 L/min/m(2)). This was owing to a significantly higher median stroke volume (73.5 vs. 70.5 mL), heart rate (76 vs. 75 bpm), left ventricular outflow diameter (20.4 vs. 20.0 mm) and lower total vascular resistance (1190.8 vs. 1253.7 dyne s/cm(5)) and median uterine artery pulsatility index (1.6 vs. 1.7). Mean arterial blood pressure was not significantly different between the groups. There was a progressive increase in all maternal cardiac variables, apart from total peripheral resistance, which decreased with increasing parity. Birth weight was higher in parous compared to nulliparous women (3.39 vs. 3.23 kg) and it was independently related to maternal hemodynamic variables and demographic and social characteristics (age, height, weight, ethnicity, smoking). Pregnancy in parous compared to nulliparous women is characterized by higher maternal cardiac output and birth weight.

Uso del remifentanilo en bolus en la cesárea de la paciente de alto riesgo: Estudio sobre 12 casos

To evaluate the utility and safety of remifentanil for hemodynamic control during cesarean section in high-risk patients ineligible for spinal anesthesia. One minute before induction we injected a bolus of 1 microg x kg(-1) of remifentanil, followed by propofol (2.5 mg x kg(-1)), succinylcholine (1 mg x kg(-1)), cisatracurium, sevoflurane in oxygen and nitrous oxide, and fentanyl (5 microg x kg(-1)) after clamping the umbilical cord. We recorded maternal hemodynamic variables, pulse oximetry, capnography, bispectral index, and presence of muscular rigidity. In the neonate we assessed fetal wellbeing, weight, and requirement for naloxone. Hemodynamic stability was defined as no more than 15% variation in arterial pressure with respect to baseline. Twelve patients undergoing surgery because of placenta abruptio, subarachnoid hemorrhage, HELLP syndrome, or preeclampsia were enrolled. Hemodynamic variables were consistently stable during surgery in all patients. No cases of neonatal rigidity were noted and there was no need for naloxone. The mean Apgar score was 6.42 (1.5) at 1 minute and 8.42 (0.9) at 5 minutes. Bolus injection of 1 microg x kg(-1) of remifentanil may be useful for maintaining maternal hemodynamic stability in high-risk obstetric cases. Given the risk of neonatal depression, this resource should be used selectively and the means for neonatal resuscitation should be available.

Intraabdominal carbon dioxide insufflation in the pregnant ewe. Uterine blood flow, intraamniotic pressure, and cardiopulmonary effects.

Laparoscopic surgical procedures are being performed in pregnant women with increasing frequency. Maternal-fetal physiologic changes occurring during intraabdominal carbon dioxide insufflation are poorly understood, and maternal-fetal safety is of concern during carbon dioxide pneumoperitoneum. A previous pilot study using end-tidal carbon dioxide-guided ventilation resulted in maternal and fetal acidosis and tachycardia during carbon dioxide pneumoperitoneum. Using serial arterial PCO2 to guide ventilation, this study was designed to evaluate maternal-fetal cardiopulmonary status, uterine blood flow, and the intraamniotic pressure effects of intraabdominal carbon dioxide insufflation in singleton pregnant ewes between 120 and 135 days of gestation. In a prospective randomized cross-over study, nine ewes were to receive either abdominal insufflation with carbon dioxide to an intraabdominal pressure of 15 mmHg (n = 9; insufflation group) or receive no insufflation (n = 9; control group). Anesthesia was induced with thiopental and maintained with end-tidal halothane (1 to 1.5 minimum alveolar concentration/100% oxygen). Mechanical ventilation was guided by serial maternal arterial blood gas analysis to maintain PaCO2 between 35 and 40 mmHg. Data from insufflated animals were collected during insufflation (60 min) and after desufflation (30 min). Control group data were collected and matched to similar time intervals for 90 min. Ewes were allowed to recover, and after a rest period (48 h) they were entered in the cross-over study. During insufflation there was a significant increase (P < 0.05) in maternal PaCO2 to end-tidal carbon dioxide gradient and minute ventilation, with concomitant decreases in maternal end-tidal carbon dioxide and PaO2. Intraamniotic pressure increased significantly during insufflation. No significant changes were observed in maternal hemodynamic variables, fetal variables, or in uterine blood flow during the study. There were no fetal deaths or preterm labor in any of the animals during the experiment. During the 1-h insufflation, a marked increase in PaCO2-to-end-tidal carbon dioxide gradient was observed, suggesting that capnography may be an inadequate guide to ventilation during carbon dioxide pneumoperitoneum in the pregnant patient. No other significant circulatory changes were observed.

The Effects of Varying Volumes of Crystalloid Administration Before Cesarean Delivery on Maternal Hemodynamics and Colloid Osmotic Pressure

The value of intravenous crystalloid administration in preventing spinal-induced hypotension in the parturient has recently been questioned. Also, the association between increasing crystalloid volume and decreasing postpartum colloid osmotic pressure (COP) raises concern regarding the risk of maternal and fetal pulmonary edema. To study the dose-response effect of varying amounts of crystalloid volume prior to spinal anesthesia, we measured maternal hemodynamic variables and maternal and fetal COP in three groups of healthy parturients receiving spinal anesthesia for elective cesarean delivery. Fifty-five parturients were randomized in a double-blind fashion to receive one of 10, 20, or 30 mL/kg of crystalloid volumes prior to induction of spinal anesthesia. Measurements included mean arterial blood pressure (MAP), cardiac index (CI), and systemic vascular resistance index (SVRI) recorded using noninvasive thoracic impedance monitoring until delivery. Maternal and neonatal COP were measured. All groups showed declines in MAP and SVRI from baseline at 5 min after spinal anesthesia, but the amount of decline did not differ among groups. Total ephedrine and additional intravenous (i.v.) fluid administered did not differ among groups. The 20- and 30- mL/kg groups showed a larger decline in maternal COP than the 10-mL/kg group; no differences in neonatal COP were seen with varying preload. We conclude that increasing the amount of i.v. crystalloid administered to 30 mL/kg in the healthy parturient does not significantly alter maternal hemodynamics or ephedrine requirements after spinal anesthesia and has no apparent benefit.