Hemodynamics During Laparoscopic Surgery in Pregnancy

Pregnancy is no longer considered a contraindication to laparoscopic surgery. In recent years, numerous authors have reported favorable outcomes with a variety of laparoscopic procedures performed during pregnancy (1–4). In nonpregnant patients, carbon dioxide (CO2) pneumoperitoneum during laparoscopic surgery is accompanied by significant changes in hemodynamics; cardiac index (CI) is significantly reduced, whereas mean arterial blood pressure (MAP) and systemic vascular resistance (SVR) are increased. We hypothesized that physiologic changes of pregnancy may lead to exaggerated cardiovascular responses to CO2 pneumoperitoneum in parturients. We measured cardiac output changes noninvasively by thoracic electrical bioimpedance cardiography in four pregnant women undergoing laparoscopic cholecystectomy. Case Reports We studied four healthy pregnant women at 17, 20, 23, and 24 wk gestational age scheduled for laparoscopic cholecystectomy. Our IRB approved the study protocol and all patients provided written informed consent. Fetal heart rate was evaluated by ultrasound before and after surgery. Left uterine displacement was maintained during anesthesia with a blanket under the right hip. After oral sodium citrate (30 mL) and preoxygenation, general anesthesia was induced with sodium pentothal and succinylcholine and the trachea was intubated with a 7.0 mm endotracheal tube. General anesthesia was maintained with desflurane in air/oxygen, fentanyl and cisatracurium. Peritoneal insufflation of CO2 was limited to peak inflation pressure of 15 mm Hg. Pulmonary ventilation was adjusted to maintain Petco2 around 32 mm Hg. IV ephedrine (10 mg) was given if the systolic blood pressure decreased by more than 20% with respect to baseline. All patients subsequently had uneventful pregnancies and uncomplicated deliveries. Hemodynamic measurements were obtained using a noninvasive thoracic electrical bioimpedance monitor (NCCOM3-R7S; BoMed Medical Manufacturing, Ltd., Irvine, CA). Determinations of heart rate (HR), CI, and SVR were made over 16 heartbeats and recorded every minute. MAP was measured noninvasively every 1–2 min. Values were averaged over 3–5 min periods ending 1) before induction of general anesthesia, 2) after induction and immediately before CO2 insufflation, 3) 5 min after starting CO2 insufflation, 4) 15 min after starting CO2 insufflation, and 5) after tracheal extubation. Mean and sd values for CI, MAP, SVR, and HR for each of the five time periods are shown in Table 1. One-way analysis of variance was used to evaluate differences between the variables in each phase of laparoscopic surgery;P < 0.05 was considered significant. Differences that were significant by analysis of variance were examined using the Student’s t-tests.Table 1: Hemodynamics During Laparoscopic Cholecystectomy in Four Pregnant PatientsDiscussion The cardiovascular effects of CO2 pneumoperitoneum in pregnant patients have not been reported. Hemodynamic effects of CO2 pneumoperitoneum have been detailed in several studies in nonpregnant subjects, as reviewed by Wahba et al. (5). The major cardiovascular changes in nonpregnant patients may be summarized as follows: with induction of anesthesia and head-up tilt, CI decreases by approximately 25%. During CO2 insufflation, there is further depression of CI to approximately 50% of awake values together with increases in MAP and SVR. Partial recovery of CI and SVR follows. The reduction in CI after CO2 insufflation may be delayed by performing CO2 insufflation in the horizontal position (6). Our observations during laparoscopic cholecystectomy in pregnant women were similar to those reported in nonpregnant subjects (5). In four pregnant patients, compared with baseline (preinduction) values, we noted a 27% decrease in CI after 5 minutes of CO2 insufflation; CI remained 21% below base-line after 15 minutes insufflation. MAP decreased by 19% after induction of anesthesia; more profound reductions were prevented by use of ephedrine. Our aggressive management of blood pressures during anesthesia (treating any decrease in blood pressure approaching 20% of baseline measurements with IV ephedrine so as to minimize decreases in uterine blood flow) may have resulted in the somewhat smaller reduction in CI during CO2 insufflation in our patients (27%), as compared to 30%–50% in nonpregnant patients in most studies (5). Both MAP and SVR increased in our patients during insufflation—MAP by 16% after 5 minutes insufflation and by 19% after 15 minutes, whereas SVR increased by 16% after 5 minutes insufflation. After tracheal extubation, CI and HR increased dramatically, achieving values significantly greater than baseline, while SVR declined. Thoracic electrical bioimpedance cardiography is a noninvasive method that provides accurate reproducible estimations of CI comparable to thermodilution methods (7,8). Bioimpedance cardiography has been used to determine changes in CI induced by CO2 pneumoperitoneum during laparoscopic surgery in nonpregnant patients (9,10). Westerband et al. (10) reported a decrease in CI by about 30% on CO2 insufflation, similar to our observation of a 27% decrease in CI when CO2 pneumoperitoneum was induced in parturients. In conclusion, during laparoscopic cholecystectomy in four pregnant women, we observed hemodynamic changes similar to those in nonpregnant patients, i.e., decreases in CI together with increases in MAP and SVR.