Lidocaine cardioplegia for prevention of reperfusion ventricular fibrillation.

Lidocaine addition to crystalloid cardioplegic solution for prevention of reperfusion ventricular fibrillation after the release of the aortic cross-clamp was studied in 50 patients undergoing coronary artery bypass grafting and in 30 patients undergoing mitral or aortic valve replacement. Twenty-six of the patients undergoing coronary artery bypass grafting received lidocaine, 100 mg/L of cardioplegia, whereas a control group of 24 patients received cardioplegia without lidocaine. In the group undergoing valve replacement, 14 patients received lidocaine cardioplegia and 16 patients served as control. In the coronary artery bypass grafting group, lidocaine cardioplegia reduced significantly the incidence of reperfusion ventricular fibrillation from 100% to 42%. In the valve group, lidocaine cardioplegia also reduced significantly the incidence of reperfusion ventricular fibrillation from 93% to 42%. In both groups, lidocaine cardioplegia decreased the number of direct-current countershocks required to defibrillate the heart, with no significant increase in the incidence of high-grade atrioventricular block.

Prediction of post-cardiopulmonary bypass cardiac output by venous oximetry.

The present study evaluates two equations for predicting the post-cardiopulmonary bypass cardiac output (CO) in 10 patients undergoing coronary artery bypass grafting. One equation is based on the relationship of CO with mixed venous oxygen saturation (SVO 2), while the second equation is based on the relationship with oxygen extraction (1 - SVO 2). Each patient served as his own control. During bypass, when the patients were normothermic and perfused with a pump flow of 2.4 L/min/m 2, the SVO 2 was monitored by an in-line Bentley oxystat Meter. Just before termination of bypass, the pump flow was decreased to 0.4 L/min/m 2 and the left atrial pressure was increased to 10-15 mmHg; the resulting SVO 2 was recorded. The post-bypass CO was predicted in every patient by the two equations. Immediately after weaning from bypass, the cardiac output was measured by thermodilution. The thermodilutional CO measurement was correlated with the CO predicted by the two equations. Correlation analysis suggests that CO prediction is more accurate and approaches the 1:1 ratio when the calculation of predicted CO is based on the relationship between cardiac output and oxygen extraction.

Ondansetron versus dehydrobenzoperidol and metoclopramide for management of postoperative nausea in laparoscopic surgery patients.

BACKGROUND: In this prospective, randomized, double-blind study, we compared the efficacy of ondansetron versus dehydrobenzoperidol (droperidol) or metoclopramide in the treatment of established postoperative nausea and vomiting in 200 adult patients undergoing laparoscopic surgery under general anesthesia. METHODS: One hundred seventy-three American Society of Anesthesiologists (ASA) I and II patients satisfied inclusion criteria. Fifty-seven patients received ondansetron 4 mg (group O), 57 patients were given droperidol 1.25 mg (group D), and 59 patients received metoclopramide 10 mg (group M). Antiemetic efficacy was compared at 10 minutes and 30 minutes after the administration of the study drug. RESULTS: At 10 minutes, nausea scores in group O dropped from 8.3 to 3.7, in group D from 8.5 to 5, and in group M from 8.4 to 6.7; (P < 0.05 between the three groups). At 30 minutes, nausea scores were 1.3 in group O, 1.7 in group D, and 5 in group M; (P < 0.05 between group M and the other two groups). In the droperidol group, 25% of patients developed sedation. Patient satisfaction was best with ondansetron. CONCLUSIONS: Both ondansetron and droperidol were more effective in the treatment of established postoperative nausea and vomiting than was metoclopramide. However, patients were satisfied best with ondansetron, which acts faster and causes less sedation than droperidol.

Post-laparoscopic vomiting in females versus males: comparison of prophylactic antiemetic action of ondansetron versus metoclopramide.

BACKGROUND AND OBJECTIVES: The incidence of postoperative vomiting in patients undergoing laparoscopic cholecystectomy is compared in females versus males. The report also compares the prophylactic action of ondansetron versus metoclopramide. METHODS: A total of 85 American Society of Anesthesiologists (ASA) I and II patients were enrolled in the study. Patients were divided into two groups according to sex: Group I 53 females, and Group II 32 males. After anaesthetic induction, subjects received intravenously either 4 mg ondansetron or 10 mg metoclopramide. RESULTS: The incidence of vomiting as well as the frequency of emetic episodes over 24 hours were analyzed in each group using X2 analysis. Data analysis revealed a significantly higher incidence (P < 0.05) of postoperative emesis in females 10:53 (18.9%) as compared to males 0:32 (0%). In the male group, no patient vomited postoperatively, whether prophylactic ondansetron or metoclopramide was used. While the incidence of emesis in the female group was lower (P < 0.05) in the ondansetron group (17.6%) than the metoclopramide group (29.6%). CONCLUSION: These results may indicate prophylactic antiemetic therapy in female patients undergoing laparoscopic cholecystectomy; ondansetron appears to be superior to metoclopramide.

The hemodynamic effects of intravenous norepinephrine versus epinephrine and phenylephrine in patients with ischemic heart disease.

The hemodynamic effects of an intravenous bolus of norepinephrine 10 micrograms, phenylephrine 100 micrograms and epinephrine 10 micrograms were investigated in 30 patients scheduled for coronary artery bypass grafting. The hemodynamic changes following norepinephrine were similar to those achieved by phenylephrine. Both drugs increased the mean blood pressure and systemic vascular resistance without any significant change of cardiac output. In contrast, epinephrine increased the mean arterial pressure and cardiac output without a significant change of systemic vascular resistance. The results suggest that intravenous norepinephrine acts similar to phenylephrine as an alpha-adrenergic agonist, while epinephrine acts predominantly as a beta-adrenergic agonist.

Action of propofol on resistance and capacitance vessels during cardiopulmonary bypass.

The peripheral vascular action of propofol on the resistance and the capacitance vessels was investigated in 16 patients during cardiopulmonary bypass. The venous reservoir (RV) and mean arterial pressure (MAP) were used as indices of the changes in venous capacitance and systemic vascular resistance (SVR), respectively. Propofol 2 mg.kg-1 produced a decrease in MAP without a significant change in RV, suggesting that propofol preferentially decreases SVR without a significant change in venous capacitance.

Lidocaine for prevention of reperfusion ventricular fibrillation after release of aortic cross-clamping.

OBJECTIVE: To determine the efficacy of a bolus of lidocaine administered by way of the pump before releasing the aortic cross-clamp (ACC) in preventing the occurrence of reperfusion ventricular fibrillation. DESIGN: Prospective, randomized study. SETTING: University hospital. PARTICIPANTS: Patients undergoing coronary artery bypass graft surgery (n = 34). INTERVENTIONS: Seventeen patients received 100 mg of lidocaine by way of the pump 2 minutes before releasing the ACC, and a control group of 17 patients received 5 mL of normal saline. MEASUREMENTS AND MAIN RESULTS: In the control group, the incidence of reperfusion ventricular fibrillation was 70%, which was significantly decreased to 11% in the lidocaine group. A higher cardiac output after weaning from cardiopulmonary bypass was observed in the lidocaine group; this may be attributed to the lower incidence of reperfusion ventricular fibrillation and consequently the lower need for defibrillation by electric countershocks. CONCLUSIONS: The results suggest that a bolus of 100 mg of lidocaine administered 2 minutes before release of the ACC can safely decrease the incidence of reperfusion ventricular fibrillation and is associated with better hemodynamics after weaning from cardiopulmonary bypass.

Awareness following different techniques of general anaesthesia for caesarean section.

Using the isolated arm technique, the frequency of awareness was evaluated in 50 full-term patients undergoing elective Caesarean section under general anaesthesia. In 20 patients, anaesthesia was induced with thiopentone 4 mg kg-1, and in the other 30 patients, induction was with ketamine 1.5 mg kg-1. Following suxamethonium 1.5 mg kg-1 and tracheal intubation, anaesthesia was supplemented during the induction-delivery period in the thiopentone group with 50% nitrous oxide and 0.5% halothane in oxygen in 10 patients, and with 1% halothane in 100% oxygen in the other 10 patients. In the ketamine group, the patients underwent ventilation with 50% nitrous oxide and 0.5% halothane in oxygen in 10 patients, with 1% halothane in 100% in 10 patients, and with 100% oxygen only in the last 10 patients. Awareness was significantly greater after induction with thiopentone (14/20) than after ketamine (4/30). There were no significant differences in Apgar scores or umbilical vein blood-gas values in the newborns.

Continuous venous oximetry during cardiopulmonary bypass: influence of temperature changes, perfusion flow, and hematocrit levels.

This study was performed in 11 patients undergoing cardiac surgery during cardiopulmonary bypass (CPB). A Bentley-10 oxygenator (American Bentley, Irvine, CA) was used during bypass, and 1,500 mL of Ringer's solution was used to prime the oxygenator. A perfusion flow of 2.4 L/min/m2 was used, and an equivalent flow of 100% oxygen was added to the oxygenator. The mixed venous oxygen saturation (SvO2) was monitored by continuous in-line venous oximetry using the Bentley Oxy-Stat Meter. Body temperature and SvO2 measurements were made at the venous blood port of the oxygenator. The authors investigated the correlation between SvO2 and changes of body temperature, perfusion flow, and hematocrit values. SvO2 correlated inversely, in a linear fashion, with the body temperature. The SvO2 was markedly decreased after rewarming, and was significantly affected during normothermia by changes in perfusion flow rates and hematocrit levels. An adequate SvO2 was found when the flow was greater than 2.4 L/min/m2 and the hematocrit was greater than 20%. In-line oximetry can help to optimize perfusion during CPB and to detect episodes of desaturation.

Effect of alpha-stat versus pH-stat strategy on oxyhemoglobin dissociation and whole-body oxygen consumption during hypothermic cardiopulmonary bypass.

To determine whether alpha-stat or pH-stat strategy should be used, 20 patients undergoing coronary artery bypass grafting during moderate hypothermic hemodilutional cardiopulmonary bypass were studied. The carbon dioxide management during bypass was randomly done according to alpha-stat strategy in 10 patients (i.e., temperature-uncorrected PaCO2 was kept near 40 mm Hg and uncorrected pHa was kept at about 7.4) and according to pH-stat strategy in the other 10 patients (i.e., temperature-corrected PaCO2 was kept near 40 mm Hg and uncorrected pHa was kept at about 7.4). In both groups, when the central venous temperature was stable at 26.5 +/- 2.5 degrees C, the perfusion flow was altered sequentially from 2.4 to 1.8 and 1.2 L.min-1.m-2. The mixed venous oxyhemoglobin saturation at the different perfusion flows was monitored by the Oxy-Stat meter and was correlated with the corresponding mixed venous oxygen tension to construct an oxyhemoglobin dissociation curve. Also, the whole-body oxygen consumption at the different perfusion flows was computed. The whole-body oxygen consumption and the oxyhemoglobin dissociation were not significantly different between the alpha-stat and the pH-stat groups. In both groups, the dissociation curve is shifted to the left, but the oxygen consumption per unit time does not significantly change despite decreasing the perfusion flow from 2.4 to 1.2 L.min-1.m-2. The results suggest that oxygen delivery is not impaired during moderate hypothermic cardiopulmonary bypass independent of whether alpha-stat or pH-stat strategy is used.