Effects of Carbon Dioxide Insufflation on Hemodynamics and Arterial Blood Gas Tension during Thoracoscopy under General Anesthesia / 대한마취과학회지

BACKGROUND: Video-assisted thoracic surgical procedure via thoracoscopy has recently gained popularity, as it avoids a thoracotomy, reducing intraoperative blood loss, postoperative pain, respiratory dysfunction and hospital stay. However, to visualize adequately the intrathoracic structures, creation of artificial pneumothorax by carbon dioxide insufflation during thoracoscopy would cause significant hemodynamic compromise. The aim of this study was to evaluate the effect of CO2 insufflation into the pleural cavity on the hemodynamics and the arterial blood gas tension under general anesthesia. METHODS: Twenty-five patients, after intubation with single lumen endotracheal tube, underwent enflurane (1~2%) and N2O-O2 (1:1) general anesthesia. Before placement of a thoracoscope, the baseline mean arterial pressure and heart rate were obtained. Measurements were taken at 5, 10, and 20 min. after the beginning of carbon dioxide insufflation (3~5 mmHg) and 10 min. after gas evacuation. Blood gas analyses were done before, during CO2 insufflation and after CO2 evacuation. Data were analyzed using Student t-test. RESULTS: Positive-pressure CO2 insufflation (3~5 mmHg) caused a decrease of mean arterial pressure (5~7%) and an increase of airway pressure (1.5 times) and heart rate (13~20%) throughout the gas insufflation period (p<0.05). Blood gas analyses revealed no significant change. CONCLUSIONS: These results suggest that low CO2 insufflation pressures (3~5 mmHg) may cause cardiovascular depression during thoracoscopy. Therefore careful monitorings should be done during this procedure.

Effects of Sodium Nitroprusside on Functional Recovery of Stunned Myocardium in Dogs / 대한마취과학회지

Ischemia/reperfusion injury (myocardial stunning) may be mediated by oxygen derived-free radicals. Sodium nitroprusside (SNP), NO-donor, is known to reduce superoxide concentrations in isolated vascular tissue. To explore the efficacy of SNP on myocardial reperfusion injury, 23 halothane-anesthetized dogs underwent 15 minutes of left anterior descending coronary ary (LAD) occlusion and 3 hours of reperfusion. Animals were randomly assigned to receive either saline (n=11) or SNP infusion (n= 10, 10 ug/kg/min) through intracoronary catheter (24G) for 60 minutes beginning 15 minutes before LAD occlusion. Time course of recovery of regional myocardial function (calculated as Mw, slope of the preload recruitable stroke work curve,% SS, percent systolic shortening ; IMP, peak systolic intramyocardial tissue pressure; RSW, regional stroke work) and LAD coronary blood flow (CBF) as well as global myocardial functions were determined in SNP-treated and control groups. The results are as follows; 1) LAD occlusion produced a significant reduction (p<0.01) in Mw, % SS, IMP, and RSW in both the saline and SNP groups without significant differences between two groups except IMP. 2) Mw and IMP recovered to the baseline value by 15 and 60 min of reperfusion in the SNP group, whereas 120 and 180 min in the saline group, respectively. 3) At 3 hrs of reperfusion, % SS were 20% and 56% of the baseline values in the saline and SNP groups, respectively. The degree of recovery in % SS in the SNP group was greater than that in the saline group during early reperfusion. 4) CBF was higher in the SNP group as compared with the saline group throughout the reperfusion period. 5) Global myocardial function showed no significant differences between the two groups except a lower mean arterial pressure during SNP infusion in the SNP group. These findings suggest that intracoronary adminstration of SNP significantly attenuates regional regional myocardial dysfunction associated with transient episodes of ischemia. The protective mechanism of SNP may be related to attenuation of endothelial dysfunction and to decreased consumption during coronary occlusion.

The Effect of Clonidine and Propranolol Premedication on the Hemodynamic Response to Tracheal Intubation / 대한마취과학회지

Tracheal intubation is accompanied by varying degrees of sympathetic stimulation as reflected by increases in heart rate and blood pressure. Several clinical trals to reduce these effects on blood pressure and heart rate by employing phar-macologic agents such as alpha-and beta-blockers, calcium channel blockers, narcotics and lidocaine have been reported. To evaluate the effect of clonidine and propranolol on the hemodynamic changes induced by intubation, we administered clonidine (5 ug/kg or 10 ug/kg. p.o.) or propranolol (160 mg, p.o.) 1 hour before induction of anesthesia, and measured heart rate, systolic pressure, diastolic pressure, and mean pressure before induction, after induction and 1, 3, 5, 10, 30 minutes after intubation. The results were as follows. 1) In the control group, intubation caused a significant increase in heart rate (34%) and blood pressure (31%) 1 minute after intubation, but blood pressure returned to normal level within 5 minutes and increases in heart rate continued to 10 minutes after intubation. 2) Increase in heart rate induced by intubation was attenuated by high dose of clonidine (10ug/kg) and propranolol (160 mg), but was not attenuated by low dose of clonidine (5 ug/kg). 3) Pressor effect elicited by intubation was attenuated by high dose of clonidine, but was not affected by low dose of clonidine and propranolol. Above results suggested that oral clonidine one hour before scheduled anesthesia can be a help to reduce to pressor effect and chronotropic effect of intubation.