Effects of Intracoronary Epinephrine on Coronary Blood Flow, Oxidative Metabolism and Mechanical Function in Normal and Stunned Myocardium in Dogs / 대한마취과학회지

BACKGROUND: Epinephrine is frequently administered during cardiac surgery. The vascular response to epinephrine might be altered by ischemia and reperfusion, since altered vascular control has been demonstrated even after a short period of ischemia. To test the hypothesis, the effects of epinephrine on regional myocardial contractility, coronary blood flow (CBF) and myocardial oxygen consumption (MVO2) were investigated before and after ischemia in an open-chest canine myocardium. METHODS: Fifteen dogs were acutely instrumented under enflurane anesthesia to measure aortic and left ventricular pressures, pulmonary and left anterior descending (LAD) blood flows via Doppler flowmeter, and subendocardial segment length in the region supplied by LAD. Incremental doses of epinephrine (4, 10, 20, 30 ng/mL of LAD flow) were infused directly into LAD before (normal) and after a 15 min of LAD occlusion and subsequent 30 min-reperfusion (stunned). Segment shortening (%SS), as an index of regional myocardial contractility was evaluated. Simultaneous arterial and coronary venous contents of oxygen and lactate were measured during epinephrine (0.0, 4, 10, and 30 ng/mL) infusion. Effectiveness of metabolic vasodilation was determined from oxygen extraction ratio (EO2). RESULTS: Epinephrine infusions before ischemia resulted in dose-dependent increases in %SS and MVO2. These changes were accompanied by excessive increases in CBF, resulting in decreased EO2. After the ischemia and reperfusion, %SS was depressed and lactate extraction (Elac) was reduced, but similar mechanical responses to epinephrine were observed. However, in the stunned myocardium, CBF increased in parallel with increases in MVO2, resulting in unaltered EO2. Epinephrine infusion further decreased Elac dose-dependently in stunned myocardium. Heart rate and left ventricular systolic and diastolic pressures were little but similarly affected during epinephrine infusions before and after myocardial ischemia. CONCLUSIONS: The results suggest that epinephrine exerts positive inotropic effects in both normal and stunned myocardium, and that epinephrine causes direct coronary vasodilation in normal myocardium, but this effect is abolished in stunned myocardium in dogs. It is also suggested that epinephrine infusion depresses Elac dose-dependently in stunned myocardium.

Comparison of the Effect of Epinephrine Concentration during Caudal Epidural Anesthesia / 대한마취과학회지

BACKGROUND: The advantages of addition of epinephrine to local anesthetics during caudal epidural anesthesia are core intense block, prolonged duration of anesthesia and reduction of systemic toxic effect of local anesthetics. The currently recommended concentration of epinephrine is 1 : 200,000, but absorbed epinephrines cause unwanted hemodynamic changes, so we attempted to ascertain the minimum effective concentrations of epinephrine during caudal epidural anesthesia. METHODS: Ninty patients classified ASA physical status I or II scheduled for perianal surgery were studied. These patients were divided into four groups who received 20 ml of 2% lidocaine with epinephrine concentrations of 1 : 100,000, 1 : 200,000, 1 : 400,000 or 1 : 800,000 respectively. Before and during anesthesia, patients' mean arterial pressure (MAP) and heart rate (HR) were measured. Caudal anesthesia was performed with patients in the jack-knife position. A 3 ml test dose was administered initially and then the remaining local anesthetics were injected slowly. The onset of analgesia, duration of analgesia, and other complications were observed. RESULTS: The onset of analgesia was slowest in the 1 : 800,000 group. The duration of analgesia was longest in the 1 : 100,000 group. There were no significant difference in MAP changes, but HR increased significantly in the 1 : 100,000 group compared to the 1 : 200,00 group. There were no systemic toxic symptoms for local anesthetics except that 1 patient, who was in the 1 : 100,000 group, had symptoms of palpitation and headache, considered to be the unwanted pharmacologic effects of epinephrine. CONCLUSION: We concluded that the 1 : 400,000 epinephrine concentration can be used during caudal epidural anesthesia.

The Efficacy of Epinephrine Test Doses during Combined Spinal-Epidural Anesthesia in Adult Patients / 대한마취과학회지

BACKGROUND: Combined spinal-epidural anesthesia has been used to reduce the side effect of spinal or epidural anesthesia. The epinephrine test dose to prevent intravascular injection of local anesthetics after subarachnoid block has not been clearly understood. The purpose of present study is to see the efficacy of simulated intravenous test dose during subarachnoid block. METHODS: 20 ASA physical status 1 and 2 patients underwent subarachnoid block with tetracaine 10 mg in hyperbaric solution at the L3-4 interspace and were divided into two groups, Group 1 (n=10) and Group 2 (n=10). 3 ml of Normal saline was injected intravenously to group 1, while 1:200,000 epinephrine 3 ml (15 microgram) was injected intravenously to group 2 at regression of sensory block to T8-10. 1:200,000 epinephrine 3 ml (15 microgram) was given to each volunteer (Group 3, n=10). Heart rate (HR) was measured at 15 seconds intervals for 3 minutes and systolic blood pressure (SBP) was measured at 1 minute intervals for 5 minutes. RESULTS: SBP increased significantly in group 2 and group 3 at 1 minute after epinephrine test dose injection. Maximal HR changes was 39.7 3.7 beat per minute in group 2 and 25.8 5.2 beat per minute in group 3. There was 100% incidence of detection of intravascular injection of 15 microgram epinephrine in both group when HR increase > or = 20 beats per minute is regarded as positive response. CONCLUSIONS: This study demonstrates that the epinephrine test dose is useful method to detect intravascular injection of local anesthetics either in the combined spinal-epidural anesthesia or epidural anesthesia. The heart rate response after injection of epinephrine was greater than the blood pressure response.

Efficacy of a Simulated Epidural Test Dose in Isoflurane-Anesthetized Adults / 대한마취과학회지

BACKGROUND: An epidural test dose containing epinephrine may be incomplete marker of incidental intravenous injection or migration of the epidural catheter in adult patients under general anesthesia. This study tests the hypothesis that the efficacy of simulated epidural test doses in anesthetized adult can be used to predict the adequacy of correct catheter placement. METHODS: Seventy-five healthy adult patients were randomly assigned to inject intravenously one of 5 solutions, either 2% lidocaine 3ml and epinephrine 15 microgram(Group E15, n=15) or epinephrine 20 microgram (Group E20. n=15) or isoproterenol 3microgram (Group I3, n=15) or isoproterenol 5microgram (Group I5, n=15) and 0.9% saline(Group NS, n=15), which was anesthetized with isoflurane and nitrous oxide. After the injection, a blinded observer recorded systolic blood pressure(SBP) and heart rate(HR) every 30seconds for 4minutes and the changes were analyzed. RESULTS: Although none in the saline group developed a HR increase> or20bpm, 6, 10, 12 and 15 patients elicited positive reponses in group E15, I3, E20, and I5(40%, 67%, 80% and 100% sensitivities), respectively. Meanwhile, none in the saline group developed a SBP increase> or15mmHg and 11, 1, 14 and 4 patients elicited positive reponses in E15, I3, E20, and I5(73%, 7%, 93% and 27% sensitivities), respectively. CONCLUSIONS: We conclude that under isoflurane anesthesia, (a) epinephrine 15 microgram or isoproterenol 3microgram is not reliable marker for incidental intravenous injection or migration of the epidural catheter, (b) epinephrine 20 microgram is applicable on SBP criterion and, (c) isoproterenol 5 microgram is applicable on HR criterion.

Effects of Epinephrine on the Voltage Dependent Na+, Ca2+ Channels and Cellular Excitability in Dorsal Root Ganglion Neurons, and Its Interaction with Tetracaine / 대한마취과학회지

BACKGROUND: The addition of epinephrine to local anesthetics has been known to prolong the duration of neural blokade and to increase the intensity of analgesia, but underlying mechanisms are unclear. This study was designed to investigate electrophysiologically the analgesic effects of epinephrine and its interaction with tetracaine. METHODS: Whole cell patch clamp recordings were made from acutely dissociated neurons from adult rat dorsal root ganglion (DRG). Using voltage clamp method, we compared the IC50 values of tetracaine for Na+ and Ca2+ channel suppression in the absence and presence of a fixed dose of epinephrine. Action potentials evoked by current pulses were also investigated to evaluate the effect of tetracaine and epinephrine on the excitability of DRG neurons. RESULTS: Clinical doses of epinephrine did not alter the dose-response curves of tetracaine for peak Na+ and Ca2+ channel current, but the amplitude of action potential spikes was reduced and firing rates evoked by sustained current pulse increased. The addition of epinephrine did not affect the changes of action potential parameters caused by tetracaine alone. CONCLUSIONS: The ability of epinephrine to increase the intensity of analgesia induced by tetracaine seems more likely due to an analgesic action at the level of spinal cord rather than a direct analgesic action at a level of primary sensory neurons. Local vasoconstriction and stimulation of descending inhibitory system via alpha-adrenergic pathway may play a role.

A Comparative Study of Arrhythmogenic Doses of Epinephrine during Sevoflurane or Halothane Anesthesia in the Dogs / 대한마취과학회지

BACKGROUND: Epinephrine used in surgery to provide hemostasis may elicit ventricular arrhythmias. A desirable anesthetic would not sensitize the myocardium to exogenously administered epinephrine. So the effect of sevoflurane, which was introduced to clinical anesthesia recently, on cardiac arrhythmias induced by the infusion of epinephrine was compared with those of halothane which was already known to epinephrine-induced arrhythmia in the 14 mongrel dogs. METHODS: The authors compared the arrhythmogenicity (three or more premature ventricular contractions, PVCs)of intravenously administered epinephrine in 14 mongrel dogs who were randomly assigned to receive sevoflurane (1.7 vol%) or halothane (0.75 vol%) anesthesia equipotently. The arrhythmogenic doses of epinephrine determined in this comparative study were expressed by both infusion rates of epinephrine during sevoflurane and halothane anesthesia. RESULTS: The mean values of the arrythmogenic infusion rates of epinephrine were 27.1 7.6 g/kg for sevoflurane and 2.7 0.8 g/kg for halothane. CONCLUSIONS: We concluded that the arrythmogenic doses of epinephrine during sevoflurane were significantly higher than those during halothane anesthesia.

Effect of Bevel Direction of 25G Spinal Needle and Addition of Epinephrine on Spinal Anesthesia / 대한마취과학회지

BACKGROUND: Distribution of local anesthetics injected into subarachnoid space is determined by many intrinsic & extrinsic factors. The purpose of this study was to compare the spread of spinal anesthetic agent according to the direction of bevel and addition of epinephrine. METHOD: Eighty nine consenting patients, undergoing orthopedic surgery of lower extremities were divided into eight groups to direction of bevel and addition of epinephrine in each direction. In lateral decubitus position, 25-gauge spinal needle was introduced into the subarachnoid space and 1% tetracaine with the same volume of 10% dextrose was injected through the spinal needle. Patients were turned to the supine position and checked sensory block level by pin-prick test at anterior axillary line every 5 minutes. Degree of motor block was measured by Bromage scale and two-segment regression time was measured by pin-prick test every 15 minutes interval after maximal sensory block level was reached. RESULTS: No significant difference in maximum level of sensory block was found among groups. But two segment regression time was significantly prolonged in epinephrine added cephalad and down groups. CONCLUSION: Direction of bevel did not affect maximum level of sensory block and duration of spinal anesthesia but, epinephrine prolonged the duration of local anesthetics in special directions.

A Comparative Study of Effects of Netroglycerin , Adenosine Triphosphate and Sodium Nitroprusside on the Hemodynamic and Blood Gas Analysis Changes during Epinephrine Infusion in Air Embolized Cats / 대한마취과학회지

Effects of nitroglycerin (NTC), adenosine triphosphate (ATP) and sodium nitroprusside (SNP) on the hemodynamic and blood gas analysis changes epinephrine (EPI) infusion is air embolized cats were investigated. Under the general anesthesia with pentobarbital and vecuronium cats were given 2~2.5 ml/kg of air via internal jugular vein and were resuscitated with EPI bolus injection. Thirty two cats were divided into 4 groups of 8 each. Each 4 groups, were administered saline (group1), NTG (group 2), ATP (group 3) and SNP (group 4) with EPI continuous infusion, respectively. The air shadow in the heart of cats was visualized C-arm image intensifier throught the study and all three vasodilators augmented the removal of air from the heart on C-arm image. All three vasodilators therapy groups produced statistically significant decrease in rate pressure product (p<0.05) but only NTG therapy group decreased heart rate (p<0.05). Central venous pressure were decreased in all three vasodilators therapy groups but only NTG therapy group was statistically significant (p<0.05). Only NTG therapy group increased both arterial (p<0.05) and venous oxgenation. These results indicate that NTG therapy group produced more prominant hemodynamic and blood oxygenation improvement than the other three groups. It is concluded that NTG with vasopressor therapy coude be recommended in venous air embolism.

A Comparative Study of Effects of Netroglycerin , Adenosine Triphosphate and Sodium Nitroprusside on the Hemodynamic and Blood Gas Analysis Changes during Epinephrine Infusion in Air Embolized Cats / 대한마취과학회지

Effects of nitroglycerin (NTC), adenosine triphosphate (ATP) and sodium nitroprusside (SNP) on the hemodynamic and blood gas analysis changes epinephrine (EPI) infusion is air embolized cats were investigated. Under the general anesthesia with pentobarbital and vecuronium cats were given 2~2.5 ml/kg of air via internal jugular vein and were resuscitated with EPI bolus injection. Thirty two cats were divided into 4 groups of 8 each. Each 4 groups, were administered saline (group1), NTG (group 2), ATP (group 3) and SNP (group 4) with EPI continuous infusion, respectively. The air shadow in the heart of cats was visualized C-arm image intensifier throught the study and all three vasodilators augmented the removal of air from the heart on C-arm image. All three vasodilators therapy groups produced statistically significant decrease in rate pressure product (p<0.05) but only NTG therapy group decreased heart rate (p<0.05). Central venous pressure were decreased in all three vasodilators therapy groups but only NTG therapy group was statistically significant (p<0.05). Only NTG therapy group increased both arterial (p<0.05) and venous oxgenation. These results indicate that NTG therapy group produced more prominant hemodynamic and blood oxygenation improvement than the other three groups. It is concluded that NTG with vasopressor therapy coude be recommended in venous air embolism.