A Comparison of the Effects on Inducing Hypotension and Bradycardia between Esmolol Infusion Alone and Concomitant Use of Neostigmine for MIDCAB Anesthesia / 대한마취과학회지

BACKGROUND: Esmolol has been applied to lower myocardial oxygen consumption and creates a quieter operative field by reducing systemic blood pressure and heart rate but can cause a certain amount of hemodynamic instability during minimally invasive direct vision coronary artery bypass graft (MIDCAB). The aim of this study was to compare the hemodynamic differences between two methods; inducing hypotension and bradycardia between esmolol infusion alone, and concomitant use of neostigmine during MIDCAB anesthesia. METHODS: Twenty MIDCAB patients were randomly allocated into two groups, group E (n = 10) receiving esmolol 0.3 mg/kg/min, group EN (n = 10) receiving esmolol 0.2 mg/kg/min and neostigmine 1.0 mg for induced hypotension and bradycardia during coronary anastomosis. The hemodynamic parameters were evaluated 10 minutes after induction of anesthesia (T1), 10 minutes after beginning of operation (T2), 5 minutes before the end of anastomosis (T3) and 10 minutes after the end of anastomosis (T4). Data were analyzed by ANOVA test for intragroup comparisons, and by T-test for intergroup comparisons with significance set at a P value of < 0.05. RESULTS: Heart rate significantly decreased at T3 in both groups and more in group EN. Systolic blood pressure decreased at T3 in both groups and there were no group differences but more episodes of extreme hypotension in group E. The cardiac index significantly decreased at T3 in both groups and more in group E. There was a small but significant increase in pulmonary capillary wedge pressure at T3 and T4 in group E and no change of central venous pressure in both groups. CONCLUSION: Concomitant use of neostigmine during esmolol infusion produces more reliable induced hypotension and bradycardia than esmolol infusion alone for MIDCAB anesthesia in terms of prevention of myocardial ischemia and easiness of anastomosis technique.

Effects of Sodium Nitroprusside-induced Hypotension under Acute Normovolemic Hemodilution on the Cardiovascular System and Systemic Oxygen Balance in Dogs / 대한마취과학회지

BACKGROUND: To decrease homologuous transfusion and bleeding, Acute Normovolemic Hemodilution (ANH) may be combined with induced hypotension. Tissue oxygen balance may be in danger because of decreased tissue perfusion pressure by induced hypotension and reduced arterial oxygen content by ANH. Thus it is necessary to evaluate effects of induced hypotension combined with ANH on hemodynamics and systemic oxygen balance. METHODS: In 6 mongrel dogs anesthetized with N2O-O2-enflurane and paralyzed with vecuronium, ANH was performed up to half of initial level of hemoglobin with isovolemic pentastarch infusion, and then mean arterial pressure (MAP) was lowered by 30% of the initial value by intravenous administration of Sodium Nitroprusside (SNP). Various hemodynamic parameters were measured before and after ANH and 15, 30, 45 and 60 minutes after induction of hypotension and 15 minutes after the end of hypotension. RESULTS: Heart rate was not changed significantly throughout the study. Central venous pressure increased significantly after ANH but decreased to the initial value after induced hypotension. Systemic vascular resistance showed significant decrease after ANH, more significant decrease after induced hypotension and slight increase after discontinuation of SNP. Cardiac output increased markedly by ANH and maintained during induced hypotension. Oxygen flux decreased significantly after ANH but slightly increased after induced hypotension. Oxygen consumption and Oxygen extraction ratio were maintained throughout the study. There were no acidemia and hypoxemia throughout the study. CONCLUSION: The combined use of ANH and induced hypotension with SNP is safe in the aspect of cardiovascular system and systemic oxygen balance.

The Hemodynamic Changes during Induced Hypotension with Propofol / 대한마취과학회지

BACKGROUND: The studies related to induced hypotention using propofol were rare. So we studied the effectiveness of propofol as induced hypotensive agent in brain aneurysmal surgery. METHODS: The hemodynamic changes during induced hypotension with propofol (propofol-group) and isoflurane(isoflurane group) were observed in patients undergoing aneurysmal surgery. Twenty patients were allocated randomly to receive propofol induction and maintenance, or thiopental sodium induction and isoflurane maintenance for anesthesia. Both groups also received fentanyl, vecuronium, nitrous oxide and oxygen. These hypotensive effects were evaluated before, during and after induced hypotension. Hemodynamic changes were evaluated by measuring systemic arterial blood pressure, heart rate, central venous pressure, pulmonary capillary wedge pressure, cardiac output, systemic vascular resistance and pulmonary vascular resistance. We also compared the ventilatory effect of hypotensive anesthesia by blood gas analysis. RESULTS: There were no significant changes of heart rate, cardiac output, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, central venous pressure and pulmonary vascular resistance before, during and after induced hypotension in both group. Mean arterial pressure and systemic vascular resistance were significantly decresed during induced hypotension (p<0.05). There were no significant changes of PO2, PCO2, HCO3 , base excess before, during and after induced hypotension in both group. CONCLUSION: Propofol is also an effective hypotensive agent comparable to isoflurane.

The Effects of Sodium Nitroprusside on Platelet Aggregation Function during Intracranial Aneurysm Operation under Isoflurane Anesthesia / 대한마취과학회지

BACKGROUND: The intravenous infusion of sodium nitroprusside is widely used as a means of producing deliberate hypotension in a variety of clinical situations. However, sodium nitroprusside reported to inhibit platelet aggregation. So we studied the effects of sodium nitroprusside on platelet function in patients undergoing intracranial aneurysm surgery with isoflurane anesthesia. METHODS: Platelet rich plasma from the patients receiving sodium nitroprusside was studied for aggregation in response to adenosine diphosphate, epinephrine and collagen. Maximum aggregation rate and maximum aggregation time were evaluated from the samples collected at pre-sodium nitroprusside infusion, 30min and 90min after sodium nitroprusside infusion, respectively. At the same time, bleeding time was measured. RESULTS: The mean maximum aggregation rate of adenosine diphosphate, epinephrine and collagen at pre-sodium nitroprusside infusion decreased significantly 30min and 90min after sodium nitroprusside infusion, respectively(P<0.05). But the maximum aggregation time showed no significant change. Prolongation of bleeding time was not observed after sodium nitroprusside infusion. Correlation between the total sodium nitroprusside dose delivered and the maximum aggregation rate of adenosine diphosphate, epinephrine and collagen were significant (r=0.797(P<0.05), r=0.732 (P<0.05) and r=0.737(P<0.05)). CONCLUSIONS: In situation where sodium nitroprusside is administered for deliberate hypotensive anesthesia during intracranial aneurysm operation, the platelet aggregation was inhibited by sodium nitroprusside. However, bleeding time was not prolonged.