A Double Blind Randomized, Placebo Controlled Study Evaluating the Effect of Ondansetron in Reducing Spinal- Induced Hypotension Using Low Dose Bupivacaine in Parturients Undergoing Caesarean Section.

Background: Spinal induced hypotension is the most common intraoperative complication after spinal anesthesia during cesarean delivery. Various adjuvant techniques/drugs had been used in the past to minimize the haemodynamic effects of spinal anaesthesia. Five-hydroxytriptamine (5-HT), a serotonergic receptor, may be an important factor associated with inducing the Bezold Jarish reflex (BJR) that may lead to the bradycardia and hypotension in the setting of decreased blood volume. Some animal and human studies further supported that BJR can be decreased by 5-HT3 antagonists. Aim: The present study work is to assess the effects of Inj. Ondansetron (a selective 5‑HT3 receptor antagonist) in preventing spinal induced hypotension in patient undergoing elective Caesarean section. Methods: Sixty parturients scheduled for elective caesarean section were randomly allocated into two groups. Group O (30 patients): Inj. Ondansetron (4 mg IV) diluted in 10 mL of normal saline, administered 5 minutes before spinal anaesthesia and Group N (30 patients): Normal saline 10 mL given 5 minutes before spinal anaesthesia. We observed the haemodynamic parameters as our primary outcome and neonatal outcome in terms of APGAR scoring as secondary outcome. Results: Both the groups were comparable in terms of demographic characteristics. The decrease in mean arterial pressure in Group O was significantly lesser than Group N from 6 min until 30 min. The requirement of vasopressor (Inj. Phenylephrine) was significantly less in Group O than Group N (P = 0.015). Neonatal outcome in terms of APGAR Score and gas analysis were comparable between the groups. Conclusion: Inj. Ondansetron (4 mg IV), given intravenously 5 min before subarachnoid block reduced hypotension and vasopressor use in parturients undergoing elective caesarean section.

Perioperative Stroke in the Brain and Spinal Cord Following an Induced Hypotension

A 49-year-old woman presented with stupor and paraplegia following an induced hypotension. The temporal relationship to the induced hypotension and the absence of a clear embolic source on diagnostic tests support a causal association between the hypotensive episode and the ischemic infarct. However, despite the association, a cause-and-effect relationship could not be automatically inferred.

Effects of Sildenafil Citrate on Sodium Nitroprusside and Nitroglycerin-Induced Hypotension in Dogs / 대한마취과학회지

BACKGROUND: Nitrovasodilators are known to induce hypotension through activating nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway. By inhibiting the breakdown of cGMP, sildenafil citrate may augment the nitrovasodilator-induced hypotension. The present study was aimed to investigate whether sildenafil would reduce the dose of nitrovasodilators needed to induce the hypotension. METHODS: Ten mongrel dogs were acutely instrumented with a femoral artery catheter and a pulmonary artery catheter. They were intravenously given sodium nitroprusside (SNP; 1-16ng/kg/min) or nitroglycerin (NTG; 2 - 32ng/kg/min) to induce hypotension. The study was composed of two occasions in each animal: one with sildenafil pretreatment (1 mg/kg IV followed by 0.3 mg/kg/h) and the other without to serve as control, one week apart. Hemodynamic parameters were continuously monitored. Plasma cGMP concentrations were measured by radioimmunoassay. RESULTS: Both SNP and NTG produced dose-dependent reductions in mean arterial pressure (MAP) without affecting the heart rate in both the control and sildenafil groups. Systemic vascular resistance index (SVRI) and mean pulmonary arterial pressure were also decreased. However, SNP caused a greater reduction of MAP and SVRI in the sildenafil group than in the control group; whereas, NTP caused similar reductions in both groups. Neither SNP nor NTG altered the plasma cGMP concentrations. Sildenafil increased the plasma cGMP concentration, which was further increased by SNP, but not by NTG. CONCLUSIONS: These results indicate that sildenafil may reduce the dose of SNP, but not that of NTG needed to produce hypotension in the dog. The potentiation of SNP-induced hypotension by sildenafil may be related to an augmented cGMP effect.

Difference of Jugular Bulb Oxygen Saturation under Propofol, Enflurane and Isoflurane Anesthesia with Hydralazine-induced Deliberate Hypotension / 대한마취과학회지

BACKGROUND: Hydralazine produces cerebral vasodilation, which could appear differently according to which kind of anesthetics was used. SjO2, CBF and AJDO2 have been studied during general anesthesia with enflurane, isoflurane or propofol in 42 patients undergoing spinal surgery. METHODS: Forty-two healthy adult patients were divided into Group P (Propofol-N2O, n = 15), Group E (Enflurane-N2O, n = 15) and Group I (Isoflurane-N2O, n = 12). During the course of the study, the anesthetic concentration was constant. Induced hypotension was provided with hydralazine 20 mg in combination with a continuous infusion of esmolol within 50 - 100ng/kg/min. Arterial blood and jugular bulb blood were obtained and analyzed at normotensive and hypotensive period, respectively. SjO2, was compared within and between groups. RESULTS: SjO2 values of Group P were 66.2 +/- 7.7%, and 81.5 +/- 6.1%, those of Group E were 79.5 +/- 5.6%, and 78.9 +/- 4.9% and those of Group I were 82.0 +/- 6.2%, and 84.4 +/- 3.7% at normotension and hypotension, respectively (P < 0.05 between Group P and Group E, P < 0.05 between Group P and Group I, P < 0.05 within Group P). CONCLUSIONS: When the changes of CBF is assumed with that of SjO2, it may be concluded that CBF increased with hydralazine-induced hypotension in propofol-N2O anesthesia. It may be suggested that hydralazine reverses propofol induced cerebral vasoconstriction.

The Effect of Induced Hypotension on Intraoperative Blood Loss during Spinal Surgery / 대한마취과학회지

BACKGROUND: This study was performed to evaluate whether the degree of hypotension influences blood loss during spinal surgery. METHOD: Fifty patients undergoing only one level spinal fusion were assigned to one of three groups. In group 1 (n = 14), the systolic blood pressure (SBP) was maintained at 100 120 mmHg with enflurane. In groups 2 (n = 18) and 3 (n = 18), the SBP were maintained at 80 100 and 60 80 mmHg, respectively. Hydralazine and esmolol were used in the hypotensive groups. RESULTS: Blood losses during operation in groups 2 (554 +/- 287 ml) and 3 (456 +/- 162 ml) were significantly lower than in group 1 (1141 +/- 690 ml) (P < 0.05), although there was no significant difference between groups 2 and 3. The percentage of patients receiving transfusions during the operation in groups 1 and 2 were 57.1 and 5.6%, respectively. CONCLUSIONS: The results show that a moderate reduction in SBP (80 - 100 mmHg) reduces blood loss by more than half in comparison to a mild reduction in SBP (100 - 120 mmHg). However, a severe reduction in SBP (60 - 80 mmHg) does not increase the reduction in blood loss in comparison to moderate hypotension.

Comparison of Liver Function after Induced Hypotension between Enflurane and Isoflurane Anesthesia in Spinal Surgery / 대한마취과학회지

BACKGROUND: Induced hypotension reduces blood loss in the surgical field and provides better visibility, but may produce ischemic damage to the liver. The purpose of this study is to compare liver function after induced hypotension between general anesthesia with enflurane and isoflurane in spinal surgery. METHODS: Forty patients were randomly allocated to enflurane (group 1, n = 20) and isoflurane (group 2, n = 20) group. During operation, hypotension was induced with hydralazine to maintain systolic blood pressure between 60 to 80 mmHg in both groups. Preoperative and postoperative 1, 3, 5 and 7 days' serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvate transaminase (SGPT) and alkaline phosphatase (ALP) were evaluated. RESULTS: In group 1, SGOT levels increased significantly at postoperative 1, 3 days, and SGPT levels increased significantly at postoperative 3, 5, 7 days. In group 2, SGOT levels increased significantly at postoperative 1, 3, 5, 7 days, and SGPT levels increased significantly at postoperative 3, 5, 7 days, but there was no significant difference between the groups in SGOT and SGPT levels. ALP levels decreased at postoperative 1, 3, 5 days in group 1, and at postoperative 1, 3 days in group 2; however, there was no significant difference between the groups in ALP levels except in preoperative values. CONCLUSIONS: These results suggest that there is no difference in postoperative liver function between general anesthesia with enflurane and isoflurane in spinal surgery after induced hypotension.

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.

Effects of Induced Hypotension with Labetalol on Blood Loss and Blood Pressure in Maxillofacial Surgical Patients / 대한마취과학회지

BACKGROUND: The worst problem in anesthetic management of maxillofacial surgery is bleeding from bone cutting site. Induced hypotension reduces bleeding and minimizes the need for blood transfusion. This study was performed to evaluate the effects of induced hypotension with labetalol on blood loss and blood pressure in maxillofacial surgical patients. METHODS: Twenty-four adult patients, either sex, ASA physical status I or II, undergoing orthognathic surgery were randomly selected and divided into two groups; one group was administered 20 mg of labetalol and the other group was not. Anesthetic maintenance was consisted of O2-N2O-enflurane (2~2.5 vol%). Then 20 mg of labetalol was given intravenously at skin incision time in the labetalol group. Hemodynamic variables were recorded before induction of anesthesia, at the beginning of the labetalol infusion and at 10 min, 20 min, 30 min, 60 min and 90 min after the infusion. Blood loss determined by measuring the weight of the sponges and by measuring the volume of blood in suction-trap bottle. RESULTS: There was no significant difference in preoperative hemoglobin and postoperative hemoglobin between two groups. The amount of blood loss in the labetalol group (408 +/- 202 ml) was less than those in the control group (450 +/- 255 ml), but statistically not significant. The blood pressure was significantly decreased in the labetalol group than those of the control group at 20 minutes after the labetalol infusion. CONCLUSIONS: Labetalol is a useful agent for inducing hypotension. But 20 mg of labetalol was insufficient to decrease the blood loss. So I think the more amount of labetalol required to reduce the blood loss.

The Comparison of Propofol and Sodium Nitroprusside in Induced Hypotension undergoing Endoscopic Sinus Surgery / 대한마취과학회지

BACKGROUND: The general anesthesia for endoscopic sinus surgery (ESS) is associated with increase in intraoperative bleeding, which can interfere with optimal visualization through the endoscope, so we compared the effectiveness of propofol as induced hypotensive agent with sodium nitroprusside (SNP) in ESS. METHODS: Twenty patients undergoing ESS under general anesthesia were allogated randomly to recieve thiopental sodium induction with enflurane maintenance and induced hypotension by SNP (SNP group), or propofol induction and propofol maintenance (propofol group). The two groups were recieved nalbuphine, vecuronium, nitrous oxide and oxygen for anesthesia. The hypotensive effects, hemodynamic changes were evaluated with mean arterial pressure (MAP), heart rate (HR), hematocrit of preoperative, intraoperative and postoperative period and estimated blood loss (EBL). RESULTS: Mean arterial pressure was significantly decreased during hypotensive anesthesia (p<0.05), but any other parameters (HR, EBL and hematocrit change) were not significantly different in two groups. CONCLUSION: Propofol has an effectiveness of hypotensive agent as SNP; and make endoscopic sinus surgery technically easier and safer by improving endoscopic visualization of the surgical field with less blood loss.

Anesthetic Management of Giant Intracranial Aneurysm / 대한마취과학회지

A 50 year-old woman was scheduled for clipping of giant middle cerebral artery (MCA) aneurysm. Preoperative four-vessel angiography and computed tomography scan revealed a giant aneurysm (3.5x3.3x3.5 cm) at bifurcation of right MCA. Induced hypotension and brain protection using sodium nitroprusside (SNP) and thiopental loading were planned to prevent cerebral damage during the operation. Before induction, esmolol, lidocaine and vecuronium were administered. Mask ventilation with isoflurane in N2O and O2 was performed over 5 minutes and then tracheal intubation was done. Anesthesia was maintained by isoflurane+N2O+O2 with pancuronium. Electrocardiography, pulse oxymetry, capnography, central venous pressure, evoked potential and invasive arterial blood pressure were monitored. She was hyperventilated intraoperatively with a PaCO2 around 30 mmHg. Perioperative hypotension was achieved with infusion of SNP (0.3~1.0 microg/kg/min). During the actual aneurysm surgery, mean arterial pressure was lowered to approximately 50 mmHg. Adjuvant drugs such as methylprednisolone, mannitol and furosemide to reduce intracranial pressure were also administered. This technique established good brain conditions during clipping of the aneurysm. A thiopental loading (4 mg/kg) was supplied while the aneurysm was approached. Satisfactory and well-controlled hypotension was obtained after thiopental and SNP. Postoperatively, the patient was transferred to the intensive care unit.

The Comparison between the Postoperative Predicted and Actual Hematocrit / 대한마취과학회지

BACKGREOUND: Several formulas for estimating allowable pre-transfusion blood loss were used to reduce unnecessary intraoperative blood replacement. The postoperative predicted hematocrit computed by formula was compared with the actual hematocrit and was tested which formula was more accurate in spine surgery. METHOD: Total blood volume was estimated in spine surgery of 34 patients. The target hematocrit (Hct) was suggested on 30% and the allowable blood loss was computed using the formula 1 and 2. For each patients, simultaneous measurement of blood loss and Hct was obtained at the end of operation. The postoperative predicted Hct by the formula 1 and 2 was calculated and compared with the actual Hct, and the difference between the formula 1 and 2 was evaluated. Allowable blood loss=Estimated blood volume (Initial Hct Target Hct)/Initial Hct ... Formula (1) Allowable blood loss=Estimated blood volume (Initial Hct Target Hct)/Average Hct ... Formula (2) RESULTS: 1) The preoperative Hct was 40.7 3.9%. The postoperative predicted Hct by the formula 1 and 2 were 34.3 4.6 and 34.9 4.3% respectively. The postoperative actual Hct was 30.1 4.6%.2) The difference between the predicted Hct by the formula 1 and the actual Hct was 4.2% (P<0.05). The difference between the predicted Hct by the formula 2 and the actual Hct was 4.8% (P<0.05). The difference between the predicted Hct by the formula 1 and 2 was 0.6% (P<0.05). It was thought that the predicted Hct by the formula 1 was more closer to the actual Hct. CONCLUSIONS: The predicted Hct by both formulas is underestimated when the results compare with the actual Hct. But the predicted Hct by the formula 1 provides a closer results to the actual Hct than the predicted Hct by the formula 2.

Comparison of Post-operative Liver Function after Induced Hypotention between Thoracic Epidural Bldegrees Ckade and Esmolol / 대한마취과학회지

BACKGROUND: Induced hypotension reduces blood loss in the surgical field and provies better visibility. May methods have been used for induced hypotension. Recently Esmolol is favored in induced hypotension because of its short action of sympathetic beta-1 receptor antagonist and easy to control. Thoracic epidural bldegrees Ck can provide cadiovascular stability in induced hypotension. The purpose of the study is to compare postoperative liver function after induced hypotension between thoracic epidural bldegrees Ckade and esmolol combined with general anesthesia with isoflulane. METHOD: Fourty patients scheduled for spinal posterior fusion under general anesthesia were randomly divided into two groups. In thoracic epidural bldegrees Ckade group(Group I, 20 patients), 8~10 ml of 2% liddegrees Caine was injected into the epidural catheter ldegrees Cated in T6~7 interspace in a bolus. In Esmolol group(Group II, 20 patients) received 0.5 mg/kg as loading dose and 50~150 microgram/kg/min continuously. We measured preoperative and postoperative 1, 3, 5, 7 day's serum glutamic-oxaloacetic transaminase(SGOT), serum glutamic-pyruvate transaminase(SGPT) and alkaline phosphatase(ALP). RESULT: In the thoracic epidural bldegrees Ckade group, there was statistically significant increase of SGOT level above normal range on postoperative 1 day, which decreased on postoperative 3 and 5 day(p<0.05). But it was within normal range on postoperative 7 day. SGPT was increased within normal range. Similarly, in the esmolol group, there was statistically significant increase of SGOT level above normal range on postoperative 1 day, which decreased on postoperative 3 and 5 day(p<0.05). But it was within normal range on postoperative 7 day. SGPT was increased within normal range. The level of ALP was increased within normal range in both groups. There was no statistically significant difference in liver function between two groups. CONCLUSION: We consider that postoperative liver function is little influenced with induced hypotension by thoracic epidural bldegrees Ckade and esmolol combined with general anesthesia with isoflurane.

Induced Hypotension Using Esmolol in Spinal Surgery / 대한마취과학회지

Background: Esmolol as a drug for induced hypotension can, not only avoid many drawbacks of nitroprusside, but reduce the amount of intraoperative bleeding and make better operative field. This study was performed to evalute cardiovascular changes during esmolol-induced controlled hypotension. Methods: Induced hypotension using esmolol was applied to 18 adult patients receiving spinal surgery under the diagnosis of spinal stenosis or scoliosis. After prehydraion of 2,000 ml of crystalloid solution, 0.5 mg/kg esmolol was used as loading dose once, twice or three times until mean blood pressure (MBP) fell below 70 mmHg, followed by continuous infusion (50~300 microg/kg/min) of esmolol. MBP and heart rate (HR) were measured before, 5, 10, 15, 30, 60 and 90 min after esmolol administration, and 5, 10 and 15 minutes after discontinuation of esmolol. In 8 patients, cardiac output (CO) and mixed venous oxygen tension and saturation were measured before, during and after esmolol use. Results: MBP was decreased from 91+/-12 mmHg to 67+/-7 mmHg after 15 min (P<0.05). HR(BPM) was decreased from 76+/-17 to about 60 after 15 min (P<0.05). CO was decreased about 30% during induced hypotension but recoverd to initial level 15 min after esmolol discontinuation. While oxygen transport was reduced significantly during induced hypotension (P<0.05), oxygen consumption was maintained all the time. Conclusion: With the use of esmolol, stable hypotension could be achieved. Although oxygen transport decreased possibly due to reduction of CO, but oxygen consumption was maintained.

Comparison of the Blood Loss during and after Spinal Surgery under Hypotensive Anesthesia and Effects of Furosemide on the Urine Output during Hypotensive Anesthesia for Spinal Surgery / 대한마취과학회지

BACKGROUND: The induced hypotensive anesthesia may produce serious complications related to central nervous system, heart, liver, kidney and eyes. In this study, the blood loss during and after operation were compared to evaluate the delayed effect of hypotension on postoperative bleeding and also, the urine output was measured in control group and furosemide treated group, to investigate the effect of furosemide on the protection of kidney function. METHODS: Forty patients undergoing spinal surgery were evaluated and the hypotension was induced by the combination of hydralazine, esmolol and propranolol under enflurane anesthesia. During hypotensive anesthesia, the systolic arterial blood pressure was maintained between 65 to 75 mmHg. I compared the arterial blood gas analysis, plasma protein, albumin and calcium level, blood urea nitrogen (BUN), creatinine and complete blood count (CBC) before, durng and after hypotensive anesthesia. And also, the volume of blood loss and the units of transfused blood were measured intraoperatively and postoperatively. To investigate the effect of furosemide on the protection of kidney function, patients were randomly divided to contol group (n=20) and furosemide group (n=20). In furosemide goup, 0.1 mg/kg was administered intravenously and the urine output was measured during and after hypotensive anesthesia in both groups. RESULTS: The systolic arterial blood pressure during hypotensive anesthesia was maintained between 65 to 75 mmHg as planned in all forty patients. The average blood loss during and after operation were 769+/-541 and 786+/-397 ml, respectively and the average total blood loss was 1555+/-784 ml. The average units of transfused packed red cell during and after operation were 2.6+/-0.8 and 1.9+/-0.4 units, respectively, and the average total transfused units were 2.3+/-0.8 units. In both control and furosemide treated groups, all forty patients showed oliguria during first two hours after starting hypotensive anesthesia but urine outputs were recovered after the end of hypotensive anesthesia in both groups. During and after hypotensive anesthesia, pH was slightly but significantly decreased. Plasma protein, albumin, calcium and BUN were decreased during and after hypotensive anesthesia compared with before hypotensive anesthesia values. During and after hypotensive anesthesia, platelet count was decreased significantly but white cell count was increased. Severe oliguria was noted during hypotensive anesthesia in both groups and no serious complication related to hypotensive anesthesia was found. CONCLUSIONS: In this study, the volume of blood loss after anesthesia was almost same as that during anesthesia. And the administration of furosemide 0.1 mg/kg did not prevent oliguria during hypotensive anesthesia.

Comparison of Sodium Nitroprusside and Esmolol Induced Hypotension for Total Hip Arthroplasty / 대한마취과학회지

BACKGROUND: Esmolol is a short acting sympathetic beta receptor antagonist, and it was successfully applied to induced hypotension. Esmolol lowers blood pressure by decreasing cardiac output, and does not cause vasodilation. This property of esmolol may help to decrease bleeding during induced hypotension. In this study, we tried to elucidate the effect of esmolol on induced hypotension for total hip arthroplasty. METHOD: Twenty patients receiving total hip arthroplasty were randomly divided to two groups. Esmolol group (10 patients) received esmolol as a hypotensive agent, and sodium nitroprusside (SNP) group (10 patients) received SNP as a hypotensive agent. We measured arterial blood gas analysis, vital sign, amounts of bleeding, amounts of transfusion and administered fluid, and various laboratory findings. RESULTS: Induced hypotension was successfully performed in either esmolol and SNP group. Heart rate increased by SNP, and decreased by esmolol. There were no statistically significant differences between the two groups in amounts of bleeding, amounts of transfusion or administered fluid, and laboratory findings. Arterial oxygen tension was relatively constant in esmolol group, but decreased in SNP group. CONCLUSION: Esmolol can be used as a single hypotensive agent during induced hypotension without significant side effects during total hip arthroplasty.

Effects of Sodium Nitroprusside and Nitroglycerin on the Venous Capacitance during Induced Hypotension in Halothane Anesthetized Dogs / 대한마취과학회지

BACKGROUND: Since a change in venous capacitance significantly alters venous return and thus affects cardiac output, it is important to know the effects of vasodilators on venous capacitance. The purpose of this study was to examine the effects of sodium nitroprusside and nitroglycerin on venous capacitance during induced hypotension in halothane anesthetized dogs. METHODS: Fourteen mongrel dogs(SNP group: 7, NTG group: 7), weighing 10~15 kg, were anesthetized with N2O 1.5L/min-O2 1.5L/min-halothane 0.5vol%. Each dog received only one drug. In dogs anesthetized with N2O-O2-halothane, mean arterial pressure(MAP) was decreased by 15%(mild hypotension) and 30%(deep hypotension) of control value by sodium nitroprusside(SNP) and nitroglycerin (NTG), respectively. Venous capacitance was assessed before and during induced hypotension by measuring mean circulatory filling pressure(MCFP). MCFP was measured after arresting the circulation by tightening of superior vena cava and inferior vena cava snares simultaneously. RESULTS: As compared with MCFP before induced hypotension, MCFP was significantly decreased by SNP at deep hypotension and NTG at mild hypotension and deep hypotension. As compared with MCFP at mild hypotension, MCFP at deep hypotension was significantly decreased by NTG and SNP, respectively. CONCLUSIONS: These results suggest that NTG has potent venodilating effect at mild and deep induced hypotension, whereas SNP has venodilating effect only at deep induced hypotension.

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.

Induced Hypotension And Bradycardia During General Anesthesia For Coronaray Artery Bypass Graft Without Cardiopulmonary Bypass: A case report / 대한마취과학회지

Coronary artery bypass grafting(CABG) without cardiopulmonary bypass is now an accepted technique of myocardial revasculization in terms of preventive method from various complications of cardiopulmonary bypass. Despite danger of myocardial ischemia, induced hypotension with bradycardia are sometimes necessary for the convenience of operative approach to beating heart. We report a case of induced hypotension with bradycardia during general anesthesia for CABG without cardiopulmonary bypass. After induction and maintenance of balanced anesthesia with fentanyl-midazolam-isofluranepiperocuronium for the 68 kg, 55 years old male stable angina patient, we induced controlled hypotension(systolic blood pressure: 70~80 mmHg) and bradycardia(heart rate: 50~60/min.) by bolus injections of verapamil 5 mg and esmolol 30 mg followed by continuous infusion of esmolol 0.1~0.3 mg/kg/min. during 50 minutes of main graft implantations without bypass. Any significant ischemic changes on EKG were not detected during induced hypotension and bradycardia. Patient was recovered without any signs of myocardial ischemia postoperativery and discharged 8 days after operation.

The Effect of Esmolol on Changes of Heart Rate during Induced Hypotension with Sodium Nitroprusside / 대한마취과학회지

BACKGROUND: The goal of this study was to demonstrate the effect of esmolol to prevent reflex tachycardia occurred during sodium nitroprusside(SNP) induced hypotension. METHODS: Thirty patients were randomly assigned to the SNP group(n=15) received continuous infusion of SNP at 2.72+/-0.56 mcg/kg/min or combined SNP and esmolol(SNP-ESM) group(n=l5) received combined continuous infusion of SNP at 1.54+/-0.34 mcg/kg/min and esmolol at 200 mcg/kg/min for 1 hour to maintain a 20~25% reduction of mean arterial pressure(MAP) from baseline. Heart rate(HR) and MAP were measured at baseline, during hypotensive period(5, 10, 20, 30, 60 min) and after hypotensive period(70, 80, 90,1 20 min). RESULTS: SNP-induced hypotension resulted in significant(P<0.001) increases in heart rate during hypotensive period and MAP after the end of SNP infusion. However, infusion of SNP-ESM resulted in significant(p<0.05) reduction in heart rate and SNP requirement during hypotensive period, and rebound hypertension was not observed after the end of induced hypotension. CONCLUSIONS: SNP-ESM infusion is a safe and effective pharmacologic means and provides several advantages over single SNP that include reduction in SNP requirement, no reflex tachycardia during induced hypotension and no rebound hypertension following hypotensive period.