Continuous Epidural Clonidine for Analgesia after Cesarean Section / 대한마취과학회지

BACKGROUND: Clonidine, an 2-adrenergic agonist, shows the analgesic effect and potentiates the analgesic effect of opioid. However, when it is injected with bolus technique, it reveals the short duration of inadequate analgesia and induces hypotension, bradycardia or sedation. We examined the analgesic and side effects of clonidine administered by continuous epidural infusion over 24 hrs, following epidural morphine injection. METHODS: Sixty parturients, scheduled for elective cesarean section under epidural anesthesia were randomly allocated into three groups. They received an infusion of saline alone (group 1, n= 20), clonidine 20 g/hr (group 2, n= 20), or 40 g/hr (group 3, n= 20) respectively, following epidural morphine 3 mg injection at the end of operation. The total doses and number of request for supplemental analgesic, blood pressure, heart rate, and degree of sedation were measured during 24 hrs. RESULTS: There were significant differences in pain relief between clonidine groups and group 1. The total doses and number of patient's request for supplemental analgesic in clonidine groups, compared to group 1 were significantly decreased (p<0.05), but no significant differences between the two clonidine groups. The diastolic pressure of group 3 was significantly lower than that of group 1 over 24 hrs, and that of group 2 at 18 hr, 24 hr (p<0.05). However, there was no severe hypotension, bradycardia or sedation in the three groups. CONCLUSION: Clonidine administered by continuous epidural infusion over 24 hrs enhances the analgesic effect of epidural morphine, and the infusion of clonidine with 20 g/hr rather than 40 g/hr shows minimal changes of blood pressure. Therefore, administration of epidural clonidine (20 g/hr) following epidural morphine may be considered as a regimen for pain management after cesarean section.

Pulmonary Function Changes during Spinal Anesthesia - Bupivacaine vs. Tetracaine - / 대한마취과학회지

BACKGROUND: Although degree of motor blockade during high thoracic spinal anesthesia is difficult to determine, pulmonary function may reflect the level of motor blockade. So we checked pulmonary function during spinal anesthesia with two different local anesthetic agents. METHODS: 50 patients, ASA PS 1-2, were randomly divided into two groups. After basal pulmonary function test (FVC: forced vital capacity, FEV1: forced expiratory volume in one second, PEFR: peak expiratory flow rate, PEP: peak expiratory pressure, PIP: peak inspiratory pressure.), the patients received spinal anesthesia with either 0.5% hyperbaric bupivacaine or 0.5% hyperbaric tetracaine. Thirty minutes after injection, level of sensory blockade was checked by pinprick test and pulmonary function test was performed. RESULTS: Almost all the values of pulmonary function reduced after spinal anesthesia, but the degrees of reduction were not differ in two groups except PEP, which reduced more profoundly in tetracaine group than bupivacaine group. CONCLUSIONS: It is more desirable that we use bupivacaine rather than tetracaine as spinal anesthetic agent in the patient with poor pulmonary function.

The Effects on Hemodynamic Stability by Combined Use of Conventional Ultrafiltration and Modified Ultrafiltration in Paediatric Cardiac Surgery / 대한마취과학회지

BACKGROUND: Ultrafiltration, used in pediatric cardiac operations to remove excessive body water, can be separated into conventional and modified techniques according to the connection with the bypass circuit and the time of starting ultrafiltration. Ultrafiltration provides more precise hemodynamic and fluid management immediately after CPB (cardiopulmonary bypass), especially in the pediatric patient. The mechanism by which blood pressure improves remains uncertain. The purpose of this study was to compare the efficacy of ultrafiltration for hemodynamics and reduce the blood consumption amounts in paediatric open heart operations. METHODS: Fourty children undergoing surgical correction of VSD (ventricular septal defect) or ASD (atrial septal defect) were randomly assigned to a ultrafiltration or control group. Conventional ultrafiltration was performed with a polysurphone hemofilter during rewarming of CPB. Modified ultrafiltration carried out in the first 10 to 15 minutes immediately after bypass. In all patients, moderate hypothermic CPB, in the range of 20~25 degrees C body temperature, was performed with nonpulsating flow. RESULTS: Demographic data as well as data from CPB did not differ among the groups. In the ultrafiltration group, significant reductions of the amount of blood transfusion significant increases in systolic pressure and hematocrit were noted in the ultrafiltration group. We have been impressed with what appears to be a marked improvement in hemodynamic status in the modified ultrafiltration process during the first few minutes. CONCLUSIONS: Ultrafiltration has been employed successfully in our hospital, and this study demonstrates that ultrafiltration may help to control water balance, concentration of blood, increase systemic arterial pressure and reduces intraoperative blood transfusion.

The Pulmonary Hemodynamic Effects of Nitric Oxide Inhalation on Hypoxic Pulmonary Vasoconstriction / 대한마취과학회지

BACKGROUND: Nitric Oxide (NO) has been discovered to be an important endothelium-derived relaxing factor. The exogenous inhaled NO may diffuse from the alveoli to pulmonary vascular smooth muscle and produce pulmonary vasodilation, but any NO that diffuses into blood will be inactivated before it can produce systemic effects. To examine the effects of NO on pulmonary and systemic hemodynamics, NO was inhaled by experimental dogs in an attempt to reduce the increase in pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) induced by hypoxia in dogs. METHODS: Eight mongrel dogs were studied while inhaling 1)50% O2 (baseline), 2)12% O2 in N2 (hypoxia), 3)followed by the same hypoxic gas mixture of O2 and N2 containing 20, 40 and 80 ppm of NO, respectively. RESULTS: Breathing at FIO2 0.12 nearly doubled the pulmonary vascular resistance from 173 56dyn sec cm-5 to 407 139dyn sec cm-5 and significantly increased the mean pulmonary artery pressure from 16 3mmHg to 22 4mmHg. After adding 20~80 ppm NO to the inspired gas while maintaining the FIO2 at 0.12, the mean pulmonary artery pressure decreased (p<0.05) to the level when breathing oxygen at FIO2 0.5 while the PaO2 and PaCO2 were unchanged. The pulmonary vascular resistance decreased significantly and the right ventricular stroke work index returned to a level similar to breathing at FIO2 0.5 by addition of NO into the breathing circuit. Pulmonary hypertension resumed within 3~5 minutes of ceasing NO inhalation. In none of our studies did inhaling NO produce systemic hypotension and elevate methemoglobin levels. CONCLUSIONS: Inhalation of 20~80 ppm NO selectively induced pulmonary vasodilation and reversed hypoxic pulmonary vasoconstriction without causing systemic vasodilation and bronchodilation. Methemoglobin and NO2 were within normal limit during the study.

Anesthetic Management of Carotid Endarterectomy under EEG and SEP Monitoring / 대한마취과학회지

BACKGROUND: Carotid endarterectomy is a very high risk operation, combined with high incidence of stroke and myocardial infarction. We experienced 36 cases of carotid endarterectomies during the last two years. We reviewed these cases with anesthetic management and neurologic monitoring. METHODS: All of the operations were performed under general anesthesia. 33 cases were monitored by EEG and SEP. We maintained cerebral perfusion during cross-clamping and shunt by normothermia, normocarbia and mild hypertension. RESULTS: 33% of the patients had severe coronary artery stenosis and 41% had severe contralateral carotid artery stenosis preoperatively. During the operation, 10 patients showed transient EEG changes without SEP change or neurologic sequele. The major postoperative complication was myocarial infarction in one patient. There were 3 cases of postoperative cerebral infarction in radiologic findings. One case occurred after myocardial infarction and the other two cases showed no clinical evidence of neurologic deficit. CONCLUSIONS: In anesthetic management of carotid endarterectomy patients, maintaining cerebral perfusion, preventing perioperative myocardial infarction are important and monitoring neurologic function with EEG and SEP should be considered to prevent neurologic deficits.