Transesophageal echocardiographic monitoring for transcatheter closure of atrial septal defect

BACKGROUND AND PURPOSE

Transcatheter closure of atrial septal defect (ASD) is generally performed under fluoroscopy alone. Recently, we have used transesophageal echocardiography (TEE) monitoring as an aid in performing this procedure. The purpose of this study was to evaluate the efficacy and complications associated with this use of TEE.

METHODS

Transcatheter closure of ASD was accomplished under TEE guidance simultaneously with fluoroscopic imaging in 11 patients aged 3 to 33 years (weight, 15.4-62.9 kg). TEE was successfully performed in all patients after endotracheal general anesthesia. The ASDs were reexamined before catheterization. The appropriate placement of the occluder device was evaluated.

RESULTS

Seven cases were uneventful with successful ASD occluder implantation, but one failed because of a large ASD (24.7 mm). In three cases, transcatheter closure was aborted after TEE examination, one with a large ASD (27.05 mm), one with an ASD that was too small, and one with multiple fenestrated ASDs.

CONCLUSIONS

Routine TEE monitoring for transcatheter closure of ASDs is effective for evaluation of ASD before implantation of an occluder, to ensure the proper seating of the occluder after the defect occlusion is complete.

Comparison of invasive and non-invasive measurement of spontaneous baroreflex during anesthesia

BACKGROUND

Many works have shown that beat-to-beat variations in systolic arterial pressure (SAP) could be used for the assessment of cardiac baroreflex function. The purpose of this study was to evaluate whether Finapres, a non-invasive device to measure systolic arterial pressure, could serve as an acceptable alternative to intra-arterial catheterization for assessing the spontaneous baroreflex during anesthesia.

METHODS

Thirty ASA class I patients scheduled for surgical hepatic and gastric tumor excisions were enrolled in this study. Spontaneous baroreflex sensitivity (SBR) during anesthesia was calculated by sequence analysis of beat-to-beat variations in systolic arterial pressure and R-R intervals. Data obtained from Finapres were compared with those from standard intra-arterial catheterization technique.

RESULTS

SBR values determined by non-invasive and invasive blood pressure measurement technique were precisely correlated (r = 0.96) and the mean difference was about 0.22 ms/mmHg (12.5%). However, the individual data might differ by -0.52 to +0.96 ms/mmHg (-35% to +60%).

CONCLUSIONS

Finapres may trace the changes of SBR during anesthesia and provides similar results as does invasive method but individual variation exists.

Intravenous pretreatment with magnolol protects myocardium against stunning

Magnolol, an antioxidant, has been reported to possess various protective effects on the cardiovascular system. However, its effect on myocardial stunning has not been elucidated. The purpose of this study was to investigate the antistunning effect of magnolol by evaluating the recovery of regional myocardial function after 10-minute coronary artery occlusion in anesthetized, open-chest rabbits. There was no significant hemodynamic change after intravenous infusion of magnolol. Systolic wall thickening fraction (WThF) measured with an epicardial Doppler sensor in animals pretreated with normal saline and vehicle solution remained significantly depressed (60 +/- 7% and 77 +/- 4% of baseline WThF, respectively) 3 hours after coronary artery reperfusion (CAR). Pretreatment with magnolol (10(-7) and 10(-6) g/kg, intravenous infusion) significantly enhanced the recovery of systolic wall thickening fraction (98 +/- 1 and 99 +/- 1% of baseline WThF, respectively) 60 minutes after CAR. This study demonstrated that intravenous pretreatment with magnolol protected myocardium against stunning.

Prophylactic intravenous ondansetron reduces the incidence of intrathecal morphine-induced pruritus in patients undergoing cesarean delivery

Pruritus is a common side effect of intrathecal morphine injection for postoperative pain control. Its incidence is especially high in patients undergoing cesarean delivery. We investigated the effectiveness of ondansetron in preventing intrathecal morphine-induced pruritus in such patients. We included 60 consecutive nonbreastfeeding women who were scheduled for elective cesarean delivery. After the administration of spinal anesthesia with bupivacaine and intrathecal morphine 0.15 mg injection, the patients were randomly divided into three groups. Group 1 received placebo (normal saline) IV injection, Group 2 diphenhydramine 30 mg IV injection, and Group 3 ondansetron 0.1 mg/kg IV injection. The incidence of pruritus was significantly lower in the ondansetron group (25%) when compared with that in the placebo group (85%) and in the diphenhydramine group (80%) (both P < 0.05). The postoperative pain score and time to flatus passage were not significantly different among the three groups. There were no headache or extrapyramidal signs associated with ondansetron use. In conclusion, ondansetron prophylaxis significantly reduced the incidence of intrathecal morphine-induced pruritus in patients undergoing cesarean delivery.

IMPLICATIONS

Ondansetron prophylaxis significantly decreases the incidence of pruritus, a common side effect of intrathecal morphine used to treat postcesarean delivery pain.

Effects of epidural fentanyl on labor pain during the early period of the first stage of induced labor in nulliparous women

BACKGROUND AND PURPOSE

It is generally accepted that epidural injection with local anesthetics and narcotics administered when the cervix has dilated to a diameter exceeding 4 cm can adequately control labor pain. However, many nulliparous women still suffer from labor pain for a few hours prior to the administration of epidural analgesia. This study examined the effectiveness of relief of labor pain obtained by injection of narcotics epidurally once the labor pain begins and the subject requests analgesia.

METHODS

Subjects scheduled for induced labour were divided into three groups: Group A (n = 60) received 5 x 10(-4)% fentanyl (10-20 mL) administered epidurally to relieve early first-stage labor pain. Group B (n = 60) received no analgesic in the early first stage of labor. For groups A and B, when cervical dilatation exceeded 4 cm, 10 to 15 mL of 5 x 10(-2)% bupivacaine and 2 x 10(-4)% fentanyl were injected epidurally and a continuous low dosage was maintained until full dilatation of the cervix resulted. Group C (n = 198) received no analgesic during the entire labor course.

RESULTS

There were no significant differences in the duration of the early period of the first stage of labor, the duration of the late period of the first stage, the duration of the second stage, the Apgar score, or the arterial blood gas of neonates among the three groups. However, group C had a significantly higher cesarean section rate (28.8%) than group A (16.7%) or group B (15%). Pain scores assessed with the Visual Analog Scale (VAS) throughout the entire labor course, were lower in group A than in group B; particularly during the early period of the first stage. The VAS scores in both groups A and B were significantly lower than those in group C during the late period of the first stage of labor.

CONCLUSIONS

The results indicate that once labor pain begins and the subject requests analgesia, epidural injection with fentanyl alone can relieve labor pain during the early period of the first stage. The analgesia does not cause adverse effects to the mothers or neonates. In addition, the labor course and the method of delivery are not affected.

Effect of magnolol on coronary vascular resistance in rabbits: measurement with pulsed Doppler velocimetry

BACKGROUND AND PURPOSE

Magnolol is an active component purified from Magnolia officinalis that has been reported to protect the myocardium against infarction and reperfusion injury. The purpose of this study was to investigate the effect of magnolol on the coronary circulation and to determine whether a change in coronary vascular resistance could be the mechanism underlying its myocardial protective effect.

METHODS

Male New Zealand white rabbits were anesthetized. A 3-mm suction-type pulsed Doppler velocimetry probe was applied to the proximal part of the left anterior descending coronary artery after median sternotomy. The 39 rabbits received intravenous injection of either vehicle (n = 5), magnolol (10(-6) g/kg, n = 6; 10(-5) g/kg, n = 5; 10(-4) g/kg, n = 5), or nitroglycerin (10(-5) g/kg, n = 6; 10(-4) g/kg, n = 6; 10(-3) g/kg, n = 6). The effects of magnolol and nitroglycerin on coronary vascular resistance were compared.

RESULTS

Magnolol did not change blood pressure or coronary blood flow velocity. However, at a dose of 10(-4) g/kg, it decreased coronary vascular resistance significantly more than vehicle (88 +/- 1% vs 95 +/- 1% of baseline coronary vascular resistance, p < 0.001). Nitroglycerin increased coronary blood flow velocity and decreased coronary vascular resistance in a dose-dependent manner (p < 0.01).

CONCLUSIONS

Magnolol reduced coronary vascular resistance in anesthetized, open-chest rabbits only at a high concentration. Its effect was modest compared with that of nitroglycerin. Since magnolol protects the myocardium at relatively low doses, coronary vasodilatation is unlikely to be the underlying mechanism responsible for its myocardial protective effects.

Spinal anesthesia in MELAS syndrome: a case with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes

MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) is one of the classic mitochondrial encephalomyopathies with variable clinical presentation and multisystem involvement. Enhanced sensitivity to neuromuscular blockade or anesthetic agents and susceptibility to malignant hyperthermia in these patients have ever been reported, all of which complicate the management of general anesthesia. To avoid these appalling troubles in general anesthesia, we chose spinal anesthesia for a patient with MELAS syndrome receiving appendectomy. The patient obtained adequate anesthesia and good recovery without neurologic sequelae. Although there is little information about the application of regional anesthesia in MELAS patients, we demonstrate that it may be a satisfactory choice. However, it is suggested that regional anesthesia is performed only when neurological abnormalities of spinal cord or peripheral nerves are definitely ruled out.

Differential change in cardiac baroreflex sensitivity estimated by sequence and spectral analysis during etomidate anesthesia

Spontaneous baroreflex sensitivity, high-frequency gain, (0.15-0.35 Hz), and mid-frequency gain (0.07-0.14 Hz) are noninvasive measures of cardiac baroreflex function derived by spontaneous sequence and cross-spectral analysis. To demonstrate the difference between these baroreflex estimates, 14 patients received etomidate (0.3 mg/kg bolus and 0.9 mg/kg/h infusion), lidocaine (60 mg), and vecuronium (0.1 mg/kg) by intravenous injection. The authors found that spontaneous baroreflex sensitivity and high-frequency gain were decreased (p <0.05) after etomidate anesthesia, whereas mid-frequency gain was maintained. Spontaneous baroreflex sensitivity, high-frequency gain, and mid-frequency gain, although compared simultaneously, did not change in a parallel manner. In another 5 patients, who received normal saline only, measures were unchanged. The authors conclude that spontaneous baroreflex sensitivity, high-frequency gain, and mid-frequency gain are not interchangeable. Experimental results on baroreflex control depend on the parameter selected.

First successful ventricular septation of double inlet left ventricle in Taiwan

Patients with a double inlet ventricle may undergo surgery using a modified Fontan procedure, in which the pulmonary ventricle is not utilized, or a procedure in which a pulmonary ventricle is created through ventricular septation. Ventricular septation is preferred to the Fontan procedure because there is better cardiorespiratory response to exercise after surgery. A 4-year-old girl with Holmes heart underwent ventricular septation on 12 May 1998. Pulmonary artery banding had been performed at 3 months of age and rebanding 16 days later. She was well and continued to grow. Ultrafast computed tomography and cardiac catheterization prior to surgery showed a double inlet left ventricle (LV) connected to a right posterior aorta with a right-sided rudimentary right ventricle that drained to the left anterior pulmonary trunk. Left ventricular end diastolic volume was 218% of normal and the ejection fraction was 79%. After debanding and enlargement of the bulboventricular foramen, a 3 x 4-cm composite patch of equine pericardium and Dacron velour was used to septate the ventricle, with transmural stitching at the apical portion. The patient survived the operation with complete atrioventricular block, and was extubated 6 days later. A permanent pacemaker was implanted 1 month later. One year after surgery, she was doing well. Echocardiography revealed paradoxical septal motion with good ventricular function. This is the first report of successful ventricular septation of a double inlet left ventricle performed in Taiwan.

Effect of milrinone on postbypass pulmonary hypertension in children after tetralogy of Fallot repair

BACKGROUND

Postbypass pulmonary hypertension in surgical correction of tetralogy of Fallot (TOF) is a risk for right ventricular failure. Effective management remains a major challenge. Milrinone is a new drug with a unique mechanism of "inodilation", which offers both inotropic and vasodilatory effects. We attempted to determine if application of milrinone could improve cardiopulmonary dysfunction in children after TOF repair.

METHODS

We studied 10 children with postbypass pulmonary hypertension after TOF repair within six months. Heart rate, systolic pulmonary arterial pressure (PAP), systolic arterial blood pressure (SBP), pulmonary capillary wedge pressure and PAP/SBP ratio were recorded. Standard cardiopulmonary bypass (CPB) was performed. After CPB, if PAP/SBP was more than 0.5, pulmonary hypertension was suspected and milrinone was administered with a loading dose of 20 micrograms/kg followed by continuous infusion of 0.2 microgram/kg/minute. Hemodynamics were compared before and after administration of milrinone to evaluate its effect.

RESULTS

significant reduction in PAP/SBP ratio within 15 minutes was found after administration of milrinone. The effect persisted for 24 hours during continuous infusion of milrinone. No remarkable adverse effect was noted in the study.

CONCLUSIONS

We conclude that milrinone is effective in the management of pulmonary hypertension following CPB in children who underwent TOF repair.

Airway management and transesophageal echocardiographic monitoring for pulmonary artery sling

Pulmonary artery sling is an uncommon vascular anomaly and can be life threatening when it causes tracheal compression. We report on a 14-day-old boy who presented with respiratory distress soon after birth. A series of examinations showed tracheal stenosis due to a pulmonary artery sling. Surgery was performed with the aid of cardiopulmonary bypass. The external compression and intrisic stenosis could not be resolved by vascular surgery because of tracheal malacia and a complete tracheal ring. We recommend cutting extra holes 1 to 2 cm from the distal end of the endotracheal tube for endobronchial intubation. The airway obstruction was resolved successfully with a custom-made endobronchial tube. However, the patient died of pneumomediastinum and pneumothorax induced by barotrauma, on the fourth postoperative day.

Antiarrhythmic effect of magnolol and honokiol during acute phase of coronary occlusion in anesthetized rats: influence of L-NAME and aspirin

This study was designed to evaluate the in vivo effect of magnolol and honokiol on the acute phase of coronary ligation in the presence of nitric oxide inhibitor (L-NAME) or cyclooxygenase inhibitor (aspirin). After Sprague-Dawley rats were anesthetized with urethane, the changes of ventricular arrhythmia induced by coronary ligation for 30 min were determined with or without pretreatment with study medications. The incidence and duration of ventricular arrhythmia were significantly reduced after intravenous pretreatment (15 min before coronary ligation) with 10(-7) g/kg magnolol or 10(-7) g/kg honokiol. However, the antiarrhythmic effect of magnolol or honokiol could be abolished with the pretreatment of 1 mg/kg L-NAME, but not with pretreatment of 100 mg/kg aspirin. The abolishment of the myocardial beneficial effect of magnolol and honokiol by L-NAME, instead of aspirin, suggests an involvement of an increased nitric oxide synthesis in the protection offered by magnolol and honokiol against arrhythmia during myocardial ischemia.

Comparison of recovery characteristics of sevoflurane and halothane for outpatient surgery in infants

BACKGROUND

Sevoflurane, a newly approved potent inhaled anesthetic in Taiwan, provides rapid emergence from anesthesia in adults and children. Clinically, it is difficult to accurately assess the rate of recovery from anesthesia in infants. This study was designed to compare the emergence characteristics of halothane with those of sevoflurane having recourse to a respiratory agent monitor in infants undergoing outpatient surgery.

METHODS

Forty infants of ASA class I, scheduled for day-case urologic surgery were studied. Patients were randomly allocated to two groups of 20. Sevoflurane or halothane was used as the inhaled anesthetic. Toward the end of surgery, sevoflurane or halothane was turned off. The concentrations of exhaled sevoflurane or halothane were read every minute after its discontinuation until extubation. The decay curve of the exhaled concentration of either agent was recorded minute by minute for 10 minutes. The time intervals from discontinuation of the inhalation agent to spontaneous movement and tracheal extubation were recorded. Untoward side-effects during emergence were also compared.

RESULTS

Sevoflurane was eliminated faster than halothane. Based on the decay curves of the exhaled concentrations of the two agents, the time constant for halothane was 2.59 minutes and that for sevoflurane was only 1.43 minutes. The time from discontinuation of agent to extubation was also shorter for sevoflurane. Postoperative restlessness or agitation occurred more frequently in infants who received sevoflurane, although the difference was of no statistical significance.

CONCLUSIONS

Sevoflurane is superior to halothane for rapid elimination in infant outpatient surgery as gauged by observation of end-tidal concentration elimination curves recorded with a respiratory agent monitor. No other postoperative side-effect was evident in sevoflurane anesthesia.

Anesthetic management for cesarean section in a pregnant woman with impending acute liver failure--a case report

Acute liver failure includes a constellation of clinical conditions resulting from rapid loss of hepatocyte function. The anesthesiologist may often be asked to anesthetize a patient with acute liver failure before the etiological entity of disease can be completely clarified. Most of the previous reports were concentrated in obstetric or hepatological periodicals. Reports about anesthesia for such patients are scanty. We present a case about a near term pregnant woman with a complication diagnosed as impending acute liver failure, who received total intravenous anesthesia for emergent cesarean section. Pros and cons of different anesthetic techniques for this condition are discussed.

Effects of estrogen on autotomy in normal and ovariectomized rats

Gonadal hormones may modulate analgesia responses induced by acute stress in humans and rats. To evaluate the effects of gonadal hormones in modifying neuropathic pain, we measured autotomy changes following sciatic nerve resection in ovariectomized rats and in the presence of estrogen replacement. Two groups of female rats were subjected to ovariectomy and sham surgery. Each group was then divided into two subgroups receiving subcutaneously sesame oil with or without estradiol benzoate (5 microg/day/rat). All rats then underwent sciatic nerve resection in one hindlimb. Degree of self-mutilation was measured daily for 8 weeks. Estradiol treatment resulted in significantly lower autotomy scores in ovariectomized rats (3.6 +/- 0.6 vs. 5.5 +/- 0.3, p < 0.01) and in sham-operated rats (3.4 +/- 0.7 vs. 5.1 +/- 0.4, p < 0.05). The results of this study indicate that estrogen can modify the autotomy behavior, an indicator of neuropathic pain, in rats after nerve injury.

Effects of dipyridamole, nitroglycerin, and nitroprusside on coronary vascular resistance in rabbits: measurement with pulsed Doppler velocimetry

Dipyridamole, nitroglycerin, and nitroprusside are all effective vasodilators. However, few studies have compared their in vivo coronary vasodilatation effects. The purpose of this study was to compare the effects of these agents on coronary blood flow velocity and vascular resistance in anesthetized, open-chest rabbits. Male New Zealand white rabbits were anesthetized, and a 3-mm, suction-type, pulsed Doppler velocimeter probe was applied to the proximal part of the left anterior descending coronary artery after median sternotomy. The rabbits received infusion of various doses of dipyridamole (0.1 mg/kg, n = 5; 1 mg/kg, n = 5; 10 mg/kg, n = 9), nitroglycerin (0.01 mg/kg, n = 8; 0.1 mg/kg, n = 5; 1 mg/kg, n = 5; 10 mg/kg, n = 7), or nitroprusside (0.01 mg/kg, n = 5; 0.1 mg/kg, n = 5; 1 mg/kg, n = 5). The percent changes in coronary blood flow velocity and coronary vascular resistance were measured. All three vasodilators increased coronary blood flow velocity significantly and decreased coronary vascular resistance dose-dependently. The dose-response curves of dipyridamole, nitroglycerin, and nitroprusside were significantly different from one another (p < 0.01). Dipyridamole at a dose of 10 mg/kg produced the greatest increase in coronary blood flow velocity and the greatest reduction in coronary vascular resistance in anesthetized, open-chest rabbits.

Comparison of subcutaneous hydromorphone with intramuscular meperidine for immediate postoperative analgesia

Intramuscular (i.m.) injection with meperidine is the most common analgesic approach to treat postoperative pain in Taiwan. Hydromorphone (Dilaudid) can provide very potent and rapid analgesic effect through subcutaneous (s.c.) injection. Although hydromorphone is widely used in North America, no study has compared the analgesic efficacy, side effect profiles and patients' satisfaction with the method of injection of hydromorphone s.c. and meperidine i.m. for the immediate post-operative analgesia. In this randomized and double-blind study, 60 female patients scheduled for abdominal total hysterectomy were treated either with 1 mg hydromorphone s.c. (n = 30) or 50 mg meperidine i.m. (n = 30) when they regained consciousness and asked for analgesic treatment in the recovery room. Visual analogue score (VAS) of wound pain was obtained at 0, 10 and 30 min after injection by a blinded observer. The occurrence and severity of nausea, vomiting, dizziness, drowsiness, flatus passage and respiratory depression were recorded. Post-operative analgesia in the ward was maintained by patient-controlled analgesia (PCA) with intravenous morphine. Time to first PCA demand, the number of demands, delivery, delivery/demand ratio and 24 h morphine consumption were documented. We found that VAS was reduced at 10 min and, to a greater extent, at 30 min postinjection in both groups but with no significant difference between the two groups. The occurrence and severity of side effect profiles were similar in both groups except that dizziness was more frequently observed after meperidine injection. Delivery, demand, delivery/demand ratio and 24 hr morphine consumption by PCA were not significantly different between the two groups. Time to first PCA trigger was also similar. Patients receiving hydromorphone s.c. injection exhibited higher satisfactory score than those receiving meperidine i.m. injection. Hydromorphone 1 mg, injected subcutaneously, was as effective as intramuscular meperidine 50 mg while permitting more favorable injection technique and fewer side effects. We suggest that subcutaneous hydromorphone is a good alternative to intramuscular meperidine for postoperative analgesia in the recovery room.

Prevention of hypotension after spinal anesthesia for cesarean section: dextran 40 versus lactated Ringer's solution

BACKGROUND

This study was designed to compare the efficacy of 10% dextran 40 with lactated Ringer's (LR) solution in reducing the incidence and severity of hypotension after spinal anesthesia for Cesarean section.

METHODS

Sixty ASA grade I patients scheduled for Cesarean section were randomized into two groups in a double-blind fashion to receive either 500 ml of dextran 40 or 1000 ml of LR solution prior to induction of spinal anesthesia.

RESULTS

The incidence of hypotension was 16 in 30 (53.3%) in the LR solution group and 8 in 30 (26.7%) in the dextran group (P < 0.05). The required dose of ephedrine for treatment of hypotension was significantly greater in the LR solution group than in the dextran group (15.5 mg versus 3.2 mg, P < 0.05). Neonatal outcome, as determined by Apgar score, was good and similar in both groups.

CONCLUSIONS

We concluded that 500 ml of dextran 40 is more effective than 1000 ml of lactated Ringer's solution in reducing the incidence of hypotension induced by spinal anesthesia.

Preoperative evaluation and postoperative prediction of hemostatic function with thromboelastography in patients undergoing redo cardiac surgery

BACKGROUND

Patients who receive cardiac procedures, in particular "redo" ones, often suffer complications from massive bleeding, largely due to bypass-induced coagulopathies. Cardiopulmonary bypass (CPB) may cause damage of the blood components, both in terms of quality and quantity. In order to investigate the qualitative changes of blood constituents with special regard to coagulation resulting from the complex insult of previous cardiac surgery, thromboelastography (TEG) was used to analyze the whole clotting process.

METHODS

Seventy-four patients who underwent cardiac surgery with CPB were prospectively studied. Of them, 32 patients received "redo" cardiac surgery. Blood samples for routine laboratory coagulation tests (RCT) and TEG examination were drawn before and after cardiopulmonary bypass. Clinically significant bleeding was defined if the chest tube drainage was greater than 100 ml/h for 3 consecutive h or greater than 300 ml in 1 h during the first 8 h after surgery. Prebypass and postbypass coagulation parameters were compared and the percentage of accuracy, false positive and false negative rate were deduced from calculation.

RESULTS

In the TEG tracings, preoperative alpha angle and maximum amplitude were significantly decreased in the "redo" group when compared with primary group, indicating less competent platelet function and platelet-fibrin interaction. Lower platelet count was also found by conventional coagulation tests in "redo" patients. Postoperatively, higher percentage of excessive hemorrhage was also noted in the "redo" group (42.8% vs. 27.5% in primary group). However, a much lower predictive accuracy was found in "redo" patients in comparison with primary cardiac patients (53.5% vs. 90%).

CONCLUSIONS

We concluded that thromboelastography failed to predict postoperative hemorrhage in "redo" cardiac patients and the graphic recordings derived could not be treated as a guide of transfusion therapy. We thought that inferior preoperative hemostatic status and severer coagulopathy might be responsible for the differences between "redo" and primary cardiac patients.

The neuromuscular effects of mivacurium in adults with priming technique during nitrous oxide-fentanyl anesthesia: a randomized comparative study with succinylcholine

BACKGROUND

We investigated the neuromuscular effects of equipotent dose (3 x ED90) of mivacurium either given as a single bolus or under the influence of priming technique, comparing with that of succinylcholine in adults undergoing elective surgery during nitrous oxide-narcotic anesthesia.

METHODS

Sixty ASA class I patients of either sex with age between 16 to 49 years were randomly assigned to 3 groups for a trial of mivacurium under nitrous oxide-narcotic anesthesia. Group I (non-priming group, n = 20) received mivacurium 0.25 mg/kg straight as a single intubating dose; Group II (priming group, n = 20) received an intubating dose of 0.225 mg/kg mivacurium which was preceded by 0.025 mg/kg 3 min earlier; and Group III received an intubating bolus of succinylcholine 1 mg/kg. Thenar electromyogram response to supramaximal train-of-four stimulation of the ulnar nerve at 12-s intervals was used to determine neuromuscular blockade. Blood pressure and heart rate were recorded before and at 1-min interval for 3 min after injection of drugs. Data were presented as mean +/- standard deviation. P value < 0.05 was considered statistically significant.

RESULTS

The onset time of mivacurium was accelerated by priming procedure in comparison with the nonpriming technique (2.0 min vs. 2.7 min), but it was much slower than that of succinylcholine (0.8 min). The priming procedure did not influence the duration of action or recovery. Side effects of mivacurium, such as cutaneous flushing and hypotension, were minimal at this dose in our patients.

CONCLUSIONS

Priming technique (with 10% of the total dose as the priming dose, and 3 min as the priming interval) can hasten the onset of mivacurium in adults during nitrous oxide-narcotic anesthesia without influencing the duration of action and recovery time.

Right ventricular dysfunction after tetralogy repair in a pediatric patient with successful ECMO support--a case report

Right ventricular dysfunction after surgical repair of tetralogy is a serious life threatening complication. Although pulmonary vasodilators and inotropes can be used for cardiac support in tetralogy repair, these drugs may be ineffective in some patients. To date extracorporeal membrane oxygenation (ECMO) support may be used effectively in these patients when medical therapy fails. We report a case with successful ECMO support in right ventricular dysfunction and pulmonary hypertension after total surgical correction of Fallot's tetralogy. ECMO circuit was instituted in the operating room due to difficulty in weaning from cardiopulmonary bypass in spite of aggressive medical therapy. We reviewed and discussed the indications, contraindications of application of ECMO and patient survival with treatment of ECMO. At the same time we wish to share our limited experience we gained in our first attempt of ECMO support.

Effect of BL-10 (tianzhu), BL-11 (dazhu) and GB-34 (yanglinquan) acuplaster for prevention of vomiting after strabismus surgery in children

BACKGROUND

Stimulation of P6 (Neiguan) acupoint can prevent nausea and vomiting in adults. However, there is no antiemetic effect in children undergoing strabismus surgery. The effect of P6 may act only on hollow organs; in contrast, BL-10 (Tianzhu), BL-11 (Dazhu) and GB-34 (Yanglinquan) are more related to the meridians of the eye. Therefore these three more relevant acupoints, BL-10, BL-11 and GB-34 were stimulated to evaluate the antiemetic effect in children undergoing strabismus surgery.

METHODS

Sixty-five children, ASA physical status I, between 3 and 14 years of age, were randomly divided into two groups as follows: placebo group (n = 31) and acuplaster group (n = 34). Bilateral acupressure using the Vital Point Needleless Acuplaster (Koa, Japan) was applied to BL-10, BL-11 and GB-34 points the night before surgery. Anesthesia was induced and maintained with halothane and nitrous oxide in oxygen. Postoperative emesis was assessed at early (at PACU) and late (at ward) phases, and was recorded by an investigator blind to the treatment characteristics.

RESULTS

In the early emesis phase, the incidence of vomiting was 35.5% for placebo group, compared with 14.7% for acuplaster group. In the late emesis phase, acuplaster patients had a significantly lower incidence of vomiting (23.5% vs. 58.1% in placebo patients, p < 0.05). The overall postoperative vomiting incidence in the acuplaster patients in a 24 h period which was significantly decreased was 29.4% as opposed 64.5% in the placebo group (p < 0.05).

CONCLUSIONS

The results demonstrated that prophylactic use of bilateral noninvasive acuplaster on the BL-10, BL-11, and GB-34 acupoints significantly reduces vomiting after strabismus correction. The mechanism may be dispersal of these three acupoints, thus diminishing the parasympathetic stimulation resulting from surgical traction of eye muscles.

Effect of trilinolein on superoxide dismutase activity and left ventricular pressure in isolated rat hearts subjected to hypoxia and normoxic perfusion

Oxygen-derived free radicals have been implicated in the development of myocardial injury during hypoxia/reperfusion. Antioxidants can effectively inhibit the formation of free radicals and ameliorate the myocardial damage which may occur during hypoxia/reperfusion. Trilinolein is a triacylglycerol recently purified from the traditional Chinese medicinal plant Panax pseudo-ginseng. It has linoleic-acid residues as the only type of fatty acid residue in all three esterified positions of the triacyglycerol. It has been proposed that decreased endogenous superoxide dismutase (SOD) activity may contribute to free radical-mediated reperfusion injury of the ischemic myocardium. In the present study, when isolated rat hearts were subjected to hypoxia for 10, 30, 60 and 90 min without normoxic perfusion, a significant decrease in Mn-SOD activity was shown throughout the period of hypoxia, whereas the Cu.Zn-SOD activity was increased at 10 and 30 min but was not different from the baseline at 60 and 90 min of hypoxia. In rat hearts pretreated with 10(-7) mol/l trilinolein and subjected to 60 min of hypoxia without normoxic perfusion, Cu.Zn-SOD was augmented compared with baseline and compared with hearts subjected to 60 min of hypoxia without trilinolein, whereas Mn-SOD activity was still reduced compared with baseline, although less so than after 60 min of hypoxia without trilinolein. Pretreatment with trilinolein was associated with better preservation of left ventricular function during hypoxia and more rapid return to recovery during normoxic perfusion. This myocardial protective effect may be related to an antioxidant effect through potentiation of SOD, particularly Cu.Zn-SOD during hypoxia.