Nanoscale imaging of rat atrial myocytes by scanning ion conductance microscopy reveals heterogeneity of T-tubule openings and ultrastructure of the cell membrane

In contrast to ventricular myocytes, the structural and functional importance of atrial transverse tubules (T-tubules) is not fully understood. Therefore, we investigated the ultrastructure of T-tubules of living rat atrial myocytes in comparison with ventricular myocytes. Nanoscale cell surface imaging by scanning ion conductance microscopy (SICM) was accompanied by confocal imaging of intracellular T-tubule network, and the effect of removal of T-tubules on atrial excitation-contraction coupling (EC-coupling) was observed. By SICM imaging, we classified atrial cell surface into 4 subtypes. About 38% of atrial myocytes had smooth cell surface with no clear T-tubule openings and intracellular T-tubules (smooth-type). In 33% of cells, we found a novel membrane nanostructure running in the direction of cell length and named it 'longitudinal fissures' (LFs-type). Interestingly, T-tubule openings were often found inside the LFs. About 17% of atrial cells resembled ventricular myocytes, but they had smaller T-tubule openings and a lower Z-groove ratio than the ventricle (ventricular-type). The remaining 12% of cells showed a mixed structure of each subtype (mixed-type). The LFs-, ventricular-, and mixed-type had an appreciable amount of reticular form of intracellular T-tubules. Formamide-induced detubulation effectively removed atrial T-tubules, which was confirmed by both confocal images and decreased cell capacitance. However, the LFs remained intact after detubulation. Detubulation reduced action potential duration and L-type Ca2+ channel (LTCC) density, and prolonged relaxation time of the myocytes. Taken together, we observed heterogeneity of rat atrial T-tubules and membranous ultrastructure, and the alteration of atrial EC-coupling by disruption of T-tubules.

Nanoscale imaging of rat atrial myocytes by scanning ion conductance microscopy reveals heterogeneity of T-tubule openings and ultrastructure of the cell membrane

In contrast to ventricular myocytes, the structural and functional importance of atrial transverse tubules (T-tubules) is not fully understood. Therefore, we investigated the ultrastructure of T-tubules of living rat atrial myocytes in comparison with ventricular myocytes. Nanoscale cell surface imaging by scanning ion conductance microscopy (SICM) was accompanied by confocal imaging of intracellular T-tubule network, and the effect of removal of T-tubules on atrial excitation-contraction coupling (EC-coupling) was observed. By SICM imaging, we classified atrial cell surface into 4 subtypes. About 38% of atrial myocytes had smooth cell surface with no clear T-tubule openings and intracellular T-tubules (smooth-type). In 33% of cells, we found a novel membrane nanostructure running in the direction of cell length and named it 'longitudinal fissures' (LFs-type). Interestingly, T-tubule openings were often found inside the LFs. About 17% of atrial cells resembled ventricular myocytes, but they had smaller T-tubule openings and a lower Z-groove ratio than the ventricle (ventricular-type). The remaining 12% of cells showed a mixed structure of each subtype (mixed-type). The LFs-, ventricular-, and mixed-type had an appreciable amount of reticular form of intracellular T-tubules. Formamide-induced detubulation effectively removed atrial T-tubules, which was confirmed by both confocal images and decreased cell capacitance. However, the LFs remained intact after detubulation. Detubulation reduced action potential duration and L-type Ca2+ channel (LTCC) density, and prolonged relaxation time of the myocytes. Taken together, we observed heterogeneity of rat atrial T-tubules and membranous ultrastructure, and the alteration of atrial EC-coupling by disruption of T-tubules.

Stanford type A aortic dissection in a patient with Marfan syndrome during pregnancy: a case report / 대한마취과학회지

Aortic dissection during pregnancy is a devastating event for both the pregnant woman and the baby. We report a case of acute aortic dissection (Stanford type A) in a pregnant woman with Marfan syndrome at the 29th week of gestation. She underwent a cesarean section followed by an ascending aorta and total arch replacement with cardiopulmonary bypass, without a prior sternotomy. The hemodynamic parameters were kept stable during the cesarean section by using inotropes and vasopressors under transesophageal echocardiography monitoring. The newborn survived after endotracheal intubation and management in a neonatal intensive care unit.

The anesthetic experience of implantable left ventricular assist device insertion: a case report / 대한마취과학회지

Because of insufficient number of donor hearts for cardiac transplantation, the use of implantable left ventricular assist device (LVAD) has been increasing as an alternative. During this procedure, the fundamental role of anesthesiologists would be to maintain stable hemodynamics. This report describes the anesthetic case of a 75-year-old man who underwent implantable LVAD placement as a destination therapy of his heart failure in Korea. The procedure and anesthesia were uneventful with transesophageal echocariographic guide. He moved to the ward on postoperative day 10 without fatal complication.

Air embolism during off-pump coronary artery bypass graft surgery: A case report / 대한마취과학회지

There have been several reports of gas embolism occurring during off-pump coronary artery bypass graft (OPCAB) surgery. However, all these cases of air embolism were associated with the repair of venous circulation, using a CO2 blower. In this report, we describe a rare case of air embolism in the coronary arteries associated with the use of a CO2 blower during OPCAB. There was no injury to the veins during OPCAB. The air embolism was treated successfully with cardiopulmonary bypass.

Postoperative nausea and vomiting after endoscopic thyroidectomy: total intravenous vs. balanced anesthesia / 대한마취과학회지

BACKGROUND: Endoscopic thyroidectomy was recently introduced and has been rapidly accepted by surgeons and patients. The present study was conducted to estimate and compare the incidences of postoperative nausea and vomiting (PONV) after endoscopic thyroidectomy using two different anesthetic methods: sevoflurane based balanced anesthesia; total intravenous anesthesia (TIVA). METHODS: Ninety nine female patients that were scheduled to undergo elective endoscopic thyroidectomy under general anesthesia were enrolled. These patients were randomly allocated to receive sevoflurane based balanced anesthesia (BA group) or propofol-remifentanil anesthesia (TIVA group). PONV was evaluated using a 4-point Likert scale, and pain using a visual analogue scale (VAS; range 0 to 100) for 0-2, 2-6, and 6-24 hours postoperatively. At 24 hours postoperatively, overall patient satisfaction regarding PONV and pain were recorded. RESULTS: The incidence of PONV was 14.6% in the TIVA group and 51.3% in the BA group. The incidence of nausea at 0-2 and 2-6 hours postoperatively was lower in the TIVA group than in the BA group (4.2% vs. 35.9%, 6.3% vs. 23.1%, respectively), but no between-group difference was observed at 6-24 hours postoperatively (8.3% vs. 5.1%). Antiemetic usage at 0-2 and 2-6 hours was lower in the TIVA than the BA group (4.2% vs. 38.5%, 6.3% vs. 23.1%), but no between-group difference was observed for 6-24 hours (6.3% vs. 7.7%). There were no differences in pain or in patient satisfaction. CONCLUSIONS: After endoscopic thyroidectomy, total intravenous anesthesia with propofol-remifentanil is associated with less PONV during the early postoperative period (0-6 hours) than sevoflurane based balanced anesthesia.

Dilution and slow injection reduces the incidence of rocuronium-induced withdrawal movements in children / 대한마취과학회지

BACKGROUND: The aim of this study was to evaluate whether slow injection of diluted rocuronium could reduce rocuronium-induced withdrawal movements effectively in children. METHODS: After loss of consciousness, rocuronium 0.6 mg/kg was administered into 171 children according to the pre-assigned groups as follows: Group CF, injection of non-diluted rocuronium over 5 seconds; Group CS, injection of non-diluted rocuronium over 1 minute; Group DF, injection of diluted rocuronium (10 times) over 5 seconds; Group DS, injection of diluted rocuronium over 1 minute. An investigator who was blind to the injection techniques recorded patient movements followed by rocuronium injection. RESULTS: The incidence of withdrawal movement in Group CF was highest among the groups (all P < 0.0001). Moreover, withdrawal movement was less frequently observed in Group DS than in Groups CS and DF (P = 0.021 and P = 0.007, respectively). CONCLUSIONS: Slow injection of diluted rocuronium reduced the incidence of withdrawal movements in children.

Suppression of CFTR-mediated Cl- Secretion of Airway Epithelium in Vitamin C-deficient Mice

Hyperoxic ventilation induces detrimental effects on the respiratory system, and ambient oxygen may be harmful unless compensated by physiological anti-oxidants, such as vitamin C. Here we investigate the changes in electrolyte transport of airway epithelium in mice exposed to normobaric hyperoxia and in gulonolacton oxidase knock-out (gulo[-/-]) mice without vitamin C (Vit-C) supplementation. Short-circuit current (Isc) of tracheal epithelium was measured using Ussing chamber technique. After confirming amiloride-sensitive Na+ absorption (DeltaIsc,amil), cAMP-dependent Cl- secretion (DeltaIsc,forsk) was induced by forskolin. To evaluate Ca2+-dependent Cl- secretion, ATP was applied to the luminal side (DeltaIsc,ATP). In mice exposed to 98% PO2 for 36 hr, DeltaIsc,forsk decreased, DeltaIsc,amil and DeltaIsc,ATP was not affected. In gulo(-/-) mice, both DeltaIsc,forsk and DeltaIsc,ATP decreased from three weeks after Vit-C deprivation, while both were unchanged with Vit-C supplementation. At the fourth week, tissue resistance and all electrolyte transport activities were decreased. An immunofluorescence study showed that the expression of cystic fibrosis conductance regulator (CFTR) was decreased in gulo(-/-) mice, whereas the expression of KCNQ1 K+ channel was preserved. Taken together, the CFTR-mediated Cl- secretion of airway epithelium is susceptible to oxidative stress, which suggests that supplementation of the antioxidant might be beneficial for the maintenance of airway surface liquid.

Comparison of the effectiveness of lidocaine and salbutamol on coughing provoked by intravenous remifentanil during anesthesia induction / 대한마취과학회지

BACKGROUND: Coughing is a side effect of opioids that is rarely studied. Here, we evaluated the incidence of remifentanil induced coughing during anesthesia induction in an attempt to identify its risk factors and to examine the preventive effects of lidocaine and salbutamol. METHODS: A total of 237 patients scheduled to undergo general anesthesia were allocated randomly into three groups. Group C received no medication, while Group L received 2% lidocaine at 0.5 mg/kg intravenously 1 minute prior to remifentanil infusion and Group S inhaled one metered aerosol puff of salbutamol 15 minutes prior to entering the operating room. Remifentanil was infused at 5 ng/ml by target controlled infusion and coughing was measured for five minutes and graded as none, mild, moderate, or severe based on the number of coughs. RESULTS: The incidences of coughing were 30.4%, 25.3%, and 35.4% in Groups C, L, and S, respectively. The incidences, onset times, and severity of coughing did not differ significantly among groups. In addition, multivariate analysis showed that non-smoking and a lower body weight were risk factors of remifentanil-induced coughing (odds ratio, 8.13; P = 0.024, 1.11, and 0.004, respectively). CONCLUSIONS: The incidence of remifentanil-induced coughing was 30%. A total of 0.5 mg/kg lidocaine and 1 metered aerosol puff of salbutamol did not prevent coughing. Non-smoking and low body weight were found to be risk factors of remifentanil-induced coughing.

Is Intravenous Patient Controlled Analgesia Enough for Pain Control in Patients Who Underwent Thoracoscopy?

This prospective randomized study was conducted to evaluate the efficacy of two common analgesic techniques, thoracic epidural patient-controlled analgesia (Epidural PCA), and intravenous patient-controlled analgesia (IV PCA), in patients undergoing lobectomy by the video-assisted thoracic surgical (VATS) approach. Fifty-two patients scheduled for VATS lobectomy were randomly allocated into two groups: an Epidural PCA group receiving an epidural infusion of ropivacaine 0.2%+fentanyl 5 microg/mL combination at a rate of 4 mL/hr, and an IV PCA group receiving an intravenous infusion of ketorolac 0.2 mg/kg+fentanyl 15 microg/mL combination at a rate of 1 mL/hr. Pain scores were then recorded using the visual analogue scale at rest and during motion (VAS-R and VAS-M, 0-10) for five days following surgery. In addition, we measured the daily morphine consumption, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), satisfaction score, and the incidence of side effects. Thirty-seven patients out of 52 completed the study (18 in the Epidural PCA group, 19 in the IV PCA group). There were no differences in the pain scores, analgesic requirements, pulmonary function, satisfaction score, and the incidence of side effects between groups. This indicates that IV PCA and Epidural PCA are equally effective to control the postoperative pain after VATS lobectomy, which suggests that IV PCA may be used instead of Epidural PCA.

Protective Effects of Gabapentin on Allodynia and alpha2delta1-Subunit of Voltage-dependent Calcium Channel in Spinal Nerve-Ligated Rats

This study was designed to determine whether early gabapentin treatment has a protective analgesic effect on neuropathic pain and compared its effect to the late treatment in a rat neuropathic model, and as the potential mechanism of protective action, the alpha2delta1-subunit of the voltage-dependent calcium channel (alpha2delta1-subunit) was evaluated in both sides of the L5 dorsal root ganglia (DRG). Neuropathic pain was induced in male Sprague-Dawley rats by a surgical ligation of left L5 nerve. For the early treatment group, rats were injected with gabapentin (100 mg/kg) intraperitoneally 15 min prior to surgery and then every 24 hr during postoperative day (POD) 1-4. For the late treatment group, the same dose of gabapentin was injected every 24 hr during POD 8-12. For the control group, L5 nerve was ligated but no gabapentin was administered. In the early treatment group, the development of allodynia was delayed up to POD 10, whereas allodynia was developed on POD 2 in the control and the late treatment group (p<0.05). The alpha2delta1-subunit was up-regulated in all groups, however, there was no difference in the level of the alpha2delta1-subunit among the three groups. These results suggest that early treatment with gabapentin offers some protection against neuropathic pain but it is unlikely that this action is mediated through modulation of the alpha2delta1-subunit in DRG.

The Effective Steroid Dose of Caudal Epidural Injection with Unilateral Epidural Catheter Position in Patients with Symptomatic Herniated Nucleus Purposus / 대한마취과학회지

BACKGROUND: The epidural steroid injection is commonly used in the management of chronic low back pain and radiating pain. We compared the efficacy of 40, 60, and 80 mg of methylprednisolone acetate in patients with lumbar herniated disc disease treated with caudal epidural block. METHODS: Seventy-two patients with lumbar herniated nucleus purposes on magnetic resonance imaging were included.All patients received fluoroscopically guided caudal epidural injections, with the guidewire-reinforced epidural catheter introduced through a Tuohy needle.After confirming the catheter tip position at the affected nerve root, contrasts were injected until patients felt discomfort in their site of pain.24 patients in each group received 40 mg, 60 mg, 80 mg of methylprednisolone acetate, respectively.We evaluated the improvements by pain relief scale (0-100%) after 2 weeks. RESULTS: There are no significant differences in the pain improvement between three groups (P = 0.537 ). CONCLUSIONS: Sixty and 80 mg methylprednisolone acetate injection during caudal epidural block showed no further benefit compared to 40 mg injection.

Spinal myoclonus on upper extremities following spinal anesthesia: A case report / 대한마취과학회지

Clonic movement is a rare complication that occurs after neuraxial blockade. We report our experience with an 18-year-old man developing myoclonic movement on his both upper extremities following intrathecal injection of 0.5% hyperbaric bupivacaine for varicocelectomy. One and half hour after spinal anesthesia, he developed bilateral, rhythmic myoclonic movements on upper extremities. Two days after surgery, neck flexion was observed. Symptoms sustained for about one month but frequency and severity of clonic movement had been reduced by anticonvulsants and muscle relaxant therapy. Four weeks later, he recovered without any complication.

Risk Factors of Pressure Sore in Patients undergoing General Anesthesia / 대한마취과학회지

BACKGROUND: The occurrences of pressure sores have an extensive impact on patients and the medical team. Pressure sores decrease quality of life and productivity, as well as increase the overall cost of treatment. The purpose of this study was to identify the risk factors associated with pressure ulcers among surgical patients. METHODS: Data were collected from 588 patients who underwent general anesthesia. The data included age, gender, weight, height, body mass index, ASA status, surgical position, anesthesia time, pre-and postoperative hemoglobin concentration, serum albumin, NYHA class, co-morbidity, steroid use, body temperature, use of warming water mattress and preoperative hospital admission day. The patient's skin was inspected closely before surgery and again within 24 hours after surgery and the locations and severity of skin breakdowns were assessed. RESULTS: Twenty-five patients (4.3%) developed pressure sores during surgery. The hemoglobin concentration change between the preoperative and postoperative period (> or =2 g/dl), position during surgery, length of stay before operation (> or =4 days), anesthesia time (> or =5 hours) and decrease in body temperature (> or =0.5degrees C) were significantly related to the development of pressure sores (P < 0.05). CONCLUSIONS: Five risk factors for pressure ulcers were confirmed. The anesthesiologist can decrease hemoglobin and modify body temperature; therefore, attention should be given to these risk factors during the operation.

The Effect of Simultaneous Electroacupuncture on Ankle Sprain Pain in Rats / 대한마취과학회지

BACKGROUND: Simultaneous acupuncture to two or more acupoints has been used to improve acupuncture-induced effects in clinical practice. However, there is little evidence supporting the effects of simultaneous electroacupuncture (EA). This study examined whether simultaneous EA with 2 and 2 Hz or 2 and 100 Hz can produce synergic effects on ankle-sprained pain in rats. METHODS: Ankle sprain pain was induced by manually overextending the lateral ligament of the right ankle in rats. Electrical stimulation with 2 Hz was delivered to the Yangno acupoint (SI6) and with 2 or 100 Hz to the Zusanli (ST36), either individually or simultaneously. The level of pain evoked by the ankle sprain was measured by the stepping force of the sprained paw during walking. The analgesic effects of simultaneous EA was evaluated by the percentage recovery of the stepping force at 1, 2 and 4hr after EA and compared to that of individual EA. RESULTS: Individual EA significantly increased the stepping force of the ankle-sprained paw during walking, but there is no difference in the effect between electrical stimulation with 2 and 100 Hz EA. Simultaneous EA with 2 and 2 Hz or 2 and 100 Hz showed no significant improvement of the stepping force compared to individual EA. CONCLUSIONS: Individual EA with 2 and 100 Hz produced comparable analgesic effects. Simultaneous EA applied to the SI6 and ST36 acupoints produced no synergic interaction, therefore has no beneficial effect for ankle-sprained pain compared to individual EA.

The Effects of the Preoperative Education about Analgesics and Patient-Controlled Analgesia (PCA) on the Consumption of Analgesics after Operation / 대한마취과학회지

BACKGROUND: The purpose of this study is to evaluate the patients' general perception about the analgesics and the effects of the preoperative education about analgesics and patient-controlled analgesia (PCA). METHODS: One hundred patients scheduled for elective gastrectomy were randomly allocated into two groups. In control group (n = 50), patients were given conventional preanesthetic visit with questionnaire survey on PCA one day before operation. In study group (n = 50), patients were sufficiently explained about postoperative analgesia and PCA by anesthesiologist and given precise explanation sheet about PCA. Total amounts of drug used in PCA as well as rescue analgesics, the pain scores, and side effects were compared. RESULTS: 62.2% of patients had much information from various sources that analgesics effects positively in the recovery phase, but actually 73.7% of patients considered that analgesics do not seem to have any influence on the recovery after operation. There was no difference between the amounts of total PCA used, rescue analgesics, and the pain scores. However, the educated patients complained less dizziness at postoperative days (POD) one. Also, the number of patients excluded from study due to the PCA discontinuation secondary to related side effects was less in educated patients (P = 0.025). CONCLUSIONS: Preoperative education about analgesics and PCA failed to demonstrate significant decrease in the amount of analgesics and of pain scores. However, it lowered the incidence of PCA discontinuation due to side effects.

A Correlation between Low Back Pain and Associated Factors: A Study Involving 772 Patients who Had Undergone General Physical Examination

Many factors are associated with the development of low back pain. Among them, exercise, obesity, smoking, age, educational level and stress are the most common. This study examined the association of these factors with low back pain. An additional aim was to determine a procedure for preventing low back pain. This study analyzed the responses to a questionnaire sent to 772 individuals who had undergone a medical examination at this hospital in 2003 and excluded the individuals who had shown symptoms or their test results indicated a particular disease. Assuming that there were no variables, individuals who exercised regularly 3-4 times per week would have a lower chance of having low back pain than those who did not exercise regularly. The analysis revealed that individuals with a college degree or higher education have a lower chance of experiencing low back pain than those with only a high school education or even college drop-outs. When the other variables were constant, age, extent of obesity (body mass index), smoking and level of stress were not found to affect the development of low back pain. The level of education was associated with the development of low back pain. However, regular exercise 3-4 times per week or more would be most effective in reducing the incidence and duration of low back pain.

Effects of Insulin on the Resuscitation by Epinephrine for Bupivacaine-Induced Cardiovascular Depression in Dogs / 대한마취과학회지

BACKGROUND: Because of the difficulty of resuscitation caused by bupivacaine-induced cardiotoxicity, the choice of resuscitation medication is still unclear. We investigated whether insulin can improve outcomes of resuscitation by epinephrine from bupivacaine-induced cardiovascular collapse. METHODS: Twenty-four mongrel dogs were randomly allocated to one of the two groups: an EPI group (n = 12), and an EPI + RI group (n = 12). Sixty minutes after induction of general anesthesia, baseline measurement of hemodynamic parameters and arterial blood gas tension was performed. Bupivacaine infusion was started at a rate of 0.5 mg/kg/min and kept until mean arterial blood pressure fell below 40 mmHg and heart rate 40 beats per minute. At this point, bupivacaine infusion was stopped and resuscitation was started, with epinephrine in EPI group and epinephrine combined with regular insulin in EPI + RI group. RESULTS: Bupivacaine infusion caused significant decreases in mean arterial blood pressure, heart rate, cardiac output, and systemic vascular resistance and increases in mean pulmonary blood pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance, and central venous pressure. The recovery rate of EPI + RI group (8/12) was higher than that of EPI group (2/12). CONCLUSIONS: Combined administration of epinephrine and regular insulin improves outcomes of resuscitation of bupivacaine-induced cardiovascular collapse. Therefore, we believe that prompt administration of insulin should be strongly considered in case of bupivacaine-induced cardiotoxicity.

The Determination of Optimal Intramuscular Injection Time of Midazolam as a Premedication Agent for Minimizing Decrease of Serum Potassium / 대한마취과학회지

BACKGROUND: Pre-operative anxiety is known to cause an increase in plasma catecholamine levels, which, in turn, attributes to the decrease in serum K+ concentration. Midazolam is one of the most commonly used premedication agent for the purpose of anxiolysis in the pre-operative period. In this study, by measuring serum K+ concentration, we investigated the optimal intramuscular injection time for midazolam which maximally prevents the reduction of serum K+ concentration. METHODS: One hundred twenty three patients undergoing breast surgery were randomly assigned to one of 5 groups. Control group (n = 24) had no premedication. 30-minute group (n = 30), 60-minute group (n = 25), 90-minute group (n = 22) and 120-minute group (n = 22) received IM injection of midazolam (0.05 mg/kg) at 30, 60, 90, and 120 minutes before induction of anesthesia, respectively. Anxiety level, serum K+ concentrations, blood pressures and heart rates of all patients were measured at 7:00pm of the day before surgery and immediately before induction of anesthesia. RESULTS: Serum K+ concentrations of all groups showed significant decrease in the preinduction time compared with those values at 7:00 pm of the day before surgery. There were no significant changes of heart rates in all groups. Blood pressures immediately before induction of anesthesia elevated compared with those at 7"00 pm of the day before surgery in all groups. Immediately before induction of anesthesia, the K+ levels of 60-minute and 90-minute groups were higher than those of the control group. At this time, the rates of hypokalemia (K+ <3.5 mEq/L) of 60-minute and 90-minute groups were lower than those of the control group. 30-minute and 60-minute groups had significantly lower anxiety levels than the control group. CONCLUSIONS: When we consider anxiety and serum potassium levels, the optimal intramusculr injecting time of midazolam was 60 minutes before induction of anesthesia.

Effects of Epidural Naloxone on Pruritus Induced by Hydromorphone Epidural Patient-Controlled Analgesia / 대한통증학회지

BACKGROUND: Opioid delivered by epidural patient-controlled analgesia (PCA) is effective in relieving pain after surgery, but it is associated with side effects, such as nausea, vomiting, pruritus, respiratory depression, and urinary retention. The purpose of this study was to compare hydromorphone related side effects and the quality of analgesia when naloxone was added to epidural PCA regimen. METHODS: Fifty-two thoracotomy patients with PCA were allocated blindly into two groups. Patients in group H (n = 26) received continuous epidural hydromorphone (16microgram/ml) in 0.1% bupivacaine; patients in group N (n = 26) received an epidural infusion containing naloxone (2 microgram/ml) and hydromorphone (16microgram/ml) in 0.1% bupivacaine. The basal rate of PCA was 4 ml/hr and the demand dose was 1.5 ml with a lockout time of 15 min. Pain intensity, sedation, pruritus, nausea and vomiting, respiratory depression were checked at 6, 12, 24 hours postoperatively. RESULTS: The Visual Analog Scale (VAS) scores were significantly lower in group H than in group N. There were no significant differences in the overall incidence of pruritus, nausea and sedation between the two groups. CONCLUSIONS: Continuous epidural infusion of naloxone combined with hydromorpho-ne is not effective in reducing the incidence and severity of pruritus induced by epidural hydromorphone.