Pyoderma Gangrenosum of the Preauricular Area with Ulcerative Colitis: A Case Report and Review

Pyoderma gangrenosum (PG) is primarily, a sterile, inflammatory, neutrophilic dermatosis, characterized by recurrent cutaneous ulceration with mucopurulent or hemorrhagic exudate. The incidence of PG is uncertain, but it is estimated to be about 3-10 patients per million per year. It occurs most commonly on the lower legs, but has been reported at other sites of the body as well. The causes of PG are unknown, but about 50-70% of cases are associated with other diseases, mainly inflammatory bowel disease. We hereby report a case of PG in a 21-year-old male, with a history of ulcerative colitis (UC). After appropriate diagnostic methods including biopsy for pathologic confirmation, sigmoidoscopy and computed tomography, we excluded other diseases and the lesion was diagnosed as PG. We then carried out regular dressing of the wound, while UC was treated with steroid and immunosuppressant medication, with inputs from the department of gastroenterology during the hospital stay. There occurred recurrence of the skin lesion, 7 months after discharge, after which they improved. UC has been in the remission state as per the follow-up, since 2 years.

Point-of-care ultrasound may reduce emergency department length of stay in children with nonspecific manifestations of intussusception

PURPOSE: To investigate whether performance of point-of-care ultrasound (POCUS) can reduce emergency department length of stay (EDLOS) for children with nonspecific manifestations of intussusception (NMI), defined as 2 or less manifestations of the classic triad of intussusception, and/or vomiting. METHODS: We reviewed medical records of 141 consecutive children with intussusception aged 6 years or younger who visited the emergency department of Asan Medical Center in Seoul, Korea from May 2014 through April 2016 and underwent diagnostic radiology ultrasound and pneumatic reduction. The children were grouped according to whether they underwent POCUS or not (POCUS and no POCUS groups, respectively). POCUS was performed to children with NMI by an attending emergency physician who had completed a POCUS training course endorsed by the Korean Society of Pediatric Emergency Medicine. We measured EDLOS, which consisted of door-to-reduction and observation times. These time intervals were compared between the 2 groups. RESULTS: Of 112 eligible children, 65 (58%) underwent POCUS. The median EDLOS was shorter in the POCUS group than in the no POCUS group (566 minutes, interquartile range [IQR] 497 to 765 vs. 745 minutes, IQR 551 to 981; P = 0.003). The median door-to-reduction and observation times were also shorter in the POCUS group (105 vs. 138 minutes, P < 0.001 and 440 vs. 628 minutes, P = 0.008, respectively). These differences were possibly due to the performance of POCUS and the trend toward early discharge after pneumatic reduction. We found 1 child with false negative result on POCUS, but there may have been more. CONCLUSION: Performance of POCUS may reduce EDLOS in children with NMI.

Delayed peripartum cardiomyopathy after emergency cesarean section / 대한마취과학회지

No abstract available.

Perimortem cesarean section in a pregnant woman with flecainide-induced ventricular tachycardia: A case report

Flecainide is a drug used to manage supraventricular and ventricular arrhythmias. It is also effective in the treatment of fetal tachyarrhythmia through administration to the mother. However, flecainide toxicity may cause serious complications, including cardiac conduction disturbance, ventricular arrhythmia, resulting in syncope and sudden death. We describe here a 27-year-old woman at 31 weeks of gestation who experienced ventricular tachycardia, leading a perimortem cesarean section. On her past medication history, she has taken overdose of oral flecainide for the treatment of fetal atrial flutter. Just after neonatal delivery, her ventricular tachycardia was successfully reverted to a sinus rhythm through administration of intravenous lidocaine and hemodynamics were stabilized. According to her clinical signs and symptoms, we presume the ventricular tachycardia was likely induced by flecainide toxicity, although serum flecainide concentration could not be measured in our institution.

Adipokine Concentrations in Pregnant Korean Women with Normal Glucose Tolerance and Gestational Diabetes Mellitus / 당뇨병

BACKGROUND: The aims of this study were to compare adipokine concentrations of pregnant women in the 24th~28th weeks of gestation to those of non-pregnant women. We compared the concentrations of adipokines in women with gestational diabetes mellitus (GDM), gestational impaired glucose tolerance (GIGT) and normal glucose tolerance (NGT). We also investigated the role of adipokines in the development of gestational glucose intolerance. METHODS: We surveyed 129 pregnant women who underwent a 100 g oral glucose tolerance test (OGTT) during the 24th~28th weeks of gestation. Participants were classified into three groups: (1) NGT (n = 40), (2) GIGT (n = 45), and (3) GDM (n = 44). Pregnant subjects with NGT were matched to non-pregnant controls for BMI and age (n = 41). RESULTS: Pregnant women with NGT exhibited significantly decreased adiponectin levels and elevated leptin levels compared to non-pregnant controls. Mean plasma resistin levels were significantly higher in women with GDM and GIGT than in women with NGT. Resistin and fasting glucose were significant predictors for the development of gestational glucose intolerance. CONCLUSION: Plasma adiponectin levels were decreased and leptin levels were increased in pregnant subjects with NGT compared to BMI and age matched non-pregnant controls. Women with GDM and GIGT exhibit significantly elevated concentrations of resistin compared with women with NGT. Increased resistin levels were also associated with the development of gestational glucose intolerance. Resistin may play an important role on the development of gestational glucose intolerance in Korean women.

The Effects of Superior Cervical Sympathetic Ganglion Block on the Acute Phase Injury and Long Term Protection against Focal Cerebral Ischemia/Reperfusion Injury in Rats / 대한통증학회지

BACKGROUND: Cerebral blood vessels are innervated by sympathetic nerves from the superior cervical ganglia (SCG), and these nerves may influence the cerebral blood flow. The purpose of the present study was to evaluate the neuroprotective effect of superior cervical sympathetic ganglion block in rats that were subjected to focal cerebral ischemia/reperfusion injury. METHODS: Eighty male Sprague-Dawley rats (270-320 g) were randomly assigned to one of two groups (the ropivacaine group and a control group). In all the animals, brain injury was induced by middle cerebral artery (MCA) reperfusion that followed MCA occlusion for 2 hours. The animals of the ropivacaine group received 30microl of 0.75% ropivacaine, and their SCG. Neurologic score was assessed at 1, 3, 7 and 14 days after brain injury. Brain tissue samples were then collected. The infarct ratio was measured by 2.3.5-triphenyltetrazolium chloride staining. The terminal deoxynucleotidyl transferase mediated dUTP-biotin nick-end labeled (TUNEL) reactive cells and the cells showing caspase-3 activity were counted as markers of apoptosis at the caudoputamen and frontoparietal cortex. RESULTS: The death rate, the neurologic score and the infarction ratio were significantly less in the ropivacaine group 24 hr after ischemia/reperfusion injury. The number of TUNEL positive cells in the ropivacaine group was significantly lower than those values of the control group in the frontoparietal cortex at 3 days after injury, but the caspase-3 activity was higher in the ropivacaine group than that in the control group at 1 day after injury. CONCLUSIONS: The study data indicated that a superior cervical sympathetic ganglion block may reduce the neuronal injury caused by focal cerebral ischemia/reperfusion, but it may not prevent the delayed damage.

Effects of magnesium infusion on hemodynamic and autonomic changes in healthy volunteers / 대한마취과학회지

BACKGROUND: Magnesium has been used for treatments and preventions of various situations, such as cardiovascular disease and pre-eclampsia. And it also used for decreasing demands of anesthetics and analgesics during anesthesia. Activity of autonomic nervous system has important roles for homeostasis of cardiovascular system, and its dysfunction affects mortality and morbidity. Because there are few reports about effects of magnesium infusion on autonomic nervous system, we investigated effects of magnesium infusion on hemodynamic and autonomic changes using variable autonomic function tests in healthy volunteers. METHODS: Hemodynamic parameters, heart rate variability, blood pressure variability, and baroreflex sensitivity were evaluated before and after magnesium infusion of 30 mg/kg during 20 min in twenty healthy volunteers. Cold face test, valsalva maneuver were also performed before and after magnesium infusion. RESULTS: Low-frequency components of blood pressure variability decreased after magnesium infusion (P = 0.026). There were no significant differences in blood pressure, heart rate, cardiac output, stroke volume, total peripheral resistance, heart rate variablility and baroreflex sensitivity between before and after magnesium infusion. Increases of diastolic blood pressure during cold face test decreased significantly after magnesium infusion (P = 0.022). In addition, no significant hemodynamic and autonomic changes were found during valsalva maneuver. CONCLUSIONS: Central sympathetic vasomotor tone decreased after magnesium infusion of 30 mg/kg during 20 min in healthy volunteers. However, it had no effects on parasympathetic system and baroreflex sensitivity.

Acute Hemothorax after Percutaneous Nephrolithotomy : A case report / 대한마취과학회지

Percutaneous nephrolithotomy (PCNL) is a common procedure done for stone removal, as it is less invasive than an open procedure. But, several complications may occur. Hemothorax is a rare but severe chest complication of the supracostal puncture during PCNL. We experienced an acute hemothorax and lung collapse just after PCNL in a 66-year-old male patient with left renal stone. A chest tube was inserted for drainage and was removed after 9 days, when a chest X-ray revealed good expansion of lung.

Fatal Cardiac and Pulmonary Embolisms during Radical Nephrectomy and Inferior Vena Cava Thrombectomy: A case report / 대한마취과학회지

Intraoperative pulmonary embolism can result in severe hemodynamic instability, including cardiac arrest. Therefore, immediate diagnosis and proper treatment are required. We report a case of the acute cardiac and pulmonary embolisms during radical nephrectomy and inferior vena cava (IVC) thrombectomy in a patient with renal cell carcinoma with thrombus in the IVC. We diagnosed the cardiac embolism intraoperatively using the transesophageal echocardiogram, and performed emergent cardiac and pulmonary embolectomies immediately. After the surgery, the patient was discharged without any complication.

Left Atrial Thrombus Diagnosed by Transesophageal Echocardiography Immediately after Induction in a Patient with Middle Cerebral Artery Infarction: A case report / 대한마취과학회지

Stroke is one of the most common causes of death; in particular, cardiac source of embolism may be responsible for 15-20% of ischemic strokes. Here we report a case of left atrial thrombus diagnosed by transesophageal echocardiography (TEE) immediately after induction of general anesthesia in a patient with infarction of the middle cerebral artery. In this case, an emergent craniectomy was cancelled and medical treatment was performed. This case report shows that TEE taken in the operating room may play an important role in the change of treatment plan in a patient displaying acute mental change.

The Influence of Sevoflurane Anesthesia on Various Kinds of Spontaneous Baroreflex Sensitivities / 대한마취과학회지

BACKGROUND: In contrast to classic drug injection method, various types of noninvasive spontaneous baroreflex sensitivity (SBRS) methods have been developed using the computer analysis of the spontaneous fluctuation of heart rate and arterial blood pressure for baroreflex evaluation. In this study, we evaluated the effects of sevoflurane anesthesia on SBRS by comparing various SBRS estimates and their correlations before and after sevoflurane anesthesia. METHODS: Radial arterial pressure and electrocardiography were recorded in 50 patients before and after sevoflurane anesthesia. We derived six SBRS indices from the methods including sequence, alpha-index, transfer function analysis and impulse response function. The sequence method measured an average of baroreflex sequences. The alpha-index used the average of the square roots of the ratios between the RRI and SBP spectral power. The transfer function index used RRI and SBP cross-spectral magnitude for this index. The impulse response function method employed an inverse Fourier transform. RESULTS: All SBRS and accompanying correlations were reduced after sevoflurane anesthesia. Low (44%) and high (4%) frequency transfer function gain and sequence SBRS (4%) failed to be computed out of some patients after sevoflurane anesthesia due to poor coherence and absence of a valid sequence. CONCLUSIONS: Sevoflurane anesthesia caused marked depression of SBRS and weakened their correlations. Therefore, it is necessary to understand the characteristics of each SBRS method for selecting an appropriate method during anesthesia.

Inguinal Hernia following Lumbar Spinal Surgery in the Prone Position: A case report / 대한마취과학회지

An inguinal hernia shows that the protruding viscus exits from the endoabdominal fascial sac through the internal inguinal ring. Because an inguinal hernia is usually associated with incarceration, obstruction and even strangulation, it must be quickly treated whenever observed. Although there are several predisposing factors of the development of inguinal hernia, relatively little is a case report of the inguinal hernia developed by the increased intra-abdominal pressure during general anesthesia. In this case, we report a patient who developed the unexpected recurrence of left inguinal hernia following lumbar spinal surgery in prone position by increasing intra-abdominal pressure. After manual reduction was performed promptly by general surgeon, the patient was discharged without any complication on the eighth postoperative day.

Influence of Anesthesia Induction with Ketamine on Baroreflex Control of Heart Rate / 대한마취과학회지

BACKGROUND: It is reported that ketamine increases central sympathetic activity as well as catecholamine reuptake inhibition. However, little has been known about baroreflex control of heart rate in ketamine anesthetized humans. Thus, the aim of this study was to analyze the effect of ketamine on spontaneous baroreflex sensitivity (BRS) during ketamine induction of anesthesia. METHODS: Beat-by-beat arterial blood pressure and electrocardiogram at 5 min before and 10 min after ketamine administration (2 mg/kg) were recorded in twenty healthy living liver transplant donors. Spontaneous BRS was assessed by sequence method and transfer function analysis method. RESULTS: Spontaneous BRS assessed by sequence method, BRSsequence, decreased from 13.7 +/- 6.3 to 7.8 +/- 4.5 ms/mmHg (P < 0.001). Spontaneous BRS assessed by low frequency transfer function method decreased from 10.9 +/- 5.4 to 7.0 +/- 4.1 ms/mmHg and by high frequency transfer function method from 14.8 +/- 9.2 to 8.7 +/- 8.8 ms/mmHg, respectively (P < 0.05). CONCLUSIONS: The spontaneous BRS was decreased during ketamine induction of general anesthesia. These results suggest that anesthesia induction with ketamine impairs baroreflex control of heart rate, which may provoke hemodynamic instability.

The Effect of Rilmenidine Pretreatment on the Cardiovascular Toxicity Caused by Intravenous Bupivacaine by Autonomic Nervous System Analysis in Anesthetized Cats / 대한마취과학회지

BACKGROUND: This study was designed to assess the effects of rilmenidine on the autonomic nervous system, and to evaluate whether it prevents bupivacaine-induced cardiovascular toxicity during intravenous bupivacaine infusion in anesthetized cats. METHODS: Thirty male cats were randomly divided into a control group (n = 15) and a rilmenidine group (n = 15). Following the injection of rilmenidine (10microgram/kg), systolic blood pressures (SBP) and R-R intervals (RRI) were recorded for 5 minutes. Then power spectral analyses of the SBP and RRI, and transfer function analysis were conducted to evaluate the autonomic nervous system. During the infusion of bupivacaine (0.5 mg/kg/min), blood pressures, heart rates, times to reach each events, and bupivacaine doses were measured at the first QRS modification, the first dysrhythmia, at 25% (HR25) and 50% reductions in baseline heart rate, and at 25% and 50% reductions in baseline mean arterial pressure and at final systole. RESULTS: The high frequency (HF) power of heart rate variability (HRV) was significantly elevated in the rilmenidine group versus the control group. Magnitude HF was significantly higher in the rilmenidine group than in the control group. The onset of dysrhythmia correlated significantly with the HFs of HRV and baroreflex sensitivity (BRS). Except for HR25, the rilmenidine group showed significantly higher bupivacaine doses and delayed event onsets versus the control group. CONCLUSIONS: We suggest that pretreatment with rilmenidine delays the onset of dysrhythmia by increasing vagal tone and BRS and by reducing cardiovascular toxicity when bupivacaine is infused continuously to isoflurane anesthetized cats.

Complete Atrioventricular Nodal Block in Patient Undergoing Left Vagus Nerve Stimulation: A case report / 대한마취과학회지

There are virtually no cognitive and systemic side-effects associated with vagus nerve stimulation (VNS), which makes it a valuable treatment modality for patients with a poor tolerance to antiepileptic drugs. The safety of VNS therapy have been established in clinical studies, but there are few reports on the cardiac side effect associated with the intraoperative lead testing for implantation of the device for VNS. We report a patient with refractory epilepsy who experienced a complete atrioventricular block intraoperatively as a result of inadvertently high current intensity during the initial testing for implantation of a left vagus nerve stimulator.

Intubating Laryngeal Mask Airway for Difficult Airway / 대한마취과학회지

BACKGROUND: Almost all anesthesiologists are encounter a difficult airway occasionally, which is probably the most important cause of anesthesia related morbidity and mortality. The intubating laryngeal mask airway (ILMA; FastarachTM; laryngeal mask company, Henley-on-Thames, UK) is a new device for tracheal intubation. It is an ideal rescue airway since it can be placed quickly and used as a conduit for endotracheal intubation, while ventilation is ongoing. This prospective study was underttaken from January, 1997 to December, 2004 to evaluate the appropriateness of the ILMA for anticipated or unanticipated difficult airways. METHODS: After institutional committee approval, seventy eight patients were enrolled in this study. The anticipated group compromised thirty five patients and the unanticipated group forty three. In the unanticipated group, anesthesia was induced with thiopental sodium and vecuronium and maintained with enflurane or isoflurane, whereas in the anticipated group, awake intubation with nerve block was done before intubation. The success of the technique (within five attempts), the number of attempts, the durations of the successful attempts, and adverse events (desaturation, bleeding) were recorded. RESULTS: The rate of successful tracheal intubation with ILMA was 92.7%. The numbers of attempts and the times to success were not significantly different between the two groups. Adverse events occurred significantly more frequently in the unanticipated group. Conclusion: The ILMA is a useful device for the management of patients with a difficult airway and may be a valuable alternative to direct laryngoscopy or fiberoptic intubation when neck movement is unfavorable or in those with an unanticipated difficult airway.

The Changes in Serum and Cerebrospinal Fluid Ca2+, Mg2+, and Ca2+/Mg2+ Ratio in Neuropathic Rats / 대한마취과학회지

BACKGROUND: Central sensitization of neuropathic pain is associated with an influx of extracellular calcium via the opening of N-methyl-D-aspartate (NMDA) receptor-gated ion channels, which is usually blocked by a magnesium plug. Many studies have found that intrathecal or intraperitoneal magnesium suppress neuropathic pain. Therefore, it is possible that serum and cerebrospinal fluid Ca2+, Mg2+, and Ca2+/Mg2+ ratio are changed in neuropathic pain. The purpose of this study was evaluated changes in serum and cerebrospinal fluid Ca2+, Mg2+, and Ca2+/Mg2+ ratio in neuropathic rats. METHODS: Male Sprague-Dawley rats were prepared with tight ligation of the left lumbar 5th and 6th spinal nerves to produce neuropathic pain. The threshold of mechanical allodynia was evaluated by the up-down method using withdrawal response to a von Frey filaments stimulus on the 3rd, 7th, and 14th day. Rats with a threshold of less than 4 gram were selected as the experimental group. On the 16th day, serum and cerebrospinal fluid Ca2+, Mg2+, and Ca2+/Mg2+ ratio were measured. Experimental group data were then compared with those of an unoperated control group and an unligated sham group; each group contained 10 animals. RESULTS: No statistic differences were found between groups. CONCLUSIONS: Our results suggest that serum and cerebrospinal fluid Ca2+, Mg2+, and Ca2+/Mg2+ ratio in neuropathic rats do not differ from those of normal rats because of physiologic homeostasis is maintained by active transport through the blood-brain-barrier despite of activation of NMDA receptor-gated ion channels. However, we believe that the Mg2+ ion-dependent voltage-gating in rats with neuropathic pain may be deficient in a chronic condition due to a decreased Mg2+ binding affinity of the NMDA receptor-gated channel, as has been found in hippocampal granule cells in epileptic rats.

Effects of Phenytoin on Rocuronium-induced Neuromuscular Blockade Using a Rat Phrenic Nerve-diaphragm Preparation / 대한마취과학회지

BACKGROUND: Chronic anticonvulsant therapy with phenytoin antagonizes the action of nondepolarizing muscle relaxants. Rocuronium is a new non depolarizing muscle relaxant of rapid onset and intermediate duration. This study was designed to investigate the effects of phenytoin on rocuronium-induced neuromuscular blockade using a rat phrenic nerve-diaphragm preparation. METHODS: Male Sprague-Dawley rats (200 g, n = 70) were randomly allocated into a control group (C, n = 10), three phenytoin-pretreated groups (PP, n = 30) and three phenytoin-non-pretreated groups (PNP, n = 30). In phenytoin-pretreated groups, phenytoin 50 mg/kg/day was administered intraperitoneally once a day for one day (PP1D), seven days (PP7D) or twenty eight days (PP28D). Animals were anesthetized with 40 mg/kg of thiopental sodium intraperitoneally and the diaphragm with the phrenic nerve were dissected, and the phrenic nerve-diaphragm preparation was suspended in 100 ml of Krebs solution in an organ bath. The bath was aerated with 95% O2-5% CO2 at 32oC, and the phrenic nerve was stimulated with supramaximal intensity using a stimulator. Twitch responses were measured using a precalibrated force displacement transducer and recorded. The cumulative dose-response relationships of rocuronium and phenytoin were determined. After one hour's stabilization, rocuronium 100 microgram was added to the bath, and when a stable 3-5 twitch was obtained, incremental 50 microgram doses of rocuronium were added to obtain more than 95% neuromuscular twitch inhibition at 0.1 Hz. In the phenytoin-non-pretreated group, phenytoin was administered simultaneously with the initial dose of rocuronium to a phenytoin concentration of 1 microgram/ml (PNP1), 10 microgram/ml (PNP10), or 100 microgram/ml (PNP100) in Krebs solution. Data were analyzed by probit and logistic models. In the PP group, the plasma concentration of phenytoin was analyzed by high performance liquid chromatography. RESULTS: The dose-response curve of rocuronium was significantly shifted to the left in the PNP100 group (P < 0.05), and significantly shifted to the right in the PP28D group (P < 0.05). The plasma phenytoin concentration was found to be directly proportional to the duration of the phenytoin pretreatment. CONCLUSIONS: The potency of rocuronium is reduced in chronic phenytoin therapy and increased after an acute high dose of phenytoin.

Effect of LiCl on Iodine Kinetics in Thyroid Cancer Cell Lines Transduced by Recombinant Adenovirus Containing Sodium Iodide Symporter(NIS) Gene / 대한내분비학회지

BACKGROUND: Lithium is known to increase the retention of iodide in the thyroid gland, or in well differentiated thyroid cancer tissue. The effects of lithium on the function of the sodium iodide symporter (NIS) protein, especially when the lithium is increased in the retention of iodide in NIS-producing cells, the effect of lithium, on the kinetics of undifferentiated thyroid cancer cells transduced by a recombinant adenovirus containing the NIS gene, were checked. METHOD: Human NIS cDNA was inserted into pAxCAwt, a recombinant adenoviral cosmid vector, where the E1 & E2 genes have been deleted, making Rad-hNIS, which was propagated in 293 cells. The iodide uptake was evaluated by the 125I uptake assay in the undifferentiated thyroid cancer cells, ARO, FRO and NPA, following the infection with Rad-hNIS (1 or 10 MOI) in the presence, or absence, of LiCl at optimized concentrations. The iodide efflux was evaluated by the 125I efflux assay, for 1 hour, in the same cells expressing the NIS in the presence, or absence, of LiCl. Similar experiments were performed in the normal thyroid cell line, FRTL-5, cultured in 6H5 media. RESULTS: LiCl, at concentrations over 1.0mM, caused a significant decrease in the cell viability, as evaluated by trypan blue dye exclusion, in a dose dependent manner. When infected with Rad-hNIS, the iodide uptake was not affected by the LiCl in the ARO or NPA cells. However, LiCl(0.1and 1.0mM) increased the iodide uptake by 50 to 100%(vs. control) in the Rad-hNIS transduced FRO cells. In the Rad-hNIS transduced FRO cells, the iodide was released rapidly from the cells, with only 20.7+/-4.8% of the iodide uptake remaining at 1 hour, which was no different in the presence of LiCl (24.5+/-7.9%). The iodide efflux was not affected by the LiCl in the FRTL-5 cells cultured in the presence of TSH. CONCLUSION: These results suggest that the lithium-induced iodide retention in the thyroid gland, or in well differentiated thyroid cancer tissue, is not caused by the effect of the lithium on the NIS function, or the function of proteins or channels, involved in iodide transport via cell membranes. Although the iodide uptake can be markedly increased by the expression of NIS, with the transduction of Rad-hNIS, in undifferentiated thyroid cancer cells, the iodide taken up is rapidly released from the cells. A method for inducing the iodide retention in the cell should be elucidated in order to render the NIS gene therapy effective.

Effect of Rilmenidine and Clonidine Premedication on the Cardiovascular Action of Phenylephrine and Nitroprusside in Rats / 대한마취과학회지

BACKGROUND: Patients premedicated with clonidine often present with hypotension and bradycardia. The hypotensive patient premedicated with clonidine should be given a vasopressor to treat hypotension. In these patients, an augmented vasopressor response would be shown. Rilmenidine as an allied drug of clonidine is an antihypertensive agent with selectivity for the imidazoline receptor that acts centrally by reducing sympathetic overactivity. This study was designed to evaluate the effect of clonidine and rilmenidine on changes in mean blood pressure and baroreflex sensitivity following phenylephrine and nitroprusside administration. METHODS: Sixty Sprague-Dawley rats were assigned randomly into one of three groups, control group (n = 20), clonidine group (n = 20) or rilmenidine group (n = 20). Saline (control group), clonidine 30ng/kg (clonidine group) or rilmenidine 300ng/kg (rilmenidine group) were intraperitoneally injected respectively. Following the injection, a phenylephrine and nitroprusside test were performed. RESULTS: The percent change in mean blood perssure from the baseline values in the control group, clonidine group and rilmenidine group were 35 +/- 18%, 54 +/- 17% and 62 +/- 38%, respectively. There was no difference between the baroreflex sensitivity in the pressure (phenylephrine) test (0.94 +/- 0.43, vs 1.05 +/- 0.62, vs 1.13 +/- 0.59 msec/mmHg). In contrast, the slopes of the depressor (nitroprusside) test were decreased in rats receiving clonidine and rilmenidine (0.51 +/- 0.34, vs 0.12 +/- 0.08, vs 0.18 +/- 0.09 msec/mmHg, P < 0.05). CONCLUSIONS: It is concluded that the rilmenidine and clonidine groups showed a more augmented pressure response to vasopressors than the control group. Therefore, the decreased dosage of vasopressors is recommended to treat hypotension in rilmenidine premedicated patients.