Sang Wook Shin

Percutaneous Vertebroplasty and Facet Joint Block

It is surprising that about 24% of patients with benign osteoporotic vertebral fracture die within a year from respiratory infection and urinary tract infection because of coughing and voiding difficulties, depending on the sites of compression fractures. We reviewed 500 patients on whom percutaneous vertebroplasty (PVP) was performed, at 612 levels in terms of patient selection, operation technique, medication, and clinical outcomes during the follow-up course for 2 yr study period. To confirm the most painful level among the multiple fracture sites, physical examination after facet joint block under the fluoroscope was the most reliable method. The mean total lumbar spine fracture threshold of bone mineral density was 0.81±0.05 g/cm2. The mean changes of numeric rating scale scores, Oswestry Disability Index except sex life, and Karnofsky performance status were -72.00, -83.50 and +60.62% in the osteoporosis group and -51.89, -45.02, and 69.03% in the tumor group. Complications related to the procedure were lateral spinal cord damage, transient paresthesia and transient hypotension. PVP with facet joint block is a profitable method for the vertebral compression fracture because of low risk and short duration of procedure with a high chance to result in pain relief and early mobilization.

Optimal dose of dexmedetomidine for sedation during spinal anesthesia

Background Sedation in spinal anesthesia can reduce patients anxiety and discomfort. Dexmedetomidine has a sedative, hypnotic, analgesic, and minimal respiratory depression effect. However, use of the dexmedetomidine is associated with prolonged recovery. This study was designed to investigate the optimal dose of intravenous dexmedetomidine for proper sedation with minimal recovery time in spinal anesthesia. Methods One hundred twenty eight patients, aged 20-70 years (58.8 ± 0.7), were recruited. After performing the spinal anesthesia with hyperbaric bupivacaine (13 mg), a loading dose of dexmedetomidine (1 µg/kg) was administered for 10 min, followed by the maintenance infusion of the following: Group A (n = 33; normal saline), Group B (n = 35; dexmedetomidine 0.2 µg/kg/hr), and Group C (n = 39; dexmedetomidine 0.4 µg/kg/hr). Heart rate, blood pressure, and the bispectral index score (BIS) were recorded during the operation. In the recovery room, modified aldrete score (MAS) was measured. Results There were no significant differences in mean blood pressure and heart rate among the three groups. BIS was not significantly different among the three groups from baseline to 60 min after the infusion of dexmedetomidine. BIS were significantly increased in Group A after 70 and 80 min, and Group A and B after 90, 100, 110 min of dexmedetomidine infusion (P < 0.05). MAS was higher in Group A as compared to Group B and C, within 30 min after admission in the recovery room (P < 0.05). Conclusions The loading dose (1 µg/kg/10 min) of dexmedetomidine was sufficient for surgery of less than 60 min. Dexmedetomidine infusion followed by maintenance dose (0.2 µg/kg/hr) was sufficient for surgery within 90 min.

The median effective effect-site concentration of remifentanil for minimizing the cardiovascular changes to endotracheal intubation during desflurane anesthesia in pediatric patients

Background Desflurane has the most rapid onset and offset of action among the volatile anesthetic agents used for general anesthesia, but it can cause airway reactivity, tachycardia, and hypertension during induction, especially in pediatric patients. This study was designed to determine a median effective effect-site concentration (EC50) of remifentanil to prevent the cardiovascular changes due to tracheal intubation during the 1 minimum alveolar concentration (MAC) desflurane inhalation, which was required to prevent movement in response to a noxious stimulus in 50% of subjects, in pediatric patients. Methods Twenty-four pediatric patients between the ages 5-15 years were enrolled in this study. We injected thiopental intravenously, at the same time remifentanil was infused by Target Controlled Infusion (TCI) device. When the target effect-site concentration (Ce) of remifentanil reached a preset level, desflurane was administrated through the facial mask. Then, we assessed the signs of desflurane related airway reactivity and cardiovascular changes for 2 min. The up-and-down criteria was a 20% change in systolic blood pressure (SBP) and a heart rate (HR) between just prior to intubation and 1 min after intubation. The EC50 of remifentanil was calculated from 8 independent pairs using Dixons up-and-down method. Results We studied 24 pediatric patients in range of 1-5 ng/ml of the Ce of remifentanil. No patient showed airway reactivity during the study. The EC50 of remifentanil to suppress the hemodynamic changes after tracheal intubation during desflurane anesthesia was calculated as 3.4 ± 0.9 ng/ml. Conclusions In pediatric anesthesia, the EC50 of remifentanil to minimize the cardiovascular changes due to tracheal intubation during 1 MAC desflurane anesthesia was 3.4 ± 0.9 ng/ml.

Infusion Methods for Continuous Interscalene Brachial Plexus Block for Postoperative Pain Control after Arthroscopic Rotator Cuff Repair

Background Infusion methods during regional analgesia using perineural catheters may influence the quality of postoperative analgesia. This study was conducted to compare the effects of combined or bolus-only infusion of 0.2% ropivacaine on the postoperative analgesia in interscalene brachial plexus block (ISBPB) with perineural catheterization. Methods Patients scheduled for arthroscopic rotator cuff repair were divided into two groups, one that would receive a combined infusion (group C, n = 32), and one that would receive intermittent infusion (group I, n = 32). A perineural catheter was inserted into the interscalene brachial plexus (ISBP) using ultrasound (US) and nerve stimulation, and 10 ml of 0.2% ropivacaine was administered. After the operation, group C received a continuous infusion of 4 ml/h, and a 4 ml bolus with a lockout interval of 60 min. Group I received only a 4 ml bolus, and the lockout interval was 30 min. Postoperative pain by the numeric rating scale (NRS) and the forearm muscle tone by the manual muscle test (MMT) were checked and evaluated at the following timepoints: preoperative, and postoperative 1, 4, 12, 24, 36, and 48 h. Supplemental opioid requirements, total consumed dose of local anesthetic, and adverse effects were compared between the two groups. Results Sixty-four patients completed the study and the postoperative values such as operation time, time to discharge, and operation site were comparable. There were no differences in NRS scores and supplemental opioid requirements between the two groups. The MMT scores of group I at 4 and 12 h after surgery were significantly higher than those of group C (P < 0.05). The total consumed dose of local anesthetic was significantly lower in group I than in group C (P < 0.05). The adverse effects were not different between the groups. Conclusions The bolus-only administration of 0.2% ropivacaine provided a similar analgesic effect with a lower total volume of local anesthetic and decreased motor weakness compared to combined infusion. Therefore, bolus-only administration is an effective postoperative analgesic method in ISBPB with perineural catheterization after rotator cuff repair.

The proper effect site concentration of remifentanil for prevention of myoclonus after etomidate injection

Background Etomidate frequently induces myoclonus when administered intravenously with bolus injection during anesthetic induction. This can be bothersome for the anesthesiologist. The dose of remifentanil appropriate for preventing myoclonus without side effects was investigated. Methods All patients with American Society of Anesthesiologists (ASA) physical status I-III were divided into three groups (n = 33 per group) according to the pretreatment effect site concentration of remifentanil (Ultiva, Glaxo-Wellcome, München, Germany) of 0, 2 or 4 ng/ml (Group N: 0 ng/ml, Group R: 2 ng/ml, Group Q: 4 ng/ml) by a target controlled infusion (TCI) system. After a 0.3 mg/kg dose of etomidate was injected intravenously for over 1 minute for anesthetic induction, myoclonus was observed. Before the etomidate injection, the patients were pretreated with remifentanil and their side effects were monitored. Results The number of patients showing myoclonus was significantly different among the groups. The incidence of myoclonus was 81%, 12% and 0% (groups N, R, and Q, respectively, P < 0.01). Side effects including bradycardia and hypotension did not occur in either Group R or Q. Chest wall rigidity occured in 45% of patients in Group Q. Conclusions Administration with a 2 ng/ml effect site concentration of remifentanil could reduce the incidence of myoclonus caused by etomidate bolus injection without chest wall rigidity.

Dexmedetomidine does not produce vasocontraction on human isolated gastroepiploic artery

Background Recently, the addition of dexmedetomidine to sedation regimens after cardiac surgery had been reported and there is a possibility that dexmedetomidine can cause vasoconstriction. Vasopressin has been used as a prophylactic treatment for refractory vasodilatory shock during coronary artery bypass graft (CABG). Also, vasopressin may play an important role in initiating spasms at the graft artery. Here we evaluate the direct effect of dexmedetomidine on isolated human gastroepiploic arteries and the synergistic effect of dexmedetomidine and vasopressin. Methods Discarded gastroepiploic arteries from elective subtotal gastrectomy (n = 10) were used in this study. We measured the level of contraction in isolated human gastroepiploic arteries induced by increasing concentrations of dexmedetomidine (10-10 to 10-6 M) with or without vasopressin (10-10, 10-9 M). Arterial contractions caused by increasing concentrations of vasopressin (10-10 to 10-7.5 M) with or without dexmedetomidine (10-9, 10-7 M) were also measured in the tissue samples. Results Supraclinical concentrations of dexmedetomidine elicited contractions at concentrations of 10-7 M and 10-6 M (P < 0.05 versus resting tension). The same concentrations of dexmedetomidine (10-7, 10-6 M) significantly enhanced vasopressin-induced contractions (P < 0.05 versus vasopressin-induced contraction). Vasopressin produced concentration-dependent contractions and vasopressin (10-10, 10-9.5, 10-9 M) also increased the intensity of dexmedetomidine (10-7 M) induced contractions. Conclusions There was a synergistic effect between supraclinical doses of dexmedetomidine and vasopressin on the degree of contraction in isolated human gastroepiploic arteries. However, a sedative dose of dexmedetomidine (clinical dose: 0.2-0.7 µg/kg/hr, plasma concentration: 0.36-1.25 ng/ml) did not enhance vasopressin induced-contraction in isolated human gastroepiploic arteries.

Left ventricular outflow tract obstruction due to a left ventricular myxoma that was misidentified as an accessory mitral valve tissue

We report obstruction of the left ventricle outflow tract (LVOT) caused by cardiac myxoma that was misidentified as an accessory mitral valve tissue preoperatively. A 65-year-old woman presented with chest discomfort that persisted for 7 days. Transthoracic echocardiography (TTE) revealed a mobile, low-echogenic, balloon-shaped mass attached to the anterior mitral valve leaflet and papillary muscle, which was suspected to be an accessory mitral valve tissue. Because the mass caused LVOT obstruction and it could result in hemodynamic instability, emergency operation was performed. Intraoperative transesophageal echocardiography (TEE) was performed, and the mass had irregular margins and was pedunculated, with a stalk originating from the left ventricle (LV) wall and extending to the lateral chordae of the mitral valve. The surgeon excised the mass filled with the myxomatous mass, which was yellowish and gelatinous and had a stiff stalk, and histopathologic diagnosis confirmed a myxoma. Although mitral valve or LV myxomas are rare, TEE is a useful tool for distinguishing a myxoma from other intracardiac masses, such as vegetation or an accessory mitral valve tissue.

Medications for osteoporotic pain

Received March 9, 2017. Accepted March 10, 2017. Correspondence to: Sang Wook Shin Department of Anesthesia and Pain Medicine, Pusan National University School of Medicine, Beomeo-ri, Mulgeum-eup, Yangsan 50612, Korea Tel: +82-55-360-2129, Fax: +82-55-360-2129, E-mail: shinsw@pusan.ac.kr This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright c The Korean Pain Society, 2017 Patients with osteoporosis may suffer from pain, and chronic persistent pain stimuli irritates the nervous system to develop to a vicious cycle of chronic pain [1]. If there are compression fractures of vertebrae which are weakened by osteoporosis, back pain from that injury would affect the quality of life, and sometimes it may persist for a long period and not be well controlled. Therefore, prevention and treatment of osteoporosis in such patients is a challenge, and diagnosing and treating osteoporosis in advance is one task in the prevention and treatment of pain in such patients. For the treatment of osteoporosis, medications like calcitonin, parathyroid hormone, estrogen administration, etc. have been used, and bisphosphonates are also commonly used. Bisphosphonates bind to the minerals of the bone and inhibit osteoclastic action, so they are known to inhibit bone resorption. Until recently, they were the most effective pharmacological agents for the prevention and treatment of osteoporosis. But they have remained medications that are difficult to take, even though many improved types have been developed. Patient compliance is still a big problem with any those who have difficulty due to side effects such as gastrointestinal discomfort [2]. Among the drugs approved by the U.S. Food and Drug Administration for osteoporosis, denosumab, a receptor activator of the nuclear factor kappa B ligand (RANKL) inhibitor has been introduced [3]. It works in receptor-based action during bone remodeling. This drug could overcome the compliance problems with patients, as it is administered biannually. In this issue, medications for the treatment of osteoporosis, with related mechanisms, are reviewed with an emphasis on the introduction of the newly approved drug denosumab [4]. It could become another essential weapon in the treatment of pain from osteoporosis along with bisphosphonates [5].

Medications in Treatment of Postherpetic Neuralgia

Among many various neuropathic pain syndromes, postherpetic neuralgia (PHN) is one of the most typical and difficult neuropathic pains to control in some patients. To prevent progression to PHN, vaccination against herpes zoster has been developed. There are reviews about herpes zoster vaccination in recently published articles in the Korean Journal of Pain (KJP) and other journals [1,2]. As is written in those and other reviews, once herpes zoster progresses to PHN, the syndrome could result in severe personal and social burdens for patients. Although PHN has been known for a long time and is a typical neuropathic pain, many treatment modalities and options continue to be reported. There have even been case reports on the effectiveness of systemic vitamin C administration and transforaminal epidural magnesium injection [3-6]. The treatment for PHN varies among hospitals, and commonly used pharmacological and interventional methods include anticonvulsants and interlaminar epidural blocks [7]. According to the suggested treatment algorithm for acute or subacute herpes zoster and PHN, adjuvant pharmacological medications are tricyclic antidepressants, anticonvulsants, opioids, tramadol, topical lidocaine, and capsaicin [8]. In this months issue of KJP, Joo et al. [9] report on the controllability of PHN with nefopam. They used systemic nefopam during the titration of the oral medication. Although there have been many clinical reports on nefopam for the treatment of pain, to date, few reports may be found regarding the treatment of chronic neuropathic pain. Nefopam has been known to be effective in acute postoperative pain and postanesthetic shivering [10-13]. In animal research, intrathecal nefopam is reported to have an antinociceptive effect in an acute inflammatory rat pain model [14]. Systemic administration of nefopam was shown to enhance the analgesia with morphine and nimesulide and decrease pain behavior and reduce adverse effects in a chronic constrictive nerve injury rat model [15]. Nefopams mechanism of action is suggested to be through the activities of the serotonin, glutamate, and dopamine circuits [16], and it might be successfully tried in the treatment of various chronic neuropathic pain conditions. If we consider the chronicity and intractability of many neuropathic pain conditions, and the continuity of medication in these patients, many trials for neuropathic treatments are anticipated.

Postoperative Orthostatic Intolerance and Gender Differences

Received September 13, 2013. Accepted September 13, 2013. Correspondence to: Sang Wook Shin, MD Department of Anesthesia and Pain Medicine, Pusan National University School of Medicine, Beomeo-ri, Mulgeum-eup, Yangsan 626-770, Korea Tel: +82-55-360-2752, Fax: +82-55-360-2149, E-mail: shinsw@pusan.ac.kr This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright c The Korean Pain Society, 2013 LETTER TO EDITORS