Won Uk Koh

The effects of prophylactic bolus phenylephrine on hypotension during low-dose spinal anesthesia for cesarean section

BACKGROUND Continuously infused phenylephrine is frequently used to reduce the incidence of hypotension in women undergoing cesarean section under spinal anesthesia, but less is known about the prophylactic bolus method. We evaluated three prophylactic bolus doses of phenylephrine during low-dose spinal anesthesia for cesarean section. METHODS One-hundred-and-eighty-four patients were randomized to receive 0.9% saline 2mL (Control Group) or phenylephrine 1.0μg/kg (PHE1 Group), 1.5μg/kg (PHE1.5 Group), or 2.0μg/kg (PHE2 Group) immediately after induction of combined spinal-epidural anesthesia. Maternal blood pressure and heart rate were recorded at 1-min intervals until delivery. Hypotension, defined as systolic blood pressure <80% of baseline, was treated with rescue doses of phenylephrine 100μg at 1-min intervals until hypotension resolved. The incidence of nausea, vomiting, bradycardia, and hypertension, as well as Apgar scores and umbilical blood gases, were recorded. RESULTS The incidence of hypotension was 71.7% (33/46) in the Control Group, 68.9% (31/45) in the PHE1 Group, 37.0% (17/46) in the PHE1.5 Group and 45.7% (21/46) in the PHE2 Group (P=0.001). The total rescue dose of phenylephrine was greater in the Control Group than those in the PHE1.5 Group (P<0.05) and PHE2 Group (P<0.05). The incidence of hypertension increased as the dose of prophylactic phenylephrine increased (P<0.001) and was highest in the PHE2 group (37%). Other variables did not differ among the four groups. CONCLUSIONS Under the conditions of this study, prophylactic bolus injection of phenylephrine 1.5μg/kg was a suitable alternative method for reducing the incidence of hypotension during low-dose spinal anesthesia for cesarean section.

Effect of Ethyl Pyruvate on Paclitaxel-Induced Neuropathic Pain in Rats

Background Although paclitaxel is a widely used chemotherapeutic agent for the treatment of solid cancers, side effects such as neuropathic pain lead to poor compliance and discontinuation of the therapy. Ethyl pyruvate (EP) is known to have analgesic effects in several pain models and may inhibit apoptosis. The present study was designed to investigate the analgesic effects of EP on mechanical allodynia and apoptosis in dorsal root ganglion (DRG) cells after paclitaxel administration. Methods Rats were randomly divided into 3 groups: 1) a control group, which received only vehicle; 2) a paclitaxel group, which received paclitaxel; and 3) an EP group, which received EP after paclitaxel administration. Mechanical allodynia was tested before and at 7 and 14 days after final paclitaxel administration. Fourteen days after paclitaxel treatment, DRG apoptosis was determined by activated caspase-3 immunoreactivity (IR). Results Post-treatment with EP did not significantly affect paclitaxel-induced allodynia, although it tended to slightly reduce sensitivities to mechanical stimuli after paclitaxel administration. After paclitaxel administration, an increase in caspase-3 IR in DRG cells was observed, which was co-localized with NF200-positive myelinated neurons. Post-treatment with EP decreased the paclitaxel-induced caspase-3 IR. Paclitaxel administration or post-treatment with EP did not alter the glial fibrillary acidic protein IRs in DRG cells. Conclusions Inhibition of apoptosis in DRG neurons by EP may not be critical in paclitaxel-induced mechanical allodynia.

Unilateral postoperative visual loss in a patient undergoing hip arthroscopy in the supine position: a case report

Micro-emboli have been reported to occur commonly during arthroscopic surgery, which is frequently performed as an orthopedic surgical procedure. We here report a patient who experienced unilateral postoperative visual loss after a hip arthroscopy using irrigation fluid in the supine position without any evidence of external compression to either eye throughout the surgical procedure. Retinal fundoscopy suggested that the patient had central retinal artery occlusion, one of the causes of the postoperative visual loss. This case suggests that arthroscopic surgery may pose a substantial risk for paradoxical air embolism, such as central retinal artery occlusion, and suggests the need to prevent the entry of micro-air bubbles during such a type of surgery.

Clinical Experiences of Transforaminal Balloon Decompression for Patients with Spinal Stenosis

Lumbar spinal stenosis is a commonly treated with epidural injections of local anesthetics and corticosteroids, however, these therapies may relieve leg pain for weeks to months but do not influence functional status. Furthermore, the majority of patients report no substantial symptom change over the repeated treatment. Utilizing balloon catheters, we successfully treated with three patients who complained persistent symptoms despite repeated conventional steroid injections. Our results suggest that transforaminal decompression using a balloon catheter may have potential in the nonsurgical treatment of spinal stenosis by modifying the underlying pathophysiology.

Preconsent video-assisted instruction improves the comprehension and satisfaction in elderly patient visiting pain clinic.

Background Elderly patients visiting pain clinic may be at greater risk of misunderstanding the explanation because of age-related cognitive decline. Video instruction may provide a consistent from of teaching in a visual and realistic manner. We evaluated the effect of educational video on the patient understanding and satisfaction in a group of geriatric patients visiting pain clinic. Methods Ninety two patients aged more than 60 years old who were scheduled for transforaminal epidural block were recruited. After exposure to either video or paper instruction process, each patient was asked 5-item comprehension questions, overall satisfaction and preference question. During follow-up period, number of outpatient referral-line call for further explanation was counted. Results We observed significantly better comprehension in the video education compared with paper instruction (P < 0.001). Patient satisfaction was also higher in the video group (P = 0.015), and patients visiting pain clinic were more preferred video instruction (P < 0.001). Proportion of referral-line call for further explanation were similar (P = 0.302). Conclusions Video approach to instruction process before consent improves treatment comprehension in geriatric patient visiting pain clinic.

Effect of pre-exposure to sevoflurane on the bispectral index in women undergoing Caesarean delivery under general anaesthesia

BACKGROUND Patients undergoing Caesarean delivery under inhalation anaesthesia are at a high risk of awareness, especially in the period before delivery. We assessed the effects of pre-exposure to sevoflurane on the bispectral index (BIS) in the interval before delivery. METHODS Sixty-four patients undergoing elective Caesarean delivery were randomly assigned to receive 1.0-1.1 vol% (control 1) or 1.2-1.3 vol% (control 2) end-tidal sevoflurane, or the same concentrations of end-tidal sevoflurane combined with pre-exposure to 1 vol% sevoflurane for the last 1 min of the preoxygenation period (the preSevo 1 and preSevo 2 groups, respectively). We assessed BIS values, arterial pressure, and heart rate at the time of induction; before intubation; and upon skin incision, uterine incision, and delivery. We also determined the maternal incidence of intraoperative awareness and the neonatal Apgar scores, and conducted umbilical blood gas analysis. RESULTS At skin incision, BIS values were significantly lower in the preSevo 1 group than in the control 1 group [50 (13) vs 72 (8), P<0.001] and in the preSevo 2 group than in the control 2 group [44 (11) vs 67 (10), P<0.001]. The mean BIS values in the preSevo 1 and 2 groups were maintained below 60 in the period before delivery. No other parameter differed among groups, and no patient exhibited intraoperative awareness. CONCLUSIONS Pre-exposure to low concentrations of sevoflurane reduced BIS values in the interval before delivery, suggesting that this approach may reduce the risk of maternal awareness. Clinical Research Information Service (code KCT0000069, http://cris.cdc.go.kr).

An Alternative Approach to Needle Placement in Cervicothoracic Epidural Injections

The use of fluoroscopy guidance together with the loss of resistance technique during epidural injections has been advocated lately; moreover, epidural injections in the absence of fluoroscopic guidance have a high rate of inaccurate needle-tip placement during the injections. However, the approach to the lower cervical and upper thoracic epidural space may be challenging due to its obscure lateral fluoroscopic views from overlying normal tissue structures. In this case, we report an alternative oblique C-arm fluoroscopy guided view approach to supplement the standard anterior-posterior and lateral fluoroscopic views to facilitate successful needle placement and precise anatomical localization of the epidural space.

Malignant hyperthermia and dantrolene sodium

in Korea. The patient was treated with conventional methods including dantrolene, but the patient’s condition became aggravated, requiring the application of an extracorporeal membrane oxygenator (ECMO) to support cardiopulmonary resuscitation [1]. However, if the patient had been treated by prompt administration of dantrolene (i.e., within 20 minutes), we wonder how the patient’s clinical course may have progressed. According to the European Malignant Hyperthermia Group guidelines for management of malignant hyperthermia, at least 36 vials of 20 mg dantrolene should be prepared within 10–15 minutes to effectively treat the condition. However, dantrolene is expensive and has a short life span; thus, routine preparation of dantrolene may not be cost effective [2]. In a previous report, it was noted that many hospitals were not prepared to provide the recommended dose of 36 vials of dantrolene [3]. Although the preparation of 36 vials is not necessarily cost-effective, preparation of the first dose is recommended to prevent serious complications involving reduced mortality, as well as to provide the anesthesiologist with time to prepare the second dose of dantrolene [4]. Therefore, it is necessary to reorganize the current system, in which dantrolene is prepared only in single base hospitals in each region; we propose that the system should be modified to ensure preparation of the first dose of dantrolene such that it can be readily administered in each hospital. We expect that this would enable the first dose of dantrolene to be administered in a much faster time interval than in the current system; this could save patients by reducing associated mortality and morbidity. In addition, patients who express some symptoms and signs that are similar to malignant hyperthermia may not be confirmed as cases of malignant hyperthermia. Therefore, an additional system should be prepared to enable prompt patient transfer to the malignant hyperthermia center; moreover, the caffeine-halothane contracture test and gene test should be available, which can be used for diagnosis and further assistance of patients and their families. This would facilitate prevention of malignant hyperthermia in the future and provide necessary information to the medical providers. We think that a properly equipped malignant hyperthermia center is essential to confirm diagnosis and support affected patients in Korea.

The Antiallodynic Effects of Nefopam Are Mediated by the Adenosine Triphosphate-Sensitive Potassium Channel in a Neuropathic Pain Model.

BACKGROUND: Nefopam hydrochloride is a centrally acting compound that induces antinociceptive and antihyperalgesic properties in neuropathic pain models. Previous reports have shown that activation of adenosine triphosphate (ATP)-sensitive and calcium-activated potassium (KATP and KCa2+) channels has antiallodynic effects in neuropathic pain. In the present study, we evaluated the relationship between potassium channels and nefopam to determine whether the antiallodynic effects of nefopam are mediated by potassium channels in a neuropathic pain model. METHODS: Mechanical allodynia was induced by spinal nerve ligation (SNL) in rats, and the paw withdrawal threshold (PWT) was evaluated by the use of von Frey filaments. Nefopam was administered intraperitoneally before or after SNL. We assessed the relationship between nefopam and intrathecal injection of the KCa2+ channel antagonists apamin and charybdotoxin, and the KATP channel blocker glibenclamide to assess their abilities to reverse the antiallodynic effects of nefopam. In addition, we evaluated whether the KATP channel opener pinacidil had antiallodynic effects and promoted the antiallodynic effects of nefopam. RESULTS: Administration of nefopam before and after SNL induced significant antiallodynic effects (P < .01, respectively), which were significantly reduced by glibenclamide (P < .01). Pinacidil improved the antiallodynic effects of nefopam (P < .01); however, apamin and charybdotoxin had little effects on the antiallodynic properties of nefopam. CONCLUSIONS: The antiallodynic effects of nefopam are increased by a KATP channel agonist and reversed by a KATP channel antagonist. These data suggest that the KATP channel is involved in the antiallodynic effects of nefopam in a neuropathic pain model.