Bong Jin Kang

Minimum effective volume of mepivacaine for ultrasound-guided supraclavicular block.

Background The aim of this study was to estimate the minimum effective volume (MEV) of 1.5% mepivacaine for ultrasound-guided supraclavicular block by placing the needle near the lower trunk of brachial plexus and multiple injections. Methods Thirty patients undergoing forearm and hand surgery received ultrasound-guided supraclavicular block with 1.5% mepivacaine. The initial volume of local anesthetic injected was 24 ml, and local anesthetic volume for the next patient was determined by the response of the previous patient. The next patient received a 3 ml higher volume in the case of the failure of the previous case. If the previous block was successful, the next volume was 3 ml lower. MEV was estimated by the Dixon and Massey up and down method. MEV in 95, 90, and 50% of patients (MEV95, MEV90, and MEV50) were calculated using probit transformation and logistic regression. Results MEV95 of 1.5% mepivacaine was 17 ml (95% confidence interval [CI], 13-42 ml), MEV90 was 15 ml (95% CI, 12-34 ml), and MEV50 was 9 ml (95% CI, 4-12 ml). Twelve patients had a failed block. Three patients received general anesthesia. Nine patients could undergo surgery with sedation only. Only one patient showed hemi-diaphragmatic paresis. Conclusions MEV95 was 17 ml, MEV90 was 15 ml, and MEV50 was 9 ml. However, needle location near the lower trunk of brachial plexus and multiple injections should be performed.

Trigemino-cardiac reflex: occurrence of asystole during trans-sphenoidal adenomectomy: a case report

The trigemino-cardiac reflex has been reported to occur during various craniofacial surgeries or procedures including manipulation of the trigeminal ganglion, tumor resection in the cerebellopontine angle, various facial reconstructions and trans-sphenoidal adenomectomy. Regarding risk factors during trans-sphenoidal adenomectomy, invasiveness closely related to the size of tumor and the degree of manipulation of cavernous sinus wall have been reported. We report the case of a 40-year-old female patient who had a relatively small-sized (< 10 mm) pituitary adenoma. Repetitive asystoles occurred during microscopic trans-sphenoidal operation of the wall of the cavernous sinus, which strongly suggests the importance of careful manipulation of the cavernous sinus wall. In addition to reporting this rare complication of trans-sphenoidal adenomectomy, we reviewed its clinical management by performing a literature search.

Comparison of ultrasound-guided supraclavicular block according to the various volumes of local anesthetic

Background The ultrasound guidance in regional nerve blocks has recently been introduced and gaining popularity. Ultrasound-guided supraclavicular block has many advantages including the higher success rate, faster onset time, and fewer complications. The aim of this study was to examine the clinical data according to the varied volume of local anesthetics in the ultrasound-guided supraclavicular block. Methods One hundred twenty patients were randomized into four groups, according to the local anesthetic volume used: Group 35 (n = 30), Group 30 (n = 30), Group 25 (n = 30), and Group 20 (n = 30). Supraclavicular blocks were performed with 1% mepivacaine 35 ml, 30 ml, 25 ml, and 20 ml, respectively. The success rate, onset time, and complications were checked and evaluated. Results The success rate (66.7%) was lower in Group 20 than that of Group 35 (96.7%) (P < 0.05). The average onset times of Group 35, Group 30, Group 25, and Group 20 were 14.3 ± 6.9 min, 13.6 ± 4.5 min, 16.7 ± 4.6 min, and 16.5 ± 3.7 min, respectively. There were no significant differences. Horners syndrome was higher in Group 35 (P < 0.05). Conclusions In conclusion, we achieved 90% success rate with 30 ml of 1% mepivacaine. Therefore, we suggest 30 ml of local anesthetic volume for ultrasound-guided supraclavicular block.

Myoclonus of ipsilateral upper extremity after ultrasound-guided supraclavicular brachial plexus block with mepivacaine

and analgesic procedures. Myoclonus after regional anesthesia has rarely been reported, but there have been a few reports of myoclonus after a peripheral nerve block. We report a very rare case of myoclonus after a supraclavicular brachial plexus block in a healthy patient with a brief review of literature. A 22-year-old woman (height: 160 cm, body weight: 46 kg, American Society of Anesthesiologists physical status I) was scheduled for a capsular release operation. There was nothing specific in her past medical history. She had previously undergone an uncomplicated left hand procedure under general anesthesia with no anesthesia-related adverse events. Preoperative evaluations were also normal. A supraclavicular brachial plexus block was planned for the anesthesia. Electrocardiography, noninvasive blood pressure, and pulse oximetry were monitored. Before induction of anesthesia, midazolam 2 mg and fentanyl 50 μg were intravenously injected for sedation and pain relief. At the beginning of nerve block, her blood pressure and heart rate were 120/75 mmHg and 65 beats/min. A supraclavicular brachial plexus block was performed under ultrasonographic guidance with a 5 cm standard bevel needle (Profi needle, Shinchang medical Co., Seoul, Korea). We injected 1.5% mepivacaine 40 ml after confirming no aspiration of blood. She did not complain of any severe paresthesia or injection pain during the procedure. Fifteen minutes after procedure, we confirmed successful sensory and motor block of brachial plexus and 5 L/min of oxygen was supplied via facial mask during the operation. An additional 1 mg of midazolam was given intravenously for sedation. The patient was stable during the surgery and the duration of surgical procedure was about 40 minutes. After the surgical procedure, the patient was transferred to a recovery room. One hour after the injection of the local anesthetic, she showed a shivering motion without any chilling sensation. The body temperature was 36.7°C. Meperidine 25 mg was intravenously injected to relieve shivering and 5 L/min of oxygen was supplied via facial mask. However, her shivering continued for about 15 minutes and the patient began to show mild agitation. Thirty minutes after meperidine injection, she showed involuntary movement of left arm, while the other body parts were under control (Video 1). The patient was unable to suppress the movement intentionally but remained conscious and communicated appropriately. She did not complain of pain or any other discomfort and there were no other neurologic symptoms. The driving force for the abnormal movement was from the surrounding muscles of the shoulder with some contribution from the muscles of the elbow joint. We consulted to neurology and the patient was treated with an intravenous injection of midazolam 5 mg but it was not effective. The movement continued while patient was sedated with midazolam. The neurologist examined the patient and about 20 minutes after midazolam injection, lorazepam 4 mg was administered intravenously but it was also not effective. The abnormal movement did Letter to the Editor

Exploring the pros and cons of mechanistic case diagrams for problem-based learning

Purpose Mechanistic case diagram (MCD) was recommended for increasing the depth of understanding of disease, but with few articles on its specific methods. We address the experience of making MCD in the fullest depth to identify the pros and cons of using MCDs in such ways. Methods During problem-based learning, we gave guidelines of MCD for its mechanistic exploration from subcellular processes to clinical features, being laid out in as much detail as possible. To understand the students’ attitudes and depth of study using MCDs, we analyzed the results of a questionnaire in an open format about experiencing MCDs and examined the resulting products. Results Through the responses to questionnaire, we found several favorable outcomes, major of which was deeper insight and comprehensive understanding of disease facilitated by the process of making well-organized diagram. The main disadvantages of these guidelines were the feeling of too much workload and difficulty of finding mechanisms. Students gave suggestions to overcome these problems: cautious reading of comprehensive texts, additional guidance from staff about depth and focus of mechanisms, and cooperative group work. From the analysis of maps, we recognized there should be allowance of diversities in the appearance of maps and many hypothetical connections, which could be related to an insufficient understanding of mechanisms in nature. Conclusion The more detailed an MCD task is, the better students can become acquainted with deep knowledges. However, this advantage should be balanced by the results that there are many ensuing difficulties for the work and deliberate help plans should be prepared.

Effectiveness of milrinone for cardiogenic shock due to massive pulmonary aspiration -a case report-

Pulmonary aspiration of gastric contents is one of the most frightening complications during anesthesia. Although pulmonary aspiration of gastric contents in general surgical patients is not common and resulting long-term morbidity and mortality are rare, severe hypoxemia and other sequelae of pulmonary aspiration continue to be reported. We report a case of massive aspiration of gastric contents during induction of general anesthesia, resulting in cardiac arrest due to severe pulmonary hypertension and myocardial infarction. Sustained cardiac arrest and shock that did not respond the conventional resuscitation was successfully treated using milrinone. The patient was discharged without complications in 20 days.

Paresthesia and sensory deficits on the unilateral leg arising from an unrecognized intramedullary tumor after spinal anesthesia

We report a case of persistent sensory deficits and paresthesia arising from intramedullary cavernous hemangioma after spinal anesthesia, suggesting that practitioners should carefully examine any neurologic abnormalities related to peri-spinal masses. A 36-year-old male underwent an operation for a Mortons neuroma on his left foot. He was active in his daily life, and did not have back pain or any other neurologic signs. Spinal anesthesia was performed at the L3-4 interspace using a 26-gauge spinal needle with a midline approach in the left lateral position with the limb to be operated on in the dependent position. Hyperbaric bupivacaine 11 mg was injected after a free flow of cerebrospinal fluid was observed. He was turned to the supine position, and the level of sensory loss was determined to be T12 by pinprick. The duration of surgery was 40 minutes, and the vital signs and peripheral oxygen saturation were stable. Post-operatively, he was transferred to the post-anesthesia care unit, and 30 minutes later, the sensory level was determined to be below T12. Therefore, he was transferred to the ward. Five hours after spinal anesthesia, sensory function returned to normal in the left leg (operated side), but decreased sensory function and paresthesia persisted in the right leg, the right half of scrotum and the right lower abdomen. He also complained of a burning sensation, which was the most bothersome sign, on the right abdomen. Regarded as transient symptoms after spinal anesthesia, he was discharged on the third day postoperatively. Afterwards, the burning sensation on the right lower abdomen was aggravated gradually, sometimes disturbing his sleep, and the symptoms on the right leg continued without any improvements. Even after one months follow-up, there was no significant improvement. He was administered gabapentin 600 mg and meloxicam 7.5 mg a day. Observing no improvement after three weeks, pregabalin, tramadol, amitryptilline, vitamin B complex, and capsacin cream were administered, to no effect. Dye enhanced MR imaging of the lumbar spine was performed because infection or chemical meningitis was suspected. However there were no specific signs, such as a space-occupying lesion or unusual fluid collection. Sensory and motor nerve conduction studies also showed normal values. A somatosensory evoked potential study showed an increased latency to the right lateral femoral cutaneous nerve stimulation. MR imaging showed a 1 × 1 × 2.3 cm mass located on the postero-left lateral side of spinal cord at the level of T4, and cavernous hemangioma was suspected (Fig. 1). The mass in the thoracic spinal cord was removed 4 months after spinal anesthesia. The histologic features of the mass were consistent with a cavernous hemangioma. Although the surgery was successful, the decreased sensory function has remained without any improvements through one year of follow up. Fig. 1 T2-weighted images on cross section of the upper thoracic intramedullary tumor (T4 level). The mass is located at the postero-left lateral side of spinal cord (arrow head), surrounded by hypoechoic halo signifying clotted blood, macrophages and glial ... In the beginning, we considered that the cause of the patients symptoms was neuritis or a complex regional pain syndrome. Therefore, gabapentin, pregabalin, and a non-steroidal anti-inflammatory agent were administered, which were not effective. We also considered the possibility of neurotoxicity following the injection of heavy bupivacaine, but that idea was discarded because neurotoxicity is presumed to appear bilaterally. On reconsideration, when extensive abnormal neurologic signs, not localized to one or two nerve roots, occurred, a spinal cord problem should have been considered. However, the fact that the patient did not show any motor functional deficits and the thought of having an observation period of the patients illness or responsiveness to drug treatments delayed the diagnosis of a myelopathy. We also consider why symptoms were localized to the right side and motor function was intact. We postulate that the mass was located on the postero-left lateral side of the spinal cord and the mass compressed only the ascending sensory pathway, not the anteriorly located descending motor pathway. There have been few studies regarding the mechanism of myelopathy symptoms, such as paraplegia or paresthesia related to an intramedullary or extramedullary mass after spinal anesthesia [1,2]. Hollis et al. [1] evaluated the results of dural puncture in 50 patients who showed a complete block pattern on the myelogram for the evaluation of various spinal masses, and reported that the incidence of compressive complications following lumbar puncture below a spinal mass was at least 14% (7 of 50 patients). He postulated the main mechanism as follows: With the potentially obstructing mass, there exists a pressure gradient between upper and lower CSF space causing downward force after the dural puncture below the mass. There are a variety of causes of myelopathy related to lumbar puncture for myelography or spinal anesthesia, including metastatic cancer or tuberculosis of the vertebral body, disrupted herniated intervertebral disk, epidural hematoma, epidural abscess, and intramedullary tumor [3,4]. During their natural course, those variable extramedullary or intramedullary masses were associated with not only motor symptoms such as paraparesis but also sensory deficits of extremities. Furthermore, back pain may appear as the first symptom. Therefore, practitioners should pay close attention to clues regarding history and physical examination before central neuraxial blockade. This patient did not show any signs related to cavernous hemangioma preoperatively. Therefore, it was difficult to predict the neurological complications. However, some patients with cavernous hemangiomas may show suspicious signs in the natural clinical courses. Therefore, we suggest that a careful preoperative history and neurologic examination are essential. If there are any suspicious findings, MR imaging of the spine should be considered for further evaluation [5], and when a spinal mass is confirmed, neuraxial blockade should be absolutely avoided and substituted with general anesthesia.

The correlation between the effects of propofol on the auditory brainstem response and the postsynaptic currents of the auditory circuit in brainstem slices in the rat

BACKGROUND Although there have been reports showing the changes of the auditory brainstem response (ABR) waves by propofol, no detailed studies have been done at the level of brainstem auditory circuit. So, we studied the effects of propofol on the postsynaptic currents of the medial nucleus of the trapezoid body (MNTB)-lateral superior olive (LSO) synapses by using the whole cell voltage clamp technique and we compared this data with that obtained by the ABR. METHODS 5 rats at postnatal (P) 15 days were used for the study of the ABR. After inducing deep anesthesia using xylazine 6 mg/kg and ketamine 25 mg/kg, the ABRs were recorded before and after intraperitoneal propofol injection (10 mg/kg) and the effects of propofol on the latencies of the I, III, and V waves and the I-III and III-V interwave intervals were evaluated. Rats that were aged under P11 were used in the voltage clamp experiments. After making brainstem slices, the postsynaptic currents (PSCs) elicited by MNTB stimulation were recorded at the LSO, and the changes of the PSCs by the bath application of propofol (100 microM) were monitored. RESULTS We found small, but statistically significant increases in the latencies of ABR waves III and V and the interwave intervals of I-III and III-V by propofol. However, no significant changes were observed in the glycinergic or glutamatergic PSCs of the MNTB-LSO synpases by the application of propofol (100 microM). CONCLUSIONS Glycinergic or glutamatergic transmission of the MNTB-LSO synapses might not contribute to the propofol-induced changes of the ABR.