Jae Hang Shim

Ultrasound-guided greater occipital nerve block for patients with occipital headache and short term follow up

Background The greater occipital nerve (GON) block has been frequently used for different types of headache, but performed with rough estimates of anatomic landmarks. Our study presents the values of the anatomic parameters and estimates the effectiveness of the ultrasound-guided GON blockade. Methods The GON was detected using ultrasound technique and distance from external occipital protuberance (EOP) to GON, from GON to occipital artery and depth from skin to GON was measured in volunteers. Patients with occipital headache were divided into two groups (ultrasound-guided block: group S, conventional blind block: group B) and GON block was performed. The same parameters were measured on group S and VAS scores were assessed at pretreatment, 1 week and 4 weeks after treatment on both groups. Results The GON had distance of 23.1 ± 3.4 mm (right) and 20.5 ± 2.8 mm (left) from EOP to GON. Its depth below the skin was 6.8 ± 1.5 mm (right) and 7.0 ± 1.3 mm (left). The distance from GON to occipital artery was 1.5 ± 0.6 mm (right) and 1.2 ± 0.6 mm (left) in volunteers. Initial VAS score of group S and group B patients were 6.4 ± 0.2 and 6.5 ± 0.2. VAS score of 4 weeks after injection were 2.3 ± 0.2 on group S and 3.8 ± 0.3 on group B (P = 0.0003). Conclusions The parameters measured in this study should be useful for GON block and ultrasound-guided blockade is likely to be a more effective technique than blind blockade in occipital headache treatment.

The optimal effect-site concentration of remifentanil for lightwand tracheal intubation during propofol induction without muscle relaxation

STUDY OBJECTIVE To determine the most suitable effect-site concentration of remifentanil during lightwand intubation when administered with a target-controlled infusion (TCI) of propofol at 4.0 μg/mL without neuromuscular blockade. DESIGN Prospective study using a modified Dixons up-and-down method. SETTING Operating room of an academic hospital. PATIENTS 28 ASA physical status 1 and 2 patients, aged 18-65 years, scheduled for minor elective surgery. INTERVENTIONS Anesthesia was induced by TCI propofol effect-site concentration to 4.0 μg/mL, and the dose of remifentanil given to each patient was determined by the response of the previously tested patient using 0.2 ng/mL as a step size. The first patient was tested at a target effect-site concentration of 4.0 ng/mL of remifentanil. If intubation was successful, the remifentanil dose was decreased by 0.2 ng/mL; if it failed, the remifentanil dose was increased by 0.2 ng/mL. Successful intubation was defined as excellent or good intubating conditions. MEASUREMENTS AND MAIN RESULTS The remifentanil effect-site concentration was measured. The optimal effect-site concentration of remifentanil for lightwand tracheal intubation during propofol induction using 2% propofol target effect-site concentration to 4 μg/mL was 2.16 ± 0.19 ng/mL. From probit analysis, the effect-site concentration of remifentanil required for successful lightwand intubation in 50% (EC50) and 95% (EC95) of adults was 2.11 ng/mL (95% CI 1.16-2.37 ng/mL) and 2.44 ng/mL (95% CI 2.20-3.79 ng/mL), respectively. CONCLUSION A remifentanil effect-site concentration of 2.16 ± 0.19 ng/mL given before a propofol effect-site concentration of 4 μg/mL allowed lightwand intubation without muscle relaxant.

Minimum current requirement for confirming the localization of an epiradicular catheter placement

Background Based on the necessity to confirm the epiradicular catheter misplacement, epiradicular threshold current for the confirmation of catheter tip localization is required. Methods Thirty-four adult patients with low extremity radiating pain were to receive epiradicular catheterization at the lumbosacral level. The epidural space was accessed percutaneously in cranial to caudal direction. A metal coil-reinforced epidural catheter was inserted and advanced caudolaterally toward the target neural foramen until the catheter tip was located below the bisection of pedicle. The electrical stimulation was performed after catheter placement in epidural and epiradicular space. Using the constant current nerve stimulator, the stimulating current was increased from 0 to 5 mA (pulse width of 0.3 ms; frequency of 2 Hz) until adequate motor contraction was evident. The threshold current for motor response with epidural space (EDmA) and epiradicular space (ERmA) placement were recorded upon electrical stimulation. In addition, the threshold charge for motor response with epidural (EDnC) and epiradicular (ERnC) placement were recorded. Results Of 34 catheters intentionally placed in the epiradicular space, ERmA was 0.53 ± 0.48 mA. The ERnC was significantly lower than EDnC (P < 0.05). The EDmA and ERmA were below 1 mA in 3 patients and above 1 mA in 4 patients, respectively. Conclusions We conclude that, threshold current for motor response seems to be lower for epiradicular compared with epidural placement, although we were not able to directly investigate the epidural threshold current. The threshold current of epiradicular space overlap that in the epidural space.

Fluoroscopic analysis of lumbar epidural contrast spread after retrograde interlaminar ventral epidural injection (RIVEI).

Background Retrograde interlaminar ventral epidural injection (RIVEI) may hypothetically be more effective if the catheter is placed at the ventrocaudal aspect of the exiting nerve. We tested that hypothesis by measuring ventral and dorsal epidural contrast flow during RIVEI. Methods To perform RIVEI, a 17 G Tuohy needle was inserted to access the epidural space. A 19 G epidural catheter was inserted and advanced through the needle, passing in a caudal direction to the lower aspect of the contralateral pedicle. Fluoroscopic images were recorded at 1.5 ml increments of contrast. Based on the images of contrast dispersal, the extent of contrast spreading was assessed in 82 patients. Results All 82 patients (100%) injected with 3.0 ml contrast medium demonstrated ventral epidural spreading. Mean spreading level from the catheter tip was 2.21 ± 0.93 with 3.0 ml of contrast. Spreading to the superior aspect of the supra-adjacent intervertebral disc was observed in 67/82 (81.7%) of RIVEIs with 3.0 ml of contrast injected into the ventral epidural space. We found that 3.0 ml of contrast reached the inferior aspect of the infra-adjacent intervertebral disc in 95.1% (78/82) of RIVEIs performed. Conclusions Our findings imply that a one-level RIVEI may be sufficient in situations where a two-level injection would currently be used.

Spinal cord stimulation: panacea for incurable diseases?

A spinal cord stimulator is usually used as an electro-modulator for pain treatment. Shealy et al. [1] first reported the use of a spinal cord stimulator in an elderly male suffering with terminal bronchogenic carcinoma and right-sided chest pain in 1967. Since then, spinal cord stimulation (SCS) has been applied to many disease entities, such as neuropathic pain, failed back surgery syndrome, complex regional pain syndrome, and ischemic peripheral vascular disease [2-4]. The indications for SCS have been extended to include intractable angina pain, interstitial cystitis, intractable pain, headache, and non-painrelated applications such as refractory congestive heart failure, intractable spasticity, or treatment of cerebral vasospasm after subarachnoid hemorrhage [5-9]. SCS systems are composed of three components: leads/electrodes, a generator/power source, and a programmer/controller [5]. Leads can be divided into percutaneous leads and paddle leads. Small-sized rechargeable implanted batteries are becoming increasingly common. An electrical current is applied to the dorsal columns, creating a tingling sensation in the dermatomes whose afferent fibers traverse the regions being stimulated. The physician can control the degree, range of current, pulse width, and rate of the stimulation wave to optimize pain control. In this issue of the Korean Journal of Anesthesiology, Ryu et al. [10] report the effect of cervical SCS for treatment of digit ulcers in a patient with Buerger’s disease. Thromboangiitis obliterans is a type of segmental inflammatory vasculitis asso ciated with severe pain and ulcers, which involves the small or medium-sized arteries and veins. Treatment of this painful ulcer is difficult and often involves amputation of the affected limb. This case report suggests that cervical SCS is a good choice for reducing pain and healing of an ulcer in patients with vasculitis. There are some reports of the effectiveness of SCS for patients with Raynaud’s disease and Buerger’s disease [11-13]. Cook et al. [14] reported using electronic stimulation of spinal nerves and the dorsal root in patients with a vascular disease of the limbs. Since then, SCS has been successfully used to treat atherosclerotic and vasospastic peripheral arterial disease. SCS improves microcirculation by inhibiting sympathetic vasoconstriction. SCS reduces pain in Buerger’s disease by stimulating the secretion of a number of inhibitory neurotransmitters and promoting the secretion of gamma aminobutyric acid, substance P, and serotonin at the spinal nerve dorsal horn [15,16]. Wolter and Kieselbach [17] reported the long-term outcomes of patients with cervical SCS. Treatment indications included patients with causalgia, cervicobrachialgia, complex regional pain syndrome, phantom pain, and Raynaud’s syndrome [18]. Pain reduction and paresthesia coverage were effective in almost all patients, and treatment satisfaction was high. No severe complications, such as neurological deficits or infection, were reported. They concluded that cervical SCS appears to be a safe and efficacious treatment option for upper limb neuropathic pain. Nevertheless, SCS has some disadvantages. The procedure for implanting SCS is invasive, so it is associated with complications such as infection, bleeding, and dural puncture [19]. The effectiveness of SCS is limited, and regular checks and continuous follow-ups are needed. Furthermore, SCS is expensive because of the limited medical insurance coverage in Korea. However, SCS is cost effective as compared with conservative management alone in cases with medical insurance coverage. Advances in SCS technology and understanding of the

Is it necessary to use prophylactics for preventing PONV

Postoperative nausea and vomiting (PONV) are common and distressing postsurgical symptoms [1] which continue to be a significant concern for anesthesiologists. PONV occurs in 20% to 30% of the general population underwent surgery and in up to 70% to 80% of high risk patients [2,3]. PONV is a complex physiologic phenomenon involving multiple neurophysiologic pathways with both central and peripheral receptor mechanisms. A variety of factors have been associated with an increased incidence of postoperative nausea and vomiting. The most frequently described patient-specific risk factors for PONV are female gender, non-smokers, types of surgery such as laparoscopic surgery [4,5] or head and neck surgery, previous history of PONV or motion sickness, and use of intra-operative or postoperative opioids [3]. Postoperative analgesia with opioids is associated with an incidence of PONV of over 30% [6]. Thyroidectomy is also associated with a relatively high incidence of PONV. The incidence of PONV after thyroidectomy has a reporting rate of 60-76% according to previous study [7]. PONV after thyroidectomy surgery might be the main source of discomfort, and it may be perceived as the most unpleasant aspect of postoperative recovery [8]. Being able to identify patient-specific risk factors should help clinicians determine appropriate prophylactic treatment for PONV. Many clinicians have used different types of anti-emetics such as anticholinergic drug, 5-hydroxytryptamine 3 (5-HT3) antagonist or NK-1 antagonist for the treatment of PONV. Ramosetron is a newly developed 5-HT3 receptors antagonist with a more potent and longer receptor antagonizing effect compared with other 5-HT3 receptors antagonists [9]. In this issue of the Korean Journal of Anesthesiology, Lee et al. [10] report on the antiemetic effect of ramosetron with thyroidectomy for PONV. This clinical trial demonstrates the preventative effect of ramosetron for PONV in women undergoing total thyroidectomy with propofol-based total intravenous anesthesia (TIVA). The authors concluded that ramosetron was effective at reducing the incidence and severity of postoperative nausea in women that underwent total thyroidectomy with propofol-based TIVA during first 6 hours postoperatively. Nevertheless there are some debatable points in this paper. The incidences of postoperative nausea in the control and the ramosetron groups were 29% and 12% during first 6 postoperative hours respectively. From a statistical point of view, ramosetron is obviously more effective than control during first 6 postoperative hours (P = 0.029). But there were no differences between ramosetron and control (saline) after 6 hours postoperatively. Also postoperative vomiting was not different all time periods on both groups. The incidence of PONV on the control group was not that high and widely different compared to the ramosetron group in this study as the authors mentioned. While many practitioners believe that 5-HT3 antagonists are relatively safe medications, it is uncertain whether the antiemetic effects of 5-HT3 antagonists are better than inexpensive drugs such as droperidol or metoclopramide clinically. There is also uncertainty about benefit of ramosetron in patients undergoing TIVA. Cost-effective management is often referred to as an important medical issue. Recently, medical budgets are not sufficient for medical services of all patients in our country. Therefore, we need to be concerned about reduction of medical costs. In Korea, ramosetron (approximately US

Is ultrasound-guided procedure entirely reliable?

55 for 0.3 mg) is much more expensive than other commonly used antiemetics, such as metoclopramide. Many risk scoring systems for predicting PONV have been mentioned at present [3]. An evaluation of these risk factors allows clinicians to appropriately plan for prophylaxis and treatment of PONV. Eberhart suggests the use of simplified algorithms that could lead to a benefit for a larger proportion of patients [11]. Clearly, such a risk score-adapted preventive strategy for PONV may be viewed as an efficient method for PONV treatment. The first strategy in reducing the incidence of postoperative nausea and vomiting is to reduce the baseline risk factors for each patient. Patients with a low risk of PONV generally do not require prophylactic medication. Patients at moderate or high risk should receive antiemetic therapy with high cost-effective drugs. Additionally, inexpensive and comprehensive multimodal managements for preventing PONV should be considered perioperatively. The use of propofol and the avoidance of nitrous oxide add to reductions of the incidence of PONV [12,13]. Other simple methods such as maintaining adequate hydration, minimizing the use of opioid analgesics for preventing postoperative pain in high risk patients, and P-6 acupoint stimulation [14] are also available.

Limitations of spinal cord stimulation for pain management

and can be used as the sole anesthesia for upper or lower extremity surgery. Especially peripheral nerve blocks have been used for upper extremity surgery as an important anesthetic technique from the past. The upper extremity blocks include supraclavicular, infraclavicular, interscalene, and axillary plexus block. The interscalene block and brachial plexus block (BPB) were first described in the early 1900s [1]. Nerve blocks including upper extremity blockade have been usually performed by reference to anatomical landmarks. For improved accuracy and effectiveness, the nerve stimulator technique was introduced in the late 1980s, while the ultrasound (US)-guided technique started in the early 1990s [2]. The use of US for nerve blockade has increased with the development of high resolution equipment, increased portability, and decreased costs. The US-guided technique has several advantages, including ease of performance, visualization of soft tissues and real-time needle advancement, no exposure to radiation, and observation of the spread of the injected local anesthetic [3]. A systematic review summarized the evidences for the superior onset, quality, and duration of block for US guidance versus other techniques for nerve localization [4]. According to this review, US guidance confers a modest improvement in block onset and the quality of peripheral nerve blocks, especially for the lower extremity. Sonographic visualization of the peripheral nerve and surrounding anatomy can provide valuable information for diagnostic purposes and procedure enhancement [5]. US-guided techniques for visualizing the needle tip and observing the spread of injected local anesthetic can reduce the risk of side effects, such as accidental intravascular injection and trauma to the surrounding tissues. US-guided technique also reduces the anesthetic volume required to produce an effective block [6]. However, there are some limits to US imaging, such as the inability to visualize deep structures, a narrow imaging window, artifacts, operator-dependent imaging performance, and difficulty of mastery. In this issue of the Korean Journal of Anesthesiology, two cases of complications associated with US procedures are introduced. Kang et al. [7] reported a neurologic complication after US-guided supraclavicular BPB and Beh et al. [8] described a pulmonary complication induced by phrenic nerve block after interscalene BPB. Upper extremity blocks are known to cause side effects, such as nerve damage, local anesthesia toxicity due to intravascular injection, pneumothorax, and diaphragm dysfunction. A recent update report by the American Society of Regional Anesthesia and Pain Medicine concluded that US-guided technique reduces the incidence and intensity of hemidiaphragmatic paresis, but has no significant effect on the incidence of postoperative neurological symptoms. US guidance reduces the risk of local anesthesia toxicity and may also reduce the frequency of pneumothorax, but training in visualization of the needle is required [6,9]. The development of US-guided techniques and advance in equipment open a new horizon in regional anesthesia and pain management. US is a rapidly developing area of technology and some of the newer modalities are discussed. US has been applied to peripheral musculoskeletal and axial structures, including by caudal and interlaminar epidural injections, cervical and lumbar facet injections, medial branch blocks, and sacroiliac joint injections [10,11]. New procedures and equipment have also been attempted, such as a perineural catheter [12] and US-guided percutaneous cryoneurolysis [13]. Further technological developments should allow for more accurate, higher resolution, and smaller sized US machine. Nevertheless, we should not place our complete trust in US-guided nerve block, because the accuEditorial

Comparison of the GlideScope and the McGrath method using vascular forceps and a tube exchanger in cases of simulated difficult airway intubation

As mentioned before [1], the spinal cord stimulation is very useful treatment modality for intractable pain. The spinal cord stimulator (SCS) has been applied for the treatment of pain associated with many different disease entities, including intractable pain, headache, and angina pain. It has also been applied for non-pain-related conditions such as congestive heart failure, ischemic peripheral vascular disease, interstitial cystitis, intractable spasticity, and cerebral vasospasm after subarachnoid hemorrhage [2,3,4,5,6]. In a previous issue of the Korean journal of anesthesiology, Lee et al. [7] described the pain management during a procedure for permanent spinal cord stimulation with a cylindrical type lead insertion. They mentioned that implantation of a permanent SCS system is painful and intolerable in some patients. Therefore they attempted to perform the procedure under epidural anesthesia. SCS systems are composed of three components: leads/electrodes, a generator/power source, and a programmer/controller [8]. The leads can be divided into percutaneous leads and paddle leads. When pain physicians use percutaneous cylindrical type leads, procedure is usually performed under local anesthetic infiltration. However, actually many patients complain of pain or discomfort during SCS device implantation because they have existing severe pain that make worse. This case report suggests that epidural anesthesia is a good choice for reducing pain and ensuring safety during establishment of permanent spinal cord stimulation with percutaneous cylindrical type lead insertion. Many pain physicians, myself included, believe that the spinal cord stimulation is a lamp of hope for patients with intractable pain. However, some limitations confound our endeavors. Mekhail et al. [9] reported indications and complications of SCS in 707 cases with discussion. The reported complication rate ranges from 30 to 40%. The lead migration rate is 22.6%, the lead connection failure rate is 9.5%, and lead breakage rate is 6.0%. Lead migration complication is more frequent with percutaneous than paddle-type electrodes [3,5]. Infection was reported in 4.5% of patients and pain at the generator site in 12.0% of patients. Other complications include bleeding, paresthesia, and dural puncture [2,4,6]. Hardware related problems, such as lead failure, migration, and device malfunction, are more common than infection [10]. Complications may be avoided or at least diminished by performing a proper and strict aseptic surgical technique as well as regular checks and continuous follow-up [5]. Hayek et al. [11] reported the long-term implant survival rate and complications of SCS. The complication rate was 34.6%, and hardware related complications were the most common type of complications among 234 cases. The revision and explantation rates were both 23.9%. The most common reason for explantation was loss of the therapeutic effect. Although the rate of serious complications was low, the rate of overall complications remained relatively high in that study. The authors concluded that a greater effort is needed to decrease complication rates in the future, which will increase patient satisfaction and decrease medical costs. Other problems involve the perioperative evaluation and management of patients with spinal cord stimulator [12]. Performing magnetic resonance imaging (MRI) with SCS implanted patients is harmful and restricted because of heating of SCS and injuring the patient. MRI-safe SCS device is important for patients with spinal origin pain, particularly for management of postlaminectomy syndrome. Monopolar electrocautery is also generally not recommended for patients with SCS because of the risk of thermal injury to the tissue in contact with the SCS. Therefore, bipolar electrocautery is recommended when cautery is necessary. The most important factor for minimizing risks regarding SCS implanted patients is increasing physician awareness. Young et al. [13] reported the management of pregnant women with SCS implantation. Seven patients underwent implantation of SCS before becoming pregnant. Data on these patients before, during, and after labor were collected. Four general anesthetics and three neuraxial anesthetics were administered for cesarean delivery. All infants and mothers were healthy after delivery. They mentioned that interventional pain physicians have to consider future pregnancy as an issue in treating young women with complex regional pain syndrome. Some patients with SCS have comorbid diseases such as cardiovascular problems. The incidence of patients with cardiac disease has recently increased, and numerous implantable cardioverter-defibrillators (ICD) are now being used to treat potentially life-threatening cardiac arrhythmias. Chaiban et al. [14] reported electromagnetic interaction between SCS and lifesaving ICD. Although there were some limitations in their study, they demonstrated that there was no interaction between the two devices at various settings. However, physicians need to confirm the safety and interaction between SCS and ICD during implantation of the SCS in patient who already have an ICD device. Many engineers and machinery companies are focusing much effort on developing new equipment. The multi-channel device with multi-polar small sized leads, integrated accelerometer, embedded gyroscope, sensing feedback technology and MRI safe device may promise to increase efficacy and decrease limitations and device-related complications of SCS in the near future [15]. Bioengineering, including advancement of SCS technology and mechanism, should help to liberate patients from pains and aches.