Obesity and anesthetic pharmacology: simulation of target-controlled infusion models of propofol and remifentanil / 대한마취과학회지

The prevalence of obesity is increasing, resulting in an increase in the number of surgeries performed to treat obesity and diseases induced by obesity. The associated comorbidities as well as the pharmacokinetic and pharmacodynamic changes that occur in obese patients make it difficult to control the appropriate dose of anesthetic agents. Factors that affect pharmacokinetic changes include the increase in adipose tissue, lean body weight, extracellular fluid, and cardiac output associated with obesity. These physiological and body compositional changes cause changes in the pharmacokinetic and pharmacodynamic parameters. The increased central volume of distribution and alterations in the clearance of drugs affect the plasma concentration of propofol and remifentanil in the obese population. Additionally, obesity can affect pharmacodynamic properties, such as the 50% of maximal effective concentration and the effect-site equilibration rate constant (ke0). Conducting a simulation of target-controlled infusions based on pharmacokinetic and pharmacodynamic models that include patients that are obese can help clinicians better understand the pharmacokinetic and pharmacodynamic changes of anesthetic drugs associated with this population.

The principles of presenting statistical results: Table / 대한마취과학회지

General medical journals such as the Korean Journal of Anesthesiology (KJA) receive numerous manuscripts every year. However, reviewers have noticed that the tables presented in various manuscripts have great diversity in their appearance, resulting in difficulties in the review and publication process. It might be due to the lack of clear written instructions regarding reporting of statistical results for authors. Therefore, the present article aims to briefly outline reporting methods for several table types, which are commonly used to present statistical results. We hope this article will serve as a guideline for reviewers as well as for authors, who wish to submit a manuscript to the KJA.

The principles of presenting statistical results: Table / 대한마취과학회지

General medical journals such as the Korean Journal of Anesthesiology (KJA) receive numerous manuscripts every year. However, reviewers have noticed that the tables presented in various manuscripts have great diversity in their appearance, resulting in difficulties in the review and publication process. It might be due to the lack of clear written instructions regarding reporting of statistical results for authors. Therefore, the present article aims to briefly outline reporting methods for several table types, which are commonly used to present statistical results. We hope this article will serve as a guideline for reviewers as well as for authors, who wish to submit a manuscript to the KJA.

Minimal clinically important difference of commonly used patient-reported outcome measures in total knee arthroplasty: review of terminologies, methods and proposed values

Purpose@#The aim of this article was to highlight various terminologies and methods of calculation of minimal clinically important difference (MCID) and summarize MCID values of frequently used patient-reported outcome measures (PROMs) evaluating total knee arthroplasty (TKA). @*Materials and methods@#PubMed and EMBASE databases were searched through May 2019. Of 71 articles identified, 18 articles matched and underwent a comprehensive analysis for terminologies used to indicate clinical significance, method of calculation, and reported MCID values. @*Results@#MCID was the most common terminology (67% studies) and anchor-based methods were most commonly employed (67% studies) to calculate it. The analytical methods used to calculate and the estimated values of MCID for clinical use are highly variable. MCID values reported for WOMAC scores are 20.5 to 36.0, 17.6 to 33.0 and 12.9 to 25.0 for pain, function and stiffness sub-scales, respectively, and 4.7 to 10.0 for OKS. @*Conclusion@#There was lack of standardization in the methodology employed to calculate MCID in the available studies. MCID values reported in this review could be used for patients undergoing TKA, although caution is advised in their interpretation and application.

Tips for troublesome sample-size calculation / 대한마취과학회지

Properly set sample size is one of the important factors for scientific and persuasive research. The sample size that can guarantee both clinically significant differences and adequate power in the phenomena of interest to the investigator, without causing excessive financial or medical considerations, will always be the object of concern. In this paper, we reviewed the essential factors for sample size calculation. We described the primary endpoints that are the main concern of the study and the basis for calculating sample size, the statistics used to analyze the primary endpoints, type I error and power, the effect size and the rationale. It also included a method of calculating the adjusted sample size considering the dropout rate inevitably occurring during the research. Finally, examples regarding sample size calculation that are appropriately and incorrectly described in the published papers are presented with explanations.

Results of Decompression Alone in Patients with Lumbar Spinal Stenosis and Degenerative Spondylolisthesis: A Minimum 5-Year Follow-up

Background@#Surgical treatment consisting of decompression and fusion is generally known to produce good clinical results for lumbar spinal stenosis with degenerative spondylolisthesis. However, the clinical outcome of decompression alone, without fusion, remains unclear, and long-term follow-up results are scarce. This study aimed to retrospectively analyze the 5-year clinical results of decompression only in patients with lumbar spinal stenosis and degenerative spondylolisthesis. @*Methods@#Among the patients diagnosed as having lumbar spinal stenosis with degenerative spondylolisthesis, 36 patients who underwent decompression without fusion and were followed up for minimum 5 years were included in this study. The average follow-up period was 7.2 years, and the mean age of patients was 63.2 years. Visual analog scale (VAS) score and Oswestry disability index (ODI) were investigated pre- and postoperatively, and also radiologic displacement and instability were measured. In addition, patients who needed fusion or redecompression at the decompression site postoperatively were also investigated. @*Results@#VAS score and ODI improved from an average of 7.8 points and 57 points preoperatively, respectively, to 1.4 points and 19 points at 5 years postoperatively, respectively. The degree of radiologic displacement increased from an average of 5.1 mm preoperatively to 6.4 mm at the final follow-up. Radiological instability was detected in five patients. Two patients (9.5%) required fusion. @*Conclusions@#The long-term follow-up results revealed that satisfactory clinical outcomes were obtained with decompression alone, without fusion, for patients with lumbar spinal stenosis and degenerative spondylolisthesis.

Comparison of the Clinical Outcomes of an Ultrasound-Guided and C-Arm Guided Cervical Nerve Root Block / 대한정형외과학회잡지

PURPOSE@#This paper compares the clinical outcomes of patients who were treated with a cervical nerve block by ultrasound and C-arm and reports the complication.@*MATERIALS AND METHODS@#A total of 97 patients were treated with an ultrasound-guided nerve root block from May 1, 2015 to February 8, 2018. On the other hand, 94 patients were treated with a C-arm guided nerve root block. The consequences of the cervical pain and the radiating pain before and after the procedures were reviewed using the verbal numeric rating scale (VNRS). In addition, the complications related to the procedures from the daily notes from the chart were inspected.@*RESULTS@#Sixty-six cases out of 97 cases of ultrasound-guided nerve root block were enrolled in the study. The average age of the patients was 57 years, including 41 males and 25 females. Seventy seven out of 94 cases by a C-arm guided root block were included in the study. The average age of the patients was 55 years, including 40 males and 37 females. Before the nerve root block, the mean numeric rating pain scale (NRS) of the cervical pain in ultrasound-guided block decreased from 5.4 points to 2.7 points at three weeks and 1.4 points at six weeks (p=0.0023, p<0.001), and 3.1 points in the C-arm (p<0.001, p<0.001) at three weeks and 1.5 points at six weeks (p<0.001, p<0.001). In the case of radiating pain, the mean NRS in the ultrasound-guided nerve root block group improved from 6.3 points after the procedure to 2.8 points at three weeks and 1.5 points at six weeks (p<0.001, p<0.001). In the C-arm guided nerve root block group, the NRS improved from 7.4 points after the procedure to 3.3 points at three weeks and 1.9 points at six weeks. In the case of complications, Horner's syndrome and propriospinal myoclonus were observed in one case of C-arm guided block group.@*CONCLUSION@#The clinical results of the patients who underwent ultrasound-guided cervical nerve root block were not significantly different from those who underwent a C-arm guided cervical nerve root block.

Predictive Factors for the Short-Term Efficacy of Epidural Injections in Lumbar Disc Herniation Treatment

Objectives@#The purpose of this study was to analyze several factors affecting the efficacy of epidural steroid injections as a nonoperative treatment modality in lumbar disc herniation patients.Summary of Literature Review: Despite several studies, the normal course of intervertebral disc herniation is not fully understood, and the optimal timing of surgery is unclear. @*Methods@#From January 2017 to April 2019, among outpatients in our hospital, 64 patients diagnosed with 3-4 or 4-5 single-level lumbar disc herniation and followed up for at least 6 weeks were included. Epidural steroid injection was performed in all patients during their 1-week admission. Symptoms improved in 36 patients (group 1) and persisted or recurred in 28 patients (group 2), who were finally treated surgically. Demographic factors, magnetic resonance imaging findings, and clinical assessments were analyzed. @*Results@#The only demographic factor with a significant difference between groups was symptom duration. In magnetic resonance imaging, significant differences were found in disc sequestration and the degree of the herniated disc. At 6 weeks after the injection, significant differences were found between the 2 groups in visual analog scale scores and the Korean version of the Oswestry Disability Index. @*Conclusions@#Several factors must be considered when treating patients with lumbar disc herniation. Of note, longer symptom duration was found to be associated with a lower effectiveness of conservative treatment. The effects of treatment could also be influenced by the disc form and the degree of disc herniation.

Predictive Factors for the Short-Term Efficacy of Epidural Injections in Lumbar Disc Herniation Treatment

Objectives@#The purpose of this study was to analyze several factors affecting the efficacy of epidural steroid injections as a nonoperative treatment modality in lumbar disc herniation patients.Summary of Literature Review: Despite several studies, the normal course of intervertebral disc herniation is not fully understood, and the optimal timing of surgery is unclear. @*Methods@#From January 2017 to April 2019, among outpatients in our hospital, 64 patients diagnosed with 3-4 or 4-5 single-level lumbar disc herniation and followed up for at least 6 weeks were included. Epidural steroid injection was performed in all patients during their 1-week admission. Symptoms improved in 36 patients (group 1) and persisted or recurred in 28 patients (group 2), who were finally treated surgically. Demographic factors, magnetic resonance imaging findings, and clinical assessments were analyzed. @*Results@#The only demographic factor with a significant difference between groups was symptom duration. In magnetic resonance imaging, significant differences were found in disc sequestration and the degree of the herniated disc. At 6 weeks after the injection, significant differences were found between the 2 groups in visual analog scale scores and the Korean version of the Oswestry Disability Index. @*Conclusions@#Several factors must be considered when treating patients with lumbar disc herniation. Of note, longer symptom duration was found to be associated with a lower effectiveness of conservative treatment. The effects of treatment could also be influenced by the disc form and the degree of disc herniation.

Use of an Epidural Steroid Sponge for Postoperative Pain Control in Lumbar Discectomy / 대한척추외과학회지

STUDY DESIGN: Retrospective study. OBJECTIVES: This study was conducted to evaluate the effects of using an epidural steroid sponge for postoperative pain control in lumbar discectomy. SUMMARY OF LITERATURE REVIEW: There are many methods to control postoperative pain after lumbar discectomy, including opioid analgesics, epidural catheters, and epidural steroid Gelfoam sponges. MATERIALS AND METHODS: A total of 72 patients who underwent surgery between March 2011 and February 2014 were enrolled. Their average age was 54 years (range, 24–82 years). In group A (35 patients), Gelfoam was inserted after being soaked with a solution of 2% lidocaine (400 mg/20 mL; 1 vial) and dexamethasone (5 mg/mL; 1 ampoule). In group B (37 patients), it was inserted after soaking with normal saline. Postoperative pain was assessed by visual analogue scale (VAS) scores. Pain above 5 points was controlled by a narcotic analgesic agent, and the duration and number of postoperative interventions, the period of time before walking after the operation, and the period until the date of discharge after surgery were assessed and compared. The Mann-Whitney U test was used as a nonparametric method. P-values less than 0.05 were considered to indicate statistical significance. RESULTS: In group A, 15 patients did not require analgesics on the day of surgery. In 20 patients, no analgesics were needed on postoperative day (POD) 1. In group B, 8 patients on the day of surgery and 13 patients on POD 1 did not require analgesics. In group A, 26 patients were able to walk on the day of surgery, and all patients were able to walk on POD 1. In group B, 19 patients was able to walk on the day of surgery and all patients were able to walk on POD 1. The mean number of hospital days before discharge was 6.3 in group A and 8.2 in group B. CONCLUSIONS: By continuously releasing low doses of steroids into the epidural space, this technique provided satisfactory results for postoperative pain control.

More about the basic assumptions of t-test: normality and sample size / 대한마취과학회지

Most parametric tests start with the basic assumption on the distribution of populations. The conditions required to conduct the t-test include the measured values in ratio scale or interval scale, simple random extraction, normal distribution of data, appropriate sample size, and homogeneity of variance. The normality test is a kind of hypothesis test which has Type I and II errors, similar to the other hypothesis tests. It means that the sample size must influence the power of the normality test and its reliability. It is hard to find an established sample size for satisfying the power of the normality test. In the current article, the relationships between normality, power, and sample size were discussed. As the sample size decreased in the normality test, sufficient power was not guaranteed even with the same significance level. In the independent t-test, the change in power according to sample size and sample size ratio between groups was observed. When the sample size of one group was fixed and that of another group increased, power increased to some extent. However, it was not more efficient than increasing the sample sizes of both groups equally. To ensure the power in the normality test, sufficient sample size is required. The power is maximized when the sample size ratio between two groups is 1 : 1.

Assessment of P values for demographic data in randomized controlled trials / 대한마취과학회지

In a large number of randomized controlled trials, researchers provide P values for demographic data, which are commonly reported in table 1 of the article for the purpose of emphasizing the lack of differences between or among groups. As such, the authors intend to demonstrate that statistically insignificant P values in the demographic data confirm that group randomization was adequately performed. However, statistically insignificant P values do not necessarily reflect successful randomization. It is more important to rigorously establish a plan for statistical analysis during the design and planning stage of the study, and to consider whether any of the variables included in the demographic data could potentially affect the research results. If a researcher rigorously designed and planned a study, and performed it accordingly, the conclusions drawn from the results would not be influenced by P values, regardless of whether they were significant. In contrasts, imbalanced variables could affect the results after variance controlling, even though whole study process are well planned and executed. In this situation, the researcher can provide results with both the initial method and a second stage of analysis including such variables. Otherwise, for brief conclusions, it would be pointless to report P values in a table simply listing baseline data of the participants.

Successful removal of permanent spinal cord stimulators in patients with complex regional pain syndrome after complete relief of pain

BACKGROUND: It is uncommon for patients who have received a permanent implant to remove the spinal cord stimulator (SCS) after discontinuation of medication in complex regional pain syndrome (CRPS) due to their completely painless state. This study evaluated CRPS patients who successfully removed their SCSs. METHODS: This 10-year retrospective study was performed on patients who had received the permanent implantation of an SCS and had removed it 6 months after discontinuation of stimulation, while halting all medications for neuropathic pain. Age, sex, duration of implantation, site and type of CRPS, and their return to work were compared between the removal and non-removal groups. RESULTS: Five (12.5%, M/F = 4/1) of 40 patients (M/F = 33/7) successfully removed the permanent implant. The mean age was younger in the removal group (27.2 ± 6.4 vs. 43.5 ± 10.7 years, P < 0.01). The mean duration of implantation in the removal group was 34.4 ± 18.2 months. Two of 15 patients (13.3%) and 3 of 25 patients (12%) who had upper and lower extremity pain, respectively, had removed the implant. The implants could be removed in 5 of 27 patients (18.5%) with CRPS type 1 (P < 0.01). All 5 patients (100%) who removed their SCS returned to work, while only 5 of 35 (14.3%) in the non-removal group did (P < 0.01). CONCLUSIONS: Even though this study had limited data, younger patients with CRPS type 1 could remove their SCSs within a 5-year period and return to work with complete pain relief.

Stem cell therapy in pain medicine / 대한통증학회지

Stem cells are attracting attention as a key element in future medicine, satisfying the desire to live a healthier life with the possibility that they can regenerate tissue damaged or degenerated by disease or aging. Stem cells are defined as undifferentiated cells that have the ability to replicate and differentiate themselves into various tissues cells. Stem cells, commonly encountered in clinical or preclinical stages, are largely classified into embryonic, adult, and induced pluripotent stem cells. Recently, stem cell transplantation has been frequently applied to the treatment of pain as an alternative or promising approach for the treatment of severe osteoarthritis, neuropathic pain, and intractable musculoskeletal pain which do not respond to conventional medicine. The main idea of applying stem cells to neuropathic pain is based on the ability of stem cells to release neurotrophic factors, along with providing a cellular source for replacing the injured neural cells, making them ideal candidates for modulating and possibly reversing intractable neuropathic pain. Even though various differentiation capacities of stem cells are reported, there is not enough knowledge and technique to control the differentiation into desired tissues in vivo. Even though the use of stem cells is still in the very early stages of clinical use and raises complicated ethical problems, the future of stem cells therapies is very bright with the help of accumulating evidence and technology.

Corrigendum: The Usefulness of Selective Nerve Root Block for Failed Back Surgery Syndrome / 대한정형외과학회잡지

There are some errors in the published article. The authors would like to make corrections in the original version of the article.

More about the basic assumptions of t-test: normality and sample size / 대한마취과학회지

Most parametric tests start with the basic assumption on the distribution of populations. The conditions required to conduct the t-test include the measured values in ratio scale or interval scale, simple random extraction, normal distribution of data, appropriate sample size, and homogeneity of variance. The normality test is a kind of hypothesis test which has Type I and II errors, similar to the other hypothesis tests. It means that the sample size must influence the power of the normality test and its reliability. It is hard to find an established sample size for satisfying the power of the normality test. In the current article, the relationships between normality, power, and sample size were discussed. As the sample size decreased in the normality test, sufficient power was not guaranteed even with the same significance level. In the independent t-test, the change in power according to sample size and sample size ratio between groups was observed. When the sample size of one group was fixed and that of another group increased, power increased to some extent. However, it was not more efficient than increasing the sample sizes of both groups equally. To ensure the power in the normality test, sufficient sample size is required. The power is maximized when the sample size ratio between two groups is 1 : 1.

Assessment of P values for demographic data in randomized controlled trials / 대한마취과학회지

In a large number of randomized controlled trials, researchers provide P values for demographic data, which are commonly reported in table 1 of the article for the purpose of emphasizing the lack of differences between or among groups. As such, the authors intend to demonstrate that statistically insignificant P values in the demographic data confirm that group randomization was adequately performed. However, statistically insignificant P values do not necessarily reflect successful randomization. It is more important to rigorously establish a plan for statistical analysis during the design and planning stage of the study, and to consider whether any of the variables included in the demographic data could potentially affect the research results. If a researcher rigorously designed and planned a study, and performed it accordingly, the conclusions drawn from the results would not be influenced by P values, regardless of whether they were significant. In contrasts, imbalanced variables could affect the results after variance controlling, even though whole study process are well planned and executed. In this situation, the researcher can provide results with both the initial method and a second stage of analysis including such variables. Otherwise, for brief conclusions, it would be pointless to report P values in a table simply listing baseline data of the participants.

Use of an Epidural Steroid Sponge for Postoperative Pain Control in Lumbar Discectomy

OBJECTIVES@#This study was conducted to evaluate the effects of using an epidural steroid sponge for postoperative pain control in lumbar discectomy.SUMMARY OF LITERATURE REVIEW: There are many methods to control postoperative pain after lumbar discectomy, including opioid analgesics, epidural catheters, and epidural steroid Gelfoam sponges.@*MATERIALS AND METHODS@#A total of 72 patients who underwent surgery between March 2011 and February 2014 were enrolled. Their average age was 54 years (range, 24–82 years). In group A (35 patients), Gelfoam was inserted after being soaked with a solution of 2% lidocaine (400 mg/20 mL; 1 vial) and dexamethasone (5 mg/mL; 1 ampoule). In group B (37 patients), it was inserted after soaking with normal saline. Postoperative pain was assessed by visual analogue scale (VAS) scores. Pain above 5 points was controlled by a narcotic analgesic agent, and the duration and number of postoperative interventions, the period of time before walking after the operation, and the period until the date of discharge after surgery were assessed and compared. The Mann-Whitney U test was used as a nonparametric method. P-values less than 0.05 were considered to indicate statistical significance.@*RESULTS@#In group A, 15 patients did not require analgesics on the day of surgery. In 20 patients, no analgesics were needed on postoperative day (POD) 1. In group B, 8 patients on the day of surgery and 13 patients on POD 1 did not require analgesics. In group A, 26 patients were able to walk on the day of surgery, and all patients were able to walk on POD 1. In group B, 19 patients was able to walk on the day of surgery and all patients were able to walk on POD 1. The mean number of hospital days before discharge was 6.3 in group A and 8.2 in group B.@*CONCLUSIONS@#By continuously releasing low doses of steroids into the epidural space, this technique provided satisfactory results for postoperative pain control.

Treatment Options of Osteoporotic Vertebral Compression Fractures

This paper reviews previous studies on the treatment of osteoporotic vertebral compression fractures in elderly patients to determine what factors should be considered for successful treatment. In osteoporotic vertebral compression fractures, the primary treatment is conservative treatments. Other treatments include osteoporosis treatment, pain control, orthosis, and physical therapy. Recently, percutaneous catheterization or balloon plasty is performed for rapid pain recovery and early ambulation. Percutaneous catheterization or balloon posterior plasty is effective in reducing pain and improving the activity ability. Surgical treatment should be considered in cases of nonunion or osteonecrosis, dent, deformation, and spinal cord compression after conservative treatment has failed. In surgical treatment, posterior spinal fixation and vertebroplasty are more advantageous in terms of the amount of bleeding, operation time compared to the anterior approach, but the most appropriate method should be selected through the patient's condition and understanding of each surgical method.

Erratum: Radiological Results of the Double-Balloon Inflation Technique during Kyphoplasty / 대한척추외과학회지

Correction of funding statement.