Byeongcheol Lee

Background and Objectives: Accurate prediction of surgical duration is essential for efficient operating room management. Spine surgery frequently shows discrepancies between estimated and actual surgical duration, which can disrupt surgical scheduling and resource allocation. The aim of this study was to develop and compare machine learning (ML) algorithms for predicting spine surgery duration and identify the most effective approach. Materials and Methods: Electronic medical records of 3376 patients who underwent spine surgery were retrospectively analyzed at a single center. The dataset was divided into training (80%, n = 2700) and internal test (20%, n = 676) sets using stratified random sampling based on surgical duration quintiles. To match the intended use at the time of operating room scheduling, four models (Random Forest, XGBoost, multilayer perceptron [MLP], and weighted least squares [WLS] regression) were developed using only predictors available at scheduling and evaluated on the independent internal test set; a full-information model that additionally included intraoperatively recorded variables was examined for comparison. Results: XGBoost demonstrated the best predictive performance, achieving a mean squared error (MSE) of 3014.6 min² (equivalent to a root mean squared error [RMSE] of 54.9 min; 95% CI for MSE, 2558.3–3556.0) and an R² of 0.622 (95% CI, 0.566–0.675). The other ML models showed comparable performance, whereas WLS regression performed less favorably; the full-information model performed equivalently (R² 0.622). Compared with surgeon-estimated duration alone, XGBoost reduced mean absolute error by approximately 20 min (paired ΔMAE −20.1 min; 95% CI, −23.7 to −16.5) and improved prediction accuracy within 60 min by 14.0 percentage points. SHapley Additive exPlanations (SHAP) analysis identified surgeon identity as the most influential predictor across all models (24.7–41.9%), followed by procedure type and surgeon-estimated duration. Conclusions: Machine learning models substantially improved prediction of spine surgery duration compared with conventional approaches, with XGBoost showing the highest predictive accuracy. Surgeon identity emerged as the most important predictor of surgical duration. Implementation of such models may improve operating room scheduling efficiency and resource allocation but requires prospective evaluation of clinical and workflow outcomes.

For perioperative hypothermia prevention, a heated, humidified breathing circuit equipped with a fluid-warming unit inside the inspiratory limb has been developed. We report a ventilation difficulty caused by an obstructed heated breathing circuit. Cotton surrounding the hot wire, temperature sensor, and fluid tubing in the distal inspiratory limb was irregularly thicker than that of a normal circuit and nearly blocked the lumen. Despite carrying out routine checks on the anesthesia workstation preoperatively, we failed to make a prediagnosis by omitting the flow test after changing the circuit. This case puts emphasis on a routine flow test with a meticulous examination of the heated breathing circuit before every procedure.

Objective: Rare coexistence of disease or pathologyBackground: Herpes zoster caused by the reactivation of latent varicella-zoster virus is thought to result from the waning of specific cell-mediated immunity. Scrub typhus, an acute infectious disease caused by Orientia tsutsugamushi, affects multiple organs and is characterized by microangiopathies that result in significant vascular leakage and subsequent end-organ injury. Very few cases of reactivation of the varicella-zoster virus following scrub typhus occurrence have been reported. Furthermore, no previous studies have directly investigated whether Orientia tsutsugamushi infection is a potential risk factor for herpes zoster.Case Report: We present the case of a 64-year-old woman without a previous illness who simultaneously developed herpes zoster of the thoracic dermatome and scrub typhus. Clinical symptoms of scrub typhus appeared during the treatment course for herpes zoster symptoms. Based on positive virus antibody test results, the patient was diagnosed with scrub typhus. This is a unique case of reactivation of the varicella-zoster virus that occurred during a silent incubation period for scrub typhus.Conclusions: This report indicates the possibility of reactivation of latent varicella-zoster virus following Orientia tsutsuga-mushi infection, although the relationship between the 2 remains undetermined. Physicians should be aware that scrub typhus might be a potential determinant of varicella-zoster virus reactivation.

Background and Objectives: Evidence regarding the prevalence of neuropathic pain in patients with cervical radicular pain is limited. This study aimed to investigate the prevalence of neuropathic pain components in patients with cervical radicular pain using established screening tools and identify the relationship between neuropathic pain components and clinical factors. Materials and Methods: Data from 103 patients (aged ≥ 20 years) with cervical radicular pain who visited our pain clinic were analyzed retrospectively. Demographic characteristics, history of neck surgery, pain intensity using numeric rating score, dominant pain site, duration of symptoms, and neck disability index were assessed. The prevalence of neuropathic pain components was defined according to the Douleur Neuropathique 4 questions and painDETECT questionnaire tools. Patient characteristics were compared using the chi-square test or Fisher’s exact test for categorical variables and the independent t-test or Mann–Whitney U test for continuous variables. The correlation between neck disability index and other variables was analyzed using Pearson’s correlation coefficient. Results: Of the 103 patients, 29 (28.1%) had neuropathic pain components. The neck disability index was significantly higher (p < 0.001) for patients in the neuropathic pain group (23.79 ± 6.35) than that in the non- neuropathic pain group (18.43 ± 7.68). The Douleur Neuropathique 4 questions (r = 0.221, p < 0.025) and painDETECT questionnaire (r = 0.368, p < 0.001) scores positively correlated with the neck disability index score. Conclusions: The prevalence of neuropathic pain components in patients with cervical radicular pain was low. The patients in our study showed a strong correlation between functional deterioration and their neuropathic pain screening score. This study may be useful in understanding the characteristics of cervical radicular pain.

Although echocardiography is widely used for preoperative cardiac risk evaluation, few studies have analyzed the effect of performing preoperative echocardiography on intraoperative anesthetic management and postoperative outcomes. We investigated the effect of performing echocardiography on intraoperative anesthetic management and postoperative outcomes in patients with cardiovascular risk. We retrospectively evaluated patients who had undergone major abdominal surgery and satisfied 2 or more of the following criteria: hypertension, diabetes mellitus, age ≥70 years, and previous cardiac disease. Patients were categorized into a group in which preoperative echocardiography was performed (echo) and a group in which it was not (non-echo). The primary outcomes were postoperative 30-day mortality and incidence of cardiovascular complications. Secondary outcomes were length of hospital stay, intraoperative incidence of hypotension, use of vasopressors, and findings on intraoperative invasive hemodynamic monitoring. There were no differences in 30-day mortality, incidence of postoperative cardiovascular complications, length of hospital stay, and intraoperative events between the groups. Only the incidence of cardiac output monitoring was lower in the echo group than in the non-echo group (59.6% vs 73.9%). Preoperative echocardiography does not affect postoperative outcomes, but it has the potential to affect intraoperative anesthetic management such as invasive hemodynamic monitoring during surgery.

Background: Strabismus surgery and the use of opioid are risk factors of postoperative vomiting. We evaluated whether there is a dose-dependent effect of remifentanil on the incidence of postoperative vomiting. Methods: Sixty pediatric patients who were scheduled for strabismus surgery were enrolled. Patients were randomly divided into three groups; Group H (high-dose remifentanil group), Group L (low-dose remifentanil group), and Group C (control group). After endotracheal intubation, patients in the Group H and L received an intravenous bolus dose of remifentanil of 1.0 μg/kg and 0.5 μg/kg over 2 min, respectively. Group H and L patients received a continuous infusion of remifentanil (0.1 μg/kg/min) during the surgery. The patients in Group C did not have any dose of remifentanil. Intravenous fentanyl (1 µg/kg) was administered to the patients for postoperative pain control. Results: The primary outcome was a difference of the incidence of postoperative vomiting within 24 hours after surgery. There was no significant difference in incidence of postoperative vomiting between three groups. The degree of emergence agitation and postoperative pain did not show any significant difference between three groups. Conclusions: The intraoperative administration of remifentanil did not show dose-dependent effect on postoperative vomiting in pediatric strabismus surgery.

Introduction: Leriche syndrome is an aortoiliac occlusive disease caused by atherosclerotic occlusion. We report a case of Leriche syndrome with a fracture that was suspected as complex regional pain syndrome (CRPS), as the post-traumatic pain gradually worsened in the form of excruciating neuropathic pain. Case Report: A 52-year-old woman with a history of hypertension was referred to the Department of Pain Medicine from a local orthopedic clinic because of suspected CRPS for excruciating neuropathic pain for one month. She complained of gait dysfunction and severe pain in the right foot following an incident of trauma with the right first toe. The average pain intensity assessed using the visual analog scale (VAS) was 90 (0: no pain, 100: the worst pain imaginable), and the neuropathic pain was evident as a score of 6/10 on Douleur neuropathique 4. Allodynia, hyperalgesia, blue discoloration of the skin, asymmetric temperature change (1.38 °C), and edematous soft tissue changes were observed. Ultrasonography showed a chip fracture in the first distal phalanx of the right first toe. The diagnosis was most probably CRPS type I according to the Budapest research criteria for CRPS. However, multiple pain management techniques were insufficient in controlling the symptoms. A month and a half later, an ankle-brachial index score of less than 0.4 suggested severe peripheral artery disease. Computed tomography angiography showed total occlusion between the infrarenal abdominal aorta and the bilateral common iliac arteries. Therefore, she underwent aortic-bifemoral bypass surgery with a diagnosis of Leriche syndrome. Three months after the surgery, the average pain intensity was graded as 10 on the VAS (0–100), the color of the skin of the right first toe improved and no gait dysfunction was observed. Conclusion: A chip fracture in a region with insufficient blood flow could manifest as excruciating neuropathic pain in Leriche syndrome.

Background and Objectives: The harmonization of recovery of consciousness and muscular function is important in emergence from anesthesia. Even if muscular function is recovered, tracheal extubation without adequate recovery of consciousness may increase the risk of respiratory complications. In particular, upper airway obstruction is one of the common respiratory complications and can sometimes be fatal. However, the association between the timing of sugammadex administration and the upper airway obstruction that can occur during awakening from anesthesia has rarely been studied. Materials and Methods: The medical records of 456 patients who had surgery under general endotracheal anesthesia (GETA) at the Haeundae Paik Hospital between October 2017 and July 2018 and who received intravenous sugammadex to reverse rocuronium-induced neuromuscular blockade were analyzed. The correlations between bispectral index (BIS) and minimum alveolar concentration (MAC) at the time of sugammadex administration, the incidence of complications, and the time to tracheal extubation were analyzed to investigate how different timings of sugammadex administration affected upper airway obstruction after tracheal extubation. Conclusions: The effect of BIS and the duration from anesthetic discontinuation to sugammadex administration on upper airway obstruction was not statistically significant. However, the odds ratio of complication rates with MAC < 0.3 compared with MAC ≥ 0.3 was 0.40 (95% confidence interval 0.20 to 0.81, p = 0.011), showing a statistically significant increase in risk with MAC ≥ 0.3 for upper airway obstruction.

Pathology of the lumbar spine and hip joint can commonly coexist in the elderly. Anterior and lateral leg pain as symptoms of hip osteoarthritis and spinal stenosis can closely resemble each other, with only subtle differences in both history and physical examinations. It is not easy to identify the origin of this kind of hip pain. The possibility of hip osteoarthritis should not be underestimated, as this could lead to an incorrect diagnosis and inappropriate spinal surgery. We report the case of a 54-year-old female with chronic right anterior and lateral leg pain who did not respond to repeated spinal blocks based on lumbar MRI, but in whom hip osteoarthritis was considered since severe atrophy of the ipsilateral psoas muscle was identified. We suggest that severe psoas muscle atrophy can be a clinical clue to identify hip osteoarthritis and is related to lower extremity pain, even if there is a coexisting lumbar spine pathology.

Background and objectives: The purpose of this study was to compare and to analyze contrast spread patterns between the paramedian and midline approaches to cervical interlaminar epidural injection (CIEI). Materials and Methods: We retrospectively enrolled 84 CIEI cases that had been performed for unilateral cervical spinal pain from April 2019 to April 2020. After 3 mL of contrast had been injected into the epidural space, fluoroscopic images were obtained. The CIEI was divided into a midline (Group M, n = 42) and a paramedian (Group P, n = 42) approach by anteroposterior imaging. The P Group was classified into a more medial (Group Pm, n = 26) and a more lateral (Group Pl, n = 16) group. Using ImageJ on an anteroposterior image, we assessed the grayscale brightness ratio of the ipsilateral or contralateral side of the vertebral body as well as the intervertebral disc space one level just above the needle location. We identified the dispersion of contrast into the ventral epidural space. Results: The grayscale brightness ratio was significantly higher in Group P than in Group M (p < 0.001). The incidence of ventral epidural spread in Group M was 57.1% versus 88.1% in Group P, which was significantly different (p = 0.001). Conclusions: The fluoroscopic CIEI finding in the paramedian approach predominantly showed an excellent delivery of the injectate to the ipsilateral side in comparison to the contralateral side. This showed a greater advantage in delivery toward ventral epidural space as compared to the midline approach.