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Preprints are preliminary research reports that have not yet been peer-reviewed. They have been widely adopted to promote the timely dissemination of research across many scientific fields. In August 1991, Paul Ginsparg launched an electronic bulletin board intended to serve a few hundred colleagues working in a subfield of theoretical high-energy physics, thus launching arXiv, the first and largest preprint platform. Additional preprint servers have since been implemented in different academic fields, such as BioRxiv (2013, Biology; www.biorxiv. org) and medRxiv (2019, Health Science; www.medrxiv.org). While preprint availability has made valuable research resources accessible to the general public, thus bridging the gap between academic and non-academic audiences, it has also facilitated the spread of unsupported conclusions through various media channels. Issues surrounding the preprint policies of a journal must be addressed, ultimately, by editors and include the acceptance of preprint manuscripts, allowing the citation of preprints, maintaining a double-blind peer review process, changes to the preprint’s content and authors’ list, scoop priorities, commenting on preprints, and preventing the influence of social media. Editors must be able to deal with these issues adequately, to maintain the scientific integrity of their journal. In this review, the history, current status, and strengths and weaknesses of preprints as well as ongoing concerns regarding journal articles with preprints are discussed. An optimal approach to preprints is suggested for editorial board members, authors, and researchers. [ABSTRACT FROM AUTHOR]

Background: Herpes zoster (HZ) is one of the most common cutaneous adverse reactions associated with the coronavirus disease 2019 (COVID-19) vaccine and has been widely reported. This study aimed to evaluate HZ following COVID-19 vaccination from the viewpoint of pain management. Methods: A retrospective study was conducted on 42 patients with HZ who visited the pain clinic between August 2021 and October 2021. Medical records were reviewed to compare pain severity, treatment methods, treatment duration, and incidence rate of postherpetic neuralgia (PHN) in patients who received COVID-19 vaccination within 6 weeks prior to developing symptoms compared with other patients with HZ. Results: Fourteen patients developed HZ within 6 weeks after vaccination and were significantly younger than the other HZ groups. There were no significant differences in the frequency of prodromal pain, location of pain, pain severity, treatment methods, treatment duration, or incidence of PHN compared with the other HZ groups. Conclusions: COVID-19 vaccination-related HZ showed clinical features similar to those of the other HZ. [ABSTRACT FROM AUTHOR]

Background: Although spinal cord stimulation (SCS) can be a treatment option for intractable postherpetic neuralgia (PHN), obtaining proper stimulation at the thoracic dermatome is difficult. Dorsal root ganglion (DRG) stimulation may be an effective treatment for patients with insufficient efficacy in SCS only. Case: A 54-year-old male with intractable PHN was referred to our clinic. Pain was localized to the distribution of the T1–3 dermatomes. SCS trial was conducted, and lead was placed within the epidural space over the C6–T1 level; however, the stimulation was inadequate for his pain site. Therefore, another lead was placed within the left T1 and T2 DRG for trial, and T1 DRG stimulation provided adequate stimulation. T1 DRG stimulation and SCS could cover the entire pain site with paresthesia, and his pain was decreased by over 50%. Conclusions: DRG stimulation combined with SCS may be a good treatment option for intractable thoracic PHN. [ABSTRACT FROM AUTHOR]

Background: In some patients with neuropathic pain (NP), such as complex regional pain syndrome (CRPS), itching rather than pain is the main symptom making diagnosis and treatment difficult. Case: We report a case of a 23-year-old male with a history of hypoxic brain damage who presented with pruritus of the left foot and ankle. His left foot was fractured, and he underwent surgery 6 months previously. After the operation and cast application, he developed uncontrolled pruritus, swelling, sweating, and flushing of the left foot skin with limping. On examination, he showed well-known features of CRPS without pain. He was diagnosed with an atypical CRPS with neuropathic itching (NI). With treatment modalities used for NP and CRPS, his pruritus subsided gradually, and the his ankle mobility improved. Conclusions: Unexplained itching can be the main symptom in some CRPS patients. Treatment according to NP can improve symptoms of NI in CRPS patients. [ABSTRACT FROM AUTHOR]

Background: Gasserian ganglion radiofrequency thermoablation is a good treatment option for the management of pain in trigeminal neuralgia. We report a case in which the patient of trigeminal neuralgia combined with anterior cerebral artery aneurysm was treated successfully by gasserian ganglion thermoablation without any complication. Case: An 85-year-old female presenting with electric shock like sensation in the gum and molar teeth was diagnosed as trigeminal neuralgia. Carbamazepine medication and trigeminal nerve blockade relieved her pain partially, but severe side effects of carbamazepine occurred. Magnetic resonance angiography of the brain showed saccular aneurysm in inferior aspect of the anterior communicating artery. Gasserian ganglion thermoablation under sedation anesthesia using nicardipine was performed carefully without any rupture of the cerebral aneurysm. Conclusions: Gasserian ganglion thermoablation could be performed safely in a patient with cerebral aneurysm without any inadvertent event. [ABSTRACT FROM AUTHOR]

Background: Nasotracheal intubation is generally performed for intraoral surgery. Case: A 34-year-old female patient who underwent orthognathic surgery exhibited repeated endotracheal tube cuff tears during nasotracheal intubation. After intubation, leaks developed, and torn endotracheal cuff was observed in the removed endotracheal tube. Subsequently, re-intubation through the same nasal cavity was performed immediately, but leakage from the torn endotracheal tube cuff was re-observed. A leakage test of the extubated tube revealed air bubbles and leaks near the tube cuff due to the tear. Nasotracheal intubation was performed through the other nasal cavity, and there were no leakage findings or abnormalities. During the course of the surgery, the surgeon noticed that the orthodontic micro-implant deposited in the mid-tube cavity was exposed to the nasal cavity. Conclusions: We aimed to emphasize caution and discuss the possibility that orthodontic micro-implants that are not confirmed during preoperative evaluation may cause repeated endotracheal tube cuff tears. [ABSTRACT FROM AUTHOR]

Background: The OptiscopeTM and the backward, upward, rightward pressure (BURP) maneuver are widely used in clinical practice because the BURP maneuver facilitates intubation by improving visualization of the larynx. However, the effect of the BURP maneuver is unclear when using the OptiscopeTM. Therefore, we retrospectively investigated the effect of the BURP maneuver on intubation using the OptiscopeTM. Methods: Sixty-eight patients intubated with the OptiscopeTM were enrolled. We used the BURP maneuver in Group A (n = 33) and the conventional maneuver (which does not use the BURP maneuver) in Group B (n = 35). BURP application status was a binary variable representing whether the BURP maneuver was used during the intubation. A multiple linear regression analysis was performed to assess the effects of the BURP application status on intubation time controlling for body mass index, preoperative dental injury status, obstructive sleep apnea history, thyromental distance, sternomental distance, interincisor distance, history of neck rotation restriction, and Mallampati classification. Results: There was no difference in the intubation time between the two groups. According to the regression model (R2 = 0.308, P = 0.007), the BURP maneuver (Group A) decreased the intubation time by 6.089 seconds (95% confidence interval 1.303–10.875, P = 0.014) compared to Group B. Conclusions: The BURP maneuver reduced intubation time when using the OptiscopeTM. [ABSTRACT FROM AUTHOR]

Background: Epidural block placement in pediatric patients is technically challenging for anesthesiologists. The use of ultrasound (US) for the placement of an epidural catheter has shown promise. We compared landmark-guided and US-guided lumbar or lower thoracic epidural needle placement in pediatric patients. Methods: This prospective, randomized, comparative trial involved children aged 1–6 years who underwent abdominal and thoracic surgeries. Forty-five children were randomly divided into two groups using a computer-generated random number table, and group allocation was performed by the sealed opaque method into either landmark-guided (group LT) or real- time ultrasound-guided (group UT) epidural placement. The primary outcome was a comparison of the procedure time (excluding US probe preparation). Secondary outcomes were the number of attempts (re-insertion of the needle), bone contacts, needle redirection, skin-to-epidural distance using the US in both groups, success rate, and complications. Results: The median (interquartile range) time to reach epidural space was 105.5 (297.0) seconds in group LT and 143.0 (150) seconds in group UT (P = 0.407). While the first attempt success rate was higher in the UT group (87.0% in UT vs. 40.9% in LT; P = 0.004), the number of bone contacts, needle redirections, and procedure-related complications were significantly lower. Conclusions: The use of US significantly reduced needle redirection, number of attempts, bone contact, and complications. There was no statistically significant difference in the time to access the epidural space between the US and landmark technique groups. [ABSTRACT FROM AUTHOR]

Background: Generally, lactate levels > 2 mmol/L represent hyperlactatemia, whereas lactic acidosis is often defined as lactate > 4 mmol/L. Although hyperlactatemia is common finding in liver transplant (LT) candidates, association between lactate and organ failures with Acute-on-chronic Liver Failure (ACLF) is poorly studied. We searched the important variables for pre-LT hyperlactatemia and examined the impact of preoperative hyperlactatemia on early mortality after LT. Methods: A total of 2,002 patients from LT registry between January 2008 and February 2019 were analyzed. Six organ failures (liver, kidney, brain, coagulation, circulation, and lung) were defined by criteria of EASL-CLIF ACLF Consortium. Variable importance of preoperative hyperlactatemia was examined by machine learning using random survival forest (RSF). Kaplan-Meier Survival curve analysis was performed to assess 90-day mortality. Results: Median lactate level was 1.9 mmol/L (interquartile range: 1.4, 2.4 mmol/L) and 107 (5.3%) patients showed > 4.0 mmol/L. RSF analysis revealed that the four most important variables for hyperlactatemia were MELD score, circulatory failure, hemoglobin, and respiratory failure. The 30-day and 90-day mortality rates were 2.7% and 5.1%, whereas patients with lactate > 4.0 mmol/L showed increased rate of 15.0% and 19.6%, respectively. Conclusions: About 50% and 5% of LT candidates showed pre-LT hyperlactatemia of > 2.0 mmol/L and > 4.0 mmol/L, respectively. Pre-LT lactate > 4.0 mmol/L was associated with increased early post-LT mortality. Our results suggest that future study of correcting modifiable risk factors may play a role in preventing hyperlactatemia and lowering early mortality after LT. [ABSTRACT FROM AUTHOR]

Thoracic epidural analgesia is known to have superior perioperative pain control over intravenous opioid analgesia in open abdominal surgery and is an essential enhanced recovery after surgery component in major abdominal surgeries. Recently, the ultrasound-guided thoracic epidural catheter placement (TECP) technique has drawn attention as an alternative for the traditional landmark palpation-based TECP or fluoroscopic-guided TECP technique due to the equipment’s improvement and increased popularity. However, only a small number of studies have introduced the advantages and usefulness of ultrasound-guided TECP. Moreover, a certain level of ultrasound-guided in-plane technique is required to perform this technique. Thus, to apply ultrasound-guided TECP correctly and reduce the likelihood of side effects and complications, the practitioner must have a thorough understanding of the anatomical region, optimal block positioning, device selection, and management. In this technical review, the authors have compared the advantages and disadvantages of ultrasound- guided TECP to traditional techniques and described its technical aspects from patient positioning, ultrasound probe selection and scanning, needle insertion under ultrasound guidance, and successful thoracic epidural catheter insertion confirmation through ultrasound imaging. Additionally, the recommended epidural catheter tip placement level with the extent of its injectate epidural spread is further described in this review in reference to a recent prospective study published by the authors. [ABSTRACT FROM AUTHOR]

Background: Dynamic preload indices may predict fluid responsiveness in end-stage liver disease. However, their usefulness in patients with altered vascular compliance is uncertain. This study is the first to evaluate whether dynamic indices can reliably predict fluid responsiveness in patients undergoing liver transplantation with a high femoral-to-radial arterial pressure gradient (PG). Methods: Eighty liver transplant recipients were retrospectively categorized as having a normal (n = 56) or high (n = 24, difference in systolic pressure ≥ 10 mmHg and/or mean pressure ≥ 5 mmHg) femoral-to-radial arterial PG, measured immediately after radial and femoral arterial cannulation. The ability of dynamic preload indices (stroke volume variation, pulse pressure variation [PPV], pleth variability index) to predict fluid responsiveness was assessed before the surgery. Fluid replacement of 500 ml of crystalloid solution was performed over 15 min. Fluid responsiveness was defined as ≥ 15% increase in the stroke volume index. The area under the receiver-operating characteristic curve (AUC) indicated the prediction of fluid responsiveness. Results: Fourteen patients in the normal, and eight in the high PG group were fluid responders. The AUCs for PPV in the normal, high PG groups and total patients were 0.702 (95% confidence interval [CI] 0.553–0.851, P = 0.008), 0.633 (95% CI 0.384–0.881, P = 0.295) and 0.667 (95% CI 0.537–0.798, P = 0.012), respectively. No other index predicted fluid responsiveness. Conclusions: PPV can be used as a dynamic index of fluid responsiveness in patients with end-stage liver disease but not in patients with altered vascular compliance. [ABSTRACT FROM AUTHOR]

Background: Awake craniotomy is a well-tolerated procedure for the resection of brain tumors residing within or close to the eloquent cortical areas. Monitored anesthesia care (MAC) is a dominant anesthetic approach for awake craniotomy; however, it is associated with inherent challenges such as desaturation and hypercapnia, which may lead to various complications. The prevention of respiratory insufficiency is important for successful awake craniotomy. As measures to avoid respiratory depression, the use of high-flow nasal cannula (HFNC) can improve patient oxygenation and monitor the monitoring the oxygen reserve index (ORi) can detect hypoxia earlier. Case: We report two cases of awake craniotomy with MAC using HFNC and ORi. We adjusted the fraction of inspired oxygen of the HFNC according to the ORi level. The patient underwent successful awake craniotomy without a desaturation event or additional airway intervention. Conclusions: Combined HFNC and ORi monitoring may provide adequate oxygen reserves in patients undergoing awake craniotomy. [ABSTRACT FROM AUTHOR]

Background: The clinical efficacy of preoperative 2D-echocardiographic assessment of pulmonary arterial pressure (PAP) has not been evaluated fully in liver transplantation (LT) recipients. Methods: From October 2010 to February 2017, a total of 344 LT recipients who underwent preoperative 2D-echocardiography and intraoperative right heart catheterization (RHC) was enrolled and stratified according to etiology, disease progression, and clinical setting. The correlation of right ventricular systolic pressure (RVSP) on preoperative 2D-echocardiography with mean and systolic PAP on intraoperative RHC was evaluated, and the predictive value of RVSP > 50 mmHg to identify mean PAP > 35 mmHg was estimated. Results: In the overall population, significant but weak correlations were observed (R = 0.27; P < 0.001 for systolic PAP, R = 0.24; P < 0.001 for mean PAP). The positive and negative predictive values of RVSP > 50 mmHg identifying mean PAP > 35 mmHg were 37.5% and 49.9%, respectively. In the subgroup analyses, correlations were not significant in recipients of deceased donor type LT (R = 0.129; P = 0.224 for systolic PAP, R = 0.163; P = 0.126 for mean PAP) or in recipients with poorly controlled ascites (R = 0.215; P = 0.072 for systolic PAP, R = 0.21; P = 0.079 for mean PAP). Conclusions: In LT recipients, the correlation between RVSP on preoperative 2D-echocardiography and PAP on intraoperative RHC was weak; thus, preoperative 2D-echocardiography might not be the optimal tool for predicting intraoperative PAP. In LT candidates at risk of pulmonary hypertension, RHC should be considered. [ABSTRACT FROM AUTHOR]

The prevalence of obese parturients is increasing worldwide. This review describes safe analgesic techniques for labor and anesthetic management during cesarean sections in obese parturients. The epidural analgesic technique is the best way to provide good pain relief during the labor phase and can be easily converted to a surgical anesthetic condition. However, the insertion of the epidural catheter in obese parturients is technically more difficult compared to that in non-obese parturients. The distance from the skin to the epidural space increases in proportion to the body mass index (BMI): 4.4 cm in mothers of normal weight and 7.5 cm in mothers with BMI 50 and above. Neuraxial blocks are the ideal anesthetic methods and gold standard techniques for cesarean section in pregnant women with obesity. Single-shot spinal anesthesia is the most common type of anesthesia used for cesarean sections. The advantage of single-shot spinal anesthesia is a dense-sufficient block of rapid onset. A combined spinal-epidural (CSE) anesthetic technique is also recommended as an attractive alternative method. In obese parturients, the operation time can be longer than expected, and therefore, the CSE technique provides the advantage of rapid onset and intense block for prolonged operation with postoperative pain control. The risk of postoperative complications is very high in obese parturients. Therefore, detailed communication of the parturient’s medical condition and the details of surgery and anesthesia between the anesthesiologist and obstetrician is important prior to cesarean section in obese pregnant women. [ABSTRACT FROM AUTHOR]

Ex-utero intrapartum treatment (EXIT) is a method of securing the airway of a fetus while maintaining umbilical circulation for newborns who are experiencing life-threatening airway obstruction. Cesarean section is completed only after ensuring the neonate’s safety. However, managing the airway of a neonate while maintaining umbilical circulation is a major challenge for anesthesiologists. Anesthesiologists must understand the physiology of both the mother and fetus, and extensive discussions with obstetricians, pediatricians, otolaryngologists, and nursing staff prior to the procedure are essential. This review provides an overview of the EXIT and details of airway management for neonates. [ABSTRACT FROM AUTHOR]

Hypoglossal nerve palsy after general anesthesia is an exceptionally rare complication, which has varied etiology. We present a case of unilateral hypoglossal nerve palsy resulting from repeated airway intervention for general anesthesia. A 57-year-old woman was scheduled to undergo modified radical mastectomy. During endotracheal intubation, the patient had Cormack's grade III—a severe airway condition. After the first intubation attempt failed, the intubation was attempted a second time using a stylet inside the endotracheal tube with cricoid pressure; this attempt was successful. In the evening of the operation day, the patient complained of dysarthria and dysphagia. Physical examination revealed deviation of the tongue to the right, which may have been caused by traumatic hypoglossal nerve injury. This case reviews the pathophysiology, prevention, and management of hypoglossal nerve palsy. [ABSTRACT FROM AUTHOR]

Sutureless aortic valve replacement was performed in a 72-year-old female patient with severe aortic stenosis who had undergone coronary revascularization and pacemaker implantation. After valve excision, decalcification was deliberately incompletely performed at the commissure of the left- and non-coronary cusp to obtain a regular and circular annular margin. After implantation of the stented valve, no paravalvular leakage was noted on water irrigation testing. Upon weaning from cardiopulmonary bypass, a moderate degree of paravalvular leakage was observed by transesophageal echocardiography at the junction of the left- and non-coronary cusp. Instead of removing the valve and performing more complete decalcification to implant a larger valve, secondary balloon dilatation and warm sterile water irrigation were performed to allow further expansion and fixing of the metal alloy stent around the aortic wall to minimize the duration of aortic cross-clamp. No paravalvular leakage was observed thereafter and the patient was discharged without any complications. [ABSTRACT FROM AUTHOR]

Background: Core body temperature (TC) can decrease during general anesthesia. Particularly in elderly patients, more aggressive strategies to prevent intraoperative hypothermia may be required. Here, we investigated the effect of a heated humidifier on intraoperative TC decrease in the elderly. Methods: Twenty-four elderly patients were randomly assigned into two groups: those who used a heated humidifier (group H) and those who used a conventional ventilator circuit with a heat moisture exchanger (group C). TC was measured continuously at the esophagus at several time-points during surgery. Results: In group C, TC significantly decreased 90 minutes after skin incision (P < 0.001), while significant differences were not noted in group H during surgery. Comparing the two groups, TC decreased more in group C than in group H at 60, 90, 120, and 150 minutes after skin incision (group C vs. group H: −0.6°C vs. −0.3°C, P = 0.025; −0.7°C vs. −0.4°C, P = 0.012; −0.9°C vs. −0.4°C, P = 0.006; and −1.0°C vs. −0.5°C, P = 0.013, respectively). There were no significant differences between the two groups for any other parameters. Conclusions: A heated humidifier is more effective in preventing intraoperative TC decrease in elderly patients than a heat moisture exchanger. However, further studies with a larger population are required to substantiate its clinical use. [ABSTRACT FROM AUTHOR]

Background: The study investigated in detail the current status of the consultations requested in a pain clinic. We evaluated the characteristics of the consultations to determine the kind of contents requested, referring departments and factors including demographics, co-morbidities, previous medical problems, and the descriptions of the reasons for the consultation to the pain clinic. Methods: Clinical data were collected in the authors' institution between 1 January 2009 and 31 December 2013. The medical records were reviewed and compared. Characteristics of both outpatients and inpatients were analysed. Results: Data from 1,140 patients was available for this study. Seven hundred thirteen individuals belonged to the outpatient group and 427 individuals belonged to the inpatient group. Orthopedic surgery, neurosurgery, and otolaryngology were the main departments that requested consultations to the pain clinic. The most frequent requested lesion and diagnostic term were low back and lumbar spinal stenosis, respectively, and the most common reason for consulting was for “control of pain not controlled by medications.” Factors that were significantly different between the two groups were gender, questions about other illnesses apart from the main diagnoses, history of specific diseases, acute onset, cancer, operation within 3 months, and physical system abnormalities. Conclusions: The medical problems addressed by a pain clinic consultation service were diverse. It is rational to develop standardized guidelines for pain consultations, and treatment strategies aimed at alleviating pain per se as well as caring for comorbid conditions. [ABSTRACT FROM AUTHOR]

Background: The authors hypothesized that the continuous infusion of ramosetron 0.15 mg following a 0.15 mg bolus administration would maintain higher 5-hydroxytryptamine type 3 receptor occupancy levels and be more effective in preventing postoperative nausea and vomiting (PONV) than a 0.3 mg single bolus administration. We conducted a study to compare the efficacy of single bolus ramosetron administration with the combination of continuous infusion following intravenous bolus administration for PONV prophylaxis. Methods: One hundred and fifty female patients undergoing thyroidectomy were allocated randomly to one of three groups to receive a placebo (Group 1, n = 49), 0.3 mg of IV ramosetron (Group 2, n = 53), or the continuous infusion of 0.15 mg ramosetron following a bolus administration of 0.15 mg of ramosetron (Group 3, n = 48). Anesthesia was maintained with sevoflurane and N2O. The incidence of PONV, nausea severity, and use of rescue antiemetics during the postoperative 24 hours were recorded. Results: Group 1 showed higher incidences of PONV during the postoperative 24 hour than Group 2 (81% vs. 58%, P = 0.02) and Group 3 (81% vs. 48%, P < 0.01), but there was no difference between Groups 2 and 3 (P = 0.39). The use of rescue antiemetics was significantly lower in Groups 2 and 3 than Group 1 during the postoperative 6 to 24 hours. Conclusions: There were no significant differences of incidence and severity of PONV between ramosetron 0.3 mg single bolus administration and the combination of ramosetron infusion after 0.15 mg bolus administration. [ABSTRACT FROM AUTHOR]