Predicting optimal endotracheal tube size and depth in pediatric patients using demographic data and machine learning techniques / 대한마취과학회지

Background@#Use of endotracheal tubes (ETTs) with appropriate size and depth can help minimize intubation-related complications in pediatric patients. Existing age-based formulae for selecting the optimal ETT size present several inaccuracies. We developed a machine learning model that predicts the optimal size and depth of ETTs in pediatric patients using demographic data, enabling clinical applications. @*Methods@#Data from 37,057 patients younger than 12 years who underwent general anesthesia with endotracheal intubation were retrospectively analyzed. Gradient boosted regression tree (GBRT) model was developed and compared with traditional age-based formulae. @*Results@#The GBRT model demonstrated the highest macro-averaged F1 scores of 0.502 (95% CI 0.486, 0.568) and 0.669 (95% CI 0.640, 0.694) for predicting the uncuffed and cuffed ETT size (internal diameter [ID]), outperforming the age-based formulae that yielded 0.163 (95% CI 0.140, 0.196, P < 0.001) and 0.392 (95% CI 0.378, 0.406, P < 0.001), respectively. In predicting the ETT depth (distance from tip to lip corner), the GBRT model showed the lowest mean absolute error (MAE) of 0.71 cm (95% CI 0.69, 0.72) and 0.72 cm (95% CI 0.70, 0.74) compared to the age-based formulae that showed an error of 1.18 cm (95% CI 1.16, 1.20, P < 0.001) and 1.34 cm (95% CI 1.31, 1.38, P < 0.001) for uncuffed and cuffed ETT, respectively. @*Conclusions@#The GBRT model using only demographic data accurately predicted the ETT size and depth. If these results are validated, the model may be practical for predicting optimal ETT size and depth for pediatric patients.

Association of the perfusion index with postoperative acute kidney injury: a retrospective study / 대한마취과학회지

Background@#Many studies have examined the risk factors for postoperative acute kidney injury (AKI), but few have focused on intraoperative peripheral perfusion index (PPI) that has recently been shown to be associated with postoperative morbidity and mortality. Therefore, this study aimed to evaluate the relationship between intraoperative PPI and postoperative AKI under the hypothesis that lower intraoperative PPI is associated with AKI occurrence. @*Methods@#We retrospectively searched electronic medical records to identify patients who underwent surgery at the general surgery department from May 2021 to November 2021. Patient baseline characteristics, pre- and post-operative laboratory test results, comorbidities, intraoperative vital signs, and discharge profiles were obtained from the Institutional Clinical Data Warehouse and VitalDB. Intraoperative PPI was the primary exposure variable, and the primary outcome was postoperative AKI. @*Results@#Overall, 2,554 patients were identified and 1,586 patients were included in our analysis. According to Kidney Disease Improving Global Outcomes (KDIGO) criteria, postoperative AKI occurred in 123 (7.8%) patients. We found that risks of postoperative AKI increased (odds ratio: 2.00, 95% CI [1.16, 3.44], P = 0.012) when PPI was less than 0.5 for more than 10% of surgery time. Other risk factors for AKI occurrence were male sex, older age, higher American Society of Anesthesiologists physical status, obesity, underlying renal disease, prolonged operation time, transfusion, and emergent operation. @*Conclusions@#Low intraoperative PPI was independently associated with postoperative AKI.

Open datasets in perioperative medicine: a narrative review

With the growing interest of researchers in machine learning and artificial intelligence (AI) based on large data, their roles in medical research have become increasingly prominent. Despite the proliferation of predictive models in perioperative medicine, external validation is lacking. Open datasets, defined as publicly available datasets for research, play a crucial role by providing high-quality data, facilitating collaboration, and allowing an objective evaluation of the developed models. Among the available datasets for surgical patients, VitalDB has been the most widely used, with the Medical Informatics Operating Room Vitals and Events Repository recently launched and the Informative Surgical Patient dataset for Innovative Research Environment expected to be released soon. For critically ill patients, the available resources include the Medical Information Mart for Intensive Care, the eICU Collaborative Research Database, the Amsterdam University Medical Centers Database, and the High time Resolution ICU Dataset, with the anticipated release of the Intensive Care Network with Million Patients’ information for the AI Clinical decision support system Technology dataset. This review presents a detailed comparison of each to enrich our understanding of these open datasets for data science and AI research in perioperative medicine.

Artificial intelligence in perioperative medicine: a narrative review / 대한마취과학회지

Recent advancements in artificial intelligence (AI) techniques have enabled the development of accurate prediction models using clinical big data. AI models for perioperative risk stratification, intraoperative event prediction, biosignal analyses, and intensive care medicine have been developed in the field of perioperative medicine. Some of these models have been validated using external datasets and randomized controlled trials. Once these models are implemented in electronic health record systems or software medical devices, they could help anesthesiologists improve clinical outcomes by accurately predicting complications and suggesting optimal treatment strategies in real-time. This review provides an overview of the AI techniques used in perioperative medicine and a summary of the studies that have been published using these techniques. Understanding these techniques will aid in their appropriate application in clinical practice.

Effect of postoperative non-steroidal anti-inflammatory drugs on anastomotic leakage after pancreaticoduodenectomy / 대한마취과학회지

Background@#Although the association between an increase in anastomotic leakage (AL) and non-steroidal anti-inflammatory drugs (NSAIDs) has been reported in gastrointestinal surgeries, this issue has rarely been addressed for pancreaticoduodenectomy (PD). We aimed to investigate the association between postoperative NSAIDs administration and clinically relevant AL (CR-AL) following PD. @*Methods@#We retrospectively evaluated 2,163 consecutive patients who underwent PD between 2007 and 2019. The patients were divided into two groups; patients who received and did not receive NSAIDs by postoperative day (POD) 5. We conducted a propensity score analysis using inverse probability of treatment weighting (IPTW) to adjust the baseline differences between both groups. We compared the occurrence of CR-AL and other postoperative outcomes before and after IPTW. Further, we used the multivariable binary logistic regression method for a sensitivity analysis for CR-AL. @*Results@#A total of 2,136 patients were included in the analysis. Of these, 222 (10.4%) received NSAIDs by POD 5. The overall occurrence rate of CR-AL was 14.9%. After IPTW, postoperative NSAIDs were significantly associated with CR-AL (odds ratio [OR]: 1.24, 95% CI [1.05, 1.47], P = 0.012), prolonged postoperative hospitalization (OR: 1.31, 95% CI [1.14, 1.50], P < 0.001), and unplanned readmission within 30 days postoperatively (OR 1.48: 95% CI [1.15, 1.91], P = 0.002). However, this association was not consistent in the sensitivity analysis. @*Conclusions@#Postoperative NSAIDs use was significantly associated with an increase in CR-AL incidence following PD. However, sensitivity analysis failed to show its association, which precludes a firm conclusion of its detrimental effect.

System of integrating biosignals during hemodialysis: the CONTINUAL (Continuous mOnitoriNg viTal sIgNdUring hemodiALysis) registry

Appropriate monitoring of intradialytic biosignals is essential to minimize adverse outcomes because intradialytic hypotension and arrhythmia are associated with cardiovascular risk in hemodialysis patients. However, a continuous monitoring system for intradialytic biosignals has not yet been developed. Methods: This study investigated a cloud system that hosted a prospective, open-source registry to monitor and collect intradialytic biosignals, which was named the CONTINUAL (Continuous mOnitoriNg viTal sIgN dUring hemodiALysis) registry. This registry was based on real-time multimodal data acquisition, such as blood pressure, heart rate, electrocardiogram, and photoplethysmogram results. Results: We analyzed session information from this system for the initial 8 months, including data for some cases with hemodynamic complications such as intradialytic hypotension and arrhythmia. Conclusion: This biosignal registry provides valuable data that can be applied to conduct epidemiological surveys on hemodynamic complications during hemodialysis and develop artificial intelligence models that predict biosignal changes which can improve patient outcomes.

Comparison of Harmonic scalpel and monopolar cautery for capsulectomy at the second stage of expander/implant breast reconstruction

Background@#Capsular contracture is a common complication of two-stage expander/implant breast reconstruction. To minimize the risk of this complication, capsulectomy is performed using monopolar cautery or ultrasonic surgical instrumentation, the latter of which can be conducted with a Harmonic scalpel. To date, there is disagreement regarding which of the two methods is superior. The purpose of this study was to compare postoperative outcomes between a group of patients who underwent surgery using a Harmonic scalpel and another group treated with monopolar cautery. @*Methods@#A retrospective chart review was conducted of patients who underwent capsulectomy as part of two-stage breast reconstruction between January 2018 and February 2019 and who received at least 1 month of follow-up after surgery. Operative time and postoperative outcomes, including drainage duration, were analyzed. @*Results@#In total, 36 female patients underwent capsulectomy. The monopolar group consisted of 18 patients and 22 breasts, while the Harmonic scalpel group consisted of 18 patients and 21 breasts. There was no statistically significant difference in demographics between the two groups. The Harmonic scalpel group had a significantly shorter mean drainage duration (6.65 days vs. 7.36 days) and a smaller mean total drainage volume (334.69 mL vs. 433.54 mL) than the monopolar cautery group (P<0.05). No statistically significant difference was observed with regard to seroma or hematoma formation. @*Conclusions@#The Harmonic scalpel approach for capsulectomy reduced the total drainage volume and drainage duration compared to the monopolar cautery approach. Therefore, this approach could serve as a good alternative to electrocautery.

Safety of blood mixture transfusion by rapid infusion device in liver transplantation recipients

BACKGROUND: Information on biochemical changes following rapid transfusion of blood mixtures in liver transplantation patients is limited. METHODS: A blood mixture composed of red blood cells, fresh frozen plasma, and 0.9% saline was prepared in a ratio of 1 unit:1 unit:250 ml. During massive hemorrhage, 300 ml of the blood mixture was repeatedly transfused. A blood mixture sample as well as pre- and post-transfusion arterial blood samples were collected at the first, third, fifth, and seventh bolus transfusions. Changes in pH, hematocrit, electrolytes, and glucose were measured with a point-of-care analyzer. The biochemical changes were described, and the factors driving the changes were sought through linear mixed effects analysis. RESULTS: A total of 120 blood samples from 10 recipients were examined. Potassium and sodium levels became normalized during preservation. Biochemical changes in the blood mixture were significantly related to the duration of blood bank storage and reservoir preservation (average R2 = 0.41). Acute acidosis and hypocalcemia requiring immediate correction occurred with each transfusion. Both the pre-transfusion value of the patient and the blood mixture value were significant predictors of post-transfusion changes in the body (average R2 = 0.87); however, the former was more crucial. CONCLUSIONS: Rapid infusion of blood mixture is relatively safe because favorable biochemical changes occur during storage in the reservoir, and the composition of the blood mixture has little effect on the body during rapid transfusion in liver recipients. However, acute hypocalcemia and acidosis requiring immediate correction occurred frequently due to limited citrate metabolism in the liver recipients.

Safety and efficacy of transcutaneous bone conduction implant surgery for hearing improvement in microtia patients with bilateral hearing impairment

BACKGROUND@#In microtia patients with bilateral hearing impairment, hearing improvement is crucial for language development and performance. External auditory canal reconstruction (EACR) has been performed to improve hearing, but often results in complications. We performed transcutaneous bone conduction implant (TBCI) surgery in these patients. This study aimed to evaluate the safety and efficacy of TBCI surgery.@*METHODS@#A retrospective review was performed of five patients who underwent auricular reconstruction and TBCI surgery and 12 patients who underwent EACR between March 2007 and August 2018. Hearing improvement was measured based on the air-bone gap values using pure-tone audiometry over a 6-week postoperative period. We reviewed other studies on hearing improvement using EACR and compared the findings with our results. The surgical techniques for TBCI were reviewed through case analyses.@*RESULTS@#Postoperative hearing outcomes showed a significant improvement, with a mean gain of 34.1 dB in the TBCI cohort and 14.1 dB in the EACR cohort. Both gains were statistically significant; however, the TBCI cohort showed much larger gains. Only three of the 12 patients who underwent EACR achieved hearing gains of more than 20 dB, which is consistent with previous studies. All patients who underwent TBCI surgery demonstrated hearing gains of more than 20 dB and experienced no device-related complications.@*CONCLUSIONS@#TBCI is a safe and effective method of promoting hearing gains in microtia patients with bilateral hearing impairment. TBCI surgery provided better hearing outcomes than EACR and could be performed along with various auricular reconstruction techniques using virgin mastoid skin.

Unilateral pedicled transverse rectus abdominis musculocutaneous flap and unilateral free deep inferior epigastric artery perforator flap as a surgical alternative in bilateral autologous breast reconstruction

BACKGROUND: Bilateral microsurgical autologous reconstruction is known to increase operating time, costs, and complications compared to unilateral procedures. This study aimed to determine whether a unilateral pedicled transverse rectus abdominis myocutaneous (TRAM) flap and a unilateral deep inferior epigastric artery perforator (DIEP) free flap could be a feasible option for bilateral reconstruction in selected circumstances. METHODS: A retrospective chart review identified patients who underwent unilateral pedicled TRAM and unilateral DIEP reconstruction for bilateral breast reconstruction between 2011 and 2014. Surgical outcomes, complications, and aesthetic scale questionnaire responses were evaluated. RESULTS: Fourteen patients were included in this study. Ten patients received bilateral immediate reconstruction, while four patients with a previous history of mastectomy underwent unilateral immediate reconstruction and contralateral delayed reconstruction. All flaps survived without any major complications. A case of nipple-areolar skin necrosis on the pedicled TRAM side and a case of mild abdominal bulging at the free DIEP donor site were reported. There was no partial flap necrosis or palpable fat necrosis. On the aesthetic outcome scale, the free DIEP flaps scored significantly higher than did the pedicled TRAM flaps for overall shape, the upper medial and lower lateral quadrant, and the lateral chest wall. CONCLUSIONS: Our findings suggest that a unilateral pedicled TRAM flap together with a unilateral free DIEP flap could be performed as a bridging surgical option as institutions move toward bilateral free-flap reconstructions, as a way to reduce operating time and the risk of microsurgery-related complications with acceptable donor site morbidity and aesthetic outcomes.

Impact of hormonal therapy and other adjuvant therapies on contralateral breast volume change after implant-based breast reconstruction

BACKGROUND: Adjuvant therapy after breast surgery, including tamoxifen or aromatase inhibitors, improves the postoperative outcomes and long-term survival of breast cancer patients. The aim of this study was to determine whether volume changes occurred in the contralateral breast during hormonal or other adjuvant therapies. METHODS: This study reviewed 90 patients who underwent unilateral breast reconstruction between September 2012 and April 2018 using tissue expanders and a permanent implant after the surgical removal of breast cancer. The volume of the contralateral breast was measured using a cast before the first (tissue expander insertion) and second (permanent implant change) stages of surgery. Changes in breast volume were evaluated to determine whether adjuvant therapy such as hormonal therapy, chemotherapy, and radiation therapy influenced the volume of the contralateral breast. RESULTS: The group receiving tamoxifen therapy demonstrated a significant decrease in volume compared with the group without tamoxifen (−7.8% vs. 1.0%; P=0.028). The aromatase inhibitor–treated group showed a significant increase in volume compared with those who did not receive therapy (−6.2% vs. 4.5%; P=0.023). There were no significant differences between groups treated with other hormonal therapy, chemotherapy, or radiation therapy. CONCLUSIONS: Patients who received tamoxifen therapy showed a significant decrease in volume in the contralateral breast, while no significant change in weight or body mass index was found. Our findings suggest that we should choose smaller implants for premenopausal patients, who have a high likelihood of receiving tamoxifen therapy.

Correction to: Hard- and soft-tissue profiles of the midface region in patients with skeletal Class III malocclusion using cone-beam computed tomography multiplanar-reconstructed image analysis / 대한치과교정학회지

In the article, the ‘Class’ of skeletal malocclusion was misprinted as ‘class’ in the main text. The publisher would like to apologize for any inconvenience caused.

Anesthesia research in the artificial intelligence era

A noteworthy change in recent medical research is the rapid increase of research using big data obtained from electrical medical records (EMR), order communication systems (OCS), and picture archiving and communication systems (PACS). It is often difficult to apply traditional statistical techniques to research using big data because of the vastness of the data and complexity of the relationships. Therefore, the application of artificial intelligence (AI) techniques which can handle such problems is becoming popular. Classical machine learning techniques, such as k-means clustering, support vector machine, and decision tree are still efficient and useful for some research problems. The deep learning techniques, such as multi-layer perceptron, convolutional neural network, and recurrent neural network have been spotlighted by the success of deep belief networks and convolutional neural networks in solving various problems that are difficult to solve by conventional methods. The results of recent research using artificial intelligence techniques are comparable to human experts. This article introduces technologies that help researchers conduct medical research and understand previous literature in the era of AI.

Hard- and soft-tissue profiles of the midface region in patients with skeletal Class III malocclusion using cone-beam computed tomography multiplanar-reconstructed image analysis / 대한치과교정학회지

OBJECTIVE: This study examined cone-beam computed tomography (CBCT)-derived multiplanar-reconstructed (MPR) cross-sections to clarify the salient characteristics of patients with skeletal class III malocclusion with midface deficiency (MD). METHODS: The horizontal and sagittal plane intersection points were identified for middle-third facial analysis in 40 patients in the MD or normal (N) groups. MPR images acquired parallel to each horizontal plane were used for length and angular measurements. RESULTS: A comparison of the MD and N groups revealed significant differences in the zygoma prominence among female patients. The convex zygomatic area in the N group was larger than that in the MD group, and the inferior part of the midface in the N group was smaller than that in the MD group for both male and female patients. A significant difference was observed in the concave middle maxillary area among male patients. CONCLUSIONS: This study was conducted to demonstrate the difference between MD and normal face through MPR images derived from CBCT. Male patients in the MD group had a more flattened face than did those in the N group. Female patients in the MD group showed a concave-shaped lower section of the zygoma, which tended to have more severe MD. These findings indicate that orthognathic surgery to improve skeletal discrepancy requires different approaches in male and female patients.

A pillow of 8 cm height did not improve laryngeal view and alignment of airway axes but increased anesthesiologist discomfort compared to a pillow of 4 cm height during tracheal intubation in adult patients / 대한마취과학회지

BACKGROUND: Neck flexion by head elevation using an 8 to 10 cm thick pillow and head extension has been suggested to align the laryngeal, pharyngeal and oral axis and facilitate tracheal intubation. Presently, the laryngeal view and discomfort for tracheal intubation were evaluated according to two different degrees of head elevation in adult patients. METHODS: This prospective randomized, controlled study included 50 adult patients aged 18 to 90 years. After induction of anesthesia, the Cormack Lehane grade was evaluated in 25 patients using a direct laryngoscope while the patient's head was elevated with a 4 cm pillow (4 cm group) and then an 8 cm pillow (8 cm group). In the other 25 patients, the grades were evaluated in the opposite sequence and tracheal intubation was performed. The success rate and anesthesiologist's discomfort score for tracheal intubation, and laryngeal, pharyngeal and oral axes were assessed. RESULTS: There were no differences in the laryngeal view and success rate for tracheal intubation between the two groups. The discomfort score during tracheal intubation was higher in the 8 cm group when the patient's head was elevated 4 cm first and then 8 cm. The alignment of laryngeal, pharyngeal and oral axes were not different between the two degrees of head elevation. CONCLUSIONS: A pillow of 8 cm height did not improve laryngeal view and alignment of airway axes but increased the anesthesiologist discomfort, compared to a pillow of 4 cm height, during tracheal intubation in adult patients.

Anesthetic management of laparoscopic pheochromocytoma excision in a patient with a Fontan circulation: a case report / 대한마취과학회지

An 18-year-old male with a Fontan circulation underwent excision of a pheochromocytoma after conversion from laparoscopic surgery. The pneumoperitoneum established for laparoscopic surgery may have adverse effects on the Fontan circulation, because it increases the intra-abdominal pressure (IAP), intra-thoracic pressure, pulmonary vascular resistance, and systemic vascular resistance (SVR), and decreases cardiac preload and cardiac output. Meticulous monitoring is also required during carbon dioxide exsufflation, because a rapid decrease in IAP can provoke hemodynamic deterioration by decreasing venous return and SVR. Furthermore, catecholamines released by the pheochromocytoma can worsen the hemodynamic status of Fontan circulation during surgery. Therefore, sophisticated intraoperative anesthetic care is required during laparoscopic pheochromocytoma excision in patients with a Fontan circulation.

Antiallodynic effects of vitamin C and vitamin E in chronic post-ischemia pain rat model / 대한마취과학회지

BACKGROUND: Recent research has shown that reactive oxygen species (ROS) play a significant role in the development and persistence of neuropathic pain through central sensitization via N-methyl-D-aspartate (NMDA) receptor activation. In the present study, we examined whether the intraperitoneal administration of vitamins C and E alone or together could alleviate mechanical allodynia in a chronic post-ischemia pain (CPIP) rat model. METHODS: Vitamins C and E were administered intraperitoneally to 48 male Sprague Dawley rats once per day for 3 days before hindpaw ischemia-reperfusion (I/R) injury was induced. On the third day, the CPIP rat model was produced by inducing ischemia in the left hindpaw by applying an O-ring for 3 h, followed by reperfusion. Three days after reperfusion, hindpaw mechanical allodynia was assessed by measuring the withdrawal response to von Frey filament stimulation. The rats were sacrificed immediately after behavioral testing to determine the phosphorylated NMDA receptor subunit 1 (pNR1) and extracellular-signal-regulated kinases (pERK) levels in the spinal cord. RESULTS: When the antioxidant vitamins C and E were administered intraperitoneally to CPIP rats, I/R injury-induced mechanical allodynia was attenuated, and pNR1 and pERK levels were decreased in the rat spinal cord. Additionally, the co-administration of both vitamins had an increased antiallodynic effect. CONCLUSIONS: The reduced phosphorylated NR1 and ERK levels indicate that vitamins C and E inhibit the modulation of spinal cord neuropathic pain processing. Co-administration of vitamins C and E had a greater antiallodynic effect.

Rocuronium-induced withdrawal movement: influence of ketorolac or a combination of lidocaine and ketorolac pretreatment / 대한마취과학회지

BACKGROUND: Pain on injection of rocuronium is a common clinical problem. We compared the efficacy of lidocaine, ketorolac, and the 2 in combination as pretreatment for the prevention of rocuronium-induced withdrawal movement. METHODS: For this prospective, randomized, placebo-controlled, double-blind study a total of 140 patients were randomly allocated to one of 4 treatment groups to receive intravenously placebo (saline), lidocaine (20 mg), ketorolac (10 mg), or both (n = 35 for each group), with venous occlusion. The tourniquet was released after 2 min and anesthesia was performed using 5 mg/kg thiopental sodium followed by 0.6 mg/kg rocuronium. The withdrawal response was graded on a 4-point scale in a double-blind manner. RESULTS: The overall incidence of withdrawal movements after rocuronium was 34.3% with lidocaine (P = 0.001), 40% with ketorolac (P = 0.004), and 8.6% with both (P < 0.001), compared with 74.3% with placebo. There was a significantly lower incidence of withdrawal movements in patients receiving the lidocaine/ketorolac combination than in those receiving lidocaine or ketorolac alone (P = 0.009 and 0.002, respectively). The incidence of moderate to severe withdrawal movements was 14.3% with lidocaine, 17.2% with ketorolac, and 2.9% with lidocaine/ketorolac combination, as compared to 45.7% with the placebo. There was no significant difference in withdrawal movement between the lidocaine group and the ketorolac group. CONCLUSIONS: Ketorolac pretreatment had an effect comparable to that of lidocaine in attenuating rocuronium-induced withdrawal movements and the lidocaine/ketorolac combination pretreatment, compared with lidocaine or ketorolac alone, effectively reduced withdrawal movements during rocuronium injection.

Comparison of the renal safety between carbon dioxide absorbent products under sevoflurane anesthesia: a pilot study / 대한마취과학회지

BACKGROUND: The chemical reaction of carbon dioxide absorbent and sevoflurane is known to produce compound A. However, carbon dioxide absorbents are not controlled by the Food and Drug Administration, but are treated as industrial products in some nations. Moreover, carbon dioxide absorbents differ in their capacities to produce compound A, because their chemical compositions differ. In this study, we compared the renal safety between carbon dioxide absorbent products in patients under sevoflurane anesthesia. METHODS: Eighty patients with no preexisting renal disease undergoing elective gynecologic surgery were randomly assigned to receive sevoflurane or isoflurane anesthesia with one of four carbon dioxide absorbent products (Sodasorblime(R), Sodalyme(R), Sodasorb(R), Spherasorb(R)) at the same fresh gas flow of 2 L/min. The renal safety was evaluated by changes of blood urea nitrogen (BUN), creatinine and urine N-acetyl-b-glucoseaminidase (NAG)-creatinine ratio at 24 hours and 72 hours after surgery from preoperative level. RESULTS: There was no significant difference in the renal safety indicators between carbon dioxide absorbents during sevoflurane anesthesia (P > 0.05). However, the BUN and urine NAG-creatinine ratios at 72 hours after surgery were higher in isoflurane anesthesia in some carbon dioxide absorbent groups (P = 0.03 and 0.04, respectively). CONCLUSIONS: We could not find significant differences of renal safety indicators with carbon dioxide absorbents. Although the adverse effect of carbon dioxide absorbents on renal function was not proved, consideration should be given to their contol by the regulation on their efficacy and safety because carbon dioxide absorbents can produce compound A.

Total Tongue Reconstruction with Folded Anterolateral Thigh Free Flap

Tongue reconstruction after oncologic resection with free flap is important to conserve function and shape. Vertical rectus myocutaneous free flap is usually used for total tongue reconstruction, but our patient was thin and primary closure after flap elevation seemed hard. So we used anterolateral thigh free flap to reduce donor site morbidity and to maintain bulk of the tongue as much as possible. Deepithelization of both middle side of flap and folding was done to mimic normal tongue base's shape and volume. Flap survived without complication and patient underwent concurrent chemoradiation therapy three weeks after surgery. Anterolateral thigh free flap can be good candidate for total tongue reconstruction especially in thin patient.