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.

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.

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.

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.

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.

Hemodynamic effect of full flexion of the hips and knees in the supine position: a comparison with straight leg raising / 대한마취과학회지

BACKGROUND: Straight raising of the legs in the supine position or Trendelenburg positioning has been used to treat hypotension or shock, but the advantages of these positions are not clear and under debate. We performed a crossover study to evaluate the circulatory effect of full flexion of the hips and knees in the supine position (exaggerated lithotomy), and compare it with straight leg raising. METHODS: This study was a prospective randomized crossover study from the tertiary care unit at our university hospital. Twenty-two patients scheduled for off-pump coronary artery bypass surgery were enrolled. Induction and maintenance of anesthesia were standardized. Exaggerated lithotomy position or straight leg raising were randomly selected in the supine position. Hemodynamic variables were measured in the following sequence: 10 min after induction, 1, 5, and 10 min following the designated position, and 1 and 5 min after returning to the supine position. Ten min later, the other position was applied to measure the same hemodynamic variables. RESULTS: During the exaggerated lithotomy position, cerebral and coronary perfusion pressure increased significantly (P < 0.01) without a change in cardiac output. During straight leg raising, cardiac output increased at 5 min (P < 0.05) and cerebral and coronary perfusion pressures did not increase except for cerebral perfusion pressure at 1 min. However, the difference between the two groups at each time point in terms of cerebral perfusion pressure was clinically insignificant. CONCLUSIONS: Full flexion of the hips and knees in the supine position did not increase cardiac output but may be more beneficial than straight leg raising in terms of coronary perfusion pressure.

The influence of DNA polymorphism of multidrug resistant 1 (MDR1) on the effect of midazolam pretreatment in children / 대한마취과학회지

BACKGROUND: Patients showed a different response following intravenous midazolam injection. Some children showed irritability or were not sedated by midazolam. We hypothesized that there may be genetic variations of the MDR1 gene, based on the response to midazolam. METHODS: One hundred and ninety-three pediatric patients were recruited in this study. Midazolam (0.1 mg/kg) was injected intravenously before surgery. Anxiety score (activity, vocalizations, emotional expressivity, state of apparent arousal) was checked before and 5 minutes after midazolam injection. In addition, other manifestations after midazolam injection were recorded. After anesthesia, 2 ml of blood was sampled. Children were genotyped MDR1. Haplotype was analyzed using the software package PHASE, version 2.0. RESULTS: The observed frequencies of MDR1 haplotype of TTT, TGC, CAC, CGC were 0.334, 0.205, 0.182 and 0.225, respectively. There was no significant correlation between the response of midazolam and the MDR1 haplotype of TTT, TGC, CAC or CGC (P = 0.98). CONCLUSIONS: Genotyping of MDR1 may not be related to the response of midazolam in children.

The target concentration of remifentanil to suppress the hemodynamic response to endotracheal intubation during inhalational induction with desflurane / 대한마취과학회지

BACKGROUND: Anesthesia induction with desflurane is troublesome because of the frequent sympathetic hyperactivity during desflurane administration. We thought that a low concentration of desflurane combined with a target-controlled infusion (TCI) of remifentanil would eliminate the desflurane-related complications and provide hemodynamic stability during desflurane induction. An up-and-down study was planned to find the target effect-site concentration of remifentanil to block the hemodynamic response to endotracheal intubation, the highest level of stimulus, during anesthesia induction with administering desflurane at 1 MAC. METHODS: Remifentanil TCI was initiated before desflurane administration. When the preset target was achieved, spontaneous inhalation of desflurane 1 MAC was performed until the patients became unconscious. Laryngoscopic tracheal intubation was facilitated with rocuronium injection. The starting concentration of remifentanil and the test space were 5 and 1 ng/ml, respectively. The criteria for up-and-down was a 20% increase of the mean arterial pressure or heart rate after intubation. The median effective concentration (EC50) of remifentanil was calculated from 6 independent pairs. The complications related with remifentanil and desflurane were assessed during the study. RESULTS: We studied 20 patients using 2-5 ng/ml of the effect-site concentrations of remifentanil. The EC50 of remifentanil was 3.7 ng/ml. Loss of consciousness was achieved at 125 +/- 22 s after desflurane inhalation and this was irrespective of the combined remifentanil concentrations. Any remifentanil-related complication was not observed. Transient cough was seen in one patient who received 2 ng/ml of remifentanil. CONCLUSIONS: We demonstrated that uncomplicated induction with desflurane was possible by the use of target-controlled remifentanil. The EC50 of remifentanil to block the hemodynamic response to tracheal intubation was 3.7 ng/ml during inhalational induction with 1 MAC desflurane.

Occurrence of complete atrioventricular block during surgery / 대한마취과학회지

No abstract available.

Anesthesia for synchronous liver and kidney transplantation in a child: A case report / 대한마취과학회지

Synchronous liver and kidney transplantation (SLK) is considered a treatment of choice for an end-stage liver disease patient with irreversible kidney disease. Several perioperative renal supportive treatments, especially continuous renal replacement therapy (CRRT), have contributed to the effective control of hypervolemia and electrolytes and acid-base disturbances leading to high success rate in adults. However, anesthesia for SLK in children is frequently difficult since the CRRT is seldom available because of difficulty in securing large venous lines. In addition, conventional techniques such as venovenous bypass and side-clamping of the inferior vena cava are less applicable in small children causing difficult volume control. Herein, we report a case of SLK in a child with glycogen storage disease type I with a review of literature.

Hypercapnic coma at the postanesthesia care unit: A case report / 대한마취과학회지

A 59-year-old woman underwent explorative laparotomy under general anesthesia for mechanical ileus. The patient had rectal cancer with multiple metastasis, and was receiving 1.5-2 mg of intravenous morphine per hour due to severe abdominal pain. After about 3 hours of general anesthesia, the patient was extubated and transferred to postanesthesia care unit. The patient was supplied with 6 L/min of oxygen by facial mask. In 30 minutes, the patient showed no response to verbal order and pain stimulus with sluggish eye reflex, although pulse-oximeter showed 98-99%. After emergent intubation, arterial blood gas was sampled, and the result showed severe acidosis with hypercapnia. The patient was transferred to intensive care unit, and after 1 hour of mechanical ventilation the patient became conscious then fully recovered without further complication.

The pain caused by a 2% propofol target-controlled infusion during anesthesia induction in adults / 대한마취과학회지

BACKGROUND: An increasing number of cases of target-controlled infusion (TCI) of propofol have substituted 2% propofol for 1% due to the concerns about lipid deposition and the practical convenience. However, 2% propofol may possess a higher proportion of free aqueous propofol because of the relatively decreased lipid-solvent ratio as compared to that for 1% propofol. We performed a prospective, randomized, double-blind trial to evaluate the pain of 1% and 2% propofol TCI. The efficacy of lidocaine pretreatment to abolish the pain was also tested for each concentration of propofol. METHODS: Two hundred adult patients were randomly allocated to 4 groups according to the pretreatment drugs and propofol concentrations; placebo (normal saline) and 1% propofol group (group 1), placebo and 2% propofol group (group 2), lidocaine and 1% propofol group (group 1L), and lidocaine and 2% propofol group (group 2L). Administration of pretreatment drug was followed by TCI with using each concentration of propofol. Pain was assessed using a four-point scale during propofol infusion. RESULTS: Propofol pain was more frequent (82% vs. 63%, respectively, P = 0.026), and severe (P = 0.002) for the group 2 than for group 1. Pain was significantly reduced by lidocaine pretreatment in the group 2L (48%) and group 1L (19%), as compared with group 2 (82%) and group 1 (63%), respectively (P < 0.001, both). However, group 2L still showed considerable pain that was similar to the pain of group 1. CONCLUSIONS: TCI of 2% propofol caused more frequent and severe pain despite of lidocaine pretreatment.

The Hemodynamic Effects of Insulin Following Overdosage with Levobupivacaine or Racemic Bupivacaine in Dogs

Although levobupivacaine (LBUP) is less cardiotoxic than racemic bupivacaine (RBUP), the resuscitation from the LBUP-induced cardiovascular collapse (CVC) has not been easy as expected. Following the recent reports that proposed the resuscitative action of insulin for the RBUP-induced CVC, a controlled trial was performed to assess the feasibility of insulin for the LBUP-induced CVC. Fourteen dogs were randomly allocated into two groups: the RBUP and LBUP groups. Each group received continuous intravenous infusions of RBUP or LBUP until the mean arterial pressure (MAP) reached 40 mmHg. Then, an intravenous bolus of insulin (2 U/kg) was administered. Both groups were successfully resuscitated. At CVC, a decrease of cardiac output and an increase of systemic vascular resistance were observed but to a lesser degree in the LBUP group (p<0.05). After insulin injection, the MAP further declined to under 40 mmHg for several minutes, which was more protracted in the LBUP group (p<0.05). The CVCs induced by LBUP or RBUP in anesthetized dogs could be successfully resuscitated by insulin. Compared with RBUP, however, the less degree of vasoconstriction by LBUP and the innate vasodilatory property of insulin yielded a delayed increment of MAP during the immediate resuscitation period in the LBUP-induced CVC.

Vancomycin-resistant Enterococcus and Methicillin-resistant Staphylococcus aureus Colonization in Liver Transplant Recipients : A Matched Control Study / 대한구급학회지

BACKGROUND: Despite improvements in surgical technique and immunosuppression, infection following liver transplantation (LT) remains a significant problem. Vancomycin-resistant Enterococcuscus (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) have become important nosocomial pathogens. This study was undertaken in attempt to evaluate clinical impact of VRE and MRSA in LT recipients. METHODS: LT recipients with VRE or MRSA colonization from 2001 to 2004 were identified and matched (age, gender, United Network for Organ Sharing status, liver disease, and transplant date) to control groups without MRSA or VRE colonization. Demographics, clinical factors, length of stay, duration of the use of the mechanical ventilator, complications and survival rates were compared with matched controls. RESULTS: Eleven patients were colonized by VRE (4.7%) and thirty patients by MRSA (13%). The common sites of VRE culture included the tip of the urinary catheter and urine. The VRE colonized group experienced more biliary complications, relaparotomies, longer length of stay at ICU and ward, and longer use of the mechanical ventilator. One year survival rate was lower in the VRE group. MRSA was commonly cultured from sputum, tip of the central venous catheter or intraarterial catheter, and blood. The MRSA group experienced more relaparotomies, pneumonia, longer stay at ICU and ward, and longer use of mechanical ventilator compared to the control. One year survival rate was lower in the MRSA group. Rejection was not associated with VRE or MRSA infection. CONCLUSIONS: VRE or MRSA colonization is associated with higher incidence of posttransplant complications and lower survival rate than LT recipients without VRE or MRSA colonization. The patients with VRE or MRSA colonization also utilized more hospital resources.

Anesthetic Management for Abdominal Aortic Aneurysm Surgey without Homologous Blood Transfusion in Adult Jehovah'sWitness : A case report

Jehovah's Witnesses present a challenge for the anesthesia professionals on account of their refusal to accept blood and blood products. Therefore, anesthesiologists must be able to individualize their treatment depending on the patients' condition. We report a case of a stent removal and aorto-biiliac bypass surgery in a Jehovah's Witness. A 69 year-old, hypertensive man presented with claudication of both lower extremities due to the distal migration of an endoaneurysmal stent. According to his previous medical history, he had a lacunar infarction in the right middle cerebral artery territory, ischemic coronary artery disease with a stent in situ, and a stent inserted for an abdominal aortic aneurysm by radiological intervention. Because he strongly refused a transfusion, human recombinant erythropoietin was used before surgery. After the erythropoietin treatment, hemoglobin level increased to 14.8 g/dl (hematocrit 47.6%). During the operation, closed-circuit cell saver was used and transfused autologous blood was saved by acute normovolemic hemodilution. The patient recovered uneventfully from the anesthesia and was transferred to the intensive care unit. He was discharged on the ninth postoperative day without complications with a hematocrit level of 28.9%.

Anesthetic Management in a Patient with Cross-Sensitivity to Muscle Relaxants: A case report / 대한마취과학회지

Anaphylactic reactions to muscle relaxants have been increasingly reported during recent 30 years. An adequate investigation of patient's history and avoidance of the muscle relaxant responsible for the previous reaction would reduce the risk of second reaction. A 56-year-old woman was admitted for laparoscopic cholecystectomy. She had a history of serious anaphylactic reaction to vecuronium. Preoperative intradermal skin test against muscle relaxants showed positive reactions to succinylcholine, atracurium and rocuronium. General anesthesia was induced with midazolam, fentanyl, 8 vol% sevoflurane mixed with 50% oxygen. Laryngeal mask airway was inserted without muscle relaxant and anesthesia was maintained with 4-6 vol% sevoflurane, air and oxygen without muscle relaxant. The anesthesia and postoperative course of this patient were uneventful.

Anatomical Basis for Supraclavicular Central Venous Catheterization Assessed by Three-Dimensional Computed Tomography / 대한마취과학회지

BACKGROUND: The current study aimed at elucidating the anatomical basis for a supraclavicular approach for central venous catheterization using three-dimensional computed tomography (3D-CT). METHODS: Retrospective review of CT images from 60 adult patients with normal body build was performed using 3D-CT reconstruction. Right-sided approach was assumed, and the skin entry point was decided as a point above the subclavian vein at the supraclavicular fossa. Measured parameters were; angles of the clavicle (Aclv) and the subclavian vein (Ascv) to the coronal plane, the distance from the clavisternomastoid angle to the skin entry point (Dse), the optimal angle of needle insertion (Ains) targeting the confluence between the internal jugular vein and the subclavian vein, the distance from the skin entry point to the confluence (Dconf), and the diameter of the confluence (Dia). Descriptive statistics were performed for the measured values. Correlation test was performed between Ascv and Aclv. RESULTS: Measured values were; Aclv = 8.0 degrees, Ascv = 5.7 degrees, Dse = 12.5 mm, Ains = 40 degrees, Dconf = 20.5 mm, and Dia = 18.1 mm. Ascv demonstrated positive correlation with corresponding Aclv (r = 0.494, P < 0.001). CONCLUSIONS: Optimal guideline for the supraclavicular approach can be provided via 3D-CT investigation. Forty degrees of needle direction to the sagittal plane and parallel to the posterior surface of the clavicle, at 1.3 cm posterior to the clavisternomastoid angle insures proper puncture of the confluence without anticipated complications.

Optimal Dose of Remifentanil to Suppress Cardiovascular Responses to Laryngoscopic Endotracheal Intubation / 대한마취과학회지

BACKGROUND: Laryngoscopic tracheal intubation causes acute hemodynamic changes such as hypertension and tachycardia. Adjuvant opioids during induction have been used to attenuate such responses. The aim of this study was to determine the optimal dose of bolus remifentanil, a newly developed ultra short acting opioid, to suppress cardiovascular responses immediately after laryngoscopic endotracheal intubation in patients anesthetized with N2O-O2-sevoflurane. METHODS: Sixty ASA I or II patients who requiring endotracheal intubation were randomly allocated to one of the four groups; C, R0.5, R1, and R2. Each group received normal saline, 0.5, 1, or 2microgram/kg of remifentanil respectively. Predetermined drugs for each group were administered over 30 seconds after induction of anesthesia with thiopental, rocuronium and 2 vol% of sevoflurane with 50% nitrous oxide. Laryngoscopic endotracheal intubation was carried out 60 seconds after the study drug administration. Mean arterial pressure (MAP) and heart rate (HR) were recorded at pre-anesthesia (PA), pre-intubation (PI) and during 5 minutes after intubation (IT-1 to IT-5). Statistical analysis was done for comparison of time and dose dependent changes among the groups. RESULTS: Baseline values were similar among the groups. IT-1 values did not change compared to PI values in R1 and R2. However, MAP and HR in R2 were significantly lower than PA values during post-intubation period. CONCLUSIONS: Bolus injection of 1microgram/kg of remifentanil blocks MAP and HR elevation after laryngoscopic endotracheal intubation without adverse effects in patients under N2O-O2-sevoflurane anesthesia.

Radiation Exposure from a Patient Treated with I-131 during Emergency Operation: A case report / 대한마취과학회지

Among the hazards in anesthesiologic field, the radiation exposure is not uncommon and is mainly from the exposure to imaging equipment. The presented case is a very extraordinary one of radiation exposure from the patient taking radioactive iodine (I-131). Recently we experienced a radiation exposure during the emergency surgery of a thyroid cancer patient who was administered I-131 before surgery. The oral administration of I-131 is recognized as a standard medical treatment for thyroid carcinoma. But the patient treated with I-131 can be a potential radiation source of external exposure to surroundings and the radiation was actually near the recommended limit of yearly exposure in spite of short surgery time. Hereby we report the case and contemplate the peri-operative risk of radiation exposure.

Use of Emergency Venoarterial Bypass for the Treatment of Acute Pulmonary Edema during Liver Transplantation: A case report / 대한마취과학회지

Liver transplantation surgery always has a risk of massive bleeding because of underlying coagulopathy and multiple collateral vessels in end-stage liver disease patients. Moreover it adds the risk that operation itself has been done around large arteries and veins connected to the liver. Therefore anesthesiologists must prepare large bored central venous lines and transfusion materials for massive hemorrhage. Massive hemorrhage itself during liver transplantation is a life threatening condition and it causes complication like secondary pulmonary edema, which will be very fetal if it does not respond to classical treatment. Therefore the hemorrhagic situation must be monitored continuously and treated properly. We report this case because the authors experienced massive pulmonary edema right after massive hemorrhage followed by cardiopulmonary resuscitation during liver transplantation and coped with venoarterial (VA) bypass, which improved hypoxia and hypercarbia caused by pulmonary edema.