Publications by authors named "Seungwoo Ku"

8 Publications

  • Page 1 of 1

Arrhythmia incidence and associated factors during volatile induction of general anesthesia with sevoflurane: a retrospective analysis of 950 adult patients.

Anaesth Crit Care Pain Med 2021 Jun 5;40(3):100878. Epub 2021 May 5.

Department of Anaesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. Electronic address:

Background: Sevoflurane has been used to induce anaesthesia in adults due to its suitability for airway management and haemodynamic stability. Few studies have reported arrhythmia during volatile induction with sevoflurane in adults. Here, we investigated the incidence of arrhythmia and risk factors associated with its occurrence during sevoflurane induction of anaesthesia in adults.

Patients And Methods: We retrospectively analysed 950 adult patients who underwent elective ear nose and throat surgery with volatile induction using sevoflurane between May and December 2015. The incidence of arrhythmia and the factors associated with its development were analysed.

Results: Arrhythmia was observed in 164 (17.3%) of 950 adult patients. The most frequently observed arrhythmia was sinus tachycardia (heart rate > 120 bpm) (77 patients, 47.0%). The multivariable logistic analysis showed four independent risk factors: age (odds ratio [OR] = 0.984, 95% confidence interval [CI] = 0.973-0.996, p = 0.006), coronary artery disease (OR = 3.749, 95% CI = 1.574-8.927, p = 0.003), maximal concentration (8 vol%) of sevoflurane from the start of induction (OR = 2.696, 95% CI = 1.139-6.382, p = 0.024), and maintenance of 8 vol% sevoflurane concentration after eyelash reflex loss (OR = 1.577, 95% CI = 1.083-2.296, p = 0.018). The risk of hypotension was greater in patients in whom arrhythmia occurred, although blood pressure recovered to baseline after the concentration of sevoflurane was adjusted.

Conclusions: We recommend that the sevoflurane concentration be gradually increased with continuous and vigilant electrocardiogram and blood pressure monitoring. The sevoflurane concentration should be adjusted after sufficient unconsciousness is reached.
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June 2021

Negative pressure pulmonary edema in a patient undergoing open rhinoplasty: A case report.

Medicine (Baltimore) 2021 Jan;100(1):e24240

Department of Anesthesiology and Pain Medicine.

Rationale: Negative pressure pulmonary edema (NPPE) is associated with serious postoperative complications. Compact nasal packing is always done after an open rhinoplasty procedure which makes it difficult to achieve positive pressure ventilation via a mask if NPPE arises.

Patient Concerns: A 21-year-old healthy man got an open rhinoplasty, septal perforation repair, and revisional septal reconstruction. After surgery, he became so agitated that it was difficult to calm him. We decided to remove the endotracheal tube. On arrival at the post-anesthesia care unit, he was cyanotic and his SpO2 had decreased to about 2%. We attempted positive pressure ventilation using mask bagging; however, it was ineffective due to the nasal packing.

Diagnoses: Negative pressure pulmonary edema.

Interventions: Emergent reintubation was immediately done and Ambu bagging was commenced. A considerable pinkish secretion came out of the tube. A T-piece was applied to him using 15 L/min of oxygen supply. The patient was eventually transferred to the intensive care unit of our hospital.

Outcomes: On postoperative day (POD) 1, a decision was made to extubate, and the oxygen supply was shifted to 3L/min using a venturi-mask. On POD 2, a chest posteroanterior radiograph was taken and indicated no active lung lesion. The patient was subsequently discharged without any complications. He had no symptoms on POD 6, 11, and 18 at follow-up visits to our outpatient clinic.

Lessons: Anesthesiologists should be alert to the possibility of NPPE and its treatment because of its rapid onset but positive clinical outcome if there is a proper intervention. In nasal surgery cases in particular, early re-intubation should be conducted and extubation should be done to fully awaken the patients.
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January 2021

Comparison of preoxygenation with a high-flow nasal cannula and a simple mask before intubation during induction of general anesthesia in patients undergoing head and neck surgery: Study protocol clinical trial (SPIRIT Compliant).

Medicine (Baltimore) 2020 Mar;99(12):e19525

Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Songpa-gu, Seoul, Republic of Korea.

Background: To assess the arterial oxygen partial pressure (PaO2) at defined time points during preoxygenation and to compare high-flow heated humidified nasal oxygenation with standard preoxygenation using oxygen insufflation via a facemask for at least 5 minutes, before intubation during induction of general anesthesia.

Methods: This randomized, single-blinded, prospective study will be conducted in patients undergoing head and neck surgery. After standard monitoring, the artery catheter at the radial artery or dorsalis pedis artery will be placed and arterial blood gas analysis (ABGA) for baseline values will be performed simultaneously. Each group will be subjected to 1 of 2 preoxygenation methods (high-flow nasal cannula or simple facemask) for 5 minutes, and ABGA will be performed twice. After confirming intubation, we will start mechanical ventilation and check the vital signs and perform the final ABGA.

Discussion: This trial aims to examine the trajectory of PaO2 levels during the whole preoxygenation procedure and after intubation. We hypothesize that preoxygenation with the high-flow nasal cannula will be superior to that with the face mask.

Study Registration: This trial was registered with the Clinical Trial Registry (NCT03896906;
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March 2020

Effect of Total Intravenous Anesthesia vs Volatile Induction With Maintenance Anesthesia on Emergence Agitation After Nasal Surgery: A Randomized Clinical Trial.

JAMA Otolaryngol Head Neck Surg 2019 02;145(2):117-123

Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Importance: Emergence agitation is common after nasal surgery under general anesthesia and may lead to serious consequences for the patient, including an increased risk of injury, pain, hemorrhage, and self-extubation. Despite decades of research, studies on the incidence, risk factors, and prevention of emergence agitation in adult patients are ongoing, and opinions differ on the different effects of inhalation and intravenous anesthesia.

Objective: To investigate the effect of anesthetic method on the occurrence of emergence agitation after nasal surgery.

Design, Setting, And Participants: This prospective, randomized, single-blind, clinical trial included 80 patients undergoing open rhinoplasty, septoplasty, turbinoplasty, endoscopic sinus surgery, and functional endoscopic sinus surgery under general anesthesia who were randomized to receive total intravenous anesthesia (TIVA) with remifentanil hydrochloride and propofol (n = 40) or volatile induction and maintenance of anesthesia (VIMA) with sevoflurane and nitrous oxide (n = 40) in Asan Medical Center, a tertiary referral center in Seoul, Republic of Korea. Data were collected from August 24 through October 14, 2016, and analyzed from October 26, 2016, through September 14, 2017.

Main Outcomes And Measures: The occurrence of emergence agitation defined by the following 2 individual criteria: a Richmond Agitation-Sedation Scale score of at least 1 and a Riker Sedation-Agitation Scale score of at least 5 immediately after extubation.

Results: Among the 80 patients included in the analysis (68.8% men [n = 55]; mean [SD] age, 41.6 [17.9] years), emergence agitation measured by the Richmond Agitation Sedation Scale occurred in 8 of 40 patients (20.0%) in the VIMA group and 1 of 40 (2.5%) in the TIVA group. The risk difference was 17.5 (95% CI, 3.6-31.4). Emergence agitation measured by the Riker Sedation-Agitation Scale score occurred in 10 of 40 patients (25.0%) in the VIMA group and 1 of 40 (2.5%) in the TIVA group. The risk difference was 22.5 (95% CI, 7.3-37.7).

Conclusions And Relevance: The occurrence of emergence agitation after nasal surgery under general anesthesia can be significantly reduced by using TIVA rather than VIMA.

Trial Registration: CRIS identifier: KCT0002145.
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February 2019

Differential Postoperative Effects of Volatile Anesthesia and Intraoperative Remifentanil Infusion in 7511 Thyroidectomy Patients: A Propensity Score Matching Analysis.

Medicine (Baltimore) 2016 Feb;95(7):e2764

From the Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Although remifentanil is used widely by many clinicians during general anesthesia, there are recent evidences of opioid-induced hyperalgesia as an adverse effect. This study aimed to determine if intraoperative remifentanil infusion caused increased pain during the postoperative period in patients who underwent a thyroidectomy. A total of 7511 patients aged ≥ 20 years, who underwent thyroidectomy between January 2009 and December 2013 at the Asan Medical Center were retrospectively analyzed. Enrolled patients were divided into 2 groups: group N (no intraoperative remifentanil and only volatile maintenance anesthesia) and group R (intraoperative remifentanil infusion including total intravenous anesthesia and balanced anesthesia). Following propensity score matching analysis, 2582 patients were included in each group. Pain scores based on numeric rating scales (NRS) were compared between the 2 groups at the postoperative anesthetic care unit and at the ward until 3 days postoperation. Incidences of postoperative complications, such as nausea, itching, and shivering were also compared. The estimated NRS pain score on the day of surgery was 5.08 (95% confidence interval [CI] 4.97-5.19) in group N patients and 6.73 (95% CI 6.65-6.80) in group R patients (P < 0.001). There were no statistically significant differences in NRS scores on postoperative days 1, 2, and 3 between the 2 groups. Postoperative nausea was less frequent in group R (31.4%) than in group N (53.5%) (P < 0.001). However, the incidence of itching was higher in group R (4.3%) than in group N (0.7%) (P < 0.001). Continuous infusion of remifentanil during general anesthesia can cause higher intensity of postoperative pain and more frequent itching than general anesthesia without remifentanil infusion immediately after thyroidectomy. Considering the advantages and disadvantages of continuous remifentanil infusion, volatile anesthesia without opioid may be a good choice for minor surgeries, such as thyroidectomy.
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February 2016

Electroencephalographic effects of ketamine on power, cross-frequency coupling, and connectivity in the alpha bandwidth.

Front Syst Neurosci 2014 1;8:114. Epub 2014 Jul 1.

Department of Anesthesiology, Center for Consciousness Science, University of Michigan Medical School Ann Arbor, MI, USA ; Neuroscience Graduate Program, University of Michigan Medical School Ann Arbor, MI, USA.

Recent studies of propofol-induced unconsciousness have identified characteristic properties of electroencephalographic alpha rhythms that may be mediated by drug activity at γ-aminobutyric acid (GABA) receptors in the thalamus. However, the effect of ketamine (a primarily non-GABAergic anesthetic drug) on alpha oscillations has not been systematically evaluated. We analyzed the electroencephalogram of 28 surgical patients during consciousness and ketamine-induced unconsciousness with a focus on frontal power, frontal cross-frequency coupling, frontal-parietal functional connectivity (measured by coherence and phase lag index), and frontal-to-parietal directional connectivity (measured by directed phase lag index) in the alpha bandwidth. Unlike past studies of propofol, ketamine-induced unconsciousness was not associated with increases in the power of frontal alpha rhythms, characteristic cross-frequency coupling patterns of frontal alpha power and slow-oscillation phase, or decreases in coherence in the alpha bandwidth. Like past studies of propofol using undirected and directed phase lag index, ketamine reduced frontal-parietal (functional) and frontal-to-parietal (directional) connectivity in the alpha bandwidth. These results suggest that directional connectivity changes in the alpha bandwidth may be state-related markers of unconsciousness induced by both GABAergic and non-GABAergic anesthetics.
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July 2014

Subgraph "backbone" analysis of dynamic brain networks during consciousness and anesthesia.

PLoS One 2013 15;8(8):e70899. Epub 2013 Aug 15.

Department of Physics, Pohang University of Science and Technology, Pohang-si, Gyeongsangbuk-do, South Korea.

General anesthesia significantly alters brain network connectivity. Graph-theoretical analysis has been used extensively to study static brain networks but may be limited in the study of rapidly changing brain connectivity during induction of or recovery from general anesthesia. Here we introduce a novel method to study the temporal evolution of network modules in the brain. We recorded multichannel electroencephalograms (EEG) from 18 surgical patients who underwent general anesthesia with either propofol (n = 9) or sevoflurane (n = 9). Time series data were used to reconstruct networks; each electroencephalographic channel was defined as a node and correlated activity between the channels was defined as a link. We analyzed the frequency of subgraphs in the network with a defined number of links; subgraphs with a high probability of occurrence were deemed network "backbones." We analyzed the behavior of network backbones across consciousness, anesthetic induction, anesthetic maintenance, and two points of recovery. Constitutive, variable and state-specific backbones were identified across anesthetic state transitions. Brain networks derived from neurophysiologic data can be deconstructed into network backbones that change rapidly across states of consciousness. This technique enabled a granular description of network evolution over time. The concept of network backbones may facilitate graph-theoretical analysis of dynamically changing networks.
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September 2014

Disruption of frontal-parietal communication by ketamine, propofol, and sevoflurane.

Anesthesiology 2013 Jun;118(6):1264-75

Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, Michigan 48109-5048, USA.

Introduction: Directional connectivity from anterior to posterior brain regions (or "feedback" connectivity) has been shown to be inhibited by propofol and sevoflurane. In this study the authors tested the hypothesis that ketamine would also inhibit cortical feedback connectivity in frontoparietal networks.

Methods: Surgical patients (n = 30) were recruited for induction of anesthesia with intravenous ketamine (2 mg/kg); electroencephalography of the frontal and parietal regions was acquired. The authors used normalized symbolic transfer entropy, a computational method based on information theory, to measure directional connectivity across frontal and parietal regions. Statistical analysis of transfer entropy measures was performed with the permutation test and the time-shift test to exclude false-positive connectivity. For comparison, the authors used normalized symbolic transfer entropy to reanalyze electroencephalographic data gathered from surgical patients receiving either propofol (n = 9) or sevoflurane (n = 9) for anesthetic induction.

Results: Ketamine reduced alpha power and increased gamma power, in contrast to both propofol and sevoflurane. During administration of ketamine, feedback connectivity gradually diminished and was significantly inhibited after loss of consciousness (mean ± SD of baseline and anesthesia: 0.0074 ± 0.003 and 0.0055 ± 0.0027; F(5, 179) = 7.785, P < 0.0001). By contrast, feedforward connectivity was preserved during exposure to ketamine (mean ± SD of baseline and anesthesia: 0.0041 ± 0.0015 and 0.0046 ± 0.0018; F(5, 179) = 2.07; P = 0.072). Like ketamine, propofol and sevoflurane selectively inhibited feedback connectivity after anesthetic induction.

Conclusions: Diverse anesthetics disrupt frontal-parietal communication, despite molecular and neurophysiologic differences. Analysis of directional connectivity in frontal-parietal networks could provide a common metric of general anesthesia and insight into the cognitive neuroscience of anesthetic-induced unconsciousness.
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June 2013