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Wyun Kon Park

Bio: Wyun Kon Park is an academic researcher from Yonsei University. The author has contributed to research in topics: Intubation & Sevoflurane. The author has an hindex of 13, co-authored 61 publications receiving 615 citations. Previous affiliations of Wyun Kon Park include University of Virginia Health System.
Topics: Intubation, Sevoflurane, Medicine, Airway, Oxygenation


Papers
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Journal ArticleDOI
TL;DR: This study was performed to determine if direct arterial dilating actions of propofol contribute to the drug's hypotensive actions and the effects of prop ofol were compared with those of thiopental on isolated vascular ring preparations from rat thoracic aorta and pulmonary artery.
Abstract: This study was performed to determine if direct arterial dilating actions of propofol contribute to the drug's hypotensive actions. The effects of propofol were compared with those of thiopental on isolated vascular ring preparations from rat thoracic aorta and pulmonary artery. Thoracic aortic ring responses were evaluated in the presence and absence of endothelium, indomethacin, and N omega-nitro-L-arginine methyl ester (LNAME; a specific inhibitor of endothelium-derived relaxing factor-nitric oxide [EDRF/NO] synthase). Pulmonary artery responses were investigated with intact endothelium. After the induction of active isometric force by a predetermined EC50 dose of phenylephrine for each ring, effects of propofol (30, 100, 300 microM) and thiopental (10, 30, 100 microM) were examined. Propofol caused significant vasodilation in endothelium-intact, endothelium-denuded, and LNAME-treated aortic rings. In the endothelium-intact aortic and pulmonary artery rings, the initial vasodilation due to 30 and 100 microM propofol showed gradual and partial recovery over 15 min; 300 microM propofol caused sustained vasodilation. Endothelium-denuded rings and LNAME-pretreated endothelium-intact rings showed constant and sustained vasodilation with all propofol concentrations. Propofol also caused marked vasodilation in pulmonary arteries. In contrast, thiopental had no vasodilating effect in aortic or pulmonary artery preparations. In control experiments, propofol vehicle (Intralipid) also had no effect on vascular rings. Indomethacin pretreatment induced a dose-dependent vasoconstriction by thiopental in endothelium-intact rings and decreased the vasodilation due to propofol.(ABSTRACT TRUNCATED AT 250 WORDS)

106 citations

Journal ArticleDOI
TL;DR: Myocardial depression by desflurane is due to decreasedCa2+ influx, whereas depolarization-activated sarcoplasmic reticulum Ca2+ release is modestly depressed, similar to the actions of isoflurane and sevoflURane.
Abstract: BackgroundThe effects of anesthetic concentrations of sevoflurane were studied in isolated myocardial tissue to delineate the mechanisms by which cardiac function is altered.MethodsIsometric force of isolated guinea pig ventricular papillary muscle was studied at 37 degrees C in normal and 26 mM Pot

89 citations

Journal Article
TL;DR: In this paper, the effects of sevoflurane concentrations on isolated guinea pig myocardial tissue were studied to delineate the mechanisms by which cardiac function is altered.
Abstract: Background : The effects of anesthetic concentrations of sevoflurane were studied in isolated myocardial tissue to delineate the mechanisms by which cardiac function is altered. Methods : Isometric force of isolated guinea pig ventricular papillary muscle was studied at 37°C in normal and 26 mM K + Tyrode's solution at various stimulation rates. Normal and slow action potentials were evaluated using conventional microelectrodes. Effects of sevoflurane on sarcoplasmic reticulum function in situ were also evaluated by its effect on rapid cooling contractures, which are known to activate Ca 2+ release from the sarcoplasmic reticulum, and on contractions of rat papillary muscle. Finally, Ca 2+ and K + currents of isolated guinea pig ventricular myocytes were examined using the whole-cell patch clamp technique. Results : Sevoflurane equivalent to 1.4% and 2.8% depressed guinea pig myocardial contractions to ∼85 and ∼65% of control, respectively, although the maximum rate of force development at 2 or 3 Hz and force in rat myocardium after rest showed less depression. In the partially depolarized, β-adrenergically stimulated myocardium, sevoflurane selectively depressed late peak force without changing early peak force, whereas it virtually abolished rapid cooling contractures. Sevoflurane did not alter the peak amplitude or maximum depolarization rate of normal and slow action potentials, but action potential duration was significantly prolonged. In isolated guinea pig myocytes at room temperature, 0.7 mM sevoflurane (equivalent to 3.4%) depressed peak Ca 2+ current by ∼25% and increased the apparent rate of inactivation. The delayed outward K + current was markedly depressed, but the inwardly rectifying K + current was only slightly affected by 0.35 mM sevoflurane. Conclusions : These results suggest that the direct myocardial depressant effects of sevoflurane are similar to those previously described for isoflurane. The rapid initial release of Ca 2+ from the sarcoplasmic reticulum is not markedly decreased, although certain release pathways, specifically those induced by rapid cooling, appear to be depressed. Contractile depression may be partly related to the depression of Ca 2+ influx through the cardiac membrane. The major electrophysiologic effect of sevoflurane seems to be a depression of the delayed outward K + current, which appears to underlie the increased action potential duration.

64 citations

Journal ArticleDOI
TL;DR: Deep neuromuscular block (post-tetanic count of 1-2) surgical conditions in patients undergoing laryngeal microsurgery improves, and the incidence of postoperative adverse events was not significantly different except for the less frequent occurrence of mouth dryness.
Abstract: Background Adequate neuromuscular block is required throughout laryngeal microsurgery. We hypothesized that the surgical conditions would improve under a deeper level of rocuronium-induced neuromuscular block. Methods Seventy-two patients undergoing laryngeal microsurgery were randomly allocated to either the ‘post-tetanic counts 1-2' (PTC1-2) group or the ‘train-of-four counts 1-2' (TOFcount1-2) group according to the level of neuromuscular block used. Two different doses of rocuronium (1.2 or 0.5 mg kg−1) were used after anaesthetic induction, and two respective targets of neuromuscular block (post-tetanic counts ≤2 or train-of-four count of 1 or 2) were used. Surgical conditions were assessed by the surgeon using a five-point rating scale (extremely poor/poor/acceptable/good/optimal), and clinically acceptable surgical conditions were defined as those which were rated acceptable, good, or optimal. The occurrence of vocal cord movement and postoperative adverse events was assessed. Results The surgical conditions were significantly different between the PTC1-2 and TOFcount1-2 groups (extremely poor/poor/acceptable/good/optimal: 0/2/1/7/26 and 3/10/2/14/7, respectively, P Conclusions Deep neuromuscular block (post-tetanic count of 1-2) surgical conditions in patients undergoing laryngeal microsurgery improves. Clinical trial registration: NCT01980069.

34 citations


Cited by
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Journal ArticleDOI
TL;DR: There is a correlation between the degree of difficulty and the anatomy of the oropharynx in the same patient, and any screening test which adds to ability to predict difficulty in intubation must be welcomed, as failure to intubate can potentially lead to fatality.
Abstract: This is a retrospective study of patients whose tracheas were impossible to intubate on a previous occasion. There is a correlation between the degree of difficulty and the anatomy of the oropharynx in the same patient. The study was initially on obstetric patients but was extended to nonobstetric surgical patients in order to increase the number of cases investigated. The incidence of failed intubations in the obstetric group over a 3-year period was seven out of 1980 cases, whereas in the surgical group the results were six out of 13,380 patients. Any screening test which adds to our ability to predict difficulty in intubation must be welcomed, as failure to intubate can potentially lead to fatality.

690 citations

Journal ArticleDOI
TL;DR: The Pediatric Basic and Advanced Life Support Collaborators aim to provide real-time information and guidance to parents and clinicians on how to care for their children during the neonatal intensive care unit and beyond.
Abstract: Alexis A. Topjian, MD, MSCE, Chair; Tia T. Raymond, MD, Vice-Chair; Dianne Atkins, MD; Melissa Chan, MD; Jonathan P. Duff, MD, Med; Benny L. Joyner Jr, MD, MPH; Javier J. Lasa, MD; Eric J. Lavonas, MD, MS; Arielle Levy, MD, Med; Melissa Mahgoub, PhD; Garth D. Meckler, MD, MSHS; Kathryn E. Roberts, MSN, RN; Robert M. Sutton, MD, MSCE; Stephen M. Schexnayder, MD; On behalf of the Pediatric Basic and Advanced Life Support Collaborators

567 citations

Journal ArticleDOI
TL;DR: Evidence is presented implicating the two-pore domain, pH-sensitive TASK-1 channel as a target for specific, clinically important anesthetic effects in mammalian neurons, in rat somatic motoneurons and locus coeruleus cells.
Abstract: Despite widespread use of volatile general anesthetics for well over a century, the mechanisms by which they alter specific CNS functions remain unclear. Here, we present evidence implicating the two-pore domain, pH-sensitive TASK-1 channel as a target for specific, clinically important anesthetic effects in mammalian neurons. In rat somatic motoneurons and locus coeruleus cells, two populations of neurons that express TASK-1 mRNA, inhalation anesthetics activated a neuronal K(+) conductance, causing membrane hyperpolarization and suppressing action potential discharge. These membrane effects occurred at clinically relevant anesthetic levels, with precisely the steep concentration dependence expected for anesthetic effects of these compounds. The native neuronal K(+) current displayed voltage- and time-dependent properties that were identical to those mediated by the open-rectifier TASK-1 channel. Moreover, the neuronal K(+) channel and heterologously expressed TASK-1 were similarly modulated by extracellular pH. The decreased cellular excitability associated with TASK-1 activation in these cell groups probably accounts for specific CNS effects of anesthetics: in motoneurons, it likely contributes to anesthetic-induced immobilization, whereas in the locus coeruleus, it may support analgesic and hypnotic actions attributed to inhibition of those neurons.

250 citations

Journal Article
TL;DR: It is shown that rats subjected to continuous coronary artery occlusion display characteristic signs of apoptosis solely in the ischemic myocardium after only 2.25 hours of ischemia, as illustrated by positive in situ end labeling (ISEL) of apoptotic cardiomyocyte nuclei in tissue sections and/or the presence of DNA “ladders” in agarose gels.
Abstract: Apoptosis has been observed previously in hearts subjected to either continuous ischemia or ischemia followed by reperfusion. The purpose of this study was to compare the timing and extent of apoptosis in both continuously ischemic and reperfused myocardium. We show that rats subjected to continuous coronary artery occlusion display characteristic signs of apoptosis solely in the ischemic myocardium after only 2.25 hours of ischemia, as illustrated by positive in situ end labeling (ISEL) of apoptotic cardiomyocyte nuclei in tissue sections and/or the presence of DNA “ladders” in agarose gels. In contrast, reperfusion after a 45-minute occlusion accelerated the process, with apoptosis becoming evident solely in the reperfused myocardium after only 1 hour of reperfusion. ISEL and DNA ladder intensity increased with duration of ischemia or reperfusion. The volume of myocardium in which ISEL was observed was smaller in the reperfused hearts, and the ISEL-stained nuclei represented 23% and 33% of the total nuc...

210 citations