Seok Hwa Yoon

Effects of intraoperative low dose ketamine on remifentanil-induced hyperalgesia in gynecologic surgery with sevoflurane anesthesia

Background Remifentanil is useful during general anesthesia because of its rapid onset and short acting time. However, some studies report that due to opioid-induced hyperalgesia (OIH) and tolerance, remifentanil also increases early postoperative pain. The occurrence of OIH and opioid-induced tolerance is mainly thought to be due to central sensitization by the activation of NMDA receptors. Therefore, we investigated the effects of continuous infusion of ketamine, an NMDA receptor antagonist, on postoperative pain and the quantity of opioids used. Methods 40 patients scheduled to undergo laparoscopic gynecologic surgery were randomly allocated into two groups. Anesthesia was equally maintained with sevoflurane and 4 ng/ml of remifentanil in all patients. Ketamine (0.3 mg/kg) was injected and followed with a continuous dosage of 3 µl/kg/min in the ketamine group (n = 20) while the control group was injected and infused with an equal amount of normal saline. We compared postoperative VAS up to 7 hours and morphine demand through PCA. Results Postoperative VAS and morphine demand was significantly lower in the ketamine group 2 and 3 hours after surgery, respectively. Conclusions When general anesthesia is maintained with sevoflurane and remifentanil in patients undergoing laparoscopic gynecologic surgery, continuous infusion of low dose ketamine decreased early postoperative pain and the quantity of opioids used.

Awake Glidescope® intubation in a patient with a huge and fixed supraglottic mass -A case report-.

Intubating patients with a huge, fixed supraglottic mass causing an obstruction of the glottis is difficult to most anesthesiologists. We attempted awake fiberoptic orotracheal intubation assisted by Glidescope® Videolaryngoscope (GVL) following topical anesthesia with 4% lidocaine spray and remifentanil infusion. The glottis could not be identified by the GVL view. However, by entering toward the right side of the mass with bronchoscope, the glottis was found. Due to stiffness of the mass, we were unable to further enter the area using the bronchoscope. Alternatively, we attempted to expose the glottis by GVL blade and then successfully intubated the patient by manually pressing the cricoids cartilage. GVL is nonetheless an excellent instrument in airway management compared to fiberoptic bronchoscope for patients with a huge and fixed supraglottic mass.

Docosahexaenoic acid improves vascular function via up-regulation of SIRT1 expression in endothelial cells

n-3-Polyunsaturated fatty acids (PUFAs) protect against myocardial infarction, arteriosclerosis and high blood pressure by stimulating endothelial nitric oxide synthase (eNOS) to increase nitric oxide (NO) production. However, the mechanism remains to be elucidated. This study investigated the role of SIRT1 in the protective effects of docosahexaenoic acid (DHA) in vascular endothelial cells. Exposure of human umbilical vein endothelial cells (HUVECs) to 0.3-30 μM DHA did not affect cell viability, and DHA treatment dose-dependently increased SIRT1 expression. The DHA-mediated increase in SIRT1 expression induced eNOS deacetylation, increasing endothelial NO. However, inhibition of SIRT1 inhibited DHA-mediated increases in NO production. This effect was mediated via deacetylation of lysines 496 and 506 in the eNOS calmodulin-binding domain. The effects of DHA were also demonstrated in rat aortic rings, in which DHA treatment increased SIRT1 expression and bioavailable NO. Our results demonstrate that SIRT1 plays an important role in DHA-mediated increases in bioavailable NO via decreased eNOS acetylation.

Concerns of the anesthesiologist: anesthetic induction in severe sepsis or septic shock patients

Septic patients portray instable hemodynamic states because of hypotension or cardiomyopathy, caused by vasodilation, thus, impairing global tissue perfusion and oxygenation threatening functions of critical organs. Therefore, it has become the primary concern of anesthesiologists in conducting anesthesia (induction, maintenance, recovery, and postoperative care), especially in the induction of those who are prone to fall into hemodynamic crisis, due to hemodynamic instability. The anesthesiologist must have a precise anesthetic plan based on a thorough preanesthetic evaluation because many cases are emergent. Primary circulatory status of patients, including mental status, blood pressure, urine output, and skin perfusion, are necessary, as well as more active assessment methods on intravascular volume status and cardiovascular function. Because it is difficult to accurately evaluate the intravascular volume, only by central venous pressure (CVP) measurements, the additional use of transthoracic echocardiography is recommended for the evaluation of myocardial performance and hemodynamic state. In order to hemodynamically stabilize septic patients, adequate fluid resuscitation must be given before induction. Most anesthetic induction agents cause blood pressure decline, however, it may be useful to use drugs, such as ketamine or etomidate, which carry less cardiovascular instability effects than propofol, thiopental and midazolam. However, if blood pressure is unstable, despite these efforts, vasopressors and inotropic agents must be administered to maintain adequate perfusion of organs and cellular oxygen uptake.

A comparative study on the usefulness of the Glidescope or Macintosh laryngoscope when intubating normal airways

Background The Glidescope Videolaryngoscope (GVL) is a newly developed video laryngoscope. It offers a significantly improved laryngeal view and facilitates endotracheal intubation in difficult airways, but it is controversial in that it offers an improved laryngeal view in normal airways as well. And the price of GVL is expensive. We hypothesized that intubation carried out by fully experienced anesthesiologists using the GVL with appropriate pre-anesthetic preparations offers an improved laryngeal view and shortened intubation time in normal airways. Therefore, the aim of this study was to compare the GVL with the Macintosh laryngoscope in normal airways and to determine whether GVL can substitute the Macintosh laryngoscope. Methods This study included 60 patients with an ASA physical status of class 1 or 2 requiring tracheal intubation for elective surgery. All patients were randomly allocated into two groups, GVL (group G) or Macintosh (group M). ADS (airway difficulty score) was recorded before induction of anesthesia. The anesthesiologist scored vocal cord visualization using the percentage of glottic opening (POGO) visible and the subjective ease of intubation on a visual analogue scale (VAS). The time required to intubate was recorded by an assistant. Results There was a significant increase in POGO when using the GVL (P < 0.05). However, there was no difference in the time required for a successful tracheal intubation using the GVL compared with the Macintosh laryngoscope. The VAS score on the ease of intubation was significantly lower for the GVL than for the Macintosh laryngoscope (P < 0.05). Conclusions GVL could be a first-line tool in normal airways.

The effect on respiratory mechanics when using a Jackson surgical table in the prone position during spinal surgery

Background Respiratory dynamics may be monitored and evaluated indirectly by measuring the peak inspiratory pressure and plateau pressure. In this study, the respiratory dynamics of patients undergoing spinal surgery using a Jackson surgical table were observed with a device after converting their position from supine to prone. The effects of the dynamic compliance and airway resistance were observed from the changes in peak inspiratory pressure and plateau. Methods Twenty five patients were selected as subjects scheduled to undergo lumbar spine surgery. After intubation, the patients were ventilated mechanically with a tidal volume of 10 ml/kg and a respiration rate of 10/min. Anesthesia was maintained with sevoflurane 1.5%, nitrous oxide 2 L/min and oxygen 2 L/min. The peak inspiratory pressure, plateau pressure, resistance, compliance, arterial oxygen tension, carbon dioxide tension, heart rate and arterial blood pressure were measured at 10 minutes after the induction of anesthesia. These parameters were measured again 10 minutes after placing the patient in the prone position. Results The prone position did not significantly affect the arterial oxygen tension, carbon dioxide tension, blood pressure and heart rate, but significantly increased the peak inspiratory pressure and resistance and decreased the dynamic compliance. Conclusions The peak inspiratory pressure was increased using a Jackson surgical table to minimize the abdominal pressure when converting from the supine to prone position. This might be due to a decrease in lung and chest compliance as well as an increase in airway resistance.

Sevoflurane Exposure during the Critical Period Affects Synaptic Transmission and Mitochondrial Respiration but Not Long-term Behavior in Mice

Background: Anesthesia during the synaptogenic period induces dendritic spine formation, which may affect neurodevelopment. The authors, therefore, evaluated whether changes in synaptic transmission after dendritic spine formation induced by sevoflurane were associated with long-term behavioral changes. The effects of sevoflurane on mitochondrial function were also assessed to further understand the mechanism behind spinogenesis. Methods: Postnatal day 16 to 17 mice were exposed to sevoflurane (2.5% for 2 h), and synaptic transmission was measured in the medial prefrontal cortex 6 h or 5 days later. The expression of postsynaptic proteins and mitochondrial function were measured after anesthesia. Long-term behavioral changes were assessed in adult mice. Results: Sevoflurane increased the expression of excitatory postsynaptic proteins in male and female mice (n = 3 to 5 per group). Sevoflurane exposure in male mice transiently increased miniature excitatory postsynaptic current frequency (control: 8.53 ± 2.87; sevoflurane: 11.09 ± 2.58) but decreased miniature inhibitory postsynaptic current frequency (control: 10.18 ± 4.66; sevoflurane: 6.88 ± 2.15). Unexpectedly, sevoflurane increased miniature inhibitory postsynaptic current frequency (control: 1.81 ± 1.11; sevoflurane: 3.56 ± 1.74) in female mice (neurons, n = 10 to 21 per group). Sevoflurane also increased mitochondrial respiration in male mice (n = 5 to 8 per group). However, such changes from anesthesia during the critical period did not induce long-term behavioral consequences. Values are presented as mean ± SD. Conclusions: Sevoflurane exposure during the critical period induces mitochondrial hyperactivity and transient imbalance of excitatory/inhibitory synaptic transmission, without long-lasting behavioral consequences. Further studies are needed to confirm sexual differences and to define the role of mitochondrial activity during anesthesia-induced spine formation.

External Validation of the Acute Physiology and Chronic Health Evaluation II in Korean Intensive Care Units

Purpose This study was designed to validate the usefulness of the Acute Physiology and Chronic Health Evaluation (APACHE) II for predicting hospital mortality of critically ill Korean patients. Materials and Methods We analyzed data on 826 patients who had been admitted to nine intensive care units and were included in the Fever and Antipyretics in Critical Illness Evaluation study cohort. Results Among the patients enrolled, 62% (512/826) were medical and 38% (314/826) were surgical patients. The median APACHE II score was 17 (11 to 23 interquartile range), and the hospital mortality rate was 19.5%. Age, underlying diseases, medical patients, mechanical ventilation, and renal replacement therapy were independently associated with hospital mortality. The calibration of APACHE II was poor (H=57.54, p<0.0001; C=55.99, p<0.0001), and the discrimination was modest [area under the receiver operating characteristic (aROC)=0.729]. Calibration was poor for both medical and surgical patients (H=63.56, p<0.0001; C=73.83, p<0.0001, and H=33.92, p<0.0001; C=33.34, p=0.0001, respectively), while discrimination was poor for medical patients (aROC=0.651) and modest for surgical patients (aROC=0.704). At the predicted risk of 50%, APACHE II had a sensitivity of 36.6% and a specificity of 87.4% for hospital mortality. Conclusion For Koreans, the APACHE II exhibits poor calibration and modest discrimination for hospital mortality. Therefore, a new model is needed to accurately predict mortality in critically ill Korean patients.

Facilitation of AMPA receptor-mediated steady-state current by extrasynaptic NMDA receptors in supraoptic magnocellular neurosecretory cells

In addition to classical synaptic transmission, information is transmitted between cells via the activation of extrasynaptic receptors that generate persistent tonic current in the brain. While growing evidence supports the presence of tonic NMDA current (INMDA) generated by extrasynaptic NMDA receptors (eNMDARs), the functional significance of tonic INMDA in various brain regions remains poorly understood. Here, we demonstrate that activation of eNMDARs that generate INMDA facilitates the α-amino-3-hydroxy-5-methylisoxazole-4-proprionate receptor (AMPAR)-mediated steady-state current in supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs). In low-Mg2+ artificial cerebrospinal fluid (aCSF), glutamate induced an inward shift in Iholding (IGLU) at a holding potential (Vholding) of –70 mV which was partly blocked by an AMPAR antagonist, NBQX. NBQX-sensitive IGLU was observed even in normal aCSF at Vholding of –40 mV or –20 mV. IGLU was completely abolished by pretreatment with an NMDAR blocker, AP5, under all tested conditions. AMPA induced a reproducible inward shift in Iholding (IAMPA) in SON MNCs. Pretreatment with AP5 attenuated IAMPA amplitudes to ~60% of the control levels in low-Mg2+ aCSF, but not in normal aCSF at Vholding of –70 mV. IAMPA attenuation by AP5 was also prominent in normal aCSF at depolarized holding potentials. Memantine, an eNMDAR blocker, mimicked the AP5-induced IAMPA attenuation in SON MNCs. Finally, chronic dehydration did not affect IAMPA attenuation by AP5 in the neurons. These results suggest that tonic INMDA, mediated by eNMDAR, facilitates AMPAR function, changing the postsynaptic response to its agonists in normal and osmotically challenged SON MNCs.

Thoracic paravertebral block for breast surgery in a pregnant woman -A case report-

Non-obstetrical surgery during the first trimester is stressful to both the mother and the fetus. Anesthesiologists are also stressed, not only because of the effects of surgery itself, but also because of the uncertain influences of anesthesia thrown upon on the fetus. The authors present a case of breast surgery successfully performed on a woman 8 weeks pregnant requiring removal of breast abscess by the application of thoracic paravertebral block without any complications. Thoracic paravertebral block may be a safe anesthetic method for non-obstetric surgery during early pregnancy.