Seong Deok Kim

Remifentanil halves the EC50 of propofol for successful insertion of the laryngeal mask airway and laryngeal tube in pediatric patients.

BACKGROUND: Propofol and remifentanil are the drugs of choice for insertion of the supraglottic airway without muscle relaxants for short duration surgery. In this study, we compared propofol concentrations required for insertion of laryngeal mask way (LMA) or laryngeal tube (LT) with and without remifentanil. METHODS: We included children scheduled for surgeries lasting <2 h, and assigned them to four groups in a randomized, double-blind manner: LMA with propofol + saline (LMA-P), LT with propofol + saline (LT-P), LMA with propofol + 7.5 ng/mL remifentanil (LMA-PR), LT with propofol +7.5 ng/mL remifentanil (LT-PR). Anesthesia was conducted by target-controlled infusion in determined target effect site concentration of propofol and remifentanil with the STELPUMP program. The EC50 of propofol for airway device placement was determined using Dixons up-and-down method. The concentration of propofol for consecutive patients in each group was determined by the response of the previous patient, using increments or decrements of 0.2 &mgr;g/mL. RESULTS: In patients receiving remifentanil, propofol EC50 for insertion of a LMA was 2.57 ± 0.22 &mgr;g/mL and that of LT was 2.59 ± 0.20 &mgr;g/mL (n.s.). In patients receiving saline, the corresponding values were 5.45 ± 0.21 &mgr;g/mL and 5.58 ± 0.23 &mgr;g/mL (n.s.). Conditions were excellent in 64% (9 of 14) and 79% (11 of 14) of patients receiving remifentanil, but in patients receiving saline, the values were 18% (2 of 11) for the LMA and 40.0% (4 of 10) for the LT. CONCLUSIONS: Remifentanil 7.5 ng/mL reduced the propofol concentration required for airway insertion by half, and improved conditions for insertion. Propofol concentrations for insertion of the LMA and LT were similar.

Glial expression of the 90-kDa heat shock protein (HSP90) and the 94-kDa glucose-regulated protein (GRP94) following an excitotoxic lesion in the mouse hippocampus

Heat shock proteins (HSPs) are immediately expressed in neuronal and glial cells under various stressful conditions and play a protective role through molecular chaperones. Although several studies have been focused on the expression of HSPs, little is known about HSP90s expression in glial cells under neuropathological conditions. In this study, we evaluated the expression pattern of the glial cell‐related HSP90 and GRP94 proteins, following the induction of an excitotoxic lesion in the mouse brain. Adult mice received an intracerebroventricular injection of kainic acid; the brain tissue was then analyzed immunohistochemically for HSPs and double labeling using glial markers. HSPs expression was quantified by Western blot analysis. Excitotoxic damage was found to cause pyramidal cell degeneration in the CA3 region of the hippocampus. In the injured hippocampus, reactive microglia/macrophages expressed HSP90 from 12 h until 7 days postlesion (PL), showing maximal levels at day 1. In parallel, hippocampal reactive astrocytes showed the expression of GRP94 from 12 h until 7 days PL. In general, HSPs expression was transient, peaked at 1–3 days PL and reached basal levels by day 7. For the first time, our data demonstrate the injury‐induced expression of HSP90 and GRP94 in glial cells, which may contribute to the mechanism of glial cell protection and adaptation in response to damage, thereby playing an important role in the evolution of the glial response and the excitotoxic lesion outcome. HSP90 may provide antioxidant protective mechanisms against microglia/macrophages, whereas GRP94 may stabilize the astroglial cytoskeleton and participate in astroglial antioxidant mechanisms.

Changes of bispectral index during recovery from general anesthesia with 2% propofol and remifentanil in children.

Background : The bispectral (BIS) index is a pharmacodynamic measure of the effect of anesthesia on the central nervous system. The aim of this study was to investigate the relationship between BIS index and predicted plasma concentration of propofol delivered by target controlled infusion (TCI) during emergence in children.

The carina as a useful radiographic landmark for positioning the intraaortic balloon pump.

BACKGROUND:The aortic knob is thought to be the most useful radiographic landmark for the proper positioning of the intraaortic balloon pump (IABP) tip. However, this has not been studied formally. In this study we assessed whether the aortic knob is a reliable landmark for positioning the IABP and compared it with another potential landmark, the carina. METHODS:We measured the distance from the top of the distal aortic arch (aortic knob) to the left subclavian artery (LSCA) on three-dimensional computed tomography angiography in 100 patients. The distance from the level of the LSCA origin to the level of the carina was also measured using three-dimensional computed tomography in 150 additional patients. RESULTS:In 16% of the aortic knob study population, the LSCA to aortic knob distance was <0 cm or 0 cm. The median distance from the LSCA to the carina was 42 mm (range: 30–63 mm). In the carina study population, the origin of the LSCA was 35–55 mm above the carina in 95.3% of patients. CONCLUSION:In 16% of patients, the IABP was too close to the LSCA origin when it was placed at the aortic knob, whereas positioning the IABP at 2 cm above the carina provided an adequate position for the IABP tip (1.5–3.5 cm distal to the origin of the LSCA) in 95.3% of patients. The carina may be a more reliable landmark for positioning the IABP than the aortic knob.

Luminal ATP-induced contraction of rabbit pulmonary arteries and role of purinoceptors in the regulation of pulmonary arterial pressure

The effects of luminal ATP between rabbit pulmonary (PAs) and coronary arteries (CAs) were compared to understand the role of purinoceptors in the regulation of pulmonary arterial pressure (PAP) under hypoxia. Diameters of vessels were video analyzed under luminal perfusion. ATP-induced membrane currents and intracellular Ca2+ signals ([Ca2+]i) were compared in pulmonary (PASMCs) and coronary myocytes (CASMCs) using patch clamp and spectrofluorimetry. PAP was measured in perfused lungs under ventilation. Luminal ATP induced constriction of rabbit PAs in the presence of endothelium. In contrast, CAs showed dilating responses to luminal ATP even in the absence of endothelium. In PASMCs, both P2X-mediated inward current and P2Y-mediated store Ca2+ release were consistently observed. In contrast, CASMCs showed neither P2X nor P2Y responses. In the perfused lungs, hypoxia-induced PAP increase was decreased by suramin, a purinergic antagonist. A luminal application of α,β-meATP largely increased PAP, whereas UTP decreased PAP. The combined application of P2X- and P2Y-selective agonists (α,β-meATP and UTP) increased PAP. However, the perfusion of ATP alone decreased PAP, and the ATP-induced PAP decrease was affected neither by adenosine receptor antagonist nor by nitric oxide synthase inhibitor. In summary, although the luminal ATP constricts isolated PAs and suramin attenuated the HPV of perfused lungs, the bimodal responses of PAP to purinergic agonists indicate that the luminal ATP regulates pulmonary circulation via complex signaling interactions in situ.

Fascia iliaca compartment block reduces emergence agitation by providing effective analgesic properties in children

STUDY OBJECTIVE To determine whether fascia iliaca compartment block (FICB) reduces emergence agitation. DESIGN Prospective, randomized, blinded clinical trial. SETTING Operating room and Postanesthesia Care Unit (PACU) of a university hospital. PATIENTS 64 ASA physical status 1 and 2 pediatric patients aged three to 7 years, scheduled for orthopedic surgery involving the anterior or lateral thigh. INTERVENTIONS Patients enrolled in the FICB group received FICB immediately after the operation, while control group patients received intravenous (IV) patient/parent-controlled analgesia (PCA) with fentanyl. MEASUREMENTS Severity of agitation and pain were evaluated using the Pediatric Agitation and Emergence Delirium (PAED) scale and the Childrens Hospital of Eastern Ontario Pain Scale (CHEOPS). Data were collected at 10-minute intervals in the PACU. The results were analyzed using the t-test. MAIN RESULTS PAED scores in the FICB group were significantly lower than those of the control group on arrival at the PACU (7.3 ± 2.9 vs 10.4 ± 3.2, P < 0.001). The FICB group also had significantly lower CHEOPS pain scores than the control group, both on arrival at the PACU and 10 minutes after arrival (6.4 ± 1.5 vs 10.4 ± 1.8, P < 0.001 and 6.7 ± 1.6 vs 8.0 ± 1.4, P = 0.009, respectively). CONCLUSION In children having surgery on the thigh, FICB effectively reduced the severity of emergence agitation and postoperative pain during the immediate postoperative period.

A comparison of the end-tidal sevoflurane concentration for removal of the laryngeal mask airway and laryngeal tube in anesthetized children.

BACKGROUND: In this study we quantified and compared the optimal sevoflurane concentration required to prevent coughing or moving during or after removal of the laryngeal mask airway (LMA) and the laryngeal tube (LT) in anesthetized children. METHODS: Forty unpremedicated children, aged 8 mo to 12 yr, were randomly allocated to receive the LMA or LT. General anesthesia was induced via mask with sevoflurane and the LMA or LT was inserted. Anesthesia was maintained with sevoflurane and oxygen. At the end of surgery, a predetermined end-tidal sevoflurane concentration was maintained for at least 10 min and the LMA or LT was removed. Using Dixon’s up-down method, the concentration for LMA and LT removal was determined by adjusting the dose by a 0.2% increment. Success was defined by the absence of coughing, teeth clenching, gross purposeful movement, breath holding, laryngospasm, and desaturation. RESULTS: The end-tidal concentration of sevoflurane to achieve successful LMA removal in 50% of children was 1.90%, in 95% of children was 2.15%. For the LT, the concentrations were 1.83% and 2.00%. The 50% effective dose values did not differ significantly between groups. CONCLUSIONS: LMA and LT removal in 95% of anesthetized children (aged 8 mo to 12 yr) can be safely accomplished without coughing, moving, or any other airway complications at 0.86 and 0.80 minimum alveolar anesthetic concentration, respectively, and a similar concentration should be used for removal of the LT or LMA in children.

Effects of ATP and LTC4 on hypoxic pulmonary vasoconstriction in isolated rat lungs

BACKGROUND Hypoxic pulmonary vasoconstriction (HPV) is unique to pulmonary circulation but the mechanism remains elusive. Red blood cells (RBCs) are known to augment HPV and to release more ATP as oxygen content falls. Leukotrienes constrict smooth muscle and could be important for the regulation of the pulmonary circulation. Hence we hypothesized that ATP and leukotrienes are mediators of HPV produced during acute alveolar hypoxia. METHODS In forty Sprague-Dawley rats, lungs were isolated and perfused. We administered ATP (10 micrometer) to the ATP group (n = 8), the ATP antagonist, suramin (100 micrometer) to the suramin group (n = 8), leukotriene C4 (LTC4, 5 microgram) to the LTC4 group (n = 8), the LTC4 antagonist, LY171883 (20 micrometer) to the LY171883 group (n = 8), and LTC4 (5 microgram) + ATP (10 micrometer) to the LTC4 + ATP group (n = 8) during normoxic ventilation. HPV responses were induced by three hypoxic challenges for 5 minutes separated by 5 minutes of ventilation with a normoxic gas mixture. Baseline pulmonary artery pressure change after exposure to each drug and hypoxic pressor response between a period 21% normoxic gas ventilation and that of 3% hypoxic gas ventilation were measured. RESULTS ATP and LTC4 + ATP increased baseline pulmonary artery pressures but LTC4 did not alter it. ATP did not affect hypoxic pressor response. Suramin, LY171883 and LTC4 + ATP inhibited the pressor response to hypoxia. LTC4 increased hypoxic pressor response. CONCLUSIONS In isolated rat lungs, HPV may be mediated by ATP and LTC4 appears more likely to be a modulator than a mediator of HPV.

Effects of ATP and LTC4on hypoxic pulmonary vasoconstriction in isolated rat lungs

BACKGROUND Hypoxic pulmonary vasoconstriction (HPV) is unique to pulmonary circulation but the mechanism remains elusive. Red blood cells (RBCs) are known to augment HPV and to release more ATP as oxygen content falls. Leukotrienes constrict smooth muscle and could be important for the regulation of the pulmonary circulation. Hence we hypothesized that ATP and leukotrienes are mediators of HPV produced during acute alveolar hypoxia. METHODS In forty Sprague-Dawley rats, lungs were isolated and perfused. We administered ATP (10 micrometer) to the ATP group (n = 8), the ATP antagonist, suramin (100 micrometer) to the suramin group (n = 8), leukotriene C4 (LTC4, 5 microgram) to the LTC4 group (n = 8), the LTC4 antagonist, LY171883 (20 micrometer) to the LY171883 group (n = 8), and LTC4 (5 microgram) + ATP (10 micrometer) to the LTC4 + ATP group (n = 8) during normoxic ventilation. HPV responses were induced by three hypoxic challenges for 5 minutes separated by 5 minutes of ventilation with a normoxic gas mixture. Baseline pulmonary artery pressure change after exposure to each drug and hypoxic pressor response between a period 21% normoxic gas ventilation and that of 3% hypoxic gas ventilation were measured. RESULTS ATP and LTC4 + ATP increased baseline pulmonary artery pressures but LTC4 did not alter it. ATP did not affect hypoxic pressor response. Suramin, LY171883 and LTC4 + ATP inhibited the pressor response to hypoxia. LTC4 increased hypoxic pressor response. CONCLUSIONS In isolated rat lungs, HPV may be mediated by ATP and LTC4 appears more likely to be a modulator than a mediator of HPV.

Measuring depth of anesthesia with EEG and ECG in children

BACKGROUND Heart rate is tightly controlled by brain. If activity of brain and electroencephalograph (EEG) are changed by anesthetics, electrocardiograph (ECG) might be changed. We investigated whether there is a correlation between EEG and ECG, ECG could replace EEG as a monitor for depth of anesthesia. METHODS We recruited 50 patients, aged 2-8 years. Inspired and expired end-tidal sevoflurane concentrations were held constant at 1.0 or 2.5 vol%, after which ECG and EEG were obtained for 15 minutes. Total power (TP), low-frequency power (LFP), high-frequency power (HFP), approximate entropy (ApEn), and Hurst exponent (H) were calculated from the ECG. The relationship between EEG and ECG indices at the two sevoflurane concentrations was measured by Pearsons correlation coefficient. RESULTS As anesthesia deepened, ApEn, H of ECG and beta wave decreased and those of delta and theta increased in 4 channels. In FP2, changes of beta and theta wave were negatively correlated with ApEn and H of ECG (P < 0.05), and changes of delta wave was positively correlated with ApEn (P < 0.05) and H (P < 0.01). In F8, changes of beta and theta wave were negatively correlated with ApEn (P < 0.05) and only theta wave was negatively correlated with H (P < 0.05). In C4, change of delta wave was positively correlated with ApEn (P < 0.001) and H (P < 0.05). CONCLUSIONS EEG and ECG indices are correlated during sevoflurane anesthesia in children, and ECG-derived indices could possibly be used to monitor depth of anesthesia.