Analysis of Infusion Patterns of Propofol and Remifentanil During Rigid Bronchoscopy Under Total Intravenous Anesthesia.

OBJECTIVES: We analyzed the dosage pattern of anesthetic drugs administered to maintain anesthesia during rigid bronchoscopy. METHODS: We enrolled a total of 81 patients who underwent rigid bronchoscopy under total intravenous anesthesia between April 2015 and March 2019. Anesthesia was maintained using propofol (target brain concentration 2.0 - 6.0 µg/mL) and remifentanil (target brain concentration 2.0 - 6.0 ng/mL). We analyzed the dosage patterns of the anesthetic agents during the procedure, as well as the changes in the dose of the anesthetic agents and the number of procedures repeated in the same patient. RESULTS: The dose of propofol administered per minute to maintain anesthesia was inversely correlated with the total operation time (r2 = 0.355, ß = -0.067, P < 0.000) but was not significantly correlated with the number of times the procedure was repeated. The dose of remifentanil did not significantly differ during repeated procedures in the same patient. CONCLUSIONS: The dose of propofol infusion tended to decrease over time during the rigid bronchoscopy procedure. This pattern was specific to propofol but not to remifentanil using TIVA. Understanding the pharmacokinetic properties of anesthetic drugs will help in their appropriate administration.

Estimation of the effect-site equilibration rate constant using the time-to-peak effect of muscle relaxants measured by train-of-four stimulation during general anesthesia induction.

BACKGROUND: The concept of the effect-site concentration of anesthetic agents is important. The effect compartment model can be explained using the concepts of effect-site concentration and effect-site equilibration rate constant (ke0). This study confirms that the time-to-peak effect (tpe ) can be measured easily in clinical practice by applying a priming dose and train-of-four (TOF) during general anesthesia induction, and ke0 can be calculated from the tpe of the four muscle relaxants that are commonly used in general anesthesia. METHODS: Eighty patients who received general anesthesia were divided into the succinylcholine, rocuronium, atracurium, or vecuronium groups. Priming doses of muscle relaxants were administered. The effects of muscle relaxants were quantified by recording the twitch response of the adductor pollicis muscle after stimulating the ulnar nerve. The tpe was measured at the lowest TOF value. ke0 was calculated from the measured tpe . RESULTS: The ke0 values of the succinylcholine, rocuronium, atracurium, and vecuronium groups were 0.076 (0.030)/min, 0.228 (0.122)/min, 0.062 (0.011)/min, and 0.077 (0.019)/min, respectively. CONCLUSIONS: It is possible to estimate ke0 from the tpe of muscle relaxants using a priming dose and TOF during general anesthesia induction.

Evaluation of Respiratory Dynamics in an Asymmetric Lung Compliance Model.

BACKGROUND: Unilateral lung hyperinflation develops in lungs with asymmetric compliance, which can lead to vital instability. The aim of this study was to investigate the respiratory dynamics and the effect of airway diameter on the distribution of tidal volume during mechanical ventilation in a lung model with asymmetric compliance. METHODS: Three groups of lung models were designed to simulate lungs with a symmetric and asymmetric compliance. The lung model was composed of two test lungs, lung1 and lung2. The static compliance of lung1 in C15, C60, and C120 groups was manipulated to be 15, 60, and 120 ml/cmH2O, respectively. Meanwhile, the static compliance of lung2 was fixed at 60 ml/cmH2O. Respiratory variables were measured above (proximal measurement) and below (distal measurement) the model trachea. The lung model was mechanically ventilated, and the airway internal diameter (ID) was changed from 3 to 8 mm in 1-mm increments. RESULTS: The mean ± standard deviation ratio of volumes distributed to each lung (VL1/VL2) in airway ID 3, 4, 5, 6, 7, and 8 were in order, 0.10 ± 0.05, 0.11 ± 0.03, 0.12 ± 0.02, 0.12 ± 0.02, 0.12 ± 0.02, and 0.12 ± 0.02 in the C15 group; 1.05 ± 0.16, 1.01 ± 0.09, 1.00 ± 0.07, 0.97 ± 0.09, 0.96 ± 0.06, and 0.97 ± 0.08 in the C60 group; and 1.46 ± 0.18, 3.06 ± 0.41, 3.72 ± 0.37, 3.78 ± 0.47, 3.77 ± 0.45, and 3.78 ± 0.60 in the C120 group. The positive end-expiratory pressure (PEEP) of lung1 was significantly increased at airway ID 3 mm (1.65 cmH2O) in the C15 group; at ID 3, 4, and 5 mm (2.21, 1.06, and 0.95 cmH2O) in the C60 group; and ID 3, 4, and 5 mm (2.92, 1.84, and 1.41 cmH2O) in the C120 group, compared to ID 8 mm (P < 0.05). CONCLUSIONS: In the C15 and C120 groups, the tidal volume was unevenly distributed to both lungs in a positive relationship with lung compliance. In the C120 group, the uneven distribution of tidal volume was improved when the airway ID was equal to or less than 4 mm, but a significant increase of PEEP was observed.

Effects of Dexmedetomidine on Serum Interleukin-6, Hemodynamic Stability, and Postoperative Pain Relief in Elderly Patients under Spinal Anesthesia.

The beneficial effects of dexmedetomidine (DEX) have not been extensively investigated in elderly patients receiving spinal anesthesia. This study evaluated the effects of intravenous DEX infusion on stress and hemodynamic response, as well as on postoperative analgesia in elderly patients undergoing total knee arthroplasty (TKA). We randomly allocated 45 adult patients to 3 patient groups (n=15 each): uni-saline group patients underwent unilateral TKA with saline administration, uni-DEX group patients underwent unilateral TKA with DEX administration, and bilateral-DEX group patients underwent bilateral TKA with DEX administration. Serum interleukin-6 (IL-6) levels were significantly lower in the bilateral-DEX group than in the uni-saline group 6 and 24h postoperatively, and were negatively correlated with total DEX dosage 24h postoperatively. Bradycardia occurred more frequently in the uni-DEX and bilateral-DEX groups than in the uni-saline group. The total dose of required supplementary analgesics was significantly higher in the uni-saline group than in the uni-DEX and bilateral-DEX groups 6h postoperatively. The results indicate that perioperative intravenous DEX administration decreases postoperative serum IL-6 levels in patients undergoing bilateral TKA, and has a postoperative analgesic effect in patients undergoing unilateral or bilateral TKA.

Effect of 7, 8-dihydroxyflavone on the up-regulation of Nrf2-mediated heme oxygenase-1 expression in hamster lung fibroblasts.

The cytoprotective mechanism of 7, 8-dihydroxyflavone (DHF) against oxidative stress-induced cell damage with respect to its stimulatory effect on the expression of heme oxygenase-1 (HO-1), a potent antioxidant enzyme, was investigated in the present study. Up-regulation of HO-1 expression by DHF was both dose and time dependent in lung fibroblast V79-4 cells. DHF also increased the protein expression level of the transcription factor nuclear factor erythroid-2-related factor 2 (Nrf2), and induced the translocation of Nrf2 from the cytosol into the nucleus, leading to elevated HO-1 expression. The siNrf2 RNA-transfection attenuated HO-1 expression induced by DHF treatment. In addition, DHF induced the activation of extracellular signal-regulated kinase (ERK), while U0126 (a specific pharmacological inhibitor of ERK kinase) abrogated DHF-activated Nrf2 and HO-1 expression. This suggests that DHF increased the levels of Nrf2 and HO-1 via ERK-dependent pathways. Furthermore, DHF significantly prevented the reduction of cell viability in response to oxidative stress; however, U0126 attenuated the protective effect of DHF. Taken together, these results demonstrate that DHF protected cells from oxidative stress via the activation of an ERK/Nrf2/HO-1 signaling pathway.

A Comparison between Discrimination Indices and Item-Response Theory Using the Rasch Model in a Clinical Course Written Examination of a Medical School.

PURPOSE: The reliability of test is determined by each items' characteristics. Item analysis is achieved by classical test theory and item response theory. The purpose of the study was to compare the discrimination indices with item response theory using the Rasch model. METHODS: Thirty-one 4th-year medical school students participated in the clinical course written examination, which included 22 A-type items and 3 R-type items. Point biserial correlation coefficient (C(pbs)) was compared to method of extreme group (D), biserial correlation coefficient (C(bs)), item-total correlation coefficient (C(it)), and corrected item-total correlation coeffcient (C(cit)). Rasch model was applied to estimate item difficulty and examinee's ability and to calculate item fit statistics using joint maximum likelihood. RESULTS: Explanatory power (r2) of Cpbs is decreased in the following order: C(cit) (1.00), C(it) (0.99), C(bs) (0.94), and D (0.45). The ranges of difficulty logit and standard error and ability logit and standard error were -0.82 to 0.80 and 0.37 to 0.76, -3.69 to 3.19 and 0.45 to 1.03, respectively. Item 9 and 23 have outfit > or =1.3. Student 1, 5, 7, 18, 26, 30, and 32 have fit > or =1.3. CONCLUSION: C(pbs), C(cit), and C(it) are good discrimination parameters. Rasch model can estimate item difficulty parameter and examinee's ability parameter with standard error. The fit statistics can identify bad items and unpredictable examinee's responses.

Is It Useful and Safe to Maintain the Sitting Position During Only One Minute before Position Change to the Jack-knife Position?

BACKGROUND: Conventional spinal saddle block is performed with the patient in a sitting position, keeping the patient sitting for between 3 to 10 min after injection of a drug. This amount of time, however, is long enough to cause prolonged postoperative urinary retention. The trend in this block is to lower the dose of local anesthetics, providing a selective segmental block; however, an optimal dose and method are needed for adequate anesthesia in variable situations. Therefore, in this study, we evaluated the question of whether only 1 min of sitting after drug injection would be sufficient and safe for minor anorectal surgery. METHODS: Two hundred and sixteen patients undergoing minor anorectal surgery under spinal anesthesia remained sitting for 1 min after completion of subarachnoid administration of 1 ml of a 0.5% hyperbaric bupivacaine solution (5 mg). They were then placed in the jack-knife position. After surgery, analgesia levels were assessed using loss of cold sensation in the supine position. The next day, urination and 11-point numeric rating scale (NRS) for postoperative pain were assessed. RESULTS: None of the patients required additional analgesics during surgical manipulation. Postoperative sensory levels were T10 [T8-T12] in patients, and no significant differences were observed between sex (P = 0.857), height (P = 0.065), obesity (P = 0.873), or age (P = 0.138). Urinary retention developed in only 7 patients (3.2%). In this group, NRS was 5.0 ± 2.4 (P = 0.014). CONCLUSIONS: The one-minute sitting position for spinal saddle block before the jack-knife position is a safe method for use with minor anorectal surgery and can reduce development of postoperative urinary retention.

The neurological safety of epidural pamidronate in rats.

BACKGROUND: Pamidronate is a potent inhibitor of osteoclast-mediated bone resorption. Recently, the drug has been known to relieve bone pain. We hypothesized that direct epidural administration of pamidronate could have various advantages over oral administration with respect to dosage, side effects, and efficacy. Therefore, we evaluated the neuronal safety of epidurally-administered pamidronate. METHODS: Twenty-seven rats weighing 250-350 g were equally divided into 3 groups. Each group received an epidural administration with either 0.3 ml (3.75 mg) of pamidronate (group P), 0.3 ml of 40% alcohol (group A), or 0.3 ml of normal saline (group N). A Pinch-toe test, motor function evaluation, and histopathologic examination of the spinal cord to detect conditions such as chromatolysis, meningeal inflammation, and neuritis, were performed on the 2nd, 7th, and 21st day following administration of each drug. RESULTS: All rats in group A showed an abnormal response to the pinch-toe test and decreased motor function during the entire evaluation period. Abnormal histopathologic findings, including neuritis and meningeal inflammation were observed only in group A rats. Rats in group P, with the exception of 1, and group N showed no significant sensory/motor dysfunction over a 3-week observation period. No histopathologic changes were observed in groups P and N. CONCLUSIONS: Direct epidural injection of pamidronate (about 12.5 mg/kg) showed no neurotoxic evidence in terms of sensory/motor function evaluation and histopathologic examination.

A case of back pain caused by Salmonella spondylitis -A case report-.

Salmonella spondylitis is a rare illness, and it generally occurs in patients who have already had sickle cell anemia, and it is even rarer in patients who are without sickle cell anemia. A 61-year-old male patient was hospitalized for the evaluation of his renal function and then treatment was started for his back pain. His back pain had developed about 2 months previously without any specific trauma. Only a bulging disc was detected on the initial lumbar MRI. Regarding his fever, it was diagnosed as possible atypical pneumonia, scrub typhus, etc., and multiple antibiotic therapy was administered. At the time of transfer, the leucocytes and hs-CRP were normal and the ESR was elevated. A diagnostic epidural block was performed for his back pain, but his symptoms were not improved. Lumbar MRI was performed again and it showed findings of infective spondylitis. Salmonella D was identified on the abscess culture and so he was diagnosed as suffering from Salmonella spondylitis. After antibiotic treatment, his back pain was improved and the patient was able to walk.

Papaverine, a vasodilator, blocks the pore of the HERG channel at submicromolar concentration.

Papaverine, a vasodilator used as a therapeutic agent for a range of diseases, has been reported to increase the risk of occasional serious ventricular arrhythmias. To examine the mechanism for this effect, we herein tested the effects of papaverine on human ether-a-go-go (HERG) K channels expressed in HEK293 cells and Xenopus oocytes. Our results revealed that papaverine dose-dependently decreased the tail currents of HERG channel expressed in HEK293 cells with the IC50 and the Hill coefficient of 0.58 microM and 0.58, respectively, at +20 mV and 36 degrees C. The IC50 for the papaverine-induced blockade of HERG current in Xenopus oocytes was found to decrease progressively relative to depolarization (38.8, 30.0, and 24.8 microM at -10, +20, and +40 mV, respectively). The papaverine-induced blockade of HERG current was time-dependent; the fractional current was 0.92 +/- 0.03 of the control at the beginning of the pulse, but it declined to 0.18 +/- 0.06 after 6 seconds at a test potential of 0 mV. These results collectively indicate that papaverine blocks HERG channel in a concentration-, voltage-, and time-dependent manner. Two S6 domain mutations, Y652A and F656A, partially attenuated (Y652A) or abolished (F656A) the hERG current blockade, suggesting that papaverine blocks HERG channel at the pore of the channel. This was consistent with the computational simulation that showed papaverine interacts with Tyr652 and Phe656. Therefore, ventricular arrhythmias induced by papaverine could be resulted from the blockage of the HERG channel at the cardiac myocytes.