Association between De Ritis ratio and intraoperative blood transfusion in patients undergoing surgical clipping of unruptured intracranial aneurysms: a single center, retrospective, propensity score-matched study.

BACKGROUND: Although elective surgery for unruptured intracranial aneurysms (UIA) has increased, few studies have evaluated the risk factors for transfusion during UIA surgery. We evaluated the association between the preoperative De Ritis ratio (aspartate transaminase/alanine transaminase) and the incidence of intraoperative transfusion in patients who had undergone surgical UIA clipping. METHODS: Patients who underwent surgical clipping of UIA were stratified into two groups according to the preoperative De Ritis ratio cutoff levels (< 1.54 and ≥ 1.54), and the propensity score (PS)-matching analysis was performed to compare the incidence of intraoperative transfusion. Logistic regression analyses were performed to determine the risk factors for intraoperative transfusion. Net reclassification improvement (NRI) and integrated discrimination improvement (IDI) analyses were performed to verify the improvement in the intraoperative transfusion predictive model upon addition of the De Ritis ratio. RESULTS: Intraoperative transfusion incidence was 15.4% (77/502). We observed significant differences in the incidence of intraoperative transfusion (16.2% vs. 39.7%, P = 0.004) between the groups after matching. In the logistic regression analyses, the De Ritis ratio ≥ 1.54 was an independent risk factor for transfusion (odds ratio [OR]: 3.04, 95% CI [1.53, 6.03], P = 0.002). Preoperative hemoglobin (Hb) value was a risk factor for transfusion (OR: 0.33, 95% CI [0.24, 0.47], P < 0.001). NRI and IDI analyses showed that the De Ritis ratio improved the intraoperative blood transfusion predictive models (P = 0.031 and P = 0.049, respectively). CONCLUSIONS: De Ritis ratio maybe a significant risk factor for intraoperative transfusion in UIA surgery.

Total Intravenous Anesthesia Protocol for Decreasing Unacceptable Movements during Cerebral Aneurysm Clipping with Motor-Evoked Potential Monitoring: A Historical Control Study and Meta-Analysis.

Injury can occur during intraoperative transcranial motor-evoked potential (MEP) monitoring caused by patient movement related to insufficient neuromuscular blocking agent use. Here, we evaluated the incidence of unacceptable movements in patients undergoing intraoperative MEP monitoring following our anesthetic protocol. We reviewed the anesthesia records of 419 patients who underwent unruptured cerebral aneurysm clipping with intraoperative MEP monitoring. The anesthetic protocol included target-controlled infusion with a fixed effect-site propofol concentration of 3 µg/mL and an adjustable effect-site remifentanil concentration of 10-12 ng/mL. We compared our findings of the intraoperative parameters and incidence of spontaneous movement and respiration with those of published meta-analysis studies. Spontaneous movement and respiration occurred in one (0.2%) patient each. The meta-analysis included six studies. The pooled proportions of spontaneous movement and respiration were 6.9% (95% confidence interval [CI], 1.3-16.5%) and 4.1% (95% CI, 0.5-14.1%), respectively. The proportion of spontaneous movement in our study was significantly lower than that in previous studies (p = 0.013), with no significant difference in spontaneous respiration (p = 0.097). Following our center's anesthesia protocol during cerebral aneurysm clipping resulted in a low incidence of spontaneous respiration and movement, indicating its safety for patients undergoing intraoperative MEP monitoring.

Association between red blood cell distribution width and mortality in patients with metastatic brain tumors: A retrospective single-center cohort study.

Metastatic brain tumor has been associated with high mortality and poor prognosis. However, information on indicators predicting surgical prognosis in patients with brain metastases is limited. This study aimed to investigate the association between preoperative red blood cell distribution width (RDW) and mortality in patients who underwent surgery for metastatic brain tumors. This study analyzed 282 patients who underwent metastatic brain tumor surgery between August 1999 and March 2020. Patients were divided into two groups based on preoperative RDW cut-off values (<13.2 and ≥13.2). The surgical outcomes were compared between the two groups. Additionally, we performed Cox regression analysis to assess the association between preoperative RDW and 1-year and overall mortality. There were significant differences in 180-day mortality (6.2% vs. 28.7%, P<0.001), 1-year mortality (23.8% vs. 46.7%, P<0.001), and overall mortality (75.0% vs. 87.7%, P=0.012) between the two groups. In the Cox regression analysis, RDW ≥ 13.2 was significantly associated with higher 1-year mortality (adjusted hazard ratio [HR], 2.14; 95% confidence interval [CI], 1.38-3.30; P<0.001) and overall mortality (HR, 1.44; 95% CI, 1.09-1.90; P=0.010). Preoperative RDW is strongly associated with high mortality in metastatic brain tumor surgery.

Anaphylactic Shock After Indocyanine Green Video Angiography During Cerebrovascular Surgery.

BACKGROUND: Indocyanine green (ICG) video angiography has been widely used in cerebrovascular surgery. ICG injection is generally safe, with a low incidence of complications. ICG-related anaphylactic reactions during neurosurgery have been rarely reported. We report the cases of 2 patients who had experienced anaphylactic shock in response to intravenous ICG injection (DID Indocyanine Green [Dongindang, Inc., Gyeonggi-do, Republic of Korea]) during intracranial aneurysm (IA) surgery. CASE DESCRIPTION: The first patient, a 69-year-old woman with an unruptured IA, had been undergoing clipping surgery under general anesthesia. Immediately after ICG injection, her blood pressure suddenly decreased from 140/80 mm Hg to 50/30 mm Hg and she developed a skin rash on her abdomen and all extremities. Chest compression was initiated, and her vital signs gradually recovered to their pre-ICG levels within 10 minutes. The second patient was a 58-year-old woman with an unruptured IA who had been undergoing clipping surgery. After ICG injection, her blood pressure had decreased from 130/80 mm Hg to 60/40 mm Hg, and a rash-like skin lesion was observed on her abdomen. After intravenous injection of norepinephrine and dexamethasone, her blood pressure recovered to its pre-ICG level within 30 minutes and remained stable thereafter. The postoperative ICG skin provocation test findings were positive for both patients; however, only 1 patient showed markedly increased serum tryptase levels. CONCLUSION: Despite the rarity of ICG-related anaphylaxis, clinicians should be aware of this unexpected, but potentially life-threatening, drug reaction in patients undergoing cerebrovascular surgery.

Association of preoperative hypoalbuminemia with postoperative acute kidney injury in patients undergoing brain tumor surgery: a retrospective study.

OBJECTIVE Hypoalbuminemia is known to be independently associated with postoperative acute kidney injury (AKI). However, little is known about the association between the preoperative serum albumin level and postoperative AKI in patients undergoing brain tumor surgery. The authors investigated the incidence of AKI, impact of preoperative serum albumin level on postoperative AKI, and death in patients undergoing brain tumor surgery. METHODS The authors retrospectively reviewed the electronic medical records and laboratory results of 2363 patients who underwent brain tumor surgery between January 2008 and December 2014. Postoperative AKI was defined according to Kidney Disease: Improving Global Outcomes Definition and Staging (KDIGO). Multivariate logistic regression analysis was used to identify demographic, preoperative laboratory, and intraoperative factors associated with AKI development. Cox proportional hazards models were used to investigate the adjusted odds ratio and hazard ratio for the association between preoperative serum albumin level and outcome variables. RESULTS The incidence of AKI was 1.8% (n = 43) using KDIGO criteria. The incidence of AKI was higher in patients with a preoperative serum albumin level < 3.8 g/dl (3.5%) than in those with a preoperative serum albumin level ≥ 3.8 g/dl (1.2%, p < 0.001). The overall mortality was also higher in the former than in the latter group (5.0% vs 1.8%, p < 0.001). After inverse probability of treatment-weighting adjustment, a preoperative serum albumin level < 3.8 g/dl was also found to be associated with postoperative AKI (OR 1.981, 95% CI 1.022-3.841; p = 0.043) and death (HR 2.726, 95% CI 1.522-4.880; p = 0.001). CONCLUSIONS The authors' results demonstrated that a preoperative serum albumin level of < 3.8 g/dl was independently associated with AKI and mortality in patients undergoing brain tumor surgery.

Cyclohexane-Coupled Bipolar Host Materials with High Triplet Energies for Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence.

Thermally activated delayed fluorescence-based organic light-emitting diodes (TADF-OLEDs) have recently attracted tremendous research interest as next-generation optoelectronic devices. However, there are a limited number of host materials with an appropriately high lowest-excited triplet energy (ET) and bipolar charge transport properties for high-efficiency TADF-OLEDs. Moreover, these host materials should have high thermal and morphological stabilities. In this study, we develop novel bipolar host materials consisting of an electron-donating 9-phenylcarbazole unit and an electron-accepting triphenylphosphine oxide, triphenylphosphine sulfide, or 2,4,6-triphenyl-1,3,5-triazine unit linked by a nonconjugated cyclohexane core. These bipolar host materials possess high glass-transition temperatures of over 100 °C and high ET values of approximately 3.0 eV. TADF-OLEDs employing these bipolar host materials could achieve high external electroluminescence quantum efficiencies of up to 21.7% together with reduced efficiency roll-off characteristics, because of expansion of the charge-recombination zone within the emission layer arising from the bipolar charge transport ability of these host materials.

Comparison of false-negative/positive results of intraoperative evoked potential monitoring between no and partial neuromuscular blockade in patients receiving propofol/remifentanil-based anesthesia during cerebral aneurysm clipping surgery: A retrospective analysis of 685 patients.

Although the elicited responses of motor evoked potential (MEP) monitoring are very sensitive to suppression by anesthetic agents and muscle relaxants, the use of neuromuscular blockade (NMB) during MEP monitoring is still controversial because of serious safety concerns and diagnostic accuracy. Here, we evaluated the incidence of unacceptable movement and compared false-negative MEP results between no and partial NMB during cerebral aneurysm clipping surgery. We reviewed patient medical records for demographic data, anesthesia regimen, neurophysiology event logs, MEP results, and clinical outcomes. Patients were divided into 2 groups according to the intraoperative use of NMB: no NMB group (n = 276) and partial NMB group (n = 409). We compared the diagnostic accuracy of MEP results to predict postoperative outcomes between both groups. Additionally, we evaluated unwanted patient movement during MEP monitoring in both groups. Of the 685 patients, 622 (90.8%) manifested no intraoperative changes in MEP and no postoperative motor deficits. Twenty patients showed postoperative neurologic deficits despite preserved intraoperative MEP. False-positive MEP results were 3.6% in the no NMB group and 3.9% in the partial NMB group (P = 1.00). False-negative MEP results were 1.1% in the no NMB group and 4.2% in the partial NMB group (P = 0.02). No spontaneous movement or spontaneous respiration was observed in either group. Propofol/remifentanil-based anesthesia without NMB decreases the stimulation intensity of MEPs, which may reduce the false-negative ratio of MEP monitoring during cerebral aneurysm surgery. Our anesthetic protocol enabled reliable intraoperative MEP recording and patient immobilization during cerebral aneurysm clipping surgery.

Adenosine-induced transient asystole during intracranial aneurysm surgery: indications, dosing, efficacy, and risks.

BACKGROUND: Several flow-arrest techniques have been introduced for the treatment of complex aneurysms that cannot be treated with conventional clipping or endovascular coil embolization. Adenosine-induced transient asystole is an alternative method of flow arrest. However, given the limited number of studies that have reported on this topic, there is no consensus regarding the dose, regimen, efficacy, and potential risks of adenosine. METHOD: A total of 22 aneurysms in 22 different patients that underwent adenosine-induced transient asystole during aneurismal neck clipping within the past 4 years were retrospectively reviewed. Adenosine was administrated intravenously in a test-incremental manner (starting with 6-12 mg and then giving additional doses as needed) in 11 patients and in an estimated manner (pre-calculated as 0.3-0.4 mg/kg) in 11 patients. RESULTS: Overall, the study consisted of 18 unruptured saccular aneurysms, three ruptured saccular aneurysms, and a ruptured pseudoaneurysm. Adenosine-induced transient asystole was used in cases of temporary clipping inability, wide necked aneurysm, deep-seated aneurysm, or a thin aneurysm wall. The number of administrations, dose (mg/kg in ideal body weight) and duration of asystole were 1-4 (mean, 2.3) times, 0.08-1.27 (mean, 0.36) mg/kg and 0-30 (mean 13) seconds in the test-incremental manner and 1-2 (mean, 1.09) times, 0.24-0.42 (mean, 0.34) mg/kg and 13-41 (mean, 24) seconds in the estimated manner, respectively. There was a linear relationship between the dose and the duration of asystole. Twenty out of 22 aneurysms were clipped successfully with adenosine-induced transient asystole. However, in the other two cases, additional suction decompression was required for the final clipping. Adenosine-related cardiologic complications occurred in two cases of self-limited atrial fibrillation during restoration of the cardiac rhythm. CONCLUSIONS: In our experience, adenosine-induced transient asystole was safe and helpful for satisfactory clipping of a complicated aneurysm. An estimated dose injection of adenosine was more convenient than the test-incremental method and did not result in serious cardiologic problems.

Endotracheal intubation by inexperienced trainees using the Clarus Video System: learning curve and orodental trauma perspectives.

BACKGROUND: The ideal alternative airway device should be intuitive to use, yielding proficiency after only a few trials. The Clarus Video System (CVS) is a novel optical stylet with a semi-rigid tip; however, the learning curve and associated orodental trauma are poorly understood. METHODS: Two novice practitioners with no CVS experience performed 30 intubations each. Each trial was divided into learning (first 10 intubations) and standard phases (remaining 20 intubations). Total time to achieve successful intubation, number of intubation attempts, ease of use, and orodental trauma were recorded. RESULTS: Intubation was successful in all patients. In 51 patients (85%), intubation was accomplished in the first attempt. Nine patients required two or three intubation attempts; six were with the first 10 patients. Learning and standard phases differed significantly in terms of success at first attempt, number of attempts, and intubation time (70% vs. 93%, 1.4 ± 0.7 vs. 1.1 ± 0.3, and 71.4 ± 92.3 s vs. 24.6 ± 21.9 s, respectively). The first five patients required longer intubation times than the subsequent five patients (106.8 ± 120.3 s vs. 36.0 ± 26.8 s); however, the number of attempts was similar. Sequential subgroups of five patients in the standard phase did not differ in the number of attempts or intubation time. Dental trauma, lip laceration, or mucosal bleeding were absent. CONCLUSIONS: Ten intubations are sufficient to learn CVS utilization properly without causing any orodental trauma. A relatively small number of experiences are required in the learning curve compared with other devices.

Dynamic optic nerve sheath diameter responses to short-term hyperventilation measured with sonography in patients under general anesthesia.

BACKGROUND: Rapid evaluation and management of intracranial pressure (ICP) can help to early detection of increased ICP and improve postoperative outcomes in neurocritically-ill patients. Sonographic measurement of optic nerve sheath diameter (ONSD) is a non-invasive method of evaluating increased intracranial pressure at the bedside. In the present study, we hypothesized that sonographic ONSD, as a surrogate of ICP change, can be dynamically changed in response to carbon dioxide change using short-term hyperventilation. METHODS: Fourteen patients were enrolled. During general anesthesia, end-tidal carbon dioxide concentration (ETCO2) was decreased from 40 mmHg to 30 mmHg within 10 minutes. ONSD, which was monitored continuously in the single sonographic plane, was repeatedly measured at 1 and 5 minutes with ETCO2 40 mmHg (time-point 1 and 2) and measured again at 1 and 5 minutes with ETCO2 30 mmHg (time-point 3 and 4). RESULTS: The mean ± standard deviation of ONSD sequentially measured at four time-points were 5.0 ± 0.5, 5.0 ± 0.4, 3.8 ± 0.6, and 4.0 ± 0.4 mm, respectively. ONSD was significantly decreased at time-point 3 and 4, compared with 1 and 2 (P < 0.001). CONCLUSIONS: The ONSD was rapidly changed in response to ETCO2. This finding may support that ONSD may be beneficial to close ICP monitoring in response to CO2 change.

Protective effects of propofol against hydrogen peroxide-induced oxidative stress in human kidney proximal tubular cells.

BACKGROUND: We investigated the protective effects of propofol in the HK-2 cell line of human kidney proximal tubular cells against hydrogen peroxide (H(2)O(2))-induced oxidative stress. METHODS: After pretreatment with different concentrations of propofol (0 µM, 10 µM, 25 µM and 50 µM) for 30 minutes, HK-2 cells were exposed to 8 mM H(2)O(2) for 4 hours. Cell death was assessed by measuring the percentage of lactate dehydrogenase (LDH) release and by counting viable cells. The nature of cell death was assessed by doubles-taining cells with fluorescein isothiocyanate-labeled Annexin V and propidium iodide, and then analyzing the cells using flow cytometry. RESULTS: After exposure to 8 mM H(2)O(2) for 4 hours, the percentage of LDH release was 45.1 ± 4.2% and the number of viable HK-2 cells was 5.2 ± 6.0%. Pretreatment with propofol suppressed H(2)O(2)-induced LDH release in a concentration-dependent manner, reducing the percentage of LDH release to 38.1 ± 5.6%, 33.5 ± 6.3%, and 26.2 ± 3.8% of the controls at 10 µM, 25 µM and 50 µM propofol, respectively. Numbers of viable cells increased following propofol pretreatment, with 11.4 ± 10.9%, 19.5 ± 16.1%, and 32.4 ± 23.3% cell survival rates after pretreatment with 10 µM, 25 µM and 50 µM propofol, respectively. Analyses of flow cytometry showed that the propofol pretreatment decreased the percentage of necrotic and late apoptotic cells. CONCLUSIONS: Propofol protects HK-2 human kidney proximal tubular cells against H(2)O(2)-induced oxidative stress.

Total intravenous anesthesia in a 10-month-old patient with congenital myotonic dystrophy undergoing endoscopic third ventriculostomy -A case report-.

Myotonic dystrophy is a rare genetic disorder characterized by muscle atrophy and weakness. Surgical treatment of this condition poses various problems for the anesthesiologist. We describe the anesthetic management of a 10-month-old infant with congenital myotonic dystrophy, who was scheduled for endoscopic third ventriculostomy under general anesthesia. Anesthesia was induced with thiopental sodium, fentanyl, and vecuronium, and thereafter maintained via continuous infusion of propofol and remifentanil. The train-of-four ratio was monitored throughout the operation, and muscle relaxation was reversed with pyridostigmine and glycopyrrolate at the end of the procedure. We show that total intravenous anesthesia using propofol and remifentanil is a satisfactory anesthetic technique in very young patients with congenital myotonic dystrophy.

Effect of isoflurane on the hearing in mice.

BACKGROUND AND OBJECTIVES: The aim of this study was to investigate the relationship between inhalation anesthetics and hearing in mice. MATERIALS AND METHODS: As inhalation anesthetics, isoflurane was used. Auditory brainstem response and distortion product otoacoustic emission were used as measurement of hearing. Mice were divided into 2 groups. 'Isoflurane group' consisted of mice that were anesthetized with an inspired concentration of 2.0 vol% isoflurane with 2 L/min of oxygen (n=10). 'Control group' consisted of mice that were anesthetized with ketamine and xylazine (n=10). RESULTS: Auditory brainstem response thresholds in mice anesthetized with ketamine and xylazine was not different from those in mice anesthetized with isoflurane. Threshold of DPOAE was higher in mice with isolurane than with ketamine and xylazine. Changes of efferent control may be induced by isoflurane and consequently change the threshold of DPOAE in mice. CONCLUSIONS: These results infer that, there was a change of central nervous system induced by inhalation anesthetics, this change also can be applied to the strategies for prevention of hearing loss.

Bilateral tension pneumothorax caused by an abrupt increase in airway pressure during cervical spine surgery in the prone position -A case report-.

Elevated peak inspiratory airway pressure (PIP) can occur during general anesthesia and is usually easily rectified. In rare circumstances it can lead to potentially fatal conditions such as tension pneumothorax. We report on a 77-year-old male patient admitted for a cervical laminoplasty. The preoperative chest radiograph showed normal findings and there was no medical history of allergy or underlying airway inflammation. Anesthesia induction and maintenance progressed uneventfully. However, 5 minutes after prophylactic antibiotic administration, PIP suddenly increased and blood pressure dropped. The operation was abandoned and the patient was moved to a supine position to perform chest radiography. Cardiac arrest occurred, and cardiopulmonary resuscitation was performed. The radiograph showed bilateral tension pneumothorax. Needle aspiration was immediately performed, and chest tubes were inserted. Ventilation rapidly improved and the vital signs normalized. The patient was discharged without sequelae on postoperative day 36.

Spinal epidural hematoma related to an epidural catheter in a cardiac surgery patient -A case report-.

The addition of thoracic epidural anesthesia to general anesthesia during cardiac surgery may have a beneficial effect on clinical outcome. However, epidural catheter insertion in a patient anticoagulated with heparin may increase the risk of epidural hematoma. We report a case of epidural hematoma in a 55-year-old male patient who had a thoracic epidural placed under general anesthesia preceding uneventful mitral valve replacement and tricuspid valve annular plasty. During the immediate postoperative period and first postoperative day, prothrombin time (PT) and activate partial thromboplastin time (aPTT) were mildly prolonged. On the first postoperative day, he complained of motor weakness of the lower limbs and back pain. An immediate MRI of the spine was performed and it revealed an epidural hematoma at the T5-6 level. Rapid surgical decompression resulted in a recovery of his neurological abnormalities to near normal levels. Management and preventing strategies of epidural hematoma are discussed.

Comparison of the effects of propofol and pentobarbital on hydrogen peroxide-stimulated hepatic SNU761 cells.

BACKGROUND: Propofol and barbiturates are both known to protect cells of several organs against ischemia/reperfusion injury, but there are few reports on any possible protective effects on human hepatocytes. We investigated the activities of both agents on human hepatic SNU761 cells under hydrogen peroxide (H(2)O(2))-induced oxidative stress. METHODS: To determine whether propofol and pentobarbital protect hepatocytes from H(2)O(2)-induced toxicity, we used SNU761 cells, a human hepatocellular carcinoma (HCC) cell line. Cells were pretreated with different dosages (1, 10, 50 microM) of propofol or pentobarbital (1, 10, 50, 100, 400 microM) 30 min before H(2)O(2) application. Lactate dehydrogenase (LDH) was measured to assess and quantify cell death. To determine the nature of cell death, treated hepatocytes were doubly stained with fluorescein isothiocyanate (FITC)-labeled Annexin V and propidium iodide (PI), and analyzed by flow cytometry. RESULTS: Pretreatment with propofol, but not pentobarbital, suppressed H(2)O(2)-induced LDH release. In Annexin V-FITC/PI binding analysis, propofol decreased the number of necrotic and late apoptotic cells, but no significant decreases in such cell numbers were seen when pentobarbital was used. CONCLUSIONS: Unlike pentobarbital, propofol, at clinical concentrations, protected SNU-761 HCC cells against oxidative stress.

Effects of propofol and etomidate on hydrogen peroxide-induced oxidative damage in hepatocyte.

BACKGROUND: The present investigation was undertaken to evaluate the protective effect of propofol and etomidate against hydrogen peroxide (H2O2) induced oxidative damage in human hepatic SNU761 cells by measuring lactate dehydrogenase (LDH). METHODS: The cell line of human hepatocellular carcinoma was grown for 24 hours in dissociated cell culture. They were divided into eight groups: negative control (NC) group with no drug administration, positive control (PC) group with H2O2 250 micrometer and other groups pretreated with propofol (P; 1, 10, 50 micrometer) or etomidate (ET; 1, 10, 50 micrometer) followed H2O2 administration. After 7 hours, cell death was assessed by morphology under the light microscope and quantified by measuring the LDH in the culture media. RESULTS: In the light microscopic findings, the intact cells were increased in all three propofol groups compared to group PC. H2O2-induced LDH production was also significantly suppressed in all three propofol groups compared to group PC (P < 0.001). There were no significant differences in the microscopic findings and LDH production between the etomidate groups and group PC. CONCLUSIONS: These results suggest that the propofol has protective effect on the hepatocyte against H2O2-induced oxidative stress.

The effect of isoflurane, halothane and pentobarbital on noise-induced hearing loss in mice.

BACKGROUND: Ear surgery using mastoid drills can lead to noise-induced hearing loss (NIHL). We investigated whether inhaled anesthetics or pentobarbital could have protective effects on NIHL in mice. METHODS: Mice were exposed to broad band white noise for 3 h per day for 3 consecutive days, with or without anesthesia, using halothane, isoflurane, or pentobarbital. The hearing level of each mouse was analyzed before exposure, and 1 day, 1, 2, and 3 Wk, and 1 mo after noise exposure by measuring auditory brainstem response thresholds. At 1 Wk after noise exposure, the organ of Corti was stained with a fluorescent isothiocyanate-conjugated phalloidin probe and a TUNEL kit. RESULTS: In the unanesthetized control group, the hearing threshold increased to 77.5 +/- 8.0 dB hearing level (HL) after noise stimulation. In the pentobarbital, isoflurane, and halothane groups, hearing threshold increased to 62.5 +/- 6.3 dB HL, 45.5 +/- 9.8 dB HL, and 39.3 +/- 6.2 dB HL, respectively, with all anesthetized groups of mice showing significantly preserved hearing compared with the control group (P < 0.05). But, in mice anesthetized with pentobarbital, hearing loss was more severe than in those treated with the inhaled anesthetics (P < 0.05). Hair cell survival was reduced in unanesthetized control mice and somewhat reduced in pentobarbital-treated mice, but largely unaffected in mice treated with inhaled anesthetics. CONCLUSIONS: These findings indicate that, while halothane, isoflurane and pentobarbital could protect mice against NIHL and hair cell damage, inhaled anesthetics were more effective.

Protective effect of isoflurane anesthesia on noise-induced hearing loss in mice.

HYPOTHESIS/OBJECTIVES: To examine the protective effect of general anesthesia with isoflurane against noise-induced hearing loss in mice. STUDY DESIGN: Animal study using noise stimulation and measurement of hearing in BALB/c mice. METHODS: Mice were exposed to 122 dB peak equivalent sound pressure level click noise for 3 hours per day for 3 consecutive days with or without anesthesia using isoflurane. Hearing levels were measured and hair cell survival ratio was observed. RESULTS: In mice without anesthesia, hearing threshold increased after noise stimulation (73.7 dB hearing level [HL]) and persisted for at least 1 month. However, in mice exposed to noise under anesthesia, hearing loss was less severe (44.1 dB HL) and had recovered more (26.5 dB HL) by one month. Histological examination showed hair cell survival was higher in anesthetized compared to non-anesthetized mice. CONCLUSION: These data indicate isoflurane general anesthesia protects against noise-induced hearing loss and tissue damage in mice.

The effect of phenytoin on rocuronium-induced neuromuscular block in the rat phrenic nerve-hemidiaphragm preparation.

Anticonvulsant therapy alters the action of nondepolarizing muscle relaxants. We determined the effects of acute and chronic administration of phenytoin on rocuronium-induced neuromuscular block using the rat phrenic nerve-hemidiaphragm preparation. Rats were divided into 3 groups: a saline control group (n = 10), an acute phenytoin-treated group (n = 30), and a chronic phenytoin-pretreated group (n = 30). Phrenic nerve-hemidiaphragm was dissected, mounted in a bath containing oxygenated Krebs solution, and the nerve was stimulated at supramaximal intensity. Single twitch responses were recorded by physiogram. In the acute phenytoin-treated group, acute effects of phenytoin were determined based on the phenytoin concentration of 1, 10, or 100 microg/mL in the bath. The chronic effects of phenytoin were determined using phrenic nerve-diaphragms from rats pretreated with phenytoin (50 mg/kg/d) for 1, 7, or 28 days. In rats with phenytoin 100 microg/mL in the bath, all concentrations of rocuronium produced twitch depression significantly different from those of other groups (P < 0.05), and the concentration-response curve shifted to the left. In rats with phenytoin 10 microg/mL in the bath, the effective concentrations for 50%, 90%, and 95% twitch depression values were significantly different from those of the control group (P < 0.05). In chronically (28 days) phenytoin-pretreated rats, the concentration-response curve significantly shifted to the right (P < 0.05). These findings show that acute administration of phenytoin augmented the neuromuscular blocking effects of rocuronium, whereas chronic phenytoin treatment causes resistance to the neuromuscular blocking effects of rocuronium in target organs.