A comparison of sevoflurane with halothane,enflurane, and isoflurane on bronchoconstriction caused by histamine

This study was conducted to assess the effect of sevoflurane on lung resistance and compliance, and its responsiveness to histamine. We studied eight dogs to compare the effect of sevoflurane, isoflurane, enflurane, and halothane on bronchoconstriction caused by histamine. Baseline values of pulmonary resistance (R_L) and dynamic pulmonary compliance (C_dyn) were measured prior to administration of histamine. Histamine (2, 4, and 8 μg · kg⁻¹) were administered iv, and the values of R_L and C_dyn at the time of peak effect were recorded. Under 1 or 2 MAC anaesthesia, sevoflurane as well as the other three anaesthetics had no bronchoactive effects. The four anaesthetics, including sevoflurane, demonstrated inhibitory effect on increases in R_L and decreases in C_dyn caused by histamine. At 1 MAC anaesthesia, % changes in R_L caused by 2, 4, or 8 μg · kg⁻¹ of histamine were 38 ± 11, 85 ± 21, or 132 ± 24% (mean ± SE) for halothane, and 65 ± 11, 132 ± 15, or 172 ± 19% for sevoflurane, respectively. Sevoflurane was less effective than halothane in preventing increases in R_L. In preventing decreases in C_dyn, sevoflurane was less effective than halothane only at 8 μg · kg⁻¹ of histamine under 1 and 2 MAC anaesthesia. There was no difference in attenuating effect on changes in R_L and C_dyn between sevoflurane and isoflurane or enflurane. We concluded that sevoflurane was less potent than halothane in attenuating changes in R_L and C_dyn in response to iv histamine. Cette étude a été réalisée dans le but d’évaluer les effets du sévoflurane sur la résistance et la compliance pulmonaires en réponse à l’histamine. Les effets du sévoflurane, de l’isoflurane, de l’enflurane et de l’halothane sur la bronchoconstriction induite par l’histamine sont comparés sur huit chiens. Avant l’administration d’histamine, on mesure les valeurs initiales de la résistance (R_L) et de la compliance dynamique (C_dyn) pulmonaires. L’histamine (2, 4, 8 μg · kg⁻¹) est administrée par la voie veineuse et les valeurs maximales de la R_L et de la C_dyn sont enregistrées. Les quatre anesthésiques, dont le sévoflurane inhibent l’augmentation de la R_L et la diminution de la C_dyn provoquées par l’histamine. A MAC 1 d’anesthésie, les pourcentages de changement de R_L produits par 2, 4, ou 8 μg · kg⁻¹ d’histamine sont respectivement de 38 ± 11, 85 ± 21, ou 132 ± 24% (moyenne + SD) pour l’halothane, et de 65 ± 11, 132 ± 15, ou 172 ± 19% pour le sévoflurane. Le sévoflurane est moins efficace que l’halothane pour prévenir les augmentations de R_L. Le sévoflurane est moins efficace pour prevenir la diminution de C_dyn mais seulement à 8 μg · kg⁻¹ d’histamine sous anesthésie à MAC 1 et 2. Le sévoflurane, l’halothane et l’isoflurane ne sont pas de différents pour amortir les changements de R_L et C_dyn. Nous concluons que le sévoflurane est moins puissant que l’halothane pour diminuer la réponse à l’histamine de la R_L et de la C_dyn.     

Electrocardiographic Standard for the Diagnosis of Right Ventricular Hypertrophy in Complete Right Bundle Branch Block

It is generally considered that in complete right bundle branch block, the electrocardiographic standard for the diagnosis of right ventricular hypertrophy is not applicable. According to Cohen's criteria, right ventricular overload exists if thallium-201 myocardial perfusion demonstrates the right ventricular wall, and in this light we attempted to reassess the validity of the electrocardiographic standard for right ventricular hypertrophy. Twenty-three children with complete right bundle branch block (abbreviated as CRBBB) were evaluated. The agreement and disagreement ratios of the electrocardiographic standard with Cohen's criteria was 20/23 and 3/23 respectively. Even in patients without intracardiac anomalies, right ventricular overload was suspected by Cohen's criteria. The electrocardiographic standard was in agreement with Cohen's criteria in most of these patients.     

A case of aneurysmal subarachnoid hemorrhage associated with bilateral common carotid artery occlusion

Cerebral aneurysm may occur in some cases of major cerebral artery occlusion. However, according to our search of the literature, only four cases of aneurysmal subarchnoid hemorrhage (SAH) associated with bilateral common carotid artery occlusion (CCAO) have been reported in addition to the case we report here with a summary of the previously reported cases. A healthy 82-year-old female was found unconscious and admitted to our hospital where her neurological state was diagnosed as Hunt & Kosnik grade II, World Federation of Neurosurgical Societies grade II. General physical examination yielded no abnormal findings. A computed tomography (CT) scan of the head revealed a subarachnoid hemorrhage (Fisher's classification group 3). An aortogram demonstrated the presence of both vertebral arteries (VA), but the origins of the common carotid arteries (CCAS) were not visible at all. The left vertebral angiogram (VAG) revealed anastomosis between the muscle branch of the VA and the occipital artery, with retrograde blood flow through the external carotid artery supplying the internal carotid artery (ICA). These findings were also visible on the right VAG, but there was severe stenosis of the C2 portion of the right ICA. The right enlarged posterior communicating artery (Pcom) supplied the right ICA. Two saccular aneurysms arising from the junction of the right posterior cerebral artery (PCA) and the enlarged right Pcom and the P2 segment of right PCA, respectively were also observed. Aneurysm formation in this case was probably caused by hemodynamic stress secondary to bilateral CCAO induced by arteriosclerosis.     

Quantification of the degradation products of sevoflurane using four brands of CO2 absorbent in a standard anesthetic circuit

Purpose. CO₂ absorbents convert sevoflurane to fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether (compound A), whose toxicity in rats raises concern regarding the safety of sevoflurane in a low-flow system. The type of CO₂ absorbent is one of factors that affect compound A concentration in the anesthetic circuit. The aim of the present study was to investigate the concentration of compound A in an anesthetic model circuit following the use of different brands of soda lime and Baralyme. Methods. We measured the concentrations of compound A in four different brands of CO₂ absorbent using a low-flow (1 l·min⁻¹ fresh gas) model circuit in which 2% sevoflurane was circulated. Sodasorb II, Baralyme, Sofnolime and Wakolime-A were used as CO₂ absorbents. The concentration of compound A was measured hourly, and the temperature of the CO₂ absorbent was monitored. Results. The maximum concentration of compound A in the circuit was highest for Baralyme (25.5 ± 0.6 ppm) (mean ± SD), followed by Sodasorb II (18.9 ± 1.6 ppm), Wakolime-A (16.1 ± 0.7 ppm), and Sofnolime (15.8 ± 1.4 ppm). The maximum temperature was 50.8 ± 1.3°C for Baralyme, 48.8 ± 1.3°C for Wakolime-A, 47.0 ± 1.4°C for Sodasorb II, and 43.5 ± 3.9°C for Sofnolime. Conclusion. The relative concentrations of compound A in the low-flow circuit were Baralyme > Sodasorb II > Wakolime-A = Sofnolime. Received: August 27, 1999 / Accepted: January 13, 2000     

Effects of estrogens and metabolites on endometrial carcinogenesis in young adult mice initiated with N-ethyl-N'-nitro-N-nitrosoguanidine

The present study assessed effects of estrogens and their steroid metabolites on the endometrial carcinogenesis in young adult mice initiated with N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). A total of 272 female CD-1 (ICR) mice were used and equally divided into 17 groups. Mice were implanted cholesterol pellets to the back subcutis at 9 weeks of age. Pellets contained nothing (control) or one of the experimental agents, three different estrogens and their 13 different steroid metabolites, at a concentration of 0.5% (w/w). At 10 weeks of age, mice were given a single intra-uterine administration of ENNG at a dose of 25 mg/kg body weight. When reaching the 30 weeks of age (20 weeks after the ENNG treatment), mice were sacrificed to assess the development of endometrial proliferative lesions. While endometrial proliferative lesions, including hyperplasias and adenocarcinomas, were observed in all groups, the incidences of hyperplasias in the groups treated with 2-hydroxyestriol, 2-methoxyestradiol, 2-methoxyestriol and 16-epiestriol were significantly higher than that in the control group. On the other hand, adenocarcinomas were significantly developed in the groups treated with estrone, estradiol, estriol, 16beta-hydroxyestrone, 16alpha-hydroxyestrone and 17-epiestriol. These results indicate that, on the endometrial carcinogenesis in mice initiated with ENNG, estrogens and their metabolites belonging to the 16alpha-hydroxylation pathway and the upstream of the 16beta-hydroxylation pathway exert both promoting and progressing effects, whereas, the estrogen metabolites belonging to the 2- and 4-hydroxylation pathways (catechol estrogens) and the downstream of the 16beta-hydroxylation pathway exert only promoting or no effects. It is thus suggested that a metabolic profile of estrogens may be crucial for the endometrial carcinogenesis and that the rate of the 16alpha-hydroxylation may be associated with the increased carcinogenic risks of estrogens on the endometrium.     

A case of tuberculous granulomatous mediastinitis and constrictive pericarditis simulating malignant mediastinal tumor

A case is 40-year-old man. He presented anterior chest pain. Pericardial effusion was pointed out and a tuberculin skin test was positive. Tuberculous pericarditis was highly suspected, so INH and RFP were medicated. After 6-month medication pericardial effusion decreased, but right pleural effusion appeared on chest X-ray. Chest CT revealed a thickening of pericardium extend to anterior mediastinal mass. Echocardiogram revealed a pressure gradient in right ventricle, which was compressed by the thickened pericardium. We underwent median sternotomy in order to rule out neoplastic diseases. Intraoperative pathologic diagnosis was granulomatous mediastinitis and pericarditis, so we resected granuloma as much as possible to decompress the heart. Although Mycobacterium tuberculosis was not found in the resected granuloma, it was most probable pathogen. He received additional antituberculous chemotherapy for 6 months.     

Acceleration of Methaemoglobin Reduction by Riboflavin in Human Erythrocytes

The effect of riboflavin on nitrite treated erythrocytes from normal subjects and patients with hereditary methaemoglobinaemia due to the deficiency of NADH-cytochrome b₅ reductase was studied in the presence of glucose, 2-deoxy-d-glucose or lactate. When glucose or 2-deoxy-d-glucose was used as a substrate for these erythrocytes, the rate of methaemoglobin reduction in these cells was accelerated more than two-fold in the presence of riboflavin. The acceleration was dependent on the concentration of riboflavin and was suppressed by the addition of atebrin. The stimulative effect of riboflavin was, however, not observed when lactate was used in place of glucose or 2-deoxy-d-glucose. On the basis of these results, the acceleration of methaemoglobin reduction by riboflavin was considered to be due to the activation of NADPH-flavin reductase (Yubisui et al , 1977) in erythrocytes by the reagent. The availability of riboflavin for patients with methaemoglobinaemia due to the deficiency of NADH-cytochrome b₅ reductase and for those with toxic methaemoglobinaemia is discussed in relation to methaemoglobin reducing systems in erythrocytes.     

A new non-trocar system for 25-gauge transconjunctival pars plana vitrectomy

PURPOSE: To introduce a new non-trocar system for 25-gauge transconjunctival pars plana vitrectomy (PPV). DESIGN: Study of a new surgical instrument. METHODS: This new non-trocar system for 25-gauge transconjunctival PPV consists of a contact lens ring featuring four projections containing 1.0-mm diameter holes located 3.0 mm from the ring edge, a wedge-shaped 25-gauge infusion cannula, and two plugs. RESULTS: The ring is fixed with 7-0 silk sutures at the 3- and 9-o'clock positions on the limbus. Using the 25-gauge needle, three conjunctival and scleral incisions (n = 3) are made at the projection holes located inferotemporally, superonasally, and superotemporally. No intra- or postoperative complications were encountered in 14 patients treated by this non-trocar 25-gauge transconjunctival PPV. CONCLUSION: Using the system introduced here, 25-gauge transconjunctival PPV can be performed without suturing sclerotomies and without intra- or postoperative complications.