Endotracheal intubation in horses: a study of two cuff inflation pressures, correlation with liquid aspiration, and tracheal wall damage
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Keywords:
Cuff
Endotracheal tube
Lumen (anatomy)
Volatility and low-affinity hamper an ability to define molecular targets of the inhaled anesthetics. Photolabels have proven to be a useful approach in this regard, although none have closely mimicked contemporary drugs. We report here the synthesis and validation of azi-isoflurane, a compound constructed by adding a diazirinyl moiety to the methyl carbon of the commonly used general anesthetic isoflurane. Azi-isoflurane is slightly more hydrophobic than isoflurane, and more potent in tadpoles. This novel compound inhibits Shaw2 K+ channel currents similarly to isoflurane and binds to apoferritin with enhanced affinity. Finally, when irradiated at 300 nm, azi-isoflurane adducts to residues known to line isoflurane-binding sites in apoferritin and integrin LFA-1, the only proteins with isoflurane binding sites defined by crystallography. This reagent should allow rapid discovery of isoflurane molecular targets and binding sites within those targets.
Moiety
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Euthanasia in rodents is an ongoing topic of debate due to concerns regarding the aversive nature of gases with anesthetic properties such as carbon dioxide (CO2) and isoflurane. The aim of this study was to expand upon previously published work evaluating the aversiveness of CO2 by introducing an isoflurane treatment group in parallel. Aversion was tested using a forced exposure setup and an aversion-avoidance setup. In the first part of the study, 12 naive female Sprague–Dawley rats were exposed during four consecutive days, once to each of four treatments: isoflurane, fox urine, oxygen, and CO2. In the second part of the study, 24 naive female Sprague–Dawley rats and 12 rats from the first experiment were exposed to CO2, isoflurane, or both gases. In the forced exposure study, there were no significant differences between CO2 and isoflurane treatments except in line crosses. Overall, rats were more active in the isoflurane and CO2 treatments compared to the control groups, suggesting that isoflurane and CO2 are similarly aversive. In the aversion-avoidance study, rats previously exposed to isoflurane left the dark chamber significantly earlier compared to naive rats during exposure to isoflurane. We also show that learned aversion to isoflurane is sustained for at least 15 days after initial exposure. Given this result, we suggest that CO2 is superior to isoflurane when euthanizing rodents with prior exposure to isoflurane. Overall, these results confirm previous studies which suggest that care should be taken when considering the serial use of isoflurane as an anesthetic.
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Objective To investigate the effects of isoflurane at different concentrations on the learning and memory in aged rats with vascular dementia. Methods The model of aged rats with vascular dementia was established with the method of 4-vessel occlusion (4-VO) in 60 aged SD rats (30 males and 30 females). The animals were divided into 6 groups according to the days (days 1 and 7) after isoflurane inhalation and the isoflurane concentrations (0,1.5% and 2.0%):d1 0 isoflurane group (I1,0),d1 1.5% isoflurane group (I1,1.5%),d1 2.0% isoflurane group (I1,2%),d7 0 isoflurane group (I7,0),d7 1.5% isoflurane group (I7,1.5%) and d7 2.0% isoflurane group (I7,2%). On day 1 and day 7 after isoflurane inhalation,Morris water maze testing was performed 8 times every day for 5 consecutive days. The latency of reaching platform in place navigation performance was the score of learning and the frequency of passing the position of platform within 1 min in probe trial performance was the score of memory. Results On the 1st day after isoflurane inhalation,the scores in the place navigation and probe trial performance of 1.5% and 2.0% isoflurane groups were markedly lower than those of 0 isoflurane group,of which the 2.0% isoflurane group had the lowest scores (P0.05). On the 7th day after isoflurane inhalations,no significant differences were observed in the latency and frequency among three groups (P0.05). Conclusion Isoflurane can further impair the learning and memory in aged rats with vascular dementia,only temporarily though.
Vascular dementia
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It is not known whether changing from isoflurane to desflurane during the latter part of anesthesia shows early emergence and recovery in long surgery. We therefore evaluated the effects of changing isoflurane to desflurane on emergence and recovery. Eighty-two patients were randomly assigned to receive isoflurane (Group I) or desflurane (Group D) or to change from isoflurane to desflurane anesthesia (Group X). At the point when there was an hour until the operation would end, isoflurane was replaced with 1 MAC of desflurane in Group X, and isoflurane and desflurane were maintained at 1 MAC in Groups I and D. When the operation ended, we compared the emergence and recovery characteristics among the 3 groups. Compared with Group I, Group X showed faster emergence and recovery. Group X and Group D showed similar emergence and recovery. In conclusion, changing isoflurane to desflurane during the latter part of anesthesia improves emergence and recovery.
Desflurane
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The purpose of this study is to assess the frontal and parietal ECoG spectrum (gamma range) changes during isoflurane and combined xenon-isoflurane anaesthesia in rats.Experiments were carried out on four adult male Sprague-Dawley rats (250-300 g). The anaesthesia was induced with isoflurane and maintained with isoflurane and a xenon-isoflurane mixture. The rats were maintained at two different anaesthetic depths: light (isoflurane anaesthesia) and deep (isoflurane and xenon-isoflurane anaesthesia). The frontal and the parietal cortical activity was assessed by computing the median frequency, spectral edge frequency and functional connectivity between these two areas during light and deep anaesthesia.We noticed a decrease in cortical connectivity under deep isoflurane anaesthesia and an increase in connectivity under deep xenon-isoflurane anaesthesia. Moreover, during xenon-isoflurane anaesthesia, a trend of regularity of electro-cortical activity was present compared with isoflurane anaesthesia.Xenon-isoflurane deep anaesthesia demonstrated a series of specific ECoG features regarding frontoparietal functional connectivity (gamma range connectivity increase) and regularity of the electrocortical activity compared with isoflurane anaesthesia.
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Objective
To evaluate effects of isoflurane on echocardiographic parameters of FVB/N mice and C57BL/6 mice.
Methods
VisualSonics Vevo 770 Imaging System was used to obtain echocardiographic parameters of male FVB/N and C57BL/6 mice.Effects of isoflurane on cardiac contractive function and structure in two strains of mice were compared.
Results
FVB/N mice maintained normal cardiac contractile function and cardiac structural parameters under 1% and 2% isoflurane anesthesia.But FVB/N mice could not be well anesthetized and it was hard to capture a clear and stable image under 1% isoflurane anesthesia.C57BL/6 mice maintained a good contractile function under 1% isoflurane anesthesia.But the contractile function of C57BL/6 mice was obviously inhibited under 2% isoflurane anesthesia.
Conclusions
2% isoflurane could be used in FVB/N mice.1% isoflurane could be used in C57BL/6 mice.
Key words:
Echocardiography; Isoflurane; FVB/N mice; C57BL/6 mice
Ratón
C57BL/6
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Euthanasia in rodents is an ongoing topic of debate due to concerns regarding the aversive nature of gases with anesthetic properties such as carbon dioxide (CO2) and isoflurane. The aim of this study was to expand upon previously published work evaluating the aversiveness of CO2 by introducing an isoflurane treatment group in parallel. Aversion was tested using a forced exposure setup and an aversion-avoidance setup. In the first part of the study, 12 naïve female Sprague–Dawley rats were exposed during four consecutive days, once to each of four treatments: isoflurane, fox urine, oxygen, and CO2. In the second part of the study, 24 naïve female Sprague–Dawley rats and 12 rats from the first experiment were exposed to CO2, isoflurane, or both gases. In the forced exposure study, there were no significant differences between CO2 and isoflurane treatments except in line crosses. Overall, rats were more active in the isoflurane and CO2 treatments compared to the control groups, suggesting that isoflurane and CO2 are similarly aversive. In the aversion-avoidance study, rats previously exposed to isoflurane left the dark chamber significantly earlier compared to naïve rats during exposure to isoflurane. We also show that learned aversion to isoflurane is sustained for at least 15 days after initial exposure. Given this result, we suggest that CO2 is superior to isoflurane when euthanizing rodents with prior exposure to isoflurane. Overall, these results confirm previous studies which suggest that care should be taken when considering the serial use of isoflurane as an anesthetic.
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Objective To analyze the effect of double-lumen endotracheal tube in the anesthesia process of thoracic surgeries.Methods 60 patients with thoracic surgeries were randomly divided into observation group and the control group.The double-lumen endotracheal tube was used in the observation group,and the control group used the single-lumen endotracheal tube.The difference of lung injury related factors,vital signs and the incidence of complications between the two groups were compared.Results In the comparison of vital signs,there was no significant difference between two groups (P ＞ 0.05).However,there was a significant reduced in the lung injury related factor and incidence of complications (P ＜ 0.05).Conclusions It would get a satisfactory effect to use double-lumen endotracheal tube in the anesthesia process of thoracic surgeries,with the same anesthesia effect,less lung injury and complication.
Key words:
Double-lumen endotracheal tube; Thoracic surgeries; Anesthesia process
Endotracheal tube
Lumen (anatomy)
Cardiothoracic surgery
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The volatile anesthetic isoflurane poses a number of experimental challenges in the laboratory. Due to its rapid evaporation, the open conditions of most in vitro electrophysiological recording systems make the determination of actual isoflurane concentrations a challenge. Since the absolute anesthetic concentration in solution is directly related to efficacy, concentration measurements are important to allow comparisons between laboratory and clinical studies. In this study we quantify the sources of isoflurane loss during experimentation and describe a method for the measurement of isoflurane concentrations using gas chromatography and mass spectrometry simultaneous to in vitro electrophysiological measurements. Serial samples of perfused bath solution allowed correlation of isoflurane concentrations with ongoing biological effects. Saturated physiological solutions contained 13.4 +/- 0.2 mM isoflurane and were diluted to desired "nominal" concentrations for experiments. The perfusion system established stable isoflurane concentrations within the bath by 2 minutes. However, bath isoflurane concentrations varied substantially and unpredictably between experiments. The magnitudes of such discrepancies in isoflurane concentrations spanned clinically important levels. Our studies suggest that, despite countermeasures, solution handling significantly impacted the isoflurane content in the tissue bath. The magnitude of these discrepancies appears to necessitate systematic direct measurement of bath isoflurane concentrations during most in vitro conditions.
Volatile anesthetic
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Hypothermia and isoflurane alone increase the potencies of steroidal muscle relaxants (MRs).We studied the combined influence of isoflurane and hypothermia on MR potency. Phrenic nerve-hemidiaphragm preparations of rats were mounted in modified Krebs' solution and aerated with 5% CO2-95% O2 gas mixture at 37 degrees C and 4% CO2 at 27 degrees C to maintain the CO2 content constant. Phrenic nerves were stimulated with 0.1 Hz supramaximal impulses and elicited tension of the diaphragm was recorded. Isoflurane 1% was added after stabilization of twitch tension and MR was added 60 min later. Twitch tension was reduced by 20% +/- 2.5% at 37 degrees C and 3.5% +/- 0.7% at 27 degrees C from control with only isoflurane. The IC50 (inhibitory concentration, 50%) values of the MRs decreased significantly (P < 0.05) with isoflurane at both temperatures. The ratios of the IC50 values without and with isoflurane of the benzylisoquinolinium MRs were significantly more at both temperatures (P < 0.05) indicating the enhancement of potentiation of their action by isoflurane over steroidal MRs. When the soluble concentration of isoflurane at 27 degrees C was kept similar to that of at 37 degrees C, the ratios of all the MRs were reduced significantly from the ratios at 37 degrees C, indicating a reduction of potentiation. When the partial pressure of isoflurane was kept constant at 37 degrees C and 27 degrees C, the potentiating action of the MRs by isoflurane was similar. But when the partial pressure was decreased to keep the concentration of isoflurane constant, the potentiation was reduced. The difference suggests that the partial pressure is a determinant of isoflurane's neuromuscular effect which is attenuated by hypothermia. (Anesth Analg 1995;80:1181-6)
Diaphragm (acoustics)
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