Isoflurane General Anesthesia Research Articles

Changes in echocardiographic indices and left ventricular strain values by two-dimensional speckle-tracking echocardiography following pre-anesthetic oral pimobendan administration compared with intravenous pimobendan in dogs.

The effects of pre-anesthetic single-dose oral pimobendan during inhalational anesthesia, including the comparison with the effects of single intravenous pimobendan under anesthesia, remain unexplored. Therefore, this study aimed to determine changes in hemodynamic and echocardiographic parameters induced by pre-anesthetic administration of oral pimobendan under isoflurane general anesthesia and to compare them with those induced by intravenous pimobendan. Thirteen clinically normal dogs (4 laboratory and 9 client-owned dogs) with no clinical signs and not on any medical treatment were included. Anesthesia was performed three times: no pimobendan (Control), oral pimobendan (PIMO PO, 0.3 mg/kg), and intravenous pimobendan (PIMO IV, 0.15 mg/kg). Echocardiographic and hemodynamic parameters were monitored at 30-min intervals in all groups. Compared to the Control group, end-systolic volume index (ESVI) and normalized left ventricular internal diameter at end-systole (LVIDSN) were significantly lower, and fractional shortening (FS) and ejection fraction (EF) were significantly higher in the PIMO PO and IV groups (p < 0.001). Global radial strain (GRS) was significantly higher in the PIMO PO and IV groups (p = 0.015). Under general anesthesia, oral pimobendan preserved LV systolic and myocardial function in a manner comparable to intravenous pimobendan. Pre-anesthetic administration of oral pimobendan can be used to compensate for cardiac systolic function in dogs who require therapeutic and diagnostic procedures under general anesthesia with potential risk of circulatory failure.

GABAergic neurons of anterior thalamic reticular nucleus regulate states of consciousness in propofol- and isoflurane-mediated general anesthesia.

The thalamus system plays critical roles in the regulation of reversible unconsciousness induced by general anesthetics, especially the arousal stage of general anesthesia (GA). But the function of thalamus in GA-induced loss of consciousness (LOC) is little known. The thalamic reticular nucleus (TRN) is the only GABAergic neurons-composed nucleus in the thalamus, which is composed of parvalbumin (PV) and somatostatin (SST)-expressing GABAergic neurons. The anterior sector of TRN (aTRN) is indicated to participate in the induction of anesthesia, but the roles remain unclear. This study aimed to reveal the role of the aTRN in propofol and isoflurane anesthesia. We first set up c-Fos straining to monitor the activity variation of aTRNPV and aTRNSST neurons during propofol and isoflurane anesthesia. Subsequently, optogenetic tools were utilized to activate aTRNPV and aTRNSST neurons to elucidate the roles of aTRNPV and aTRNSST neurons in propofol and isoflurane anesthesia. Electroencephalogram (EEG) recordings and behavioral tests were recorded and analyzed. Lastly, chemogenetic activation of the aTRNPV neurons was applied to confirm the function of the aTRN neurons in propofol and isoflurane anesthesia. c-Fos straining showed that both aTRNPV and aTRNSST neurons are activated during the LOC period of propofol and isoflurane anesthesia. Optogenetic activation of aTRNPV and aTRNSST neurons promoted isoflurane induction and delayed the recovery of consciousness (ROC) after propofol and isoflurane anesthesia, meanwhile chemogenetic activation of the aTRNPV neurons displayed the similar effects. Moreover, optogenetic and chemogenetic activation of the aTRN neurons resulted in the accumulated burst suppression ratio (BSR) during propofol and isoflurane GA, although they represented different effects on the power distribution of EEG frequency. Our findings reveal that the aTRN GABAergic neurons play a critical role in promoting the induction of propofol- and isoflurane-mediated GA.

Synapse-Specific Trapping of SNARE Machinery Proteins in the Anesthetized Drosophila Brain.

General anesthetics disrupt brain network dynamics through multiple pathways, in part through postsynaptic potentiation of inhibitory ion channels as well as presynaptic inhibition of neuroexocytosis. Common clinical general anesthetic drugs, such as propofol and isoflurane, have been shown to interact and interfere with core components of the exocytic release machinery to cause impaired neurotransmitter release. Recent studies however suggest that these drugs do not affect all synapse subtypes equally. We investigated the role of the presynaptic release machinery in multiple neurotransmitter systems under isoflurane general anesthesia in the adult female Drosophila brain using live-cell super-resolution microscopy and optogenetic readouts of exocytosis and neural excitability. We activated neurotransmitter-specific mushroom body output neurons and imaged presynaptic function under isoflurane anesthesia. We found that isoflurane impaired synaptic release and presynaptic protein dynamics in excitatory cholinergic synapses. In contrast, isoflurane had little to no effect on inhibitory GABAergic or glutamatergic synapses. These results present a distinct inhibitory mechanism for general anesthesia, whereby neuroexocytosis is selectively impaired at excitatory synapses, while inhibitory synapses remain functional. This suggests a presynaptic inhibitory mechanism that complements the other inhibitory effects of these drugs.

Esketamine accelerates emergence from isoflurane general anaesthesia by activating the paraventricular thalamus glutamatergic neurones in mice

BackgroundDelayed emergence from general anaesthesia poses a significant perioperative safety hazard. Subanaesthetic doses of ketamine not only deepen anaesthesia but also accelerate recovery from isoflurane anaesthesia; however, the mechanisms underlying this phenomenon remain elusive. Esketamine exhibits a more potent receptor affinity and fewer adverse effects than ketamine and exhibits shorter recovery times after brief periods of anaesthesia. As the paraventricular thalamus (PVT) plays a pivotal role in regulating wakefulness, we studied its role in the emergence process during combined esketamine and isoflurane anaesthesia. MethodsThe righting reflex and cortical electroencephalography were used as measures of consciousness in mice during isoflurane anaesthesia with coadministration of esketamine. The expression of c-Fos was used to determine neuronal activity changes in PVT neurones after esketamine administration. The effect of esketamine combined with isoflurane anaesthesia on PVT glutamatergic (PVTGlu) neuronal activity was monitored by fibre photometry, and chemogenetic technology was used to manipulate PVTGlu neuronal activity. ResultsA low dose of esketamine (5 mg kg−1) accelerated emergence from isoflurane general anaesthesia (474 [30] s vs 544 [39] s, P=0.001). Esketamine (5 mg kg−1) increased PVT c-Fos expression (508 [198] vs 258 [87], P=0.009) and enhanced the population activity of PVTGlu neurones (0.03 [1.7]% vs 6.9 [3.4]%, P=0.002) during isoflurane anaesthesia (1.9 [5.7]% vs –5.1 [5.3]%, P=0.016) and emergence (6.1 [6.2]% vs –1.1 [5.0]%, P=0.022). Chemogenetic suppression of PVTGlu neurones abolished the arousal-promoting effects of esketamine (459 [33] s vs 596 [33] s, P<0.001). ConclusionsOur results suggest that esketamine promotes recovery from isoflurane anaesthesia by activating PVTGlu neurones. This mechanism could explain the rapid arousability exhibited upon treatment with a low dose of esketamine.

Selective optogenetic modulation of the PBN terminals in the lateral hypothalamic area and basal forebrain regulates emergence from isoflurane anesthesia in mice

While the mechanism of general anesthesia has been extensively studied, the underlying neural circuitry has yet to be fully understood. The parabrachial nucleus (PBN) plays a crucial role in modulating wakefulness and promoting arousal from general anesthesia. However, the specific role of PBN projections in the process of general anesthesia remains unclear. In this study, we bilaterally injected AAV-associated viruses encoding excitatory or inhibitory optogenetic probes into the PBN and implanted optical fibers in the LH or BF area. After four weeks, we optogenetically activated or inhibited the PBN-LH and PBN-BF pathways under 1.5 vol% isoflurane. We calculated the time it took for anesthesia induction and emergence, simultaneously monitoring changes in the burst-suppression ratio using electroencephalogram recording. Our findings indicate that optogenetic activation of the PBN-LH and PBN-BF projections plays a significant role in promoting both cortical and behavioral emergence from isoflurane inhalation, without significantly affecting the induction time. Conversely, photoinhibition of these pathways prolonged the recovery time, with no notable difference observed during the induction phase.In summary, our results demonstrate that the PBN-LH and PBN-BF pathways are crucial for promoting arousal from isoflurane general anesthesia, but do not have a pronounced impact on the induction phase.

Intracardiac Induced Ventricular Fibrillation for the Euthanasia of Sheep.

Euthanasia is the humane termination of an animal's life and an important consideration for scientists, veterinarians, regulators, and others contemplating investigations involving animals. Techniques for euthanasia must induce the most rapid, painless, and distress-free death possible. This study investigated the effectiveness of direct current induction of ventricular fibrillation for the euthanasia of sheep after a primary study in which artifacts or chemical contamination from injectable euthanasia agents were undesirable. Female crossbred adult sheep (Ovis aries; n = 12) under deep isoflurane general anesthesia were instrumented with electrophysiology catheters to induce ventricular fibrillation for euthanasia. Data regarding invasive arterial blood pressure, expired airway gases, limb lead electrocardiograms, and pulse oximetry were collected and assessed just prior to, immediately after, and at 5, 10, 15, and 20min after energy delivery. In all animals, a single 10-s application of 9V of direct current to the right ventricular endocardium via the electrophysiology catheter induced persistent ventricular fibrillation. Arterial blood pressure (mean ± 1 SD) immediately after fibrillation induction was 22.9±4.5mmHg, with negligible difference between systolic and diastolic pressures. The lack of differential pressure continued through the end of the monitoring period. Arterial blood pressure reached an initial nadir at 1??0.5min after fibrillation induction, peaked (40.8±11.1mmHg) due to a vasoconstrictive reflex at 3min after induction, and returned to a static uniform pressure (20.4±17.8mmHg) with mildly increased variability due to reflexive diaphragmatic contractions at 10min after induction. The use of 9V direct current for the induction of ventricular fibrillation via an electrophysiology catheter is a reliable method of euthanasia in sheep.

Quiescence during burst suppression and postictal generalized EEG suppression are distinct patterns of activity

ObjectivePeriods of low-amplitude electroencephalographic (EEG) signal (quiescence) are present during both anesthetic-induced burst suppression (BS) and postictal generalized electroencephalographic suppression (PGES). PGES following generalized seizures induced by electroconvulsive therapy (ECT) has been previously linked to antidepressant response. The commonality of quiescence during both BS and PGES motivated trials to recapitulate the antidepressant effects of ECT using high doses of anesthetics. However, there have been no direct electrographic comparisons of these quiescent periods to address whether these are distinct entities. MethodsWe compared periods of EEG quiescence recorded from two human studies: BS induced in 29 healthy adult volunteers by isoflurane general anesthesia and PGES in 11 patients undergoing right unilateral ECT for treatment-resistant depression. An automated algorithm allowed detection of EEG quiescence based on a 10-microvolt amplitude threshold. Spatial, spectral, and temporal analyses compared quiescent epochs during BS and PGES. ResultsThe median (interquartile range) voltage for quiescent periods during PGES was greater than during BS (1.81 (0.22) microvolts vs 1.22 (0.33) microvolts, p < 0.001). Relative power was greater for quiescence during PGES than BS for the 1–4 Hz delta band (p < 0.001), at the expense of power in the theta (4–8 Hz, p < 0.001), beta (13–30 Hz, p = 0.04) and gamma (30–70 Hz, p = 0.006) frequency bands. Topographic analyses revealed that amplitude across the scalp was consistently higher for quiescent periods during PGES than BS, whose voltage was within the noise floor. ConclusionsQuiescent epochs during PGES and BS have distinct patterns of EEG signals across voltage, frequency, and spatial domains. SignificanceQuiescent epochs during PGES and BS, important neurophysiological markers for clinical outcomes, are shown to have distinct voltage and frequency characteristics.

Acipimox Induces the Hepatic Accumulation of Long‐Chain Diacylglycerides and Triglycerides in Severely Burned Sprague Dawley Rats

ObjectivePersistent lipolysis is a hallmark of severe burns, contributing to futile triglyceride cycling and the accumulation of lipid in ectopic tissues. It has been suggested that the administration of acipimox, a potent inhibitor of lipolysis, may blunt the hypermetabolic response to burns. However, what impact massive burns has on the accumulation of individual lipid species in the liver and how this is affected by acipimox treatment is unknown.HypothesisWe hypothesize that large burns results in the accumulation of lipotoxic species within the liver and that this can be prevented by administering acipimox.MethodsThirty‐two male Sprague Dawley rats were randomized to receive either a scald burn (~60% total body surface area) or sham procedure, performed under isoflurane general anesthesia. Afterwards, animals were further randomized to receive either acipimox (50 mg/kg/day) or vehicle (saline) by i.p. injection administered once a day for 7 days. On day 7, animals were euthanized and the liver snap frozen in liquid nitrogen. Liver lipids were extracted by using a chloroform:methanol (2:1) solution and diacylglycerol (DAG), triacylglycerol (TAG), free fatty acids (FFA) and cholesterol esters (CE) separated by thin‐layer chromatography. Afterwards, individual lipid classes were esterified to methyl esters, derivatized using heptane, and analyzed by gas chromatography (GC). The fatty acids C16:0, C18:0, cis/trans C18:1, cis 18:2, C20:0, C22:0, C24:0, and C22:6 were resolved by GC for each of the lipid classes examined.ResultsLiver weights were comparable between groups. Burn injury had no significant effect on the concentration of liver lipids compared to sham treated animals, irrespective of lipid class (P &gt; 0.05). In contrast, the administration of acipimox significantly increased liver C16:0 (2.1‐fold; P &lt; 0.05), trans C18:1 (2.5‐fold; P &lt; 0.05), and cis C18:2 (5.5‐fold; P &lt; 0.05) TAG content in burned animals, when compared to injured animals treated with vehicle. No effect of acipimox on liver lipids was observed in sham treated animals.ConclusionContrary to expectations, acipimox causes the accumulation of long‐chain TAGs in rat liver following massive burns, but this is not observed in response to burn injury alone. The ability of acipimox to cause unwanted hepatic metabolic side effects warrants further investigation before it is used clinically to treat massive burns.

The posterior dominant rhythm: an electroencephalographic biomarker for cognitive recovery after general anaesthesia

BackgroundThe posterior dominant rhythm (PDR) was the first oscillatory pattern noted in the EEG. Evoked by wakeful eyelid closure, these oscillations dissipate over seconds during loss of arousal. The peak frequency of the PDR maintains stability over years, suggesting utility as a state biomarker in the surveillance of acute cognitive impairments. This EEG signature has not been systematically investigated for tracking cognitive dysfunction after anaesthetic-induced loss of consciousness. MethodsThis substudy of Reconstructing Consciousness and Cognition (NCT01911195) investigated the PDR and cognitive function in 60 adult volunteers randomised to either 3 h of isoflurane general anaesthesia or resting wakefulness. Serial measurements of EEG power and cognitive task performance were assessed relative to pre-intervention baseline. Mixed-effects models allowed quantification of PDR and neurocognitive trajectories after return of responsiveness (ROR). ResultsIndividuals in the control group showed stability in the PDR peak frequency over several hours (median difference/inter-quartile range [IQR] of 0.02/0.20 Hz, P=0.39). After isoflurane general anaesthesia, the PDR peak frequency was initially reduced at ROR (median difference/IQR of 0.88/0.65 Hz, P<0.001). PDR peak frequency recovered at a rate of 0.20 Hz h−1. After ROR, the PDR peak frequency correlated with reaction time and accuracy on multiple cognitive tasks (P<0.001). ConclusionThe temporal trajectory of the PDR peak frequency could be a useful perioperative marker for tracking cognitive dysfunction on the order of hours after surgery, particularly for cognitive domains of working memory, visuomotor speed, and executive function. Clinical trial registrationNCT01911195.

Clinico-haematobiochemical Evaluation of Diaphragmatic Hernia and its Surgical Management in Cattle and Buffaloes- A Retrospective Study of 32 Cases

Background: Diaphragmatic hernia is an emerging threat in dairy animals due to accidental ingestion of potential foreign body via feed or fodder leads to traumatic reticulo pericarditis and net results into loss of milk production. Loss of milk production due to diaphragmatic hernia in dairy animals is worrying situation among the milkman and it needs to be addressed in early stage. Considering the livelihood of poor to marginal farmers on dairy animals, the present study aimed to evaluate the clinico-haematological changes and surgical management of diaphragmatic hernia in cattle and buffalo. Methods: The present retrospective study was carried in thirty two clinical cases of diaphragmatic hernia in cattle (17) and buffaloes (15) presented to teaching veterinary clinical complex from the rural area irrespective breeds, age and no. of lactation of animals. Result: The incidence was higher in recently parturited followed by advanced pregnant animals aged between 3.5-14 years (7.109±0.406) with duration of illness ranged between 4-35 days (16.563±1.627). All animals showed recurrent tympany, suspended rumination, constipation, neutrophilia, alkaline ruminal pH, lymphopenia and increased level of muscle enzymes and non-responsive to medicinal therapy. Plain radiography of thoraco-abdominal region showed break in continuity of diaphragmatic line and herniation of reticulum into thoracic cavity. All animals were subjected to surgical correction of diaphragmatic hernia under isoflurane general anaesthesia. Out of 32, 27 animals were recovered uneventfully and remaining five animals were succumbed during surgical repair of hernia due to cardiovascular failure. The present study concludes that, diaphragmatic hernia is common wasting disorders in dairy animals characterized by scanty faeces, recurrent tympany, neutrophilia, increased level of muscle enzymes due to chronic inflammatory changes and it can be treated successfully with herniorrhaphy under isoflurane general anaesthesia.

Sulforaphane improves cognitive dysfunction after surgery and anesthesia in mice: The role of Keap1-Nrf2 signaling

Anesthesia and surgery are likely causing cognitive dysfunction in patients, especially the elderly. However, the underlying pathogenic mechanisms largely remain unclear. Accumulating evidence suggest that signaling between Kelch-like erythroid cell-derived protein with CNC homology (ECH)-associated protein 1 (Keap1) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) plays an important role in the pathogenesis and treatment of brain dysfunction, while sulforaphane (SFN), a natural compound acting as an Nrf2 agonist, can improve brain function. In the present study, we used 9-month-old mice to perform tibial fracture surgery under isoflurane general anesthesia. Hierarchical cluster analysis of Morris water maze test (MWMT) analysis was performed to classify mice into post-operative cognitive dysfunction (POCD) versus non-POCD phenotypes. Expression levels of Keap1 and Nrf2 were significantly decreased in the medial prefrontal cortex (mPFC), hippocampus and liver, but not in the nucleus accumbens, muscle and gut of POCD mice compared to control and non-POCD mice. Interestingly, both pretreatment and posttreatment with SFN significantly improved the abnormal behaviors of mice in the MWMT, in parallel with the up-regulated levels of Keap1-Nrf2 signaling in the mPFC, hippocampus and liver. In conclusion, these results suggest that decreased Keap1-Nrf2 signaling in the mPFC, hippocampus and liver may contribute to the onset of POCD, and that SFN exerts facilitating effects on POCD symptoms by increasing Keap1-Nrf2 signaling.

Gene-Specific DNA Methylation Linked to Postoperative Cognitive Dysfunction in Apolipoprotein E3 and E4 Mice.

Geriatric surgical patients are at higher risk of developing postoperative neurocognitive disorders (NCD) than younger patients. The specific mechanisms underlying postoperative NCD remain unknown, but they have been linked to genetic risk factors, such as the presence of APOE4, compared to APOE3, and epigenetic modifications caused by exposure to anesthesia and surgery. To test the hypothesis that compared to E3 mice, E4 mice exhibit a more pronounced postoperative cognitive impairment associated with differential DNA methylation in brain regions linked to learning and memory. 16-month-old humanized apolipoprotein-E targeted replacement mice bearing E3 or E4 were subjected to surgery (laparotomy) under general isoflurane anesthesia or sham. Postoperative behavioral testing and genome-wide DNA methylation were performed. Exposure to surgery and anesthesia impaired cognition in aged E3, but not E4 mice, likely due to the already lower cognitive performance of E4 prior to surgery. Cognitive impairment in E3 mice was associated with hypermethylation of specific genes, including genes in the Ephrin pathway implicated in synaptic plasticity and learning in adults and has been linked to Alzheimer's disease. Other genes, such as the Scratch Family Transcriptional Repressor 2, were altered after surgery and anesthesia in both the E3 and E4 mice. Our findings suggest that the neurocognitive and behavioral effects of surgery and anesthesia depend on baseline neurocognitive status and are associated with APOE isoform-dependent epigenetic modifications of specific genes and pathways involved in memory and learning.

Modulation of Peripheral CD4+CD25+Foxp3+ Regulatory T Cells Ameliorates Surgical Stress-Induced Atherosclerotic Plaque Progression in ApoE-Deficient Mice.

Systemic inflammation associated with major surgery rapidly accelerates atherosclerotic plaque progression in mice. Regulatory T cells (Tregs) have emerged as important modulators of atherogenesis. In coronary artery disease patients, low frequency of Tregs constitutes an independent risk factor for cardiovascular complications after non-cardiac surgery. In this exploratory analysis, we investigate whether preoperative Treg levels affect surgery-induced atherosclerotic lesion destabilization in a murine model of perioperative stress. After 9 weeks of high-cholesterol diet, atherosclerotic apolipoprotein E-deficient mice with modulated Treg levels were subjected to a 30-minute surgical procedure consisting of general isoflurane anesthesia, laparotomy and moderate blood loss. Controls underwent general anesthesia only. Brachiocephalic arteries were harvested 3 days after the intervention for histomorphological analyses of atherosclerotic plaques. Tregs were depleted by a single dose of anti-CD25 monoclonal antibody (mAb) administered 6 days prior to the intervention. Expansion of Tregs was induced by daily injections of IL-2/anti-IL-2 complex (IL-2C) on three consecutive days starting 3 days before surgery. Isotype-matched antibodies and PBS served as controls. Antibody-mediated modulation was Treg-specific. IL-2C treatment resulted in an eight-fold elevation of peripheral CD4+CD25+Foxp3+ Tregs compared to mice administered with anti-CD25 mAb. In mice treated with PBS and anti-CD25 mAb, surgical stress response caused a significant increase of atherosclerotic plaque necrosis (PBS: p < 0.001; anti-CD25 mAb: p = 0.037). Preoperative Treg expansion abrogated perioperative necrotic core formation (p = 0.556) and significantly enhanced postoperative atherosclerotic plaque stability compared to PBS-treated mice (p = 0.036). Postoperative plaque volume (p = 0.960), stenosis (p = 0.693), lesional collagen (p = 0.258), as well as the relative macrophage (p = 0.625) and smooth muscle cell content (p = 0.178) remained largely unaffected by preoperative Treg levels. In atherosclerotic mice, therapeutic expansion of Tregs prior to major surgery mitigates rapid effects on perioperative stress-driven atherosclerotic plaque destabilization. Future studies will show, whether short-term interventions modulating perioperative inflammation qualify for prevention of cardiovascular events associated with major non-cardiac surgery.

WITHDRAWN: Mortality outcomes in avian patients undergoing isoflurane general anaesthesia in a veterinary referral and first opinion practice

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy .

Effect of basal forebrain somatostatin and parvalbumin neurons in propofol and isoflurane anesthesia.

AimsThe basal forebrain (BF) plays an essential role in wakefulness and cognition. Two subtypes of BF gamma‐aminobutyric acid (GABA) neurons, including somatostatin‐expressing (GABASOM) and parvalbumin‐positive (GABAParv) neurons, function differently in mediating the natural sleep–wake cycle. Since the loss of consciousness induced by general anesthesia and the natural sleep–wake cycle probably share similar mechanisms, it is important to clarify the accurate roles of these neurons in general anesthesia procedure.MethodsBased on two transgenic mouse lines expressing SOM‐IRES‐Cre and PV‐IRES‐Cre, we used a combination of genetic activation, inactivation, and chronic ablation approaches to further explore the behavioral and electroencephalography (EEG) roles of BFSOM and BFParv neurons in general anesthesia. After a single intravenous injection of propofol and the induction and recovery times of isoflurane anesthesia, the anesthesia time was compared. The changes in cortical EEG under different conditions were also compared.ResultsActivation of BF GABASOM neurons facilitates both the propofol and isoflurane anesthesia, manifesting as a longer anesthesia duration time with propofol anesthesia and a fast induction time and longer recovery time with isoflurane anesthesia. Moreover, BF GABASOM‐activated mice displayed a greater suppression of cortical electrical activity during anesthesia, showing an increase in δ power bands or a simultaneous decrease in high‐frequency power bands. However, only a limited and nuanced effect on propofol and isoflurane anesthesia was observed with the manipulated BF GABAParv neurons.ConclusionsOur results suggested that BF GABASOM neurons play a critical role in propofol and isoflurane general anesthesia, while BF GABAParv neurons appeared to have little effect.

Cautery Disbudding Iron Application Time and Brain Injury in Goat Kids: A Pilot Study.

Cautery disbudding is a painful procedure performed on goat kids to prevent horn growth that may result in brain injury. Thermal damage to the cerebral cortex of the brain and subsequent neurologic disease is a primary concern. Cautery iron application time may affect transmission of heat to the brain; however, research in this area is scarce. Therefore, the objective of this pilot study was to evaluate the effect of iron application time on brain injury of goat kids. A total of six buck and doe kids <9 days of age were obtained from a commercial dairy and transported to an Iowa State University research facility. Kids received a different randomly assigned application time (5, 10, 15, or 20s) on each horn bud. Kids were disbudded using an electric cautery iron (under isoflurane general anesthesia). After a 5-day observation period, the kids were euthanized, and magnetic resonance (MR) images were acquired to evaluate brain injury. Additionally, four of the six kids were presented for gross examination and two kids were selected for histopathologic examination. From the MR images, white matter edema was observed subjacent to four treated areas, representing application times of 5 s (one horn bud), 15 s (one horn bud), and 20 s (two horn buds). With the exception of the horn bud that received 5 s, which had white matter edema restricted to a single gyrus, the remaining three groups had a branching region of edema. No bone abnormalities were identified on any kids. Gross evidence of discoloration and hemorrhage on the cerebral hemispheres was observed on two horn buds that received 20 s, two horn buds that received 15 s, and one horn bud that received 10 s. Microscopic lesions consisting of leptomeningeal and cerebrocortical necrosis were observed in sections of brain from all groups. Lesions were most severe with 20 s. In conclusion, all application times used in this study resulted in some level of brain injury; however, using 15 s or more resulted in more severe and consistent brain injury. These results indicate that extended iron application time may increase the risk of brain injury in cautery disbudded kids.

Comorbidity-dependent changes in alpha and broadband electroencephalogram power during general anaesthesia for cardiac surgery

BackgroundAge and comorbidities are reported to induce neurobiological transformations in the brain. Whilst the influence of ageing on anaesthesia-induced electroencephalogram (EEG) changes has been investigated, the effect of comorbidities has not yet been explored. We hypothesised that certain diseases significantly affect frontal EEG alpha and broadband power in cardiac surgical patients. MethodsWe analysed the frontal EEGs of 589 patients undergoing isoflurane general anaesthesia from a prospective observational study. We used multi- and uni-variable regression to analyse the relationships between comorbidities and age as independent with peak and oscillatory alpha, and broadband power as dependent variables. A score of comorbidities and minimum alveolar concentration (MAC) was built to interrogate the combined effect of age and score on alpha and broadband power. ResultsAt the univariable level, many comorbidities were associated with lower EEG alpha or broadband power. Multivariable regression indicated the independent association of numerous comorbidities and MAC with peak alpha (R2=0.19) and broadband power (R2=0.31). The association with peak alpha power is markedly reduced when the underlying broadband effect is subtracted (R2=0.09). Broadband measures themselves are more strongly correlated with comorbidities and MAC (R2=0.31) than age (R2=0.15). ConclusionsComorbidities and age are independently associated with decreasing frontal EEG alpha and broadband power during general anaesthesia. For alpha power, the association is highly dependent on the underlying broadband effect. These findings might have significant clinical consequences for automated computation for depth of anaesthesia in comorbid patients, because misclassification might pose the risk of under- or over-dosing of anaesthetics. Clinical trial registrationNCT02976584.

Bubble bilevel ventilation facilitates gas exchange in anesthetized rabbits.

BackgroundBubble continuous positive airway pressure is an established therapy for infants in respiratory distress. In resource-limited settings, few treatment options exist for infants requiring further respiratory support. A bubble bilevel device has been developed to provide nonelectric, time-cycled, pressure-limited respiratory support. We compared the efficacy of bubble bilevel ventilation with conventional mechanical ventilation in sedated rabbits.MethodsSix adult rabbits under inhaled isoflurane general anesthesia were ventilated by alternating intervals of conventional and bubble bilevel ventilation for three 10−15-min periods. During each period, interval arterial blood gas (ABG) measurements were obtained after at least 10 min on the respective mode of ventilation.ResultsThe bubble bilevel system was able to deliver the following pressures: 20/7, 15/5, 12/5, 8/5 cm H2O. The estimated differences in arterial blood gas values on bubble bilevel vs. ventilator were as follows (normalized values): pH 7.41 vs. 7.40, pCO2 37.7 vs. 40, pO2 97.6 vs. 80. In addition, the bubble bilevel ventilation delivered consistent pressure waveforms without interruption for over 60 min on two rabbits.ConclusionThis study demonstrates promising in vivo results on the efficacy of a novel bubble bilevel device, which may prove useful for infants in respiratory distress.Impact Given the lack of personnel, funds or infrastructure to provide neonatal mechanical ventilation in resource-limited settings, additional low-cost, low-tech treatments are necessary to save infant lives.Bubble bilevel ventilation reliably delivers two levels of airway pressure to anesthetized rabbits resulting in normalization of blood gases comparable to those achieved on a traditional ventilator.If proven effective, simple technologies like this device have the potential to significantly impact neonatal mortality due to respiratory distress globally.

Haemodynamic changes and emergence delirium in children undergoing isoflurane general anaesthesia for dental treatments: effect of propofol administration

ObjectiveTo evaluate the effects of administration of 1 mg·kg−1 propofol before the end of surgery on the haemodynamic values and incidence of emergence delirium in paediatric dental patients retrospectively. MethodsNinety-seven children aged between 2 and 12 who were treated under general anaesthesia in Yeditepe University Faculty of Dentistry were included. Midazolam for premedication and intravenous propofol for induction and isoflurane for maintenance of anaesthesia were used. One mg·kg−1 propofol was administered before extubation and 15 min before the end of surgery. The monitorized haemodynamic values including heart rate, oxygen saturation in periferic circulation, CO2 in expirium and body temperature were collected from patient files. The level of emergence delirium was measured using the Pediatric Anaesthesia Emergence Delirium Scale. ResultsThirty-nine girls and fifty-eight boys (5.21 ± 2.32) were investigated. A statistically significant increase was found in the mean heart rate during induction and end of intubation. Expired CO2 significantly increased after the end of intubation and decreased at the end of anaesthesia. According to the Pediatric Anaesthesia Emergence Delirium Scale none of the patients were scored as emergence delirium and 52,78% of the children were scored as 0. ConclusionsWhen administration of single dose of propofol is used for the prevention of Emergence Delirium, constant monitoring of expired CO2 values during and after the end of intubation is essential. It can be suggested that administration of a single dose of 1 mg·kg−1 propofol prevents emergence delirium in paediatric dental patients; nevertheless this finding should be confirmed with prospective clinical trials.

Comparison of the Effects of Isoflurane and Sevoflurane General Anaesthesia after Induction by Propofol on Clinical and Physiological Measurements in Calves

Background: In veterinary surgical operations for cats and dogs, inhalation anaesthesia is known to be a good option for general anaesthesia in long operations or emergency cases. Studies have revealed that during inhalation anaesthesia, the heart and respiratory functions of the animals are more stable compared to injectable anaesthesia. However, there are few studies performed with the use of inhalation anaesthesia in ruminants. In this research, the goal is to evaluate the effects of isoflurane and sevoflurane after induction with propofol in calves based on clinical and physiological parameters and to find a more reliable strategy for general anaesthesia in ruminants.Materials, Methods &amp; Results: The research was carried out on 30 calves, from new-born up to 3-months-old, undergoing surgery operation. Each group consisted of 15 animals that were divided as isoflurane and sevoflurane. For premedication, atropine was administered at a dose of 0.04 mg/kgvia subcutaneous injection in calves. For induction, 15 min after atropine application, propofol was given at 5-6 mg/kgvia intravenous infusion. Then, endotracheal intubation was performed and inhalation anaesthesia began at 5 min after induction. In the isoflurane group, the onset of anaesthesia concentration was set to 3-5% and the maintenance was set to a concentration of 1.5-3%. In the sevoflurane group, the onset of anaesthesia concentration was set to 5-7% and the maintenance was set to a concentration of 2.5-4%. To monitor the calves, the heart rate (HR), the pulse rate (PR), the systolic blood pressure (SBP), diastolic blood pressure (DBP), the respiratory rate (RR), the rectal temperature (RT) and the electrocardiogram (ECG) measurements were recorded before anaesthesia, the premedication, the induction periods, at 5, 15, 30, 45, 60, and 75 min after the onset of inhalation anaesthesia during the operation period. Blood samples were taken before anaesthesia, premedication, induction periods, at 30 and 75 min during the operation and the red blood cell (RBC) count, white blood cell (WBC) count, the amount of haemoglobin (HGB), the haematocrit concentration (HCT), and the platelet (PLT) count were evaluated. Based on the findings, isoflurane and sevoflurane suppressed the cardiovascular system minimally. Both anaesthetic agents caused decreases that did not exceed the physiological limits compared to the measurements taken before the initiation of anaesthesia. Although no significant differences were detected between the groups (P &gt; 0.05) at clinical parameters, the RT differences were regarded as statistically significant according to the measurements that were taken before anaesthesia at all measurement times (P &lt; 0.05). In both groups, the changes that occurred in the P wave, the PR interval, and in the QRS, R and T waves remained within the reference values given in the literature. Both anaesthetic agents have similar effects on the ECG. The dramatic no changes throughout anaesthesia in terms of the amount of HGB and HCT, the RBC, the WBC, and the PLT were not statistically significant, which may be associated with good tissue perfusion.Discussion: Since no serious complications occurred with either anaesthetic option, we have concluded that isoflurane and sevoflurane have similar effects on the cardiopulmonary systems of calves. In addition, the effects of propofol, which is used for induction, have been evaluated and observed and this drug is an effective and reliable option to initiate inhalation anaesthesia. The research on the use of this anaesthetic in calves is limited and most of the existing studies investigated its combination with injectable anaesthetics. As a result, in this research, we concluded that isoflurane and sevoflurane induce similar physiological measurement results, blood parameters, and ECG results and that both anaesthetics cause minimal complications.