Isoflurane Gas Research Articles

Expanding the invertebrate medicine toolbox: evaluation of opisthosoma tonometry as a novel diagnostic tool for arachnids.

The objective of this study was to analyze the use of rebound tonometry, as a noninvasive diagnostic tool, in arachnids. 5 juvenile (yearling) female and 1 juvenile male curlyhair tarantulas (Tliltocatl albopilosus, previously Brachypelma albopilosum) were used to track estimated ventral opisthosoma pressures over a 9-month period of time. Younger, growing animals were selected as they are more likely than adults to go through multiple molts throughout the 9 months of the study length. An iCare TONOVET TV01 rebound tonometer was used to measure the estimated ventral opisthosoma pressures of the spiders. Measurements were obtained from the ventral opisthosoma, 1 of the thinnest areas of exocuticle throughout the body. Readings were obtained once per week from the ventral opisthosoma for the first 2 months, then once every 2 weeks for 1 month, then back to once per week for the remainder of the study. Additional measurements were obtained following each ecdysis, after a 2% body weight sampling of hemolymph, and at the end of the study to evaluate readings in response to induction of general anesthesia with 5% isoflurane gas and oxygen flow at 2 L/min for 10 minutes. The average of all estimated ventral opisthosoma pressure when spiders were not in molt was 26.19 mm Hg (SD, 3.54), with a statistically significant decrease postmolt to an average of 15.31 mm Hg (SD, 3.81), followed by a gradual increase back to premolt pressures over a 3-week period with an average of 22 days (SD, 1.93). Estimated ventral opisthosoma pressures decreased post hemolymph removal. There is not sufficient evidence that estimated ventral opisthosoma pressures changed over time following the anesthesia. This study demonstrates that tonometry can be used to generally assess the estimated ventral opisthosoma pressure, which could correlate with where a spider is in an ecdysis cycle.

Establishing a Mouse Model of Surgical Vocal Fold Injury.

Animal models of vocal fold (VF) surgical injury and scar formation provide insight into the wound healing process. The purpose of this study was to establish an alternative model of surgical injury to the mouse VF using materials commonly available in most research laboratories or for purchase and to investigate wound healing of the epithelium (EP) and lamina propria (LP). Mice were anesthetized by isoflurane gas delivery and positioned on a platform so that the larynx could be observed using a laryngoscope and dissection microscope. Unilateral VF injury was created using a wire brush. Mice were euthanized and the larynx evaluated 1-, 3-, 5-, 7-, 14-, and 28-days following injury. Histological and immunofluorescent analysis was used to evaluate thickness of the EP, LP area, proliferative (Ki67+) and basal cells (p63+) in the EP, and collagen III content in the LP. The depth of injury reached the superficial thyroarytenoid muscle on Day 1. The thickness of the EP of the injured VF was increased on Days 3 and 5, and the LP area was increased on Days 3, 5, and 7 as compared with the uninjured VF. Ki67+ and p63+ cells were increased on Day 3 and collagen III content was increased on Days 5 and 28 as compared with the uninjured VF. We successfully established an alternative method of creating unilateral VF injury in the mouse. This method will be useful for future research regarding VF surgical injury and wound healing. N/A Laryngoscope, 2024.

#598 Successful application of allo-hemodialysis in a porcine model of embolization-induced acute kidney injury

Abstract Background and Aims Annually, millions of kidney patients, primarily in low- and low-middle income nations, die prematurely due to the lack of affordable kidney replacement therapy. We propose a novel, low-cost alternative dialysis modality called allo-hemodialysis (alloHD), where blood of a patient with kidney failure flows counter-current to the blood of a healthy subject (“buddy”) through the dialyzer [1]. Uremic solutes and excess fluid are then excreted by the buddy's healthy kidneys. We have already demonstrated the technical feasibility of alloHD in pigs with acute kidney injury (AKI) induced by renal artery ligation [2]. In this study, we explored alloHD in a less invasive porcine model of AKI induced by renal artery embolization. Method The protocol was approved by the Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA), New Delhi, India. We studied two female Yorkshire pigs (weight 80-90 kg) with central venous catheter as vascular access. AKI was induced by embolization of both kidneys by transcatheter deployment of Contour™ Poly Vinyl Alcohol particles (Boston Scientific, Marlborough, MA, USA). The AKI pig and the buddy pig were connected to the dialysate and blood compartments, respectively, of a Nipro Cellentia 17H dialyzer. The AKI pig was then dialyzed for 4 hours against the healthy buddy pig. During alloHD, both pigs were anticoagulated with heparin (5,000 IU/h) and the buddy pig was sedated with 1-2% isoflurane gas. Blood samples were collected before, during, and after alloHD for measurements of blood urea nitrogen (BUN) and creatinine. Results We performed nine alternate day alloHD sessions with the same pair of pigs. During alloHD, BUN and Creatinine levels declined in the AKI pig (Fig. 1) and increased—as expected—transiently above baseline in the buddy pig and then trended towards baseline post-dialysis (Fig. 1). We found no indication of hemolysis or coagulation of the extracorporeal circuit in any of the nine alloHD sessions. The animals were sacrificed after the 9th session. Conclusion We demonstrated the feasibility of alloHD in a porcine embolization AKI model. This study corroborates and complements our previous experience with alloHD in a porcine model of AKI induced by renal artery ligation. Given these promising results, we are investigating the potential for advancing to a clinical trial.

The Unique Management of Accidental Intra-Arterial Injection of Propofol in a Patient with Acute Subdural Hemorrhage: A Case Report

Propofol is a commonly used medication for sedation during surgery; however, it must be used with precaution in neurologic patients because of the subsequent adverse effects of cardiovascular and neurologic.
 An 83-year-old male patient with acute subdural hemorrhage was referred with a two-year history of falling and a recent occurrence of imbalance; the patient underwent urgent surgery under general anesthesia, using 100 µg fentanyl for premedication, 50 mg Propofol for induction, and Isoflurane gas and fentanyl drip for maintenance. During transmission of the patient for postsurgical computed tomography, two ccs Propofol 1% were mistakenly injected into the patient's radial artery and managed appropriately by the master. Following this management, the patient represented no alteration in his vital signs and was discharged in a favorable condition. Here, we report how this case could be managed successfully.
 Robust data regarding the complications of accidental administration of Propofol through an artery are lacking, and the presented results remain controversial. The authors have herby drawn attention to the unique management of an accidental intra-arterial injection of Propofol. Further studies are warranted to establish definite conclusions.

MODELING AND CONTROL OF ANAESTHETICS DURING POST SURGICAL TREATMENT

The major constraint in automatic control of anaesthesia is patient’s variability based on drug tolerance. A controller has to be designed in such way that it is robust to the actual patient’s response even if the controller is designed based on a nominal patient model. Anaesthetic agent used in this study is isoflurane gas and the controlled delivery of anaesthetic agent has to be given with utmost care of great accuracy because the agents used here have narrow therapeutic uses. The importance of the robustness of the controller to be designed is that it must provide a sufficient and controlled administration of drugs to avoid the situations of under and over dosing of patients. The hemodynamic parameters that are to be measured during drug administration is Mean Arterial Pressure (MAP) and heart rate (HR), whereas another parameter to be measured during anaesthesia delivery is measure of unconsciousness of the patient called asBi-spectral Index (BIS). In this study, the anaesthesia control system is modeled and controller design is made for patient undergoing Intensive Care Treatment (ICU) after valve replacement surgery. The background analysis is made by observing the realtimeparameters such as BIS, MAP, and HR of patient undergone valve replacement surgery.

Action of the general anaesthetic isoflurane reveals coupling between viscoelasticity and electrophysiological activity in individual neurons

General anaesthetics are widely used for their analgesic, immobilising, and hypnotic effects. The mechanisms underlying these effects remain unclear, but likely arise from alterations to cell microstructure, and potentially mechanics. Here we investigate this hypothesis using a custom experimental setup combining calcium imaging and nanoindentation to quantify the firing activity and mechanical properties of dorsal root ganglion-derived neurons exposed to a clinical concentration of 1% isoflurane gas, a halogenated ether commonly used in general anaesthesia. We found that cell viscoelasticity and functional activity are simultaneously and dynamically altered by isoflurane at different stages of exposure. Particularly, cell firing count correlated linearly with the neuronal loss tangent, the ratio of mechanical energy dissipation and storage by the cell. Our results demonstrate that anaesthetics affect cells as a whole, reconciling seemingly contradictory theories of how anaesthetics operate, and highlight the importance of considering cell mechanics in neuronal functions, anaesthesia, and clinical neuroscience in general.

(006) Methamphetamine-Induced Vaginal Lubrication

Abstract Introduction Vaginal dryness is a frequent complaint, especially in post-menopausal women. The physiology underlying the production of vaginal lubrication in response to arousing stimuli is established; however, no current pharmacological agents successfully target mechanisms within this physiology. Previous research from our lab has demonstrated that female methamphetamine (meth) users experience the immediate production of excessive vaginal lubrication, accompanied by a warmth or flushing sensation spreading from the chest areas to the pelvic region, when using the drug intravenously (IV). The physiological source of this previously undescribed effect of meth could present a potential mechanism to enhance a woman’s natural production of vaginal lubrication, providing a potentially life-changing option to patients experiencing vaginal dryness. Objectives The purpose of the current study was to determine if vaginal lubrication induced by IV meth use reported in a previous study from our lab occurs in rats, and if this effect is dose-dependent. This study also sought to begin to uncover the mechanism behind this phenomenon. Methods Adult female Wistar rats (n=8) were implanted with chronic indwelling jugular catheters and allowed at least one week to recover from surgery. Rats anesthetized with isoflurane gas were intravenously infused with one of seven doses of meth ranging from 0.015-0.96 mg/kg meth or saline IV via the implanted catheter. Pre-weighed cotton-tipped swabs inserted into the vaginal canal collected fluid secreted following drug administration. The change in weight of the swab was taken as the weight of fluid produced. Consequent studies examined several signaling molecules in plasma known to have an influence on vaginal lubrication, including the steroid hormones estradiol, progesterone and testosterone, as well as the gaseous vasodilator nitric oxide. These molecules were measured at time points up to 60 minutes after meth administration. Results As hypothesized, meth increased vaginal lubrication in a dose-dependent manner. Doses of 0.06 and 0.24 mg/kg of meth induced significant increases in vaginal lubrication compared to saline. Further, compared to pre-meth levels, significant increases in estradiol were seen at two and 15 minutes after meth administration. Significant increases in progesterone, testosterone and nitric oxide were seen ten minutes after meth administration. Conclusions This study has far-reaching implications since the majority of women will experience vaginal dryness at least once, if not recurrently. The underlying mechanism of meth-induced vaginal lubrication, when elucidated, may provide a pharmacological target in treating not only meth use disorder, but also the millions of women suffering from vaginal dryness. Disclosure No.

Exposure to anesthetic gases in the operating rooms and assessment of non-carcinogenic risk among health care workers

Health care workers employed operating room in hospital and health centers are unavoidably exposed to inhaling toxic gases, including isoflurane and sevoflurane. Chronic contact with these gases increases the risk of spontaneous abortion, congenital anomalies and cancers. Risk assessment is an important tool in predicting the possible risk to personnel's health. Therefore, this study was conducted with the aim of determining the concentration of isoflurane and sevoflurane gas in the air of the operating room and estimating the non-carcinogenic risk caused by them. In this descriptive-cross-sectional study, according to the occupational method (OSHA 103), 23 samples (isoflurane and sevoflurane) were collected in the air of operating rooms of four selected hospitals in Ahvaz city by using SKC sampling pumps and sorbent tube (Anasorb 747). The samples were determined by used to gas chromatography with a flame ionization detector (GC/FID). Statistical analysis, including the Kruskal-Wallis test, was used to compare the average concentration of anesthetic gases, and the one-sample t-test was used to compare the average with the standard level. In all analyses, the significance level was 0.05, which was performed by SPSS version 22 software. Result of this study showed that the average concentration of isoflurane in private and general hospitals were 23.636 and 17.575 ppm, respectively. Also, the average level of sevoflurane were 1.58 and 7.804 ppm. According to the results the mean amount of anesthetic gases was within the range recommended by Iran's Occupational and Environmental Health Center and the permissible threshold limit provided by ACGIH. In addition, non-cancer risks from occupational exposure to isoflurane and sevoflurane in selected private and general hospitals were acceptable (HQ < 1). Although the results show that overall occupational exposure to anesthetic gases is less than acceptable but long-term exposure to anesthetic gases may endanger the health of operating room staffs. Therefore, it is recommended to implement some technical controls, including regular inspection of ventilation systems, the use of advanced ventilation systems with high cleaning power, continuous control of anesthesia devices in terms of leakage, and periodic training of related staff.

(081) Comparing the Contributions of Nitric Oxide and Estrogen to Methamphetamine-Induced Alterations of Vaginal Blood Flow in Rats

Abstract Introduction Vaginal dryness is a frequent complaint, especially in post-menopausal women. The physiology underlying the production of vaginal lubrication in response to arousing stimuli is established; however, no current pharmacological agents successfully target mechanisms utilizing this physiology. Previous research from our lab has demonstrated that female methamphetamine (meth) users experience the production of excessive vaginal lubrication immediately following an intravenous injection of methamphetamine, and we have recapitulated this in an anesthetized rodent model. We have also found that this vaginal lubrication, as well as vaginal blood flow increased by meth, are heavily nitric oxide dependent. Objective The purpose of the current study is to determine if increased vaginal blood flow correlates with increased vaginal lubrication in response to meth, and to determine if alterations in this blood flow are dependent upon nitric oxide, estrogen, or both. Methods Adult female Wistar rats were implanted with chronic indwelling jugular catheters and allowed at least one week to recover from surgery. Rats anesthetized with isoflurane gas were intravenously infused with meth or saline via the implanted catheter. Vaginal blood flow, measured using a Periflux System 5000 and a small laser probe inserted 5-10 mm into the vaginal canal, was continuously recorded before and for at least twenty minutes following drug administration. After establishing meth-induced alterations in vaginal blood flow, rats were pre-treated with L-NG-Nitro arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor or fulvestrant, an estrogen receptor antagonist, followed by meth administration using the same procedure for measuring blood flow to determine the contribution of nitric oxide and estrogen. Results Meth immediately increases vaginal blood flow, followed by a decrease in perfusion, which is characteristic of a drug that induces such profound sympathetic activation. L-NAME reduced meth-induced increases in vaginal blood flow, and we predict that fulvestrant will be less effective. Conclusions Nitric oxide and estrogen are molecules critical to the production of vaginal lubrication. Nitric oxide, important for the vasodilation cascade leading to the production of vaginal transudate, contributes to meth-induced increases in vaginal blood flow and vaginal lubrication. Estrogen signaling likely contributes to meth-induced increases in vaginal blood flow, and thus, vaginal lubrication, but not as substantially as nitric oxide, making nitric oxide a better potential target for those suffering from vaginal dryness. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Embera NeuroTherapeutics &amp; JanOne, both affiliations unrelated to current research

Potassium penicillin and gentamicin pharmacokinetics in healthy conscious and anesthetized horses.

To determine the effects of general anesthesia on the safety and efficacy of co-administered potassium penicillin G (PEN) and gentamicin (GENT) in horses. Nonrandomized crossover. Six adult, Thoroughbred horses. Horses were administered PEN (22 000 IU/kg IV) and GENT (6.6 mg/kg IV). Plasma samples were collected over a 6 h period and synovial fluid was collected at 30 min and 6 h respectively. Drug administration and sample collection protocols were repeated after at least a 48 hour washout period and induction of anesthesia using xylazine/ketamine and maintenance with isoflurane gas. Drug concentrations were determined using ultrapressure liquid chromatography with mass spectrometry. A 2-compartment model was used to determine pharmacokinetics and differences were determined between conscious and anesthetized horses using paired t-tests (significance P< .05). Potassium penicillin g and GENT had higher minimum plasma concentrations (PEN 0.44 vs. 0.11 μg/mL, P= .002; GENT 3.0 vs. 1.9 μg/mL, P= .009), longer half lives (PEN 71 vs. 59 min, P= .018; GENT 149 vs. 109 min, P= .038), and slower clearances (PEN 3.41 vs. 5.1 mL/kg/min, P= .005; GENT 1.18 vs. 1.48 mL/kg/min, P= .028) in anesthetized horses vs. conscious horses. The PEN concentrations remained above the breakpoint minimum inhibitory concentration (MIC, 0.5 μg/mL) for 332 min in anesthetized vs. 199 min in conscious horses. The GENT concentrations reached 10 times higher than the breakpoint MIC (2 μg/mL) in all horses and were maintained for 58 vs. 59 min in anesthetized and conscious states, respectively. Synovial fluid concentrations were higher in conscious horses vs. anesthetized horses at 30 min for PEN (7.0 vs. 0.93 μg/mL, P< .001) and 30 (5.3 μg/mL vs. 0.79 μg/mL, P< .001) and 360 min (3.4 vs. 1.82 μg/mL, P < .003) for GENT. General anesthesia resulted in lower intrasynovial concentrations and delayed clearance of PEN/GENT in horses. Redosing healthy anesthetized horses with PEN prior to 4-5 h is not necessary. When administered to anesthetized horses, intravenous PEN/GENT may not reach adequate intrasynovial concentrations to treat or prevent common pathogens. The doses or dosing intervals of antimicrobials administered to horses undergoing anesthesia may need to be adjusted to ensure maintenance of safe and effective plasma concentrations.

Methamphetamine-Induced Alterations of Vaginal Blood Flow in Rats

ABSTRACT Introduction Those suffering with vaginal dryness, whether experienced once or chronically, frequently experience painful and unpleasurable sexual experiences and diminished self-esteem as a result. Although the physiology of vaginal transudate production is long established, no pharmacological treatment other than estrogen has shown promise in attenuating vaginal dryness. Previously, our lab has shown that methamphetamine (meth) induced vaginal lubrication in adult women and anesthetized rats. The production of these vaginal secretions was shown to be dose-, as well as nitric oxide-dependent. As the secretion of vaginal lubrication is immensely dependent on local hemodynamics and the resulting increased blood flow to the genital tissues, determining meth-induced alterations in blood flow to these tissues is paramount. Objective The purpose of the current study is to determine if increased vaginal blood flow correlates with increased vaginal lubrication in response to meth, and to determine if alterations in this blood flow are nitric oxide-dependent. Methods Adult female Wistar rats were implanted with chronic indwelling jugular catheters and allowed at least one week to recover from surgery. Rats anesthetized with isoflurane gas were intravenously infused with meth (0.06-0.96 mg/kg) or saline via the implanted catheter. Vaginal blood flow, measured using a Periflux System 5000 and a small laser probe inserted 5-10 mm into the vaginal canal, was continuously recorded before and for at least twenty minutes following drug administration. After establishing meth-induced alterations in vaginal blood flow, pre-treatment with L-NG-Nitro arginine methyl ester (L-NAME), a non-specific nitric oxide synthase inhibitor, followed by meth administration following the same procedure for measuring blood flow allowed us to determine the contribution of nitric oxide to the observed changes in blood flow. Results Preliminary findings show that an IV infusion of meth induces an immediate increase in vaginal blood flow, followed by decreased blood flow due to vasoconstriction via increased sympathetic tone. We anticipate inhibition of nitric oxide production will reduce the increase in blood flow immediately after meth administration since this decreased vaginal lubrication in response to the same treatment. Conclusions These findings provide insight into the meth-induced vaginal lubrication we have previously reported, and that meth, whose sympathomimetic action traditionally induces vasoconstriction, produces increased blood flow in vaginal tissues, which is likely the driving force for the increased transudate produced. This advancement is critical for uncovering a mechanism that may serve as the optimal pharmacological target to treat vaginal dryness. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Embera NeuroTherapeutics &amp; JanOne

Research Handling Effects on Stress Hormones, Blood Parameters, and Heart Rate in Juvenile Northern Elephant Seals (Mirounga angustirostris)

Wildlife researchers must balance the need to safely capture and handle their study animals while simultaneously ensuring study results are not confounded by stress artifacts caused by handling. To determine the physiological effects of research activities including chemical immobilization, transport, instrumentation with biologgers, and overnight holding on a model marine mammal species, we collected hormone, blood parameter, and heart rate data from 19 juvenile northern elephant seals (Mirounga angustirostris) throughout a translocation experiment. Blood samples were collected during the initial capture (baseline), the instrumentation procedure conducted under isoflurane gas anesthesia, the post‐procedure recovery period, and the recapture (2‐10 days post‐release). Continuous heart rate data was collected using electrocardiogram biologgers during the procedure, recovery, transport, and release. Serum cortisol levels increased from 6.6 ± 5.3 μg/dL at capture to a maximum of 29.2 ± 23.7 μg/dL during recovery. Similarly, serum aldosterone increased from baseline levels of 69.7 ± 63.1 pg/mL to 217.8 ± 101.2 pg/mL during the procedure. Cortisol was positively associated with aldosterone, which supports growing evidence that aldosterone is a component of the acute stress response in marine mammals. Blood glucose and hematocrit both varied throughout the experiment, while there were no significant changes in β‐hydroxybutyrate blood ketones or erythrocyte sedimentation rate. Seals exhibited bradycardia (mean heart rate = 49.7 ± 3.7 bpm) while anesthetized, followed by a gradual increase in mean heart rate during the recovery period to 73.5 ± 7.9 bpm. Despite these short‐term changes, by the time seals were recaptured after several days at sea, all hormonal and hematological parameters had returned to baseline levels and 95% of study animals were resighted in the wild up to two years post‐translocation. Together these findings suggest that while northern elephant seals exhibit mild physiological stress responses to capture and handling activities, they recover rapidly and show no long‐term deleterious effects, making them a robust species for ecological and physiological research.

Methamphetamine-Induced Vaginal Lubrication & Associated Hormonal Changes

ABSTRACT Introduction Vaginal dryness is an issue that affects millions of women, creating a situation that often leads to painful sexual experiences and diminished pleasure and self-esteem. Though the physiology of vaginal lubrication in response to sexually arousing stimuli is established, no treatment, other than topical lubricants, is available for women suffering from vaginal dryness. Previous research from our lab reported that female methamphetamine (meth) users experience immediate and noticeable vaginal lubrication when they inject the drug intravenously (IV). A warming or flushing sensation spreading from the chest area down into the pelvic region accompanied this lubrication. Understanding the mechanisms mediating this previously undescribed phenomenon may reveal a potential target for future pharmaceutical development to enhance a woman's natural levels of vaginal lubrication. We have reported that injections of meth also increase vaginal lubrication in rats in a dose-dependent manner. Plasma levels of several signaling molecules known to influence vaginal lubrication, including the steroid hormones estradiol, progesterone, and testosterone, as well as the gaseous vasodilator nitric oxide, increase at specific time points following IV meth in female rats. Accordingly, we were able to decrease the amount of vaginal fluid produced by pre-treating the animals with the nitric oxide synthase inhibitor, L-NAME, prior to meth. Objective The present work expands the aforementioned findings by measuring plasma levels of vasoactive intestinal polypeptide (VIP), an established mediator of female sexual arousal, and corticosterone, a steroid hormone implicated in drug addiction, after IV injections of meth. We also determined the involvement of estradiol in meth-induced vaginal lubrication using an estrogen receptor antagonist. Methods We implanted adult female Wistar rats with chronic indwelling jugular catheters and allowed them at least one week to recover from surgery. We pre-treated the rats with fulvestrant, an estrogen receptor antagonist, and then anesthetized them with isoflurane gas before injecting them intravenously with meth via the implanted catheter. A pre-weighed cotton-tipped swab, inserted into the vaginal canal, collected fluid secreted following the administration of meth. The change in the weight of the swab before and after meth indicated the amount of fluid produced. In a separate group of rats, we used the jugular catheter to remove blood at various time points (1-60 min) following the meth injections to measure plasma levels of VIP and corticosterone. Results Although we have not yet completed these experiments, we hypothesize that the inhibition of estrogen receptors will reduce meth-induced vaginal lubrication similar to the reduction produced by L-NAME. Further, we predict that both VIP and corticosterone levels will increase between 5 and 20 min after the injections of meth, similarly to the other signaling molecules we measured previously. Conclusions These findings have far-reaching and potentially life-changing implications, as the majority of women will experience vaginal dryness a least once in their lifetimes, if not chronically. The underlying mechanisms of meth-induced vaginal lubrication may provide the necessary pharmacological target to treat vaginal dryness. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Goeders is on the Scientific Advisory Boards for Embera NeuroTherapeutics and JanOne; however, the work of these companies is unrelated to the submitted abstract.

Anesthesia Depth Measurement with Bispectral Index Monitoring during Minor Surgery among Children With and Without Cerebral Palsy

Introduction: Unfortunately, few studies have been performed on the pharmacodynamic effects of anesthesia in children suffering cerebral palsy(CP).Patients were candidates for surgeryfor various reasons. Due to the lower need for anesthesiain these children, side effects of various anesthetic agents, adverse drug reactions, delayed awareness and higher costs can be prevented in these children. The present study aims to evaluate and compare the depth of anesthesia in minor surgeries using Bispectral Index (BSI) in children sufferingCP. Materials and Methods: This cohort study was performed on 64 children aged two to ten years in two groups with and without cerebral palsy inMofid Hospital, Tehran, Iran in 2020. BIS index, mean arterial blood pressure and heart rate were measured before and after anesthesia induction, every ten minutes during operation, after extubation and when being able to respond to verbal stimulation. Results: This studyexamined 64 patients equally divided into two study groups “with and without cerebral palsy”. The mean BIS level in children suffering CP was lower than children without cerebral palsy. The dosage of isoflurane gas used for anesthesia in CPpatientswas meaningfully lower than itsdosage in children without cerebral palsy. Conclusion: Monitoring of anesthesia in this study, showed that use of BIS could reduce the use of anesthetic agents and related side effects to provide the appropriate depth of anesthesia.

COMPARISON OF ISOFLURANE GAS VERSUS A GUAIFENESIN, KETAMINE, AND MEDETOMIDINE CONSTANT-RATE INFUSION FOR MAINTENANCE ANESTHESIA IN AMERICAN BLACK BEARS (URSUS AMERICANUS).

Published anesthetic protocols for captive and free-ranging bears are limited to injectable inductions with maintenance via inhalants or additional injectable boluses. Though common in other species, intravenous (IV) continuous-rate infusions (CRI) using guaifenesin combinations have not been evaluated in ursids. This study evaluated the use of a CRI compared to an inhalant for maintenance anesthesia. Seven healthy American black bears (Ursus americanus) were anesthetized in a crossover design with two different anesthetic maintenance protocols. Bears were immobilized with ketamine (2.02 ± 0.14 mg/kg) and medetomidine (0.04 ± 0.003 mg/kg) for both protocols. The anesthetic maintenance control protocol consisted of isoflurane gas (ISO) started at 2% delivered by endotracheal tube; the experimental protocol consisted of guaifenesin, medetomidine, ketamine (GMK) IV CRI started at 50 mg/kg/hr guaifenesin, 0.01 mg/kg/hr medetomidine, and 1 mg/kg/hr ketamine. Induction and recovery parameters including time to first effect, recumbency, and hands on; duration of maintenance protocol; and time from reversals administered to head up, standing on all four feet, no ataxia, and to fully recovered were recorded and compared between protocols. Heart rate, respiratory rate, rectal temperature, blood pressure, end tidal carbon dioxide, and hemoglobin oxygen saturation were recorded at 5-min intervals and compared between protocols. Venous blood gases were obtained at the start, middle, and end of the maintenance anesthesia and compared between protocols. All bears exhibited hypertension with mild respiratory acidosis throughout procedures. Measured physiologic parameters did not differ significantly between the isoflurane and the GMK CRI maintenance protocols, with the exception of higher endpoint (ISO) pCO2 measurements. No adverse events were recorded with either protocol, and adequate depth of anesthesia was maintained with both protocols. GMK CRI provides a safe, effective, and more portable alternative to inhalant anesthetics for maintenance anesthesia in bears in captivity or in the field.

Influence of the position of charcoal air-filtration canisters on the efficacy of waste isoflurane scavenging as assessed in a randomized experiment.

OBJECTIVE To determine whether the position or elevation of charcoal air-filtration canisters would impact efficacy of waste anesthetic gas (WAG) scavenging. DESIGN Randomized experiment. SAMPLE 2 types of bottom-vented and 1 type of top-vented charcoal air-filtration canisters (n = 8 of each canister type/evaluation session). PROCEDURES Canisters were evaluated in a vertical or horizontal position at both low and high isoflurane gas flow rates in a modified Bain nonrebreathing circuit. Waste anesthetic gas concentrations were measured 2.54 cm from canister exhaust ports with an ambient air analyzer every 30 seconds for a maximum of 15 min/experimental condition. One type of bottom-vented canister was tested in a vertical position elevated above or suspended below the vaporizer at a high isoflurane flow rate and then a standard maintenance flow rate. RESULTS Position had no significant effect on WAG emission by any canister type at low isoflurane flow rates. Horizontally positioned bottom-vented canisters at the high isoflurane flow rate emitted significantly more WAG than vertically positioned canisters. Horizontally positioned top-vented canisters at high flow rates emitted significantly more WAG than vertically positioned canisters at the final 15-minute time point only. Cannister types differed significantly in intercanister variability. Canister elevation relative to the vaporizer had no impact on WAG scavenging efficacy. CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that charcoal air-filtration canisters should be used in a vertical position when anesthetizing animals with the anesthetic delivery system used in this study.

Surgical treatment of large intestinal intussusception in a Rottweiler puppy

A 3-month Rottweiler female dog approximately weighing 5 kg was referred to veterinary clinic with history of defecation ceasing symptoms for about 48 h. In the clinical examinations, anorexia, lethargy, and frequent vomiting were observed. The blood work showed an increase in neutrophils. The mucosa was dark color and the animal CRT was increased. According to the clinical symptoms and blood work findings, a simple radiograph was considered to be taken from the abdominal cavity and the layering of gas-filled intestine was seen, which decided to take the radiograph with the contrast media. In the radiologic examination, intussusception was diagnosed and immediately decided to do exploratory laparotomy. Anesthesia was induced in animal with ketamine (30 mg/kg) and midazolam (0.2 mg/kg) and maintained by isoflurane gas (2% in 98% oxygen). All viscera were exposed to surgeon and hyperemic, distended intestine with obvious intussusception was diagnosed in ileocolic region with the length of 8 cm. With distance of 5 cm from each side of affected area was chosen, enterectomy and anastomosis were performed. After the leak test and the absence of leakage of the contents, on the intestine suture lining, greater omentum was patched and fixed with a few stitches to enhancing the healing in the suture line. Postoperatively, the animal received systemic antibiotics (Ceftriaxone 20 mg/kg) for 7 days and fed by soft commercial food like fish or chicken soup. The case treated successfully after 10 days and discharged without any complication.

A Mixture of Butorphanol, Azaperone, and Medetomidine for the Immobilization of American Beavers ( Castor canadensis).

A total of 58 American beavers ( Castor canadensis) was immobilized with butorphanol, azaperone, and medetomidine (BAM) for the purpose of health assessments, sex determination, and placement of very high-frequency tail transmitters in a subset of animals. Isoflurane gas anesthesia was available to aid with induction when needed, and all animals received supplementary oxygen. Thirty-one beavers immobilized with a mean (SD) dose of 0.65 (0.15) mg/kg butorphanol, 0.22 (0.05) mg/kg azaperone, and 0.26 (0.06) mg/kg medetomidine did not require supplemental isoflurane during induction and the mean induction time was 8 min (range: 3-21 min). This dose was equivalent to 0.024 (0.005) mL of BAM per kilogram. A total of 29 beavers that were immobilized with a mean (SD) of 0.51 (0.07) mg/kg butorphanol, 0.17 (0.02) mg/kg azaperone, and 0.2 (0.03) mg/kg medetomidine needed supplementary isoflurane at 5% and 5 L/min for <1 min to induce full anesthesia. In none of the beavers did BAM alone provide sufficient depth of anesthesia to drill a hole in the tail for transmitter placement, and supplementary isoflurane was administered to reach a sufficient level of analgesia for the procedure. The beavers were reversed with 5 mg of atipamezole per milligram of medetomidine and 1 mg of naltrexone per milligram of butorphanol. No adverse effects or mortalities were observed. Butorphanol-azaperone-medetomidine can be considered safe for use in American beavers for minor procedures.

In Vivo Imaging of Microvasculature during Anesthesia with High-Resolution Photoacoustic Microscopy

Anesthesia monitoring is extremely important in improving the quality of anesthesia and ensuring the safety of patients in operation. Photoacoustic microscopy (PAM) is proposed to in vivo image the skin microvasculature of 10 nude mice undergoing general anesthesia by using the isoflurane gas with a concentration of 3%. Benefiting from strong optical absorption of hemoglobin, PAM has good contrast and high resolution in mapping of microvasculature. A series of high quality images can clearly reveal the subtle changes of capillaries in morphology over time. Two indices, vessel intensity and vessel density, are extracted from these images to measure the microvasculature quantitatively. The imaging results show that the vessel intensity and density are increased over time. After 65 min, the vessel intensity increased 42.7 ± 8.6% and the density increased 28.6 ± 12.2%. These indices extracted from photoacoustic images accurately reflect the greater blood perfusion undergoing general anesthesia. Additionally, abnormal reductions of vessel intensity and density are also observed as overtime anesthesia. This preclinical study suggests that PAM holds potential to monitor anesthesia by imaging the skin microvasculature.

Effect of isoflurane alone or in combination with meloxicam on the behavior and physiology of goat kids following cautery disbudding

Cautery disbudding of goat kids is painful, but may be alleviated with pain mitigation. We therefore evaluated the effect of administering general anesthesia (isoflurane) or a nonsteroidal anti-inflammatory drug (meloxicam) on goat kid behavior and physiology following cautery disbudding. Trial 1 (n = 12/treatment) evaluated behavioral responses in 72 female Saanen dairy goat kids (mean ± standard error of the mean; 3.9 ± 0.15 d old) and trial 2 (n = 10/treatment) evaluated physiological responses in 60 female Saanen dairy goat kids (4.3 ± 0.14 d old). Goat kids were randomly assigned to 1 of 6 treatment groups that were either (1) sham-handled only (simulated disbudding; SHAM) or disbudded with (2) no pain relief (CAUT), (3) isoflurane gas (ISO), (4) isoflurane and s.c. meloxicam combined (ISO+MEL), (5) meloxicam s.c. (0.5 mg/kg of body weight; I-MEL), or (6) oral meloxicam (0.2 mg/kg of body weight; O-MEL). Head shaking, head scratching, self-grooming, feeding, and body shaking were continuously video recorded for 24 h pre- and post-treatment. Lying behavior was recorded continuously for 24 h pre- and post-treatment using accelerometers. Plasma cortisol, glucose, and lactate concentrations were measured from blood samples collected immediately before treatment (baseline) and at 15, 60, and 120 min post-treatment. Body temperature was measured immediately after blood sampling at all blood sampling time points. Head shaking and body shaking frequencies were 50% higher in CAUT than SHAM kids 5 min post-treatment; ISO+MEL and ISO kids performed 25% less body shakes than CAUT kids. Head scratching durations 1 h post-treatment were higher in CAUT than SHAM kids, whereas O-MEL were similar to SHAM kids from 2 h post-treatment. Self-grooming, feeding, and lying did not differ between groups. Cortisol concentrations were higher in CAUT than SHAM kids (156.4 ± 26.41 and 104.1 ± 26.41 nmol/L, respectively), whereas ISO+MEL and ISO kids (88.3 ± 26.41 and 113.2 ± 26.41 nmol/L, respectively) had lower cortisol concentrations than CAUT kids over the 2-h sampling period. Moreover, O-MEL and I-MEL kids (163.0 ± 26.41 and 130.9 ± 26.41 nmol/L, respectively) had similar cortisol concentrations to CAUT kids. We found no evidence that plasma glucose and lactate concentrations or body temperature were affected by treatment. The administration of isoflurane, with or without meloxicam, appeared to reduce pain associated with cautery disbudding.