Period Of Anesthesia Research Articles

Ketamine and propofol have opposite effects on postanesthetic sleep architecture in rats: relevance to the endogenous sleep-wakefulness substances orexin and melanin-concentrating hormone.

Anesthesia and surgery disturb sleep. Disturbed sleep adversely affects postoperative complications involving the cardiovascular system, diabetes, and infection. General anesthetics share neuronal mechanisms involving endogenous sleep-wakefulness-related substances, such as orexin (OX) and melanin-concentrating hormone (MCH). We evaluated changes in sleep architecture and the concentration of OX and MCH during the peri-anesthetic period. To examine sleep architecture, male Sprague-Dawley rats weighing 350-450g received ketamine 100mg/kg (n=9) or propofol 80mg/kg (n=6) by intraperitoneal injection. Electroencephalography was recorded from 2days pre- to 5days postanesthesia. To quantify levels of OX and MCH, 144 similar rats received the same doses of ketamine (n=80) or propofol (n=64). Brain concentrations of these substances were determined at 0, 20, 60, and 120min after anesthetic administration. Ketamine decreased OX content in the hypothalamus during the anesthesia period. OX content was restored to pre-anesthesia levels in the hypothalamus and pons. Both anesthetics increased brain MCH content in the postanesthetic period, with the degree of increase being greater with propofol. Ketamine enhanced wakefulness and inhibited non-rapid eye movement sleep (NREMS) immediately after anesthesia. Conversely, propofol inhibited wakefulness and enhanced NREMS in that period. Ketamine inhibited wakefulness and enhanced NREMS during the dark phase on the first postanesthesia day. Anesthetics affect various endogenous sleep-wakefulness-related substances; however, the modulation pattern may depend on the type of anesthetic. The process of postanesthetic sleep disturbance was agent specific. Our results provide fundamental evidence to treat anesthetic-related sleep disturbance.

Hipotermia dan Waktu Pemulihannya dalam Anestesi Gas Isofluran dengan Induksi Ketamin-Xylazin pada Anjing (HYPOTHERMIA AND ITS RECOVERY IN GAS ISOFLURANE ANESTHESIA WITH KETAMINE-XYLAZINE INDUCTION ON DOGS)

The most common effect occurred during anaesthesia is the decrease of body temperature. Technologicaldevelopment has enabled the used the latest innovations in order to to increase the efficacy and the safetyof anaesthesia. The purpose of this study was to determine the effect of ketamine-xylazine injection onhypothermia and its recovery at dog which anesthetized with isoflurane. Ten healthy dogs were dividedinto two groups with each group consisted offive dogs. In Group A, dogs were given premedication (atropinesulfate 0.04 mg/kg) and then anaesthetized with isoflurane gas (4% for induction dose and 1% for themaintenance dose). In Group B dogs were given premedication atropine sulfate (0.04 mg/kg) and ketamineHCl induction solution (10 mg/kg) mixed with xylazine HCl (2 mg/kg), and anaesthetized with isofluranegas (maintenance dose of 1%). Adaptation period was conducted in one week. Body temperature wasmeasured before, during, and after the duration of anaesthesia. The data was analyzed statistically by arepeated Anova test. This study found that the mean body temperature of dogs in Group A decreased from37,88±0,51 oC to 34,64±0,95 oC over a period of anaesthesia, and the recovery time was over 40 minutespost-anaesthesia. In Group B, body temperature decreased from 38.06±0.42 oC to 34.96±1.23 oC, and therecovery time was 90 minutes. In conclusion, the use of ketamine-xylazine in isoflurane anaesthesiaprocedures on dogs, would need post-anaesthesia preparation procedure regarding with hypothermia andits recovery.

The effect of two different intra-operative end-tidal carbon dioxide tensions on apnoeic duration in the recovery period in horses

ObjectiveTo compare the effect of two different intraoperative end-tidal carbon dioxide tensions on apnoeic duration in the recovery period in horses. Study designProspective randomized clinical study. AnimalsEighteen healthy client-owned adult horses (ASA I–II) admitted for elective surgery. Horses were of a median body mass of 595 (238–706) kg and a mean age of 9 ± 5 years. MethodsA standardized anaesthetic protocol was used. Horses were positioned in dorsal recumbency and randomly allocated to one of two groups. Controlled mechanical ventilation (CMV) was adjusted to maintain the end-tidal carbon dioxide tension (Pe’CO2) at 40 ± 5 mmHg (5.3 ± 0.7 kPa) (group40) or 60 ± 5 mmHg (8.0 ± 0.7 kPa) (group60). Arterial blood gas analysis was performed at the start of the anaesthetic period (T0), at one point during the anaesthetic (T1), immediately prior to disconnection from the breathing system (T2) and at the first spontaneous breath in the recovery box (T3). The time from disconnection from the breathing system to return to spontaneous ventilation (RSV) was recorded. Data were analysed using a two sample t-test or the Mann–Whitney U-test and significance assigned when p < 0.05. ResultsHorses in group60 resumed spontaneous breathing significantly earlier than those in group40, [52 (14–151) and 210 (103–542) seconds, respectively] (p < 0.001). Arterial oxygen tension (PaO2), pH, base excess (BE) and plasma bicarbonate ( HCO3-) were not different between the groups at RSV, however, PaO2 was significantly lower in group60 during (T1) and at the end of anaesthesia (T2). Conclusions and clinical relevanceAiming to maintain intra-operative Pe’CO2 at 60 ± 5 mmHg (8.0 ± 0.7 kPa) in mechanically ventilated horses resulted in more rapid RSV compared with when Pe’CO2 was maintained at 40 ± 5 mmHg (5.3 ± 0.7 kPa).

Etomidate exposure in early infant mice (P10) does not induce apoptosis or affect behaviour.

Numerous animal studies have shown that all commonly used intravenous anaesthetic drugs and volatile agents may cause neuronal apoptosis following exposure in early life. Most studies have focussed on detecting increased apoptosis but their methods are not always readily transferrable to humans. The lipid formulation of etomidate represents an alternative to the currently established intravenous anaesthetic agents but there is no animal or human data on apoptosis or long-term behavioural changes. The aim of our study was to investigate the effects of etomidate on cerebral neuronal apoptosis and long-term behavioural effects using an established mouse model that represents the clinically relevant period of anaesthesia during early infancy in humans. Six groups of 10 day old mice (P10) were injected with either etomidate 0.3, 3 or 10 mg/kg, propofol 60 mg/kg, ketamine 50 mg/kg or placebo only. Apoptosis in the cerebral cortex and hippocampus was assessed 24 h after treatment (activated caspase-3). Late behavioural effects were tested at 2 months of age (spontaneous activity in a new environment). No evidence was found of differences in activated caspase 3-concentrations among the study groups. Significant late behavioural changes were only observed in the ketamine group. A single dose of etomidate in early infant mice at P10 did not produce evidence of cerebral apoptosis or impaired adult motor behaviour.

The association between complications in patients during the anesthetic recovery period and the physiological conditions experienced in the preoperative period

The aim of this research is to verify the correlation between the patient’s underlying diseases in the preoperative period and the occurrence of complications during the anesthetic recovery period. This is a quantitative field research, with a non-experimental design, comparative, and prospective. The sample is part of a big study conducted with 42 patients. For this research was selected 24 patients, who were submitted to elective surgery, under general anesthesia, with the American Society Anesthesiologists (ASA) status classification I or II; also they should be healthy and do not have any of the comorbidities listed as a criteria of exclusion from the study. The most common complications found were pain, hypoxia, hypothermia, and changes level of consciousness. Comparing this result with the results obtained with the initial study (conducted with 42 patients), regardless of whether the patient has or not comorbidities or mild diseases, which led them to the surgical procedure, the triad of complications, composed of pain, hypoxemia and hypothermia were the most frequent during the first 60 minutes of patient permanence in the PACU. In the manual analysis of the questionnaires, it was not verified significant agreement between the most common clinical manifestations and the presence of comorbidities. It is recommended that further studies should be conducted in order to properly address the complications presented by patients without comorbidities, when in the anesthetic recovery period.

Combining isoflurane anesthesia with midazolam and butorphanol in rats.

Representative inhalant anesthetic agent, isoflurane is commonly used during surgery in rats. However, isoflurane mediates relatively strong respiratory depression. In human and veterinary medicine, sedatives and analgesics are co-administered to complement the anesthetic action of inhalant anesthesia. The present study aimed to establish the novel balanced anesthesia that combines midazolam and butorphanol with isoflurane (MBI) in rats. Male Sprague Dawley rats were divided into 2 groups, and administered either isoflurane monoanesthesia or isoflurane with midazolam (2.5 mg/kg, ip) and butorphanol (2.0 mg/kg, ip). The minimum alveolar concentration (MAC) in each group was evaluated. Induction and recovery times were measured in each group. Adverse reactions during induction were also recorded. In each group, vital signs were assessed for 1 h under 1.5×MAC of isoflurane. Instability of vital signs was assessed under each anesthesia by calculating coefficient of variance. Compared with isoflurane monoanesthesia, MBI anesthesia caused 32% MAC reduction (isoflurane monoanesthesia: 1.30 ± 0.09%, MBI 0.87 ± 0.08%, P<0.05). MB premedication mediated smooth sedating action with low incidence of adverse reactions such as urination and defecation. Isoflurane monoanesthsesia remarkably decreased respiratory rate and saturation O2 (SPO2). In contrast, MBI anesthesia resulted in a relatively stable respiratory rate without decreases in SPO2 during the anesthetic period. In summary, MB premedication is effective for attenuating respiratory depression induced by isoflurane, and achieving smooth induction. This anesthetic protocol serves as a novel option for appropriate anesthesia in rats.

Spectral Gini Index for Quantifying the Depth of Consciousness.

We propose indices that describe the depth of consciousness (DOC) based on electroencephalograms (EEGs) acquired during anesthesia. The spectral Gini index (SpG) is a novel index utilizing the inequality in the powers of the EEG spectral components; a similar index is the binarized spectral Gini index (BSpG), which has low computational complexity. A set of EEG data from 15 subjects was obtained during the induction and recovery periods of general anesthesia with propofol. The efficacy of the indices as indicators of the DOC was demonstrated by examining Spearman's correlation coefficients between the indices and the effect-site concentration of propofol. A higher correlation was observed for SpG and BSpG (0.633 and 0.770, resp., p < 0.001) compared to the conventional indices. These results show that the proposed indices can achieve a reliable quantification of the DOC with simplified calculations.

General anaesthesia for parturients with spondyloepiphyseal dysplasia: Risky but possible!

Sir, A 28-year-old primigravida, 135 cm tall and a known case of spondyloepiphyseal dysplasia (SED), with 37 weeks of gestation, was scheduled for elective caesarean section. The patient was unable to walk and was wheelchair bound. The flexion deformity of the knee joint, as well as the hip joint, made it difficult for the patient to lie down straight [Figure 1]. In addition, she had flexion deformities of the elbow and wrist joints.Figure 1: Patient with fixed flexion deformities of the knee and hip jointsThe patient was the first child of her parents who had non-consanguineous marriage. The other siblings of the patient also had similar deformities. Patient's biochemical, haematological investigations, echocardiography and pulmonary function tests were unremarkable. The patient had limited neck movements but had modified Mallampati Airway Class 3. The patient's neck extension was two-thirds restricted and her mouth opening was about 40 mm. Other airway parameters were within normal limits. Examination of the spine revealed scoliosis, and intervertebral spaces were difficult to palpate. Radiographic examination (pre-pregnancy) revealed platyspondyly, reduced disc height as well as features of premature secondary arthritis in both hip joints [Figure 2]. She was unable to position herself for regional anaesthesia. The fixed flexion deformity of the knee prevented lateral supine positioning of the patient. She could sit with two pillows behind her back and a pillow below her knee, and slept in head-up position.Figure 2: X-ray of the hip joints showing early osteoarthritis resulting in fixed flexion deformityThe patient did not consent for regional anaesthesia. Hence, it was decided to conduct caesarean section under general anaesthesia. She was positioned with a pillow under the knees along with a wedge under the abdomen. The head was also supported on a head ring with two pillows below her head. Intravenous line was secured with an 18 gauge cannula and infusion of Ringer lactate was started. Routine monitors were connected and basal readings noted. Awake nasal fibre-optic intubation was performed with small size of endotracheal tube (ETT) using cuffed polyvinyl chloride 6.5 mm ETT uneventfully. The rest of the anaesthetic and post-operative period was uneventful. SED is an extremely rare genetic entity with incidence of 1–4 per million. Regional anaesthesia is the method of choice in parturients with SED although it is technically difficult and has variable effects. Administration of general anaesthesia in such patients is not without risks. The presence of kyphoscoliosis in SED may lead to significant respiratory compromise that gets exaggerated in pregnancy due to diaphragmatic splinting caused by gravid uterus.[1] Pregnancy further exaggerates the already existing respiratory compromise and enhances aortocaval compression. The presence of atlantoaxial instability due to odontoid hypoplasia, central anterior pointing of the cervical spine along with ligamentous laxity in SED may increase the risk of severe spinal cord compression. Tetraparesis has been reported after intubation in these patients due to cervical spine instability.[2] Pregnancy also poses an added risk for aspiration.[1] Patients with SED may have associated laryngotracheal stenosis, which may pose difficulty in airway management. There are reports of intubation being guided by lightwand.[3] Intubation with video laryngoscope could be another tangible alternative.[4] However, video laryngoscope was unavailable during intubation in the management of the present patient. Thus, patients with SED with pregnancy can pose a special challenge for the anaesthesiologist. However, while administering general anaesthesia, proper assessment and monitoring for cervical spine stability and respiratory status, positioning of the patient so as to prevent any untoward neurological injury and meticulous planning of airway management and perioperative care may go a long way in successful outcome. Declaration of Patient Consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Acknowledgement We would like to acknowledge Dr. P. N. Gupta, Associate Professor, Department of Orthopaedics, Government Medical College and Hospital, Chandigarh, for his help.

Analysis of the level of consciousness related to the oxygen therapy in patients in anesthesia recovery period

Analyze the level of consciousness by means of the Aldrete-Kroulik scale associated with the use of oxygen therapy at the Post-Anesthesia Care Unit (PACU). It is a prospective and comparative study, with quantitative analysis. It was conducted in a big Federal Public Hospital, located in Belo Horizonte city. The sample was consisted of 60 subjects, separated between groups using and do not using oxygen therapy, aged between 18 and 64 years old, submitted to elective surgery, surgical site in upper torso, under general anesthesia, and with the American Society Anesthesiologists (ASA) status I or II. The most part of the patients were female, with 50 years old or older, classified as ASA II, under total intravenous anesthesia, and length of time of anesthesia over 240 minutes. In the analysis of the level of consciousness related to the use of oxygen therapy, it is noteworthy that the p-value (0.069) is significant at the 15 minutes of permanence in the PACU. A large number of patients from the group that received supplemental oxygen therapy showed improvement in the level of consciousness at the 15 minutes of permanence in the PACU. Team work is necessary to prevent patient’s complications in anesthetic recovery period.

Impact evaluation of two different general anesthesia protocols (TIVA with propofol vs isoflurane) on the total number of interventions to treat cardiovascular depression or arousal/movement episodes in dogs undergoing orthopedic surgery receiving an intrathecal anesthesia.

The aim of this prospective, randomized clinical trial was to compare the total number of anesthetic interventions (TNAI) performed by the anesthetist to treat cardiovascular depression or arousal/movement episodes in dogs receiving intrathecal and general anesthesia (GA), maintained using propofol-based TIVA (group P) or isoflurane (group I). Mean arterial pressure (MAP) before (T0) and 12 min after intrathecal anesthesia (T1) and intraoperative vasoactive consumption were also compared. The TNAI to deepen the anesthetic plane or to treat hemodynamic depression in the pre-surgical and intra-surgical period was calculated in forty-two client-owned dogs randomly assigned to group P or I. Ten dogs for each group complied with the inclusion criteria and were analyzed. In pre-surgical period, the TNAI was higher in Group I [2 (0–5)] than Group P [0 (0–2)] (P=0.022), and ephedrine consumption was also higher in Group I [75 (0–200) µg/kg)] than Group P [(0 (0–50)] (P=0.016). MAP (mmHg) in Group P was 79 (66–95) at T0 and 65 (59–86) at T1 and 67.5 (50–73) and 57 (53–66) in Group I, respectively. At T0 and T1, MAP was higher in Group P (P=0.005 and P=0.006, respectively). No differences were found between the two groups in the intrasurgical period (P>0.05). This study shows that the GA protocol can have a relevant impact on the TNAI performed by the anesthetist in the pre-surgical period of anesthesia, to treat cardiovascular depression or arousal/movement episodes in dogs receving intrathecal anesthesia.

Are there any effects of Sevoflurane and Desflurane anaesthesia on blood glucose levels in acute hyperglycemic diabetic rats?

The aim of this study was to investigate blood glucose level of desflurane and sevoflurane on blood glucose in diabetic rats undergoing acute hyperglycemia. In this study, 30 male Wistar albino rats were included. Diabetes was induced by a single IP injection of streptozotocin. After the effects of chronic diabetes encountered, diabetic rats were randomly assigned into diabetic control (group DC), diabetic hyperglycemia group (group DH), diabetic hyperglycemia group with desflurane (group DH-D), and diabetic hyperglycemia group with sevoflurane (group DH-S) groups. The normoglycemic groups received an IP injection of the same amount of saline. Hyperglycemic diabetic rats were anaesthetized by desflurane 6 % or sevoflurane 2 % at a dose, by which minimal alveolar concentration (MAC) for rats would be one. The drugs were given for 4 hours within 100 % oxygen at a rate of 6 L.min-1. One hour after cessation of inhalation anesthesia, blood glucose levels were determined at 1st, 4th and 24th hours. 24 hours after the anaesthesia. Serum glucose was detected to be significantly lower in Group C, when compared to Groups DC, DH, DH-D and DH-S (p = 0.002, p = 0.001, p = 0.002, p = 0.003, respectively). Blood glucose levels in the diabetic groups were similar at the end of 6 weeks period, after hyperglycemia and anaesthesia induction. We found out that sevoflurane and desflurane administrations in hyperglycemic rats were both related with insignificant blood glucose level increase at early post anaesthesia period and at post anaesthesia 24th hours. We still think that patients undergoing anaesthesia protocols with acute hyperglycemia need relatively longer follow up periods (Tab. 1, Ref. 28).

The Effect of Doxapram on Cardiopulmonary Function in Dogs under Total Intravenous Anesthesia with Remifentanil and Propofol

We investigated the effect of constant rate infusion (CRI) with doxapram on cardiopulmonary function during total intravenous anesthesia (TIVA) with remifentanil and propofol CRI in dogs. Fifteen male Beagle dogs were randomly divided into 3 groups. All groups were premedicated with medetomidine (20 μg/kg, IV) and anesthetized by remifentanil/propofol CRI for one and half hour. At the initiating of the anesthesia, different doses of doxapram for each group were administrated as the followings; D1 group - doxapram 0.25 mg/kg bolus followed by doxapram 8.33 μg/kg/min, D2 group - doxapram 2 mg/kg bolus followed by doxapram 66.66 μg/kg/min, control group - normal saline. The anesthetic depth for surgery was well maintained in all groups throughout the anesthetic periods. The respiratory rate was significantly higher in D2 group than that of control group (p < 0.05). The values of PaO₂ and SaO₂ were significantly increased in both D1 and D2 groups compared with control group (p < 0.05). High dose of doxapram (D2 group) significantly decreased the level of PaCO₂ compared with control group (p < 0.05). The values of systolic, mean and diastolic arterial pressure were significantly increased in doxapram 2 group (p < 0.05). There were no significant differences in the values of heart rate and pH of arterial blood. Therefore, doxapram CRI may be useful to alleviate the suppression of cardiopulmonary function including hypoxia and hypotension during TIVA with remifentanil and propofol in dogs.

Time Required between Two Positioning Methods for Shoulder Arthroscopy. A Non-Randomized Controlled Study

Purpose: The objective of this non-randomized controlled study of 40 patients was to compare the positioning time required between the beach chair (20 patients) and the lateral decubitus position (20 patients) for a shoulder arthroscopy. Methods: A single evaluator measured the speed of setup and the time was divided in four periods. All surgeries were performed at a single hospital by two fellowship-trained upper extremity orthopaedic surgeons using the SPIDER Limb positioner (Smith Nephew, Memphis, TN, USA) and under regional and general anaesthesia. The anaesthesia period was performed with the patient’s supine before the positioning. Results: The time required from positioning to the first incision is faster in lateral decubitus than in beach chair position (18:28 min vs 22:44 min, p < 0.0001). The setup time by the beneficiary attendant (10:13 min vs 14:12 min, p < 0.0001) and the time to set up the operative fields (7:42 min vs 8:39 min, p = 0.006) also indicate the same tendency. The duration of the anaesthetic period, excluding the time required for the regional block, is also faster in the lateral decubitus position (13:40 min vs 17:09 min, p = 0.17). Moreover, the correlation between weight and time positioning is inversely proportional in lateral decubitus position and proportional in beach chair position.

Perioperative evaluation of respiratory impedance using the forced oscillation technique: a prospective observational study.

BackgroundIntravascular fluid shifts, mechanical ventilation and inhalational anesthetic drugs may contribute to intraoperative lung injury. This prospective observational study measured the changes in respiratory impedance resulting from inhalational anesthesia and mechanical ventilation in adults undergoing transurethral resection of bladder tumors. The components of respiratory impedance (resistance and reactance) were measured using the forced oscillation technique (FOT).MethodsRespiratory resistance at 5 Hz (R5) and 20 Hz (R20), respiratory reactance at 5 Hz (X5), resonant frequency (Fres) and area of low reactance (ALX) were measured before and immediately after surgery in 30 adults. In addition, preoperative vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1.0) were evaluated using spirometry. All patients were intubated with an endotracheal tube and were mechanically ventilated, with anesthesia maintained with sevoflurane. Pre- and postoperative FOT measurements were compared using Wilcoxon paired rank tests, and the relationships between FOT measurements and preoperative spirometry findings were determined by Spearman’s rank correlation analysis.ResultsTwenty-six patients were included in the final analysis: postoperative FOT could not be performed in four because of postoperative restlessness or nausea. The mean duration of surgery was 47 min. All components of respiratory resistance deteriorated significantly over the course of surgery, with median increases in R5, R20, and R5–R20 of 1.67 cmH2O/L/s (p < 0.0001), 1.28 cmH2O/L/s (p < 0.0001) and 0.46 cmH2O/L/s (p = 0.0004), respectively. The components of respiratory reactance also deteriorated significantly, with X5 decreasing 1.7 cmH2O/L/s (p < 0.0001), Fres increasing 5.57 Hz (p < 0.0001) and ALX increasing 10.51 cmH2O/L/s (p < 0.0001). There were statistically significant and directly proportional relationships between pre- and postoperative X5 and %VC, %FEV1.0 and %FVC, with inverse relationships between pre- and postoperative Fres and ALX.ConclusionsAll components measured by FOT deteriorated significantly after a relatively short period of general anesthesia and mechanical ventilation. All components of resistance increased. Of the reactance components, X5 decreased and Fres and ALX increased. Pre- and postoperative respiratory reactance correlated with parameters measured by spirometry.Trial registration JMA-IIA00136.

Rapid and Efficient Production of Coronary Artery Ligation and Myocardial Infarction in Mice Using Surgical Clips.

AimsThe coronary artery ligation model in rodents mimics human myocardial infarction (MI). Normally mechanical ventilation and prolonged anesthesia period are needed. Recently, a method has been developed to create MI by popping-out the heart (without ventilation) followed by immediate suture ligation. Mortality is high due to the time-consuming suture ligation process while the heart is exposed. We sought to improve this method and reduce mortality by rapid coronary ligation using a surgical clip instead of a suture.Methods and ResultsMice were randomized into 3 groups: clip MI (CMI), suture MI (SMI), or sham (SHAM). In all groups, heart was manually exposed without intubation through a small incision on the chest wall. Unlike the conventional SMI method, mice in the CMI group received a metal clip on left anterior descending artery (LAD), quickly dispensed by an AutoSuture Surgiclip™. The CMI method took only 1/3 of ligation time of the standard SMI method and improved post-MI survival rate. TTC staining and Masson’s trichrome staining revealed a similar degree of infarct size in the SMI and CMI groups. Echocardiograph confirmed that both SMI and CMI groups had a similar reduction of ejection fraction and fraction shortening over the time. Histological analysis showed that the numbers of CD68+ macrophages and apoptotic cells (TUNEL-positive) are indistinguishable between the two groups.ConclusionThis new method, taking only less than 3 minutes to complete, represents an efficient myocardial infarction model in rodents.

Incidence of Inadvertent Intraoperative Hypothermia and Its Risk Factors in Patients Undergoing General Anesthesia in Beijing: A Prospective Regional Survey.

Background/ObjectiveInadvertent intraoperative hypothermia (core temperature <360 C) is a recognized risk in surgery and has adverse consequences. However, no data about this complication in China are available. Our study aimed to determine the incidence of inadvertent intraoperative hypothermia and its associated risk factors in a sample of Chinese patients.MethodsWe conducted a regional cross-sectional survey in Beijing from August through December, 2013. Eight hundred thirty patients who underwent various operations under general anesthesia were randomly selected from 24 hospitals through a multistage probability sampling. Multivariate logistic regression analyses were applied to explore the risk factors of developing hypothermia.ResultsThe overall incidence of intraoperative hypothermia was high, 39.9%. All patients were warmed passively with surgical sheets or cotton blankets, whereas only 10.7% of patients received active warming with space heaters or electric blankets. Pre-warmed intravenous fluid were administered to 16.9% of patients, and 34.6% of patients had irrigation of wounds with pre-warmed fluid. Active warming (OR = 0.46, 95% CI 0.26–0.81), overweight or obesity (OR = 0.39, 95% CI 0.28–0.56), high baseline core temperature before anesthesia (OR = 0.08, 95% CI 0.04–0.13), and high ambient temperature (OR = 0.89, 95% CI 0.79–0.98) were significant protective factors for hypothermia. In contrast, major-plus operations (OR = 2.00, 95% CI 1.32–3.04), duration of anesthesia (1–2 h) (OR = 3.23, 95% CI 2.19–4.78) and >2 h (OR = 3.44, 95% CI 1.90–6.22,), and intravenous un-warmed fluid (OR = 2.45, 95% CI 1.45–4.12) significantly increased the risk of hypothermia.ConclusionsThe incidence of inadvertent intraoperative hypothermia in Beijing is high, and the rate of active warming of patients during operation is low. Concern for the development of intraoperative hypothermia should be especially high in patients undergoing major operations, requiring long periods of anesthesia, and receiving un-warmed intravenous fluids.

A comparison of different synchronization measures in electroencephalogram during propofol anesthesia

Electroencephalogram (EEG) synchronization is becoming an essential tool to describe neurophysiological mechanisms of communication between brain regions under general anesthesia. Different synchronization measures have their own properties to reflect the changes of EEG activities during different anesthetic states. However, the performance characteristics and the relations of different synchronization measures in evaluating synchronization changes during propofol-induced anesthesia are not fully elucidated. Two-channel EEG data from seven volunteers who had undergone a brief standardized propofol anesthesia were then adopted to calculate eight synchronization indexes. We computed the prediction probability (P K ) of synchronization indexes with Bispectral Index (BIS) and propofol effect-site concentration (C eff ) to quantify the ability of the indexes to predict BIS and C eff . Also, box plots and coefficient of variation were used to reflect the different synchronization changes and their robustness to noise in awake, unconscious and recovery states, and the Pearson correlation coefficient (R) was used for assessing the relationship among synchronization measures, BIS and C eff . Permutation cross mutual information (PCMI) and determinism (DET) could predict BIS and follow C eff better than nonlinear interdependence (NI), mutual information based on kernel estimation (KerMI) and cross correlation. Wavelet transform coherence (WTC) in α and β frequency bands followed BIS and C eff better than that in other frequency bands. There was a significant decrease in unconscious state and a significant increase in recovery state for PCMI and NI, while the trends were opposite for KerMI, DET and WTC. Phase synchronization based on phase locking value (PSPLV) in δ, θ, α and γ1 frequency bands dropped significantly in unconscious state, whereas it had no significant synchronization in recovery state. Moreover, PCMI, NI, DET correlated closely with each other and they had a better robustness to noise and higher correlation with BIS and C eff than other synchronization indexes. Propofol caused EEG synchronization changes during the anesthetic period. Different synchronization measures had individual properties in evaluating synchronization changes in different anesthetic states, which might be related to various forms of neural activities and neurophysiological mechanisms under general anesthesia.

Effects of transport, fasting and anaesthesia on the faecal microbiota of healthy adult horses.

The intestinal microbiota is important for health and disease. Factors that disturb the equine intestinal microbiota need further investigation. To determine the effects of transport, fasting and anaesthesia on the faecal microbiota of healthy adult horses using next-generation sequencing. Experimental trial. Faecal samples were taken from 8 horses at baseline, after transport, 12h of fasting and 24, 48 and 72h after a 6h anaesthesia. Next generation sequencing of the V4 region of the 16S rRNA gene was used to assess the microbial composition of faeces. Alpha diversity, phylogenetic structures and beta diversity were assessed. There were significant changes in the relative abundances of phyla, classes, orders and families after transport, fasting and anaesthesia. Most notably horses had a significantly lower abundance of Clostridiales after transport compared with baseline (P=0.03) and a decreased abundance of Rickettsiales after fasting (P=0.024). Alpha diversity was not significantly different between time points (all P>0.21). When parsimony analysis was applied, anaesthesia had a significant effect on community membership and structure (Jaccard index and Yue and Clayton index both P=0.02). There was some effect of transport, fasting and anaesthesia on the composition and structure of the microbiota of healthy horses. This indicates these are potentially stress factors for the equine intestinal microbiota. Further investigation is required to look at the potential impact of changes in the microbiota on the development of disease in the post anaesthetic period.

Intravenous sufentanil-midazolam versus sevoflurane anaesthesia in medetomidine pre-medicated Himalayan rabbits undergoing ovariohysterectomy

ObjectiveTo compare physiological effects of sufentanil-midazolam with sevoflurane for surgical anaesthesia in medetomidine premedicated rabbits. Study designProspective, randomized controlled experimental study. AnimalsEighteen female Himalayan rabbits, weight 2.1 ± 0.1 kg. MethodsPremedication with 0.1 mg kg−1 medetomidine and 5 mg kg−1 carprofen subcutaneously, was followed by intravenous anaesthetic induction with sufentanil (2.3 μg mL−1) and midazolam (0.45 mg mL−1). After endotracheal intubation, anaesthesia was maintained with sufentanil-midazolam (n = 9) or sevoflurane (n = 9). Ovariohysterectomy was performed. Intermittent positive pressure ventilation was performed as required. Physiological variables were studied perioperatively. Group means of physiologic data were generated for different anaesthetic periods. Data were compared for changes from sedation, and between groups by anova. Post-operatively, 0.05 mg kg−1 buprenorphine was administered once and 5 mg kg−1 carprofen once daily for 2–3 days. Rabbits were examined and weighed daily until one week after surgery. ResultsSmooth induction of anaesthesia was achieved within 5 minutes. Sufentanil and midazolam doses were 0.5 μg kg−1 and 0.1 mg kg−1, during induction and 3.9 μg kg−1 hour−1 and 0.8 mg kg−1 hour−1 during surgery, respectively. End-tidal sevoflurane concentration was 2.1% during surgery. Assisted ventilation was required in nine rabbits receiving sufentanil-midazolam and four receiving sevoflurane. There were no differences between groups in physiologic data other than arterial carbon dioxide. In rabbits receiving sevoflurane, mean arterial pressure decreased pre-surgical intervention, heart rate increased 25% during and after surgery and body weight decreased 4% post-operatively. Post-operative problems sometimes resulted from catheterization of the ear artery. ConclusionSevoflurane and sufentanil-midazolam provided surgical anaesthesia of similar quality. Arterial blood pressure was sustained during sufentanil-midazolam anaesthesia and rabbits receiving sevoflurane lost body weight following ovariohysterectomy. Mechanical ventilation was required with both anaesthetic regimens. Clinical relevanceAnaesthesia with sufentanil-midazolam in medetomidine premedicated healthy rabbits is useful in the clinical and the research setting, as an alternative to sevoflurane.

Induction of thioredoxin-1 in response to oxidative stress in dogs

To determine whether thioredoxin (TRX)-1 can be used as a valid biomarker for oxidative stress in dogs. ANIMALS AND SAMPLES: 10 Beagles and Madin-Darby canine kidney cells. Madin-Darby canine kidney cells were used to verify antigen cross-reactivity between human and canine anti-TRX-antibodies. Dogs were assigned to receive 21% or 100% O2 (5 dogs/group) via an artificial respirator during a 3-hour period of isoflurane anesthesia (starting at 0 hours). Blood and urine samples were collected before (baseline) and at 6, 12, 24, and 48 hours after commencement of inhalation anesthesia. Concentrations of TRX-1 and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in plasma and urine samples were analyzed; urine concentrations were reported as ratios against urine creatinine concentration. Canine TRX-1 was recognized by monoclonal human anti-TRX-1 antibodies (clones of adult T-cell leukemia-derived factor [ADF]-11 and ADF21) by western blot analysis. Results of an ELISA indicated that plasma TRX-1 concentration and urine TRX-1-to-creatinine concentration ratio increased rapidly after the 3-hour period of hyperoxia with maximal peaks at 12 and 6 hours, respectively. Urine 8-OHdG-to-creatinine concentration ratio also increased significantly after hyperoxia induction. However, unlike the rapid increase in urine TRX-1-to-creatinine concentration ratio, maximal urine 8-OHdG-to-creatinine concentration ratio was attained at 48 hours after hyperoxia induction. These variables remained unchanged from baseline in the control group. Results indicated that human anti-TRX monoclonal antibodies cross-reacted with canine TRX, and plasma TRX-1 concentrations were rapidly increased in dogs following an oxidative stress challenge. Thus, TRX may be a valuable clinical biomarker for detecting oxidative stress more rapidly than 8-OHdG in dogs.