Discontinuation Of Anesthesia Research Articles

Application of Laryngeal Mask Airway (LMA) in Medium and Short Period Traumatic Orthopedic Surgeries

Objective:Application of Laryngeal Mask Airway (LMA) as a ventilation method has been rarely explored in short and medium period orthopedic operations. In this study, we evaluated ventilatory efficacy of LMA in patients admitted to Ho Chi Minh City Orthopedic and Rehabilitation Hospital, Vietnam via a number of patient indicators including changes of pulse, blood pressure, airway pressure, SpO2 and pressure of CO2 at the end of an exhaled breath (EtCO2).
 Method: A total of 154 emergency and elective surgery cases with anesthesia were selected for the study.
 Result: One minute after LMA insertion to discontinuation of anesthetic, we recorded slower pulse of patients but only twenty-six cases (16.9%) required intravenous administration of atropine. Blood pressure of patients dropped after 1 minute following LMA insertion but then recovered afterward and only nine cases (5.8%) needed administration of ephedrine.
 Conclusion: After surgery, only eleven (7.15%) patients experienced oral mucosal bleeding but no further special treatment was used.
 Bangladesh Journal of Medical Science Vol. 23 No. 01 January’24 Page : 207-213

Is assessment of skeletal muscle mass useful to predict time-to-awake in awake craniotomies?

Awake craniotomy is the gold standard for the resection of brain lesions near eloquent areas. For the commonly used asleep-awake-asleep technique, the patient must be awake and fully cooperative as soon as possible after discontinuation of anesthetics. A shorter emergence time is essential to decrease the likelihood of adverse events. Previous research found no relationship between body mass index (BMI) and time-to-awake for intravenous anesthesia with propofol, which is a lipophilic agent. As BMI cannot differentiate between fat and muscle tissue, we hypothesize that skeletal muscle mass, particularly when combined with BMI, may better predict time-to-awake from propofol sedation. We aimed to evaluate the relationship between skeletal muscle mass and the time-to-awake in patients undergoing awake craniotomy, as well as the interaction between skeletal muscle mass and BMI. In 260 patients undergoing an awake craniotomy, we used preoperative magnetic resonance imaging to assess temporalis muscle and cross-sectional skeletal muscle area of the masseter muscles and at level of the third cervical vertebra. Time-to-awake was dichotomized as ≤20 and >20 minutes. No association between various measures of skeletal muscle mass and time-to-awake was observed, and no interaction between skeletal muscle mass and BMI was found (all P > .05). Likewise, patients with a high BMI and low skeletal muscle mass (indicating an increased proportion of fat tissue) did not have a prolonged time-to-awake. Skeletal muscle mass did not predict time-to-awake in patients undergoing awake craniotomy, neither in isolation nor in combination with a high BMI.

Predictors for delayed awakening in adult glioma patients receiving awake craniotomy under monitored anesthesia care

PurposeDelayed awakening after anesthetic discontinuation during awake craniotomy is associated with somnolence during functional brain mapping. However, predictors of delayed awakening in patients receiving monitored anesthesia care for awake craniotomy are unknown.MethodsThis retrospective cohort study analyzed 117 adult patients with supratentorial glioma in or near eloquent areas who received monitored anesthesia care for awake craniotomy between July 2020 and January 2023 at Linkou Chang Gung Memorial Hospital. These patients were divided into two groups according to their time to awakening (ability to speak their names) after propofol cessation: longer or shorter than 20 min (median duration). Because propofol was solely used anesthetic from skin incision to dural opening, parameters in Schnider model for propofol target-controlled infusion, such as age, sex, and BMI, were adjusted or propensity-matched to compare their anesthetic, surgical, and histopathological profiles.ResultsAfter propensity-matched comparisons of age and BMI, significant predictors of delayed awakening included IDH1 wild-type tumors and repeated craniotomies. Subgroup analysis revealed that older age and larger T2 volume were predictors in patients undergoing the first craniotomy, while lower preoperative Karnofsky performance scale scores and depression were predictors in repeated craniotomy cases. Delayed awakening was also associated with somnolence and a lower gross total resection rate.ConclusionOur retrospective analysis of patients receiving monitored anesthesia care for awake craniotomy revealed that delayed awakening after propofol discontinuation occurred more often in patients with IDH1 wild-type tumors and repeated craniotomies. Also, delayed awakening was associated with somnolence during functional mapping and a lower gross total resection rate.

Effects of Alfaxalone on the Induction and Maintenance of Total Intravenous Anesthesia in Gentoo Penguins (Pygoscelis papua).

Systemic anesthesia in penguins is often achieved using inhalation anesthetic agents alone, and information on injectable drugs for systemic anesthesia is limited. General anesthesia with a minimal effect on circulatory dynamics is necessary to perform noninvasive examinations and treatments in animals, including penguins. In this study, alfaxalone (ALFX), an injectable anesthetic agent, was examined to establish the optimal anesthetic method for gentoo penguins (Pygoscelis papua). Alfaxalone was administered intravenously through the metatarsal vein, and anesthesia was maintained by a constant rate infusion (CRI). A biological monitor was used to record numerous clinical indices, and the anesthetic depth was evaluated every 5 minutes during anesthesia; the CRI was adjusted until the optimal anesthetic depth was obtained. Anesthesia depth was assessed, and the CRI rate was adjusted. The CRI was stopped, and the time until recovery was recorded. Blood samples were collected to analyze plasma concentrations of ALFX. The mean total dose of ALFX required for anesthetic induction was 9 ± 1.9 mg/kg, the intubation time was 126 ± 21 seconds, and the maintenance infusion rate of ALFX was 0.3 ± 0.08 mg/kg/min. The time from discontinuation of anesthesia to extubation was 42 ± 23 minutes, and the time to recovery was 90 ± 33 minutes. Significant changes in the heart rate and blood pressure were not observed during the anesthetic events. The plasma concentration of ALFX under stable anesthesia was 6734 ± 4386 ng/mL (range, 3315-14 326 ng/mL). Although anesthesia using ALFX tended to result in a prolonged time to recovery in gentoo penguins, rapid induction of anesthesia and stable hemodynamics during anesthetic maintenance were achieved. Therefore, ALFX may be considered a suitable anesthetic method for noninvasive examinations and treatments in penguins.

Effects of Intraoperative Electro-acupuncture on Healthy Dogs Undergoing Anesthesia for Elective Procedures: A Randomized, Controlled, Blinded Clinical Trial

The objective of this study was to evaluate the efficacy of intraoperative electro-acupuncture (EAP) on duration of anesthetic recovery, immediate postoperative pain and isoflurane use in healthy dogs undergoing elective surgical procedures. Twenty-nine healthy dogs admitted for elective ovariohysterectomy or orchiectomy were enrolled and randomly assigned to either the EAP (n = 14) or control (n = 15) study groups. Subjects in the EAP Group were intubated and moved into the surgery suite. Acupuncture needles were then placed at LIV-13, ST-36 and GB-34 bilaterally with EAP started and maintained (at 20 Hz) for 20 minutes during the surgical procedure. Subjects in the Control Group did not receive any treatment after being moved into the surgery suite. Outcome data included time to extubation after the discontinuation of gas anesthesia, postoperative pain score (1 hour, 2 hours) and isoflurane concentration. The EAP Group had a significantly shorter anesthetic recovery time (mean±SD = 5.93 ±2.81 minutes) when compared to the Control Group (8.87 ±2.75 minutes; p = 0.007). Mean postoperative pain scores were nonsignificantly lower with EAP treatment at 1 hour (1.5±1.5, -25%) and 2 hours (1.82 ±2.0, -22%) when compared to control means (2.0 ±3.1 at 1 hour, 2.3±3.4 at 2 hours). There was no statistical difference between groups for isoflurane use. The study concluded that performing intraoperative EAP could shorten the time between discontinuation of gas anesthesia to extubation in healthy dogs undergoing an elective surgical procedure. Larger scale trials are warranted to validate the findings of this study and other potential benefits such as improved analgesia.

Continuous field flooding versus final one-shot CO2 insufflation in minimally invasive mitral valve repair

BackgroundInsufflation of carbon dioxide (CO2) into the operative field to prevent cerebral or myocardial damage by air embolism is a well known strategy in open-heart surgery. However, here is no general consensus on the best delivery approach.MethodsFrom January 2018 to November 2021, we retrospectively collected data of one hundred consecutive patients undergoing minimally invasive mitral valve repair (MIMVR). Of these, fifty patients were insufflated with continuous CO2 1 min before opening the left atrium and ended after its closure, and fifty patients were insufflated with one shot CO2 10 min before the start of left atrium closure. The primary outcome of the study was the incidence of transient post-operative cognitive disorder, in particular agitation and delirium at discontinuation of anesthesia, mechanical ventilation (MV) duration and intensive care unit (ICU) length of stay.ResultsIn all patients that received continuous field flooding CO2, correction of ventilation for hypercapnia during cardiopulmonary bypass (CPB) was applied with an increase of mean sweep gas air (2.5 L) and monitoring of VCO2 changes. One patient vs. 9 patients of control group reported agitation at discontinuation of anesthesia (p = 0.022). MV duration was 14 ± 3 h vs. 27 ± 4 h (p = 0.016) and ICU length of stay was 33 ± 4 h vs. 42 ± 5 h (p = 0.029). A significant difference was found in the median number of total micro-emboli recorded from release of cross-clamp until 20 min after end of CPB (154 in the continuous CO2 group vs. 261 in the one-shot CO2 control group; p < 0.001). Total micro-emboli from the first 15 min after the release of cross-clamp was 113 in the continuous CO2 group vs. 310 in the control group (p < 0.001). In the continuous CO2 group, the median number of detectable micro-emboli after CPB fell to zero 9 ± 5 min after CPB vs. 19 ± 3 min in the control group (p = 0.85).ConclusionContinuous field flooding insufflation of CO2 in MIMVR is associated with a lower incidence of micro-emboli and of agitation at discontinuation of anesthesia, along with improved MV duration and ICU length of stay.

Effect of Flumazenil on Emergence Agitation after Orthognathic Surgery: A Randomized Controlled Trial.

Flumazenil, a gamma-aminobutyric acid receptor antagonist, can promote arousal even under general anesthesia without the use of benzodiazepines. We hypothesized that flumazenil could promote arousal and reduce emergence agitation in patients undergoing orthognathic surgery with sevoflurane anesthesia. One hundred and two patients were randomly allocated to the control or flumazenil group. Saline or flumazenil was administered at the end of the surgery. The incidence of emergence agitation was measured by using Aono’s four-point scale, with scores of 3 and 4 indicating emergence agitation. The primary outcome was the incidence of emergence agitation. Secondary outcomes included duration of emergence agitation and time intervals between the discontinuation of anesthetics, first response, extubation, and post-anesthesia care-unit discharge readiness. The incidence of emergence agitation was 58.3% and 38.9% in the control and flumazenil groups, respectively, but it was not statistically significant. However, the duration of emergence agitation was shorter in the flumazenil group (p = 0.012). There were no significant differences in the time intervals between the discontinuation of anesthetics, first response, and extubation. Although flumazenil did not reduce the incidence of emergence agitation in patients undergoing orthognathic surgery with sevoflurane anesthesia, it can be considered as an option for awakening patients in terms of improving emergence profiles.

The effects of pre-emptive intravenous ibuprofen on the thiol/disulfide homeostasis and C-reactive protein level as the markers of oxidative stress and inflammation during gynecologic laparoscopy: A randomised clinical trial.

In this study, we aimed to investigate the anti-inflammatory and antioxidant effects of intravenous ibuprofen by using the C-reactive protein level and thiol/disulfide homeostasis as the oxidative stress marker. This study was conducted on 70 patients aged between 30 and 65 who were scheduled for elective laparoscopic hysterectomy. The patients were divided into two groups to receive either pre-emptive 800mg of intravenous ibuprofen plus 1000mg of intravenous paracetamol (Group IP) or only 1000mg of intravenous paracetamol as a control group (Group P). The blood samples for thiol/disulfide homeostasis were collected as follows: before induction of anesthesia (T0), before pneumoperitoneum (T1), following postdeflation and discontinuation of anesthesia (T2), and postoperative 24th hour (T3). Simultaneous blood samples for C-reactive protein (CRP) were also collected. The pre- and postoperative urea, creatinine, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels were measured. A total of 69 patients were included in the study. The patient's characteristics and intraoperative variables were comparable between groups (P>.05). The number of patients requiring rescue analgesia, the total amount of analgesic used, Visual Analog Scale (VAS) scores, and postoperative side effects were significantly lower in Group IP (P<.001). The decrease in native and total thiol levels at T1, T2, and T3 measurement points was significant in Group IP (P<.001). In both groups, the comparison to baseline values demonstrated no significant changes in terms of disulfide level (P>.05). The simultaneous CRP levels indicated a significant increase at the postoperative 24hour in both groups (P<.001). The difference between groups was insignificant (P>.05). There was a significant increase in urea and creatinine levels in patients of Group IP (P<.05). The pre-emptive administration of ibuprofen provided effective pain control after gynecologic laparoscopy. However, ibuprofen changed the thiol/disulfide homeostasis in favor of oxidation and had no beneficial effect in surgically induced oxidative stress.

The Relationship between the Timing of Sugammadex Administration and the Upper Airway Obstruction during Awakening from Anesthesia: A Retrospective Study.

Background and Objectives: The harmonization of recovery of consciousness and muscular function is important in emergence from anesthesia. Even if muscular function is recovered, tracheal extubation without adequate recovery of consciousness may increase the risk of respiratory complications. In particular, upper airway obstruction is one of the common respiratory complications and can sometimes be fatal. However, the association between the timing of sugammadex administration and the upper airway obstruction that can occur during awakening from anesthesia has rarely been studied. Materials and Methods: The medical records of 456 patients who had surgery under general endotracheal anesthesia (GETA) at the Haeundae Paik Hospital between October 2017 and July 2018 and who received intravenous sugammadex to reverse rocuronium-induced neuromuscular blockade were analyzed. The correlations between bispectral index (BIS) and minimum alveolar concentration (MAC) at the time of sugammadex administration, the incidence of complications, and the time to tracheal extubation were analyzed to investigate how different timings of sugammadex administration affected upper airway obstruction after tracheal extubation. Conclusions: The effect of BIS and the duration from anesthetic discontinuation to sugammadex administration on upper airway obstruction was not statistically significant. However, the odds ratio of complication rates with MAC < 0.3 compared with MAC ≥ 0.3 was 0.40 (95% confidence interval 0.20 to 0.81, p = 0.011), showing a statistically significant increase in risk with MAC ≥ 0.3 for upper airway obstruction.

Effects of Dexmedetomidine and Fentanyl Premedication on Quality of Extubation in Children undergoing Tonsillectomy: A Prospective Cohort Study

Introduction: Smooth extubation in children is a challenging task, especially those undergoing tonsillectomy. Dexmedetomidine, an alpha-2 receptor agonist has been found to be beneficial in paediatric anaesthesia due to its anxiolytic, sedative and analgesic properties. It also attenuates haemodynamic stress response and airway reflexes to intubation and extubation. Fentanyl, a synthetic opioid is also extensively used in paediatric anaesthesia. Aim: To compare the effects of dexmedetomidine and fentanyl premedication on quality of extubation and extubation haemodynamics. Materials and Methods: The prospective cohort study was conducted in 120 children divided into two groups of 60 each, aged 5-12 years, belonging to American Society of Anaesthesiologists’ (ASA) physical status I and II, posted for elective tonsillectomy under general anaesthesia. Group F received fentanyl 2 μg/kg intravenously and group D, dexmedetomidine 0.5 μg/kg as intravenous infusion over 10 minutes as premedication. The time from discontinuation of anaesthetics to extubation and to opening the eyes in response to verbal stimuli were noted. The quality of extubation was evaluated according to the 5 point extubation score and postoperative sedation assessed using Ramsay sedation score. The haemodynamic parameters were monitored immediately after discontinuation of anaesthetics and at 1, 3, 5 and 10 minutes postextubation. Any complications like airway obstruction, bradycardia, and hypotension were noted and treated appropriately. Statistical Package for Social Sciences (SPSS) software version 22 was used for statistical analysis and categorical outcomes compared with Chi-square test/Fisher’s-Exact test. Results: Extubation was smoother in group receiving dexmedetomidine. The median time from discontinuation of anaesthetics to extubation and eye opening was significantly shorter in dexmedetomidine group compared to fentanyl group (p&lt;0.001). Postoperative sedation score was comparable between the two groups. Heart Rate (HR) and Mean Arterial Pressure (MAP) monitored showed significantly stable values in the dexmedetomidine group (p&lt;0.001) when compared to fentanyl soon after discontinuation of anaesthetics and 1, 3, 5 and 10 minutes postextubation. Conclusion: Premedication with dexmedetomidine 0.5 μg/kg intravenously provides better quality and haemodynamics of extubation compared to fentanyl 2 μg/kg in children undergoing tonsillectomy, without causing significant sedation.

Effect of pregabalin versus midazolam premedication on the anesthetic and analgesic requirements in pediatric day-case surgery: A randomized controlled trial

ABSTRACT Background: This study aimed to compare pregabalin and midazolam premedication in pediatric day-case surgery regarding anesthetic and analgesic requirements.Methods: Sixty patients scheduled for day-case surgery were randomly premedicated orally with either pregabalin (Group P) or midazolam (Group M). Intraoperative anesthetic and analgesic requirements were assessed as primary outcomes. Modified Ramsay Sedation Score (RSS), hemodynamic variables, time to eye opening and time to extubation after discontinuation of general anesthesia were measured. Post-anesthesia care unit (PACU) duration of stay, postoperative Pediatric Anesthesia Emergence Delirium (PAED) scale, and Faces Legs Activity Cry Consolability (FLACC) scale, and post-operative analgesic requirements were assessed as secondary outcomes. The study was pre-registered at the Pan African Clinical Trials Registry (registration number: PACTR201907535888819; date of registration: 22/07/2019).Results: We found no significant differences between the studied groups regarding types and duration of surgery, preoperative modified RSS, and postoperative PAED. The mean ranks of sevoflurane and fentanyl consumptions were significantly lower in group P (p < 0.001). Patients in group P showed significantly lower means of heart rate and arterial blood pressure after induction of anesthesia. Postoperative FLACC pain score showed a significantly lower mean rank in group P. The need for rescue analgesics and the mean ranks of rectal diclofenac and meperidine consumption was significantly lower in group P (p < 0.001). The mean ranks of total paracetamol doses were comparable in both groups (p = 0.090). Group P showed a significantly lower duration of stay in PACU and time to open the eye and to extubate, but significantly higher time to first analgesic requirement.Conclusion: Pregabalin significantly reduced the perioperative anesthetic and analgesic requirements, the PACU duration of stay, and the time to open the eye and to extubate, in comparison to midazolam; therefore, its use as a premedication in pediatric day-case surgery is recommended.

Carbon dioxide narcosis due to human error in a dog

Incorrect assembly of a parallel Lack (Mapleson A) breathing system resulted in carbon dioxide narcosis in a dog due to rebreathing of expiratory gases. A seven-year-old, male neutered Rottweiler, weighing 49 kg, failed to recover after discontinuation of inhalational anaesthesia following a forequarter amputation for osteosarcoma. During recovery, the endotracheal tube had been connected to a parallel Lack anaesthetic breathing system delivering 100 per cent oxygen at 5 l/minute. Although a prolonged recovery, 30 minutes, all vital parameters were considered within normal limits until a severe increase in respiratory effort was noted. Capnography revealed rebreathing with an end-tidal carbon dioxide tension of &gt;150 mm Hg (&gt;19.9 kPa). The dog was transferred to a circle breathing system, and with normalisation of the capnogram, recovery proceeded without further complications. Visual inspection of the parallel Lack breathing system revealed misassembly which had resulted in rebreathing of expiratory gases, extreme hypercapnia causing prolonged recovery due to narcosis.

Electrographic predictors of successful weaning from anaesthetics in refractory status epilepticus.

Intravenous third-line anaesthetic agents are typically titrated in refractory status epilepticus to achieve either seizure suppression or burst suppression on continuous EEG. However, the optimum treatment paradigm is unknown and little data exist to guide the withdrawal of anaesthetics in refractory status epilepticus. Premature withdrawal of anaesthetics risks the recurrence of seizures, whereas the prolonged use of anaesthetics increases the risk of treatment-associated adverse effects. This study sought to measure the accuracy of features of EEG activity during anaesthetic weaning in refractory status epilepticus as predictors of successful weaning from intravenous anaesthetics. We prespecified a successful anaesthetic wean as the discontinuation of intravenous anaesthesia without developing recurrent status epilepticus, and a wean failure as either recurrent status epilepticus or the resumption of anaesthesia for the purpose of treating an EEG pattern concerning for incipient status epilepticus. We evaluated two types of features as predictors of successful weaning: spectral components of the EEG signal, and spatial-correlation-based measures of functional connectivity. The results of these analyses were used to train a classifier to predict wean outcome. Forty-seven consecutive anaesthetic weans (23 successes, 24 failures) were identified from a single-centre cohort of patients admitted with refractory status epilepticus from 2016 to 2019. Spectral components of the EEG revealed no significant differences between successful and unsuccessful weans. Analysis of functional connectivity measures revealed that successful anaesthetic weans were characterized by the emergence of larger, more densely connected, and more highly clustered spatial functional networks, yielding 75.5% (95% confidence interval: 73.1-77.8%) testing accuracy in a bootstrap analysis using a hold-out sample of 20% of data for testing and 74.6% (95% confidence interval 73.2-75.9%) testing accuracy in a secondary external validation cohort, with an area under the curve of 83.3%. Distinct signatures in the spatial networks of functional connectivity emerge during successful anaesthetic liberation in status epilepticus; these findings are absent in patients with anaesthetic wean failure. Identifying features that emerge during successful anaesthetic weaning may allow faster and more successful anaesthetic liberation after refractory status epilepticus.

Titration of sevoflurane anesthesia to optimize the time to regain airway reflexes in patients undergoing elective surgery: A randomized clinical trial comparing desflurane and sevoflurane anesthesia

Desflurane has adverse environmental effects, but has clinical advantages to speed emergence and return of protective airway reflexes compared with sevoflurane. We hypothesized that weaning of the inspired sevoflurane during the final 15minutes of surgery would eliminate differences in airway reflex recovery between these agents. After obtaining IRB approval and informed consent, 40 patients undergoing elective surgery (≥1-hour) randomly received desflurane or sevoflurane. Patients swallowed 20mL of water without drooling or coughing, and then received sedation and PONV pre-medication. Anesthesia was induced using propofol and fentanyl and maintained with desflurane or sevoflurane through a laryngeal mask airway maintaining a bispectral index of 45-50 and 50-60 during the final 15minutes before surgery end. Cardiorespiratory variables and age-adjusted minimal alveolar concentration were recorded. The duration between anesthetic discontinuation and first appropriate response to command was measured; the laryngeal mask airway was removed. Two minutes after responding to command, patients were positioned semi-upright and attempted to swallow water. If successful swallowing was not achieved, the test was repeated every 4minutes after each failure until successful swallowing was achieved. Average anesthetic concentration and bispectral index was similar in patients receiving desflurane vs sevoflurane. Response times after discontinuation of anesthetics were similar. There were no differences in the recovery of swallowing ability between desflurane and sevoflurane groups. Weaning of sevoflurane during the final 15 minutes of surgery eliminates clinical advantages of the more rapid return of airway reflexes with desflurane.

Perseus A500 enables faster recovery from desflurane general anesthesia.

The Dräger Perseus A500 (Perseus) anesthetic workstation has been designed with a lower internal volume. We evaluated the recovery time following general anesthesia using the Perseus workstation compared with that using the conventional Dräger Fabius Plus workstation. Following approval by our institutional research ethics committee, 50 patients receiving elective surgery under general anesthesia were enrolled in the study. Written informed consent was obtained from each patient. The patients were divided into the Perseus group and a control group. The Perseus anesthesia workstation was used for the Perseus group, and the Fabius Plus was used for the control group. General anesthesia was maintained with a 4.2% end-tidal concentration of desflurane, remifentanil, fentanyl, and regional anesthesia. After the surgical procedure, the administration of desflurane was discontinued. The inspiratory and expiratory desflurane concentration, time taken for patients to open their eyes, and the time taken to extubate the trachea after discontinuation of anesthetics were recorded. The inspiratory and expiratory desflurane concentration after the administration of desflurane was discontinued was lower in the Perseus group. Moreover, the time taken for patients to open their eyes was statistically significantly quicker in the Perseus group when compared with the control group: 284 ± 60 vs 325 ± 43s, respectively. The time taken for extubation was also statistically significantly quicker in the Perseus group when compared with the control group: 350 ± 67 vs 388 ± 62s, respectively. We demonstrate in this study that Perseus enables the faster wash-out of anesthetics and faster recovery of patients after general anesthesia.

Clinical measurements performed during alfaxalone total intravenous anaesthesia for radiography and neurophysiological investigations in dogs

ObjectiveTo describe clinically relevant, physiological measurements collected during a 3 hour duration of alfaxalone total intravenous anaesthesia. Study designCase series. AnimalsA total of 112 client-owned middle-aged or older dogs. MethodsDogs were premedicated with intramuscular acepromazine (0.03 mg kg–1). Anaesthesia was induced and subsequently maintained for up to 3 hours with alfaxalone administered intravenously. Dogs breathed 100% oxygen via an endotracheal tube. Heart rate, respiratory rate and blood pressure were evaluated 30 minutes after administration of acepromazine and used as baseline values for comparisons of intra-anaesthetic data. Blood glucose was measured 1 week prior to anaesthesia and every hour during alfaxalone anaesthesia. Quality and duration of recovery were recorded. Mean data for physiological variables were compared over three time points—before induction of anaesthesia, for the first hour of anaesthesia and from 60 minutes to discontinuation of anaesthesia. ResultsMean induction dose of alfaxalone was 1.4 mg kg–1 [95% confidence interval (CI) 1.3–1.5). Post induction apnoea for >60 seconds occurred in 13 (11.6%) dogs. Mean alfaxalone infusion rate during the first 60 minutes of anaesthesia was 0.099 mg kg–1 minute–1; mean infusion rate was 0.092 mg kg–1 minute–1 from 60 minutes until discontinuation of anaesthesia. Heart rate was well maintained; hypotension (mean arterial blood pressure < 60 mmHg) was encountered in 23 (21%) dogs. Blood glucose levels did not alter during anaesthesia. Median time between discontinuation of alfaxalone infusion and extubation was 17 (7–35 minutes), time to assuming sternal recumbency was 75 (58–110 minutes), and time to standing was 109 (88–140 minutes). Conclusions and clinical relevanceAlfaxalone infusion provided effective anaesthesia in this population. In a minority of cases, respiratory and haemodynamic support of the patient was required.

Impact of intracranial hypertension on the short-term prognosis in dogs undergoing brain tumor surgery.

The present study used data from anesthetic records to analyze variables of intracranial pressure (ICP) during brain tumor surgery or in the early postoperative period as prognostic indicators in dogs. Data from 17 dogs which were scheduled to undergo elective craniotomy for brain tumor surgery from 2009 to 2012 were included. Of these, five (29.4%) died during 14 days after the surgery because of respiratory failure following pneumonia (n=2), euthanasia due to difficulty in treatment of status epilepticus (n=1), tumor-bed hematoma (n=1), and unknown reason (n=1). In the 12 surviving dogs, neurological signs were improved or resolved at discharge. All dogs were administered midazolam and droperidol-fentanyl as premedication. General anesthesia was induced using propofol maintained on isoflurane and oxygen. Direct ICP was obtained via a Codman Microsensor strain gauge transducer. ICP hypertension (>13 mmHg) measured after 15 min of recovery from the moment after discontinuation of anesthesia by turning off the vaporizer dial was associated with poor prognosis (odds ratio, 20.00; 95% confidence interval, 1.39−287.60, P=0.028). This suggests that intracranial pressure influences the postoperative mortality rate in dogs undergoing brain tumor surgery.

Comparison of transdermal fentanyl and oral tramadol for lateral thoracotomy in dogs: cardiovascular and behavioural data

ObjectiveTo compare the analgesic efficacy and suitability of an existing oral tramadol-based protocol with a transdermal fentanyl-based protocol following lateral thoracotomy in dogs. Study designProspective randomized clinical trial. AnimalsA group of 16 healthy laboratory beagle dogs. MethodsDogs were randomly allocated to one of two treatment groups: group F (intramuscular methadone 0.2 mg kg–1 and transdermal fentanyl 2.6 mg kg–1 both administered on discontinuation of anaesthesia, n = 8) or group T (intramuscular methadone 0.2 mg kg–1 on discontinuation of anaesthesia and again 4 hours later, followed by oral tramadol 12 mg kg–1 per 24 hours commencing 7 hours after discontinuation of anaesthesia, n = 8). Intercostal bupivacaine (0.5–1 mg kg–1) and subcutaneous carprofen (4 mg kg–1) were administered to all dogs at induction. Body weight (BW), presence of clinical signs, pain score, activity, heart rate (HR) and mean arterial pressure (MAP) were assessed for 72 hours postoperatively. ResultsNo significant differences were observed in BW change, presence of clinical signs or gross locomotor activity between groups. Pain scores were low at all times for all dogs, and rescue analgesia was not required. Dogs in group T exhibited higher pedometric activity (p = 0.006), HR (p < 0.001) and MAP (p < 0.001) than those in group F, in particular on night 1 following surgery. Least squared mean (LSM) pedometric activity was 1.81 and 1.02 jerks minute–1, LSM HR was 111.13 and 78.64 beats minute–1 and LSM MAP was 111.62 and 105.24 mmHg, respectively, in groups T and F. Conclusions and clinical relevanceBoth regimes appear to provide adequate analgesia following lateral thoracotomy in dogs. Ease of administration of transdermal fentanyl compared to oral tramadol is advantageous. Reduced activity observed with the fentanyl regime was not associated with any adverse effects and may be desirable following some invasive surgeries. However, while transdermal fentanyl remains currently unavailable in the European Union, the oral tramadol-based regime provides an acceptable alternative.

Refinement of embolic stroke model in rats: Effect of post-embolization anesthesia duration on arterial blood pressure, cerebral edema and mortality

BackgroundInjection of a clot into the internal carotid artery is an experimental model of ischemic stroke that is considered to closely mimic embolic stroke in humans. In this model, the common carotid artery typically remains temporarily occluded to permit time for stabilization of the clot in the middle cerebral artery. However, the associated lengthening of the anesthesia duration could affect arterial blood pressure and stroke outcome. New methodWe refined the model by examining how increasing isoflurane anesthesia duration from 30 to 60 min after clot embolization affects mortality, infarct volume, edema, blood-brain barrier permeability, and the 8-h post-ischemic time course of blood pressure, which has not been reported previously in this model. ResultsWe found that arterial pressure increased after discontinuing anesthesia in both embolized groups and that the increase was greater than in the corresponding non-embolized sham-operated rats. At 24 h, the group with 60-min post-ischemia anesthesia exhibited greater brain water content and a greater ipsilateral-to-contralateral ratio of extravasated Evans blue dye. Mortality was greater in the 60-min group, but infarct volume among survivors was not different from that in the 30-min anesthesia group. Comparison with existing methodsThis study refines the embolic stroke model by demonstrating the importance of minimizing the duration of anesthesia after embolization. ConclusionsThese data indicate that early discontinuation of isoflurane anesthesia after clot embolization permits an earlier hypertensive response that limits edema formation and mortality without significantly affecting infarct volume in survivors, thereby decreasing the required number of animals.

Effective Postoperative Analgesia Using Intravenous Flurbiprofen and Acetaminophen

Management of postoperative pain is one of the most important components in postoperative care, because most patients have pain after dental surgery. The aim of this study was to evaluate whether acetaminophen could be an alternative to fentanyl in combination with a nonsteroidal anti-inflammatory drug (NSAID) as an analgesic after dental surgery in cases in which narcotic drugs were contraindicated. Patients were 24- to 54-year-old men who underwent enucleation of a mandibular cyst under general anesthesia. The authors measured time from discontinuation of anesthetic administration until discharge from the operating room and postoperative pain during 4hours after discharge. They compared these parameters between patients who were intravenously administered an NSAID such as flurbiprofen with fentanyl (NSAID/fentanyl group) and those administered an NSAID with acetaminophen (NSAID/acetaminophen group). Parametric data of time were analyzed using Student t test. Nonparametric data of the analgesic effect were analyzed using Mann-Whitney U test. Time until discharge from the operating room after discontinuation of anesthetics in the NSAID/fentanyl group was significantly longer than that in the NSAID/acetaminophen group (P<.05). In contrast, there was no significant difference in analgesic effect between the NSAID/acetaminophen and NSAID/fentanyl groups (P>.05). Although recovery time in the operating room of the flurbiprofen and acetaminophen group was markedly shorter than that of the flurbiprofen and fentanyl group, the postoperative analgesic effects of the 2 drugs were equipotent. Therefore, acetaminophen can be an alternative to fentanyl in cases in which narcotic drugs are contraindicated.