Total intravenous anaesthesia in ponies using detomidine, ketamine and guaiphenesin: Pharmacokinetics, cardiopulmonary and endocrine effects

Pharmacokinetics and some pharmacological effects of anaesthesia induced by a combination of detomidine, ketamine and guaiphenesin were investigated in eight ponies. Cardiopulmonary function was studied and plasma met-enkephalin, dynorphin, β-endorphin; arginine vasopressin, adrenocorticotrophin, cortisol, 11-deoxycortisol and catecholamine concentrations were measured. The combination produced slight cardiorespiratory depression, hyperglycaemia and a reduction in haematocrit. There were no changes in plasma opioids, pituitary peptides or catecholamines. Plasma cortisol concentration decreased and plasma 11-deoxycortisol increased indicating a suppression of steroidogenesis. Steady state ketamine and guaiphenesin concentrations were attained during the infusion period, and ketamine concentrations likely to provide adequate analgesia for surgical operations were achieved (more than 2.2 μg ml-1). Steady state detomidine concentration was not attained. The ponies took on average 68 minutes to recover to standing and the recovery was uneventful.

Cardiorespiratory, endocrine and metabolic changes in ponies undergoing intravenous or inhalation anaesthesia

Six Welsh gelding ponies (weight 246 ± 6 kg) were premedicated with 0.03 mg/kg of acepromazine intravenously (i.v.) followed by 0.02 mg/kg of detomidine i.v. Anaesthesia was induced with 2 mg/kg of ketamine i.v. Ponies were intubated and lay in left lateral recumbency. On one occasion anaesthesia was maintained for 2 h using 1.2% halothane in oxygen. The same group of ponies were anaesthetized 1 month later using the same induction regime and anaesthesia was maintained with a combination of detomidine, ketamine and guaiphenesin, while the ponies breathed oxygen-enriched air. Electrocardiogram, heart rate, mean arterial blood pressure, cardiac output, respiratory rate, blood gases, temperature, haematocrit, glucose, lactate and cortisol were measured and cardiac index and systemic vascular resistance were calculated in both groups. Beta-endorphin, met-enkephalin, dynorphin, arginine vasopressin (AVP), adrenocorticotrophic hormone (ACTH) and catecholamines were measured in the halothane anaesthesia group only and 11-deoxycortisol during total intravenous anaesthesia (TIVA) only. Cardiorespiratory depression was more marked during halothane anaesthesia. Hyperglycaemia developed in both groups. Lactate and AVP increased during halothane anaesthesia. Cortisol increased during halothane and decreased during TIVA. There were no changes in the other hormones during anaesthesia. Recovery was smooth in both groups. TIVA produced better cardiorespiratory performance and suppressed the endocrine stress response observed during halothane anaesthesia.

Comparison of medetomidine-ketamine and dexmedetomidine-ketamine anesthesia in golden-headed lion tamarins

The cardiovascular, respiratory, and anesthetic effects of medetomidine-ketamine (20 μg/kg bodyweight [BW] and 10 mg/kg BW) (MK group) or dexmedetomidine-ketamine (10 μg/kg BW and 10 mg/kg BW) (DK group) were studied in golden-headed lion tamarins. Heart rate decreased after administration of both combinations; this reduction was statistically greater in the DK group than in the MK group after 15 and 45 minutes. Systolic arterial pressure decreased in a similar way in both groups, except at 15 minutes, when systolic arterial pressure was significantly lower in the DK group. Diastolic arterial pressure, mean arterial pressure, respiratory rate, and rectal temperature were progressively reduced in all groups. Sedation time was significantly shorter and anesthesia time was significantly longer in the DK group compared with MK group. Anesthetic quality and analgesia scores were significantly greater at 5 and 15 minutes in the DK group compared with the MK group. The administration of dexmedetomidine-ketamine is as safe and effective as the administration of medetomidine-ketamine in tamarins.

Effects of tiletamine/zolazepam-romifidine-atropine in ocelots (Leopardus pardalis)

Objectives: To evaluate the effects of a combination of tiletamine-zolazepam-romifidine-atropine in ocelots. Design: Prospective experimental trial. Animals: Eight captive adult ocelots (three females and five males). Methods: Calculated doses of tiletamine-zolazepam (3.75 mg kg -1), romifidine (50 μg kg-1) and atropine (0.04 mg kg-1) were administered intramuscularly. After immobilization, animals were weighed and the real doses determined. Heart rate, respiratory frequency, noninvasive systolic, diastolic, and mean arterial pressure, arterial oxygen hemoglobin saturation, and rectal temperature were measured. Data were analyzed by means of ANOVA for repeated measures, followed by the Tukey test to compare values over time. Results: Doses administered were 3.4 ± 0.6 mg kg-1 of tiletamine-zolazepam, 0.04 ± 7.0 mg kg-1 of romifidine, and 0.03 ± 0.007 mg kg-1 of atropine. The mean time to recumbency and duration of immobilization were 7.0 ± 4.5 and 109.2 ± 27.9 minutes, respectively. The median times to standing and walking were 52.3 [0-90] and 2.3 [0-69.3] minutes, respectively. A decrease in heart rate was observed 45 minutes following drug administration. Arterial blood pressure was maintained during the study. Conclusions and clinical relevance: This protocol produced good immobilization in ocelots with minimal changes over time in cardiovascular parameters.

Comparison of the effects of barbiturate, benzodiazepine and ketamine on visual evoked potentials in rabbits

The aim of this study was to compare the effects of barbiturate, benzodiazepine and ketamine on flash-evoked potentials (F-VEP) in adult rabbits. A total of 36 animals were studied, 16 after pentobarbital endovenous (EV) inffusion, 10 after midazolam EV administration, and 10 after ketamine EV inffusion. Pentobarbital induced triphasic F-VEP, first negative (N1), secondpositive (P1), third negative (N2) waves, all with large amplitudes and P1 with well-defined morphology. Mean P1 latency was 33ms. Midazolam induced similar but less defind triphasic waves, with mean latency of 27ms. Ketamine induced poliphasic and poorly defined F-VEP, with mean first positive (P1) latency of 27ms. Statistical analysis showed more elongated latency for the pentobarbital group than the midazolam and ketamine groups. The results of this study suggest that the pharmacological effects of pentobarbital and midazolam on GABA neurotransmission in rabbit visual cortex may be different; another neurotransmission system, possibly cholinergic, may be involved. The ketamine effect seen in rabbit visual cortex seems to be different from pentobarbital and midazolam.

Effects of constant rate infusion of anesthetic or analgesic drugs on general anesthesia with isoflurane: A retrospective study in 200 dogs

Constant rate infusion (CRI) shows several advantages in balanced anesthesia, such as reduction of requirement for inhaled anesthetics and control of pain. The most commonly used drugs in these protocols are local anesthetics, dissociative, and opioids, which may be administered alone or in combinations. We evaluated the records of 200 dogs that underwent various surgical procedures with anesthetic or analgesic CRI in the perioperative period during 2011 and 2012 at the Veterinary Hospital of Franca University (Unifran), and identified possible complications during the transoperative period. Records evaluated included clinical state, laboratory tests, drugs used in premedication and induction, and CRI protocol. Acepromazine and morphine were the main drugs used in premedication. Propofol was used to induce anesthesia alone or in combination with other agents. We evaluated records of the 25 different CRI protocols. Fentanyl was the main drug employed in CRI, either alone or in combination. There were 128 episodes of anesthetic complications during CRI;the most common were hypotension, hypertension, and tachycardia, which occurred in 43 (32%), 35 (26.3%), and 19 (14.2%) dogs, respectively. Cardiac arrhythmia was reported in only 4 dogs. Signs of respiratory depression were present in dogs treated with 6 different CRI protocols. The consumption of isoflurane (vol %) reduced between 15.7% and 21.05% after 30minutes of the CRI in the fentanyl and fentanyl-lidocaine-ketamine CRI groups (p<0.05). In conclusion, CRI is a valid component of balanced anesthesia in dogs, safe, and has a low incidence of adverse effects. However, future studies are warranted to describe the results of the clinical use of CRI to better characterize and refine this technique.

Cardiovascular response during trigeminal ganglion compression for trigeminal neuralgia according to the use of local anesthetics

There are controversies about the use of local anesthetics during balloon compression for trigeminal neuralgia (TN) as a protective factor for cardiovascular events. The objective of this study was to investigate cardiovascular parameters (blood pressure and heart rate [HR]) of patients that underwent trigeminal balloon compression with local anesthetics compared to a control group (placebo). This is a randomized controlled study; 55 patients were randomized into two groups: study (deep sedation and trigeminal block with 0.8-mL lidocaine 2%) and control group (deep sedation and trigeminal injection of 0.8-mL saline). Blood pressure and HR were measured in five distinct moments: preoperative, during puncture for local anesthesia/placebo, during puncture with the catheter, during balloon compression, and final evaluation. Statistical analysis was performed with Pearson`s chi (2) and McNemar tests and the analysis of variance for repetitive measures. The means of systolic and diastolic blood pressures (SBP and DBP, respectively) were higher in the control group when compared to the study group at the evaluation during puncture with the catheter (p < 0.001) and balloon compression (p < 0.001 and p = 0.018 for DBP and SBP, respectively). There was an increase in the HR in the control group during the procedure (p = 0.017). The use of local anesthetics during the trigeminal balloon compression for TN can have a preventive role for the risk of cardiovascular events.

Epidermal iontophoresis: II. Application of the ionic mobility-pore model to the transport of local anesthetics

Purpose, An in vitro study was carried out to determine the iontophoretic permeability of local anesthetics through human epidermis. The relationship between physicochemical structure and the permeability of these solutes was then examined using an ionic mobility-pore model developed to define quantitative relationships. Methods. The iontophoretic permeability of both ester-type anesthetics (procaine, butacaine, tetracaine) and amide-type anesthetics (prilocaine, mepivacaine, lidocaine, bupivacaine, etidocaine, cinchocaine) were determined through excised human epidermis over 2 hrs using a constant d.c. current and Ag/AgCl electrodes. Individual ion mobilities were determined from conductivity measurements in aqueous solutions. Multiple stepwise regression was applied to interrelate the iontophoretic permeability of the solutes with their physical properties to examine the appropriateness of the ionic mobility-pore model and to determine the best predictor of iontophoretic permeability of the local anesthetics. Results. The logarithm of the iontophoretic permeability coefficient (log PCj,iont) for local anesthetics was directly related to the log ionic mobility and MW for the free volume form of the model when other conditions are held constant. Multiple linear regressions confirmed that log PCj,iont was best defined by ionic mobility (and its determinants: conductivity, pK(a) and MW) and MW. Conclusions. Our results suggest that of the properties studied, the best predictors of iontophoretic transport of local anesthetics are ionic mobility (or pK(a)) and molecular size. These predictions are consistent with the ionic mobility pore model determined by the mobility of ions in the aqueous solution, the total current, epidermal permselectivity and other factors as defined by the model.

Comparison of Brazilian spiritist mediumship and dissociative identity disorder

We studied the similarities and differences between Brazilian Spiritistic mediums and North American dissociative identity disorder (DID) patients. Twenty-four mediums selected among different Spiritistic organizations in Sao Paulo, Brazil, were interviewed using the Dissociative Disorder Interview Schedule, and their responses were compared with those of DID patients described in the literature. The results from Spiritistic mediums were similar to published data on DID patients only with respect to female prevalence and high frequency of Schneiderian first-rank symptoms. As compared with individuals with DID, the mediums differed in having better social adjustment, lower prevalence of mental disorders, lower use of mental health services, no use of antipsychotics, and lower prevalence of histories of physical or sexual childhood abuse, sleepwalking, secondary features of DID, and symptoms of borderline personality. Thus, mediumship differed from DID in having better mental health and social adjustment, and a different clinical profile.

Influence of anesthetics on pharyngeal flap surgery: a 23-year study

This study assessed the influence of anesthetics on early complications after pharyngeal flap surgery. A 23-year retrospective chart review was carried out of all patients at the authors` institution who underwent superiorly based pharyngeal flap surgery. Variables analyzed were gender, age at the time of surgery, cleft type, anesthesia procedure used and complications in the early postoperative period. 2299 patients (50% male; 50% female) who underwent pharyngeal flap surgery between 1980 and 2003 were reviewed. The highest number of surgeries was performed in patients aged 11-20 years. There were 1042 patients with at least one type of complication. Of these, 39 required reoperation to control complications such as bleeding and airway obstruction. There were no records of death. Vomiting and pain were the most frequent postoperative complications (16% and 14% of patients, respectively). Lower complication rates were observed when anesthesia protocols included sevoflurane, propofol and opioids.

Schistosoma mansoni: effects of anesthetics and antimonial drugs on worm shift in the mouse

Mice experimentally infected with Schistosoma mansoni were injected with sodium thiopental or sodium antimonyl gluconate (Triostib R), or submitted to halothane inhalation, with or without a previous injection of thiopental. Data obtained showed that halothane and thiopental induce worm shift to the liver (99 and 76%, respectively). Sodium gluconate and antimonium (Triostib R) shifted 52% of worms towards the liver. These results seem to indicate that the use of antimonium would be unnecessary, when surgical removal of schistosomules is carried out through the extracorporeal filtration technique, in patients with portal hypertension.

Can the dopaminergic-related effects of general anesthetics be linked to mechanisms involved in drug abuse and addiction?

BACKGROUND: General anesthetics (GA) are well known for the ability to induce a state of reversible loss of consciousness and unresponsiveness to painful stimuli. However, evidence from animal models and clinical studies show that GA exposure may induce behavioral changes beyond acute effects. Most research and concerns are focused on changes in cognition and memory. METHODS: We will look at effects of GA on behavior that is mediated by the dopaminergic system. RESULTS: Pharmacological resemblance of GA with drugs of abuse, and the complexity and importance of dopaminergic systems in both reward seeking and addictive illnesses make us believe that it deserves an overview about what is already known and what matters to us as healthcare workers and specifically as anesthesiologists. CONCLUSION: A review of available evidence strongly suggests that there may be a link between the effects of GA on the brain and substance abuse, partly explained by their influence on the dopaminergic system.

Trouble dissociatif: une clinique à l'interface de la neurologie et de la psychiatrie [Dissociative disorders: neurologists and psychiatrists working together]

Les troubles dissociatifs se présentent souvent par une clinique neurologique atypique impliquant une démarche diagnostique complexe à l'interface de la neurologie et de la psychiatrie. La restitution du diagnostic aux patients et leur prise en charge nécessitent une étroite collaboration interdisciplinaire. Les connaissances actuelles sont encore limitées, mais ce domaine est enrichi par des études récentes en neurosciences cliniques. Cet article présente les principaux aspects des troubles dissociatifs et formule un concept de prise en charge. Dissociative disorders often have an atypical neurological presentation requiring a complex diagnostic process at the interface between neurology and psychiatry. A strong interdisciplinary collaboration is needed for diagnosis restitution and patient treatment. Current knowledge is still scarce but recent studies in clinical neuroscience enrich this field. This article presents the main aspects of dissociative disorders and suggests a treatment framework