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.

Nausea e vomito em laparoscopia ginecologica: Efeitos do oxido nitroso e da metoclopramida

Background and Objectives - Gynecological laparoscopy causes high postoperative morbidity, mainly due to occurrences such as nausea and vomiting. They result from a great multiplicity of etiologies and drugs used in anesthesia may function as contributing factors. Both the emetic properties of nitrous oxide and the efficacy of metoclopramide as antiemetic agent are controversial. This study was undertaken to determine the effects of both drugs, when used alone or in combination. Methods - Eighty three physical status ASA I and II women were studied. They were premedicated with midazolam before induction of anesthesia with alfentanil and propofol. Anesthesia was maintained with isoflurane with or without nitrous oxide in oxygen. Muscle relaxation was achieved with atracurium. There were 4 groups of patients: GI: midazolam, alfentanil, propofol, atracurium, isoflurane/oxygen; GII: midazolam, alfentanil, propofol, atracurium, isoflurane/nitrous oxide/oxygen; GIII: metoclopramide, midazolam, alfentanil, propofol, atracurium, isoflurane/oxygen; GIV: metoclopramide, midazolam, alfentanil, propofol, atracurium, isoflurane/nitrous oxide/oxygen. The incidence of nausea and vomiting was assessed both in the recovery room (RR) and in the ward. Results - There were no significant differences as regards age, weight and height of the patients and duration of anesthesia and surgery. Nausea and vomiting were more frequent in patients who received N2O (GII, 50%; GIV, 33%), as compared to those who didn't receive this agent (GI and GII, 9.5% and 14.35%, respectively). Metoclopramide decreased the incidence of nausea and vomiting in the recovery room, in patients who didn't receive N2O (GII). These patients remained in the recovery room for 90 minutes. Conclusions - N2O increases the incidence of nausea and vomiting and metoclopramide is effective in reducing these complications only in the recovery room.

Peridural com ropivacaina a 1%: Experiencia com volume proporcional a estatura

Background and Objectives - Ropivacaine - a local amino amide anesthetic agent - is a plain S enantiomer which makes it a potent and low toxicity drug. The aim of our study was to evaluate 1% ropivacaine for epidural block in lower doses than those described in the literature. Methods - Thirty-eight patients, physical status ASA I and II, aged 15 to 70 years, weighing 50 to 100 kg were selected. Premedication consisted of 15 mg oral midazolam given 60 min before anesthesia induction. In the OR, after standard monitoring a catheter was inserted intravenously to administer 10 ml.kg-1 Ringers lactate solution. Epidural puncture was performed with the patient in the sitting position and 1% ropivacaine was administered in a volume corresponding to 10% of patient's height in centimeters. With the patient in the supine position, motor blockade intensity, temperature sensitivity and sensory block extension at 1, 3, 5, 7, 10, 15, 20, 30 minutes after drug injection were evaluated. Blood pressure, heart rate and adverse side effects during the course of anesthesia and in the post-anesthetic period were also observed. In the recovery room patients were followed-up until motor blockade intensity temperature sensitivity and sensory block had returned to level L2. Results - Mean values were 41.4 years of age, 68.8 kg of body weight and 165 cm height. Upper thermal blockade level was T4 and upper sensory block level was T6. Most patients showed motor block level 1 (Bromage scale) after 30 minutes of observation. Motor block mean duration was 254 minutes and temperature sensitivity 426 minutes. Only three patients had complications: two cases of hypotension and one of bradycardia. Conclusions - In the volumes used in this study, ropivacaine produced adequate analgesia and a less intense lower limb motor block which, however, was sufficient to allow for surgical procedures with low incidence of side-effects.

REDUCAO DA CONCENTRACAO ALVEOLAR MINIMA DO ISOFLURANO E DO SEVOFLURANO PELO SUFENTANIL

Background and Objectives - Inhalational anesthetics have a mild analgesic effect. The reduction of alveolar concentration (MAC) of potent volatile anesthesics by increasing plasma concentrations of opioids is desired in inhalational anesthesia. The purpose of this study was to determine the role of sufentanil in reducing sevoflurane and isoflurane MAC. Methods - Thirty eight adult patients of both genders, physical status ASA I or II, submitted to major abdominal procedures were randomly allocated into two groups. Group I (n = 24) received inahalational anesthesia with sevoflurane and Group II (n = 14) received inhalational anesthesia with isoflurane, both diluted in a mixture of N2O (1 liter) and O2 (0.5 liter). A semi-closed system with CO2 absorber and partial reinhalation was used. Ventilation was mechanically controlled. Sufentanil infusion was administered aiming at obtaining 0.5 ng.ml-1 of plasma concentration. Sufentanil plasma concentration was previously calculated by a computer software. End-tidal concentrations were obtained through a gas analyzer and measured at 15 minutes (M1), 30 minutes (M2), 60 minutes (M3), 90 minutes (M4) and 120 minutes (M5). Systolic and diastolic blood pressure (SBP and DBP) and heart rate (RR) were measured during the same periods with the addition of M0 (pre-anesthetic period). Hourly consumption of the inhalational anesthetic agent (IAC), extubation time (ET = time between admission to the recovery room and extubation) and stay in the post anesthesia recovery room (PA-RR) were also measured. Results - Type and duration of surgeries were similar for both groups. There were no statistically significant differences in MAC, SBP, DBP, RR, IAC, TE and PA-RR between groups. Systolic blood pressure in group I (sevoflurane) showed differences among periods F = 3.82 p < O.05; (M2 = M3)(M4 = M5) and M1 had a intermediate value. MAC in group I showed differences among periods F = 9.0 p < 0.05; M1 < M3. MAC in group II also showed differences among periods F = 13.03 p < O.05; M1 < (M2,M3,M4,M5). Conclusions - Both groups had similar behavior when associated to sufentanil in major abdominal surgeries. Group II showed a higher cardiac and circulatory stability.

Associacao de opioides lipofilicos a bupivacaina na anestesia peridural. Ha vantagem no aumento da dose do opioide?

Background and Objectives: - The effects of associating lipophilic opioids to local anesthetics in epidural anesthesia are not well defined. There are still questions and controversies about opioid doses to be used and their major effects in the epidural block. This study aimed at evaluating the epidural block effects in humans of the association of different fentanyl and sufentanil doses to bupivacaine with 1:200.000 epinephrine. Methods: - A double-blind randomized study was performed in 94 patients of both genders, physical status ASA I, aged between 18 and 60 years, submitted to lower abdomen, perineal or lower limb surgery. Patients without preanesthetic medication were epidurally injected with 100 mg (20 ml) 0.5% bupivacaine, 0.1 mg (0.1 ml) 1%o epinephrine plus a combination of the following drugs: BUPI Group (15 patients): 2 ml of 0.9% saline solution (SS); FENT50 Group (19 patients): 50 μg (1 ml) fentanyl + 1 ml SS; FENT100 Group (20 patients): 100 μg (2 ml) fentanyl; SUF30 Group (20 patients): 30 μg (0.6 ml) sufentanil + SS (1.4 ml); SUF100 Group (20 patients): 50 μg (1 ml) sufentanil + SS (1 ml). The following parameters were studied: onset of sensory block, analgesic block (onset time) in T12, T10 and T8, analgesic block duration in T10 and T12, motor block degree, consciousness degree, need for supplemental perioperative sedation and analgesia, hypotension, bradycardia and peri and post operative side-effects, analgesia duration, proportion of patients needing supplemental analgesia and evaluation of postoperative pain (pain analog visual scale). Results: Groups were demographically uniform. The addition of fentanyl or sufentanil did not alter major characteristics of perioperative epidural block and has not significantly increased postoperative analgesia duration as compared to the use of bupivacaine only. However, the addition of lipophilic opioids has increased the quality of perioperative anesthetic block, translated into a lesser need for supplemental analgesia (p < 0.02). The increased dose of fentanyl and especially of sufentanil has increased the incidence of perioperative drowsiness (p < 0.001) without significant increase in other side effects. Conclusions: In the conditions and doses used, the addition of lipophilic opioids to bupivacaine and the increased dose of lipophilic opioids have improved anesthetic block quality without changes in the epidural block characteristics or a significant increase in side effects, with the exception of drowsiness mainly caused by sufentanil. However, they were not able to provide a significant increase in postoperative analgesia duration.

Effects of glucose infusion on the endocrine, metabolic and cardiorespiratory responses to halothane anaesthesia of ponies

Glucose was infused intravenously into six ponies during halothane anaesthesia, to evaluate its effect on their endocrine response to anaesthesia. The ponies were premedicated with acepromazine, and anaesthesia was induced with thiopentone and maintained with halothane in oxygen for two hours. Glucose was infused to maintain the plasma glucose concentration above 20 mmol/litre. Anaesthesia was associated with hypothermia, a decrease in haematocrit, hypotension, hyperoxaemia, respiratory acidosis and an increase in the plasma concentrations of lactate and arginine vasopressin. The concentration of β-endorphin in plasma increased transiently after 20 minutes but there were no changes in concentrations of adrenocorticotrophic hormone, dynorphin, cortisol or catecholamines. These data suggest that the glucose infusion attenuated the normal adrenal response of ponies to halothane anaesthesia.

The effect of changing the mode of ventilation on the arterial-to-end-tidal CO2 difference and physiological dead space in laterally and dorsally recumbent horses during halothane anesthesia

Objective - To evaluate the effect of changing the mode of ventilation from spontaneous to controlled on the arterial-to-end-tidal CO2 difference [P(a-ET)CO2] and physiological dead space (VD(phys)/VT) in laterally and dorsally recumbent halothane-anesthetized horses. Study Design - Prospective, experimental, nonrandomized trial. Animals - Seven mixed breed adult horses (1 male and 6 female) weighing 320 ± 11 kg. Methods - Horses were anesthetized in 2 positions - right lateral and dorsal recumbency - with a minimum interval of 1 month. Anesthesia was maintained with halothane in oxygen for 180 minutes. Spontaneous ventilation (SV) was used for 90 minutes followed by 90 minutes of controlled ventilation (CV). The same ventilator settings were used for both laterally and dorsally recumbent horses. Arterial blood gas analysis was performed every 30 minutes during anesthesia. End-tidal CO2 (PETCO2) was measured continuously. P(a-ET)CO2 and VD(phys)/VT were calculated. Statistical analysis included analysis of variance for repeated measures over time, followed by Student-Newman-Keuls test. Comparison between groups was performed using a paired t test; P < .05 was considered significant. Results - P(a-ET)CO2 and VD(phys)/VT increased during SV, whereas CV reduced these variables. The variables did not change significantly throughout mechanical ventilation in either group. Dorsally recumbent horses showed greater P(a-ET)CO2 and VD(phys)/VT values throughout. PaCO2 was greater during CV in dorsally positioned horses. Conclusions and Clinical Relevance - Changing the mode of ventilation from spontaneous to controlled was effective in reducing P(a-ET)CO2 and physiological dead space in both laterally and dorsally recumbent halothane-anesthetized horses. Dorsal recumbency resulted in greater impairment of effective ventilation. Capnometry has a limited value for accurate estimation of PaCO, in anesthetized horses, although it may be used to evaluate pulmonary function when paired with arterial blood gas analysis. © Copyright 2000 by The American College of Veterinary Surgeons.

Análise das vantagens de duas técnicas anestésicas - Venosa e inalatória - Para colecistectomia por videolaparoscopia

Background and Objectives - It is essential to reduce health care costs without impairing the quality of care. Propofol is associated to faster recovery and it is known that post-anesthesia care unit (PACU) costs are high. The aim of this study was to evaluate the advantages of two anesthesia regimens - propofol continuous infusion or isoflurane - taking into account the cost of both techniques on PACU stay. Methods - Forty seven patients, physical status ASA I, II and III, undergoing laparoscopic cholecystectomy were divided into 2 groups according to the anesthetic agent: G1, conventional propofol continuous infusion (100-150 μg.kg-1.min-1) and G2, isoflurane. All patients were induced with sufentanil (1 μg.kg-1) and propofol (2 mg.kg-1) and were kept in a re-inhalation circuit (2 L.min-1 of fresh gas flow) with 50% N2O in O2, sufentanil (0.01 μg.kg-1.min-1) and atracurium (0.5 mg.kg-1), or pancuronium (0.1 mg.kg-1) for asthma patients. All patients received atropine and neostigmine at the end of the surgery. Prophylactic ondansetron, dipyrone and tenoxican were administered and, when necessary, tramadol and N-butylscopolamine. Costs of anesthetic drugs (COST), total PACU stay (t-PACU), and PACU stay after extubation (t-EXT) were computed for both groups. Results - Costs were significantly lower in the isoflurane group but t-PACU was 26 minutes longer and t-EXT G1agent for laparoscopic cholecystectomy showed lower drug costs as compared to propofol. However, isoflurane group patients stayed longer in PACU as compared to propofol continuous infusion group.

Avaliação experimental dos efeitos do anestésico local ropivacaína em nervos ciáticos

This study was undertaken to investigate the effects of ropivacaine after intrafascicular injection into the sciatic nerves of albino rabbits. Twenty adult albine rabbits were used, following sedation with intramuscular ketamine (50 mg/kg) for nerve exposure by lateral incision. We considered three experimental groups: Group I:sciatic nerve control; Group II: intrafascicular injection with 0.2 mL of physiologic saline solution in the left nerves and intrafascicular injection with 0.2 mL of local anesthetic ropivacaine into the rigth nerves. The specimens were colected at 48 h after drugs administration; Group III. intrafascicular injection with 0.2 mL of physiologic saline solution in the left nerves and intrafascicular injection with 0.2 mL of local anesthetic ropivacaine in the rigth nerves. The specimens were colected at 7 days after drugs administration. The sciatic nerves were removed from these animals and fixed in Karnowisky solution for 24 hours. After partial dehydration up to 95% ethanol, they were embedded in historesin (Leica). The tissue was then sectioned at 1-2μm. Sections were stained with haematoxylin-eosin (HE); toluidine blue (TB) or picrosirius-haematoxylin (PSH). Comparing with control group the histological evidence of inflammatory reaction (migration of macrophagic cells and eosinophils-appeared soon after injection, with intense proliferation of perineurial cells. The results show that after 7 days of intrafascicular injection there was a severe fibrosis and an increase on perineurial vascularization. In group 2 the inflammatory reaction was noted near the local of the injection. Furthermore in this experiment we observed an increase on the number of epineurial lipoblasts and adipocytes. This study demonstrated that the toxic effects of ropivacaine are transient. In many cases there was an initial fascicular recover and axonal regeneration after 7 days of the injection.

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.

Histomorphometric analysis of homogenous demineralized dentin matrix as osteopromotive material in rabbit mandibles

Purpose: The aim of this work was to evaluate the effectiveness of homogenous demineralized dentin matrix (HDDM) slices in surgical bone defects created in the mandibles of rabbits and occluded with a polytetrafluoroethylene (PTFE) membrane in the promotion of bone growth. Materials and Methods: Surgical bone defects were created in 36 adult rabbits and divided into 4 groups: bone defect (control), bone defect with PTFE membrane, bone defect with HDDM, and bone defect with both HDDM and a PTFE membrane (HDDM + PTFE). The rabbits were sacrificed after 30, 60, and 90 days, and the bone defects were examined histologically and by histomorphometric analysis (analysis of variance and the Tukey test). Results: The volume of newly formed bone matrix was significantly greater in the HDDM and HDDM + PTFE groups than in the control and PTFE groups. The discrete inflammatory reaction found in the HDDM and HDDM + PTFE groups did not prevent the osteopromotive activity of the dentin matrix. Discussion: HDDM slices were biocompatible and were resorbed during the bone remodeling process. They stimulated the newly formed bone until 30 days after implantation. Conclusion: Bone repair was accelerated in the bone defects treated with HDDM in comparison to the control group.

Análise retrospectiva da toxicidade de gotas otológicas, medicamentos tópicos nasais e orofaríngeos registrada na Grande São Paulo.

BACKGROUND: Retrospective analysis of human toxicity files involving topical medicines for treatment of upper airways diseases (eardrops, topical nasal medicines, lozenges, drops and sprays for oropharyngeal affections). METHODS: Thirty-four brands of eardrops, 48 of topical nasal medicines and 22 of tablets, lozenges and sprays for oropharyngeal affections were selected, from a total of 104 products available in Brazil. We analyzed the registries in the electronic database from the Poison Control Centre of São Paulo (CCI-Jabaquara), Brazil, for the period from January 1996 through December 2000. The cases related to selected pharmaceuticals were collected. RESULTS: 10,823 cases of human toxicity caused by medicines were voluntarily reported to CCI-Jabaquara. Topical medicines for treatment of upper airways diseases accounted for 291 cases (2.68%), from which 240 (82.5%) represented poisoning; 12 (4.1%) involved ear drops, 268 (92%), topical nasal medicines and 11 (3.9%), topical medicines for oropharyngeal affections. Among topical nasal medicines, vasoconstrictors predominated (233 cases), and among medicines for oropharyngeal affections, it was tetracaine (four cases). Considering age distribution, toxicity predominated significantly in children aged from 1 to 4 years (p=0.0003). The main causes of toxicity were: accidental intake of medicines (43%) and error in drug administration (14.8%). Hypereflexia and vomiting were the most frequent symptoms related to toxicity. CONCLUSIONS: There was significant incidence of systemic toxicity due to eardrops, topical nasal and oropharyngeal medicines in children 1 to 4 years-old, whose main cause was accidental intake of these medicines.

Injeção subaracnóidea inadvertida de corticoíde em tratamento de dor crônica da coluna lombar. Relato de caso

BACKGROUND AND OBJECTIVES: Before epídural steroids were used in chronic lumbar pain, subarachnoid injection of these agents was the treatment of choice. Although still preconized by some authors, this technique may lead to severe complications with neurological sequelae. This report aimed at describing a case of accidental subarachnoid injection of steroid associated to local anesthetics during epidural puncture to treat lumbar pain. CASE REPORT: Male patient, 46 years old, followed byneuro-surgery for presenting right sciatic pain for 9 month, refractory to clinical treatment due to L 4-L 5 disk protrusion confirmed by CT scan, without neurological deficit. Epidural puncture for pain treatment was performed in L 4-L 5 with 17G needle and 10 mL solution were injected containing 4 mL of 0.25% bupivacaine, 80 mg methylprednisolone and 4 mL of 0.9% saline. Although there has not been CSF reflux, 5 minutes after injection there were sensory block in T 4 and motor block in T 6, associated to blood pressure and heart rate decrease. CONCLUSIONS: Accidental subarachnoid injections with the association of steroids for pain relief may cause adverse effects. There are several risks, varying from mild transient symptoms to nervous injuries, including spinal cord injuries. Our patient had no sequelae from the accidental subarachnoid injection, probably because it has been a single injection.