Effect of remifentanil hydrochloride administered via constant rate infusion on the minimum alveolar concentration of isoflurane in cats

Objective - To evaluate the effects of increasing doses of remifentanil hydrochloride administered via constant rate infusion (CRI) on the minimum alveolar concentration (MAC) of isoflurane in cats. Animals - 6 healthy adult cats. Procedures - For each cat, 2 experiments were performed (2-week interval). On each study day, anesthesia was induced and maintained with isoflurane; a catheter was placed in a cephalic vein for the administration of lactated Ringer's solution or remifentanil CRIs, and a catheter was placed in the jugular vein for collection of blood samples for blood gas analyses. On the first study day, individual basal MAC (MAC Basal) was determined for each cat. On the second study day, 3 remifentanil CRIs (0.25, 0.5, and 1.0 μg/kg/min) were administered (in ascending order); for each infusion, at least 30 minutes elapsed before determination of MAC (designated as MAC R0.25, MAC R0.5, and MAC R1.0, respectively). A 15-minute washout period was allowed between CRIs. A control MAC (MAC Control) was determined after the last remifentanil infusion. Results - Mean ± SD MAC Basal and MAC Control values at sea level did not differ significantly (1.66 ± 0.08% and 1.52 ± 0.21%, respectively). The MAC values determined for each remifentanil CRI did not differ significantly. However, MAC R0.25, MAC R0.5, and MAC R1.0, were significantly decreased, compared with MAC Basal, by 23.4 ± 79%, 29.8 ± 8.3%, and 26.0 ± 9.4%, respectively. Conclusions and Clinical Relevance - The 3 doses of remifentanil administered via CRI resulted in a similar degree of isoflurane MAC reduction in adult cats, indicating that a ceiling effect was achieved following administration of the lowest dose.

Anestesia para colecistectomía videolaparoscópica en paciente portador de enfermedad de Steinert. Relato de caso y revisiõn de la literatura

BACKGROUND AND OBJECTIVES: Myotonic dystrophies are autosomal dominant neuromuscular diseases. Among them, myotonic dystrophy type 1 (MD1), or Steinert disease, is the most common in adults, and besides muscular involvement it also has important systemic manifestations. Myotonic dystrophy type 1 poses a challenge to the anesthesiologist. Those patients are more sensitive to anesthetics and prone to cardiac and pulmonary complications. Besides, the possibility of developing malignant hyperthermia and myotonic episodes is also present. CASE REPORT: This is a 39-year old patient with DM1 who underwent general anesthesia for videolaparoscopic cholecystectomy. Total intravenous anesthesia with propofol, remifentanil, and rocuronium was the technique chosen. Intercurrences were not observed in the 90-minute surgical procedure, but after extubation, the patient developed respiratory failure and myotonia, which made tracheal intubation impossible. A laryngeal mask was used, allowing adequate oxygenation, and mechanical ventilation was maintained until full recovery of the respiratory function. The patient did not develop further complications. CONCLUSIONS: Myotonic dystrophy type 1 presents several particularities to the anesthesiologist. Detailed knowledge of its systemic involvement along with the differentiated action of anesthetic drugs in those patients will provide safer anesthetic-surgical procedure.

Pharmacokinetics of dexmedetomidine administered intravenously in isofluraneanesthetized cats

Objective-To determine the pharmacokinetics of dexmedetomidine administered as a short-duration IV infusion in isoflurane-anesthetized cats. Animals-6 healthy adult domestic female cats. Procedures-Dexmedetomidine hydrochloride was injected IV (10 μg/kg over 5 minutes [rate, 2 μg/kg/min]) in isoflurane-anesthetized cats. Blood samples were obtained immediately prior to and at 1, 2, 5, 6, 7, 10, 15, 30, 60, 90, 120, 240, and 480 minutes following the start of the IV infusion. Collected blood samples were transferred to tubes containing EDTA, immediately placed on ice, and then centrifuged at 3,901 X g for 10 minutes at 4°C. The plasma was harvested and stored at -20°C until analyzed. Plasma dexmedetomidine concentrations were determined by means of liquid chromatography-mass spectrometry. Dexmedetomidine plasma concentration-time data were fitted to compartmental models. Results-A 2-compartment model with input in and elimination from the central compartment best described the disposition of dexmedetomidine administered via short-duration IV infusion in isoflurane-anesthetized cats. Weighted mean ± SEM apparent volume of distribution of the central compartment and apparent volume of distribution at steady-state were 402 ± 47 mL/kg and 1,701 ± 200 mL/kg, respectively; clearance and terminal half-life (harmonic mean ± jackknife pseudo-SD) were 6.3 ± 2.8 mL/min/kg and 198 ± 75 minutes, respectively. The area under the plasma concentration curve and maximal plasma concentration were 1,061 ± 292 min·ng/mL and 17.6 ± 1.8 ng/mL, respectively. Conclusions and Clinical Relevance-Disposition of dexmedetomidine administered via short-duration IV infusion in isoflurane-anesthetized cats was characterized by a moderate clearance and a long terminal half-life.

Analgésicos Tópicos

Background and objectives: Pain treatment involves the usage of common and opioid analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs) and adjuvant analgesics. Traditionally, these drugs are administered systemically or into the neuraxis. However, when analgesics are applied through these pathways, they are associated with significant side effects, which can hinder its use. Topical administration of analgesics is an alternative. The objective of this paper is to discuss topical analgesics, the mechanisms of action and clinical efficacy. Content: This is a review paper addressing the usage of the topical local anesthetics: capsaicin, clonidine, tricyclic antidepressants, ketamine, opioids and cannabinoids, discussing mechanism of action and effectiveness. Conclusions: Topical analgesics are promising as a strategy for pain treatment, as they are associated with lower incidence of side effects. The benefit of local anesthetics, NSAID's and capsaicin is well established. However, the efficacy of clonidine, tricyclic antidepressants, ketamine, opioids and cannabinoids is still questionable. Studies have shown that the multimodal approach is an alternative, but studies are needed to confirm this hypothesis. © 2012 Elsevier Editora Ltda.

Effect of dexmedetomidine on the minimum alveolar concentration of isoflurane in cats

This study reports the effects of dexmedetomidine on the minimum alveolar concentration of isoflurane (MAC iso) in cats. Six healthy adult female cats were used. MAC iso and dexmedetomidine pharmacokinetics had previously been determined in each individual. Cats were anesthetized with isoflurane in oxygen. Dexmedetomidine was administered intravenously using target-controlled infusions to maintain plasma concentrations of 0.16, 0.31, 0.63, 1.25, 2.5, 5, 10, and 20ng/mL. MAC iso was determined in triplicate at each target plasma dexmedetomidine concentration. Blood samples were collected and analyzed for dexmedetomidine concentration. The following model was fitted to the concentration-effect data: where MAC iso.c is MAC iso at plasma dexmedetomidine concentration C, MAC iso.0 is MAC iso in the absence of dexmedetomidine, I max is the maximum possible reduction in MAC iso, and IC 50 is the plasma dexmedetomidine concentration producing 50% of I max. Mean±SE MAC iso.0, determined in a previous study conducted under conditions identical to those in this study, was 2.07±0.04. Weighted mean±SE I max, and IC 50 estimated by the model were 1.76±0.07%, and 1.05±0.08ng/mL, respectively. Dexmedetomidine decreased MAC iso in a concentration-dependent manner. The lowest MAC iso predicted by the model was 0.38±0.08%, illustrating that dexmedetomidine alone is not expected to result in immobility in response to noxious stimulation in cats at any plasma concentration. © 2011 Blackwell Publishing Ltd.

Preparation and characterization of poly(ε-caprolactone) nanospheres containing the local anesthetic lidocaine

The objective of this work was to develop a modified release system for the local anesthetic lidocaine (LDC), using poly(ε-caprolactone) (PCL) nanospheres (NSs), to improve the pharmacological properties of the drug when administered by the infiltration route. In vitro experiments were used to characterize the system and investigate the release mechanism. The NSs presented a polydispersion index of 0.072, an average diameter of 449.6nm, a zeta potential of -20.1mV, and an association efficiency of 93.3%. The release profiles showed that the release of associated LDC was slower than that of the free drug. Atomic force microscopy analyses showed that the spherical structure of the particles was preserved as a function of time, as well as after the release experiments. Cytotoxicity and pharmacological tests confirmed that association with the NSs reduced the toxicity of LDC, and prolonged its anesthetic action. This new formulation could potentially be used in applications requiring gradual anesthetic release, especially dental procedures. © 2012 Wiley Periodicals, Inc.

Dental students' familiarity with the medical management of dental patients at Brazilian dental schools

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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.

Comparison of inflammatory cytokine profiles in plasma of patients undergoing otorhinological surgery with propofol or isoflurane anesthesia

Objective and design: The effects of anesthetics on cytokine release in patients without comorbidities who undergo minor surgery are not well defined. We compared inflammatory cytokine profiles in adult patients undergoing minimally invasive surgery who received isoflurane or propofol anesthesia. Methods: Thirty-four patients without comorbidities undergoing minor surgery were randomly assigned to receive an inhaled anesthetic (isoflurane; n = 16) or an intravenous anesthetic (propofol; n = 18). Blood samples were drawn before premedication and anesthesia (T1), 120 min after anesthesia induction (T2), and on the first post-operative day (T3). Plasma concentrations of interleukins (IL-) 1β, 6, 8, 10 and 12 and tumor necrosis factor (TNF)-α were measured using flow cytometry. Results: The pro-inflammatory cytokine IL-6 was increased in the isoflurane group at T2 and T3 compared to T1 (P < 0.01). In the propofol group, IL-6 and IL-8 were significantly increased at T3 compared to T1. However, there were no significant differences in cytokine concentrations between the isoflurane and propofol groups. Conclusion: An inflammatory response occurred earlier in patients who received an inhaled agent compared with an intravenous anesthetic, but no differences in plasma cytokine profiles were evident between isoflurane and propofol anesthesia in patients without comorbidities undergoing minimally invasive surgeries. © 2013 Springer Basel.

Dosagem de NGAL no perioperatório de cirurgia bariátrica videolaparoscópica: comparação de Anestesia Venosa Total (TIVA) versus Sevoflurano

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Carcinogênese quimicamente induzida por DMBA em glândulas salivares submandibulares de ratos (rattus norvegicus)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Infusão contínua de morfina ou fentanil, associados à licodaína e cetamina, em cães anestesiados com isofluorano

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos do cloridrato de remifentanil, administrado em infusão contínua, na concentração alveolar mínima(CAM) de isofluorano em felinos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Velhas drogas, novas terapêuticas: investigação da utilização de antagonistas de adrenoceptores α1 e de bloqueadores de canais de cálcio no retardo da ejaculação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise químico-farmacêutica de azumoleno sódico

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)