Combined effects of melatonin and topical hypothermia on renal ischemia-reperfusion injury in rats

Purpose: To evaluate whether their combination was more effective than either alone in decreasing renal damage due to ischemia/reperfusion (I/R) injury in rats. Methods: Thirty-two Wistar rats were assigned to four groups. Following right nephrectomy, their left kidneys were subjected to warm ischemia (IR), cold ischemia (TH+IR), intraperitoneal injection of 10 mg/kg melatonin (MEL+IR), or injection of 10 mg/kg melatonin followed by cold ischemia (MEL+TH+IR). Eight randomly assigned right kidneys constituted the control group. After 240 min of reperfusion, left nephrectomy was performed for histopathological evaluation, lipid peroxidation, and measurement of antioxidant enzyme activity. Serum was collected to measure urea and creatinine concentrations. Results: Histopathological damage induced by ischemia and reperfusion was more attenuated in the MEL+TH+IR group than in the MEL+IR and TH+IR groups (p<0.037). Superoxide dismutase activity was significantly higher (p<0.029) and creatinine (p<0.001) and urea (p<0.001) concentrations were significantly lower in the MEL+TH+IR group than in the MEL+IR and TH+IR groups. Conclusion: The combination of melatonin (MEL) and topical hypothermia (TH) better protects against renal I/R injury than does MEL or TH alone.(AU)

Adipose tissue derived mesenchymal stem cell transplantation in the treatment of ischemia/reperfusion induced acute kidney injury in rats. Application route and therapeutic window

Purpose:To evaluate renal repair in rats who had renal infarction induced by the obstruction of blood flow in the renal artery and were treated with transplantation of adipose tissue derived mesenchymal stem cellMethods:16-week-old Wistar rats (n=72) were used, submitted to celiotomy and had of the renal artery and vein clipped for 24 hours. The animals were randomly assigned to 10 experimental homogeneous groups, corresponding to the treatments with phosphate-buffered saline (PBS) or adipose tissue derived mesenchymal stem cell (ADSC), duration of application (24 or 48 hours), and site of transplantation (lateral vein of the tail or intrarenal). After the treatments were performed, at 8 and 31 days, four animals in each group were subjected to left nephrectomy for histological studies.Results:Histologically, a higher amount of cell debris and tubules devoid of the epithelium and a higher degree of necrosis were observed in the groups treated with PBS, as opposed to a low degree of necrosis and higher tubular vascularization in the groups treated with ADSC, particularly in the group treated with intrarenal ADSC 48 hours after injury.Conclusion:The transplantation of ADSC positively contributed to the replacement of necrotic tissue by renal tubular cells, vascularization of the renal parenchyma, and restoration of the organ function.(AU)

Minimum alveolar concentration of isoflurane in dogs administered a single intramuscular injection of racemic or S (+)-ketamine after premedication with acepromazine-morphine / Concentração alveolar mínima do isoflurano em cães tratados com dose única intramuscular de cetamina racêmica ou S (+) após premedicação com acepromazina-morfina

The present study evaluated the minimum alveolar concentration of isoflurane (ISOMAC) in twenty three dogs premedicated with acepromazine (0.02mgkg-1) and morphine (0.5mgkg-1) and administered racemic (RK) or S(+)-ketamine (SK). Dogs randomly received a single dose (3mgkg-1, IM) of either RK or SK 15minutes after anesthetic induction with propofol. The ISOMAC was determined by the up-and-down method. Approximately 20 minutes after administration of RK or SK, a surgical noxious stimulus was applied and the response evaluated. The ISOMAC was 0.50±0.01% in the RK group (n=10) and 0.31±0.04% in the SK group (n=13). The ISOMAC was 38% lower in the SK group compared to the RK group. Results of the present study revealed that in dogs premedicated with acepromazine and morphine, IM administration of 3mgkg-1 ketamine approximately 20 minutes before the noxious stimulus produced clinically important reduction in the ISOMAC and the MAC-sparing effect was significantly greater with SK compared to RK.

No presente estudo, foi avaliada a concentração alveolar mínima do isoflurano (CAMISO) em vinte e três cães premedicados com acepromazina (0,02mgkg-1) e morfina (0,5mgkg-1) e tratados com cetamina racêmica (CR) ou S(+) (CS). Os cães receberam aleatoriamente dose única (3mgkg-1, IM) de CR ou CS, decorridos 15 minutos da indução anestésica com propofol. A CAMISO foi determinada pelo método up-and-down. Aproximadamente 20 minutos após a administração da CR ou CS, um estímulo nociceptivo (cirúrgico) foi aplicado e a resposta avaliada. A CAMISO foi 0,50±0,01% no CR (n=10) e 0,31±0,04% no CS (n=13). A CAMISO foi 38% menor no CS comparado ao CR. Os resultados deste estudo revelaram que, em cães premedicados com acepromazina e morfina, a administração IM de 3mgkg-1 de cetamina, aproximadamente 20 minutos antes do estímulo nociceptivo, causou redução clinicamente importante na CAMISO e o efeito redutor na CAMISO é significativamente maior com CS do que com CR.

Minimum alveolar concentration of isoflurane in dogs administered a single intramuscular injection of racemic or S (+)-ketamine after premedication with acepromazine-morphine / Concentração alveolar mínima do isoflurano em cães tratados com dose única intramuscular de cetamina racêmica ou S (+) após premedicação com acepromazina-morfina

The present study evaluated the minimum alveolar concentration of isoflurane (ISOMAC) in twenty three dogs premedicated with acepromazine (0.02mgkg-1) and morphine (0.5mgkg-1) and administered racemic (RK) or S(+)-ketamine (SK). Dogs randomly received a single dose (3mgkg-1, IM) of either RK or SK 15minutes after anesthetic induction with propofol. The ISOMAC was determined by the up-and-down method. Approximately 20 minutes after administration of RK or SK, a surgical noxious stimulus was applied and the response evaluated. The ISOMAC was 0.50±0.01% in the RK group (n=10) and 0.31±0.04% in the SK group (n=13). The ISOMAC was 38% lower in the SK group compared to the RK group. Results of the present study revealed that in dogs premedicated with acepromazine and morphine, IM administration of 3mgkg-1 ketamine approximately 20 minutes before the noxious stimulus produced clinically important reduction in the ISOMAC and the MAC-sparing effect was significantly greater with SK compared to RK.(AU)

No presente estudo, foi avaliada a concentração alveolar mínima do isoflurano (CAMISO) em vinte e três cães premedicados com acepromazina (0,02mgkg-1) e morfina (0,5mgkg-1) e tratados com cetamina racêmica (CR) ou S(+) (CS). Os cães receberam aleatoriamente dose única (3mgkg-1, IM) de CR ou CS, decorridos 15 minutos da indução anestésica com propofol. A CAMISO foi determinada pelo método up-and-down. Aproximadamente 20 minutos após a administração da CR ou CS, um estímulo nociceptivo (cirúrgico) foi aplicado e a resposta avaliada. A CAMISO foi 0,50±0,01% no CR (n=10) e 0,31±0,04% no CS (n=13). A CAMISO foi 38% menor no CS comparado ao CR. Os resultados deste estudo revelaram que, em cães premedicados com acepromazina e morfina, a administração IM de 3mgkg-1 de cetamina, aproximadamente 20 minutos antes do estímulo nociceptivo, causou redução clinicamente importante na CAMISO e o efeito redutor na CAMISO é significativamente maior com CS do que com CR.(AU)

Minimum alveolar concentration of isoflurane in dogs administered two morphine doses / Concentração alveolar mínima do isoflurano em cães tratados com duas doses de morfina

This study aimedto evaluate the effects of intramuscular 0.5mg kg-1 (MOR0.5) and 1.0mg kg-1 (MOR1.0) morphine premedication on the minimum alveolar concentration of isoflurane (ISOMAC) in dogs. Eighteen client-owned female dogs were scheduled for elective ovariohysterectomy. Dogs received intramuscular MOR0.5 or MOR1.0 as premedication and propofol IV for induction of anesthesia. Isoflurane was delivered for maintenance of anesthesia and dogs were maintained under normocapnia and normothermia. Determinations of the ISOMACwere conducted by use of the “up-and-down” method. Noxious stimulus (placement of Backhaus towel clamps, a midline skin incision and subcutaneous tissue dissection) was delivered approximately 50 minutes after premedication with MOR0.5 or MOR1.0. The calculated ISOMACwas 0.98±0.15% in MOR0.5 and 0.80±0.08% in MOR1.0. The ISOMAC was significantly lower in MOR1.0 compared with MOR0.5 (P=0.010). Results of this study suggested that intramuscular premedication with morphine 0.5 and 1.0mg kg-1 decreases the ISOMAC in a dose-related manner in dogs.(AU)

O presente estudo objetivou avaliar os efeitos da administração intramuscular de 0,5mg kg-1 (MOR0,5) ou 1,0mg kg-1 (MOR1,0) de morfina sobre a concentração alveolar mínima do isoflurano (CAMISO) em cães. Dezoito cadelas de proprietários foram agendadas para ovário-histerectomia eletiva. As cadelas receberam MOR0,5 ou MOR1,0, como medicação pré-anestésica, e propofol IV para indução da anestesia. A manutenção da anestesia foi realizada com isoflurano em condições de normocapnia a normotermia. A determinação da CAMISOfoi conduzida de acordo com o método “up-and-down”. O estímulo nociceptivo (colocação de pinças Backhaus, incisão da pele na linha média e dissecção de tecido subcutâneo) foi realizado aproximadamente 50 minutos após a administração de MOR0,5 ou MOR1,0. A CAMISO calculada foi 0,98±0,15% em MOR0,5 e 0,80±0,08% em MOR1,0. A CAMISO foi significativamente menor em MOR1,0 do que em MOR0,5 (P=0,010). Os resultados do estudo sugerem que a medicação pré-anestésica com morfina nas doses de 0,5 e 1,0mg kg-1, pela via intramuscular, resulta em redução dose-dependente na CAMISO em cães.(AU)

Concordância entre o monitor oscilométrico Petmap e o Doppler ultrassônico para mensuração da pressão arterial sistólica em cães conscientes / Agreement between the Petmap oscillometric device and Doppler ultrasonic for systolic blood pressure measurement in conscious dogs

Background: Arterial blood pressure (BP) monitoring is essential to evaluate cardiovascular performance in clinical practice and during anesthetic procedures in veterinary patients. Measurement of blood pressure can be performed directly (invasively) or indirectly (non invasively). When using non-invasive methods such as the Doppler ultrasonic and oscillometric devices, the accuracy of these methods should be evaluated before they can be used in clinical practice. The present study aimed to determine the agreement between systolic arterial blood pressure (SAP) measured by the Doppler ultrasonic and the Petmap oscillometric device in conscious dogs.Materials, Methods & Results: Thirty one healthy dogs weighing 13.2 ± 4.5 kg were used. The dogs were positioned in lateral recumbency and SAP measurements were performed in the non-dependent thoracic limb. All blood pressure measurements were performed using the blood pressure cuff provided by the manufacturer of the Petmap device. The cuff was positioned proximal to the carpus and its width was approximately 50% of limb circumference. Blood pressure measurements with the Doppler ultrasonic were conducted using a standard technique. A sphygmomanometer was connected to the cuff and the Doppler flow probe was positioned over the common metacarpal artery after the hair was clipped and conductive gel was applied. Three consecutive measurements of SAP were obtained with the Doppler and the mean was used for analysis. Immediately after measurements with the Doppler, the blood pressure cuff was connected to the Petmap, a single automated measurement was obtained and the SAP value was recorded. For each dog, eight pairs of SAP measurements (Doppler measurements followed by the Petmap measurement) were obtained with a minimum of 5-min intervals.[...](AU)

Concordância entre o monitor oscilométrico Petmap e o Doppler ultrassônico para mensuração da pressão arterial sistólica em cães conscientes / Agreement between the Petmap oscillometric device and Doppler ultrasonic for systolic blood pressure measurement in conscious dogs

Background: Arterial blood pressure (BP) monitoring is essential to evaluate cardiovascular performance in clinical practice and during anesthetic procedures in veterinary patients. Measurement of blood pressure can be performed directly (invasively) or indirectly (non invasively). When using non-invasive methods such as the Doppler ultrasonic and oscillometric devices, the accuracy of these methods should be evaluated before they can be used in clinical practice. The present study aimed to determine the agreement between systolic arterial blood pressure (SAP) measured by the Doppler ultrasonic and the Petmap oscillometric device in conscious dogs.Materials, Methods & Results: Thirty one healthy dogs weighing 13.2 ± 4.5 kg were used. The dogs were positioned in lateral recumbency and SAP measurements were performed in the non-dependent thoracic limb. All blood pressure measurements were performed using the blood pressure cuff provided by the manufacturer of the Petmap device. The cuff was positioned proximal to the carpus and its width was approximately 50% of limb circumference. Blood pressure measurements with the Doppler ultrasonic were conducted using a standard technique. A sphygmomanometer was connected to the cuff and the Doppler flow probe was positioned over the common metacarpal artery after the hair was clipped and conductive gel was applied. Three consecutive measurements of SAP were obtained with the Doppler and the mean was used for analysis. Immediately after measurements with the Doppler, the blood pressure cuff was connected to the Petmap, a single automated measurement was obtained and the SAP value was recorded. For each dog, eight pairs of SAP measurements (Doppler measurements followed by the Petmap measurement) were obtained with a minimum of 5-min intervals.[...]

Comparação da contenção farmacológica com cetamina e xilazina, administradas pela via intramuscular no membro torácico ou pélvico, em jacarés-do-papo-amarelo juvenis / Comparison of pharmacological restraint with ketamine and xylazine, administered intramuscularly in the forelimb or hindlimb, in broad-snouted caiman juveniles

Os répteis possuem um sistema porta-renal, o qual pode desviar parte do sangue proveniente das porções caudais do corpo aos rins antes que a mesma atinja a circulação sistêmica. Em vista disto, vem sendo aconselhada a administração de medicamentos injetáveis nos membros torácicos, para que se evite a filtração imediata pelo parênquima renal, causando redução do efeito esperado. O objetivo do presente estudo foi comparar aspectos qualitativos e quantitativos da associação de cetamina (30 mg/kg) e xilazina (1 mg/kg), injetada no membro torácico ou pélvico, em jacarés-do-papo-amarelo (Caiman latirostris) juvenis. Oito animais machos com peso médio (±DP) de 1,3 (±0,3) kg e, aproximadamente, dois anos de idade foram anestesiados em duas ocasiões distintas com intervalo de sete dias. Em cada ocasião, os animais receberam, de forma aleatória, a associação anestésica por via intramuscular em membro torácico (tratamento MT) ou pélvico (tratamento MP). Foram avaliados os intervalos de tempo entre a administração do tratamento e a perda do reflexo de endireitamento (período de indução), entre a perda e o retorno desse reflexo (duração do efeito clínico importante) e entre o retorno do reflexo de endireitamento e os primeiros movimentos de deambulação (duração do efeito residual), as frequências cardíaca e respiratória e as temperaturas ambiental e cloacal. Os escores de sedação/anestesia foram avaliados através de uma escala com variação de 0 (alerta/consciente) a 10 (anestesia profunda/sobredosagem). No tratamento MP, dois animais não apresentaram perda de reflexo de endireitamento. Considerando somente aqueles que apresentaram a perda desse reflexo, o tempo de indução (21±9 e 17±5 minutos) e a duração do efeito clínico importante (35±19 e 43±21 minutos) e residual (28±31 e 12±11 minutos) foram similares entre os tratamentos MT e MP (média±desvio padrão). O escore de sedação foi significativamente maior que o basal de 20 a 50 minutos nos dois tratamentos e, aos 30 minutos (pico de efeito), o escore mediano (interquartil) foi 3,5(2,3-4,0) no tratamento MT e 3,0(2,0-4,0) no tratamento MP. Assim como nos escores de sedação, diferenças entre tratamentos nas variáveis fisiológicas não foram observadas. Em ambos os tratamentos, o reflexo de retirada de membro ao pinçamento digital não foi abolido. A administração da associação de xilazina e cetamina em membro pélvico ou torácico de jacarés-do-papo-amarelo juvenis promove efeitos similares, sugerindo que a influência do sistema porta-renal não é clinicamente relevante. Nas doses empregadas, tal protocolo não promove anestesia cirúrgica e a imobilidade/contenção farmacológica é imprevisível e de curta duração.(AU)

Reptiles possess a renal portal system which can divert part of the blood from the caudal portions of the body to the kidney before it reaches the systemic circulation. In view of this, it has been recommended the administration of injectable medications in the forelimbs, in order to avoid immediate glomerular filtration, which might result in a reduction of the expected effect. The aim of this study was to compare qualitative and quantitative aspects of the pharmacological restraint provided by the combination of ketamine (30mg/kg) and xylazine (1mg/kg), injected into the forelimb or hindlimb, in broad-snouted caiman juveniles (Caiman latirostris). Eight male animals, with a mean weight (±SD) of 1.3 (±0.3) kg, and aged about 2 years old, were anesthetized on two separate occasions with an interval of 7 days. On each occasion, the animals were randomly assigned to receive the anesthetic combination intramuscularly into the forelimb (FL treatment) or hindlimb (HL treatment). The time intervals between administration of treatment and loss of the righting reflex (induction time), between the loss and return of this reflex (duration of important clinical effect), and between the return of the righting reflex and first movements of ambulation (duration of residual effect) were measured as well as heart and respiratory rates and cloacal and environmental temperatures. Sedation/anesthesia scores were evaluated using a scale ranging from 0 (alert/conscious) to 10 (deep anesthesia/overdose). In the HL treatment, loss of righting reflex was not observed in two animals. Considering only those animals whose loss of righting reflex was observed, the induction time (21±9 and 17±5 minutes), the duration of important clinical effect (35±19 and 43±21 minutes), and the duration of residual effect (28±31 and 12±11 minutes) were similar between the FL and HL treatments, respectively (mean±SD). Sedation/anesthesia scores were significantly higher than at baseline from 20 to 50 minutes in both treatments and, at 30 minutes (peak sedative effect), the median score (interquartile range) was 3.5(2.3-4.0) in the FL treatment and 3.0(2.0-4.0) in the HL treatment. Differences between treatments in physiological variables were not observed. In both treatments, withdrawal reflex in response to digital clamping was not absent at any timepoint. The administration of xylazine-ketamine combination in the forelimb or hindlimb of broad-snouted caiman juveniles provides similar effects, suggesting that the influence of the renal portal system is not clinically relevant. At the doses used, such combination does not induce surgical anesthesia and the immobility/pharmacological restraint is unpredictable and of short duration.(AU)

Efeitos sedativo e cardiorrespiratório da administração da metadona, isoladamente ou em associação à acepromazina ou xilazina, em gatos / Sedative and cardiorespiratory effects of methadone, alone or in combination with acepromazine or xylazine, in cats

Seis felinos com peso médio de 3,3±0,3 kg foram aleatoriamente submetidos a 6 tratamentos, com intervalo mínimo de 1 semana. Os animais receberam a administração intramuscular de solução fisiológica (controle), metadona (0,3 mg/kg), acepromazina (0,1 mg/kg), xilazina (1,0 mg/kg), acepromazina (0,05 mg/kg) + metadona (0,3 mg/kg) ou xilazina (0,5 mg/kg) + metadona (0,3 mg/kg). As freqüências cardíaca (FC) e respiratória (FR), a pressão arterial sistólica (PAS), a temperatura retal, o grau de sedação e o reflexo interdigital foram avaliados antes (basal) e após a administração dos tratamentos em intervalos específicos por 90 minutos. Nos animais tratados com xilazina ou xilazina/metadona, houve diminuição em FR, FC e na temperatura retal. Nos mesmos tratamentos, 1/6 e 2/6 animais não apresentaram reflexo interdigital em pelo menos um dos momentos avaliados. Nos animais que receberam a administração de 0,1 mg/kg de acepromazina, houve diminuição em PAS. Os escores de sedação foram mais elevados nos animais que receberam a administração de xilazina ou xilazina associada à metadona. A administração da metadona isolada ou associada à acepromazina resultou em sedação considerada insatisfatória e sinais de excitação em alguns animais. O uso da metadona isolado ou em associação à acepromazina foi considerado ineficaz quando se objetiva sedação moderada à intensa. A associação da metadona à xilazina produz sedação moderada à intensa, sendo esse efeito semelhante àquele observado após a administração da xilazina isoladamente em dose mais elevada.(AU)

Six cats weighting 3.3±0.3 kg were randomly allocated to 6 treatments, with at least one-week intervals. The cats received intramuscular administration of physiological saline (control), methadone (0.3 mg/kg), acepromazine (0,1 mg/kg), xylazine (1.0 mg/kg), acepromazine (0.05 mg/kg) plus methadone (0.3 mg/kg) or xylazine (0.5 mg/kg) plus methadone (0.3 mg/kg). Heart rate (HR), respiratory rate (RR), indirect systolic arterial pressure (SAP), rectal temperature, sedation score and pedal withdrawal reflex were evaluated before (baseline) and at selected intervals after treatment administration for 90 minutes. Respiratory rate, HR and rectal temperature decreased in cats given xylazine or xylazine plus methadone. In 1 out of 6 cats given xylazine and 2 out of 6 cats given xylazine/methadone, pedal withdrawal reflex was absent. In cats given 0.1 mg/kg of acepromazine, SAP decreased compared to baseline. Sedation scores were greater in cats given xylazine or xylazine plus methadone. Methadone alone or in combination with acepromazine did not produce a satisfactory degree of sedation and resulted in signs of excitement in some of the cats. Methadone alone or combination with acepromazine was not considered an effective protocol when moderate to deep sedation is required in cats. Methadone in combination with xylazine produces moderate to deep sedation, being this effect comparable to that achieved with a higher dose of xylazine alone.(AU)

Fentanil ou remifentanil em cães? Prós e contras, qual escolher e como usar Revisão de Literatura / Fentanyl or Remifentanil in dogs? Pros and cons, which one to choose and how to use -Literature Review

O fentanil e o remifentanil são opióides sintéticos, pertencentes ao grupo das fenilpiperidinas e são agonistasseletivos para receptores μ. Possuem alta potência analgésica, com ação de ultra-curta duração. Oremifentanil difere do fentanil principalmente por possuir características farmacocinéticas únicas, sendo ideal para o uso em infusões contínuas prolongadas. Esses fármacos estão indicados para uso sob a formade infusão intravenosa contínua para promover analgesia no período intra-operatório, além de possibilitarema redução da concentração alveolar mínima dos anestésicos inalatórios. Assim como os demaisopióides, o fentanil e remifentanil causam efeitos adversos como bradicardia e depressão respiratória,sendo indicada a ventilação artificial quando associados aos anestésicos gerais. Devido ao curto períodode ação desses fármacos, há necessidade de suplementação analgésica após o término da infusão, com o intuito de promover analgesia pós-operatória. O uso do remifentanil pode ser vantajoso em relação aofentanil em procedimentos que requeiram infusões prolongadas, em pacientes hepatopatas e nefropatase em outras situações que necessitem de recuperação anestésica rápida, enquanto sua principal desvantagemestá relacionada ao alto custo em relação ao fentanil.

Fentanyl and remifentanil are synthetic opioids which belong to the phenylpiperidine group and areselective agonists for μ receptors. They are potent ultra short-acting opioids. Remifentanil differs fromfentanyl mainly by its unique pharmacokinetic profile, which favors its use in prolonged continuous infusions.These drugs are indicated for use as intravenous constant rate infusion to provide intraoperativeanalgesia and also to decrease the minimum alveolar concentration of inhalational anesthetics. Like otheropioids, fentanyl and remifentanil cause adverse effects such as bradycardia and respiratory depression.Artificial ventilation is recommended when its administered in combination with general anesthetics.Due to the short duration of action of these drugs, analgesic supplementation after discontinuation of theinfusion is necessary to provide postoperative analgesia. The use of remifentanil may be advantageousover fentanyl in procedures requiring prolonged infusions, in patients with liver or kidney disease and for other occasions which require fast recovery from anesthesia, where as the disadvantage is the highcost compared to fentanyl.(AU)

Fentanil ou remifentanil em cães? Prós e contras, qual escolher e como usar – Revisão de Literatura / Fentanyl or Remifentanil in dogs? Pros and cons, which one to choose and how to use -Literature Review

O fentanil e o remifentanil são opióides sintéticos, pertencentes ao grupo das fenilpiperidinas e são agonistasseletivos para receptores μ. Possuem alta potência analgésica, com ação de ultra-curta duração. Oremifentanil difere do fentanil principalmente por possuir características farmacocinéticas únicas, sendo ideal para o uso em infusões contínuas prolongadas. Esses fármacos estão indicados para uso sob a formade infusão intravenosa contínua para promover analgesia no período intra-operatório, além de possibilitarema redução da concentração alveolar mínima dos anestésicos inalatórios. Assim como os demaisopióides, o fentanil e remifentanil causam efeitos adversos como bradicardia e depressão respiratória,sendo indicada a ventilação artificial quando associados aos anestésicos gerais. Devido ao curto períodode ação desses fármacos, há necessidade de suplementação analgésica após o término da infusão, com o intuito de promover analgesia pós-operatória. O uso do remifentanil pode ser vantajoso em relação aofentanil em procedimentos que requeiram infusões prolongadas, em pacientes hepatopatas e nefropatase em outras situações que necessitem de recuperação anestésica rápida, enquanto sua principal desvantagemestá relacionada ao alto custo em relação ao fentanil.

Fentanyl and remifentanil are synthetic opioids which belong to the phenylpiperidine group and areselective agonists for μ receptors. They are potent ultra short-acting opioids. Remifentanil differs fromfentanyl mainly by its unique pharmacokinetic profile, which favors its use in prolonged continuous infusions.These drugs are indicated for use as intravenous constant rate infusion to provide intraoperativeanalgesia and also to decrease the minimum alveolar concentration of inhalational anesthetics. Like otheropioids, fentanyl and remifentanil cause adverse effects such as bradycardia and respiratory depression.Artificial ventilation is recommended when it’s administered in combination with general anesthetics.Due to the short duration of action of these drugs, analgesic supplementation after discontinuation of theinfusion is necessary to provide postoperative analgesia. The use of remifentanil may be advantageousover fentanyl in procedures requiring prolonged infusions, in patients with liver or kidney disease and for other occasions which require fast recovery from anesthesia, where as the disadvantage is the highcost compared to fentanyl.