Assessment of thermal response, cardiorespiratory parameters and post-operative analgesia in dogs undergoing ovariohysterectomy with different combinations of epidural analgesia and isoflurane

This study aimed to evaluate the thermal response of the eyelids and lacrimal gland of the left eye (LETG) through infrared thermography (IRT), cardiorespiratory parameters, and their association with nociception and pain in bitches undergoing elective ovariohysterectomy (OVH) anesthetized with isoflurane and epidural analgesia. Twenty-one healthy bitches of different breeds were randomized into three groups receiving epidural blocks: GL (n=7), lidocaine (2 mg Kg-1 ); GLF (n=7), lidocaine (2 mg Kg-1 ) and fentanyl (3 µg Kg-1 ); and GLM (n=7), lidocaine (2 mg Kg-1 ) with morphine (0.1 mg Kg-1 ). IRT and cardiorespiratory parameters were evaluated at baseline (Ebasal), thirty minutes before anesthetic premedication, and at different surgical events: first incision (EInc), ligature and section of the left (ELoV), and right (ERoV) ovarian pedicle, ligature, and re-section of the cervix (EUt), and skin suture (ESut). The assessment of acute pain in the immediate post-operative period was registered at E1h, E2h, and E3h using IRT, the Dynamic Interactive Visual Analogic Scale (DIVAS), and the University of Melbourne Pain Scale (UMPS) scales. The results showed a statistically significant decrease in the lower eyelid surface temperature (LELT) during EInc for GL (32.9°C ± 0.62), in comparison to GLF (34.2°C ± 0.62) and GLM (35.3°C ± 0.62) (P = 0.006). Regarding LETG, a significant increase (P = 0.03) in the IRT of Ebasal (36.8°C ± 0.63) and EInc (36.1°C ± 0.63) for GLM was observed in comparison to the thermographic values for both perioperative events and groups. The GLM showed a significant decrease in IRT values of ERoV at E3h in the upper and lower eyelids (P = 0.03 and P = 0.01, respectively). A progressive and significant reduction of the IRT values of LETG was also recorded in GLM, with differences in ERoV (35.2 °C ± 0.63) (P = 0.02) and E3h (35.3 °C ± 0.63) (P = 0.01). The cardiovascular parameters (SAP, DAP, and MAP) did not differ between treatments, but in GL, there was a significant difference (P = 0.01) during EInc and ESut, compared to Ebasal. In the body temperature, EInc and ESut gradually decreased in all treatment groups (P = 0.01). In conclusion, hemodynamic and cardiorespiratory stability was associated with IRT readings and the absence of nociception. Changes in superficial temperature in the immediate post-operative period were lessened using isoflurane and epidural analgesia of lidocaine alone or in combination with pure opioids. These findings were clinically validated to the DIVAS and UMPS acute pain assessment scales.

Anestesia regional intravenosa (bloqueio de Bier) em urubu-de-cabeça-preta (Coragyps atratus) submetido à amputação de dígito / Regional intravenous anaesthesia (Bier's block) in black-headed vulture (Coragyps atratus) submitted to digit amputation

Background: The Coragyps atratus flies long distances in search of food and has a marked behaviour of food competition. Since they are frequently found in areas of recent human occupation, they are subject to trauma, which may require surgical interventions. Locoregional blocks are used as part of a balanced-anaesthesia protocol and are currently being evaluated in birds, with brachial plexus block being the main technique described in the literature. However, to our knowledge, this is the first description of intravenous regional anaesthesia (Bier's block) in a vulture. Thus, we aim to report the use of Bier's block with 1% lidocaine, in a black-headed vulture submitted to digit amputation. Case: A black-headed vulture (Coragyps atratus), weighing 2 kg, was rescued and referred to the Veterinary Hospital due to its inability to fly. Physical examination revealed a swollen digit in the right pelvic limb. Radiographic examination confirmed the intermediate phalanx fracture of the 4th digit of the right pelvic limb with signs suggestive of advanced osteomyelitis. The animal was referred to surgery for amputation of the affected digit. Before surgery, water and food were withdrawn for 12 h. Pre-anaesthetic medication consisted of 1 mg/kg midazolam and 0.5 mg/kg morphine intramuscularly (IM). Anaesthetic induction was performed through face mask with isoflurane, followed by orotracheal intubation with a 3 mm-endotracheal tube. Anaesthesia was maintained with isoflurane through a non-rebreathing circuit in 100% oxygen. Using a multiparametric monitor, heart rate (HR), respiratory rate (RR), end-tidal CO2 (EtCO2 ), oxyhemoglobin saturation (SpO2 ), electrocardiography (ECG), systolic blood pressure (SBP) and core temperature (CT) were evaluated. Antisepsis of the right pelvic limb was performed and an elastic band was applied around the distal region of the affected tibia to serve as a tourniquet. A scalp vein set was used to access the lateral saphenous vein in the region distal to the tourniquet, and 5 mg/ kg lidocaine 1% was injected intravenously. The patient remained stable during the procedure, with no need for analgesic rescue. The tourniquet was gradually released 40 min past its application, being completely removed after 45 min of surgery. The anaesthetic supply was interrupted, with extubation after 4 min; the patient had satisfactory anaesthetic recovery. Discussion: The present report describes the success in using the technique of intravenous regional anaesthesia with 1% lidocaine for digit amputation performed on a specimen of black-headed vulture. The pre-anaesthetic medication provided analgesia, satisfactory sedation for venoclysis, and anaesthetic induction without complications. Anaesthetic induction and maintenance in birds are preferably performed with inhaled anaesthetics, thus the choice of mask induction. Despite the reduction in RR soon after induction, the patient remained on spontaneous ventilation. Bier's block using 5 mg/kg lidocaine showed to be an easy and safe technique in vultures, but doses up to 6 mg/kg lidocaine are not associated with adverse effects in birds. The intravenous regional anaesthesia technique described in this manuscript promoted adequate analgesia for the digit amputation procedure in black-headed vultures and allowed hemodynamic stability without significant anaesthetic complications. Thus, the present report points to the potential use of this locoregional block in other birds.

Effects of heated tumescence solution in bitches after unilateral mastectomy

Background: Mammary tumors, for which mastectomy is the main treatment, are the most common neoplasms in bitches. Mastectomy is painful and, in order to reduce the pain stimulus in the transoperative period, tumescent local anesthesia is associated with general inhalation anesthesia. However, despite the numerous benefits of tumescence, intraoperative hypothermia is the most common complication. In Medicine, especially in plastic and dermatological surgery, it is common to use a heated tumescence solution to prevent intraoperative hypothermia; however, in Veterinary medicine, no previous study has examined the advantages and disadvantages of using heated tumescence solution. Thus, this study aimed to investigate the transanesthetic cardiorespiratory effects of heated tumescence solution in bitches submitted to radical unilateral mastectomy. Materials, Methods & Results: Eight animals were treated with 0.1% lidocaine solution, warmed to 37-42°C, using a Klein’s cannula for administration. Chlorpromazine (0.3 mg/kg) and meperidine (3 mg/kg) were used as pre-anesthetic medication intramuscularly, and induction was performed with intravenous propofol and maintenance with isoflurane. The data collection times were as follows: 15 min after starting isoflurane administration (M1), 5 min after tumescence (M2), after beginning of surgical incision (M3), during breast pullout (M4), after clamping of the superficial caudal epigastric vein, and artery (M5), after the beginning of the approximation of the subcutaneous tissue (M6), after the beginning of the intradermal suture (M7), and at the end of the surgical procedure (Mfinal). The heart...

Effects of heated tumescence solution in bitches after unilateral mastectomy

Background: Mammary tumors, for which mastectomy is the main treatment, are the most common neoplasms in bitches. Mastectomy is painful and, in order to reduce the pain stimulus in the transoperative period, tumescent local anesthesia is associated with general inhalation anesthesia. However, despite the numerous benefits of tumescence, intraoperative hypothermia is the most common complication. In Medicine, especially in plastic and dermatological surgery, it is common to use a heated tumescence solution to prevent intraoperative hypothermia; however, in Veterinary medicine, no previous study has examined the advantages and disadvantages of using heated tumescence solution. Thus, this study aimed to investigate the transanesthetic cardiorespiratory effects of heated tumescence solution in bitches submitted to radical unilateral mastectomy. Materials, Methods & Results: Eight animals were treated with 0.1% lidocaine solution, warmed to 37-42°C, using a Kleins cannula for administration. Chlorpromazine (0.3 mg/kg) and meperidine (3 mg/kg) were used as pre-anesthetic medication intramuscularly, and induction was performed with intravenous propofol and maintenance with isoflurane. The data collection times were as follows: 15 min after starting isoflurane administration (M1), 5 min after tumescence (M2), after beginning of surgical incision (M3), during breast pullout (M4), after clamping of the superficial caudal epigastric vein, and artery (M5), after the beginning of the approximation of the subcutaneous tissue (M6), after the beginning of the intradermal suture (M7), and at the end of the surgical procedure (Mfinal). The heart...(AU)

Management of urethral obstruction in a cat with epidural sacrococcygeal anesthesia guided by electrical neurostimulation

Background: The treatment for urethral obstruction in cats consists of catheterization, and for this, the cat must be sedated or anesthetized. Sacococcygeal epidural block has the advantage of being close to receptors related to nociception located in the spinal cord and it is safer because it represents lower risk of spinal cord injury or inadvertent application in the subarachnoid space, when compared to the lumbosacral epidural. Nerve stimulation through the neurolocator to identify the epidural space increases the accuracy of this technique. Thus, the objective is to report a case of epidural anesthesia with a sacrococcygeal approach guided by neurostimulation in a cat with urethral obstruction. Case: A 4-year-old male Siamese cat, weighing 4 kg, was referred to the veterinary care with a history of apathy and anorexia for 2 days. From the physical exam, the clinical diagnosis of urethral obstruction was made, and to desobstruction, we chose to perform sacrococcygeal epidural block. Initially, the patient was anesthetized with propofol (4 mg/kg) and midazolam (0.3 mg/kg). To perform the anesthetic block, the cat was placed in sternal decubitus with the hind limbs extended cranially to perform sacrococcygeal epidural block. The positive pole (cathode) was connected to the skin of the right inguinal region at the caudal aspect of the thigh and the neurostimulator was turned on and adjusted to 0.7 mA of stimulating current intensity, 0.1 ms duration and 1 Hz frequency. The needle for electrical neurolocation was introduced in the dorsal midline, perpendicular to the skin surface, between the spinous processes of S3-Cd1 in the skin. The exact injection point was obtained observed by the muscular response of the middle and distal third of the animal's tail with the neurostimulator adjusted to 0.3 mA of intensity, in the same duration and frequency as before. The total volume of 0.9 mL (0.22 mL/kg) of solution containing the combination of 0.6 mL of 0.75% levobupivacaine and 0.3 mL of 2% lidocaine was injected. The success of the block was confirmed by the loss of reflexes of the pelvic limbs and anal sphincter 10 min after the administration of the anesthetic solution. Discussion: In this case, the use of the neurolocator helped to perform an effective sacrococcygeal block, allowing urethral catheterization without the addition of other analgesic agents. This technique desensitizes and relaxes muscles in the regions of the perineum, anus, distal colon and penis, being useful for performing urethral catheterization. The use of smaller anaesthetic volumes to perform sacrococcygeal block makes it possible to achieve a more localized anesthesia, without affecting the motor function of the pelvic limbs. However, in our report, using a combination of levobupivacaine and lidocaine, the pelvic limb block was also verified despite the low volume applied. A hypothesis that could justify the different responses in relation to the pelvic limb block compared to other studies would be due to the different physicalchemical properties of the drugs used. Lidocaine is known to be less fat-soluble than bupivacaine, so it tends to spread more through the epidural space, in order to result in more extensive blocks. The use of a neurostimulator using a fixed electric current of 0.7 mA, pulse 0.1 ms and a frequency of 1 Hz allowed the correct identification of the needle position for the application of the anesthetic.

Topical application of lidocaine or bupivacaine in the healing of surgical wounds in dogs

Purpose: To analyze the anesthetic drugs interference with wound healing when used in the surgical bed. Methods: Macro and microscopic aspects of healing of surgical wounds were evaluated after instillation of topical anesthetics without vasoconstrictor or saline solution 0.9% as control in the transsurgical period. Thirty dogs, males and females were divided into two experimental groups. In both groups, two circular punch lesions of 6 mm diameter were performed in the abdomen. In group 1, lidocaine was instilled in one of the lesions and saline solution in the contralateral lesion. In group 2 the procedure was repeated with the use of bupivacaine. The macroscopic assessment of the lesions was performed on the first, third and tenth postoperative day. The excisional biopsy was performed on the tenth day and the samples were submitted for histopathological examination. Results: The macroscopic analysis had a significant difference between groups. Microscopic analysis was not significant between groups. Conclusions: The topical application of lidocaine and bupivacaine in the surgical wound is feasible and it does not influence skin healing. The benefit of such a practice, which has been the subject of other studies, seems to outweigh the risks.(AU)

Evaluation of postoperative residual analgesia of two solutions used for local anesthesia by tumescence in bitches who underwent a unilateral mastectomy / Avaliação da analgesia residual pós-operatória de duas soluções utilizadas para anestesia local por tumescência em cadelas submetidas à mastectomia unilateral

Background: Breast tumors are common and require surgical treatment. A mastectomy causes edema, inflammation, and moderate to severe pain; therefore, analgesics should be used efficiently during the trans and postoperative periods. Tumescence anesthesia has been studied in veterinary medicine; however, there is limited literature on the comparison of the constituents of the different solutions and the most suitable protocol. The objective of this study was to evaluate the residual postoperative analgesia of two solutions through the Melbourne, Modified Glasgow for dogs (EGM), and Visual Analogue (EVA) scales in bitches who underwent a unilateral mastectomy.Materials, Methods & Results: Twelve bitches, weighing between 5 and 15 kg and aged between 5 and 13 years old, were included in the study. To determine if the animals were medically fit to undergo the procedure, they were evaluated by clinical examination, laboratory testing (complete blood count, serum biochemistry [urea, creatinine and alanine aminotransferase/ALT], and imaging (thorax x-ray and abdominal ultrasonography). Patients were randomly divided into two groups. One group received a lidocaine-containing tumescent solution (GTL) that consisted of 210 mL of lactated Ringer’s solution (at a temperature between 8 and 12°C), 40 mL of 2% lidocaine hydrochloride without vasoconstrictor, and 0.5 mL of adrenaline (1 mg/mL). The other group received ropivacaine (GTR) with 233.3 mL of lactated Ringer’s solution (at the same temperature as the previous group’s), 16.7 mL of ropivacaine (7.5 mg/mL), and 0.5 mL of adrenaline (1 mg/mL). Both groups received a combination of acepromazine (0.04 mg/kg) and meperidine (2 mg/kg) as preanesthetic medication (MPA), followed by induction using propofol (to effect) and maintenance using isoflurane. The solutions were infused subcutaneously (SC) 5 min after stabilization of the anesthetic plane.[...]

Evaluation of postoperative residual analgesia of two solutions used for local anesthesia by tumescence in bitches who underwent a unilateral mastectomy / Avaliação da analgesia residual pós-operatória de duas soluções utilizadas para anestesia local por tumescência em cadelas submetidas à mastectomia unilateral

Background: Breast tumors are common and require surgical treatment. A mastectomy causes edema, inflammation, and moderate to severe pain; therefore, analgesics should be used efficiently during the trans and postoperative periods. Tumescence anesthesia has been studied in veterinary medicine; however, there is limited literature on the comparison of the constituents of the different solutions and the most suitable protocol. The objective of this study was to evaluate the residual postoperative analgesia of two solutions through the Melbourne, Modified Glasgow for dogs (EGM), and Visual Analogue (EVA) scales in bitches who underwent a unilateral mastectomy.Materials, Methods & Results: Twelve bitches, weighing between 5 and 15 kg and aged between 5 and 13 years old, were included in the study. To determine if the animals were medically fit to undergo the procedure, they were evaluated by clinical examination, laboratory testing (complete blood count, serum biochemistry [urea, creatinine and alanine aminotransferase/ALT], and imaging (thorax x-ray and abdominal ultrasonography). Patients were randomly divided into two groups. One group received a lidocaine-containing tumescent solution (GTL) that consisted of 210 mL of lactated Ringers solution (at a temperature between 8 and 12°C), 40 mL of 2% lidocaine hydrochloride without vasoconstrictor, and 0.5 mL of adrenaline (1 mg/mL). The other group received ropivacaine (GTR) with 233.3 mL of lactated Ringers solution (at the same temperature as the previous groups), 16.7 mL of ropivacaine (7.5 mg/mL), and 0.5 mL of adrenaline (1 mg/mL). Both groups received a combination of acepromazine (0.04 mg/kg) and meperidine (2 mg/kg) as preanesthetic medication (MPA), followed by induction using propofol (to effect) and maintenance using isoflurane. The solutions were infused subcutaneously (SC) 5 min after stabilization of the anesthetic plane.[...](AU)

A study on reducing the absorption of lidocaine from the airway in cats

Purpose: To determine if the combination of lidocaine with epinephrine or gamma globulin would decrease the rate or reduce the amount of local absorption of lidocaine through the airway. Methods: Twenty adult male cats were randomly and evenly distributed into four groups: 1) Group LG: lidocaine administered with gamma globulin; 2) Group LS: lidocaine administered with physiological saline); 3) Group LE: lidocaine administered with epinephrine; 4) Group C: control group. Invasive blood pressure, heart rate, and concentration of lidocaine were recorded before and after administration. Results: The peak of plasma concentrations appeared difference (Group LG: 1.39 ± 0.23 mg/L; Group LS: 1.47 ± 0.29 mg/L and Group LE: 0.99 ± 0.08 mg/L). Compared to Group C, there were significant differences in the average heart rate of Groups LG, LS, and LE (P 0.05). The average systolic blood pressures were significantly different when each group was compared to Group C (P 0.05). The biological half-life, AUC0-120, peak time, and half-life of absorption among the three groups have not presented statistically significant differences (P > 0.05). Conclusion: Administering lidocaine in combination with gamma globulin through airway causes significant decrease the rate and reduce the amount of local absorption of lidocaine in cats.(AU)

Comparison of continuous intravenous infusion of tramadol and tramadol-lidocaine-ketamine in the sevoflurane requirement in dogs / Comparação da infusão continua intravenosa de tramadol e de tramadol-lidocaína-cetamina no requerimento de sevofluorano em cães

The objective of this study was to compare the influence of continuous intravenous infusion of tramadol alone, or tramadol combined with lidocaine and ketamine, on minimum alveolar concentration of sevoflurane (MACsevo) of dogs undergoing an ovariohysterectomy (OHE). We used 28 healthy dogs of various breeds and age, randomly divided into two groups according to the infusion given: TRA (tramadol alone) or TLK (tramadol, lidocaine and ketamine). The patients were premedicated with acepromazine and midazolam, and then anesthesia was induced with propofol and maintained with sevoflurane. Fifteen minutes after induction, the patients received their loading dose of treatment. Then, the continuous infusion was then set to 1.3mg/kg/hour of tramadol with or without 3mg/kg/hour of lidocaine and 0.6mg/kg/hour of ketamine, diluted in a 500mL bag of saline solution at an infusion rate of 10mL/kg/hour. The Dixon method was chosen to determine the MACsevo and a skin incision was used as a noxious stimulus. An unpaired Student's t-test was used to identify statistically significant differences between the treatments. These differences were considered significant when p<0.05. The MACsevo of the TRA group was 1.22±0.15 vol% and the MACsevo of the TLK group was 0.85±0.22 vol%. We conclude that TLK infusion decreased the MACsevo by 30.22% compared to tramadol alone, demonstrating that the combination of drugs was effective in reducing MACsevo in dogs.(AU)

O objetivo deste estudo foi comparar a influência da infusão contínua intravenosa do tramadol isolado e associado com lidocaína e cetamina, na concentração alveolar mínima de sevofluorano (CAMsevo) em cadelas submetidas à ovariosalpingohisterectomia. Foram utilizados 28 animais saudáveis de várias raças e idades, divididos aleatoriamente em dois grupos de acordo com a infusão adminstrada: TRA (tramadol) ou TLK (tramadol, lidocaína e cetamina). A medicação pré-anestésica foi realizada com acepromazina e midazolam, em seguida, a anestesia foi induzida com propofol e mantida com sevofluorano. Quinze minutos após a indução, os pacientes receberam um bolus do tratamento, com a infusão continua iniciada logo em seguida, sendo 1,3mg/kg/hora de tramadol, associado ou não a 3mg/kg/hora de lidocaína e 0,6mg/kg/hora de cetamina, diluidos em uma bolsa de solução salina de 500mL a uma taxa de infusão taxa de 10ml/kg/hora. O método de Dixon foi escolhido para determinar a MACsevo e a incisão na pele foi utilizada como o estímulo nocivo. O teste t de Student não pareado foi utilizado para identificar diferenças estatisticamente significativas entre os tratamentos. Estas diferenças foram consideradas significativas quando p<0,05. A CAMsevo do grupo TRA foi de 1,22±0,15vol% e a CAMsevo do grupo TLK foi de 0,85±0,22vol%. Conclui-se que a infusão de TLK diminuiu a CAMsevo em 30,22% em relação ao tramadol isolado, o que demonstra que a combinação de agentes analgésicos foi eficaz na redução do requerimento de sevofluorano em cães.(AU)