Experimentally Induced Open Pneumothorax in Horses.

The objective of this study was to evaluate clinical and cardiovascular parameters and pleural and intra-abdominal pressures of horses after experimentally induced unilateral open pneumothorax. Prospective, experimental study-animals: seven healthy adult horses, 4 females and 3 males. Left hemithorax thoracotomy was carried out to create an open pneumothorax for 60 minutes. Pleural pressure (Ppl) was directly obtained at the midpoint of the left eighth intercostal space before thoracotomy. Esophageal pressure (Pes), arterial blood gas analysis, left ventricular function, and ultrasonographic assessment of pneumothorax extent/resolution were performed at the baseline, and 5, 10, 15, 30, 45, and 60 minutes after thoracotomy, and on the first, second, third, fifth, and seventh days postoperatively. Intra-abdominal pressure was only recorded while the pneumothorax was present. There was moderate correlation (Spearman's rs = 0.404; R2 = 0.8; P < .00001; Bland-Altman bias = -2.59; s.d. = 2.11) between Pes and Ppl. Esophageal pressure increased (P < .05) after open pneumothorax until the fifth day postoperatively. Partial pressure of oxygen in arterial blood reduced (P < .05) until the third day postoperatively when it returned to the baseline. No significant variations in PaCO2, pH in arterial blood, and in left ventricular function were appreciated. The extent of the pneumothorax was assessed by thoracic ultrasonography. Esophageal pressure, in association with blood gas analysis and thoracic ultrasonography, could be used to aid diagnosis of pneumothorax in horses. Horses tolerate open pneumothorax, with minimum cardiovascular impairment, even without aspiration of free air from within pleural space to restore thoracic wall integrity.

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)

Effects of butorphanol on the minimum anesthetic concentration for sevoflurane in guineafowl (Numida meleagris).

OBJECTIVE: To determine the minimum anesthetic concentration (MAC) for sevoflurane and measure the dose and temporal effects of butorphanol on the MAC for sevoflurane in guineafowl. ANIMALS: 10 healthy adult guineafowl (Numida meleagris). PROCEDURES: Each bird was anesthetized with sevoflurane, and a standard bracketing method was used to measure the MAC in response to a noxious electrical stimulus. Subsequently, conditions were adjusted so that each bird was anesthetized with sevoflurane at a fraction of its respective MAC (eg, 0.7 times the MAC for that bird). Butorphanol tartrate (2 mg/kg, IV) was administered, and a noxious stimulus was applied every 15 minutes until the bird moved in response. The reduction in MAC was estimated with logistic regression by use of a standard quantal method. After an interval of ≥ 1 week, the MAC reduction experiment was repeated with an increased butorphanol dosage (4 mg/kg). RESULTS: Individual mean ± SE MAC for sevoflurane was 2.9 ± 0.1%. At 15 minutes after administration of 2 mg of butorphanol/kg, estimated reduction in the MAC for sevoflurane was 9 ± 3%. At 15 and 30 minutes after administration of 4 mg of butorphanol/kg, estimated reduction in the MAC for sevoflurane was 21 ± 4% and 11 ± 8%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: In guineafowl, the MAC for sevoflurane was similar to values reported for other species. Increasing the butorphanol dosage decreased the MAC for sevoflurane, but the effect was small and of short duration for dosages up to 4 mg/kg.