Pleuropulmonary and cardiovascular consequences of thoracoscopy performed in healthy standing horses

Abstract

Six healthy, awake, and pharmacologically restrained mature horses were studied in order to define the changes in cardiopulmonary function during and after exploratory thoracoscopy and to determine the presence of postoperative complications occurring 48 hours after thoracoscopy. In a randomised 3 x 3 latin square design with 2 replications, 18 procedures were performed: 6 right (RTH) and 6 left thoracoscopies (LTH) and 6 sham procedures (STH). Prior to each procedure a physical examination and a bronchoalveolar lavage fluid analysis were performed. During thoracoscopy and sham protocols, horses were sedated with a continual drip of detomidine HCl and data were collected at 6 time intervals: T1 (baseline), T2 (10 min detomidine administration), T3 (first 15 min pneumothorax), T4 (5 min recovery from pneumothorax), T5 (second 15 min pneumothorax), and T6 (10 min recovery from the second pneumothorax and detomidine). An endoscopic thoracic examination was conducted during the 2 pneumothorax periods. An identical protocol was followed for sham procedures without surgery or pneumothorax. Data were analysed by ANOVA with time and surgical procedure as main factors. Physical examinations, thoracic radiography and ultrasound, CBC and bronchoalveolar lavage fluid analysis were performed 48 h after thoracoscopy. Heart rate, respiratory rate, and cardiac output decreased following detomidine administration. There was a trend for cardiac output to be lower during thoracoscopy. Mild systemic hypertension was associated with thoracoscopy although there was no effect on pulmonary arterial pressure. Total and pulmonary vascular resistances were increased following detomidine administration. Thoracoscopy caused a further increase in systemic and pulmonary vascular resistances especially during the second pneumothorax. Arterial O2 tension decreased following detomidine administration and was further decreased during the second pneumothorax period. PaO2 values were lower when thoracoscopy was performed on the left rather than the right hemithorax. No significant complications were found during the 48 h follow-up evaluation. A subclinical postoperative pneumothorax occurred in 2 horses, one of which had sustained a lung laceration by the trocar. Thoracoscopy performed in healthy, awake, and pharmacologically restrained horses did not have detrimental cardiopulmonary effects and did not cause postoperative complications within the first 48 h period.

Avaliação dos efeitos do pneumotórax unilateral de baixa pressão induzido em eqüinos

“…Em eqüinos, a toracoscopia tem sido utilizada para colocação de drenos torácicos em casos de abscessos e de lojas intrapleurais contendo líquido, no controle da eficácia da lavagem pleural, e na avaliação da progressão e A toracoscopia é procedimento bem tolerado por cavalos submetidos à sedação com agentes alfa-2 agonistas (PERONI et al, 2001;PERONI et al, 2000;VACHON;FISCHER, 1998) ou com a associação de alfa-2 agonista com agentes opióides (LUGO et al, 2002;ZOPPA, 2003;ZOPPA et al, 2001) juntamente com a infiltração de anestésico local no ponto de inserção do trocarte.…”

“…O pneumotórax é induzido após a perfuração da parede torácica, e as estruturas anatômicas da cavidade em questão podem ser observadas após o colapso do pulmão ipsilateral (PERONI et al, 2000).…”

“…A técnica de toracoscopia foi primeiramente descrita em 1910 por um médico sueco chamado Jacobeus, que utilizou um cistoscópio para visualizar o espaço pleural em humanos (BRAIMBRIDGE, 1993;KLOHNEN;PERONI, 2000). Para Ginsberg (1993) e Lugo et al (2002), os benefícios da toracoscopia sobre a toracotomia incluem melhora na visualização e diminuição da dor, diminuição do período de internação do paciente e da morbidade no período pós-operatório.…”

“…O pulmão colabado, a aorta, esôfago e diafragma foram identificados por Peroni et al (2001) KUDNIG et al, 2004;PERONI et al, 2000).…”

“…Uma das causas atribuídas à diminuição do débito cardíaco é a ausência da pressão pleural negativa e o colapso pulmonar, reduzindo o retorno venoso para o coração durante o pneumotórax suprimindo a função "bombeadora" do tórax (PERONI et al, 2000 GOOSSENS, 1991;FANTONI et al, 1999;GEISER, 1990 (GEISER, 1990;HEEL et al,1978;KALPRAVIDH et al, 1984b Quando utilizado na dose de 0,22 mg/kg, o butorfanol promove boa analgesia para dor visceral e analgesia inconsistente para dor superficial (KALPRAVIDH et al, 1984b). Os efeitos colaterais são, quando o fármaco é utilizado nesta dose, ataxia, agitação e tremores musculares (KALPRAVIDH et al, 1984a).…”