RESUMO Objetivou-se avaliar os efeitos fisiológicos e sobre o consumo do propofol, relativos à anestesia epidural com levobupivacaína isolada ou associada a diferentes doses de tramadol. Para tal, 18 cadelas foram pré-tratadas com acepromazina, utilizando-se propofol para indução e manutenção anestésicas. Conforme o protocolo epidural instituído, formaram-se três grupos (n=6) tratados com levobupivacaína isolada (1,5mg/kg) (GL) ou acrescida de 2mg/kg (GLT2) ou 4mg/kg (GLT4) de tramadol, respectivamente. As fêmeas foram submetidas à mastectomia e à ovário-histerectomia (OH), registrando-se as variáveis fisiológicas nos períodos pré (TB e T0) e transanestésicos (T10 a T70), bem como a taxa mínima de propofol necessária. Houve redução da FC para o GL e o GLT4 em relação ao GLT2 (T30 a T70), detectando-se, no GL, redução da PAS e da PAD em relação ao TB. Maiores taxas de infusão do propofol foram necessárias para o GL (0,70±0,12mg/kg/min) em relação ao GLT2 (0,50±0,19mg/kg/min) e ao GLT4 (0,50±0,19mg/kg/min). Conclui-se que o tramadol potencializou o propofol, ao ofertar analgesia, independentemente da dose administrada. Todos os protocolos testados foram seguros e eficazes em cadelas submetidas à mastectomia e à OH.

Polycythaemia vera is a common haematological proliferative disorder. It is characterised by uncontrolled red cell production with ensuing peri-operative vaso-occlusive and haemorrhagic complications. Spinal haematoma after neuraxial anaesthesia is rare; most cases are associated with technical difficulties or bleeding disorders. Current consensus opinion suggests that neuraxial anaesthesia in patients with polycythaemia vera is safe due to a lower risk of thrombotic events and hypoxaemia compared with general anaesthesia. We report a case of a spinal subarachnoid haematoma after uneventful neuraxial anaesthesia in a patient with optimised polycythaemia vera. Despite an emergent laminectomy, the patient developed permanent motor deficits. This report highlights that although neuraxial anaesthesia is recommended by many authors, patients with polycythaemia vera can paradoxically have an increased haemorrhagic risk from platelet dysfunction and acquired von Willebrand disease. Clinicians proceeding with surgery under neuraxial anaesthesia should appreciate these risks even in patients with normal or apparently elevated thrombotic states. This case also demonstrates that traditional coagulation tests may need to be complemented by pre-operative platelet function tests and screening for von Willebrand disease. Finally, the importance of the patient participation in the choice of the anaesthesia technique cannot be understated, with specific attention paid to this frequently unrecognised risk.