Anaesthetic management of a patient undergoing dental extractions with concurrent congestive heart failure and advanced tracheal collapse

The patient was presented to the hospital for routine examination with a history of congestive heart failure (CHF) and advanced tracheal collapse. The owner reported recent exacerbation of the patient's chronic cough; the cough was described as intermittent and dry. Physical examination confirmed a systolic II/VI grade heart murmur, identified severe periodontal disease and an irritable trachea. The veterinary surgeon suspected that periodontal disease was a contributing factor in the exacerbation of the patient's chronic cough and development of tracheobronchitis, as a consequence of bacterial transfer from the oral cavity (Pardali et al, 2010). The patient was admitted to the hospital for dental prophylaxis and extractions under general anaesthesia.

The patient was receiving pimobendan (Vetmedin, Boehringer Ingelheim Limited) 0.3 mg/kg every 12 hours orally and furosemide (Frusemide, Millpledge Veterinary) 2.5 mg/kg every 12 hours orally for CHF. Pimobendan is an oral inodilator with phosphodiesterase III inhibition, which decreases the breakdown of cyclic adenosine monophosphate (Atkinson, 2009). As a result pimobendan increases cardiac sensitivity to calcium, cardiac contractibility and relaxation, and potentiates arterial and veno-dilatation (Fuentes, 2004), which may exacerbate the hypotensive effects of anaesthetic agents. Furosemide, a loop diuretic, promotes sodium excretion and increases urine output (Smith, 2006), which decreases intravascular volume and preload venous pressure, thereby reducing pulmonary oedema and congestion (Erling and Mazzaferro, 2008). Diuretic use, in conjunction with anaesthetic agents, can promote hypovolaemia, electrolyte imbalance and increase incidence of peri-operative arrhythmia (Groban and Butterworth, 2006).