Increases of heart rate and systolic blood pressure in anaesthetized dogs affected with X-linked muscular dystrophy after cis-atracurium administration: a case series report

The anesthesia records (n = 30) of 5 experimental male dogs affected with Duchenne Muscular Dystrophy (DMD) that periodically underwent general anaesthesia for magnetic resonance imaging (MRI) studies of the heart were retrospectively reviewed. General anaesthesia was induced in all dogs with an intravenous (IV) administration of fentanyl (range; 0.010 – 0.012 mg kg-1) followed by propofol (3 – 4 mg kg-1). After orotracheal intubation all dogs’ lungs were mechanically ventilated with 100% oxygen. General anaesthesia was maintained with a constant rate infusion of propofol (0.1 – 0.2 mg kg-1 min-1) and fentanyl (0.5 – 0.7 mg kg-1 min-1) titrated to maintain an adequate level of anaesthesia. A continuous lead II ECG; heart rate (HR); systolic (SAP), diastolic, and mean arterial pressures, haemoglobin oxygen saturation, respiratory rate and end-tidal CO2 were recorded measure continuously and recorded every 5 minutes throughout anaesthesia. In order to improve the quality of the thoracic images, a 2 min-long apnea was induced was induced with a IV bolus of cisatracurium (0.1 mg kg-1) and by discontinuing mechanical ventilation. Immediately after the administration of cisatracurium, an increase of HR and SAP was observed in all dogs, with a mean (SD) percentage and absolute increase of 115.4 ± 64.9% and 78.3 ± 37.0 beats/min and 33.5 ± 31.2 % and 33.0 ± 28.3 mmHg, respectively. No other major cardiovascular or respiratory changes were observed. All dogs recovered from general anaesthesia without complications. Reactions to general anesthesia, including a high sensibility to selected non-depolarizing neuromuscual blockers, have been reported for human patients affected with DMD. To our knowledge, this is the first report of increases in HR and SAP related to the administration of cis-atracurium in either human or animal patients affected with DMD. This cardiovascular changes in DMD patients deserve further investigation.