An ultrasound-guided two-point transversus thoracic plane block for canine sternotomy.

We describe a two-point ultrasound-guided transversus thoracic plane (TTP) block in a 10 year old entire female Shih Tzu, weighing 8.5 kg, and undergoing sternotomy for thymoma removal. Thymoma was an incidental finding observed during preanaesthetic radiographs prior to dental cleaning. The dog did not present clinical signs and no notable alterations were found in her physical examination or blood analyses, so she was assigned an American Society of Anesthesiologists status score of II. After cannulation of both saphenous veins (intravenous catheter; Covetrus, The Netherlands), methadone (0.2 mg kg–1; Semfortan; Dechra, Spain) and dexmedetomidine (0.001 mg kg–1; Dexdomitor; Ecuphar, Spain) were administered intravenously (IV). After 5 minutes of preoxygenation by facemask (B. Braun Medical SA, Spain), anaesthesia was induced and maintained with propofol (2 mg kg–1 followed by 0.3 mg kg–1 minute–1, Propomitor; Ecuphar). Immediately after tracheal intubation, pressure-controlled mechanical ventilation was started [peak inspiratory pressure 8 cmH2O; respiratory rate was adjusted to maintain the end-expiratory carbon dioxide pressure (Pe′CO2) between 35 and 45 mmHg (4.7–6 kPa); 9100c NXT; GE Healthcare GmbH, Germany] and a 1:1 mixture of oxygen and air was administered using a rebreathing system (circle circuit; Intersurgical Ltd, UK). Arterial blood pressure was measured using oscillometry as arterial catheter placement was unsuccessful. The cuff (4.3–8 cm; Dräger, Spain) was placed over the left dorsal pedal artery. Oesophageal temperature, electrocardiogram, haemoglobin oxygen saturation and respiratory gases were monitored during the procedure using a multiparametric anaesthetic monitor (9100c NXT; GE Healthcare GmbH). Variables were recorded every 2 minutes and reported as median (range). Lactated Ringer’s solution (5 mL kg–1 hour–1; Ringer lactate; B. Braun VetCare SA, Spain) was administered during anaesthesia.