Comparison of left fourth and fifth intercostal space thoracotomy for open‐chest cardiopulmonary resuscitation in dogs

OBJECTIVE: To determine whether ease of access to thoracic structures for performing open‐chest cardiopulmonary resuscitation (OC‐CPR) differed between fourth and fifth intercostal space (ICS) left lateral thoracotomies in dogs, and to determine if “shingling” improved access for OC‐CPR manipulations. DESIGN: Prospective single‐blinded study. SETTING: Laboratory. ANIMALS: Twelve mixed breed canine cadavers weighing approximately 20 kg. INTERVENTIONS: Left lateral thoracotomies were performed at the 4th ICS (n = 6) or 5th ICS (n = 6). Shingling at the 4th or 5th ICS, as applicable, was performed after initial data collection and outcomes were reassessed. MEASUREMENTS AND MAIN RESULTS: Three evaluators blinded to the surgical approach scored the following parameters on a 0 to 10 scale (0 = easiest, 10 = most difficult): ease of access of the phrenicopericardial ligament, ease of pericardial incision, ease of appropriate hand position, ease of aortic access, ease of Rumel tourniquet application, and ease of proper placement of defibrillation paddles. Objective measurements (time to completion or number of attempts) were made for all but ease of pericardial incision and ease of appropriate hand position. Outcomes were reassessed after shingling. The 5th ICS was superior for ease of aortic access (P = 0.042), time to visualization of aorta (P = 0.009), and ease of application of a Rumel tourniquet (P = 0.019). When comparing scores pre‐ and post‐shingling, shingling improved time to visualization of the aorta (P < 0.001), time to placement of Rumel tourniquet (P < 0.001), ease of paddle placement (P = 0.017), and time to paddle placement (P < 0.001). CONCLUSIONS: Either 4th or 5th ICS thoracotomy may provide adequate access to intrathoracic structures pertinent to performing OC‐CPR in dogs weighing approximately 20 kg, but 5th ICS was preferred for most manipulations, and shingling improved access for most of the measured parameters.