LAUSR

We read with interest the well written and thorough study by Helgestad et al.1 describing temporal trends and the characteristics of acute myocardial infarction complicated by cardiogenic shock based on data from the Danish Heart Failure Registry. There are several important findings in this study,1 perhaps most notably the lack of change in 30-day mortality rates of ∼50% from 2010 to 2017. Although numerous initiatives are underway to improve outcomes,2 clinicians and researchers are left asking how we can improve outcomes in this critically ill population. Although advances are likely to include multiple interventions, one crucial but poorly researched aspect of the care of patients with cardiogenic shock is the management of respiratory support. In their study, Helgestad et al.1 noted an increase in the use of mechanical ventilation over the study period with over 85% of patients requiring ventilatory support by 2017. However, many questions remain, including specific details regarding the use of respiratory support in the other 15% of patients (e.g. non-invasive ventilation), the aetiology of intubation (e.g. hypoxic respiratory failure, airway protection, etc.), and how respiratory support strategies may have influenced outcomes. Perhaps as a result of the perception that mechanical ventilation is often temporary, it has not garnered much attention from the cardiovascular community despite the intimate cardiopulmonary relationship between positive pressure ventilation and both left and right ventricular function.3 In addition to significant haemodynamic effects from alterations in both preload and afterload, mechanical ventilation carries potentially deleterious effects such as infection, hyperoxaemia and ventilator-induced lung injury.3 Although best described in acute respiratory distress syndrome, ventilator-induced lung injury and the subsequent proinflammatory state may also occur in uninjured lungs and potentially contribute to multiple system .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. organ dysfunction.4 Given the proinflammatory cascade associated with the cardiogenic shock spiral,5 we would suggest that mechanical ventilation as a mediator of inflammation deserves further consideration in this patient population. Many important questions remain to be answered in order to improve cardiogenic shock outcomes. Given the frequency of its use and its unique effects on the cardiovascular system, we believe that research into mechanical respiratory support deserves greater attention. In the future, studies of cardiogenic shock should collect data on other types of respiratory support, such as non-invasive ventilation and high-flow nasal cannulation, the period of ventilatory support, associated complications, the aetiology of respiratory failure, ventilator settings and modes, oxygen targets and the use of concurrent medications such as sedatives.