Organizing Intensive Care for Patients Undergoing Cardiac Surgery*
One strategy to improve outcomes after cardiac surgery may be to target the organization and management of the ICU. Observational data show that intensivist physician staffing and interprofessional rounds are associated with lower risk-adjusted mortality compared with the ICUs staffed by nonintensivists (3, 4), and the Society of Critical Care Medicine advocates that all ICU patients, including cardiac surgery patients, receive care from a trained intensivists (5). It stands to reason that by extending the intensivist-led, interprofessional staffing model to cardiac surgery ICUs, lives could be saved. Yet, surprisingly, ICU organization in the cardiac surgery population is extremely understudied, with little direct evidence that ICU management might be a lever for improving outcomes.
Lane-Fall et al (6) attempt to fill this knowledge gap through a retrospective cohort study in this issue of Critical Care Medicine. The investigators surveyed nurse managers in 57 cardiac surgery ICUs in Pennsylvania about their organizational practices. For the 47 responding ICUs, they linked the survey to patient-level administrative claims data. In contrast to most prior work, they found no link between ICU organization and patient outcomes. Specifically, neither intensivist physician staffing, pharmacist participation on rounds, respiratory therapist participation on rounds nor having an ICU dedicated to cardiac surgery was statistically significantly associated with lower risk-adjusted mortality. There was also no relationship between mortality and nurse staffing factors such as the proportion of ICU nurses with a bachelor’s degree.
Although methodologically strong, the study does have several key limitations. The dataset lacked granular physiologic variables for risk adjustment, so it is possible that well-staffed ICUs admit patients who are sicker in unmeasured ways, leading to confounding by severity of illness. Additionally, the authors assessed ICU organization through a survey of ICU nurse managers, whose responses to organizational surveys are known to differ from physician ICU directors, calling the reliability of the survey into question (7). Furthermore, the study may be underpowered to detect a clinically important result—the CIs for the relative odds of mortality associated with intensivist staffing are wide and do not exclude a clinically significant effect.
Despite these limitations, this study (6) has several important implications. Most saliently, this study (6) adds to a growing body of literature demonstrating that, despite conventional wisdom, in the modern era, the link between intensivist staffing and patient outcome is not as strong as previously thought (8, 9). Taken together, these studies support a conceptual model of ICU organization in which intensivists are but one way among many to improve quality. Clearly, some cardiac surgery ICUs, particularly those with extremely high acuity and frequent use of extracorporeal membrane oxygenation, will always need intensivists to comanage the patients. However, community hospital ICUs that mostly admit patients after routine coronary artery bypass graft (CABG) may not need a dedicated intensivist so long as they adopt other systematic strategies to maintaining evidence-based practice and preparedness in case of a true critical emergency.
Some of these strategies are revealed by the work of Lane-Fall et al (6). For example, among study ICUs, 86% used advanced practice providers, 84% used protocols for liberation of mechanical ventilation, and 84% limited nurse-to-patient ratios to 1:1 for immediate postoperative CABG patients.