Aerobic exercise capacity in long-term survivors of critical illness: secondary analysis of the post-EPaNIC follow-up study

Abstract

Purpose: To evaluate aerobic exercise capacity in 5-year intensive care unit (ICU) survivors and to assess the association between severity of organ failure in ICU and exercise capacity up to 5-year follow-up. Methods: Secondary analysis of the EPaNIC follow-up cohort (NCT00512122) including 433 patients screened with cardiopulmonary exercise testing (CPET) between 1 and 5 years following ICU admission. Exercise capacity in 5-year ICU survivors (N = 361) was referenced to a historic sedentary population and further compared to demographically matched controls (N = 49). In 5-year ICU survivors performing a maximal CPET (respiratory exchange ratio > 1.05, N = 313), abnormal exercise capacity was defined as peak oxygen consumption (VO2peak) < 85% of predicted peak oxygen consumption (%predVO2peak), based on the historic sedentary population. Exercise liming factors were identified. To study the association between severity of organ failure, quantified as the maximal Sequential Organ Failure Assessment score during ICU-stay (SOFA-max), and exercise capacity as assessed with VO2peak, a linear mixed model was built, adjusting for predefined confounders and including all follow-up CPET studies. Results: Exercise capacity was abnormal in 118/313 (37.7%) 5-year survivors versus 1/48 (2.1%) controls with a maximal CPET, p < 0.001. Aerobic exercise capacity was lower in 5-year survivors than in controls (VO2peak: 24.0 ± 9.7 ml/min/kg versus 31.7 ± 8.4 ml/min/kg, p < 0.001; %predVO2peak: 94% ± 31% versus 123% ± 25%, p < 0.001). Muscular limitation frequently contributed to impaired exercise capacity at 5-year [71/118 (60.2%)]. SOFA-max independently associated with VO2peak throughout follow-up. Conclusions: Critical illness survivors often display abnormal aerobic exercise capacity, frequently involving muscular limitation. Severity of organ failure throughout the ICU stay independently associates with these impairments.