Physical complications in survivors of acute lung injury: A 2-year longitudinal prospective study.

摘要

Survivors of critical illness experience significant decrements in physical function after hospital discharge. Using acute lung injury (ALI) as a model for critical illness, our overall goal is to evaluate the effect of existing intensive care exposures on ALI patients' long-term morbidity. ALI is a relatively common syndrome causing respiratory failure and requiring mechanical ventilation in an intensive care unit (ICU). ALI imposes a significant public health burden, with a total number of deaths similar to breast cancer or HIV infection. Existing studies of long-term patient outcomes after ALI have demonstrated important and persistent physical health morbidity in survivors. Specifically, many ALI survivors have significant ICU-acquired weakness (ICUAW) that may persist for up to 5 years after ICU discharge.;Although these studies have provided important and novel insights, they had limited sample size and duration of follow-up, and did not provide detailed information regarding the management of these patients. Using prospective data from the Improving Care of Acute Lung Injury Patients (ICAP) study, we determined epidemiology, risk factors, and impact of ICUAW in ALI survivors. Given the importance of the assessment for ICUAW using manual muscle strength testing (MMT), and controlling for important confounders, including baseline comorbidities which influence physical function (using the Functional Comorbidity Index [FCI]), we also evaluated the inter-rater reliability of these instruments.;Study 1: We evaluated inter-rater reliability for specially-trained evaluators ("trainees") undergoing quality assurance for the ICAP study, and a reference rater performing MMT using both simulated and actual patients recovering from critical illness. Across 26 muscle groups tested by 19 trainee-reference rater pairs, the median (interquartile range) percent agreement and intraclass correlation coefficient (ICC; 95% CI) were: 96% (91%, 98%) and 0.98 (0.95, 1.00), respectively. Across all 19 pairs, the ICC (95% CI) for the overall composite MMT score was 0.99 (0.98-1.00). When limited to actual patients, the ICC was 1.00 (95% CI 0.99-1.00). The agreement (kappa; 95% CI) in detecting clinically-significant weakness was 0.88 (0.44-1.00). Thus, MMT has excellent inter-rater reliability in trained examiners and is a reliable method of comprehensively assessing muscle strength.;Study 2: The Functional Comorbidity Index (FCI) was recently developed to predict physical function in ALI patients using comorbidity data. For reliability, we evaluated the intraclass correlation coefficient (ICC) for FCI among trained research staff performing data collection (using in-patient discharge summaries [primary objective]) for 421 acute lung injury patients enrolled in the ICAP study. For validity and accuracy, we compared the detection of FCI comorbidities across three types of inpatient medical records (using hospital discharge summaries and admission records versus complete chart review [secondary objectives]), and the association of the respective FCI scores obtained with patients' SF-36 physical function subscale (PFS) scores at 1-year follow-up. Inter-rater reliability was near-perfect (ICC 0.91; 95% CI 0.89-0.94). Hospital admission records and discharge summaries (vs. complete chart review) significantly underestimated the total FCI score. However, using multivariable linear regression, FCI scores collected using each of the three types of inpatient medical records had similar associations with PFS, suggesting similar predictive value. Data collection using inpatient discharge summaries represents a reliable and valid method for collecting FCI comorbidity information.;Study 3: Survivors of critical illness frequently develop substantial and persistent physical complications. We determine the epidemiology of muscle weakness, physical function, and health-related quality of life (HRQOL), and their associations with critical illness and ICU exposures in 222 survivors undergoing longitudinal follow-up at 3, 6, 12, and 24 months after ALI in the ICAP study. Patients underwent standardized clinical evaluations of extremity, hand grip, respiratory muscle strength; anthropometrics (height, weight, mid-arm circumference, triceps skin fold thickness); 6-minute walk distance, and the Medical Outcomes Short-Form 36 (SF-36) HRQOL survey. Over one-third of survivors had objective evidence of muscle weakness at hospital discharge, with most improving within 12 months. This weakness was associated with substantial impairments in physical function and HRQOL that persisted at 24 months. The duration of bed rest during critical illness was consistently associated with weakness throughout 24-month follow-up. The cumulative dose of systematic corticosteroids and use of neuromuscular blockers in the ICU were not associated with weakness. Muscle weakness is common after ALI, usually recovering within 12 months. This weakness is associated with substantial impairments in physical function and HRQOL that continue beyond 24 months. These results provide valuable prognostic information regarding physical recovery after ALI. Evidence-based methods to reduce the duration of bed rest during critical illness may be important for improving these long-term impairments.;These studies suggest that both MMT and FCI, as used in our study, are highly reliable among trained evaluators. Muscle weakness is common after ALI, usually recovering within 12 months. This weakness is associated with substantial impairments in physical function and HRQOL that continue beyond 24 months. These results provide valuable prognostic information regarding physical recovery after ALI. Evidence-based methods to reduce the duration of bed rest during critical illness may be important for improving these long-term impairments.