Chest CT Features are Associated With Poorer Quality of Life in Acute Lung Injury Survivors*

Abstract

Objectives Despite decreasing mortality rates in acute lung injury (ALI), studies of long term physical function in ALI survivors have consistently reported poorer quality of life persisting years into recovery for reasons that are not completely understood. We sought to determine if pulmonary dysfunction is independently associated with functional impairment among ALI survivors, and to determine if high resolution computed tomography could be used to predict its development. Design Secondary analysis of data from a randomized controlled trial in ALI. Setting Intensive care units at three academic medical centers. Patients Patients diagnosed with ALI who had high resolution computed tomography scans performed at 14 and/or 180 days after diagnosis. Interventions None. Measurements and main results An objective radiologic scoring system was used to quantify patterns present on chest high resolution computed tomography obtained at 14 and 180 days in patients with ALI. These scores were correlated in univariable and multivariable analyses with pulmonary function testing and quality of life survey data obtained at 180 days. Eighty-nine patients had evaluable data at day 14, and 47 at 180 days. At 180 days, increased radiologic scores for reticulation were associated with a decreased total lung capacity, forced vital capacity, and diffusing capacity for carbon monoxide (p values all <0.002). Decrements in quality of life attributable to pulmonary dysfunction were most strongly associated with higher radiologic scores. Additionally, radiologic scores at 14 days independently predicted poorer quality of life at 180 days, accounting for age, severity of illness, pneumonia as the ALI risk factor, and length of time on mechanical ventilation. Conclusions Among survivors of ALI, increasing chest high resolution computed tomography involvement correlated with restrictive physiology and poorer health related quality of life, implicating pulmonary dysfunction as a potential contributor to activity limitation in these patients.

Detection of Fibroproliferation by Chest High-Resolution CT Scan in Resolving ARDS

“…However, our recent investigations suggest that chest HRCT scans obtained at 14 days post ARDS diagnosis identifi es a subset of patients who will have persistent radiographic fi broproliferation much later, at 180 days, and also poorer pulmonary-specifi c quality of life. 6 Data from our present work complement these prior observations by demonstrating an association between poor respiratory compliance measured in the fi rst days aft er ARDS diagnosis with radiographic fi broproliferation at 14 days. Th ese data are clinically meaningful in suggesting that simple bedside ventilator measurements early in ARDS may help to identify and target patients who are most likely to have radiologic fi broproliferation during the resolution of their acute illness; that is, patients with the poorest respiratory compliance.…”

“…21,24,25 Our fi ndings suggest the potential of early HRCT scan evaluation in patients with ARDS with the poorest lung compliance to identify individuals who may be at risk for complications related to excessive fi broproliferation. 6 Emerging evidence suggests that HRCT scan scores measured very early (within days) aft er ARDS diagnosis using validated methods 7,8 may be helpful in prognosticating short-term outcomes, illustrated in a prospective observational study 9 in which evidence for chest HRCT scan fi broproliferation present on the fi rst day of ARDS diagnosis was associated with 60-day mortality. However, our recent investigations suggest that chest HRCT scans obtained at 14 days post ARDS diagnosis identifi es a subset of patients who will have persistent radiographic fi broproliferation much later, at 180 days, and also poorer pulmonary-specifi c quality of life.…”

“…[2][3][4][5] Moreover, recent data support a negative relationship between fi broproliferation and healthrelated quality of life in ARDS survivors. 6 Nevertheless, factors infl uencing the development of fi broproliferation are not well understood.…”

The fibroproliferative response in acute respiratory distress syndrome: mechanisms and clinical significance

“…1) that may persist for months to years after discharge from the ICU [9, 11, 16–18], although these changes were not observed in all studies [13]. Surprisingly, although the extent of reticular involvement in ARDS survivors has been associated with specific factors implicated in the pathogenesis of fibrotic lung disease, such as high airway pressures, hyperoxia and longer duration of mechanical ventilation [16, 17], few studies have systematically examined chest CT scans in association with physiological function among ARDS survivors [9, 11, 13, 18]. Published studies that have included both PFT and chest CT scans emphasise that persistent radiographical abnormalities are generally not severe in the majority of patients and have therefore been considered to be clinically unimportant [9, 11, 13].…”

Mechanisms of Lung Fibrosis Resolution

“…14 Studies assessing long-term outcomes in acute respiratory distress syndrome survivors report persistent lung dysfunction and computed tomographic abnormalities in only subsets of subjects, suggesting significant fibrosis resolution for most patients. 15,16 In summary, animal models of fibrosis in the kidney, liver, and lung indicate the potential to reverse a substantial fibrotic burden and return to near predisease function after the fibrogenic insult is extinguished. The concept of fibrosis reversal in solid organs is supported in human disease, where liver cirrhosis caused by hepatitis infection demonstrates marked resolution after antiviral treatment.…”