Difference in pulmonary permeability between indirect and direct acute respiratory distress syndrome assessed by the transpulmonary thermodilution technique: a prospective, observational, multi-institutional study.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is characterized by the increased pulmonary permeability secondary to diffuse alveolar inflammation and injuries of several origins. Especially, the distinction between a direct (pulmonary injury) and an indirect (extrapulmonary injury) lung injury etiology is gaining more attention as a means of better comprehending the pathophysiology of ARDS. However, there are few reports regarding the quantitative methods distinguishing the degree of pulmonary permeability between ARDS patients due to pulmonary injury and extrapulmonary injury. METHODS: A prospective, observational, multi-institutional study was performed in 23 intensive care units of academic tertiary referral hospitals throughout Japan. During a 2-year period, all consecutive ARDS-diagnosed adult patients requiring mechanical ventilation were collected in which three experts retrospectively determined the pathophysiological mechanisms leading to ARDS. Patients were classified into two groups: patients with ARDS triggered by extrapulmonary injury (ARDSexp) and those caused by pulmonary injury (ARDSp). The degree of pulmonary permeability using the transpulmonary thermodilution technique was obtained during the first three intensive care unit (ICU) days. RESULTS: In total, 173 patients were assessed including 56 ARDSexp patients and 117 ARDSp patients. Although the Sequential Organ Failure Assessment (SOFA) score was significantly higher in the ARDSexp group than in the ARDSp group, measurements of the pulmonary vascular permeability index (PVPI) were significantly elevated in the ARDSp group on all days: at day 0 (2.9 ± 1.3 of ARDSexp vs. 3.3 ± 1.3 of ARDSp, p = .008), at day 1 (2.8 ± 1.5 of ARDSexp vs. 3.2 ± 1.2 of ARDSp, p = .01), at day 2 (2.4 ± 1.0 of ARDSexp vs. 2.9 ± 1.3 of ARDSp, p = .01). There were no significant differences in mortality at 28 days, mechanical ventilation days, and hospital length of stay between the two groups. CONCLUSIONS: The results of this study suggest the existence of several differences in the increased degree of pulmonary permeability between patients with ARDSexp and ARDSp. TRIAL REGISTRATION: This report is a sub-group analysis of the study registered with UMIN-CTR (IDUMIN000003627).

Relationship between extravascular lung water and severity categories of acute respiratory distress syndrome by the Berlin definition.

INTRODUCTION: The Berlin definition divides acute respiratory distress syndrome (ARDS) into three severity categories. The relationship between these categories and pulmonary microvascular permeability as well as extravascular lung water content, which is the hallmark of lung pathophysiology, remains to be elucidated. The aim of this study was to evaluate the relationship between extravascular lung water, pulmonary vascular permeability, and the severity categories as defined by the Berlin definition, and to confirm the associated predictive validity for severity. METHODS: The extravascular lung water index (EVLWi) and pulmonary vascular permeability index (PVPI) were measured using a transpulmonary thermodilution method for three consecutive days in 195 patients with an EVLWi of ≥10 mL/kg and who fulfilled the Berlin definition of ARDS. Collectively, these patients were seen at 23 ICUs. Using the Berlin definition, patients were classified into three categories: mild, moderate, and severe. RESULTS: Compared to patients with mild ARDS, patients with moderate and severe ARDS had higher acute physiology and chronic health evaluation II and sequential organ failure assessment scores on the day of enrollment. Patients with severe ARDS had higher EVLWi (mild, 16.1; moderate, 17.2; severe, 19.1; P <0.05) and PVPI (2.7; 3.0; 3.2; P <0.05). When categories were defined by the minimum PaO2/FIO2 ratio observed during the study period, the 28-day mortality rate increased with severity categories: moderate, odds ratio: 3.125 relative to mild; and severe, odds ratio: 4.167 relative to mild. On independent evaluation of 495 measurements from 195 patients over three days, negative and moderate correlations were observed between EVLWi and the PaO2/FIO2 ratio (r = -0.355, P<0.001) as well as between PVPI and the PaO2/FIO2 ratio (r = -0.345, P <0.001). ARDS severity was associated with an increase in EVLWi with the categories (mild, 14.7; moderate, 16.2; severe, 20.0; P <0.001) in all data sets. The value of PVPI followed the same pattern (2.6; 2.7; 3.5; P <0.001). CONCLUSIONS: Severity categories of ARDS described by the Berlin definition have good predictive validity and may be associated with increased extravascular lung water and pulmonary vascular permeability. TRIAL REGISTRATION: UMIN-CTR ID UMIN000003627.

Limitations of global end-diastolic volume index as a parameter of cardiac preload in the early phase of severe sepsis: a subgroup analysis of a multicenter, prospective observational study.

BACKGROUND: In patients with severe sepsis, depression of cardiac performance is common and is often associated with left ventricular (LV) dilatation to maintain stroke volume. Although it is essential to optimize cardiac preload to maintain tissue perfusion in patients with severe sepsis, the optimal preload remains unknown. This study aimed to evaluate the reliability of global end-diastolic volume index (GEDI) as a parameter of cardiac preload in the early phase of severe sepsis. METHODS: Ninety-three mechanically ventilated patients with acute lung injury/acute respiratory distress syndrome secondary to sepsis were enrolled for subgroup analysis in a multicenter, prospective, observational study. Patients were divided into two groups-with sepsis-induced myocardial dysfunction (SIMD) and without SIMD (non-SIMD)-according to a threshold LV ejection fraction (LVEF) of 50% on the day of enrollment. Both groups were further subdivided according to a threshold stroke volume variation (SVV) of 13% as a parameter of fluid responsiveness. RESULTS: On the day of enrollment, there was a positive correlation (r = 0.421, p = 0.045) between GEDI and SVV in the SIMD group, whereas this paradoxical correlation was not found in the non-SIMD group and both groups on day 2. To evaluate the relationship between attainment of cardiac preload optimization and GEDI value, GEDI with SVV ≤13% and SVV >13% was compared in both the SIMD and non-SIMD groups. SVV ≤13% implies the attainment of cardiac preload optimization. Among patients with SIMD, GEDI was higher in patients with SVV >13% than in patients with SVV ≤13% on the day of enrollment (872 [785-996] mL/m(2) vs. 640 [597-696] mL/m(2); p < 0.001); this finding differed from the generally recognized relationship between GEDI and SVV. However, GEDI was not significantly different between patients with SVV ≤13% and SVV >13% in the non-SIMD group on the day of enrollment and both groups on day 2. CONCLUSIONS: In the early phase of severe sepsis in mechanically ventilated patients, there was no constant relationship between GEDI and fluid reserve responsiveness, irrespective of the presence of SIMD. GEDI should be used as a cardiac preload parameter with awareness of its limitations.