PURPOSE: To determine, in patients with acute lung injury (ALI) or the acute respiratory distress syndrome (ARDS), if clinical exam findings believed to indicate an ineffective circulation predict a low cardiac index (CI) or low mixed venous oxygen saturation (SvO2).
METHODS: The NIH/NHLBI ARDS Network Fluid and Catheter Treatment Trial (FACTT) enrolled 1000 patients in a factorial design comparing conservative and liberal fluid treatment strategies using parameters from a central venous catheter or a pulmonary artery catheter (PAC). We analyzed data on study days 1-7 from 478 patients randomized to a PAC. We used logistic regression to correlate low CI < 2.5 liters/min/m2 and low SvO2 < 60% with capillary refill time >2 sec, skin mottling, or cool skin, and with 24 hour fluid output and central venous pressure (CVP). We controlled for fluid treatment (liberal or conservative).
RESULTS: Prevalence of CI < 2.5 was 8% and SvO2 < 60% was 14%. High CVP (p=0.0012), low 24 hour fluid output (p=0.0135), and cool skin (p=0.0967) were associated with CI < 2.5 at p<0.1. High CVP (p=0.0002) and skin mottling (p=0.0186) were associated with SvO2 < 60% at p<0.1. The area under the ROC curve for the model predicting CI < 2.5 or SvO2 < 60% is 0.65. Skin mottling occurred in only 16 cases, but had a postive predictive value (PPV) of 0.5 for SvO2 < 60%, and the PPV increased as CVP increased. Skin mottling and a CVP > 14 mm Hg had a PPV of 0.78 for SvO2 < 60%.
CONCLUSION: Prevalence of CI < 2.5 is low and clinical exam findings of ineffective circulation are poor predictors of low CI. Skin mottling with a high CVP predicts an SvO2 < 60%.
CLINICAL IMPLICATIONS: Most patients with ALI/ARDS have a CI > 2.5 and an SvO2 > 60%. In patients with ALI/ARDS clinical exam findings of ineffective circulation have low predictive value for CI < 2.5, but skin mottling with a high CVP is predictive of low SvO2.
DISCLOSURE: Colin Grissom, None.