As such, VPW may prove to be a more accurate measure of intravascular volume DAPT secretase IC50 than either CVP or PAOP and may correlate better with actual intravascular volume than these intravascular pressure surrogates. Although our data lack a direct intravascular volume measurement, future studies could incorporate one as a different reference standard. It is noteworthy that even in this selected population of patients with noncardiogenic pulmonary edema, that VPW measurements moderately differentiated volume status.Our study also has other limitations. The patients enrolled in FACTT are a highly-selected group of patients with acute lung injury. This substudy evaluates data from a subset of the overall FACTT population. However, almost 30% of the enrolled patients were included, with five geographically diverse centers with heterogeneous patient populations participating.
Although all the data were collected prospectively during the conduct of the original study, this substudy represents a post-hoc, retrospective analysis. As such, many of the CXR and vascular pressure measurements did not occur simultaneously. To minimize any potential bias this might introduce, we limited our analysis to “matched” measurements and CXRs obtained within three hours of each other. Furthermore, although a VPW of 67 mm, was found to best predict a PAOP <8 mmHg the relatively few instances that conservative fluid management resulted in target PAOP or CVP measurements being reached resulted in wide confidence intervals for the sensitivity and specificity.
Similar to the cutoffs previously defined for differentiating patients with cardiogenic versus noncardiogenic edema [6,9], a VPW value of 72 or higher in our study, also discriminated a PAOP of at least 18 mmHg, which could represent cases where volume overload and hydrostatic edema may be contributing to the hypoxia and patients who may benefit from diuresis. Despite only having moderate sensitivity and specificity for predicting either volume overload or conservative fluid status, given its non-invasive nature, relative availability, and moderate sensitivity and sensitivity, we think these data support the use of VPW in a fluid management strategy when other measures, such as intravascular pressure measurements, are unavailable. A suggested algorithm is presented in Figure Figure55.Figure 5Suggested fluid management algorithm for ALI patients using VPW.
This study also has a number of strengths. We averaged the VPW measurements from multiple, independent, blinded readers of the CXRs, ranging from Dacomitinib a seasoned radiologist to intensivists with both extensive and limited prior experience in measuring VPW. Although inter-rater variability in this study was higher than that seen in previous studies [6,10], the VPW was still a significant predictor of intravascular status of the cohort.