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Pulmonary vascular permeability index should not be called extravascular lung water pulmonary blood volume ratio
Critical Care volume 16, Article number: 417 (2012)
In their recent paper, Michelle Chew and colleagues  evaluated the performance accuracy of three extravascular lung water (EVLW) ratios in patients with shock at risk for or with acute lung injury (ALI). They indexed EVLW to actual body weight (ABW), predicted body weight (PBW) and pulmonary blood volume (PBV), and confirmed that all EVLW ratios were higher in patients with ALI and in non-survivors and correlated with respiratory parameters.
Although these findings are interesting, they deserve some comments. First, whereas indexing EVLW to PBW may reduce the number of patients with acute respiratory distress syndrome (ARDS) with normal EVLW, in this population, the EVLW/ABW index performed best . Furthermore, the absence of a link between EVLW and PaO2/FiO2 (calculated r2 of 0.14 to 0.23) could explain that these indices identified only 33% of ALI and 38% of ARDS cases. Second, the EVLW/PBV terminology appears very unusual. The transpulmonary thermodilution technique determines cardiac output, intrathoracic thermal volume (ITTV), pulmonary thermal volume (PTV) and global end-diastolic volume (Global end-diastolic volume (GEDV) = ITTV - PTV). The estimated blood volume of the chest (Intrathoracic blood volume (ITBV) = GEDV + PBV) permits the calculation of PBV (ITBV = 1.25 × GEDV - 28.4 ml) . Importantly, the PiCCO monitor automatically provides, at each calibration, an estimation of the pulmonary vascular permeability index (PVPI), based on the ratio of EVLW to PBV, which reflects alveolar-capillary barrier permeability and is of importance for the mechanisms of pulmonary edema [4, 5].
Thus, I believe that it would be more pertinent to use the PVPI instead of the EVLW/PBV ratio and that it is time to promote an international consensus on this.
actual body weight
acute lung injury
acute respiratory distress syndrome
extravascular lung water
global end-diastolic volume
intrathoracic blood volume
intrathoracic thermal volume
pulmonary blood volume
predicted body weight
pulmonary vascular permeability index.
Chew MS, Ihrman L, During J, Bergenzaum L, Ersson A, Unden J, Ryden J, Akerman E, Larsson M: Extravascular lung water index improves the diagnostic accuracy of lung injury in patients with shock. Crit Care 2012, 16: R1. 10.1186/cc10599
Michard F, Phillips C: Measuring extravascular lung water (and derived parameters) in patients with acute respiratory distress syndrome: what's right, what's wrong, and what's ahead? Crit Care Med 2009, 37: 2118-2119.
Sakka SG, Rühl CC, Pfeiffer UJ, Beale R, McLuckie A, Reinhart K, Meier-Hellmann A: Assessment of cardiac preload and extravascular lung water by single transpulmonary thermodilution. Intensive Care Med 2000, 26: 180-187. 10.1007/s001340050043
Monnet X, Anguel N, Osman D, Hamzaoui O, Richard C, Teboul JL: Assessing pulmonary permeability by transpulmonary thermodilution allows differentiation of hydrostatic edema from ALI/ARDS. Intensive Care Med 2007, 33: 448-453. 10.1007/s00134-006-0498-6
van der Heijden M, Groeneveld ABJ: Extravascular lung water to blood volume ratios as measures of pulmonary capillary permeability in nonseptic critically ill patients. J Crit Care 2010, 25: 16-22. 10.1016/j.jcrc.2009.02.009
The authors declare that they have no competing interests.
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Brivet, F.G. Pulmonary vascular permeability index should not be called extravascular lung water pulmonary blood volume ratio. Crit Care 16, 417 (2012). https://doi.org/10.1186/cc11208
- Acute Lung Injury
- Acute Respiratory Distress Syndrome
- Extravascular Lung Water
- Transpulmonary Thermodilution
- Predict Body Weight