Utility of B-type natriuretic peptide and N-terminal pro B-type natriuretic peptide in evaluation of respiratory failure in critically ill patients.
OBJECTIVE
B-type natriuretic peptide (BNP) and N-terminal pro BNP (NTproBNP) have been shown to correlate with pulmonary arterial wedge pressure (PAWP) in patients with heart failure. We studied whether BNP and/or NTproBNP can differentiate high- vs low-PAWP respiratory failure in ICU patients. We also evaluated if BNP and NTproBNP will reflect accurately cardiac dysfunction and predict 30-day survival.


METHODS
Prospective observational study of ICU patients in an urban teaching hospital.


METHODS
Forty-one consecutive patients with hypoxic respiratory failure undergoing pulmonary artery catheterization were enrolled between January and December, 2003.


METHODS
BNP and NTproBNP were assayed from a venous blood sample. Hemodynamic variables were obtained at the time blood was drawn. Survival was documented at day 30.


RESULTS
BNP and NTproBNP correlated significantly with each other (r = 0.656, p < 0.001) and inversely with hemodynamic markers of contractility: BNP with cardiac index (CI) [r = - 0.481, p < 0.02], and left ventricular stroke work index (LVSWI) [r = - 0.384, p < 0.02]; NTproBNP with CI (r = - 0.441, p < 0.02) and LVSWI (r = - 0.623, p < 0.001). BNP and NTproBNP did not correlate with PAWP. We created receiver operating characteristic (ROC) curves for detection of contractile dysfunction using different LVSWI cutoffs. Area under the ROC (AUROC) values were larger and more consistent for NTproBNP than for BNP. For LVSWI < 35 g.m/m(2): BNP AUROC = 0.643, NTproBNP AUROC = 0.885 (p < 0.02); for LVSWI < 30 g.m/m(2): BNP AUROC = 0.754 (p < 0.02) and NTproBNP AUROC = 0.884 (p < 0.001). Mean (+/- SE) concentrations did not differ between the survivors and non-survivors: BNP, 909.3 +/- 264.2 pg/mL vs 840.9 +/- 171.2 pg/mL; NTproBNP, 11,630.6 +/- 3,181.8 pg/mL vs 11,777.6 +/- 2,989.9 pg/mL, respectively.


CONCLUSIONS
NTproBNP and BNP failed to differentiate high- vs low-PAWP respiratory failure but were inversely correlated with indexes of cardiac contractility. With higher accuracy, NTproBNP may be a more discerning marker than BNP in patients with milder cardiac dysfunction. Neither peptide predicted short-term mortality.
Jefic
Dane
D
Department of Medicine, Wayne State University School of Medicine, 22201 Moross Rd, PB II Ste 80, Detroit, MI 48236, USA. danejefic@yahoo.com
Lee
John W
JW
Jefic
Dijana
D
Savoy-Moore
Ruth T
RT
Rosman
Howard S
HS
D000368:Aged; D015415:Biomarkers / Q000097:blood; D016638:Critical Illness; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D009419:Nerve Tissue Proteins / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D012131:Respiratory Insufficiency / Q000097:blood* / Q000401:mortality; D016019:Survival Analysis
D015415:Biomarkers; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain