title: Relationship between B-type natriuretic peptides and pulmonary capillary wedge pressure in the intensive care unit.
abstract: OBJECTIVE
  We examined whether B-type natriuretic peptides (BNP) can serve as noninvasive markers of pulmonary capillary wedge pressure (PCWP) in the setting of critical illness.
  
  
  BACKGROUND
  The BNP and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are highly correlated with left ventricular (LV) filling pressures in patients with depressed LV systolic function. However, their relationship to PCWP in a heterogeneous intensive care unit (ICU) population has not been established.
  
  
  METHODS
  We prospectively studied 40 patients in the ICU requiring invasive hemodynamic monitoring. Hemodynamics were recorded simultaneously with blood sampling for BNP and NT-proBNP.
  
  
  RESULTS
  The BNP (median 420 pg/ml) and NT-proBNP (median 3,304 pg/ml) levels were markedly elevated, but weakly correlated with PCWP (BNP, r = 0.40, NT-proBNP, r = 0.32) and other cardiac parameters. Peptide levels were approximately four-fold greater in patients with impaired (estimated glomerular filtration rate [eGFR] <60 ml/min) versus normal (eGFR >60 ml/min) renal function, despite similar PCWP, cardiac index, and LV ejection fraction. In addition, both BNP and NT-proBNP showed stronger correlations with PCWP in patients with preserved (BNP, r = 0.58, NT-proBNP, r = 0.73) versus impaired renal function (BNP, r = 0.48, NT-proBNP, r = 0.34). Interaction terms between eGFR and BNP (p = 0.06) and NT-proBNP (p = 0.04) suggest that eGFR modulates the relationship of these peptides to filling pressures.
  
  
  CONCLUSIONS
  The BNPs are markedly elevated, yet show only weak correlations to PCWP in ICU patients requiring invasive hemodynamic monitoring. Thus, a single value for BNP or NT-proBNP may not be a clinically useful noninvasive marker of filling pressures in the critically ill patient. This appears to be especially true in patients with impaired renal function.
authors.affiliation: Division of Cardiology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Forfia
authors.forename: Stanley P
authors.initials: SP
authors.lastname: Watkins
authors.forename: J Eduardo
authors.initials: JE
authors.lastname: Rame
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Stewart
authors.forename: Edward P
authors.initials: EP
authors.lastname: Shapiro
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002408:Catheters, Indwelling; D003422:Critical Care; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D009419:Nerve Tissue Proteins / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D011379:Prognosis; D011654:Pulmonary Edema / Q000097:blood / Q000628:therapy*; D011669:Pulmonary Wedge Pressure / Q000502:physiology*; D013223:Statistics as Topic; D018487:Ventricular Dysfunction, Left / Q000097:blood / Q000628:therapy*
chemical_list: D015415:Biomarkers; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain