Abbott i-STAT 1, System Manual

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BNP - 2
Art: 716969-00J Rev. Date: 23-May-12
Metrological Traceability
The i-STAT System test for B-type natriuretic peptide (BNP) measures BNP amount-of-substance
concentration in plasma or the plasma fraction of EDTA anticoagulated whole blood (units of measure: pg/
mL or ng/L) for in vitro diagnostic use. BNP values assigned to i-STAT’s controls and calibration verification
materials are traceable to i-STAT’s working calibrator prepared from synthetic BNP (Peptide International,
Louisville, KY, Cat# 4212v). i-STAT System controls and calibration verification materials are validated for
use only with the i-STAT System and assigned values may not be commutable with other methods. Further
information regarding metrological traceability is available from Abbott Point of Care Inc.
Reportable Range
The i-STAT BNP test will report 15 to 5000 pg/mL (ng/L). Samples below the reportable range will yield “<15
pg/mL” on the analyzer display screen. Samples above the reportable range will yield “>5000 pg/mL”.
Reference Range
Whole blood and plasma samples from 165 apparently healthy donors were assayed. The upper 95%
reference range was determined to be 50 pg/mL (ng/L).
Note: Each facility should establish its own reference range using the i-STAT BNP assay.
Clinical Significance
Congestive heart failure (CHF) is a complex clinical syndrome resulting in decreased cardiac output that is
insufficient to meet the body’s metabolic needs.
1
It may result from dysfunction of either ventricle in systole
(contraction), diastole (relaxation) or both. 2 The most common underlying cause of CHF is coronary artery
disease. Other causes include: hypertension, myocarditis, valvular heart disease and idiopathic (unknown).
3
Common symptoms include: paroxysmal nocturnal dyspnea (PND), orthopnea, dyspnea on exertion (DOE),
nocturnal cough and peripheral edema.
2
Clinical signs include elevated jugular venous pressure, rales on
lung auscultation, the presence of a third heart sound and peripheral edema.2 Unfortunately, these signs
and symptoms are variable, and when present, non-specific as other clinical entities such as chronic
obstructive pulmonary disease can produce a similar clinical picture.
4
B-type natriuretic peptide (BNP) is one of a family of structurally similar peptide neurohormones that also
includes atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) whose function is to regulate
blood pressure, electrolyte balances, and fluid volume. ANP is stored in granules within the atria and
released rapidly in response to atrial stretch. In contrast, BNP is synthesized, stored, and released primarily
by the ventricular myocardium in response to volume expansion and pressure overload.1 Pre-pro-BNP
(134 amino acids) is synthesized in the cardiac myocytes and is processed to a pro-BNP (108 amino acids)
precursor molecule. The pro-BNP is then subsequently cleaved into the physiologically active BNP (32
amino acids) and an N-terminal fragment referred to as N-Terminal pro-BNP (76 amino acids).
3
Numerous clinical trials suggest the potential clinical usefulness of plasma BNP in:
1. the diagnosis of dyspnea and CHF
4,5,
2. the detection of left ventricular systolic and diastolic dysfunction
6,7,
3. the prognosis of patients with CHF and acute coronary syndromes 8,9 , and
4. therapy monitoring for CHF patients
10,11.
Multiple studies establish the value of BNP for facilitating the diagnosis of CHF in patients presenting with
dyspnea.
12
Davis, et al, measured levels of ANP and BNP in 52 patients presenting with acute dyspnea.
12,13
They found that admission plasma BNP concentrations more accurately reflected the final diagnosis than
did ejection fraction (EF) levels or ANP plasma concentrations. Morrison, et al also showed that rapid