Dear Editor,
We read the article titled “High levels of B-type natriuretic peptide (BNP) predict weaning
failure from mechanical ventilation in adult patients after cardiac surgery” by Thiago Martins Lara
et al. with interest (11. Lara TM, Hajjar LA, Almeida JP, Fukushima JT, Barbas CS, Rodrigues AR, et al.
High levels of B-type natriuretic peptide predict weaning failure from mechanical ventilation in
adult patients after cardiac surgery. Clinics. 2013;68(1):33-8,
http://dx.doi.org/10.6061/clinics/2013(01)OA05.
http://dx.doi.org/10.6061/clinics/2013(0...
). The authors aimed to evaluate
whether serum levels of B-type natriuretic peptide are a predictor of weaning failure from
mechanical ventilation after cardiac surgery. They concluded that high BNP levels are predictive of
failure to wean from mechanical ventilation after cardiac surgery.
Plasma levels of BNP are increased in disorders associated with intravascular volume overload,
increased central venous pressure and left ventricular dysfunction. BNP secretion is directly
proportional to left ventricular wall stress and blood volume. Because of these associations, there
has been much interest in using BNP as a biomarker for heart failure (22. Schachner T, Wiedemann D, Fetz H, Laufer G, Kocher A, Bonaros N. Influence of
preoperative serum N-terminal pro-brain type natriuretic peptide on the postoperative outcome and
survival rates of coronary artery bypass patients. Clinics. 2010;65(12):1239-45,
http://dx.doi.org/10.1590/S1807-59322010001200004.
http://dx.doi.org/10.1590/S1807-59322010...
). However, high levels of BNP are present in many cases for reasons unrelated to
cardiac diseases.
In several studies, BNP levels were higher in women than in men, independent of age. Although the
reason for this difference is unknown, it is believed that estrogen may play a role. Furthermore,
levels of BNP increase with age, and this difference is not associated with “age-related” diastolic
dysfunction in either sex (33. Wang TJ, Larson MG, Levy D, Benjamin EJ, Leip EP, Wilson PW, et al. Natriuretic
Peptides. J Am Coll Cardiol. 2007;50(25):2357-68.). Obese individuals have low
circulating natriuretic peptide levels, and diabetes mellitus is also associated with low plasma
levels of natriuretic peptide (44. Wang TJ, Larson MG, Levy D, Benjamin EJ, Leip EP, Wilson PW, et al. Impact of
obesity on plasma natriuretic peptide levels. Circulation. 2004;109(5):594-600,
http://dx.doi.org/10.1161/01.CIR.0000112582.16683.EA.
http://dx.doi.org/10.1161/01.CIR.0000112...
).
In addition, elevated BNP levels may be observed in many diseases associated with hypervolemia,
such as chronic renal failure, chronic liver disease and hyperaldosteronism (55. Vasan RS, Benjamin EJ, Larson MG, Leip EP, Wang TJ, Wilson PW, et al. Plasma
natriuretic peptides for community screening for left ventricular hypertrophy and systolic
dysfunction: the Framingham heart study. JAMA. 2002;288(10):1252-9,
http://dx.doi.org/10.1001/jama.288.10.1252.
http://dx.doi.org/10.1001/jama.288.10.12...
). Furthermore, respiratory conditions, such as pulmonary embolism and chronic
obstructive pulmonary disease, are associated with high levels of BNP in the absence of left heart
failure.
One of the most important conditions associated with elevated BNP levels is sepsis. Many studies have shown significantly higher BNP levels in patients with sepsis, and this effect was not related to myocardial dysfunction (66. Bar SL, Swiggum E, Straatman L, Ignaszewski A. Nonheart failure-associated elevation of amino terminal pro-brain natriuretic peptide in the setting of sepsis. Can J Cardiol. 2006;22(3):263-6.).
In conclusion, high levels of BNP are presented as a predictive factor for failure to wean from mechanical ventilation after cardiac surgery in the study by Thiago Martins Lara et al. However, because BNP levels may be affected by many factors, the significance of those risk factors in weaning from mechanical ventilation after cardiac surgery should be considered in future large-scale prospective randomized clinical trials.
REFERENCES
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1Lara TM, Hajjar LA, Almeida JP, Fukushima JT, Barbas CS, Rodrigues AR, et al. High levels of B-type natriuretic peptide predict weaning failure from mechanical ventilation in adult patients after cardiac surgery. Clinics. 2013;68(1):33-8, http://dx.doi.org/10.6061/clinics/2013(01)OA05.
» http://dx.doi.org/10.6061/clinics/2013(01)OA05 -
2Schachner T, Wiedemann D, Fetz H, Laufer G, Kocher A, Bonaros N. Influence of preoperative serum N-terminal pro-brain type natriuretic peptide on the postoperative outcome and survival rates of coronary artery bypass patients. Clinics. 2010;65(12):1239-45, http://dx.doi.org/10.1590/S1807-59322010001200004.
» http://dx.doi.org/10.1590/S1807-59322010001200004 -
3Wang TJ, Larson MG, Levy D, Benjamin EJ, Leip EP, Wilson PW, et al. Natriuretic Peptides. J Am Coll Cardiol. 2007;50(25):2357-68.
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4Wang TJ, Larson MG, Levy D, Benjamin EJ, Leip EP, Wilson PW, et al. Impact of obesity on plasma natriuretic peptide levels. Circulation. 2004;109(5):594-600, http://dx.doi.org/10.1161/01.CIR.0000112582.16683.EA.
» http://dx.doi.org/10.1161/01.CIR.0000112582.16683.EA -
5Vasan RS, Benjamin EJ, Larson MG, Leip EP, Wang TJ, Wilson PW, et al. Plasma natriuretic peptides for community screening for left ventricular hypertrophy and systolic dysfunction: the Framingham heart study. JAMA. 2002;288(10):1252-9, http://dx.doi.org/10.1001/jama.288.10.1252.
» http://dx.doi.org/10.1001/jama.288.10.1252 -
6Bar SL, Swiggum E, Straatman L, Ignaszewski A. Nonheart failure-associated elevation of amino terminal pro-brain natriuretic peptide in the setting of sepsis. Can J Cardiol. 2006;22(3):263-6.
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No potential conflict of interest was reported.
Publication Dates
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Publication in this collection
May 2013