Interventions to increase the career capital of underrepresented groups

The cardiac hormones BNP and NT-proBNP have been found to be useful in many aspects in the management of heart failure.^27,57 With regards to diagnosis, studies have shown that they may be useful in differentiating acute dyspnea caused by congestive heart failure from other causes of dypsnea.⁵⁷ BNP levels can distinguish between cardiac and pulmonary causes of respiratory distress in neonates and children.⁶²

Measurements of cardiac hormone levels may be used to guide and optimize heart failure therapy; this is because their levels are increased according to the severity of cardiac impairment.⁶³ They may be useful clinically as a rule-out test as high levels calls for further investigation whereas normal levels have consistent and very high negative predictive values.⁶⁴ Most studies have addressed BNP rather than NT-proBNP, while others compared BNP and NT-proBNP assays. In a study by Richards et al⁶⁵ they found that BNP and NT-proBNP had nearly identical performance characteristics in detecting a left ventricular ejection fraction (LVEF) of less than 30% and in predicting hospital admission and cardiac mortality rates.

The PRIDE (ProBNP Investigation of Dyspnoea in the emergency department) study which measured NT-proBNP in 600 adult patients presenting to the emergency department with dyspnoea showed that NT-proBNP was both sensitive and specific

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for the diagnosis of congestive heart failure, in patients with acute heart failure who had median NTproBNP greater than 4000pg/ml compared with levels of 130pg/ml in patients without heart failure. They proposed a cutoff point of 300pg/ml to rule out heart failure.⁵⁹

Studies have shown serum BNP and NT-proBNP levels to be useful in the diagnosis of heart failure in the pediatric population as well. However most of the subjects investigated have been children with congenital heart disease and chronic renal failure undergoing hemodialysis.

Sahin et al⁶⁶ evaluated the diagnostic performance of serum BNP and NT-proBNP in children with congenital heart disease and cardiomyopathies. Their results showed that BNP and NT-proBNP levels were higher in both groups than in the control group and the increase in peptide levels was strongly correlated with the severity of heart failure. They concluded that NT-proBNP may be used in screening of risk groups for cardiac failure because of its higher sensitivity, but BNP may be specifically used in monitoring patients with heart failure. The age and nutritional status of the children involved in this study were not documented.

Elsharawy et al⁶⁷ also examined the diagnostic value of NT-proBNP in children with ventricular septal defect, and found a sensitivity and specificity of 90% and 80%

respectively. A study conducted by Anquita et al⁶⁸ found NT-proBNP to be an accurate means of diagnosing heart failure with a positive predictive value of 94%

and a negative predictive value of 68%.

Lowenthal et al⁶⁹ in a cross sectional study involving children aged 1 month to 7 years with single ventricle physiology examined the usefulness of BNP and NT- proBNP as biomarkers for heart failure. They found that there was a direct

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correlation between clinical heart failure and BNP levels in this group of children.

Ekure et al⁷⁰ examined the usefulness of NT-proBNP in children with heart failure secondary to congenital heart disease, and reported the sensitivity, specificity negative and positive predictive values of NT-proBNP to be 57% and 96%, 69% and 94% respectively. In addition, they demonstrated a high positive correlation between NT-proBNP and modified Ross scores.

Extensive electronic and manual literature search on various aspects of cardiac dysfunction in PEM did not yield any published original scientific article on the role of brain natriuretic peptide in children with primary protein-energy malnutrition.

However in a recently published paper, Radman et al⁷¹ studied the effect of preoperative nutritional status on postoperative outcomes in children undergoing surgery for congenital heart diseases, 71 children with congenital heart disease were enrolled in the prospective cohort study which involved assigning z scores as a measure of total body fat mass, and measuring plasma concentrations of prealbumin and albumin (markers of malnutrition) and B type natriuretic peptide ( a marker of myocardial stress) preoperatively. They found that lower total body fat mass and acute and chronic malnourishment were associated with worse clinical outcomes in children undergoing surgery for CHD and that there is an inverse correlation between total body fat mass and BNP levels. They also found that the duration of inotropic support and BNP levels increased concomitantly as measures of nutritional status decreased; supporting the hypothesis that malnourishment is associated with decreased myocardial function. They suggested based on their findings that BNP may be a marker of myocardial stress in malnourished children.

Patients with chronic renal failure most often are malnourished, and plasma BNP have been found to be associated with left ventricular dysfunction in these groups of

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patients. Chazot et al⁷² in a cross sectional study sought to determine the relationship between pre dialysis BNP and nutritional markers in chronic hemodialysis patients. Their study showed that several nutritional markers were negatively correlated with BNP levels, but not correlated with C-reactive protein (CRP) levels, interdialytic weight gain, or pre-dialysis mean arterial pressure (MAP). Hence the plasma BNP level was found to be associated with malnutrition but not with inflammation. However, this study was carried out in an adult population.

Whereas the two studies cited above suggest that increased natriuretic peptide levels may be associated with cardiac dysfunction in malnourished patients, studies that have looked at the relationship between obesity, heart failure and natriuretic peptide levels have shown that they are decreased in obese adults who have heart failure. ^73,74