Fluid loading in rats increases serum brain natriuretic peptide concentration

Mechanism of Hyponatremia in Community-Acquired Pneumonia: Does B-type Natriuretic Peptide Play a Causative Role?

OBJECTIVE

Hyponatremia is a well-known sequela of community-acquired pneumonia (CAP). B-type natriuretic peptide (BNP) has a natriuretic effect and was found to be elevated in patients with CAP. We investigated whether BNP has a role in the pathophysiology of hyponatremia in pediatric CAP.

METHODS

Serum and urine electrolytes and osmolality, as well as NT-pro-BNP (N-BNP), were obtained in 49 hospitalized pediatric patients with CAP (29 with hyponatremia, 20 with normal sodium levels.

RESULTS

Urine sodium levels were lower in the hyponatremic group compared with the normonatremic group (24.3 meq/L vs 66.7 meq/L, P = 0.006). No difference in N-BNP levels was found between groups (median, 103.8 vs 100.1; P = 0.06; interquartile range, 63.7-263.3 pg/mL vs 47.4-146.4 pg/mL). N-BNP was not associated with serum or urinary sodium levels.

CONCLUSIONS

These results indicate that BNP is unlikely to play a causative role in the mechanism of hyponatremia in CAP.

Mid-regional pro-atrial natriuretic peptide and the assessment of volaemic status and differential diagnosis of profound hyponatraemia

BACKGROUND

Hyponatraemia is common and its differential diagnosis and consequent therapy management is challenging. The differential diagnosis is mainly based on the routine clinical assessment of volume status, which is often misleading. Mid-regional pro-atrial natriuretic peptide (MR-proANP) is associated with extracellular and cardiac fluid volume.

METHODS

A total of 227 consecutive patients admitted to the emergency department with profound hypo-osmolar hyponatraemia (Na < 125 mmol L(-1) ) were included in this prospective multicentre observational study conducted in two tertiary centres in Switzerland. A standardized diagnostic evaluation of the underlying cause of hyponatraemia was performed, and an expert panel carefully evaluated volaemic status using clinical criteria. MR-proANP levels were compared between patients with hyponatraemia of different aetiologies and for assessment of volume status.

RESULTS

MR-proANP levels were higher in patients with hypervolaemic hyponatraemia compared to patients with hypovolaemic or euvolaemic hyponatraemia (P = 0.0002). The area under the curve (AUC) to predict an excess of extracellular fluid volume, compared to euvolaemia, was 0.73 [95% confidence interval (CI) 0.62-0.84]. Additionally, in multivariate analysis, MR-proANP remained an independent predictor of excess extracellular fluid volume after adjustment for congestive heart failure (P = 0.012). MR-proANP predicted the syndrome of inappropriate antidiuresis (SIAD) versus hypovolaemic and hypervolaemic hyponatraemia with an AUC of 0.77 (95% CI 0.69-0.84).

CONCLUSION

MR-proANP is associated with extracellular fluid volume in patients with hyponatraemia and remains an independent predictor of hypervolaemia after adjustment for congestive heart failure. MR-proANP may be a marker for discrimination between the SIAD and hypovolaemic or hypervolaemic hyponatraemia.

A preliminary evaluation of plasma b-type natriuretic peptide as a screening test for left ventricular diastolic dysfunction in non-cardiac intensive care

Left ventricular filling and thus diastolic function are frequently monitored and managed in critical care. However, scant data exist regarding possible screening tests for diastolic dysfunction in the intensive care unit (ICU). The present study aimed to evaluate plasma b-type natriuretic peptide (BNP) as a marker of diastolic dysfunction in a single-centre cohort of 'non-cardiac' ICU patients. The ICU is non-cardiac in that it provides mixed medical/surgical services with the exception of cardiology, cardiac surgery and solid organ transplantation. Clinical data were recorded over the first 24 hours of ICU stay for 32 consecutive patients. Transthoracic echocardiogram and blood collection for BNP assay were then performed. Diastolic dysfunction was demonstrated in 34% (n=11). Mean ± standard deviation BNP values were higher with diastolic dysfunction (238 ± 195 vs 72 ± 78 pg/ml; P=0.003). A BNP threshold of >43 pg/ml yielded a sensitivity of 80% and a specificity of 59%; area under the receiver operating characteristic curve was 0.82. BNP correlated independently with E/e' (R=0.425; P=0.015) (E/e': peak early transmitral velocity [E]/early diastolic mitral annular velocity [e']) but not left ventricular ejection fraction (P=0.8), illness severity (Acute Physiological and Chronic Health Evaluation II; P=0.3) or fluid balance (P=0.4). Diastolic dysfunction was common in this cohort of non-cardiac ICU patients and was independently associated with a significantly higher BNP. The potential application as a screening test for diastolic dysfunction is likely to require a threshold lower than previously proposed for heart failure.

Cerebral salt wasting: pathophysiology, diagnosis, and treatment

Cerebral salt wasting (CSW) is a syndrome of hypovolemic hyponatremia caused by natriuresis and diuresis. The mechanisms underlying CSW have not been precisely delineated, although existing evidence strongly implicates abnormal elevations in circulating natriuretic peptides. The key in diagnosis of CSW lies in distinguishing it from the more common syndrome of inappropriate secretion of antidiuretic hormone. Volume status, but not serum and urine electrolytes and osmolality, is crucial for making this distinction. Volume and sodium repletion are the goals of treatment of patients with CSW, and this can be performed using some combination of isotonic saline, hypertonic saline, and mineralocorticoids.

Prediction of hospital outcome in septic shock: a prospective comparison of tissue Doppler and cardiac biomarkers

Introduction

Diastolic dysfunction as demonstrated by tissue Doppler imaging (TDI), particularly E/e' (peak early diastolic transmitral/peak early diastolic mitral annular velocity) is common in critical illness. In septic shock, the prognostic value of TDI is undefined. This study sought to evaluate and compare the prognostic significance of TDI and cardiac biomarkers (B-type natriuretic peptide (BNP); N-terminal proBNP (NTproBNP); troponin T (TnT)) in septic shock. The contribution of fluid management and diastolic dysfunction to elevation of BNP was also evaluated.

Methods

Twenty-one consecutive adult patients from a multidisciplinary intensive care unit underwent transthoracic echocardiography and blood collection within 72 hours of developing septic shock.

Results

Mean ± SD APACHE III score was 80.1 ± 23.8. Hospital mortality was 29%. E/e' was significantly higher in hospital non-survivors (15.32 ± 2.74, survivors 9.05 ± 2.75; P = 0.0002). Area under ROC curves were E/e' 0.94, TnT 0.86, BNP 0.78 and NTproBNP 0.67. An E/e' threshold of 14.5 offered 100% sensitivity and 83% specificity. Adjustment for APACHE III, cardiac disease, fluid balance and grade of diastolic function, demonstrated E/e' as an independent predictor of hospital mortality (P = 0.019). Multiple linear regression incorporating APACHE III, gender, cardiac disease, fluid balance, noradrenaline dose, C reactive protein, ejection fraction and diastolic dysfunction yielded APACHE III (P = 0.033), fluid balance (P = 0.001) and diastolic dysfunction (P = 0.009) as independent predictors of BNP concentration.

Conclusions

E/e' is an independent predictor of hospital survival in septic shock. It offers better discrimination between survivors and non-survivors than cardiac biomarkers. Fluid balance and diastolic dysfunction were independent predictors of BNP concentration in septic shock.

Controversies in the management of aneurysmal subarachnoid hemorrhage*

BACKGROUND

The care of patients with aneurysmal subarachnoid hemorrhage has evolved significantly with the advent of new diagnostic and therapeutic modalities. Although it is believed that these advances have contributed to improved outcomes, considerable uncertainty persists regarding key areas of management.

OBJECTIVE

To review selected controversies in the management of aneurysmal subarachnoid hemorrhage, with a special emphasis on endovascular vs. surgical techniques for securing aneurysms, the diagnosis and therapy of cerebral vasospasm, neuroprotection, antithrombotic and anticonvulsant agents, cerebral salt wasting, and myocardial dysfunction, and to suggest venues for further clinical investigation.

DATA SOURCE

Search of MEDLINE and Cochrane databases and manual review of article bibliographies.

DATA SYNTHESIS AND CONCLUSIONS

Many aspects of care in patients with aneurysmal subarachnoid hemorrhage remain highly controversial and warrant further resolution with hypothesis-driven clinical or translational research. It is anticipated that the rigorous evaluation and implementation of such data will provide a basis for improvements in short- and long-term outcomes.

Œdème pulmonaire neurogénique au cours des hémorragies sous-arachnoïdiennes et brain natriuretic peptide

We report two cases of neurogenic pulmonary oedema following subarachnoid haemorrhage. A 58-year-old woman became increasingly dyspneic and needed oxygen support during a few days. A 53-year-old woman rapidly developed clinical and laboratory signs of respiratory failure, recovering in 48 hours. In both cases, chest radiography showed bilateral diffuse infiltrates, electrocardiogram revealed ST abnormalities, and cardiac troponin I level was elevated. In both patients, pro brain natriuretic peptide level was increased whereas global cardiac function was normal. The factors initiating its secretion are discussed.