Atrial natriuretic factor in normothermic and hypothermic cardiopulmonary bypass

Prognostic value of biomarkers after cardiopulmonary bypass in pediatrics: The prospective PANCAP study

Objective

To assess the usefulness of procalcitonin, pro-adrenomedullin and pro-atrial natriuretic peptide as predictors of need for mechanical ventilation and postoperative complications (need for inotropic support and bacterial infection) in critically ill pediatric patients after cardiopulmonary bypass.

Design

A prospective, observational study

Setting

Pediatric intensive care unit.

Patients

Patients under 18 years old admitted after cardiopulmonary bypass.

Measuraments and main results

Serum levels of procalcitonin, pro-adrenomedullin and pro-atrial natriuretic peptide were determined immediately after bypass and at 24–36 hours. Their values were correlated with the need for mechanical ventilation, inotropic support and bacterial infection. One hundred eleven patients were recruited. Septal defects (30.6%) and cardiac valve disease (17.1%) were the most frequent pathologies. 40.7% required mechanical ventilation, 94.6% inotropic support and 15.3% presented invasive bacterial infections. Pro-adrenomedullin and pro-atrial natriuretic peptide showed significant high values in patients needing mechanical ventilation. Cut-off values higher than 1.22 nmol/L and 215.3 pmol/L, respectively for each biomarker, may indicate need for mechanical ventilation with an AUC of 0.721 and 0.746 at admission and 0.738 and 0.753 at 24–36 hours, respectively but without statistical differences. Pro-adrenomedullin and procalcitonin showed statistically significant high values in patients with bacterial infections.

Conclusions

After bypass, pro-adrenomedullin and pro-atrial natriuretic peptide are suitable biomarkers to predict the need for mechanical ventilation. Physicians should be alert if the values of these markers are high so as not to progress to early extubation. Procalcitonin is useful for predicting bacterial infection. This is a preliminary study and more clinical studies should be done to confirm the value of pro-adrenomedullin and pro-atrial natriuretic peptide as biomarkers after cardiopulmonary bypass.

The role of natriuretic peptide receptor-A signaling in unilateral lung ischemia-reperfusion injury in the intact mouse

Ischemia-reperfusion (IR) causes human lung injury in association with the release of atrial and brain natriuretic peptides (ANP and BNP), but the role of ANP/BNP in IR lung injury is unknown. ANP and BNP bind to natriuretic peptide receptor-A (NPR-A) generating cGMP and to NPR-C, a clearance receptor that can decrease intracellular cAMP. To determine the role of NPR-A signaling in IR lung injury, we administered the NPR-A blocker anantin in an in vivo SWR mouse preparation of unilateral lung IR. With uninterrupted ventilation, the left pulmonary artery was occluded for 30 min and then reperfused for 60 or 150 min. Anantin administration decreased IR-induced Evans blue dye extravasation and wet weight in the reperfused left lung, suggesting an injurious role for NPR-A signaling in lung IR. In isolated mouse lungs, exogenous ANP (2.5 nM) added to the perfusate significantly increased the filtration coefficient sevenfold only if lungs were subjected to IR. This effect of ANP was also blocked by anantin. Unilateral in vivo IR increased endogenous plasma ANP, lung cGMP concentration, and lung protein kinase G (PKG(I)) activation. Anantin enhanced plasma ANP concentrations and attenuated the increase in cGMP and PKG(I) activation but had no effect on lung cAMP. These data suggest that lung IR triggered ANP release and altered endothelial signaling so that NPR-A activation caused increased pulmonary endothelial permeability.

Elevated flow rate during cardiopulmonary bypass is associated with fluid accumulation

OBJECTIVE

High flow rates during cardiopulmonary bypass are assumed to increase fluid accumulation. This study aimed to determine whether two different flow rates during cardiopulmonary bypass alter the intraoperative fluid balance and extravasation rate.

METHODS

Sixteen pigs underwent 60 minutes of normothermic bypass, followed by 90 minutes of hypothermic bypass. A high-flow group (HF group, n = 8) had a cardiopulmonary bypass flow rate of 110 mL x kg(-1) x min(-1) and a low-flow group (LF group, n = 8) had a rate of 80 mL x kg(-1) x min(-1). Blood chemistry, hemodynamic parameters, plasma and interstitial colloid osmotic pressure, net fluid balance, plasma volume, fluid extravasation rate, and total tissue water content were measured or calculated. Results are presented as mean (standard deviation).

RESULTS

The average net fluid balance during cardiopulmonary bypass was 1.02 (0.25) and 0.73 (0.23) mL x kg(-1) x min(-1) in the HF group and LF group, respectively (P < .05). The average fluid extravasation rate was 0.98 (0.22) and 0.77 (0.22) mL x kg(-1) x min(-1) in the HF group and the LF group (P = .07). Total water content was higher in the kidneys (P < .05) and tended to be higher in the lungs (P = .05), liver (P = .07), and brain (P = .07) of the HF group than in those of the LF group. The between-group differences in net fluid balance and fluid extravasation rate were present during the first 30 minutes of normothermic cardiopulmonary bypass. Thereafter, the values stabilized and remained similar in the two groups. Plasma volume and systemic vascular resistance differed between the groups.

CONCLUSION

Cardiopulmonary bypass flow rate of 110 mL x kg(-1) x min(-1) was associated with higher positive net fluid balance and fluid extravasation rate than 80 mL x kg(-1) x min(-1). The effect was mainly observed in the initial phase of cardiopulmonary bypass.

Hemodynamic improvement is faster after percutaneous ASD closure than after surgery

OBJECTIVES

Hemodynamic effects of surgical and percutaneous closure of atrial septal defect (ASD) were evaluated.

BACKGROUND

ASD causes volume overload of right ventricle (RV) and is associated with distortion and dysfunction of left ventricle (LV). The amount and timing of hemodynamic changes after ASD closure are not well known.

METHODS

The study group consisted of 7 children treated surgically and 17 treated in the catheterization laboratory. In the control group, there were 51 healthy children. RV size and LV end-diastolic and systolic dimensions, volumes, and function were examined by two- and three- dimensional echocardiography and serum concentrations of natriuretic peptides measured prior to ASD closure, and 1, 6, and 12 months thereafter.

RESULTS

In all children with ASD, during the 1-year follow-up, the z score of RV end-diastolic diameter decreased from a median 5.00 SD to 2.25 SD (P < 0.001). Dilatation of RV did not resolve entirely during 1-year follow-up in either treatment group. End-diastolic LV diameter increased from -1.50 to -0.50 SD (P < 0.001). LV size increased slower in the surgical subgroup but reached control levels in both groups. Concentrations of natriuretic peptides increased during the first month after ASD closure and normalized thereafter in patients treated percutaneously but remained higher than in controls in patients treated surgically.

CONCLUSIONS

During 1-year follow-up after ASD closure, RV size decreases but does not normalize in all patients. The size of the LV normalizes after ASD closure but the increase in LV size is slower in patients treated surgically. Serum levels of ANPN and proBNP are elevated prior to ASD closure but decrease thereafter to control levels in patients treated with the percutaneous technique but not in those treated surgically.