Atrial natriuretic factor in the pediatric intensive care unit

ANF is a newly discovered peptide hormone that has significant implications for critical care physicians. This hormone, released from the heart, is especially responsive to fluid challenges as well as to many of the drugs commonly used in the ICU, including pressor and anesthetic agents. It has potent arterial vasodilating effects in pharmacologic doses and may be an important natural vasodilating agent, especially in the renal vascular bed. In patients on dopamine, it may potentiate the renal vasodilating effect and may provide an effective therapy for developing acute renal failure. Children with congenital heart disease and patients with CHF have elevated levels that clearly alter the aldosterone-angiotensin II system and may help us to understand and treat these conditions more effectively. Additionally, ANF may be a marker for adequacy of treatment in these disease states. The potential uses for ANF include diuresis in patients with fluid overload and diuretic resistance, treatment of CHF, and as a short-acting vasodilator. In the ICU, many therapies affect cardiac pressures and volume regulation. Positive-pressure ventilation may decrease the release of ANF by decreasing venous return and thus contribute to water retention. Drugs used in the ICU may directly affect ANF levels and markedly affect the homeostasis of fluid and electrolyte balance. This hormone system interacts intimately with renin, angiotensin II, and aldosterone. These interactions may play a significant role in the development of essential hypertension. Although not addressed in this article, the treatment and understanding of essential hypertension may be significantly advanced by understanding these relationships. It is clear that ANF acts as a hormone with complex interactions between the heart, volume status, electrolyte balance, renin-angiotensin II-aldosterone, vasopressin, and vascular tone. Although currently no definitive picture exists for these complex interactions, this is an exciting new hormone with significant implications for patient management in the ICU. As research continues, the picture will become clearer and our understanding of this new hormone more precise.