Fig. 11.1
Acute decompensated heart failure patient classification (Adapted from Nohria and Lewis [20], with permission)
Diuretic Therapy
Fluid removal through intravenous diuresis is an essential management strategy for AHF patients that present with congestion (2013 American College of Cardiology (ACC)/American Heart Association (AHA) Heart Failure Management Guidelines Class I, Level of Evidence (LOE) B). If unable to achieve effective diuresis with escalating doses of loop diuretics, a second diuretic agent (e.g. metolazone, chlorothiazide) may be added (ACC/AHA Class IIA, LOE B). Use of a continuous diuretic infusion has not been shown to be more effective than bolus therapy but may be considered for ease of dosing. Potential diuretic-related side effects that can negatively impact patient outcomes include electrolyte disturbances (hyponatremia, hypokalemia, and hypomagnesemia), metabolic alkalosis, ototoxicity, hyperuricemia, and hypotension. It is important to serially monitor clinical signs, daily weights, urine output, and electrolytes during treatment to determine the adequacy of decongestion and to avoid the untoward consequences of volume contraction (ACC/AHA Class I, LOE C). Under-treatment is common among hospitalized patients as seen in the Acute Decompensated Heart Failure National Registry (ADHERE), and failure to achieve adequate volume removal can be considered an important risk factor for hospital readmission [3].
Intravenous Vasodilators
Nitrates, such as nitroglycerin (10–350 mcg/minute) and sodium nitroprusside (5–300 mcg/minute) promote smooth muscle relaxation, resulting in decongestion and reduced cardiac filling pressures. Unpredictable patient responses to therapy and the risk for associated hypotension, however, mandate careful hemodynamic monitoring during treatment and the consideration of ICU admission for all individuals receiving parenteral nitrates. Nitroprusside has been shown to improve cardiac output, maintain adequate mean arterial pressures, and improve clinical outcomes in patients with acutely decompensated heart failure [4]. Nitroglycerin has a relatively short half-life and rapid onset of action. In AHF with significant pulmonary congestion, nitroglycerin can improve arterial oxygenation and hemodynamics through venous vasodilation. Duration of vasodilator therapy may be limited by hypotension, drug tachyphylaxis (nitroglycerin), and thiocyanate toxicity (nitroprusside).
Emergent Mechanical Circulatory Support
In situations of hemodynamic instability and reduced cardiac output that is refractory to pharmacologic intervention, mechanical circulatory support may be needed to reduce afterload and augment diastolic perfusion pressure (see Chap. 10, Management of Cardiogenic Shock).
Evidence Contour
Pulmonary Artery (PA) Catheters
PA catheterization allows direct measurement of cardiac filling pressures, pulmonary arterial pressures, cardiac output, and calculation of both systemic and pulmonary vascular resistance. Widespread adoption of this technology in all critically ill patients was tempered by findings which suggested an increased cost, mortality, and length of stay [5]. Specific to the heart failure population, the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial was conducted to assess the role of PA catheter-guided therapy in hospitalized individuals with AHF. Similar to other studies, there was no suggestion that PA catheters improved mortality; it did, however, result in increased adverse events such as infection, pulmonary infarction, and bleeding [6]. It has widely been assumed that the morbidity of PA catheterization is primarily related to operator experience [7]. Despite their unproven mortality benefit, PA catheters remain a viable diagnostic tool particularly in challenging cases of AHF. The 2013 ACC/AHA guidelines for heart failure management recommend PA catheter use in cases of refractory hypotension, difficult volume status determination, renal function deterioration despite therapy, and to guide inotrope therapy titration (Class IIA (LOE C)) [2].
Inotropic Agents
Management of AHF is often limited by low blood pressure and systemic hypoperfusion. Inotropic agents (e.g. dopamine, dobutamine, and milrinone) can augment contractility and chronotropy, resulting in increased stroke volume and cardiac output (Table 11.1). These goals are often accomplished with a tradeoff of increasing myocardial oxygen demand, increased heart rate, and increased risk for tachyarrhythmias. Improved hemodynamic response, however, has not always translated into improved patient survival. The Outcomes of a Prospective Trial of Intravenous Milrinone for Exacerbations of Chronic Heart Failure (OPTIME-CHF) investigators and data from the ADHERE registry showed that these agents may actually increase mortality when compared to standard diuretic or vasodilator therapies in AHF patients [8–10]. Therefore, inotropes are best used for short periods in the ICU in situations suggestive of emerging cardiogenic shock and end-organ failure. Inotropes can also be employed as a bridge to other definitive management strategies or used for palliative care purposes.
Table 11.1
Intravenous inotropic agents used in management of HF
Adrenergic agonists | Typical infusion dose (mcg/kg/min) | CO | HR | SVR | PVR | Possible adverse effects |
|---|---|---|---|---|---|---|
Dopamine | 5–10 | ↑ | ↑ | ↔ | ↔ | Headache, nausea, arrhythmia |
10–15 | ↑ | ↑ | ↑ | ↔ | ||
Dobutamine | 2.5–5 | ↑ | ↑ | ↓ | ↔ | Hyper- or hypotension, headache, arrhythmia, hypersensitivity |
5–20 | ↑ | ↑ | ↔ | ↔ | ||
PDE inhibitor | ||||||
Milrinone | 0.125–0.75 | ↑ | ↑ | ↓ | ↓ | Hypotension, arrhythmia |
Diuretic Dosing – Intermittent Versus Continuous
Patients presenting with AHF and congestion should receive intravenous loop diuretics as progressive bowel wall edema may limit oral diuretic absorption and efficacy. Less well understood is the differences between adopting a continuous infusion or interval dosing diuretic strategy. The Diuretic Optimization Strategies Evaluation (DOSE) trial compared intermittent IV diuresis to a continuous infusion strategy, and found them to have a similar effect on subjective symptoms and renal function [11]. A more recent meta-analysis evaluating ten randomized control trials similarly found no difference in resulting renal function, electrolyte disturbances, length of hospitalization, or cardiac or all-cause mortality between these two approaches [12].
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