The Out-of-Hospital Management of Acute Heart Failure

Abstract

Acute heart failure (AHF) is one of the common cardiac emergencies encountered in the out-of-hospital setting. Making the diagnosis and instituting treatment in the prehospital setting not only ameliorates symptoms but may prevent the disease’s progression to pulmonary edema. The pathogenesis of acute heart failure and subsequently acute pulmonary edema (APE) most commonly arises from systolic failure. This form of failure results from the redistribution of intravascular fluid to the lungs secondary to acutely elevated left ventricular filling pressures. Although systolic failure is most common, diastolic dysfunction is becoming more evident and equally in need of treatment. Understanding the pathologic process provides the basis for the defining type and need for immediate management of AHF. Treatment entails reduction of left ventricular (LV) preload and afterload, ventilatory support, which may also assist diastolic dysfunction, and, if needed, inotropic support. Where possible, an attempt should be made to identify and treat underlying factors that may be contributing to the elevated left ventricular filling pressures and/or dysfunctional right heart. The pharmacologic agent most available and effective for out-of-hospital management is sublingual nitroglycerin. Where possible, this should be combined with noninvasive positive pressure ventilation (NIPPV). Diuretics should be used with caution, if at all, as they carry higher risks, especially if the patient is misdiagnosed. Opioids should rarely if ever be used as they limited physiologic benefit and may increase mortality. If sedation is needed, low-dose benzodiazepine may be helpful. A role for angiotensin-converting enzyme (ACE) inhibitors has yet to be documented in the out-of-hospital setting but may be used by some air medical systems. Noninvasive positive pressure ventilation, especially continuous positive pressure ventilation (CPAP), is an effective adjunct to our current treatment. Technical improvements now make this a first-line therapy, or in equivocal cases, an option, to drug management. Noninvasive ventilation decreases the need for endotracheal intubation, which is more difficult and hazardous in the field setting and in this group of patients. Future technology may soon allow a noninvasive airway management system to provide either CPAP or bi-level positive airway pressure (BiPAP), emulating what is available in the hospital environment. Currently, there is limited technology, in the out-of-hospital setting, to assist in the diagnosis of AHF. Thus, providers must depend on their history and physical examination. The evolution of novel, rapid, bedside diagnostic testing may prove value in assisting EMS personnel in making the correct diagnosis.