Class I
Patients with cardiac disease but without resulting limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnea, or anginal pain.
Class II
Patients with cardiac disease resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea, or anginal pain.
Class III
Patients with cardiac disease resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary activity causes fatigue, palpitation, dyspnea, or anginal pain.
Class IV
Patients with cardiac disease resulting in inability to carry on any physical activity without discomfort. Symptoms of heart failure or the anginal syndrome may be present even at rest. If any physical activity is undertaken, discomfort increases.
At the present time, we suggest the following: (see Table 9.2) [1] All patients who present with AHF should be asked if they feel short of breath, or have a sensation of breathlessness. Determining the impact of breathlessness on a patient’s daily living may also provide a reference point for severity. For example, a patient who normally walks three blocks without dyspnea can now walk only five steps. Another example would be the patient who has dyspnea with any movement but is not dyspneic at rest and whether this represents a change from the patient’s baseline functional status. In addition, whether the patient experiences orthopnea or paroxysmal nocturnal dyspnea should also be determined. If a change from baseline is noted, suspicion for worsening volume overload is increased [2]. After treatment, patients should be frequently reassessed to determine response to therapy. Caution is warranted for patients in whom the clinical exam and physician impression show marked improvement, yet patient-reported symptoms are unchanged. While undertreatment is one possibility, other causes of dyspnea (e.g., pulmonary embolism, emphysema) should be considered.
Table 9.2
Key points in the evaluation of the dyspneic patient with concern for AHF
Assess if patient’s dyspnea is different from their baseline functional respiratory status or if orthopnea or PND are present. |
CXR findings that indicate AHF may include pulmonary edema, Kerley B-lines, pulmonary vascular congestion, and pleural effusions. |
BNP < 100 pg/ml is highly sensitive to rule out AHF as cause of dyspnea. |
Lung ultrasound showing B-lines is highly sensitive and specific for AHF. |
Patients with hypoxia require supplemental oxygen via nasal cannula or facemask. |
If hypoxia or work of breathing is not improved with supplemental oxygen only, noninvasive positive pressure ventilation with CPAP or BPAP should be initiated. |
Endotracheal intubation should be performed in obtunded patients on arrival or patients who do not improve with CPAP/BPAP. |
There are additional clinical diagnostic tools that can aid in making the diagnosis of AHF that should be combined with the patient’s history and physical exam. Most, if not all, patients complaining of dyspnea in the emergency department will get a chest X-ray (CXR) performed. Pulmonary edema, Kerley B-lines, pulmonary vascular congestion, and pleural effusion(s) are various findings evident in a patient with AHF with fluid overload; while these CXR findings are quite specific with specificities greater than 90 %, they are poorly sensitive [15].
Natriuretic Peptides
Natriuretic peptides (NP), like BNP (brain natriuretic peptide) or NT-proBNP, are produced in the myocardium by myocytes secondary to increased ventricular filling pressure. Elevated NP levels are associated with AHF, although it can also be elevated in other diseases like pulmonary embolism and end-stage renal disease. The common cutoff used to exclude the presence of AHF is 100 pg/ml – at this cutoff level, BNP is highly sensitive with a negative likelihood ratio of less than 0.2 [15]. American College of Emergency Physician’s (ACEP) clinical policy guideline on the management of acute heart failure in the emergency department gives a level B recommendation for the use of BNP to improve diagnostic accuracy with the following guidelines: if BNP < 100 pg/dL, AHF is unlikely (negative likelihood ratio 0.1); if BNP > 500 pg/dL, AHF is likely (positive likelihood ratio 6) [16].
Lung Ultrasound
Lung ultrasound has emerged as a new modality to assist in the diagnosis of patients with dyspnea. Patients with AHF have pulmonary edema, or extravascular fluid in the lung interstitium and alveoli, which appears on lung ultrasound as B-lines. B-lines are reverberation artifacts that start at the pleural line, radiate down through the lung, and move with pleural sliding with respirations (see Fig. 9.1). A positive lung ultrasound of interstitial edema requires 3 or more B-lines in at least 2 intercostal spaces bilaterally. A recent meta-analysis by Al Deeb et al. evaluated the accuracy of lung ultrasound B-lines in the clinical diagnosis of acute cardiogenic pulmonary edema (ACPE) [18]. Seven studies were used in the final analysis, and the summed sensitivity and specificity of using lung ultrasound B-lines to diagnose ACPE are 94.1 % and 92.4 %, respectively. The positive likelihood ratio was 12.4 and the negative likelihood ratio was 0.06 [18]. Given these results, in patients with a moderate to high pretest probability of ACPE, the presence of B-lines significantly strengthens the diagnosis, whereas the lack of B-lines in a patient with low pretest probability of ACPE strongly supports an alternative cause of the patient’s dyspnea.
Airway Management
While most AHF patients do not require definitive airway control, those with severe respiratory distress require emergent and decisive management. Even those with only mild to moderate respiratory distress should be carefully assessed to determine the need for supplemental oxygen. This includes a thorough history, as clinical conditions permit, to assess for other causes or historical features contributing to dyspnea (e.g., fever and cough suggesting pneumonia, history of chronic obstructive pulmonary disease) as well as review of a complete set of vital signs, including oxygen saturation, and assessment of volume status in conjunction with a careful cardiovascular-pulmonary exam.
For patients who require supplemental oxygen, determining whether it is delivered via nasal cannula, varying oxygen-delivering masks or a ventilator after endotracheal intubation depends on the condition in which the patient presents as well as response to initial therapy. Moribund patients require definitive airway control with endotracheal intubation, whereas those whose clinical condition can be stabilized or rapidly reversed may be managed with alternative methods such as noninvasive ventilation (NIV) with bi-level positive airway pressure, BPAP, versus continuous positive airway pressure, CPAP. Unfortunately, no quick, simple, and universal method exists to determine which patients will turn around with NIV from those who require definitive airway control. At the present time, this continues to be a primarily clinical decision with experience demonstrating that patients who appear in the greatest distress often recover without intubation if initial therapy is begun rapidly (e.g., NIV in patients with flash pulmonary edema).
For those who require definitive airway management, rapid sequence intubation (RSI) is the preferred method. This involves the simultaneous administration of a sedative along with a paralytic without bag-valve mask ventilation. A key step in RSI is preoxygenation to minimize the risk of hypoxia after the patient is paralyzed. Patients who present with pulmonary edema will not be able to tolerate prolonged periods of apnea compared to healthy adults and will experience oxygen desaturation more rapidly [19]. The risk of aspiration versus hypoxia needs to be carefully considered for these patients as preoxygenation with BVM may be necessary. RSI has been the preferred mode of intubation in the emergency department for years and is both safe and effective [19].
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