FIGURE 77.1 A diagnostic approach to tachycardia a Altered mental status, diaphoresis, hypertension b See Chapter 10 Shock HR, heart rate; EKG, electrocardiogram; SVT, supraventricular tachycardia; ARF, acute rheumatic fever Pericardial effusion may occur after blunt chest trauma, viral infection, or as a component of inflammatory diseases such as systemic lupus erythematosus Small effusions may be detected as a friction rub Large effusions often cause cardiogenic shock and may lead to muffling of heart sounds and EKG changes, such as low-voltage or T-wave flattening with “strain” pattern in leads V1 through V6, but are nonspecific Pericardial effusions are best identified using ultrasound Patients with evidence of significant circulatory impairment should