Which maneuver best elicits the sound of a friction rub when leaning forward and holding breath?

Optimal Maneuver for Detecting Pericardial Friction Rub

The pericardial friction rub is best heard with the patient sitting upright and leaning forward while briefly holding their breath in end-expiration. 1

Why This Position Works

This specific positioning optimizes detection of the friction rub through two key mechanisms:

• Brings the heart closer to the chest wall, maximizing contact between the inflamed pericardial surfaces and the anterior chest wall where auscultation occurs 1
• Minimizes competing lung sounds during the brief breath hold, allowing the subtle friction rub to be more easily distinguished from respiratory sounds 1

The friction rub is typically most prominent at the left lower sternal border, though it may be audible across multiple precordial areas 1

Clinical Characteristics to Listen For

The pericardial friction rub has distinctive acoustic features that help differentiate it from other cardiac sounds:

• Triphasic character in most cases (though can be mono- or biphasic), corresponding to atrial systole, ventricular systole, and ventricular diastole 1
• Sounds like creaking leather or walking on fresh snow - described as coarse, grating, and creaking in quality 2
• Heard during both inspiration and expiration (biphasic respiratory pattern) 2
• Not cleared or affected by coughing, unlike pulmonary sounds 2

Critical Pitfalls to Avoid

The absence of a friction rub does NOT exclude pericarditis - this is perhaps the most important clinical caveat. The friction rub is:

• Only audible in approximately 18% to 84% of patients with confirmed acute pericarditis (most studies report around one-third of cases) 3, 1
• Highly transient and can disappear and reappear during the course of illness 1
• Highly specific when present but has poor sensitivity 3, 1

Practical Examination Approach

To maximize your chances of detecting a friction rub:

1. Position the patient sitting upright, leaning forward
2. Have them hold their breath briefly in end-expiration 1
3. Listen at the left lower sternal border with the diaphragm of your stethoscope 1
4. Perform multiple examinations over time, as the rub can be intermittent and may only be present transiently 1
5. Consider supine positioning if initially negative, as some friction rubs may be more pronounced when supine 1

Diagnostic Context

The friction rub is one of four key diagnostic criteria for acute pericarditis, with at least two criteria required for diagnosis 1, 3:

• Characteristic pleuritic chest pain (sharp, worse with inspiration, relieved by leaning forward)
• Pericardial friction rub on auscultation
• ECG changes (diffuse concave ST elevations, PR depressions)
• New or worsening pericardial effusion on echocardiography

A common misconception: The presence of a friction rub does NOT signify absence of pericardial effusion - friction rubs can occur with any amount of effusion, including large effusions 4