Kussmaul’s sign is the paradoxical distention of the jugular veins during inspiration. Normally, jugular veins collapse with inspiration due to decreased intrathoracic pressure and enhanced venous return. Its presence reflects impaired right ventricular filling and is classically associated with constrictive pericarditis and mediastinal compression.

Pathophysiology

• Normal physiology:

  • Inspiration → decreased intrathoracic pressure → increased venous return → right atrial filling → jugular vein collapse.

• Abnormal physiology (Kussmaul’s sign):

  • Conditions such as constrictive pericarditis or external cardiac compression create a rigid barrier around the heart.

  • The right ventricle cannot accommodate the increased venous return during inspiration.

  • This results in jugular venous distention (JVD) rather than collapse.

• Additional associations:

  • Seen less commonly in right ventricular infarction, severe right heart failure, restrictive cardiomyopathy, or mediastinal tumors.

  • Rarely described in extreme circulatory disturbances such as toxin-induced coma or seizures.

Examination Technique

1. Positioning: Patient reclined at 30–45° with neck slightly turned.

2. Observation: Locate the highest jugular venous pulsation.

3. Respiration: Watch for changes during normal inspiration.

4. Documentation: Record the presence of inspiratory distention, laterality, and associated signs (e.g., edema, hepatomegaly).

5. Complementary findings: Pericardial knock, pulsus paradoxus, or Kussmaul’s breathing may support diagnosis.

Clinical Features

Differential Diagnosis

Special Populations

• Pediatrics:

  • Rare; may occur with congenital constrictive pericarditis or mediastinal masses.

  • Jugular veins small → subtle signs, requiring careful assessment.

• Geriatrics:

  • Often complicated by coexisting pulmonary or cardiac disease.

  • Presence of Kussmaul’s sign suggests advanced pathology and warrants urgent work-up.

Limitations

• Difficult to appreciate in obese patients or those with short, muscular necks.

• Must be differentiated from tricuspid regurgitation or normal venous pulsations.

• Requires quiet breathing and patient cooperation.

Patient Counseling

• Explain that jugular vein swelling during inspiration indicates the heart is struggling to fill properly, not a vein problem.

• Stress the need for further tests (echocardiography, CT, or MRI).

• Encourage reporting of new/worsening symptoms (dyspnea, swelling, fatigue).

• Reassure that the finding is a signpost, not a diagnosis by itself.

Conclusion

Kussmaul’s sign is a valuable clinical finding indicating restricted right ventricular filling. It is most commonly seen in constrictive pericarditis and mediastinal compression, but also occurs in other right heart pathologies. Recognizing the sign, along with complementary cardiovascular findings, facilitates timely referral, diagnosis, and management of potentially serious conditions.

References

1. Braunwald E. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2021.

2. McCance KL, Huether SE. Pathophysiology: The Biologic Basis for Disease in Adults and Children. 8th ed. Maryland Heights, MO: Elsevier; 2021.

3. Spodick DH. The Pericardium: A Comprehensive Textbook. 2nd ed. New York, NY: Marcel Dekker; 2003.

4. Lange RA, Hillis LD. Clinical recognition of Kussmaul’s sign and its significance in constrictive pericarditis. Circulation. 2002;105:223–227.