Measurement and interpretation of central venous pressure: a narrative review

Summary

This narrative review explores the historical development, physiological underpinnings, measurement techniques, and clinical relevance of central venous pressure (CVP) in perioperative and critical care settings. Although traditionally used as a marker for fluid responsiveness and intravascular volume status, evidence now emphasizes that CVP alone is unreliable for guiding fluid therapy. Nonetheless, when used alongside waveform analysis and trend monitoring, CVP offers valuable insights into right heart function, venous congestion, and tissue perfusion.

Key Points:

1. Historical Context: CVP monitoring dates back over 70 years, evolving from early animal studies and initial human catheterizations, significantly influenced by Guyton’s foundational work on venous return and cardiac function interactions.
2. Physiological Basis: CVP represents the pressure within central thoracic veins, closely reflecting right atrial pressure. It is influenced by upstream blood volume, downstream cardiac pressures, and lateral thoracic pressures, especially under mechanical ventilation.
3. Measurement Techniques: Gold-standard CVP measurement involves central venous catheterization, usually via internal jugular or subclavian veins, carefully positioned and zeroed to atmospheric pressure, typically referenced to the tricuspid valve level.
4. Waveform Interpretation: The CVP waveform provides dynamic insights into cardiac mechanics through characteristic waves (a, c, v) and descents (x, y). Changes in waveform morphology indicate specific cardiac pathologies, such as right ventricular dysfunction or severe tricuspid regurgitation.
5. CVP and Fluid Responsiveness: Mounting evidence strongly indicates that isolated CVP measurements poorly predict fluid responsiveness due to complex interactions among venous return, cardiac function, and intrathoracic pressures.
6. Clinical Relevance of Elevated CVP: Persistently elevated CVP is associated with impaired organ perfusion and adverse outcomes, including acute kidney injury and higher mortality, particularly in cardiac surgical and critically ill populations.
7. Right Ventricular Dysfunction: Alterations in the CVP waveform, specifically diminished x-descent and exaggerated y-descent, signal right ventricular diastolic dysfunction, often linked with increased morbidity and mortality, particularly after cardiac surgery.
8. Non-invasive Monitoring Techniques: Emerging evidence supports using Doppler ultrasonography of large veins (hepatic, portal, and femoral veins) to complement CVP monitoring and diagnose right heart dysfunction non-invasively.
9. Impact on Organ Perfusion: Elevated CVP reduces mean arteriovenous pressure gradients, diminishing tissue perfusion, contributing to visceral organ dysfunction (e.g., cardio-intestinal syndrome, acute kidney injury), highlighting the importance of integrating CVP within comprehensive hemodynamic assessments.
10. Future Directions: The authors advocate a nuanced approach, integrating CVP trends, waveform analyses, and advanced monitoring modalities, moving beyond simplistic fluid responsiveness assessments, to enhance perioperative and critical care patient outcomes.

Conclusion

While absolute CVP values alone lack predictive value for fluid responsiveness, understanding CVP trends and waveforms, especially when combined with other monitoring modalities, remains critical in optimizing management of complex patients in perioperative and critical care contexts.