Heart Rate Variability in Acute and Chronic Pain: A Systematic Review of Autonomic Function and Pain Mechanisms

Aims: To investigate the relationship between heart rate variability (HRV) and acute and chronic pain, focusing on its potential as an objective tool for pain assessment.

Study Design: Integrative literature review.

Place and Duration of Study: The study was conducted through database searches (SCIELO, PUBMED, LILACS, BVS, and MEDLINE) between July 2024 and october 2024.

Methodology: The results indicate a significant reduction in HRV in patients with chronic pain, suggesting dysfunction in the parasympathetic nervous system. In acute pain contexts, HRV also decreases, reflecting an increase in sympathetic activity and a decrease in parasympathetic response. HRV differences were observed based on age and gender, with young adults showing greater autonomic reactivity compared to older adults, and men exhibiting a greater reduction in HRV in response to acute pain compared to women. These findings suggest that HRV could serve as an objective tool for assessing pain, especially in non-communicative patients.

Results: A significant reduction in HRV was observed in patients experiencing chronic pain, which indicates parasympathetic nervous system dysfunction. In acute pain scenarios, HRV typically decreases, reflecting increased sympathetic activity and reduced parasympathetic response. Differences in HRV changes were also noted based on age and gender, with young adults experiencing greater autonomic reactivity compared to older individuals, and men showing more substantial HRV reduction in response to acute pain compared to women.

Conclusion: HRV shows promise as an objective pain indicator, providing healthcare professionals with an additional tool for assessing pain intensity and intervention effectiveness. However, there is a need for standardization in HRV measurement techniques and further studies to explore its clinical applications across various populations and health conditions. Variability in pain induction methods and HRV measurement approaches in the analyzed studies also represents a limitation, highlighting the need for more uniform methodologies to consolidate HRV use in pain contexts.