• Jan J Meeuse, Marco S P Löwik, Sabine A M Löwik, Eline Aarden, Arie M van Roon, Reinold O B Gans, Marten van Wijhe, Joop D Lefrandt, and Anna K L Reyners.
• Department of Internal Medicine, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands.
• Pain Med. 2013 Aug 1;14(8):1192-201.

ObjectiveWhen patients cannot indicate pain, physiological parameters may be useful. We tested whether heart rate variability (HRV) parameters, as reflection of sympathetic and vagal tone, can be used to quantify pain intensity.DesignProspective study.Subjects And SettingA standardized heat stimulus was applied to the forearm in 75 healthy volunteers during three study periods of 2 minutes.MethodsBefore and after each application, pain intensity was measured by a visual analog scale (VAS) and inter beat interval (IBI) was recorded. Standard deviation of normal to normal beat intervals (SDNN) of the IBI, the power of the low (LF, 0.07-0.14 Hz) and high frequency (HF, 0.15-0.50 Hz) band, and LF/HF ratio were calculated. Log transformation resulted in normal distribution. Correlation between HRV parameters and pain intensity was assessed by Pearson's correlation coefficient.ResultsData from 73 volunteers (44 women) could be analyzed. The mean age was 30 ± 11 years. Compared with baseline, during all heat periods, pain intensity measured by VAS increased from 2 ± 3 mm, 3 ± 5 mm, and 2 ± 4 mm, to 40 ± 20 mm, 42 ± 21 mm, and 44 ± 22 mm, respectively. Log transformed SDNN (lnSDNN) and LF (lnLF) decreased; lnSDNN from 4.0 ± 0.4 to 3.9 ± 0.5, P = 0.002; 4.0 ± 0.4 to 3.9 ± 0.5, P = 0.016; and 4.1 ± 0.4 to 3.9 ± 0.4, P = 0.004, respectively; lnLF from 6.3 ± 1.0 to 6.1 ± 1.2, P = 0.001; 6.4 ± 1.0 to 6.2 ± 1.1, P = 0.019; and 6.5 ± 1.0 to 6.2 ± 1.1, P = 0.020, respectively. No correlation of any HRV parameter with VAS score was found.ConclusionHRV parameters may detect responses to heat pain, but are not suitable to assess pain intensity.Wiley Periodicals, Inc.

21 keywords...

hide…