Usefulness of the perfusion index for monitoring the response to intravenous ketamine infusion therapy in patients with complex regional pain syndrome

Seung-Wan Hong; Min-Sik Hwang; Jae Hun Kim; Minjung Kim; Seong-Hyop Kim

doi:10.1111/papr.13215

Usefulness of the perfusion index for monitoring the response to intravenous ketamine infusion therapy in patients with complex regional pain syndrome

Pain Pract. 2023 Jun;23(5):535-542. doi: 10.1111/papr.13215. Epub 2023 Mar 7.

Authors

Seung-Wan Hong¹, Min-Sik Hwang¹, Jae Hun Kim¹, Minjung Kim¹, Seong-Hyop Kim^{1

2

3}

Affiliations

¹ Department of Anaesthesiology and Pain Medicine, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.
² Department of Medicine, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Seoul, Korea.
³ Department of Infection and Immunology, Konkuk University School of Medicine, Seoul, Korea.

PMID: 36840382
DOI: 10.1111/papr.13215

Abstract

Background: This study was performed to compare the perfusion index (PI) between affected and unaffected limbs in patients with complex regional pain syndrome (CRPS); it also evaluated the usefulness of the PI for monitoring the response to intravenous ketamine infusion therapy in such patients.

Methods: In total, 46 patients with CRPS in one arm or leg were enrolled in this study. The PIs of the unaffected (PI_Control ) and affected (PI_CRPS ) limbs were simultaneously evaluated before and after treatment.

Results: PI_CRPS was significantly lower than PI_Control at all time points. The change in PI from immediately before to 30 min after intravenous ketamine infusion therapy (T_Before and T_{30 min} , respectively) in the affected limb was significantly correlated with the change in visual analog pain scale (VAS) between the two time points (r = 0.646, p < 0.001). The area under the curve for the changes in VAS and PI_CRPS between T_Before and T_{30 min} was 0.928. The optimal threshold value for the change in PI_CRPS between T_Before and T_{30 min} , to distinguish responders with a ≥ 50-point reduction in VAS score from nonresponders, was 22.60% with a sensitivity of 0.811 (95% CI: 0.774-0.848) and a specificity of 0.889 (95% CI: 0.848-0.930). Thirty-one patients showed a ≥ 50-point reduction in VAS score [67% (95% CI: 54%-80%)] and 15 patients showed a < 50-point reduction in VAS score [33% (95% CI: 20%-46%)]. Thirty patients showed an increased PI ≥ 22.60% [65% (95% CI: 50%-78%)] and 16 patients showed an increased PI < 22.60% [35% (95% CI: 22%-50%)]. Twenty-seven patients had a ≥ 50-point reduction in VAS score and an increased PI ≥ 22.60% [59% (95% CI: 44%-74%)]. Eleven patients had shown a < 50-point pain reduction in VAS score and increased PI < 22.60% [24% (95% CI: 13%-37%)].

Conclusion: The PI significantly differed between affected and unaffected limbs in patients with CRPS. The PI may be useful for monitoring the response to intravenous ketamine therapy in patients with CRPS.

Keywords: complex regional pain syndrome; ketamine; perfusion index.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Analgesics / therapeutic use
Complex Regional Pain Syndromes* / drug therapy
Complex Regional Pain Syndromes* / etiology
Humans
Infusions, Intravenous
Ketamine* / therapeutic use
Perfusion Index

Substances

Ketamine
Analgesics

Associated data

CRiS/KCT0005976