| Changes in pulse wave transit time variability after interscalene brachial plexus block placement |
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Eun Joo Choi1, Jung A Lim1, Chang Hyuk Choi2, Dong Hyuck Kim1, Sungbin Jo1, Jonghae Kim1 |
1Department of Anesthesiology and Pain Medicine, Daegu Catholic University Medical Center, Daegu Catholic University School of Medicine, Daegu, Republic of Korea
2Department of Orthopedic Surgery, Daegu Catholic University Medical Center, Daegu Catholic University School of Medicine, Daegu, Republic of Korea |
Corresponding author:
Jonghae Kim, Tel: +82-53-650-4979, Fax: +82-53-650-4517,
Email: usmed12@gmail.com; usmed@cu.ac.kr
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Received: 5 December 2024 • Revised: 25 March 2025 • Accepted: 28 April 2025
*Eun Joo Choi and Jung A Lim contributed equally to this study as co-first authors. |
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| Abstract |
Background
The pulse wave transit time (PWTT) increases with decreased vascular tone resulting from sympathetic blockade caused by regional anesthesia. It oscillates, exhibiting variability due to the interaction between the autonomic nervous and cardiovascular systems. We hypothesized that interscalene brachial plexus block (ISBPB) placement increases the PWTT and reduces the low-frequency power of PWTT variability (LF).
Methods
Fifty-six patients receiving an ISBPB were analyzed. The PWTT was defined as the difference in milliseconds (ms) between the R peak of the electrocardiogram and the peak of the second-derivative photoplethysmographic waveform. The LF was calculated by integrating from 0.04 to 0.15 Hz on the power spectrum obtained from fast Fourier transform. The two variables were collected during 5 min before the end of acclimatization (baseline), between 5 and 10 min after block needle insertion, and between 15 and 20 min after block needle insertion.
Results
The PWTT increased significantly (P < 0.001) from baseline (mean [SD]: 155.3 [16.7] ms) to 5–10 min post-needle insertion (166.9 [15.4] ms) (mean difference [MD]: 11.6, 95% CI [9.2, 14.0], P < 0.001) and 15–20 min post-needle insertion (165.6 [16.1] ms) (MD: 10.3, 95% CI [7.3, 13.2], P < 0.001). The natural log-transformed LF (lnLF) decreased significantly (P < 0.01) from baseline (1.539 [0.560] ln[ms2/Hz]) to 5–10 min post-needle insertion (1.341 [0.617] ln[ms2/Hz]) (MD: –0.198, 95% CI [–0.356, –0.040], P < 0.01) and 15–20 min post-needle insertion (1.396 [0.548] ln[ms2/Hz]) (MD: –0.144, 95% CI [–0.274, –0.013], P = 0.03).
Conclusions
The post-ISBPB decrease in lnLF and increase in PWTT may be attributable to ISBPB-induced sympathectomy. |
| Key Words:
Autonomic nervous system; Brachial plexus block; Fourier analysis; Pulse wave analysis; Regional anesthesia; Sympathectomy |
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