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The effects of general anesthesia on human skin microcirculation evaluated by wavelet transform
Svein Aslak Landsverk1, Per Kvandal, Alan Bernjak
1Department of Anesthesiology, Ulleval University Hospital, Oslo, Norway. s.a.landsverk@medisin.uio.no
Anesthesia and Analgesia
|September 28, 2007
Summary
General anesthesia alters skin microcirculation by reducing sympathetic and myogenic activity, while increasing respiratory oscillations. Wavelet transform analysis of laser Doppler flowmetry signals reveals these changes, offering insights into anesthesia
Area of Science:
- Physiology
- Anesthesiology
- Biomedical Engineering
Background:
- Laser Doppler flowmetry (LDF) time-frequency analysis using wavelet transform identifies characteristic oscillations in skin microcirculation.
- These oscillations correlate with cardiac, respiratory, myogenic, sympathetic, and very slow wave activities.
- Endothelium-dependent vasodilation, modulated by acetylcholine, influences very slow oscillations.
Purpose of the Study:
- To investigate the impact of general anesthesia on microcirculatory vasomotion and sympathetic activity using LDF and wavelet transform.
- To assess changes in specific oscillatory components of the LDF signal under general anesthesia.
Main Methods:
- Eleven patients undergoing faciomaxillary surgery were studied.
- Skin microcirculation was measured using LDF on the forearm.
- Iontophoresis with acetylcholine and sodium nitroprusside was employed before and during general anesthesia (propofol, fentanyl, midazolam).
- LDF signals were analyzed with wavelet transform to assess frequency-specific oscillations.
Main Results:
- General anesthesia significantly reduced spectral amplitudes in the very slow (0.0095-0.021 Hz), sympathetic (0.021-0.052 Hz), and myogenic (0.052-0.15 Hz) frequency bands.
- A significant increase in the respiratory frequency band (0.15-0.6 Hz) was observed during general anesthesia.
- No significant effect of general anesthesia on the difference between acetylcholine and sodium nitroprusside responses in the very slow oscillation band.
Conclusions:
- General anesthesia suppresses microcirculatory oscillations related to sympathetic and myogenic activity, as well as endothelium-modulated components.
- Iontophoretic data suggest no specific effect on endothelial function under anesthesia in this context.
- The observed increase in respiratory frequency oscillations is attributed to mechanical ventilation.
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