Key result
Novel HRV ratio predicts emergence motor movement earlier than BIS with high accuracy.
Why the study?
Variation in R-R interval oscillatory patterns during different depths of sevoflurane anaesthesia lacks quantification and evaluation for estimating anaesthesia depth.
Does the non-rhythmic-to-rhythmic ratio (NRR) accurately estimate depth of anaesthesia compared to the Bispectral Index (BIS) in female patients?
Observational (n=31)
Does the non-rhythmic-to-rhythmic ratio (NRR) accurately estimate depth of anaesthesia compared to the Bispectral Index (BIS) in female patients?
Effect estimate: PK > 0.90
The novel HRV-derived NRR index provides complementary information to BIS for monitoring subcortical motor activity and predicting emergence from sevoflurane anaesthesia.
BACKGROUND: Heart rate variability (HRV) may reflect various physiological dynamics. In particular, variation of R-R peak interval (RRI) of electrocardiography appears regularly oscillatory in deeper levels of anaesthesia and less regular in lighter levels of anaesthesia. We proposed a new index, non-rhythmic-to-rhythmic ratio (NRR), to quantify this feature and investigated its potential to estimate depth of anaesthesia. METHODS: Thirty-one female patients were enrolled in this prospective study. The oscillatory pattern transition of RRI was visualised by the time-varying power spectrum and quantified by NRR. The prediction of anaesthetic events, including skin incision, first reaction of motor movement during emergence period, loss of consciousness (LOC) and return of consciousness (ROC) by NRR were evaluated by serial prediction probability (PK ) analysis; the ability to predict the decrease of effect-site sevoflurane concentration was also evaluated. The results were compared with Bispectral Index (BIS). RESULTS: NRR well-predicted first reaction (PK > 0.90) 30 s ahead, earlier than BIS and significantly better than HRV indices. NRR well-correlated with sevoflurane concentration, although its correlation was inferior to BIS, while HRV indices had no such correlation. BIS indicated LOC and ROC best. CONCLUSIONS: Our findings suggest that NRR provides complementary information to BIS regarding the differential effects of anaesthetics on the brain, especially the subcortical motor activity.
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Lin et al. (2014) conducted an observational in Sevoflurane anaesthesia (n=31). Non-rhythmic-to-rhythmic ratio (NRR) vs. Bispectral Index (BIS) and HRV indices was evaluated on Prediction of first reaction of motor movement during emergence period (PK > 0.90). The non-rhythmic-to-rhythmic ratio (NRR) predicted the first reaction of motor movement during emergence (PK > 0.90) 30 seconds ahead, performing better than HRV indices and earlier than BIS.
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