Fig. 4From: Heart rate variability-derived features based on deep neural network for distinguishing different anaesthesia statesECG data for the proposed method. a–c Raw ECG with visible artifacts, filtered ECG with tiny artifacts, and filtered RR intervals. d–e HF, LF, and ratio of HF/LF. f EACL within the sampling period. HF: high-frequency; LF: low-frequency; HF/LF: high-to-low-frequency ratio; EACL: expert assessment of consciousness levelBack to article page