EEG power spectral density under Propofol and its association with burst suppression,a marker of cerebral fragility

ObjectiveUnder General Anesthesia (GA), age and Burst Suppression (BS) are associated with cognitive postoperative complications, yet how these parameters are related to per-operative EEG and hypnotic doses is unclear. In this prospective study, we address this question comparing age and BS occurrences with a new score (BP_TIVA) based on Propofol doses, EEG and alpha-band power spectral densities, evaluated for SEF₉₅ = 8–13 Hz.Methods59 patients (55 [34–67] yr, 67% female) undergoing neuroradiology or orthopedic surgery were included. Total IntraVenous Anesthesia was used for Propofol and analgesics infusion. Cerebral activity was monitored from a frontal electrodes montage EEG.ResultsBP_TIVA was inversely correlated with age (Pearson r = −0.78, p < 0.001), and was significantly lower (p < 0.001) when BS occurred during the GA first minutes (induction). Additionally, the age-free BP_TIVA score was better associated with BS at induction than age (AUC = 0.94 versus 0.82, p < 0.05).ConclusionWe designed BP_TIVA score based on hypnotics and EEG. It was correlated with age yet was better associated to BS occurring during GA induction, the latter being a cerebral fragility sign.SignificanceThis advocate for an approach based on evaluating the cerebral physiological age (« brain age ») to predict postoperative cognitive evolution.     

Heart rate analysis in 24 patients treated with 150 mg amitriptyline per day

Twenty-four patients treated with 150 mg amitriptyline per day for an episode of major depression underwent a standardized heart rate analysis (HRA) before therapy and after 14 days. The battery of cardiovascular reflex tests included the determination of the coefficient of variation (CV) while resting and during deep respiration, a spectral analysis of heart rate, the heart rate response to standing, and the Valsalva manoeuvre. The results of the initial HRA did not differ from a group of 24 normal control subjects matched for age and sex. On day 14 of treatment the patients showed significantly reduced values of heart rate variability in all tests (P<0.0001), probably due to the anticholinergic side effects of amitriptyline. Heart rate increased form 78.1 to 93.6 bpm on average (P<0.0001). Abnormal CV at rest was registered in 96% of the patients; during deep respiration 29% showed abnormal CV results. An abnormal spectral analysis was found in 100% of the cases (low frequency peak: 42%, mid-frequency peak: 100%, high frequency peak: 79%). The heart rate response to standing was abnormal in 75% and the Valsalva test in 33% of the cases. Eighty-eight percent of the patients fulfilled the criteria of a cardiovascular autonomic neuropathy under the conditions of amitriptyline therapy. As yet, the consequences of these changes for the patients have not been sufficiently elucidated.     

Advances in processing of surface myoelectric signals: Part 1

During sustained voluntary or electrically elicted muscle contractions the surface myoelectric signal is nonstationary and it undergoes progressive changes reflecting the modifications of the motor unit action potentials and their propagation velocity. In particular, during sustained electrical stimulation, the evoked signals show progressive amplitude, time scaling and shape modification. The quantitative evaluation of these changes is important for non-invasive muscle characterisation and may be performed in either the time or frequency domain using parametric and nonparametric spectral analysis as well as alternative methodologies. The paper introduces the detection techniques, reviews and compares the methods of spectral estimation based on FFT and autoregressive models, and discusses their applications and limitations in extracting information from the surface myoelectric signal with particular regard to myoelectric manifestations of localised muscle fatigue during sustained contractions.     

The effects of THA on scopolamine and nucleus basalis lesion-induced EEG slowing

The effectiveness of THA (an anticholinesterae) on scopolamine (0.4 mg/kg) and nucleus basalis (NB) lesion-induced change in neocortical spectral electroencephalography (EEG) were investigated. Scopolamine increased the amplitudes of all the spectral components in waking-immobility. In the movement-related EEG spectral values, only the alpha power was increased. THA 7.5 mg/kg, but not THA 3 mg/kg, could reverse scopolamine-induced amplitude change. NB lesioning increased delta and theta amplitudes, but decreased beta amplitude. Delta amplitude was increased during movement recordings in NB-lesioned rats. THA 7.5 mg/kg and pilocarpine 10 mg/kg, but not THA 3 mg/kg, could partially reverse the increase of delta and theta amplitudes induced by NB lesions. However, the beta power decrease could not be restored with cholinomimetics. This study demonstrates that quantitative EEG activity analysis may reflect the THA-induced restoration of the function of the cholinergic nucleus basalis.     

次氯酸对人血清白蛋白的氧化修饰影响及与高级氧化蛋白产物的关系

目的 研究次氯酸对人血清白蛋白(HSA)的氧化修饰影响及与高级氧化蛋白产物(AOPPs)之间的关系。 方法 有氧条件下在恒定浓度的HSA(60 mg/ml)内加入不同浓度次氯酸(0、1、5、10、20、30、40、50、60 mmol/L，最终浓度)，观察氧化剂对HSA的修饰作用。凝胶排阻色谱法检验HSA氧化修饰结果，在线光谱扫描(190 nm~400 nm)分析修饰产物的光谱特性。结果 次氯酸可氧化修饰人血清白蛋白，其修饰产物主要为二聚体HSA和六聚体HSA。发现次氯酸对HSA单体和HSA二聚体的氧化修饰为一级反应；对诱导生成的AOPPs为准一级反应；而对诱导生成的HSA六聚体则为二级修饰反应。同时发现白蛋白对AOPPs的主要贡献者是六聚体形式的HSA，光谱分析表明HSA聚集体的最大吸收峰发生红移，提示HSA聚集体是由于蛋白中的酪氨酸残基通过氧化交联方式而聚集形成的。 结论 HSA经次氯酸处理后主要发生了蛋白聚集。而对AOPPs的主要贡献者是六聚体形式的HSA。     

Heart rate fluctuations in diabetic patients with cardiac vagal dysfunction: a spectral analysis

The autonomic nervous control of cardiac function during active orthostatic load has been studied by measuring the power spectrum of heart rate fluctuations in 16 insulin-dependent diabetic patients and 14 age-matched control subjects. The patients were subdivided into two groups: 8 with normal respiratory sinus dysrhythmia (RSA+) and 8 with reduced respiratory sinus dysrhythmia (RSA-). In RSA- patients the total power (0.01-0.50 Hz) was significantly reduced compared with control subjects (4.7 versus 15.5 min-2, 2p less than 0.05) and the pattern of heart rate fluctuations was characterized by a relative increase in the low-frequency component (0.01-0.05 Hz) as compared with RSA+ patients and control subjects (45% versus 24% and 27%, both 2p less than 0.01). There was also a significant reduction in the high-frequency component (0.15-0.50 Hz) as compared with RSA+ patients and control subjects (17% versus 36% and 33%, both 2p less than 0.05). During standing, a significant increase in total power was found only in control subjects (2p less than 0.01) and the difference between control subjects, and RSA+ and RSA- patients reached significance (32.2 versus 15.1 and 12.7 min-2, 2p less than 0.02 and 2p less than 0.01). The pattern of heart rate fluctuations in RSA- patients showed no significant change on standing. These results suggest that the reduced overall heart rate variability in diabetic patients with cardiac autonomic neuropathy is associated with a typical heart rate fluctuation pattern.     

Translocation t(6;14) as the Sole Chromosomal Abnormality in Adenoid Cystic Carcinoma of the Base of Tongue

We present an adenoid cystic carcinoma of the base of tongue in a 48-year-old male with a restricted chromosomal alteration by cytogenetic and spectral karyotypic analysis (SKY). SKY and G-banding analyses identified the t(6;14)(q25;q13) as the sole structural aberration in all metaphases analyzed. This finding supports a critical role for this event in the development of this tumor. The implications of chromosome 6q translocation in this case and in previously reported adenoid cystic carcinomas are highlighted and discussed.     

The effect of ventilation on spectral analysis of heart rate and blood pressure variability during exercise

Heart rate variability (HRV) and systolic blood pressure variability (BPV) during incremental exercise at 50, 75, and 100% of previously determined ventilatory threshold (VT) were compared to that of resting controlled breathing (CB) in 12 healthy subjects. CB was matched with exercise-associated respiratory rate, tidal volume, and end-tidal CO(2) for all stages of exercise. Power in the low frequency (LF, 0.04-0.15 Hz) and high frequency (HF, >0.15-0.4 Hz) for HRV and BPV were calculated, using time-frequency domain analysis, from beat-to-beat ECG and non-invasive radial artery blood pressure, respectively. During CB absolute and normalized power in the LF and HF of HRV and BPV were not significantly changed from baseline to maximal breathing. Conversely, during exercise HRV, LF and HF power significantly decreased from baseline to 100% VT while BPV, LF and HF power significantly increased for the same period. These findings suggest that the increases in ventilation associated with incremental exercise do not significantly affect spectral analysis of cardiovascular autonomic modulation in healthy subjects.     

Medical data analysis using microprocessor-based Walsh transformations

The use of Fourier transforms based on orthogonal sinusoidal functions is well established in the analysis of spectral components in noisy medical signals. In this paper the use of Walsh transformations based on orthogonal discrete signals is described for the analysis of ‘slow-wave’ rhythms in the gastro-intestinal tract of mammals. The Walsh transform approach has the advantage that very fast algorithms can be developed since multiplications involving sinusoidal functions are replaced by additions and subtractions. These algorithms are very suitable for simple microprocessors and it is shown that, for determining the frequency of gut rhythms, simple filtering and signal conditioning preceding the microprocessor dispenses with the need for analogue to digital conversion. Hence a very simple digital microprocessing system for the continuous monitoring of gut rhythms has been produced. It has also been extended to provide filtering of signals via forward and inverse Walsh transforms.     

New spectral detection and elimination test algorithms of ECG and EOG artefacts in neonatal EEG recordings

New methods for the detection of ECG and EOG artefacts in the EEG are introduced, which can also be used for the evaluation of the quality of the elimination procedure. These algorithms are based on the estimation of the power or coherence spectrum by means of FFT. The advantage of this method is that the EEG spectrum is monitored by the test algorithm. The spectrum will be plotted if no influence of the ECG and EOG can be found. On the other hand, if artefacts are detected the correction of the EEG time series will be carried out and the spectrum of the corrected EEG time series will be plotted after repeated monitoring by the test algorithm.