Photoplethysmographic blood presure measurement/ Department of Physiology 1 Photoplethysmographic blood presure measurement C:\Users\Johanka\Desktop\výuka\praktika moje vytvořené prezentace\metody měření TK - praktika perezentace\obrázky\prof_mudr_jan_penaz_csc.jpg Peňáz´s method, volume-clamp method Photoplethysmographic blood presure measurement/ Department of Physiology 2 Principle of continual blood pressure measurement Arterial lumen (finger volume) Pressure in the cuff Control system Constant finger volume pressure Before application of control system Control system: Correction of the pressure in the finger cuff according to the arterial lumen changes. Aim: maintaining of constant arterial lumen through pressure changes in the cuff. application of control system cuff Photoplethysmographic blood presure measurement/ Department of Physiology 3 SBP DBP 150/90 127/92 Photoplethysmographic blood presure measurement/ Department of Physiology 4 Extrasystoles supraventricular ventricular Photoplethysmographic blood presure measurement/ Department of Physiology 5 Orthostatic hypotension 6 Valsalva manoeuvre See videos: oscilometric method of BP measurement https://www.youtube.com/watch?v=Y-NvovSaWTc&t=113s BP changes during smoking https://www.youtube.com/watch?v=J5vPJPfNH3k&t=1s Baroreflex Fast regulation of arterial blood pressure by changes of heart rate and peripheral vascular resistance C:\Users\Johanka\Desktop\výuka\Demonstrace Variabilita-spektrální analýza\obrázky\gr1.jpg peripheral (vascular, sympathetic) branch of baroreflexu Cardiac (parasympathetic) branch Baroreflex heart signal: heart rate arteries signal: blood pressure resistance arteries signal: peripheral resistance CNS: vasomotor centre CNS: kardiomotor centre 10 Baroreflex sensitivity, BRS RR interval BRS: slope SBP R ECG BRSf: slope SBP SBP Blood pressure DBP BRS: change of cardiac cycle caused by SBP change by 1 mmHg [ms/mmHg] Evaluation of cardiac baroreflex function through SBP and heart rate (cardiac cycle) changes 11 Evaluation of BRS Standard(oxford) method: - Application of phenylephrine (vasoconstrictor) E7C22FD0 normal BRS STK STK decreased BRS C:\Users\Johanka\Pictures\další\PhD vtipy a další\15129407_1311358695575392_4095656326193901346_o.jpg Výsledek obrázku pro cat smoking •Physiologically •psychic stress – increased sympathetic activity •Physical exercise – increased sympathetic activity •In old age • •Pathologically •hypertension – decreased baroreceptor sensitivity (atherosclerosis, increased arterial stiffness) •diabetes – neuropathy of autonomic nervous system •Chronic depression (neurogenic) •Heart insufficiency/failure – heart do not response •Transplanted heart - denervation •Myocardial infarction – heart do not response Decreased BRS Signal: time series Beat to beat (for example 5 minutes) •RR interval: 805, 820, 815, 817, 822, 816,….. ms •Hear rate: 70, 73, 68, 65, 67, 71,….. bpm •Systolic blood pressure: 115, 117, 120, 116, 121, 119,….. mmHg 700 800 900 110 120 130 20 40 60 80 100 120 s RR interval R ECG SBP Blood pressure DBP Frequency domain methods – spectral analysis Spectrum Signal in frequency domain Time series Signal in time domain Signal is decomposed in individual frequencies time (s) 50 40 30 20 0 10 0.5 0.4 0.3 0.2 0 0.1 frequency (Hz) Spectrum Signal in frequency domain Time series Signal in time domain Signal is decomposed in individual frequencies time (s) 50 40 30 20 0 10 0.5 0.4 0.3 0.2 0 0.1 frequency (Hz) Frequency domain methods – spectral analysis time (s) frequency (Hz) T=50 s T=10 s T=3 s a=0.5 a=0.3 a=0.2 period T amplitude a frequency f = 1/T f = 1/3 = 0.33 Hz f = 1/10 = 0.1 Hz f = 1/50 = 0.02 Hz 0.5 0.2 0.3 + + = + + = 0.5 0.2 0.3 0.33 0.02 0.1 f = 0,02 Hz f = 0,1 Hz f = 0,33 Hz Spectrum Frequency domain Time domain How the spectrum is formed? Physiological significance – frequency bands High frequency (HF) Intrathoracal pressure changes influencing blood pressure Very low frequency (VLF) Low frequency (LF) Slow hormonal changes, RAS, changes of vascular tonus Respiratory sinus arrhythmia baroreflex band: baroreflex 0.5 0.4 0.3 0 0.1 0.2 0 0,04 0,08 0,12 0 0,0 0,2 Variability source: respiration Variability source: High frequency (HF) Intrathoracic pressure changes influencing blood pressure Very low frequency (VLF) Low frequency (LF) Respiratory sinus arrhythmia baroreflex band: baroreflex 0.5 0.4 0.3 0 0.1 0.2 0 0,04 0,08 0,12 0 0,0 0,2 parasympathetic activity Time lag < 1 s Time lag > 6 s Slow oscillations Fast oscillations High frequency (HF) Very low frequency (VLF) Low frequency (LF) band: 0.5 0.4 0.3 0 0.1 0.2 0 0,04 0,08 0,12 0 0,0 0,2 parasympathetic activity Time lag < 1 s Time lag > 6 s Slow oscillations fast oscillations CNS (n. vagus) Thoracic pressure changes Changes of TPR (sympathetic nerves) Blood pressure signal (270 s) time (s) Sitting, paced breathing Standing, paced breathing Meyer waves (10 s rhythm) respiration sequentions of SBP, DBP and inter-beat intervals time (s) Sitting, paced breathing Standing, paced breathing Spectra of SBP and IBI Sitting, paced breathing Standing, paced breathing 0,1 Hz Sympathetic activity Respiratory frequency vagal activity ↓symp. act., ↑vagal act. ↑ symp. act., ↓vagal act. frequency (Hz) Coherence a BRS frequency (Hz) Sitting, paced breathing Standing, paced breathing 0,1 Hz baroreflex Respiratory frequency coherence: synchronization between signals (correlation on particular frequency)