Utility of photoplethysmography for heart rate estimation among inpatients.

The accuracy of photoplethysmography (PPG) for heart rate (HR) estimation in cardiac arrhythmia is unknown. PPG-HR was evaluated in 112 hospitalised inpatients (cardiac arrhythmias (n = 60), sinus rhythm (n = 52)) using a continuous electrocardiogram monitoring as a reference standard. Strong agreement was observed in sinus rhythm HR < 100 and atrial flutter (bias 1 beat), modest agreement in sinus tachycardia (bias 24 beats) and complete heart block (bias -6 beats) and weak agreement with significant HR underestimation was seen in atrial fibrillation (bias 23 beats). Routine utilisation of PPG for HR estimation may delay early recognition of clinical deterioration in certain arrhythmias and sinus tachycardia.

Pulse photoplethysmographic amplitude and heart rate variability during laparoscopic cholecystectomy: A prospective observational study.

BACKGROUND: Surgical stress affects the autonomic nervous system by increasing sympathetic outflow. One method of monitoring sympathetic activity is pulse photoplethysmographic analysis. From this two indices can be derived - autonomic nervous system state (ANSS) and ANSS index (ANSSi). It has recently been claimed that these indices can be used to measure sympathetic activity in anaesthetised patients, but their validity has not yet been demonstrated. OBJECTIVE: To measure changes in pulse photoplethysmographic indices and determine any agreement with autonomic nervous system modulation of the cardiovascular system in healthy study participants during surgery under general anaesthesia. DESIGN: Prospective observational study. SETTING: Single-centre study based at a tertiary care centre in Milan, Italy. PATIENTS: Healthy patients undergoing general anaesthesia for elective laparoscopic cholecystectomy. INTERVENTIONS: ANSS, ANSSi, and heart rate variability (HRV) were analysed at three main times: baseline, after induction of general anaesthesia, and after pneumoperitoneum insufflation. MAIN OUTCOME MEASURES: The magnitude of changes in photoplethysmographic and HRV indices was measured. The agreement between pulse photoplethysmographic and HRV-derived indices was assessed by Bland-Altman plots. RESULTS: In total, 52 patients were enrolled and their data analysed. Both pulse photoplethysmographic and HRV indices changed during the study phases. An agreement was found between ANSSi and low frequency spectral components of HRV [bias 10.2nu, 95% confidence interval (CI) -13 to 33.4], high frequency spectral components of HRV (bias 6.1 nu, 95% CI -16.3 to 28.6), and low frequency/high frequency ratio (bias 16.1nu, 95% CI -1.4 to 33.5). The agreement was weaker between ANSSI and HRV indices. CONCLUSION: The study endorses the use of pulse photoplethysmographic indices ANSS and ANSSi as surrogates to estimate changes of autonomic modulation of the cardiovascular system in healthy adults during surgery under general anaesthesia.Orcid ID: orcid.org/0000-0002-9616-803X.

Photoplethysmography.

The photoplethysmographic (PPG) waveform, also known as the pulse oximeter waveform, is one of the most commonly displayed clinical waveforms. First described in the 1930s, the technology behind the waveform is simple. The waveform, as displayed on the modern pulse oximeter, is an amplified and highly filtered measurement of light absorption by the local tissue over time. It is optimized by medical device manufacturers to accentuate its pulsatile components. Physiologically, it is the result of a complex, and not well understood, interaction between the cardiovascular, respiratory, and autonomic systems. All modern pulse oximeters extract and display the heart rate and oxygen saturation derived from the PPG measurements at multiple wavelengths. "As is," the PPG is an excellent monitor for cardiac arrhythmia, particularly when used in conjunction with the electrocardiogram (ECG). With slight modifications in the display of the PPG (either to a strip chart recorder or slowed down on the monitor screen), the PPG can be used to measure the ventilator-induced modulations which have been associated with hypovolemia. Research efforts are under way to analyze the PPG using improved digital signal processing methods to develop new physiologic parameters. It is hoped that when these new physiologic parameters are combined with a more modern understanding of cardiovascular physiology (functional hemodynamics) the potential utility of the PPG will be expanded. The clinical researcher's objective is the use of the PPG to guide early goal-directed therapeutic interventions (fluid, vasopressors, and inotropes), in effect to extract from the simple PPG the information and therapeutic guidance that was previously only obtainable from an arterial pressure line and the pulmonary artery catheter.

Contribución al estudio de los efectos sistémicos neurovegetativos del masaje terapéutico mediante el análisis espectral de la variabilidad de la frecuencia cardiaca / Contribution to the study of autonomic systemic effects of therapeutic massage by power spectral analysis of heart rate variability

Objetivo. Analizar las modificaciones que el masaje terapéutico produce en la actividad neurovegetativa sistémica del organismo a través del estudio de la modificación de la actividad autónoma cardiaca. Material y método. Estudio comparativo sobre 15 mujeres de la variabilidad de la frecuencia cardiaca (VFC) (intervalo R-R) obtenida mediante fotopletismografía durante 2 sesiones de 20 minutos de duración: control y masaje. Dicha VFC fue medida en 4 ocasiones diferentes sobre duraciones de 5 minutos cada una. La sesión de masaje consistió en effleurage superficial y presiones deslizadas de gran amplitud. Además, las participantes debían cumplimentar inmediatamente después de la sesión de control y de la de masaje el cuestionario de la escala visual analógica (EVA) de bienestar. Resultados. Para comparar los resultados obtenidos se ha utilizado el t-test pareado de Student y se ha empleado el coeficiente de correlación de Pearson para cuantificar la fuerza de la relación existente entre distintos tiempos en cada uno de los parámetros. Se observa un aumento estadísticamente significativo de la VFC (potencia total) y también un aumento de la actividad parasimpática en la sesión de masaje durante los 5 últimos minutos del mismo (respecto a valores basales), superior a la sesión control. Esta respuesta, sin embargo, tiende a disminuir 5 minutos después de la interrupción del mismo. Finalmente, la puntuación de la EVA de bienestar aumentó significativamente después del masaje, pero su ganancia no se correlaciona con la evolución de las variables fisiológicas. Conclusiones. El masaje aplicado sobre sujetos sanos tiene efecto sobre el sistema neurovegetativo (AU)

Goal: To analyze the changes produced by therapeutic massage on systemic autonomic activity by analyzing the modification of cardiac autonomic activity. Material and methods: A comparative study was performed on 15 women on the variability of heart rate variability (HRV) (RR interval) obtained by photoplethysmography for 2 20-minute sessions: control and massage. HRV was measured at 4 different times for periods of 5 minutes each. The massage session consisted of effleurage massage and wide-ranging sliding pressure. In addition, the participants had to fill out the well-being visual analogue scale (Well Being VAS) questionnaire immediately after the control and massage session. Results: The paired Student’s t-test was used to compare the results obtained. Pearson correlation coefficient was used to quantify the relationship existing between the different times in each one of the parameters. A statistically significant increase was observed in HRV (total power) as well as an increase in parasympathetic activity in the massage session during the last 5 minutes (relative to baseline) compared to control session. However, this response tends to decrease 5 minutes after its interruption/timeout. Finally, the Well Being VAS score shows a significant increase after the massage. However, its gain is not correlated to the changes in the physiological variables. Conclusions: The massage applied on healthy subjects affects the autonomic nervous system (AU)

Photoplethysmographic variability analysis in critical care--current progress and future challenges.

The concept of early goal-directed therapy emphasizes the need for early diagnosis and intervention to achieve better therapeutic outcomes in critical care. There has been rapidly growing interest in the use of the photoplethysmogram (PPG), also known as the "pulse oximetry waveform", as a noninvasive diagnostic tool in this clinical setting. The peripheral PPG exhibits beat-to-beat variability driven by physiological mechanisms such as respiration and sympathetic vascular activity. This paper provides an overview of the current progress towards the application of PPG waveform variability (PPGV) in emergency and intensive care. Studies to date have demonstrated the potential value of PPGV for assessing a range of pathophysiological conditions including blood loss, sepsis and low systemic vascular resistance. Translation of research findings into clinical practice poses several future challenges, including the need for large scale validation studies with appropriate measurement systems, more robust solutions to signal quality issues (such as motion artifacts), and better physiological understanding of the information-rich PPGV.

Photoplethysmography: beyond the calculation of arterial oxygen saturation and heart rate.

In this article, I examine the source of the photoplethysmograph (PPG), as well as methods of investigation, with an emphasize on amplitude, rhythm, and pulse analysis. The PPG waveform was first described in the 1930s. Although considered an interesting ancillary monitor, the "pulse waveform" never underwent intensive investigation. Its importance in clinical medicine was greatly increased with the introduction of the pulse oximeter into routine clinical care in the 1980s. Its waveform is now commonly displayed in the clinical setting. Active research efforts are beginning to demonstrate a utility beyond oxygen saturation and heart rate determination. Future trends are being heavily influenced by modern digital signal processing, which is allowing a re-examination of this ubiquitous waveform. Key to unlocking the potential of this waveform is an unfettered access to the raw signal, combined with standardization of its presentation, and methods of analysis. In the long run, we need to learn how to consistently quantify the characteristics of the PPG in such a way as to allow the results from research efforts be translated into clinically useful devices.

Contour analysis of the photoplethysmographic pulse measured at the finger.

Analysis of the contour of the peripheral pulse to assess arterial properties was first described in the nineteenth century. With the recognition of the importance of arterial stiffness there has been a resurgence of interest in pulse wave analysis, particularly the analysis of the radial pressure pulse acquired using a tonometer. An alternative technique utilizes a volume pulse. This may conveniently be acquired optically from a finger (digital volume pulse). Although less widely used, this technique deserves further consideration because of its simplicity and ease of use. As with the pressure pulse, the contour of the digital volume pulse is sensitive to changes in arterial tone induced by vasoactive drugs and is influenced by ageing and large artery stiffness. Measurements taken directly from the digital volume pulse or from its second derivative can be used to assess these properties. This review describes the background to digital volume pulse contour analysis, how the technique relates to contour analysis of the pressure pulse, and current and future applications.

Value of quantitative photoplethysmography for functional vascular diagnostics. Current status and prospects.

The paper presents recent advances in photoplethysmography (PPG) and the role played by PPG in the noninvasive diagnostics of venous and arterial disease. The technical principles of the new self-calibrating photoplethysmographs are explained. These units allow a quantitative evaluation of all measurement data (e.g. time values, amplitudes, flow rates, blood volume kinetics) and hence a precise analysis of both venous and arterial hemodynamics. In combination with appropriate tests (muscle pump test, vein occlusion test, noninvasive venous pressure test, arterial pulse and pressure test), they are suitable for diagnosing and assessing the severity of vascular disease and monitoring its course and the efficacy of therapy. Now that PPG has gained worldwide acceptance as a routine diagnostic technique for venous disease, its spectrum should be expanded to the arterial side as well.

Pulse oximetry: evolution and directions.

Pulse oximetry monitoring is a relatively recent technique that has been embraced enthusiastically by medical, nursing and paramedical personnel in many clinical situations. Few people, however, have any idea of how it provides the reading of arterial blood saturation. This review performs several functions: it discusses the haemoglobin molecular structure and explains its relation to spectrophotometry, describes the history and principles of pulse oximetry and the nature of the equipment used, and reviews its common uses. It also explores the principles and proposed uses of its lesser known corollary, photoplethysmography.