Use of Heart Rate Variability and Photoplethysmograph-Derived Parameters as Assessment Signals of Radiofrequency Therapy Efficacy for Chronic Pain

Nociceptive and non-nociceptive pain in critical care patients after cardiac surgery

AIM

To assess pain intensity during nociceptive (endotracheal suctioning) and non-nociceptive (body temperature measurement) procedures in critically ill patients after cardiac surgery.

METHODS

A descriptive and cross-sectional design was carried out. The study sample consisted of 60 critically ill patients. The study used the Critical Care Pain Observation Scale, the Behavioural Pain Scale, the Ramsey Sedation Scale and Physiological Parameter Form for data collection. Pain was assessed before, during, and 20 min after endotracheal suctioning and body temperature measurement in the study.

RESULTS

The pain scores were found to be statistically significant differences during endotracheal suctioning and body temperature measurement (p < 0.001). Pain scores were found to be higher during endotracheal suctioning, which is a nociceptive procedure (p < 0.05). Systolic and diastolic blood pressure, heart rate scores were also determined to be statistically higher during endotracheal suctioning (p < 0.05).

CONCLUSION

Pain scores and physiological parameters were found to be higher during endotracheal suctioning, a procedure known to be nociceptive. Critical care nurses are recommended to follow pain assessment protocols.

The Link Between Spinal Cord Stimulation and the Parasympathetic Nervous System in Patients With Failed Back Surgery Syndrome

OBJECTIVES

In patients with chronic pain, a relative lower parasympathetic activity is suggested based on heart rate variability measurements. It is hypothesized that spinal cord stimulation (SCS) is able to influence the autonomic nervous system. The aim of this study is to further explore the influence of SCS on the autonomic nervous system by evaluating whether SCS is able to influence skin conductance, blood volume pulse, heart rate, and respiration rate.

MATERIALS AND METHODS

Twenty-eight patients with Failed Back Surgery Syndrome (FBSS), who are treated with SCS, took part in this multicenter study. Skin conductance and cardiorespiratory parameters (blood volume pulse, heart rate, and respiration rate) were measured during on and off states of SCS. Paired statistics were performed on a 5-min recording segment for all parameters.

RESULTS

SCS significantly decreased back and leg pain intensity scores in patients with FBSS. Skin conductance level and blood volume pulse were not altered between on and off states of SCS. Heart rate and respiration rate significantly decreased when SCS was activated.

CONCLUSIONS

Parameters that are regulated by the sympathetic nervous system were not significantly different between SCS on and off states, leading to the hypothesis that SCS is capable of restoring the dysregulation of the autonomic nervous system by primarily increasing the activity of the parasympathetic system, in patients with FBSS.

Wearable Devices: Current Status and Opportunities in Pain Assessment and Management

INTRODUCTION

We investigated the possibilities and opportunities for using wearable devices that measure physical activity and physiometric signals in conjunction with ecological momentary assessment (EMA) data to improve the assessment and treatment of pain.

METHODS

We considered studies with cross-sectional and longitudinal designs as well as interventional or observational studies correlating pain scores with measures derived from wearable devices. A search was also performed on studies that investigated physical activity and physiometric signals among patients with pain.

RESULTS

Few studies have assessed the possibility of incorporating wearable devices as objective tools for contextualizing pain and physical function in free-living environments. Of the studies that have been conducted, most focus solely on physical activity and functional outcomes as measured by a wearable accelerometer. Several studies report promising correlations between pain scores and signals derived from wearable devices, objectively measured physical activity, and physical function. In addition, there is a known association between physiologic signals that can be measured by wearable devices and pain, though studies using wearable devices to measure these signals and associate them with pain in free-living environments are limited.

CONCLUSION

There exists a great opportunity to study the complex interplay between physiometric signals, physical function, and pain in a real-time fashion in free-living environments. The literature supports the hypothesis that wearable devices can be used to develop reproducible biosignals that correlate with pain. The combination of wearable devices and EMA will likely lead to the development of clinically meaningful endpoints that will transform how we understand and treat pain patients.

Effects of Spinal Cord Stimulation on Heart Rate Variability in Patients With Failed Back Surgery Syndrome: Comparison Between a 2-lead ECG and a Wearable Device

OBJECTIVES

Heart rate variability recordings have the potential to examine the role of the autonomic nervous system. Several wearable devices are nowadays readily available. Up until now, no studies explored whether a wearable device is able to reliably measure a treatment response in chronic pain patients. Therefore, the aim of this study is to evaluate the reliability of a Polar V800 (Polar Electro Oy, Finland) wearable device to accurately measure RR intervals in patients with failed back surgery syndrome (FBSS) during spinal cord stimulation (SCS), as compared with an eMotion 2-lead ECG recording.

MATERIALS AND METHODS

Twenty-two patients diagnosed with FBSS and treated with SCS participated in this study. HRV was measured with a 2-lead ECG registration tool and a Polar V800 during on and off state of SCS. Intraclass correlation coefficients, correlations, limits of agreement, Cronbach's α, and effect sizes were calculated.

RESULTS

Analysis based on the recordings from the ECG and wearable device revealed the same HRV parameters (except for the time-frequency domain) to capture the treatment response of SCS. Parameters that are relevant for measuring the SCS treatment response have strong correlations (r ≥ .82), good ICC values (ICC ≥0.82), acceptable consistency (α ≥ .9), and limited bias.

CONCLUSIONS

Similar pre- to posttreatment changes were revealed between a wearable device and 2-lead ECG with reliable HRV estimates for parameters that are able to capture the treatment changes. This suggests that a wearable heart rate monitor might be a reliable wearable tool for the detection of pre- to post treatment changes of SCS, in patients with FBSS.

Effects of spinal cord stimulation on heart rate variability in patients with Failed Back Surgery Syndrome

Background

Building on the recent finding that chronic pain patients with impaired functioning of the descending nociceptive inhibitory system (DNIS) present lower resting heart rate variability (HRV), this study aims to investigate the impact of Spinal Cord Stimulation (SCS) on HRV in patients with Failed Back Surgery Syndrome (FBSS). More precisely, we hypothesize that SCS influences the DNIS, with increased parasympathetic tone as a consequence, as measurable by HRV analysis.

Methods

Twenty-two patients diagnosed with FBSS and treated with SCS participated in this study. HRV was measured with a 2-lead ECG registration tool during on and off states of SCS. HRV analysis for time, frequency, time-frequency and nonlinear domain parameters was based on a 5-minute recording segment.

Results

The mean heart rate and low frequency power were significantly lower when SCS was activated. HRV, absolute and normalized high frequency power significantly increased during SCS compared to without SCS. The ratio of low frequency/high frequency ratios, as parameter for global sympathetic-parasympathetic equilibrium, significantly decreased when SCS was activated.

Conclusions

When SCS is switched off, patients with FBSS present relatively stronger sympathetic tone and weaker parasympathetic activity. Activation of the SCS, possibly via stimulation of the DNIS, restores this disbalance of autonomic activity.