Contribution of Baroreceptor Function to Pain Perception and Perioperative Outcomes

Abstract

Baroreceptors are mechanosensitive elements of the peripheral nervous system that maintain homeostasis by coordinating physiologic responses to external and internal stimuli. While it is recognized that carotid and cardiopulmonary baroreceptor reflexes modulate autonomic output to mitigate excessive fluctuations in arterial blood pressure and to maintain intravascular volume, increasing evidence suggests that baroreflex pathways also project to key regions of the central nervous system that regulate somatosensory, somatomotor, and central nervous system arousal. In addition to maintaining autonomic homeostasis, baroreceptor activity modulates the perception of pain, as well as neuroimmune, neuroendocrine, and cognitive responses to physical and psychologic stressors. This review summarizes the role that baroreceptor pathways play in modulating acute and chronic pain perception. The contribution of baroreceptor function to postoperative outcomes is also presented. Finally, methods that enhance baroreceptor function, which hold promise in improving postoperative and pain management outcomes, are presented.

Linking Pain Sensation to the Autonomic Nervous System: The Role of the Anterior Cingulate and Periaqueductal Gray Resting-State Networks

“…Importantly, insular activity is associated with top down suppression of baroreflex activity induced by a stress challenge ( Gianaros et al, 2012 ). We suggest that the ANS-associated connectivity between AI and dACC plays a central role in interoception during pain and might also contribute to baroreflex-induced anti-nociception (as reviewed by Suarez-Roca et al, 2018 ). Also, activity in the AI is commonly seen during pain ( Legrain et al, 2011 ).…”

“…One possible mechanism underlying this pain-autonomic interaction is the baroreflex, the negative feedback loop used to maintain stable blood-pressure ( Suarez-Roca et al, 2018 ). This mechanism has been associated with observed reduction in pain perception in healthy controls during spontaneous high blood pressure (during which baroreceptors are activated) and also during mechanical stimulation of baroreceptors ( Edwards et al, 2001 ; Duschek et al, 2007 ; Reyes del Paso et al, 2014 ).…”

Mathematical evaluation of responses to surgical stimuli under general anesthesia

“…Nociception pathways augment responses to noxious stimuli. On the other hand, both descending pain inhibitory system and baroreflex suppress them 4 – 6 . Therefore, these neural pathways interact each other and affect associations between S and R. Both the differential equations developed for Gompertz and logistic functions included the terms representing the suppression of R by the descending pain inhibitory system and baroreflexes, which are 1 − R/R max for logistic function 14 and dA/dS = − kA for Gompertz function 12 , 13 .…”

“…The surgical pleth index (SPI) is also calculated using a linear function, the parameters of which are heart-beat interval and photoplethysmographic pulse wave amplitude 9 . Since these parameters of the autonomic nervous system change according to the descending pain inhibitory system and baroreflex 4 – 6 , it is inevitable that S values are inversely affected by R when evaluating changes in R values in relation to S in clinical settings under general anesthesia (Fig. 1 ).…”

“…Under general anesthesia, the balance between nociception caused by surgical invasiveness and anti-nociception due to anesthetic effects determines the stimulus intensity (S), which induces physiologic responses (R), including activation of the autonomic nervous system and hypothalamic–pituitary–adrenal axis 3 . Conversely, the increases in R activate the descending pain inhibitory system, and suppress hemodynamic responses through baroreflexes 4 – 6 . Therefore, R values are representative of nociception and anesthetic effects, in addition to activation of several neural pathways (Fig.…”