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Counter-pressure maneuvers for syncope management: mechanisms, efficacy, and applicability in children and adults

Despite numerous clinical recommendations for syncope (fainting) management, none are universally effective in preventing recurrence. Counterpressure maneuvers (CPM) are movements frequently recommended to delay or terminate impending episodes, however this is based largely on clinical experience. Research is particularly scarce in children, who are often given adult-based treatment recommendations that are not rooted in evidence. This thesis evaluates the physiological mechanisms, real-world efficacy, and clinical applicability of CPM for syncope management in adults and children. First, a thorough literature review was needed, as the heterogeneity of existing work had not yet been extensively summarized. In Chapter 3, a semi-systematic approach was used to describe known physiological mechanisms and real-world efficacy for CPM, alongside emerging management approaches that exploit skeletal muscle pumping. A link between postural movement and cardiovascular control was identified, therefore in Chapter 4, hemodynamic responses to postural sway were examined. Exaggerated sway improved orthostatic cardiovascular and cerebrovascular stability, demonstrating its potential as a CPM. Chapter 5 further investigates this novel class of CPM. Among dynamic movements (exaggerated sway, gluteal clenching, toe clenching), cardiovascular and cerebrovascular responses to sway were most robust and stable. To comprehensively evaluate dynamic CPM, evaluation in pediatric patients was then required. The presentation of pediatric syncope is described in Chapter 6, to inform both CPM application, and broader diagnostic practices. Pediatric syncope presented with a strong, recognizable prodrome with predictable autonomic triggers, while quality of life (QOL) was reduced in both patients with recurrence, and at initial presentation. Finally, in Chapter 7, responses to dynamic CPM were found to be more stable than clinical maneuvers in a case series of patients with pediatric syncope, and enhanced postural sway was the only movement to improve cerebral blood flow. In a randomised controlled clinical trial examining use of clinical standard CPM in children with syncope during daily living, CPM were effective in reducing the progression of presyncope to a loss of consciousness, while improving QOL. This interdisciplinary thesis provides a comprehensive evaluation of CPM, bridging laboratory evaluation and real-world assessment to advance evidence-based management of the devastating condition of syncope, and improve patient QOL.

Keywords: syncope, orthostatic intolerance, postural sway, counter pressure maneuvers, pediatrics, quality of life