Key result
Lower body muscle tensing, leg crossing, squatting, and the crash position increased systolic blood pressure (e.g., 77 to 104 mmHg; P<0.05) exclusively through increases in cardiac output.
Why the study?
Do physical counter-pressure maneuvers improve hemodynamics during vasovagal reactions in patients with a history of vasovagal syncope?
Do physical counter-pressure maneuvers improve hemodynamics during vasovagal reactions in patients with a history of vasovagal syncope?
p-value: p=<0.05
Physical counter-pressure maneuvers effectively counteract vasovagal reactions exclusively by increasing cardiac output, rather than by increasing peripheral resistance.
May support counter-pressure maneuvers in vasovagal syncope; hypothesis-generating and requires prospective validation.
Tensing of lower body muscles without or with leg crossing (LBMT, LCMT), whole body tensing (WBT), squatting, and sitting with the head bent between the knees ("crash position", HBK) are believed to abort vasovagal reactions. The underlying mechanisms are unknown. To study these interventions in patients with a clinical history of vasovagal syncope and a vasovagal reaction during routine tilt table testing, we measured blood pressure (BP) continuously with Finapres and derived heart rate, stroke volume, cardiac output (CO), and total peripheral resistance using Modelflow. In series A (n = 12) we compared LBMT to LCMT. In series B (n = 9), WBT was compared with LCMT. In series C (n = 14) and D (n = 9), we tested squatting and HBK. All maneuvers caused an increase in BP, varying from a systolic rise from 77 +/- 8 to 104 +/- 18 mmHg (P < 0.05) in series A during LBMT to a rise from 70 +/- 10 to 123 +/- 9 mmHg (P < 0.05) in series B during LCMT. In each maneuver, the BP increase started within 3-5 s from start of the maneuver. In all maneuvers, there was an increase in CO varying from 54 +/- 12% of baseline to 94 +/- 21% in WBT to a rise from 65 +/- 17% to 110 +/- 22% in LCMT in series A. No maneuver caused significant change in total peripheral resistance. We conclude that the mechanism underlying the effects of these maneuvers is exclusively an increase in CO.
No takes yet. Share an insight, caveat, or question.
Krediet et al. (2005) studied Vasovagal syncope (n=44). Physical counter-pressure maneuvers (LBMT, LCMT, WBT, squatting, HBK) vs. Baseline / alternative maneuvers was evaluated on Blood pressure and cardiac output (p=<0.05). Lower body muscle tensing, leg crossing, squatting, and the crash position increased systolic blood pressure (e.g., 77 to 104 mmHg; P<0.05) exclusively through increases in cardiac output.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: