Relaxation versus fractionation as hypnotic deepening: do they differ in physiological changes?

After rapid hypnotic induction, 12 healthy volunteers underwent hypnotic deepening with relaxation or with fractionation (without relaxation) in a random latin-square protocol. Electroencephalographic occipital alpha activity was measured, low-resolution brain electromagnetic tomography was performed, and hemodynamics (stroke volume, heart rate, cardiac output, mean arterial blood pressure, forearm arterial flow and resistance) were monitored in basal conditions and after deepening. After relaxation, both forearm flow (-18%) and blood pressure (-4%) decreased; forearm resistance remained unchanged. After fractionation, a forearm flow decrease comparable to that recorded after relaxation was observed, but blood pressure remained unchanged, leading to an increase of forearm resistance (+51%). Central hemodynamics did not change. Alpha activity increased in the precuneus after fractionation only. In conclusion, both relaxation and fractionation have vasoconstrictor effects, but fractionation is also associated with an increase in peripheral resistance.

Measured outcomes with hypnosis as an experimental tool in a cardiovascular physiology laboratory.

The authors detail their multidisciplinary collaboration of cardiologists, physiologists, neurologists, psychologists, engineers, and statisticians in researching the effects of hypnosis on the cardiovascular system and their additions to that incomplete literature. The article details their results and provides guidelines for researchers interested in replicating their research on hypnosis' effect on the cardiovascular system.

Hypnosis prevents the cardiovascular response to cold pressor test.

To highlight the effects of hypnotic focused analgesia (HFA), 20 healthy participants underwent a cold pressor test (CPT) in waking basal conditions (WBC) by keeping the right hand in icy water until tolerable (pain tolerance); subjective pain was quantified by visual scale immediately before extracting the hand from water. The test was then repeated while the participants were under hypnosis and underwent HFA suggestions. Cardiovascular parameters were continuously monitored. Pain tolerance was 121.5+/-96.1 sec in WBC and 411.0+/-186.7 sec during HFA (p < 0.0001), and visual rating score 7.75+/-2.29 and 2.45+/-2.98 (p < 0.0001), respectively. CPT-induced increase of total peripheral resistance was non significant during HFA and +21% (p < 0.01) in WBC. HFA therefore reduced both perception and the reflex cardiovascular consequences of pain as well. This indicates that hypnotic analgesia implies a decrease of sensitivity and/or a block of transmission of painful stimuli, with depression of the nervous reflex arc.