Hypnotic Hallucination of Body Heating Modifies Splanchnic Circulation: Haemodynamic and Ultrasonographic Pilot Study in Normal Volunteers

In previous experience we demonstrated that in highly hypnotizable subjects (highs) it is very easy to produce through hypnotic suggestion of heat a real and measurable increase of temperature and of blood flow in body segments. Aim of the present paper is to ascertain whether this is plausible for splanchnic vessels too. In 5 healthy volunteers aged 27.4±4.0 years, cardiac output, upper limb blood flow, mesenteric diameter, flow and mean flow velocity, and portal vein diameter and flow velocity were measured by bioimpedence, ultrasonography and LASER-Doppler in usual conditions of consciousness (pre-hypnosis) and during hypnotic suggestion of body heat. Following hypnotic body heating, splanchnic vasodilation (+59% in mesenteric blood flow, p<0.01; +16% in diameter; mean flow velocity +43%) was observed, paralleling upper limb flow, while portal vein diameter decreased by 25% (p<0.001) and portal vein mean flow by 30% (p<0.001) probably to maintain a constant pressure in the hepatic district in the context of the so-called hepatic arterial buffer response. As a consequence of abdominal and peripheral vasodilation, 9% reflex rise in heart rate and 15% in stroke volume were observed, leading to increase of cardiac index in comparison to baseline (+16%). Following reflex hyperdynamic status, systolic blood pressure insignificantly tended to increase from 111.8±21.9 mmHg to 116.0±13.7 mmHg (+6%). Hypnotic heating is therefore associated to splanchnic arterial vasodilation, a condition that reminds of other physical hyperdynamic conditions. The mental image of body heating therefore produces real and measurable physical effects that can be detected with the tools of physiologists.