PHASE AND FREQUENCY COORDINATION OF CARDIAC-FUNCTION AND RESPIRATORY-FUNCTION

ECG and respiration (by nose thermistor sensor) were measured in 160 h ealthy volunteers under resting conditions. Frequency analysis allowed to distinguish fast (center frequency approximate to 0,25 Hertz), med ium (center frequency approximate to 0,1 Hertz) and slow waves (center frequency approximate to 0,05 Hertz) of heart rate variability. The f ast waves are related to respiratory sinus arrhythmia, which mirrors p arasympathetic tone and the slow waves are mainly connected with the s ympathetic nervous activities, whereas medium waves are influenced by both the sympathetic and the parasympathetic nervous system. Simultane ously we calculated the heart - respiration coupling by recording a to tal of approximate to 18.000 respiratory cycles as well as the time fr om the R-peak to the onset of the next inspiration. Three distinct pea ks of coincidence are related to afferents discharging in the isometri c systolic phase (peak 1), to the baroreceptor afferents in the great arterial vessels (peak 2) and afferents excited in the relaxation or d iastolic filling phase (peak 3), respectively. The pulse-respiration q uotient (PRQ) represents the state of the autonomic nervous system (AN S): Ergotropic conditions lead to an individual's PRQ with no special preference, whereas during trophotropic conditions the PRQs exhibit a preference for a 4:1 ratio. The latter is shown by measurement under r esting conditions. The above-mentioned cardio-respiratory interactions could be used for a multidimensional assessment of autonomic function s. Differentiation between ergotropy and trophotropy, sympathetic or p arasympathetic arousal, sympathicotony and parasympathicotony is possi ble using these parameters and allows to study the autonomic activity from different viewpoints. Moreover, such a multidimensional descripti on of the ANS might prove to be a valuable instrument for the clinical investigation of the state of the autonomic nervous system.