Respiratory Sinus Arrhythmia in Man: Relation to Right Ventricular Output

Abstract

Freyschuss, Ulla & Melcher, A. Respiratory Sinus Arrhythmia in Man: Relation to Right Ventricular Output. Scand. J. clin. Lab. Invest. 36, 407–414, 1976.

The respiratory effects on heart rate (HR), right ventricular stroke volume (SV_rv), and the pulmonary arterial flow (PAF) have been studied beat-by-beat in 7 conscious, healthy subjects. Tidal volumes (V_t) of 1.0 and 2.0 liters at a breathing rate of 6 cxmin⁻¹ were used as controls. With identical V_t and respiratory rate intrathoracic pressure was affected by (A) negative inspiratory pressure (NIP) of 5 cm of water and (B) with intermittent positive pressure ventilation (IPPV). In the control experiments all subjects exhibited an inspiratory increase in HR (respiratory sinus arrhythmia) as well as in SV_rv. With V_t of 1.0 liter, NIP augmented the inspiratory increase in SV_rv and the respiratory oscillations of PAF. IPPV decreased SV_rv and HR during inspiration. It is concluded that NIP and IPPV affect the SVM_rv and the right heart blood flow. The similar effects on HR and SV_rv suggest a relationship which might be explained by heart-rate-regulating reflexes from the heart.

Key Words:

• Heart rate regulation
• intermittent positive pressure ventilation
• respiration and hemodynamics
• stroke volume