Veldhoven, Lisa

Background In models of congestive heart failure, carotid body denervation decreases ventilatory oscillations, thereby increasing ventilatory stability. Low‐dose dopamine can acutely blunt carotid body chemosensitivity assessed by a reduction of the hypoxic ventilatory response (HVR), but whether it affects ventilatory stability was previously unknown. We hypothesized ventilatory oscillations [as assessed by coefficient of variation of tidal volume (%CV V t ) and breathing frequency (%CV F b )] would be reduced when the carotid chemoreceptors were desensitized by low‐dose dopamine. Methods Healthy adults (n=20, 6F/14M, 31±2 years) rested quietly for 5‐min and breath‐by‐breath ventilation was measured during normoxia under 2 IV infusion conditions: 1) saline, 2) an individualized dose of dopamine (1‐4 ug/kg/min) shown to result in a nadir HVR. Results Dopamine infusion increased breathing frequency (13±1 to 14±1 breaths/min, p=0.03) with no change in mean tidal volume (740±65 to 700±68 mL, p=0.18). Infusion of dopamine in young healthy adults increased ventilatory oscillations (%CV V t : saline = 21±2, dopamine = 30±4, p=0.01; %CV F b : saline = 17±1, dopamine = 21±2, p=0.07). There was no relationship between the decrease in HVR and the increase in ventilatory oscillations (V t : r=0.15, p=0.54; F b : r=0.33, p=0.16). Conclusion Contrary to our hypothesis, IV dopamine (at an individualized dose that attenuates HVR) significantly increases ventilatory oscillations in healthy subjects. These data suggest the effect of low‐dose dopamine on ventilatory oscillations in healthy adults is in contrast to that seen with carotid body denervation in disease. Funding : NIH DK090541