Hemodynamic Response to Rapid Saline Infusion Compared with Exercise in Healthy Participants Aged 20-80 Years

Abstract

Background and objective: Rapid saline infusion and exercise has been proposed as methods to unmask cardiovascular disease. However, the normal hemodynamic response to rapid saline infusion has not been compared to exercise nor is it known whether the responses are age-dependent.We assessed the hemodynamic response to rapid saline infusion in healthy participants over a wide age-range and compared it to exercise in the same participants.

Methods and results: Fifty healthy participants (young <40 years, n = 16, middle-aged 40-59 years, n = 15, elderly 60-80 years, n = 19) underwent right heart catheterization at rest, during semisupine ergometer exercise at three exercise levels (25%, 50%, and 75% of peak VO₂) and after rapid saline infusion (10 ml/kg at a rate of 150 ml/min). Rapid saline infusion significantly increased pulmonary capillary wedge pressure (PCWP) similarly across all age groups (∆PCWP 6 ± 2; 7 ± 2; 6 ± 4 mmHg for the young, middle-aged and elderly respectively) with no correlation between age and ∆PCWP (r = 0.05; p = 0.74). However, there was a negative correlation between age and ∆stroke volume (SV) as elderly participants had a lower increase in SV following rapid saline infusion (r = 0.44; p = 0.002). On the contrary, exercise-induced significantly larger and age-dependent increases in PCWP (r = 0.58; p < 0.0001). Exercise also caused a larger increase in SV compared with rapid fluid loading (p = 0.0003) CONCLUSION: Unlike exercise, rapid saline infusion caused an age-independent increase in PCWP in healthy adults. Suggesting that age-related impairments beyond passive stiffness have a greater impact on exercise-induced increase in PCWP.

Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT01974557.

Keywords: Exercise; Healthy; Hemodynamics; Saline infusion.