Aims: To determine the accuracy of forearm blood flow (FBF) ratio (flow in infused arm/flow in control arm) to detect unilateral increases in forearm blood flow.
Methods: In nine healthy male volunteers, we measured the effect of infusion of saline into the brachial artery at a rate of 2 ml/100 ml forearm min-1 on FBF ratio during control, mental arithmetic (MAR) and lower body negative pressure (LBNP) at -40 mmHg.
Results: Saline infusion increased FBF ratio from baseline by 115.9+/-17.4, 82.0+/-19.0 and 159.6+/-53.3% for control, MAR and LBNP, respectively (P<0.05 for MAR vs control).
Conclusions: FBF ratio may underestimate unilateral increases in forearm blood flow during simultaneous mental arousal.