[Human experiments of metabolism, blood alkalization and oxygen effect on control and regulation of breathing. II: room air exercise test after blood alkalization].

Objective: Basis on the dynamic changes of the ventilation and arterial blood gas parameters to symptom-limited maximum cardiopulmonary exercise testing (CPET), we further investigate the effect of alkalized blood by drinking 5% NaHCO3 on ventilation during exercise.

Methods: After drinking 5% NaHCO3 75 ml (3.75 g) every 5 min, total dosage of 0.3 g/Kg, 5 volunteers repeated CPET. All CPET and ABG data changes were analyzed and calculated. At the same time, CPET and ABG parameters after alkalized blood were compared with those before alkalized blood (control) used paired t test.

Results: After alkalized blood, CPET response patterns of parameters of ventilation, gas exchange and arterial blood gas were very similar (P > 0.05). All minute ventilation, tidal volume, respiratory rate, oxygen uptake and carbon dioxide elimination were gradually increased from resting stage (P < 0.05-0.001), according to the increase of power loading. During CPET after alkalized blood, ABG parameters were compared with those of control: hemoglobin concentrations were lower, CaCO2 and pHa were increased at all stages (P < 0.05). The PaCO2 increased trend was clear, however only significantly at warm-up from 42 to 45 mmHg (P < 0.05). Compared with those of control, only the minute ventilation was decreased from 13 to 11 L/min at resting (P < 0.05).

Conclusion: Even with higher mean CaCO2, PaCO2 and pHa, lower Hba and [H+]a, the CPET response patterns of ventilatory parameters after alkalized blood were similar.