Serum doxapram and respiratory neuromuscular drive in normal man.

To investigate the means by which doxapram affects the control of ventilation, ventilatory function and P have been related to serum doxapram concentration during a 45-min infusion of doxapram hydrochloride in 7 healthy, conscious subjects under normoxic conditions. Serum doxapram concentrations increased during the infusion: 1.88, 2.48, 3.42, and 3.97 µg/ml after 5, 10, 30 and 45 min, respectively. The majority of significant changes in the measurements from the baseline were observed at 30 and 45 min: $${{\dot V}}_{{E}}$$ , V, P, P/end-tidal CO tension, V/T and blood pressure were increased, and end-tidal CO tension was decreased. No significant changes in Pdi, T/T, $${{\dot V}}_{{E}}$$ /P, and P/(V/T) were observed. A correlation was observed between the % increases in P and $${{\dot V}}_{{E}}$$ and doxapram concentration, and between $${{\dot V}}_{{E}}$$ and P. The doxapram-induced increase in $${{\dot V}}_{{E}}$$ appears to be caused by increased neural drive. It is related to the serum drug concentration in the conscious subject. [ABSTRACT FROM AUTHOR]