the individual virtually instantaneously and is of particular utility because the monitoring device allows calculation of the stroke volume of an individual during the performance of medical procedures such as open heart surgery and other times at which prior art devices were incapable of functioning the device 30 further allows the effects of various procedures such as induction of anesthesia sternotomy dissection going on bypass and returning from bypass to be quantitatively measured and analyzed still further monitoring device 30 may be utilized to monitor the individual 18 during oxygen inhalation and cardiovascular rehabilitation programs such as an oxykinetic exercise program referring to the schematic illustration of fig6 the cardiac performance monitoring device 30 together with transmitter 62 is utilized in order to monitor individual 18 during such exercise the individual 18 is supplied an oxygen air mixture from tank 70 through mask 72 the individual 18 then engages in intermittent periods of exercise the intensity and duration of such exercise being controlled by the magnitude of the individual 39 s stroke volume calculated by monitoring device 30 as illustrated in fig7 calculation of the individual 39 s stroke volume may further be utilized to control the flow rate and oxygen concentration of.