ALVEOLAR AIR 117 



observe the duration of the apnoea (and compare with that 

 following less prolonged hyperpnoea) , and the manner of return of 

 normal breathing, look also for evidence of cyanosis. Measure 

 the alveolar CC>2 when breathing returns. Determine for how 

 long hyperexcitability of the motor neurones is evident. When 

 normal conditions become reestablished make a record of 

 the subjective symptoms (the sensations experienced by the 

 observed person). Find out whether any visual, auditory or 

 peripheral skin sensations (numbness, tingling, etc.) were 

 experienced. Finally collect another specimen of urine and 

 determine its total acidity. 



