868.1750—Pressure plethysmograph.
               		
               	 	
               	 	
               	 	               	 	               	 	               	 	               	 	
               	 	
    
        
        (a) Identification.
         A pressure plethysmograph is a device used to determine a patient's airway resistance and lung volumes by measuring pressure changes while the patient is in an airtight box.
     
    
        
        (b) Classification.
         Class II (performance standards).