This device requires the use of thoracic muscles to maintain prescribed air pressure in the lungs for brief periods. It consists of a clear plastic hollow cylinder fitted with a mouthpiece, a spring-loaded piston, and a small vent for escaping air when exhalation into the mouthpiece displaces the piston

Lippitt, M. W.

Reed, J. H.

English

NASA Technical Reports Server

C11 
July 1964	 Brief 64-10108 
NASA TECH BRIEF
	
H 
This NASA Tech Brief is issued by the Technology Utilization Division to acquaint 
industry with the technical content of an innovation derived from the space program. 
Device Induces Lungs to Maintain Known Constant Pressure 
	
Brass Disc	 Helical Spring	 Plastic (Tetrafluoroethylene)	 Plastic Cap 
	
N	 Piston x / 
gq//4f_ I INO I __  
'7M Plastic 
is	 T4
rV//A 
Mouthpiece
/	
///////A
Machine Screw-Closes Port Provided 
Stainless Steel Calibration Screw	 for Pressure Calibration
Transparent Plastic

Cylinder 
The problem: To design a device that requires a 
human subject to use his thoracic muscles to maintain 
a prescribed air pressure in his lungs for periods of 
at least 15 seconds. Maintenance of a known constant 
pressure in the lungs is useful for evaluation of the 
orthostatic reflex of the cardiovascular system and 
also as a periodic exerciser of this reflex. Liquid-
filled manometers which are used for these purposes 
have the disadvantage that the subject can maintain 
a prescribed air pressure with the cheek muscles alone 
without employing the thoracic muscles. In addition, 
these manometers are relatively large and fragile, and 
their liquid contents can be easily spilled. 
The solution: A device consisting of a hollow 
cylinder of clear plastic fitted with a mouthpiece, a 
spring-loaded piston, and a small vent through which 
air escapes when the subject's lung exhalation into the 
mouthpiece displaces the piston by a desired amount.
How it's done: When the subject breathes into the 
mouthpiece, the exhaled-air pressure exerted against 
the spring-loaded piston causes it to move a distance 
proportional to the applied pressure. The device is 
calibrated for the required pressure, 40 millimeters 
of mercury for example, so that when the subject's 
exhaled air applies a slightly greater pressure, the 
piston moves past the vent in the side of the cylinder 
and the air flows out to the atmosphere. The size 
of the vent is chosen to prevent exhaustion of the air 
in the subject's lungs for up to 30 seconds of test and 
to force him to use his thoracic muscles rather than 
his cheek muscles to maintain the required pressure. 
An annular line on the piston coincides with a refer-
ence line on the clear-plastic cylinder when the piston 
moves just past the vent. The subject is instructed to 
maintain this alignment to avoid overpressure which 
would occur if the piston were allowed to move too 
far past the vent.
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19640000029 2020-03-11T17:06:32+00:00Z
Notes:	 3. For further information about this innovation 
1. Compared to liquid-fulled manometers, this device 	 inquiries may be directed to: 
is smaller, more rugged and reliable, is much easier
	
Technology Utilization Officer 
to use, and assures a more nearly constant pressure	 Manned Spacecraft Center 
with less mental effort from the subject. 	 P.O. Box 1537 
Houston, Texas, 77001 
Reference: B64-10108 
2. The device can be fabricated for various pressures
	
Patent status: NASA encourages the immediate 
and air flow rates by proper vent placement and
	
commercial use of this invention. Inquiries about 
obtaining rights for its commercial use may be made 
cylinder bore size. By placing a number of vents  
along the cylinder wall, a sliding ring can be
	
to NASA Headquarters, Washington, D.C. 20546. 
arranged to uncover only one vent for selection of
	 Source: M.W. Lippitt and J. H. Reed 
the desired pressure.	 (MSC-50)


Device induces lungs to maintain known constant pressure

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