Continuous measurement of blood gasesin vivo by mass spectrography
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Abstract
The application of the mass spectrometer to the continuous monitoring of blood gases in humans is described. At the heart of the system is an intravascular catheter consisting of a cannula impermeable to gas tipped with a membrane whose special gas permeability characteristics permits accurate calibration. Expressions are presented which describe gas flow through the membrane in response to a step increase in gas concentration; characterize thermal effects on gas diffusion and illustrate the effect of the cannula and carrier tubing on steady state gas flow. The system has been successfully employed in the study of arterial nitrogen washout and the determination of human cerebral blood flow by the nitrous oxide technique.
Keywords
Cerebral Blood Flow Nitrous Oxide Jugular Bulb Mass Spectrography Carrier TubingNotation
- A
area (cm2)
- Am
membrane surface area
- Aw
effective water surface area
- a
parameter characteristic of cross-section (cm)
- a′
dummy constant (torr)
- b
dummy constant (torr)
- D
diffusivity (cm2/sec/torr)
- D′
modified diffusivity
- Dm
membrane diffusivity
- Do
reference diffusivity
- Dw
diffusivity in water
- d
differential
- Ep
activation energy (cal/mole)
- F
conductance (cm3/sec)
- Fmem
membrane conductance
- L
length (membrane thickness) (cm)
- Lm
membrane thickness
- Lp
mean free path
- Lw
effective water path length
- M
molecular weight (amu)
- n
number (units, base 10)
- P
gas pressure (torr)
- Pa
average pressure
- Patm
atmospheric pressure
- Po
total pressure
- Pw
gas pressure in water
- P1
pressure on inner surface of membrane
- P2
ion pump pressure
- P33
steady state pressure
- Pt
transient pressure
- R
radius (cm)
- Ro
universal gas constant (2 cal/mole/°K)
- S
ion pump speed (cm3/sec)
- T
temperature (°K)
- t
time (sec)
- V
gas flow (cm3/sec)
- x
distance (cm)
- α′
solubility coefficient (cm3/cm3)
- α
membrane type
- η
viscosity (P)
- λ
dummy constant (1/cm)
- π
numeric (3·14159)
- Σ
summation
- ∞
infinity
- τ
time constant (sec)
Sommaire
L'article décrit une application de la spectrométrie de masse pour la surveillance continue des gaz sanguins chez l'homme. Le coeur du système est un catheter intravasculaire fait d'une canule imperméable aux gaz et munie à une extrémité d'une membrane dont la perméabilité particulière permet des calibrations précises. Des résultats fournissent les débits de gaz à travers la membrane en réponse à des échelons de concentration; ces résultats caractérisent les effets thermiques sur la diffusion gazeuse et illustrent les effets de la canule et des conduits de gaz sur les débits de gaz à l'état stable.
Le système a été utilisé avec succès pour l'étude de la technique de “washout” artériel à l'azote, ainsi que pour l'étude de la circulation cérébrale par la technique de l'oxyde nitreux.
Zusammenfassung
Die Anwendung des Massenspektrometers zur kontinuierlichen Messung der Blutgase des Menschen wird beschrieben. Ein intravaskulärer Katheter ist der Kern des Systems. Er besteht aus einer für Gase impermeablen Kanüle mit einer Membranspitze, deren spezielle Gaspermeabilitätseigenschaften eine genaue Eichung erlauben. Die Beziehungen zwischen dem Gasfluß durch die Membran und einer stufenweisen Erhöhung der Gaskonzentration werden mitgeteilt. Die Temperaturabhängigkeit der Gasdiffusion und der Effekt der Kanüle und der Trägergasschläuche auf den Gasfluß im Steady State wird ebenfalls beschrieben.
Das System wurde in Untersuchungen über das arterielle Auswaschen von Stickstoff und bei der Bestimmung der Hirndurchblutung beim Menschen mit der Stickoxydtechnik erfolgreich angewendet.
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References
- Behnke, A. R., Thompson, R. M. andShaw L. A. (1935) The rate of elimination of dissolved nitrogen in man in relation to fat and water content of the body.Am. J. Physiol.114, 137–146.Google Scholar
- Clark, L. C., Jr. (1956) Monitor and control of blood and tissue oxygen tension.Trans. Am. Soc. Artif. Int. Organs2, 41–48.Google Scholar
- Clauss, R. H., Hass, W. K. andRansohoff, J. (1965) Simplified method for monitoring adequacy of brain oxygenation during carotid artery surgery.New Eng. J. Med.273, 1127–1131.CrossRefGoogle Scholar
- Comroe, J. H. (1965)Physiology of Respiration, p. 18. Year Book Medical Publishers, Inc., Chicago.Google Scholar
- Dushman, S. (1962)Scientific Foundations of Vacuum Technology, pp. 80–90. Wiley, New York.Google Scholar
- Gotoh, F., Meyer, J. S. andEbihara, S. (1966) Continuous recording of human cerebral blood flow and metabolism: Methods for electronic recording of arterial and venous gases and electrolytes.Med. Res. Engng5 (2), 13–19.Google Scholar
- Hass, W. K., Siew, F. P. andYee, D. J. (1968) Progress and adaptation of mass spectrometer to study of human cerebral blood flow.Circulation,38 (VI) 96.Google Scholar
- Kety, S. S., Schmidt, C. F. (1948) Nitrous oxide method for quantitative determinations of cerebral blood flow in man. Theory, procedure and normal values.J. clin. Invest.22, 476–483.Google Scholar
- Robertson, J. S., Siri, W. E. andJones, H. B. (1950) Lung ventilation patterns determined by analysis of nitrogen elimination rates; use of the mass spectrometer as a continuous gas analyzer.J. clin. Invest.29, 577–590.Google Scholar
- Roughton, F. J. W. andScholander, P. F. (1943) Micro gasometric estimation of the blood gases. I. Oxygen,J. biol. Chem.148, 541–550.Google Scholar
- Schmitz, J. V. (1965) Ed.Testing of Polymers, Vol. 1, pp. 394–399. Interscience, New York.Google Scholar
- Severinghaus, J. W. andBradley, A. F. (1958) Electrodes for blood pO2 and pCO2 determinations.J. appl. Physiol.13, 515–520.Google Scholar
- Severinghaus, J. W., Chiodo, H., Eger E. I., Brandstater, B. andHarnbein, T. F. (1966) Cerebral blood flow in man at high altitude.Circulation Res.19, 274–282.Google Scholar
- Van Slyke, D. D. andNeill, J. M. (1924) The determination of gases in blood and other solutions by vacuum extraction and manometric measurement. I.J. biol. Chem.61, 523–573.Google Scholar
- Wilson, R. H., Jay, B. andHolland, R. H. (1961) Gas chromatography: a simple, rapid, reliable method for blood gas analysis.J. Thorac. cardiovasc. Surg.42, 575–579.Google Scholar
- Weissman, M. H. andMockros, L. F. (1969) Oxygen and carbon dioxide transfer in membrane oxygenators.Med. biol. Engng,7, 169–184.CrossRefGoogle Scholar
- Woldring, S., Owens, G. andWoolford, D. C. (1966) Blood gases: Continuousin vivo recording of partial pressure by mass spectrography.Science153, 885–887.CrossRefGoogle Scholar