Summary
Anaesthetized and mechanically ventilated dogs were subjected to five minutes of alveolar hypoxia with FIo2 ranging from 0.08 to 0.20 while pulmonary artery pressure (Ppa), pulmonary wedge pressure (Pwp) and cardiac output (Q) were measured. Hypoxia increased Ppa in all dogs whereas Pwp and Q did not change significantly. Thus pulmonary vascular resistance (PVR) increased by a mean for all dogs of 56 per cent. There was great variation in the absolute increase in Ppa and PVR between animals and these were not statistically correlated with arterial Po2, but highly significant and reproduceable inverse relationships were found for Ppa and PVR against arterial oxygen per cent saturation. The slopes of these responses varied between dogs from -0.013 to -0.144 for PVR and from-0.038 to -0.561 for Ppa. The alveolar-arterial oxygen gradient and the pulmonary shunt fraction were reduced in a similar way with decreasing arterial oxygen per cent saturation, but dead space/tidal volume ratio remained unchanged. Thus the slope of PVR response to hypoxia against arterial oxygen per cent saturation is unique for individual animals. This may reflect functional and likely structural adaptations of the pulmonary vascular smooth muscle.
Résumé
Des chiens anesthésiés et ventilés mécaniquement ont été soumis à des épisodes ďhypoxie alvéolaire de cinq minutes en les exposant à des FIo2 de 0,08, de 0,11, de 0,16et de 0,2; la pression artérielle pulmonaire, la pression pulmonaire coincée (wedge) et le débit cardiaque étaient mesurés lors de ces épisodes.
Ľhypoxie s’est traduite par une élévation de la pression de ľartère pulmonaire chez tous les chiens, alors que la pression pulmonaire coincée et le débit cardiaque n’ont pas changé de façon significative. On a observé une élévation de la résistance vasculaire pulmonaire chez tous les chiens (élévation moyenne de 56 pour cent). ľon a noté de grandes variations dans les augmentations de pression artérielle pulmonaire et de résistance vasculaire pulmonaire, variations sans relation significative avec la Pao2; une relation inverse hautement significative et constante a cependant été trouvée entre la pression de ľartère pulmonaire et la résistance vasculaire pulmonaire et la saturation en oxygène du sang artériel.
Le gradient en oxygène alvéolo-artériel et le shunt diminuaient avec la désaturation en oxygène, mais le rapport espacemort/volume courant demeurait le même. Donc, la courbe représentant la modification de résistance vasculaire pulmonaire secondaire à i’hypoxie en rapport à la saturation artérielle en oxygène est unique chez un animal donné. Ceci peut représenter des adaptations fonctionnelles et possiblement structurales de la musculature vasculaire pulmonaire.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Plumier, P.L. La circulation pulmonaire chez le chien. Arch. Internat, de Physiol.1: 176–213 (1904).
EuLER, V.S. von &Liuestrand, G. Observations on the pulmonary arterial blood pressure in the cat. Acta Physiol. Scand.12: 301–320 (1946).
Lewis, B.M. &Gorlin, R. Effects of hypoxia on pulmonary circulation of the dog. Am. J. Physiol.170: 574–587 (1952).
Lloyd, T.C. Effect of alveolar hypoxia on pulmonary vascular resistance. J. Appl. Physiol.19: 1086–1094 (1964).
Stroud, R.C. &Conn, H.L. Pulmonary vascular effects of moderate and severe hypoxia in the dog. Am. J. Physiol.179: 119–122 (1954).
Tucker, A. &Reeves, J.T. Non-sustained pulmonary vasoconstriction during acute hypoxia in anaesthetized dogs. Am. J. Physiol.228: 756–761 (1975).
Barer, G.R., Howard, P., &Shaw, J.W. Stimulus-response curves for the pulmonary vascular bed to hypoxia and hypercapnia. J. Physiol. (Lond.)211: 139–155 (1970).
Fishman, A.P. Respiratory gases in the regulation of the pulmonary circulation. Physiol. Rev.41: 214–280 (1961).
Fishman, A.P. Hypoxia on the pulmonary circulation. How and where it acts. Circulation Res.38: 221–231 (1976).
Hauge, A. Hypoxia and pulmonary vascular resistance. The relative effects of pulmonary arterial and alveolar Po2. Acta Physiol. Scand.76: 121–130 (1969).
West, J.B. Regional differences in gas exchange in the lung of erect man. J, Appi. Physiol.17: 893–898 (1962).
Grover, R.F., Vogel, K.H., Averill, K.H., &Blount, G.S. Pulmonary hypertension. Individual and species variability relative to vascular reactivity. Am. Heart J.66: 1–3 (1963).
Berry, W.B., McLaughlin, J.S., Clark, W.D., &Morrow, A.G. The effects of acute hypoxia on pressure, flow and resistance in the pulmonary vascular bed. Surgery58: 404–411 (1965).
Daly, I., Michel, C.C., Ramsay, D.J., &Waaler, B.A. Conditions governing the pulmonary vascular response to ventilation hypoxia and hypoxaemia in the dog. J. Physiol. (Lond.)196: 351–379 (1968).
Malik, A.B. &Kidd, S.L. Time course of pulmonary vascular response in dogs. Am. J. Physiol.224: 1–6 (1973).
Thilenius, D.G. &Derenzo, C. Hypoxic pulmonary vasoconstriction in unanaesthetized dogs with constant arterial Pco2 and pH. Clin. Sci.37: 731–737 (1969).
Thilenius, D.G. &Derenzo, C. Effects of acutely induced changes in arterial pH on pulmonary vascular resistance during normoxia and hypoxia in awake dogs. Clin. Sci.42: 277–287 (1975).
Rossing, R.G. &Cain, S.M. A nomogram relating Po2, pH, temperature, and haemoglobin saturation in the dog. J. Appi. Physiol.21: 195–201 (1966).
Viles, P.H. &Shepherd, J.T. Relationship between pH, Po2 and Pco2 on the pulmonary vascular bed of the cat. Am. J. Physiol.215: 1170–1176 (1968).
Bergofsky, E.H. Mechanisms underlying vasomotor regulation of regional pulmonary blood flow in normal and diseased states. Am. J. Med.57: 378–394 (1974).
Sackner, M.A., Will, D.H., &DuBois, A.B. The site of pulmonary vasomotor activity during hypoxia or serotonin administration. J. Clin. Invest.45: 112–121 (1966).
Grant, B.J.B., Davies, E.E., Jones, H.A., &Hughes, J.M.B. Local regulation of pulmonary blood flow and ventilation perfusion ratios in the coati-mundi. J. Appi. Physiol.40: 216–228 (1976).
West, J.B., Dollery, C.T., &Naimark, A. Distribution of blood flow in isolated lung: relation to vascular and alveolar pressures. J. Appi. Physiol.19: 713–724 (1964).
Arborelius, M., Luja, B., &Zauner, C.W. The relative effect of hypoxia and gravity on pulmonary blood flow. Respiration31: 369–380 (1974).
Kato, M. &Staub, N.C. Response of small pulmonary arteries to unilobar hypoxia and hypercapnia. Circulation Res.19: 426–440 (1966).
Hales, C.A., Ahluwalia, B., &Kazemi, H. Strength of pulmonary vascular response to regional hypoxia. J. Appi. Physiol.38: 1083–1087 (1975).
Maloney, J.E., Alcorn, D., Cannata, J., Walker, A., &Ritchie, B.C. Regional vascular response to hypoxia in the lungs of anaesthetized sheep. Austral. J. Exp. Biol. Med. Sci.52: 801–812 (1974).
Hauge, A. &Melmon, K.L. Role of histamine in hypoxic pulmonary hypertension in the rat. II. Depletion of histamine, serotonin and catecholamines. Circulation Res.22: 371–392 (1968).
Mentzer, R.M., Rubio, R., &Berne, R.M. Release of adenosine by hypoxic canine lungtissue and its possible role in the pulmonary circulation. Am. J. Physiol.229: 1625–1631 (1975).
Kadowitz, P.J., Joiner, P.D., &Hyman, A.L. Physiological and pharmacological roles of prostaglandins. Ann. Rev. Pharmacol.15: 285–306 (1975).
Berkov, S. Hypoxic pulmonary vasoconstriction in the rat. The necessary role of angiotensin II. Circulation Res.35: 256–261 (1974).
Tucker, A., Hoffman, E. A., &Weir, E. K. Histamine receptor antagonism does not inhibit hypoxic pulmonary vasoconstriction in dogs. Chest71: 261–262 (1977).
McMurtry, I.F., Hookway, B.W., &Roos, S. Red blood cells play a crucial role in maintaining vascular reactivity to hypoxia in isolated rat lungs. Chest71: 253–255 (1977).
Folkow, B. Haemodynamic consequences of adaptive structural changes of the resistance vessels in hypertension. Clin. Sci.41: 1–12 (1971).
Benumof, J.L. &Wahrenbrock, E.A. Blunted hypoxic pulmonary vasoconstriction by increased lung vascular pressures. J. Appi. Physiol.38: 846–850 (1975).
Author information
Authors and Affiliations
Additional information
Supported by the Canadian Medical Research Council, Grant # MA 5880. Presented in part at the Canadian Anaesthetists’ Society Meeting, June 20-23, 1977.
Rights and permissions
About this article
Cite this article
Forrest, J.B., Fargas-Babjak, A. Variability of the pulmonary vascular response to hypoxia and relation to gas exchange in dogs. Canad. Anaesth. Soc. J. 25, 479–487 (1978). https://doi.org/10.1007/BF03007410
Issue Date:
DOI: https://doi.org/10.1007/BF03007410