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Hypoxic Pulmonary Vasoconstriction in Man: Effects of Hyperventilation
Author(s) -
BINDSLEV L.,
JOLINCARLSSON Å.,
SANTESSON J.,
GOTTLIEB I.
Publication year - 1985
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1985.tb02251.x
Subject(s) - medicine , hyperventilation , hypoxic pulmonary vasoconstriction , vasoconstriction , anesthesia , hypoxia (environmental) , cardiology , oxygen , chemistry , organic chemistry
The pulmonary vasoconstriction response to hypoxia was studied in eight anaesthetized supine subjects. One lung was made hypoxic while the other was ventilated with 100% oxygen. This was achieved by separating the tidal gas‐distribution to the lungs by means of a double‐lumen tracheal catheter. The hypoxic pulmonary vasoconstriction (HPV) response was estimated from the blood flow diversion away from the hypoxic lung. Blood flow distribution between the lungs was calculated from the regional expired carbon dioxide production, assuming regional carbon dioxide production to be proportional to blood flow. The subjects were studied during six different conditions. Firstly, when ventilated with 100% oxygen to both lungs at a Paco 2 of about 6 kPa. Secondly, with 100% oxygen to the left lung and 5% oxygen in nitrogen to the right (test) lung. The ratio between carbon dioxide output from right and left lung was calculated. These measurements were repeated during two states of hyperventilation (Paco 2 of about 4.5 kPa and 3.5 kPa, respectively) with and without hypoxia (conditions 3–6). During normoventilation, blood flow distribution between the lungs was equal. During hypoxia, blood flow distribution to the hypoxic lung decreased by 35% of the prehypoxic value. Furthermore, a decrease in arterial oxygen tension from 51.5 ± 4.5 to 11.5 ± 2.1 kPa was observed. During excessive hyperventilation (Paco 2 3.2 ± 0.2 kPa), blood flow distribution to the hypoxic right lung decreased by only 10% of its prehypoxic value. A further decrease in arterial oxygen tension to 8.5 ± 1.8 kPa was observed. This decrease in Pao 2 was possibly due to an increased venous admixture caused by an abolished HPV response. It is concluded that hyperventilation counteracts hypoxic pulmonary vasoconstriction in man.