Effects of increased left atrial pressure, endotoxemia and pulmonary air embolism on the measurement of extravascular lung thermal volume
Kubo, K.; Kobayashi, T.; Fukushima, M.; Shibamoto, T.; Sakai, A.; Ueda, G.
Nihon Kyobu Shikkan Gakkai Zasshi 26(8): 825-832
1988
ISSN/ISBN: 0301-1542 PMID: 3060636 Document Number: 321445
To determine the accuracy of thermal-dye indicator dilution measurements in pulmonary edema, we compared this technique with lung lymph balance in increased left atrial pressure, endotoxemia and pulmonary air embolism, using anesthetized sheep with lung fistulae. We also judge the degree of injury of lung vessels in these pulmonary edemas according to lung lymph concentration of indocyanine green (ICG) which is bound to blood proteins and remains in the intravascular compartment in normal condition. We produced pulmonary edema by elevation of left atrial pressure (IP, n = 5), intravenous infusion of Escherichia coli endotoxin of 1 .mu.g/kg (ETX, n = 5) and infusion of air of 1.2 ml/min through a thin tube (ID, 0.3 mm) into the main pulmonary artery over 3 h (Air, n = 4). Left atrial (Pla) and pulmonary artery pressures (Ppa), lung lymph flow (.ovrhdot.Qlym), lymph/plasma protein concentration ratio (L/P), lung lymph protein clearance (Clym), and extravascular lung thermal volume (EVLTV) were measured every 30 min. In the IP group, Pla was elevated by 10 mmHg. .ovrhdot.Qlym significantly increased from 3.5 .+-. 0.7 of baseline to 8.7 .+-. 2.0 ml/20 min with a significant decrease in L/P. EVLTV significantly increased from 7.0 .+-. 1.2 of baseline to 11.5 .+-. 1.0 ml/kg. During a late period (3-5 h after endotoxin) in ETX group, Pla and Ppa did not change, though .ovrhdot.Qlym significantly increased from 3.7 .+-. 0.6 to 8.2 .+-. 1.1 ml/30 min with a significant increase in L/P and Clym. However, EVLTV slightly decreased from 8.6 .+-. 1.4 to 7.7 .+-. 2.6 ml/kg. In the Air group, Ppa significantly increased from 16.7 .+-. 1.6 to 23.2 .+-. 1.4 mmHg during air infusion, and quickly returned to baseline to recovery. Pla showed no changes. .ovrhdot.Qlym significantly increased from 3.6 .+-. 0.4 to 7.5 .+-. 1.7 ml/30 min during air infusion and to 8.9 .+-. 2.0 ml/30 min during recovery with increases in L/P and Clym. The degrees of increased L/P and Clym were greater in ETX group than in Air group. EVLTV remarkably decreased from 7.5 .+-. 2.6 to 2.2 .+-. 0.7 ml/kg during air infusion and significantly increased by 10.0 .+-. 1.6 mg/kg during recovery. The concentration of ICG in lung lymph did not change in the IP and Air groups, though it remarkably increased in ETX group. These data suggest that the thermal-dye technique underestimates the degree of lung edema in endotoxin-induced pulmonary edema and in the presence of pulmonary emboli, and that the degree of injury of lung vessels may be greater in endotoxin-induced lung than in lung injury caused by air embolism.