Surfactant protein B and RAGE increases in the plasma during cardiopulmonary bypass: a pilot study.

Surfactant derived protein B (SPB) and plasma receptor for advanced glycation end products (RAGE) have been proposed as markers of lung injury. The former is produced specifically by pneumocytes while RAGE production is present in several body tissues. Cardiopulmonary bypass (CPB) generates a transient lung injury. We measured SPB and RAGE in plasma before surgery and after CPB, as well as 24 h and 48 h later. We analysed plasma samples from 20 subjects scheduled for elective coronary artery bypass grafting. We performed a quantitative analysis of plasma levels of RAGE and SPB mature form (8 kDa) by ELISA and a semi-quantitative analysis of SPB immature form (~ 40 kDa) by Western blotting. Surgery procedures were uneventful. After CPB RAGE median (75th-25th interquartile difference) increased from 633 (539) pg·mL⁻¹ to 1,362 (557) pg·mL⁻¹ (p < 0.01), while mature SPB increased from 5,587 (3,089) ng·mL⁻¹ to 20,307 (19,873) ng·mL⁻¹ (p < 0.01). RAGE and mature SPB returned to normal values within 48 h. This behaviour was confirmed when RAGE and SPB were normalised for protein content. Parallel changes were observed for immature SPB. Plasma RAGE and SPBs are sensitive and rapid markers of lung distress.

[Hypoxemia after heart surgery. An exception or a normal development?]. / Ipossiemia dopo cardiochirurgia. Eccezione o normalità?

The course of respiratory exchange through arterial blood gas analysis after coronary bypass-grafting and valvular replacement has been investigated in a cohort of 62 patients. Arterial blood gases were measured at baseline (the day before surgery), and then 1, 2, 3 and 9 days after surgery; in a subset of 18 patients, randomly selected from the same population, pulmonary function tests were also performed at baseline and repeated on day 9. Arterial blood gases showed a remarkable prevalence of hypoxaemia (as defined as arterial PaO2 less than 60 mmHg): 31% on the first, 50% on the second, and 40% on the third post-operative day; anemia and desaturated mixed venous blood were also prominent findings during the first two days. Arterial PO2 resulted higher afterward, although its mean value then was significantly lower than baseline (81.5 +/- 8.8 vs 93.1 +/- 9 mmHg, p less than 0.005). Pulmonary function tests evidenced widespread restrictive changes, with alterated thoraco-pulmonary mechanics (loss of more than 40% of vital capacity and one second forced expiratory flow) and parenchimal lung damage (residual volume and CO diffusion capacity decrease). Some differences in PaO2 course between coronary patients and valvular patients have been releaved; the mean basal PaO2 value of valvular was significantly lower then the other one (86.7 +/- 10.8 vs 94.7 +/- 10.9, p less than 0.05).

Improvement of cardiac function by allopurinol in patients undergoing cardiac surgery.

Allopurinol reduces formation of cytotoxic free radicals during myocardial ischemia/reperfusion in animals. To evaluate the effect of allopurinol on cardiac performance and metabolism after coronary bypass in humans, we divided 33 patients into two groups: 15 patients (controls) received no allopurinol and 18 patients received 200 mg allopurinol intravenously (i.v.) 1 h preoperatively. Hemodynamic measurements were made with a triple-lumen thermodilution pulmonary artery catheter before cardiopulmonary bypass (CPB), 30 min after completion of CPB and 6 h later in the intensive care unit (ICU). A catheter placed into the coronary sinus was used for blood sampling for measurement of lactate and creatine phosphokinase MB. Peripheral blood was obtained for measurement of xanthine oxidase activity (XO), uric acid, and thiol groups. A myocardial biopsy was taken for measurement of thiol group content and XO before CPB and after heparin neutralization with protamin (a few minutes after CPB). Treated patients had better recovery of cardiac output (CO) and left ventricular stroke work (LVSW) 30 min and 6 h after completion of CPB than did controls. Allopurinol significantly reduced plasma XO. Plasma concentrations of uric acid increased significantly in both groups 30 min after completion of CPB, but the increase in controls was greater (p < 0.02) than with allopurinol. Thiol group levels increased (p < 0.05) only in controls. Our results demonstrate improvement of cardiac function in coronary artery bypass surgery with allopurinol that is related to its metabolic effects consistent with protection against XO catalyzed free radical-mediated injury.