Changes in regulators of the circulation in patients undergoing lung surgery

Several vasoactive substances are responsible for control of the circulation. During lung surgery these substances may be influenced either by the technique of anaesthesia or by altered production and elimination. We have studied plasma concentrations of important regulators of the circulation in patients undergoing lobectomy using two different regimens: propofol-low-dose fentanyl-nitrous oxide-vecuronium, tracheal extubation immediately after surgery (group Ia (n = 15)); fentanyl-midazolam-pancuronium, delayed tracheal extubation in the intensive care unit (ICU) (group Ib (n = 15)). We also studied patients undergoing pneumonectomy using fentanyl-midazolam-pancuronium anaesthesia (group II (n = 15)). Plasma concentrations of endothelin-1 (ET-1), atrial natriuretic peptide (ANP), vasopressin, catecholamines (adrenaline, noradrenaline) and 6-keto-prostaglandin F1 alpha were measured. Extensive haemodynamic monitoring was performed using a pulmonary artery catheter. All measurements were carried out after induction of anaesthesia (baseline values), 30 min after one-lung ventilation (OLV) was induced, at the end of surgery, 2 h after surgery in the ICU and on the first day after operation. CVP, PAP and PCWP increased in all groups during OLV but remained increased only in patients undergoing pneumonectomy. CI decreased significantly in the pneumonectomy group but did not differ between both lobectomy groups. SVRI was lowest in the propofol-treated patients and remained highest in the pneumonectomy group. Plasma concentrations of adrenaline and noradrenaline did not change in group Ia, but increased significantly in groups Ib (noradrenaline: from 267 (67) to 496 (91) pg ml-1) and II (adrenaline: from 237 (59) to 681 (210) pg ml-1). Plasma concentrations of ET-1 remained almost unchanged in groups Ia and Ib, whereas they increased in pneumonectomy patients (from 2.63 (0.3) to 6.61 (1.01) pg ml-1). Vasopressin plasma concentrations increased during OLV in all groups; they were lowest in the propofol patients and highest in patients undergoing pneumonectomy (32.2 (10.2) pg ml-1). Plasma concentrations of ANP and 6-keto-prostaglandin F1 alpha increased in all groups during OLV and remained increased only in the pneumonectomy group.