CHANGES IN REGULATORS OF THE CIRCULATION IN PATIENTS UNDERGOING LUNG SURGERY

Several vasoactive substances are responsible for control of the circu lation. During lung surgery these substances may be influenced either by the technique of anaesthesia or by altered production and eliminati on. We have studied plasma concentrations of important regulators of t he circulation in patients undergoing lobectomy using two different re gimens: propofol-low-dose fentanyl-nitrous oxide-vecuronium, tracheal extubation immediately after surgery (group Ia (n = 15)); fentanyl-mid azolam-pancuronium, delayed tracheal extubation in the intensive care unit (ICU) (group Ib (n = 15)). We also studied undergoing pneumonecto my using midazolam-pancuronium anaesthesia (group II (n = 15)). Plasma concentrations of endothelin-1 (ET-1), atrial natriuretic peptide (AN P), vasopressin, catecholamines (adrenaline, noradrenaline) and 6-keto -prostaglandin F-1alpha were measured. Extensive haemodynamic monitori ng was performed using a pulmonary artery catheter. All measurements w ere carried out after induction of anaesthesia (baseline values), 30 m in 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. C VP, PAP and PCWP increased in all groups during OLV but remained incre ased only in patients undergoing pneumonectomy. Cl decreased significa ntly in the pneumonectomy group but did not differ between both lobect omy groups. SVRI was lowest in the propofol-treated patients and remai ned highest in the pneumonectomy group. Plasma concentrations of adren aline and noradrenaline did not change in group Ia, but increased sign ificantly 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)). Plasm a 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 d uring 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 F-1alpha increa sed in all groups during OLV and remained increased only in the pneumo nectomy group.