The Prospective Study On Cerebral Protection During Superior Vena Cava Reconstruction Surgery

OBJECTIVE Many studies have showed that with the appropriate indications, superior vena cava (SVC) resection for lung and mediastinal malignancies is technically feasible, and also has a clear benefit on oncological outcomes. SVC removal requires total clamping which may lead to haemodynamics consequences and brain damages. We have investigated the patients who had undergone resection and reconstruction of SVC to evaluate the effect of SVC clamping on haemodynamics changes, cerebral oxygen metabolism and brain functions, and confirm the efficacy of extracorporeal venovenous jugulo-femoral bypass by gradient of pressure, and bring out the deadlines of jugular venous pressure (JVP), mean arterial-jugular vein pressure difference (M-J) and jugular venous oxygen saturation (SjvO₂).Method Patients who had been scheduled for SVC graft from 2004 to 2006 were divided into 2 groups: group N (without SVCS before operation) and group S (with SVCS before operation). Extracorporeal venovenous Jugulo-femoral bypass by gradient of pressure was set up and kept being open during operations for each patient. Anesthesia was induced and maintained withâ…£continuous infusion of propofol, combined withâ…£administrations of fentanyl and vecuronium. ECG, ETCO₂, SpO₂, nasopharyngeal temperature(NPT), arterial pressure and JVP were continuously monitored during operations. Arterial and jugular venous blood samples were taken for analysis of blood gas and glucose concentrations before bypass(baseline); after bypass; 5,15,40 min intra-clamping; 5,60 min after clamping off, together with assays of lactate content before bypass(baseline); 40min intra-clamping; 60 min after clamping off. The systolic arterial -jugular venous pressure difference(S-J), M-J, CaO₂, CjvO₂, Ca-jvO₂, cerebral oxygen uptake rate (ERO₂) and jugular vein-arterial difference of lactate (VADL) were calculated. Follow up the patients after operations.Results A total of 13 patients were enrolled, which were 5 patients in group N and 8 patients in group S. There were no significant differences in arterial blood pressure, PaCO₂, AL, VL, VADL, Ca-jvO₂ during operations. During SVC clamping, PaO₂, arterial base excess(BEa) and jugular venous base excess(BEjv) decreased significantly, compared with those before SVC clamping, but hypoxemia and metabolic acidosis did not exist; JVP and ERO₂ increased significantly, which were 36mmHg(ranged from 22 to 71mmHg) and 48% (ranged from 14% to 75%); SjvO₂, S-J and M-J decreased significantly, which were 55%(ranged from 33% to 80%), 74mmHg(ranged from 39 to 115mmHg), 47mmHg(ranged from 22 to 83mmHg), respectively. The one-side 95% reference values of JVP, M-J and SjvO₂ were 53mmHg, 27mmHg and 32%, respectively. All parameters recovered to baseline after clamping off. Arterial and jugular venous glucose concentrations both increased significantly since SVC clamping, and reached the peak value at 1 hour after clamping off. During clamping, JVP and ERO₂ increased, SjvO₂, S-J, M-J decreased significantly as compared with those before clamping in group N; and in group S, JVP increased during clamping and decreased after clamping(compared with that before clamping, p<0.05), there were no significant differences in ERO₂ and SjvO₂, S-J, M-J during operations except the significant increase of ERO₂ at 5min intra-clamping. Group N had lower JVP at baseline and more increased JVP during clamping than group S. Except those, there had no any significant differences in other parameters between two groups. None of the patients involved any neurologically injured signs and symptoms.Conclusion SVC clamping might lead to the increase of jugular vein pressure and change the balance of cerebral oxygen supply and consumption, especially in patients without SVCS before operations. Arterial pressure and JVP should be monitored continuously, and the arterial and jugular vein blood gas analysis and blood sugar should be investigated intermittently. Higher JVP (>50mmHg), lower M-J (<30mmHg) and SjvO₂ (<32%) should be avoided during SVC clamping. Extracorporeal venovenous jugulo-femoral bypass by gradient of pressure can maintain stable haemodynamics and restrain JVP elevateing, which is safe, simple and efficient for SVC reconstruction surgery.