Effect of non-invasive ischemic preconditioning on nitric oxide/endothelin-1 imbalance and gas exchange impairment following limb ischemia reperfusion: a clinical study / 中国病理生理杂志

ABSTRACT

AIM: To investigate the effects of non-invasive ischemic preconditioning on nitric oxide (NO)/endothelin-1 (ET-1) imbalance and gas exchange impairment following limb ischemia reperfusion in patients undergoing unilateral lower extremity surgery with tourniquet. METHODS: Twenty-seven patients aged 25-65 years, whose tourniquets duration varied from 1 h to 1.5 h and matched American Society of Anesthesiologists Physical Status Ⅰ-Ⅱ, were randomized into two groups a control group (n=14) and a ischemic preconditioning group (IPC group, n=13) in which patients received three cycles of 5 min of ischemia/5 min of reperfusion before tourniquet inflation. Radial arterial blood gas, plasma malondialdehyde (MDA) and NO, serum ET-1 and interleukin-6 (IL-6) were measured just before tourniquet inflation(T_0), 1 h after inflation(T_1), and 0.5 h(T_2), 2 h(T_3), 6 h(T_4), 24 h(T_5) after tourniquet deflation. Meanwhile NO/ET-1 ratio, alveolar-arterial oxygen gradient (P_(A-a)DO_2) and intrapulmonary shunt (Qs/Qt) were calculated. RESULTS: In control group, arterial partial pressure of oxygen (PaO_2) were decreased, while P_(A-a)DO_2 and Qs/Qt were increased significantly at T_4 compared to the baselines at T_0 (P<0.01). Plasma NO levels and NO/ET-1 ratios decreased gradually after tourniquets deflation and statistical significances were observed at T_3 (P<0.01) with a valley at T_4 (P<0.01) and recovered to baselines at T_5. Serum ET-1, IL-6 and plasma MDA began to increase remarkably after T_3 (P<0.05 or P<0.01), peaked at T_4 and dropped slightly at T_5. The changes above-mentioned could be well attenuated by the application of IPC (P<0.05 or P<0.01) except PaO_2 (P>0.05). CONCLUSION: Clinical application of unilateral tourniquet within safe time limit (1.5 h) may lead to limb ischemia reperfusion and further pulmonary gas exchange impairment, which could be partially attenuated by the application of IPC via alleviating NO/ET-1 imbalance.