Oxidative stress in patients on mechanical ventilation
Introduction. The appearance and intensity of oxidative stress were analyzed in the course of mechanical ventilation and parameters that could point toward potential lung damage. Material and methods. In three time intervals on day 1, 3 and 7 of mechanical ventilation, parameters such as: triglycerides, cholesterol, lactate, serum lactic dehydrogenase, acid-base balance and lipid peroxidation products - thiobarbituric acid reactive substances, were followed in 30 patients with head injuries. Results. A decrease in the level of partial oxygen pressure (PaO2) (p<0.01) and PaO2/FiO2 index (p<0.05) in arterial blood was recorded on day 3 of mechanical ventilation. This was accompanied with an increase in alveolar-arterial difference (AaDO2) (p<0.05), thiobarbituric acid reactive substances (p<0.001) and lactic dehydrogenase (p<0.001) comparing to day 1 of mechanical ventilation. The patients with initial PaO2>120 mmHg, had significant increase of thiobarbituric acid reactive substances and AaDO2 (p<0.05) and fall of PaO2 (p<0.001) on day 3 of mechanical ventilation. Conclusion. Oxidative stress and lipid peroxide production are increased during third day of mechanical ventilation leading to disruption of oxygen diffusion through alveolar-capillary membrane and reduction of parameters of oxygenation.