The Role of Perioperative Ventilation (Gas Exchange) During Intrabdominal Surgery on Cognitive Function: a Randomized Clinical Study

The moderate hyperventilation resulting in hypocapnia as well as hyperoxia are common features of mechanical ventilation during general anesthesia. While mild hyperventilation is routinely advocated in laparoscopic surgical interventions, increased FiO2 is set to reinforce safety of respiratory support. Hypocapnia may cause disturbances of cerebral blood flow due to narrowing of cerebral vessels and a decrease cerebral blood flow. Hypocapnia is particularly injurious to the brain in premature infants. Factors that may predispose the immature brain to such injury include poorly developed vascular supply to vulnerable areas, antioxidant depletion by excitatory amino acids, and the lipopolysaccharide and cytokine effects that potentiate destruction of white matter. Data from neonates clearly suggest that severe hypocapnia after hyperventilation contribute to adverse neurologic outcomes. The use of high concentrations of oxygen can lead to a number of events such as the formation of harmful free radicals and activation of lipid peroxidation, resulting in secondary brain injury due to hyperoxia, particularly after suffering anoxia of the brain in resuscitated victims of sudden cardiac arrest. It is recommended to use the fraction of oxygen to maintain saturation at the level of 94-98% when performing cardiopulmonary resuscitation (CPR), due to the risk of reperfusion injury. These disturbances of gas exchange, yet transient can interfere in cerebral blood flow and therefore mental functions.

The primary aim of this study was the assessment of the impact of intraoperative gas exchange (hypocapnia, hyperoxia and their combinations) on the state of higher nervous activity