| Objective: Postoperative delirium (POD) and cognitive decline are common in elderly surgical patients after non-cardiac surgery. Postoperative cognitive dysfunction (POCD) is considered as a mild neurocognitive disorder.No specific etiological factor has been identified for postoperative delirium and cognitive decline.The diagnosis can only be made if the cognitive decline can be corroborated by the results of neuropsychological testing (presurgical and postsurgical).In the last years, many studies demonstrated that the choice of a certain inspiratory oxygen fraction influences not only the intraoperative but also the postoperative outcome of the patient. The optimal inspired oxygen concentration still needs to be evaluated. Previous studies has demonstrated that inspired high concentration of oxygen can enhance and improve the cognitive function, and most recent study in vivo, hyperoxia induced synaptic dysfunction and brain oxidative stress are likely the triggering mechanisms of cognitive dysfunction in Alzheimer's mice.In this study we hypothesized that in the elderly patients undergoing non-cardiac surgery the exposure to fraction of inspired oxygen (FiO2 40%) resulted in an increased incidence of POCD than would be expected for patients receiving high oxygen concentration (FiO2 100%).Methods:Thirty ASA I-III Elderly Patients who were≥60 yr of age, undergoing non-cardiac surgery and requiring general anesthesia were randomized to receive pure oxygen (3-5 min.) at induction time and one single dose of midazolam 2mg/iv followed by an analgesic dose of fentanyl 0.05mg/kg/iv and sleeping dose of Propofol 1-2mg/kg/iv, followed by intubation dose of muscle relaxant (atracurium 0.5 mg/kg) with (FiO2 40%, n=15) and with (FiO2 100%, n=15).During surgery, patients were ventilated with volume-controlled mode. Anesthetic was maintained with an appropriate iv infusion dose of propofol and remifentanyl to kept the patients BP, HR in 25% of their one day preoperative reading and to determine the presence of postoperative cognitive dysfunction (POCD) using the neuropsychological tests battery, anxiety and depression score in short from (one night before and within 7 days after the operation) and intraoperative arterial blood gases analysis, stander ECG, Pulse oximetry, HR, BP and ETCO2 monitoring. Patients were considered to have cognitive dysfunction when a decline of more than 20% in neuropsychological tests battery was found.Results:A total of 30 patients were studied with mean age of (62±7.7), (male=18, female=14). After operation, the risk of POCD in the (FIO2 40%) group was statically no significant difference to the (FIO2 100%) group, the incidence of POCD was in 3 different NTB (total NTB was 9 tests) in 3 different patients in each study group which it was more than 20% of the total NTB, and POCD rate was 18% in each study group, ventilation and gases exchange ABG analysis shown no different change in SaO2 (p=0.34), ETCO2 (p= 0.34) and there was change on PaO2 (p= 00.0).even after adjustment for gender, age, electrolyte, hemoglobin, glucose, Hct, and other potential POCD predictive factors there was also no significant difference. The neuropsychological battery tests showed no different in both groups MMSE (p=0.704).Conclusions:in this study the Exposure to (Fio2 40%) resulted in a non significant deference incidence of postoperative cognitive dysfunction when compared with exposure to (Fio2 100%) in elderly patients undergoing non cardiac surgery. |
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