Cognitive dysfunction is the impairment of mental process of perception, memory and information processing which allow the human to acquire knowledge and plan for the future . The etiology of Postoperative cognitive dysfunction (POCD) is unclear and seems to be multifactorial involving a combination of patient, surgical, anesthetic and environmental factors .It can be a manifestation of transient or permanent cerebral injury. While cognitive function tends to improve over months to years postoperatively in affected individuals, some proportion has seemingly permanent cognitive injury .~Most of the studies of POCD, however, have methodological difficulties, as pointed out by Newman and colleagues in their review of more than 40 studies . a major difficulty in trying to compare investigations or establish an incidence of POCD was the diversity in participants, types of surgery and anesthesia, methods of assessment, definition of POCD, and mode of analysis .~The number of tobacco smokers has been decreasing over the last decade in most Western countries, while the percentage of smokers is still increasing in some developing countries . Tobacco smoking is still one of the major causes of mortality and morbidity worldwide . In particular, it is well known that smoking is strongly associated with cardiovascular diseases, pulmonary diseases and cancer. In addition, it is also thought that smoking could increase the risk of poor postoperative outcomes, in ways including impaired wound healing ، infections and cardiopulmonary complications.~The definition of day surgery in Great Britain and Ireland is clear; the patient is admitted and discharged on the same day, with day surgery as the intended management. The term '23-h stay' is used in the United states healthcare system .
Cognitive dysfunction is the impairment of mental process of perception, memory and information processing which allow the human to acquire knowledge and plan for the future . The etiology of Postoperative cognitive dysfunction (POCD) is unclear and seems to be multifactorial involving a combination of patient, surgical, anesthetic and environmental factors .It can be a manifestation of transient or permanent cerebral injury. While cognitive function tends to improve over months to years postoperatively in affected individuals, some proportion has seemingly permanent cognitive injury .