Comparison of Low Versus Normal Flow Anesthesia on Cerebral Oxygenation and Bispectral Index in Morbidly Obese Patients
Comparison of Low Versus Normal Flow Anesthesia on Cerebral Oxygenation and Bispectral Index in Morbidly Obese Patients
Obesity is a chronic disease that affects quality and duration of life negatively. It's not
 clearly known the effects of low flow anesthesia on cerebral oxygenation with high-risk
 morbidly obese patients. In this study, it was aimed to compare the effects of general
 anesthesia with low flow (0,75 L/min) and normal flow (1,5 L/min) on cerebral oxygenation and
 depth of anesthesia in morbidly obese patients in bariatric surgery.
Obesity is a chronic disease that affects quality and duration of life negatively. It is one
 of the most important health problem in the world along with very common in Turkey.
 Initially, obesity was considered the problem of developed countries but it has become
 inevitable with increase income levels, changes in lifestyles, reduction of energy
 consumption and increase of energy intake in developing countries. Today, the second
 important cause of preventable deaths after smoking is obesity. The World Health Organization
 (WHO) has stated that it will be the most important health problem of the 21st century.
 According to WHO determinations; as of 2008, the prevalence of overweight in the world is 35%
 and the prevalence of obesity is around 11%. The definition of body mass index (BMI) is used
 in defining and classifying obesity. WHO is making the definition of overweight and obesity
 based on body mass index [BMI = Weight (kg) / Height (m2)]. It is called as obesity when the
 calculated value is over 30 kg/m2, morbid obesity over 40 kg/m2 and super obesity over 50
 kg/m2.

 Morbid obesity operations, with effective results on achieving weight loss continuity once it
 has been widely applied in Europe and the United States, have been frequently implemented in
 Turkey as well. With the rising obesity in Turkey, laparoscopic bariatric surgery which has
 low complication rates is preferred.

 Low flow general anesthesia is applied to reduce pollution rates and treatment costs in
 operation rooms. However, the reduction of fresh gas flow should not affect the quality and
 safety of anesthesia management, especially in high risk operations such as morbid obesity
 surgery. Insufflation of abdominal cavity with carbon dioxide during laparoscopic surgery is
 resulted in increased intraabdominal pressure, decreased functional residual capacity and
 pulmonary compliance, increased hypercapnia and systemic vascular resistance. Especially in
 the trendelenburg position it may be difficult to detect cerebral hypoxia as a consequence of
 increased intracranial pressure and decreased cerebral blood flow .

 During general anesthesia, there are several options for monitoring the cerebral condition.
 One of them is cerebral oximetry method which estimates regional tissue oxygenation by
 transcutaneous measurement on the frontal cortex. Near-infrared spectroscopy (NIRS) is a
 monitor used following the adequacy of cerebral perfusion with noninvasive and continuous
 measurement and reflects regional saturation.

 With the development of technology, the safety of anesthesia devices and the advancement of
 monitoring techniques are positively affecting the anesthesia management. The effects of low
 flow anesthesia, which has been used for years and whose positive aspects are well practiced,
 are not clearly known on cerebral oxygenation with high-risk morbidly obese patients. In this
 prospective randomized study, it was aimed to compare the effects of general anesthesia with
 low flow (0,75 L/min) and normal flow (1,5 L/min) on cerebral oxygenation and depth of
 anesthesia in morbidly obese patients in bariatric surgery.
Inclusion Criteria:

 -  American Society of Anesthesiology score I-III,

 -  18-65 years,

 -  BMI> 35

 Exclusion Criteria:

 -  American Society of Anesthesiology IV,

 -  Under 18 years,

 -  Over 65 years,

 -  Obstetric patients,

 -  Uncontrolled diabetes mellitus, cardiovascular and pulmonary disease,

 -  Cerebrovascular disease,

 -  Patients who refused informed consent forms