Comparison of Low Versus Normal Flow Anesthesia on Cerebral Oxygenation and Bispectral Index in Morbidly Obese Patients
Condition: Morbid Obesity; Anesthesia Awareness; Anesthesia Complication
MeSH terms: Obesity, Morbid; Intraoperative Awareness
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Regional cerebral oxygen saturation; Bispectral Index (BIS)
Intervention type(s): Device; Device
Intervention description(s): Regional cerebral oxygen saturation is a useful clinical research tool for noninvasive and continuous monitoring of hemodynamic and brain oxygenation. Regional cerebral oxygen saturation (Near-infrared spectroscopy system, NIRS, Cerebral Oximeter) monitoring was performed to all patients.; The most effective method for depth of anesthesia and assessment of sedation is bispectral analysis of mean frequency of electroencephalography. The values of BIS decreases with the deepening of anesthesia.
Other intervention name(s): NIRS (Near-infrared spectroscopy system); BIS
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Prospective Randomized Clinical Study
Masking: Single (Investigator)
Primary purpose: Screening
Keywords: Bariatric surgery; Low flow anesthesia; Bispectral index; Regional cerebral oximetry