Anesthetics and Cerebral Oxygenation in LSG
Condition: Morbid Obesity; Bariatric Surgery Candidate; Anesthesia
MeSH terms: Obesity, Morbid
Study type: Interventional
Phase: Phase 4

Summary: 
      Obesity is a global health issue that affects different organ systems and may cause severe
      health issues. Patients with a BMI > 40 kg/m2 or those with a BMI > 35 kg/m2 with
      accompanying comorbidities are candidates for weight loss surgeries, which are generally
      referred to as bariatric surgeries. Laparoscopic sleeve gastrectomy (LSG) is a restrictive
      bariatric surgery procedure gaining increased popularity in the surgical treatment of morbid
      obesity. However, LSG requires a reverse-Trendelenburg position and prolonged
      pneumoperitoneum. Carbon dioxide pneumoperitoneum increases intracranial pressure (ICP) by
      increasing intra-abdominal pressure and by causing dilation of cerebral vessels through
      carbon dioxide reabsorption. Also, the reverse-Trendelenburg position decreases cardiac
      output and mean arterial pressure (MAP) by reducing cardiac venous return. A Near-infrared
      spectroscopy (NIRS) is a non-invasive technique and provides continuous monitoring of
      regional cerebral tissue oxygen saturation (rSO2).

      Sevoflurane and propofol are widely used for the maintenance of general anesthesia during
      bariatric surgery. Sevoflurane is an efficacious halogenated inhalational anesthetic for
      bariatric surgery because of its rapid and consistent recovery and because it does not cause
      hemodynamic instability because of its low blood solubility. Moreover, it increases global
      CBF through a direct intrinsic cerebral vasodilatory action and, in addition, it might
      improve cerebral oxygenation by decreasing the cerebral metabolic rate of oxygen (CMRO2)
      (luxury perfusion). Propofol can also be a suitable option for the maintenance of anesthesia
      in bariatric surgery. Propofol is a short-acting intravenous anesthetic agent with a very
      good recovery profile, and its elimination half-life and duration of action do not change in
      obese individuals. However, it has been reported that propofol may significantly decrease CBF
      by both suppressing CMRO2 and through a direct vasoconstrictive action. The impact of
      propofol on global CBF is more salient than that on CMRO2, resulting in a decrease in rSO2.
      The aim of the present study was to test the hypothesis that rSO2 is better preserved with
      sevoflurane than propofol in morbidly obese patients who have undergone LSG.
    

Detailed description: 
      All patients were administered 300 mg of oral ranitidine the night before the surgery and 10
      mg intravenous (IV) metoclopramide in combination with 150 mg ranitidine one hour before
      arrival to the operating room. Upon the arrival to the operating room, an electrocardiogram,
      noninvasive blood pressure, SpO2, rSO2 (INVOSTM 5100C oximeter; Covidien, Massachusetts, USA)
      and neuromuscular monitorization (TOF-WatchTM SX, Organon, Dublin, Ireland) were performed on
      the patients. Afterwards, preoxygenation was performed with 4 L/min oxygen (80%) for three
      minutes by using facemasks, and anesthesia was induced with an IV propofol injection (1.5-2.5
      mg/kg of ideal body weight) and an IV bolus administration of remifentanil [1 mcg/kg of lean
      body weight (LBW)] for 30-60 s, and then switched to infusion at 0.25 mcg/kg of LBW/min.
      After the eyelid reflex disappeared, a neuromuscular blockade was performed using rocuronium
      (1.2 mg/kg of LBW), ensuring that the train-of-four count and the post-tetanic count (PTC)
      were both zero, and performed tracheal intubation. Mechanical ventilation was performed with
      a Draeger FabiusTM Plus anesthesia workstation (Draeger Medical, Lübeck, Germany), and
      volume-controlled mechanical ventilation was applied. Breathing gases (oxygen, carbon
      dioxide, sevoflurane) were measured using Draeger ScioTM gas measurement module (Draeger
      Medical, Lübeck, Germany). The tidal volume was set as 7-8 mL/kg of LBW, inspiratory:
      expiratory ratio as 1:2, positive end-expiratory pressure as 5-8 cmH2O, and the respiratory
      rate was determined to obtain an end-tidal carbon dioxide partial pressure (PETCO2) of 32-37
      mmHg. These ventilator settings were not changed throughout the operation. Furthermore, after
      the induction of anesthesia, a radial arterial line was placed in all patients for the
      continuous measurement of mean arterial pressure and intermittent arterial blood gas
      analysis.

      Oxygen/air (fraction of inspired oxygen (FiO2) of 0.40), inspiratory fresh gas flow of 2
      L/min), sevoflurane (1 minimum alveolar concentration [MAC]) and remifentanil IV infusion
      (0.1-0.25 mcg/kg of LBW/min) were used in the Inhalation group for the maintenance of
      anesthesia. Propofol infusion (4-8 mg/kg of total body weight/h), oxygen/air (FiO2 of 0.40;
      inspiratory fresh gas flow of 2 L/min) and remifentanil IV infusion (0.1-0.25 μg/kg of
      LBW/min) were used in the TIVA group. Neuromuscular blockade was performed during the
      operation by rocuronium infusion (0.3-0.7 mg/kg of LBW/h), ensuring that PTC was zero. IV
      normal saline or lactated Ringer's solution at 5-7 mL/kg of LBW was also used for
      perioperative fluid maintenance. Nasopharyngeal temperature was monitored throughout the
      surgery, and the patient temperature (36-37°C) was ensured by using a forced-air warming
      system for the maintenance of intraoperative normothermia during the procedure.

      After anesthesia induction, a neutral head position of the patients was preserved to prevent
      alteration of cerebral venous drainage. Carbon dioxide insufflation was performed with an
      electronic laparoflator using a closed Veress needle technique, and intra-abdominal pressure
      was automatically kept at the desired level (14-16 mmHg) during the surgery. After the
      insufflation of carbon dioxide, the patients were positioned in a 30° reverse-Trendelenburg
      and at a 10° right lateral position.

      At the end of the surgery, the blockade was reversed by administering 4 mg/kg of adjusted
      body weight sugammadex with a PTC of 1-2. All patients were extubated in the beach chair
      position when fully awake. The patients were referred to the recovery unit and monitored for
      50 minutes for complications. In cases where no complications were apparent, the recovery was
      evaluated using the modified Aldrete scoring system. Once the score was ≥9, the patients were
      taken to unit. For postoperative nausea and vomiting, 4-5 mg dexamethasone was used (except
      for diabetic patients on insulin) 90 min before anesthesia induction and 4-8 mg IV
      ondansetron 20-30 min before the end of the operation. For postoperative pain management, 1 g
      IV acetaminophen was administered 20 min after induction and 30 mg IV ketorolac 20 min before
      onset. Then, 1 g IV acetaminophen was administered every 6 h + 50 mg IV dexketoprofen every 8
      h for the first 48 hours. In addition, morphine was administered using a patient-controlled
      analgesia delivery system (demand dose, 20 µg/kg of ideal body weight; lockout time, 6-10
      min; 4 h limit, 80% of the total calculated dosage) for 48 h postoperatively.
    

Intervention name(s): Inhalational anesthetic; Intravenous anesthetic
Intervention type(s): Drug; Drug
Intervention description(s): Oxygen/air (fraction of inspired oxygen (FiO2) of 0.40), inspiratory fresh gas flow of 2 L/min), sevoflurane (1 minimum alveolar concentration [MAC]) and remifentanil IV infusion (0.1-0.25 mcg/kg of LBW/min) were used.Neuromuscular blockade was performed during the operation by rocuronium infusion (0.3-0.7 mg/kg of LBW/h), ensuring that PTC was zero.; Propofol infusion (4-8 mg/kg of total body weight/h), oxygen/air (FiO2 of 0.40; inspiratory fresh gas flow of 2 L/min) and remifentanil IV infusion (0.1-0.25 μg/kg of LBW/min) were used.Neuromuscular blockade was performed during the operation by rocuronium infusion (0.3-0.7 mg/kg of LBW/h), ensuring that PTC was zero.
Intervention MeSH terms: Anesthetics; Anesthetics, Intravenous
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: For the investigation, the patients were randomly assigned to two groups; the Inhalation group including those who received sevoflurane-remifentanil for the maintenance of anesthesia (n = 30) and the TIVA (total intravenous anesthesia) group including those who had propofol-remifentanil infusion for the maintenance of anesthesia (n = 30). The anesthesiologist caring for the patient was aware of the group assignments. The patients were blinded to the group assignments.
Masking: Single (Participant)
Primary purpose: Supportive Care
Keywords: Bariatric; Surgery; Sevoflurane; Propofol; Oximetry