The Effect of PEEP and Intraabdominal Pressure Levels on Cerebral Oxygenation Morbidly Obese.
Condition: Unspecified Effect of Air Pressure
Study type: Observational

Summary: 
      Background: Study was designed to determine the effect of zero (ZEEP) and 5 mmHg positive end
      expiratory pressure (5PEEP) on cerebral oximeter levels in morbid obese patients whose
      undergoing laparoscopic sleeve gastrectomy. Second outcome is to investigate the effect of
      intraabdominal pressure changes on cerebral oxygen values in LSG.

      Method:18-65 yo, ASA2-3 status, 60 morbid obese patients which planned SLG under general
      anesthesia were included.Two patient in Group 5 PEEP were excluded because of the
      haemodynamic instability during procedure. Patients were divided into 2 groups which was
      ventilated with no PEEP (Group ZEEP)(n=30) and 5 cmH2O PEEP levels (Group5 PEEP)(n=28). All
      patients were use right hand dominant. Near infrared spectroscopy probes were applied to both
      frontal cerebral area of all patiens and measured rSO2 values. IAP were measured
      transvesically in all groups. Datas were recorded as basal, after induction of anesthesia, 5
      minute before insufflation(5BI), 5 minute after insufflation(5BA), 15, 30, 45, 60 minute
      after induction, 5 minute before desufflation(5BD) and 5 minute after desufflation(5AD) time
      periods. Invasive arterial pressures, cerebral oxymeter values, 5 lead electrocardiography,
      peripheral oxygen saturation, end tidal carbondioxide, peak inspiratory pressures, intra
      abdominal pressure, were recorded time periods in all groups. Arterial blood sample analysed
      on 5BI,5AI, 5AD periods.
    

Detailed description: 
      60 morbidly obese patients which planned sleeve gastrectomy procedures under general
      anestesia (ASA 2-3 status) were included in this study. Patients were devided into 2 groups
      which was ventilated with no positive end expiratory pressure (Group 5PEEP n=30), and 5 cmH2O
      positive and expiratory pressure (Group ZEEP n=30). All the patients were right hand
      dominate.Two patient in Group 5 PEEP were excluded because of the haemodynamic instability
      during procedure.

      Exclusion criteria: Documented coronary or periferally arteryel disease, unregulated diabetes
      mellitus, history of smoking, symptoms of bowel or urinary bladder obstruction, preoperative
      systolic pressure grater than 170 mmHg, diastolic arterial pressure grater than 90mmHg,
      pregnancy, anemia (haematocrit levels under %30), and symptoms of increased intracranial
      pressure, significant stenosis of the carotid arteries. In all anesthetised patients were
      monitorised with 3 leads electrocardiography(ECG), pulse oxymetry (sPO2),invasive blood
      pressure(IBP), end-tidal carbondioxide (EtCO2),intraabdominal pressure levels (IAP)with
      intravesical urinary catheter, peak inspiratuar pressure (PIP), laparoscopic pressure (LP),
      regional cerebral oxygen saturation(rSO2) continuously. rSO2 values were measured with near
      infrared spectroscopy (NIRS) technique by cerebral oximeter (INVOS 4100, Somanetics,
      Covidien) measurements recorded as basal values; after induction; before 15 minute of
      insufflation; after 15 minute of insufflation; 30, 45, 60 after induction; before 15 minute
      of desufflation; after 15 minute of desufflation. Arterial blood samples were collected and
      performed before 15 minute of insufflation; after 15 minute of insufflation; after 15 minute
      of desufflation. Partial oxygen pressure(PaO2), partial carbondioxide pressure( PaCO2),
      peripheric oxygen saturation (SaO2), bicarbonate (HCO3), aside- base status (pH), haematocrit
      (Htc) haemoglobin(Hb) levels were recorded and evaluated those three time periods which
      explained above. Cerebral oximeter was placed skin of the patients forehead after clean
      special skin-prep pad. The skin sensors were applied on the right and left sides of the
      forehead. The medial margin of the sensor was at the midline of the forehead and lateral
      margin 2 cm above the eyebrows.

      After induction of anesthesia a 20 gauge intraarterial cannula was placed in to left radial
      artery and recorded 5 minute periods.

      Anesthetic procedures and measured parameters were administered same ways except of PEEP
      levels.

      All patients were received midazolam 2mg intravenously (IV) about five minute before
      induction. Anesthesia was induced with fentanyl( 1-3 mcgr/kg), propofol (2-3mg/kg),
      rocuronium (0,6 mg/kg). After intubation anesthesia was maintained with sevoflurane 2-3 %
      volume (to improve MAC 1 levels for sevoflorane). Remifentanyl was given continuously during
      surgery at a rate of 0.05-2 mcg/kg/min) (IV). Rocuronium was administered at a rate of 30 min
      time intervals during the anesthesia. Sugammadex was administered at the end of the surgery
      for reversing the neuromuscular blockage. Tramadol 1mg/kg, 40 mg meperidine and paracetamol
      1g were administered for postoperative analgesia after trochars were removed. The
      concentration of volatile anesthetic was monitored with GE anesthesia machine. Patients were
      ventilated 6 lt/dk gas flow (50% oxygen with 50% air mixture). 6-8 ml/kg tidal volume,
      inspiration/ expiration rate 1/2 was maintained. Respiratory rate was 8-12 breaths. EtCO2 was
      kept within the range 35-45 mmHg. 5mmHg PEEP was administered in Group 5 PEEP, no PEEP was
      administered Group ZEEP. Fluid balance and blood replacement was maintained with %0.09 NaCl
      and ringer or colloid(Voluven Fresenius Kabi, Graz, Austria) solution IV. Body temperature
      was maintained normothermic by upper body forced air and warming pads. Laparoscopic pressure
      was maintained at below 14mmHg throughout the operation. Intraabdominal pressure was measured
      in mililitres of mercury through a Foley bladder catheter with 3 stopcocks connected to
      infusion set and pressure transducer. IT connected to the electronic monitor of anesthesia
      machine. (Datex -Ohmeda S/5 Compact, GE Healthcare, Finland) . After clamping the tube 100 ml
      Saline solution was injected in to the bladder. The transducer was replaced and zeroed to the
      urinary bladder level whenever the position changes throughout the procedure. Oscillation
      test was performed before started the IAP measurements. This measurements was performed into
      two position: basal, after induction, before insuflation, after insuflation, before
      desuflation, after desuflation values were measured in supine position; 30min, 45 min, 60min
      measurements in 30 degree reverse trendelenburg position (head of the bed elevated to 30
      degree). Intraabdominal hypertension was defined as an IAP of 12 mmHg or higher, according to
      the consensus definations of the World Society for The Abdominal Compartment Syndrome.

      After end of the operation all the anesthetic agents stopped and 4 mg/kg sugammadex was
      performed IV.
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        60 morbidly obese patients which planned sleeve gastrectomy procedures under general
        anesthesia (ASA 2-3 status) were included in this study. Patients were devided into 2
        groups which was ventileted with no positive end expiratory pressure(Group 5PEEP n=30), and
        5 cmH2O positive and expiratory pressure (Group ZEEP n=30). All the patients were right
        hand dominate.
      
Keywords: Obesity; intraabdominal pressure; cerebral oxymeter; sleeve gastrectomy; laparoscopy