Effects of Two Different Stepwise Lung Recruitment Maneuvers on Patient Hemodynamics During Laproscopic Surgery
Condition: Recruitment
Study type: Interventional

Summary: 
      Pneumoperitoneum with CO2 insufflation during laparoscopic surgery elevates the intrathoracic
      pressure through the elevation of the diaphragm, which in turn decreases the lung compliance
      .Alveolar recruitment (AR) refers to the dynamic process of opening collapsed lung units by
      increasing transpulmonary pressure. It increases the area of ventilated lung parenchyma, thus
      improving gas exchange and arterial oxygenation .During lung recruitment, a transient
      increase in transpulmonary pressure induced by an intentional increase in airway pressures,
      results in an increase in intrathoracic pressure and a decrease in venous return, leading to
      a decrease in left ventricular end-diastolic areas and in stroke volume.
    

Detailed description: 
      Pneumoperitonium for laproscopic surgery usually result in decrease total respiratory
      compliance due to cranial shift of the diaphragm. Alveolar recuirtment is applied hopefully
      to minimize lung atlectasis and open collapsed alveoli to maintain arterial oxygenation. The
      anantomical proximity of lungs and heart within the chest means that any increase in
      intrathoracic pressure could have major effect on cardiovascular functions.Up to now, far too
      little attention has been paid to the decrease in left ventricular performance owing to
      fluctuation within the- chamber within chamber system-that preciptate stroke volume and
      cardiac output reduction during recruitment maneuvers.Up to our knowledge, the effect of ARM
      on patient heamodynamics is still unclear. in this study, we will compare two different
      recruitment maneuvers on patient haemodynamics during laproscopic surgery.Therefore this
      study is designed to investigate the effect of two individualized recruitment maneuvers
      during anethesia for laproscopic surgery to encourage best arterial oxygenation with the
      least haemodynamic compromise. Accordingly we assume that recruitment by incremental stepwise
      PEEP by 5cmH2o with pressure controlled ventilation may be associated with better stroke
      volume stability without haemodynamic alteration in comparison to incremental stepwise tidal
      volume by 4ml/kg during volume controlled ventilation.

        -  Pre-oxygenation for 5 minutes will be done in all patients and they will receive 0.02
           mg/Kg midazolam, 1-2 μg/Kg fentanyl, 2-2.5 mg/kg Propofol slowly IV until loss of verbal
           contact. atracurium 0.5 mg/kg to facilitate proper placement of endotracheal tube. All
           patients will be mechanically ventilated using volume control mode (VC mode) with tidal
           volumes of 6 ml/ PBWT, with respiratory rate 12 breath per minute (bpm) and PEEP 5 cmH2O
           to keep end tidal Carbone dioxide (ETCO2) at 30-35 mmHg. Anaesthesia will be maintained
           in all patients using (1-1.5) minimum alveolar concentration (MAC) of Sevoflurane in
           O2/air mixture with FIO2 (0.4).Patients will be randomly assigned to one of two equal
           groups, according to computer-generated randomization sequence:

        -  group 1 (RM TV ): Recruitment maneuver with tidal volume .

        -  group 2 (RM PEEP): Recruitment maneuver with positive end expiratory pressure.

      Group 1 (RM TV):

      The ventilation protocol consisted of volume controlled mechanical ventilation, FiO2 0.4,
      inspiratory-to-expiratory (I:E) ratio at 1:2, and respiratory rate (RR) set to normocapnia
      (end-tidal CO2 partial pressure between 35 and 40mmHg, TV 6 mL/kg PBW and 5 cmH2O PEEP.

      RMs were conducted under volume controlled ventilation with initial settings of a limit of
      peak inspiratory pressure at 40cmH2O, TV at 6 mL/kg PBW (PBW = 50.0+0.905*((height in
      cm)-152.4) for men, and = 45.5+0.905*((height in cm)-152.4) for women) , RR at 7 breaths/min,
      PEEP at5 cmH2O, and I:E ratio at1:1. The TV was then increased by steps of 4 mL/kg PBW until
      plateau airway pressure (Pplt) was 40 cmH2O, after which 3 breaths were allowed. Finally, the
      limit of peak inspiratory pressure, TV, RR, and I:E ratio were reset at values equal to those
      preceding the RM. The ventilation protocol could be changed at any time when concerned about
      patient safety.

      Group 2 (RM PEEP):

      The ventilation protocol consisted of volume controlled mechanical ventilation, FiO2 0.4,
      inspiratory-to-expiratory (I:E) ratio at 1:2, and respiratory rate (RR) set to normocapnia
      (end-tidal CO2 partial pressure between 35 and 40mmHg, TV 6 mL/kg PBW and 5 cmH2O PEEP.

      RMs was conducted under pressure controlled ventilation so ventilation technique will be
      changed, pressure-control mode will be started and inspiratory time is increased to 50%
      (inspiratory: expiratory ratio will be set to 1:1). Peak airway inspiratory pressure (Ppeak)
      will be initially set to 20 cmH2O for three breaths, and then PEEP will be increased in steps
      from 5 to10 cmH2O for five breaths, from 10 to 15 cmH2O for seven breaths, from 15 to 20
      cmH2O for ten breaths while Ppeak increased to 40 cmH2O and will be maintained for three more
      breaths. Following ARM, volume control will be re-established using Vt 6 mL/kg and step-wise
      reductions in PEEP from 20 to 15 cmH2O for three breaths,and then to 5 cmH2O until the end of
      recruitment maneuver.Monitoring:

      Hemodynamic monitoring : stroke volume (SV), stroke volume variation (SVV), stroke volume
      index (SVI), cardiac output (COP), cardiac index (CI), systemic vascular resistance (SVR),
      systemic oxygen delivery (DO2) and oxygen delivery index (DO2I) will be measured by Cardiac
      output non-invasive monitor (ICONTM, OSYPKA medical cardiotronic GMBH, Elixir, Germany).
      Heart rate (HR), mean arterial blood pressure (MAP), and arterial oxygen saturation (Sao2)
      will be measured using HP monitor.

      Respiratory monitoring : calculated lung compliance (dynamic compliance = TV / (peak airway
      pressure - PEEP)(static compliance = TV /(plateau pressure -PEEP) , peak airway pressure and
      plateau pressure, calculated alveolar dead space((1.135*(Paco2-Eco2)/(paco2-0.005)), driving
      pressure ( plateau pressure - PEEP) and Horowitz index ((Pao2 / Fio2)*100).

      Basel hemodynamic variables will be obtained before endotrachial intubation (T0), Basel
      respiratory variables will be obtained just after endotracheal intubation(T0), Then
      allvariables will be obtained after endotrachial intubation (T1), after insuflation(T2),
      Intraopertive (T3a= at 1st hour intraopertive, T3b= at 2nd hour intraopertive, T3c= at 3rd
      hour intraopertive), after desuflation of the abdomen (T4), at end of surgery(T5). At each
      time point, the haemodynamic parameters will be recorded as follow: just before the alveolar
      recruitment maneuver (ARM), after 2 minutes of ARM, after 5 minutes of ARM.

      Rescue strategies:

        1. Intraoperative hypoxemia (Spo2< 92%): rescue will be primarily performed by ↑Fio2 by 0.1
           till reach 100%.

        2. Intraopertive hypotension (systolic blood pressure < 90 mmHg):

             -  Abort ARM strategy if warranted.

             -  Fluid administration ( 500 cc hydroxyethyl starch or 500 cc blood transfusion if
                indicated).

             -  Noradrenaline infusion (0.1mg/kg/min) is the last resort. Postoperative follow up:
                hemodynamic variables will be monitored at arrival to post operative care unit
                (PACU) (P1), and after 2 hours (P2).Also chest x-ray to exclude postoperative
                complications like atlectasis or pneumothorax .
    

Intervention name(s): Recruitment maneuver with tidal volume (RM TV); Recruitment maneuver by PEEP (RM PEEP)
Intervention type(s): Procedure; Procedure
Intervention description(s): The ventilation protocol consisted of volume controlled mechanical ventilation, FiO2 0.4, inspiratory-to-expiratory (I:E) ratio at 1:2, and respiratory rate (RR) set to normocapnia (end-tidal CO2 partial pressure between 35 and 40mmHg, TV 6 mL/kg PBW and 5 cmH2O PEEP.
RMs were conducted under volume controlled ventilation with initial settings of a limit of peak inspiratory pressure at 40cmH2O, TV at 6 mL/kg PBW (PBW = 50.0+0.905*((height in cm)-152.4) for men, and = 45.5+0.905*((height in cm)-152.4) for women) Brower, et al. 1999, RR at 7 breaths/min, PEEP at5 cmH2O, and I:E ratio at1:1. The TV was then increased by steps of 4 mL/kg PBW until plateau airway pressure (Pplt) was 40 cmH2O, after which 3 breaths were allowed. Finally, the limit of peak inspiratory pressure, TV, RR, and I:E ratio were reset at values equal to those preceding the RM.; The ventilation protocol consisted of volume controlled mechanical ventilation, FiO2 0.4, in RMs was conducted under pressure controlled ventilation so ventilation technique will be changed, pressure-control mode will be started and inspiratory time is increased to 50% (inspiratory: expiratory ratio will be set to 1:1). Peak airway inspiratory pressure (Ppeak) will be initially set to 20 cmH2O for three breaths, and then PEEP will be increased in steps from 5 to10 cmH2O for five breaths, from 10 to 15 cmH2O for seven breaths, from 15 to 20 cmH2O for ten breaths while Ppeak increased to 40 cmH2O and will be maintained for three more breaths. Following ARM, volume control will be re-established using Vt 6 mL/kg and step-wise reductions in PEEP from 20 to 15 cmH2O for three breaths,and then to 5 cmH2O until the end of recruitment maneuver
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Supportive Care