The Effects of Hyperventilation Prior to CO2 Insufflation During Laparoscopic Cholecystectomy
Condition: Laparoscopic Cholecystectomy
MeSH terms: Hyperventilation
Study type: Interventional
Phase: Phase 1

Summary: 
      The investigators postulated that the use of hyperventilation after induction of anesthesia
      before CO2 insufflation for laparoscopic surgery in Trendelenburg position would maintain
      normocapnia and reduce the hemodynamic percussion response of CO2 insufflation.
    

Detailed description: 
      The use of laparoscopic techniques has become common in clinical practice. Absorption of
      carbon dioxide (CO2) from the peritoneal cavity is the potential mechanism for hypercapnia
      and a rise in the end-tidal carbon dioxide (EtCO2). Mild hypercarbia causes sympathetic
      stimulation which results in a fivefold increase in arginine vasopressin (AVP), tachycardia,
      increased systemic vascular resistance, systemic arterial pressure, central venous pressure
      and cardiac output.1 Severe hypercarbia exerts a negative inotropic effect on the heart and
      reduces left ventricular function.2 Hemodynamic alterations occur only when the PaCO2 is
      increased by 30 per cent above the normal levels.

      Clearance of CO2 is a function of the adequacy of alveolar ventilation with respect to
      pulmonary perfusion. Controlled hyperventilation has proved to be superior over spontaneous
      respiration or controlled normo-ventilation for maintaining normal PCO2 during laparoscopy.
      During pelvic laparoscopy there was a rapid rise of about 30% in the CO2 load eliminated by
      the lungs. This quickly reached a plateau and could be compensated by hyperventilation of the
      lungs with a 30% increase in minute ventilation.

      Papadimitriou and co' workers concluded that under sevoflurane anesthesia MAC, prophylactic
      hyperventilation to ensure mild hypocapnia, (around 33 mmHg) limits the cerebral blood flow
      velocities enhancing effect of CO2 insufflation, compared with permissive hypercapnia (up to
      45 mmHg), during gynecological laparoscopies. However, others advocated that hyperventilation
      and the head-up position before CO2 insufflation are not sufficient to prevent the
      CO2-mediated cerebral hemodynamic effects of low-pressure pneumoperitoneum (5-8 mmHg) in
      children, underwent laparoscopic fundoplication.
    

Intervention name(s): Ventilation
Intervention type(s): Procedure
Intervention description(s): Mechanical ventilation was conducted in all the patients with a Datex-Ohmeda Aestiva/5 Smart Ventilator (Madison, WI) through a rebreathing circuit incorporating a CO2 absorber, a heat and moisture exchanger using volume-controlled mode with an inspiratory to expiratory ratio of 1:2.5, and positive end-expiratory pressure (PEEP) of 5 cm H2O. Plateau pressure was kept as low as possible with an upper limit of 30 cm H2O, and the absence of auto-PEEP was ensured by a drop of the expiratory flow to zero on the flow-time curve.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Anaesthesia; laparoscopic cholecystectomy; CO2 insufflation; hemodynamic; hyperventilation