Intensive Alveolar Recruitment Protocol After Cardiac Surgery
Condition: Ventilator Induced Lung Injury; Cardiac Disease; Acute Lung Injury
MeSH terms: Lung Injury; Acute Lung Injury; Ventilator-Induced Lung Injury; Heart Diseases; Wounds and Injuries
Study type: Interventional

Summary: 
      The purpose of this study was to evaluate prospectively the impact of two protective
      mechanical ventilation strategies, both using low tidal volume ventilation (6 mL/kg/ibw)
      after cardiac surgery. The study selected patients presenting signals of deficient gas
      exchange (PaO2/FIO2 < 250 at a PEEP [positive end expiratory pressure] of 5 cmH2O) in the
      immediate post-operative period. An aggressive alveolar recruitment protocol applying opening
      pressures of 45 cmH2O, followed by ventilation with PEEP = 13 cmH2O, was compared to the
      standard alveolar recruitment protocol of the institution, where an opening pressure of 20
      cmH2O in the airways is followed by ventilation with PEEP = 8 cmH2O. After a stabilizing
      period of four hours of controlled mechanical ventilation, the patients followed the routine
      weaning protocol and physiotherapy protocol of the institution.
    

Detailed description: 
      The postoperative period of cardiac surgery is associated with the development of pulmonary
      complications. Functional residual capacity can be reduced up to 50% and pulmonary volumes
      may be decreased until three months after surgery.

      Lung injury is the result of pulmonary inflammation (activated by cardiopulmonary bypass, the
      surgical procedure itself and ischemia-reperfusion injury), the adopted mechanical
      ventilation strategy and a consequence of previous cardiac and/or pulmonary dysfunction.

      The use of protective mechanical ventilation strategies with low tidal volumes since the
      immediate postoperative period, or since the operating room, has been shown to attenuate and
      prevent lung injury in previous studies selecting with high-risk patients.

      A more complex topic, however, has been the proof of the additional benefit of alveolar
      recruitment maneuvers during the brief period of mechanical ventilation after surgery. While
      the experimental evidence suggests that the use of an open lung approach could minimize the
      shearing forces in the lung parenchyma, enhancing the protection afforded by low tidal volume
      ventilation, innumerous concerns about the hemodynamic side effects, and the possibility of
      barotrauma have prevented the routine use of intensive alveolar recruitment protocols.
      Another matter of concern is the net efficacy of a recruitment maneuver applied in the
      post-operative period, instead of the intra-operative period.

      Thus, this study compared the impact of two protective mechanical ventilation strategies,
      both using low-tidal volume ventilation (6 mL/kg/ibw) after cardiac surgery, in a selective
      population of patients presenting signals of deficient gas exchange (PaO2/FIO2 < 250 at a
      PEEP of 5 cmH2O) in the immediate post-operative period. In a previous study at this
      institution, this subgroup of patients was shown to be at higher risks of postoperative
      pulmonary complications.

      During the short period of controlled mechanical ventilation after the patient arrival from
      the operating theater, an aggressive alveolar recruitment protocol applying opening pressures
      of 45 cmH2O, followed by ventilation with PEEP = 13 cmH2O, was compared to the standard
      alveolar recruitment protocol of the institution, where an opening pressure of 20 cmH2O in
      the airways is followed by ventilation with PEEP = 8 cmH2O. After an stabilizing period of
      four hours of controlled mechanical ventilation, the patients followed the routine weaning
      protocol and physiotherapy protocol of the institution.

      Our hypothesis was that the aggressive alveolar recruitment strategy might help in the
      reversal of collapse created during the surgery and short term mechanical ventilation during
      anesthesia and patient transportation. Previous studies have shown that this effect may
      extend to the post-extubation period, impairing lung function for a few days.

      Thus, we tested if the effect of an aggressive alveolar recruitment protocol was translated
      in a better lung compliance, better gas exchange, and fewer pulmonary complications in the
      post-operative periods (this latter was our primary outcome). Analysis of the length of stay
      was also scrutinized, consisting in our secondary outcome. All hemodynamic complications was
      reported, since we also anticipated that events of hemodynamic impairment might be more
      frequent in the aggressive recruitment arm, eventually obscuring the expected benefits .
    

Intervention name(s): Intensive Alveolar Recruitment; Moderate Alveolar Recruitment
Intervention type(s): Other; Other
Intervention description(s): Recruitment with opening pressures of 45 cmH2O in the airways, followed by ventilation with PEEP = 13 cmH2O, during 4 hours of protective mechanical ventilation with tidal volume (VT) = 6 mL/kg/pbw.; Recruitment with opening pressures of 20 cmH2O in the airways, followed by ventilation with PEEP = 8 cmH2O, during 4 hours of protective mechanical ventilation with VT = 6 mL/kg/pbw.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Mechanical ventilation; Open lung approach; Blood gases; Cardiac surgery; Pulmonary complications