Extubation With or Without Spontaneous Breathing Trial
Condition: Respiratory Failure
MeSH terms: Respiratory Insufficiency
Study type: Interventional

Summary: 
      Spontaneous breathing trial (SBT) has long been thought to be a essential process before
      extubation. In this study,the investigator hypothesized that SBT could be not essential
      during weaning from ventilator and investigated whether weaning could be better done without
      a spontaneous breathing trial in non-COPD（COPD, Chronic Obstructive Pulmonary Disease）
      critically ill patients. This study has revealed, for the first time, that compared with use
      of SBT in discontinuing ventilator process, patients underwent successful extubation without
      SBT. For this subset of patients the findings suggest that SBT may be excluded preceding
      extubation in a general intensive care population.
    

Detailed description: 
      In this 1000-bed primary teaching hospital, the study was conducted in the 8-bed adult
      general ICU over the course of 13 months. All patients enrolled in this study were
      mechanically ventilated for more than 48 hrs via endotracheal tubes during the study period.
      The investigation was approved by the hospital ethics committee, and informed written consent
      was obtained from the next of kin of every patient. Patients were ventilated in pressure
      support (PS) during the entire weaning period. The levels of inspiratory PS and positive
      end-expiratory pressure （PEEP) were progressively reduced depending on the patient's clinical
      assessment and blood gas values. Patients enrolled in this study had to meet all of the
      following readiness criteria: show significant improvement or resolution of the underlying
      cause of acute respiratory failure; be fully awake; require bronchial toilet less than twice
      in the 4 hours proceeding the assessment; stable hemodynamics without further need of
      vasoactive agents; arterial oxygen tension (PaO2)/fraction of inspired oxygen (FiO2) ratio
      >200 at a PEEP of 4.0 cm H2O with a maximal FiO2 of 0.40; core temperature <38.0℃; systolic
      blood pressure >90 mmHg; respiratory rate to tidal volume ratio (RVR) <105 breaths/min/L. The
      RVR was calculated after 1 min of spontaneous breathing.The maximal inspiratory PS of 12 cm
      H2O and no mandatory machine breaths supplied from the ventilator.

      Study protocol The investigators investigated the weaning process with and without SBT. All
      patients were continuously assessed according to the readiness criteria and were screened for
      enrollment once a day. As soon as the patient was ready for weaning, he or she was randomly
      assigned to SBT or no-SBT study groups. Randomization was carried out in a blinded fashion
      using opaque and sealed envelopes. All patients in the study breathed through the ventilator
      circuit with flow-triggering (2L/min) and pressure support ventilation mode. In the SBT
      group, the patients underwent a 1 hr SBT with inspiratory PS of 7 cmH2O with other settings
      remaining constant (FiO2, PEEP, trigger sensitivity). For patients showing poor tolerance to
      the SBT, full ventilation support was immediately recommenced. This was defined by the
      following failure criteria: a decrease in oxygen saturation to <90%; respiratory rate >35/min
      for more than 5 min, in the presence of diaphoresis or thoraco-abdominal paradox; sustained
      increase in heart rate (>140/min), or significant change in systolic blood pressure (>180 or
      <90 mmHg). The patients who tolerated the SBT underwent immediate extubation and received
      (breathed in) supplemental oxygen via a facemask. In no-SBT group, as soon as a patient met
      readiness criteria, he or she underwent extubation without SBT process and received
      supplemental oxygen via a facemask. Following extubation, noninvasive ventilatory support was
      introduced in the following circumstances: hypoxemia (SaO2<90% for >15mins) under receiving
      supplemental oxygen; presence of respiratory acidosis (arterial PH<7.35 with arterial carbon
      dioxide tension (PaCO2)>45mmHg; and respiratory rate >25 breaths/min for 1 hr. The mode of
      ventilation was Bi-level Positive Airway Pressure (BiPAP). When such support was deemed
      inadequate (hypoxemia, hypercapnea, or respiratory distress), the patient was reintubated and
      mechanically ventilated.

      The SBT and extubation were performed by two doctors who are members of the research team.
      Decisions regarding reintubation were made by doctors who were blinded for the treatment
      group. Extubation failure is defined as reintubation within 48 hrs. The reasons for
      reintubation were prospectively recorded.

      Statistical Analysis Results are expressed as mean ± SD. Mean values of selected demographic
      variables and physiologic parameters of patients who underwent SBT were compared by student's
      t tests to those who underwent extubation directly. The differences in proportions between
      the two groups were determined using chi square test (X2-test).
    

Intervention name(s): spontaneous breathing trial
Intervention type(s): Behavioral
Allocation: Randomized
Intervention model: Parallel Assignment
Primary purpose: Treatment
Keywords: extubation,Respiration, Artificial