Prophylactic Use of Noninvasive Ventilation in the Postoperative Period of Bariatric Surgery
Condition: Bariatric Surgery Candidate; Obesity, Morbid; Ventilatory Failure
MeSH terms: Hypoventilation; Obesity, Morbid
Study type: Interventional

Summary: 
      Comorbidities associated with severe obesity determine an important public health problem.
      Few methods are considered potentially effective for the treatment of severe obesity and the
      clinical relevance of bariatric surgery is growing, as well as the number of procedures
      performed. The insertion of the physiotherapist in the multiprofessional team responsible for
      performing the surgical procedure is essential from the preoperative screening and evaluation
      to the prevention and treatment of postoperative complications. Therefore, the
      physiopathological aspects involved with severe obesity, the technical aspects and risks of
      the surgical procedure, as well as the physiotherapeutic techniques that have scientific
      proof must be known by the physiotherapist responsible for the surgical follow-up of the
      patient. In this context, the use of non-invasive ventilation (NIV) in the postoperative
      period of bariatric surgery has ample therapeutic potential. The present research project
      aims to evaluate the immediate prophylactic use of NIV on the respiratory and functional
      recovery of the patients.
    

Detailed description: 
      The study will be performed at the surgical center of the Hospital de Clínicas of Porto
      Alegre. After approval by the Research Ethics Committee, patients must sign the Term of
      Consent for inclusion in the study. A blinded investigator will record clinical,
      anthropometric, pulmonary function tests, and functional measures. Patients submitted to open
      bariatric surgery will be divided into two groups for the use of NIV: immediate
      post-extubation (IG) and non-intervention (standard group [GP]). Patients will be randomly
      assigned to the groups. All subjects will undergo general anesthesia and postoperative
      analgesia, using a standardized surgical team approach. Patients who present the
      contraindication criteria for the use of NIV will be excluded from the study.

      After the surgical procedure and extubation, GP subjects will receive oxygen therapy through
      a nasal cannula with 4 to 6 L / min of oxygen according to the team routine and patient need.
      The subjects in the immediate intervention group (GI) will be extubated and placed in NIV the
      moment they enter the recovery room through a portable ventilator (Esprit ® or BiPAP Vision
      ®, Respironics) in face mask. The parameters will be adjusted as follows: FiO2 = 50%,
      positive expiratory pressure (EPAP, starting at 4-6 cmH2O and adjusting 1-2 cmH2O to avoid
      snoring, apnea, paradoxical breathing and desaturations) and adjusted inspiratory positive
      pressure (IPAP) to maintain a tidal volume of 400 to 500 ml, maintaining IPAP <15cmH2O17.
      Individuals will receive this ventilatory support for 1 hour. After this period the patients
      will be submitted to the same care of GP patients. Measurement of respiratory muscle strength
      and lung function will be recorded in Time 1 (in the preoperative period), Time 2 (at the
      time of entry of the recovery room) and Time 3 (1 hour after extubation, with withdrawal of
      the support ventilatory). Vital signs (heart rate, peripheral O2 Saturation and Blood
      Pressure) will also be recorded through the multi-parameter monitor (IntelliVue MP40).

      The functional evaluation will be performed in the period of the initial data collection
      through the Functional Status Score for the ICU (FSS-ICU) and Functional Independence Measure
      (MIF). Patients will be monitored during the hospitalization period until hospital discharge
      and records of postoperative complications (radiological changes, infections and surgical
      anastomosis fistulas) will be recorded by blinded evaluator. The final evaluation will be
      done through the MIF, through telephone contact 1 month after the surgery.

      During the study participation patients may present with discomfort, nausea, vomiting and /
      or pain related to the use of non-invasive ventilation and procedures performed to evaluate
      muscle strength, lung function and functionality. In a study with methodology and similar
      population, such risks / complications were not reported16, however, if they occur, the
      procedures will be immediately interrupted and patients will be assisted by the study
      researchers in order to preserve the patients and the reliability of the results.
    

Intervention name(s): Non invasive mechanical ventilation; GP
Intervention type(s): Device; Device
Intervention description(s): Prophylactic non invasive mechanical ventilation; GP subjects will receive oxygen therapy through a nasal cannula with 4 to 6 L / min of oxygen according to team routine and patient need.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Prevention