Bi-PAP vs Sham Bi-PAP on Pulmonary Function in Morbidly Obese Patients After Bariatric Surgery

Not Applicable

Completed

Conditions: Pulmonary Infection
Hypoxemic Respiratory Failure
Hypoxemia
Pulmonary Disease
Atelectasis
Chronic Obstructive Pulmonary Disease (COPD)
Morbid Obesity

Brief Summary: The effect of biphasic positive airway pressure (Bi-PAP) at individualized pressures on the postoperative pulmonary recovery of morbidly obese patients (MOP) undergoing open bariatric surgery (OBS) and possible placebo device-related effects (sham-Bi-PAP) were investigated.

Detailed Description: In the present study the effect of Bi-PAP on the postoperative respiratory function and related complications of MOP undergoing OBS through a randomized sham-controlled design was investigated. Bi-PAP was applied at individualized pressures in order to optimize respiratory support and sham Bi-PAP was also used in order to neutralize possible placebo device related effect and researcher related bias.

The investigators hypothesized that the use of Bi-PAP at individualized pressures in MOP undergoing OBS, ameliorates postoperative respiratory function as well as diminishes related pulmonary complications, postoperative pain and duration of hospitalization. Primary endpoints were the difference in pre- and postoperative measurements of certain pulmonary function parameters (forced expiratory volume at one second (FEV1), forced vital capacity (FVC), peak expiratory flow rate (PEFR) and oxygen saturation by pulse oximetry (SpO2) and the incidence of certain pulmonary complications postoperatively (hypoxemia, atelectasis, lower respiratory tract infections). Secondary endpoints were postoperative pain and days of hospitalization.

Recruitment & Eligibility

Inclusion Criteria

All patients have been Morbidly Obese (BMI> 40kg/m2) for at least 10 years
All patients had unsuccessfully tried to lose weight by other non-invasive means.
All patients enrolled were continuous positive airway pressure (CPAP) and Bi-PAP naïve and had no knowledge about the Bi-PAP apparatus prior to enrollment
All patients underwent OBS (gastroplasty by Mason or gastric bypass) by the same operating team
All patients were treated with the same standard anesthetic protocol

Exclusion Criteria

Cardiovascular and pulmonary disease not related to obesity status
Chronic renal disease
Patients who were initially enrolled but did not use the allocated device (Bi-PAP or Sham Bi-PAP) for at least 12 h daily were also excluded at a later point.

Arm && Interventions

Group	Intervention	Description
Bi-PAP	Bi-PAP	Bi-PAP through nasal mask, at individualized IPAP/EPAP pressures, was applied for 3 days postoperatively. IPAP and EPAP in the Bi-PAP system were individualized for each patient in accordance with accepted values of SpO2, PaCO2, and patient synchronization and tolerability with the device.Individualized setting of pressures in patient group was applied gradually starting with 12/4 cm H2O (IPAP/EPAP) and up to 18/10 (IPAP/EPAP) with consecutive increases of 2 cm H2O.
Sham Bi-PAP	Sham Bi-PAP	Sham Bi-PAP was applied through nasal mask for 3 days postoperatively. Sham Bi-PAP was created by introducing a "hole" at the connection of the mask with the spiral tube of Bi-PAP. With this modality, also used on previous studies, the applied pressure by sham Bi-PAP was constant and equal to 2 centimeter of water (cm H2O).

Primary Outcome Measures

Name	Time	Method
Forced Expiratory Volume at One Second (FEV1) Difference	24 h before surgery and at 24, 48 and 72 h post-operatively	difference in FEV1 value measured by spirometry pre- and post-operatively
Forced Vital Capacity (FVC) Difference	24 h before surgery and at 24, 48 and 72 hours post-operatively	difference in FVC value measured by spirometry pre- and post-operatively
Peak Expiratory Flow Rate (PEFR) Difference	24 h before surgery and at 24, 48 and 72 hours post-operatively	difference in PEFR value measured by spirometry pre- and post-operatively
SpO2 Difference	24 h before surgery and at 24, 48 and 72 hours post-operatively	difference in SpO2 value measured by spirometry pre- and post-operatively
Number of Participants With Hypoxemia	At 24, 48 and 72 hours post-operatively	occurrence of hypoxemia, considered as SpO2\<90%, post-operatively
Number of Participants With Atelectasis	At 24, 48 and 72 hours post-operatively	occurrence of atelectasis as defined by chest X-ray (CXR) post-operatively with CXR before surgery as baseline

Secondary Outcome Measures

Name	Time	Method
Post-operative Pain	right before spirometry, at 24, 48 and 72 h post-operatively	Intensity of pain was assessed post-operatively by Numerical Rating Scale (NRS) (0-10, 0=no pain, 10=worst pain imaginable)
Days of Hospitalization	From day of admission to day of discharge from the hospital	duration of hospitalization, calculated by discharge date minus admission date