Clinical trial NCT03975348: Ventilation Distribution After Bariatric Surgery
Official title: Evaluation of Ventilation Distribution After Bariatric Surgery - High Flow Nasal Cannulas Versus Continuous Positive Airway Pressure
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Bariatric Surgery Candidate
Atelectasis, Postoperative Pulmonary
Keywords: High flow nasal cannula
Bariatric surgery
Postoperative atelectasis
Electrical impedance tomography
Lead sponsor: University of Trieste
Sponsor class: OTHER
First posted: 2019-06-05
Enrollment: 15
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NON_RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: Obese patients have an increased risk of developing post-operative respiratory complications due to their comorbidities. They have a restrictive ventilatory defect with reduction of lung volumes and expiratory flow limitation, higher airway resistance and collapsibility of the upper respiratory tract. These abnormalities are worsened by general anesthesia and opioid administration. It has been proved that oxygen therapy with HFNC (high flow nasal cannula) increases lung volumes through a continuous positive airway pressure (CPAP)-effect. This also improves gas exchange and decreases anatomical dead space. At the present time, CPAP represents the gold standard for the prevention of postoperative pulmonary complications. The purpose of this study is to evaluate lung ventilation, gas exchange and comfort with HFNC compared with CPAP during the post-operative period in patients who undergo laparoscopic bariatric surgery.

Detailed description: Immediately after bariatric surgery, patients will follow a pre-determined schedule of oxygen therapy with conventional facemask (from the beginning to minute 10), HFNC (with a flow of 40 L/min from minute 11 to 20, 60 L/min from minute 21to 30, 80 L/min from minute 31 to 40, 100 L/min from minute 41 to 50, 80 L/min from minute 51 to 60, 60 L/min from minute 61 to 70, 40 L/min from minute 71 to 80), conventional facemask again (washout, from minute 81 to 90) and CPAP (10 cmH2O, from minute 91 to 100). Lung ventilation will be evaluated with electrical impedance tomography (EIT), which measures thoracic impedance variations related to changes in lung aeration. At the end of each 10 minutes-period the following data will be collected: electrical impedance tomography data (to calculate the global inhomogeneity index, Δ end-expiratory lung impedance and tidal impedance variation), hemodynamic parameters, respiratory rate, SpO2, pain (numerical rating scale), level of sedation (Ramsey score) and patient comfort (modified Borg scale). An arterial blood gas will be collected at the end of the following steps: baseline facemask, HFNC 40 and 100 L/min, washout facemask and CPAP. Data about anesthetic/analgesic drugs and ventilation parameters will also be collected.

Eligibility criteria: Inclusion Criteria:

* Patient's consent to the trial
* Candidate to laparoscopic bariatric surgery (sleeve gastrectomy or Roux-en-Y gastric bypass)
* BMI 35-50 kg/m2
* ASA class 1-3

Exclusion Criteria:

* Obesity hypoventilation syndrome
* Contraindication to EIT (e.g. implantable cardioverter-defibrillator)

Primary outcomes:
measure: Change of global inhomogeneity index
timeFrame: The data needed to calculate the index will be collected at minute 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 (i.e. at the end of every step of oxygen therapy). The values obtained will then all be compared each other.
Secondary outcomes:
measure: Change of Δ end expiratory lung impedance (ΔEELI)
timeFrame: The data will be collected at minute 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 (i.e. at the end of every step of oxygen therapy). The values obtained will then all be compared each other.
measure: Change of tidal impedance variation
timeFrame: The data will be collected at minute 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 (i.e. at the end of every step of oxygen therapy). The values obtained will then all be compared each other.
measure: Change of oxygenation
timeFrame: The blood gas analysis will be performed at minute 10, 20, 50, 90 and 100. The values will then all be compared each other.
measure: Change of carbon dioxide
timeFrame: The blood gas analysis will be performed at minute 10, 20, 50, 90 and 100. The values will then all be compared each other.
measure: Change of pH
timeFrame: The blood gas analysis will be performed at minute 10, 20, 50, 90 and 100. The values will then all be compared each other.
measure: Change of respiratory rate
timeFrame: The parameter will be collected at minute 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 (i.e. at the end of every step of oxygen therapy). The values obtained will then all be compared each other.
measure: Change of patient's comfort: modified Borg dyspnea scale
timeFrame: The parameter will be collected at minute 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 (i.e. at the end of every step of oxygen therapy). The values obtained will then all be compared each other.
Other outcomes:
Locations:
city: Trieste
country: Italy
facility: Azienda Sanitaria Universitaria Integrata di Trieste
Study officials:
affiliation: Azienda Sanitaria Universitaria Integrata di Trieste
name: Lucia Comuzzi
role: PRINCIPAL_INVESTIGATOR
References: