Skip to main content
OpenTrials
Completed

NCT Number: NCT03975348

Ventilation Distribution After Bariatric Surgery

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.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Bariatric Surgery Candidate Atelectasis, Postoperative Pulmonary Lung Diseases Pulmonary Atelectasis Respiratory Tract Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Azienda Sanitaria Universitaria Integrata di Trieste

Trieste, 34100, Italy

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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)

Treatment and study plan

High Flow Nasal Cannula

Device

High flow of warm and humidified oxygen/air mixture delivered through nasal cannula

Continuous Positive Airway Pressure

Device

Positive airway pressure applied through a sealed face mask

Facemask

Device

Oxygen therapy through a conventional facemask

Primary outcomes

  1. Change of global inhomogeneity index

    Time frame: 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.

    This parameter, calculated from data collected with EIT, evaluates lung ventilation distribution. To calculate this index, the median value of regional impedance changes from ventilated regions within the tidal image has to be computed, then the sum of differences between the median and every pixel value needs to be calculated, and the result must be normalised by the sum of impedance values within the lung area. The minimum value of the index is 0 and corresponds to homogeneous ventilation, whereas the maximum value is 1 and corresponds to inhomogeneous ventilation (in this context likely due to atelectasis).

Secondary outcomes

  1. Change of Δ end expiratory lung impedance (ΔEELI)

    Time frame: 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.

    The parameter, measured with EIT, expresses deviations of the regional end-expiratory lung impedance in relation to the global tidal impedance variation. ΔEELI closely correlates with changes of end-expiratory lung volume of the EIT sensitivity region.

  2. Change of tidal impedance variation

    Time frame: 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.

    This parameter, measured with EIT, corresponds to the difference between end-expiratory and end-inspiratory lung impedance and is related to tidal volume. It will be expressed in units, where one unit corresponds to the tidal impedance variation of the patient breathing with baseline conventional facemask.

  3. Change of oxygenation

    Time frame: The blood gas analysis will be performed at minute 10, 20, 50, 90 and 100. The values will then all be compared each other.

    Oxygen arterial partial pressure

  4. Change of carbon dioxide

    Time frame: The blood gas analysis will be performed at minute 10, 20, 50, 90 and 100. The values will then all be compared each other.

    Carbon dioxide arterial partial pressure

  5. Change of pH

    Time frame: The blood gas analysis will be performed at minute 10, 20, 50, 90 and 100. The values will then all be compared each other.

    Arterial pH

  6. Change of respiratory rate

    Time frame: 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.

    Respiratory rate

  7. Change of patient's comfort: modified Borg dyspnea scale

    Time frame: 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.

    Comfort related to the oxygen therapy will be evaluated with the modified Borg dyspnea scale (0: nothing at all, 0.5: very, very slight, 1: very slight, 2: slight, 3: moderate, 4: somewhat severe, 5: severe, 6, 7: very severe, 8, 9: very, very severe - almost maximal, 10: maximal)

Sponsors and collaborators

Lead sponsor

University of Trieste

Other

Registry information

Official study title

Evaluation of Ventilation Distribution After Bariatric Surgery - High Flow Nasal Cannulas Versus Continuous Positive Airway Pressure

Important dates

Study start
2019
Primary completion
2019
Study completion
2019
First posted
Jun 5, 2019
Registry last updated
Jul 30, 2020

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.