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NCT Number: NCT02579798

Does Pulmonary Compliance Optimization Through PEEP Manipulations Reduces the Incidence of Postoperative Hypoxaemia in Bariatric Surgery?

General anesthesia, even in patients in good health, impairs gas exchanges and ventilatory mechanics. These effects result primarily from atelectasis formation. They occur in 85-90% of healthy patients in the minutes following the induction when a positive end expiratory pressure (PEEP) is not used.

The functional residual capacity (FRC) of obese patients during general anesthesia is even smaller than the one of healthy patients. There is a direct relationship between the body mass index and the decrease of the functional residual capacity. Obese patients have therefore more atelectasis. The increased abdominal pressure during the pneumoperitoneum will increase the decrease of the CRF, and thus aggravate the formation of these atelectasis.

Atelectasis affect the peroperative gas exchanges and are likely to be involved in the worsening of postoperative hypoxemia episodes. In addition, atelectasis alter the clearance of secretions and the lymph flow, which predispose to lung infections.Taking all these factors into account, it is logical to think that the atelectasis presence can lead to an increase of the postsurgical morbidity (respiratory distress, infections). That is why actively fighting against the formation of these atelectasis is important.

There is a lack of scientific evidence to say that the strategies against atelectasis as PEEP have a significant impact on the patient's postoperative status. The expected clinical benefits balance (reduction of respiratory distress episodes, infections and mortality) versus the risks linked to the maneuvers done to reduce the development of atelectasis (barotraumas, cardiac complications) remains to be determined.

The primary goal of this study is to evaluate the impact of two different alveolar recruitment strategies on the incidence of postoperative hypoxemia in obese patients after bariatric surgery.

The secondary objectives of this study are to compare the number of recruitment maneuvers, the Pa02 / FI02 ratio (ratio of arterial oxygen partial pressure to fractional inspired oxygen), the dynamic compliance, the anatomic dead space and intraoperative PaCO2-EtCO2 gradient (arterial and end tidal gradient) between two alveolar recruitment strategies applied in obese patients during laparoscopic bariatric surgery (gastric bypass or sleeve gastrectomy).

The tertiary objectives of this study are to report the number of respiratory complications and postoperative wound infections at the 30th postoperative day.

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Key information

Conditions

Bariatric Surgery Body Weight Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

CHU Brugmann

Brussels, 1020, Belgium

About this study

General anesthesia, even in patients in good health, impairs gas exchanges and ventilatory mechanics. These effects result primarily from atelectasis formation. They occur in 85-90% of healthy patients in the minutes following the induction when a positive end expiratory pressure (PEEP) is not used.

These atelectasis are formed on one hand by the reduction of the functional residual capacity (FRC) following a compression mechanism (loss of the inspiratory muscle tone, which is accompanied by a chest wall configuration change and a diaphragm cephalic movement) and on the other hand by a denitrogenation absorption process (ventilation at high Fi02 (oxygen inspired fraction) causing complete absorption of O2 with lack of support for the alveolus, which then collapses).

The FRC of obese patients during general anesthesia is even smaller than the one of healthy patients. There is a direct relationship between the body mass index and the decrease of the functional residual capacity. Obese patients have therefore more atelectasis. The increased abdominal pressure during the pneumoperitoneum will increase the decrease of the CRF, and thus aggravate the formation of these atelectasis.

Atelectasis affect the peroperative gas exchanges and are likely to be involved in the worsening of postoperative hypoxemia episodes. In addition, atelectasis alter the clearance of secretions and the lymph flow, which predispose to lung infections.Taking all these factors into account, it is logical to think that the atelectasis presence can lead to an increase of the postsurgical morbidity (respiratory distress, infections). That is why actively fighting against the formation of these atelectasis is important.

Several strategies have been studied in order to improve respiratory mechanics and reduce impaired gas exchange during laparoscopic surgery in obese patients. The position called "chair", mechanical ventilation with PEEP, recruitment maneuvers followed by the PEEP, and spontaneous ventilation with CPAP before extubation, are all strategies that have proven effective to decrease development these atelectasis.

Currently, the scientific community agrees on the fact that PEEP improves intraoperative respiratory function (improved compliance, oxygenation) especially in conjunction with recruitment maneuvers.

But there is a lack of scientific evidence to say that the strategies against atelectasis as PEEP have a significant impact on the patient's postoperative status. The expected clinical benefits balance (reduction of respiratory distress episodes, infections and mortality) versus the risks linked to the maneuvers done to reduce the development of atelectasis (barotraumas, cardiac complications) remains to be determined.

The primary goal of this study is to evaluate the impact of two different alveolar recruitment strategies on the incidence of postoperative hypoxemia in obese patients after bariatric surgery.

The secondary objectives of this study are to compare the number of recruitment maneuvers, the Pa02 / FI02 ratio, the dynamic compliance, the anatomic dead space and intraoperative PaCO2-EtCO2 gradient between two alveolar recruitment strategies applied in obese patients during laparoscopic bariatric surgery (gastric bypass or sleeve gastrectomy).

The tertiary objectives of this study are to report the number of respiratory complications and postoperative wound infections at the 30th postoperative day.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • ASA score (American Society of Anesthesiologists ) of II or III
  • BMI > 35 kg/m²
  • Elective laparoscopic bariatric surgery: gastric bypass or sleeve

Exclusion criteria

  • Restrictive (CPT <65%) or obstructive (VEMS/CV < 69%) chronic lung disease
  • Increase of the intracranial pressure
  • History of smoking with chronic obstructive disease (VEMS/CV)
  • Active tabagism
  • Ongoing pregnancy
  • History of heart failure (NYHA III or IV) or coronary artery disease
  • Urgent surgery
  • Allergy to a drug used within the study
  • Lack of written informed consent

Treatment and study plan

PEEP (positive end-expiratory pressure)

Device

Primary outcomes

  1. Number of hypoxemia episodes (Sp02<90%)

    Time frame: continuously during 48h after surgery

    This will be monitored by a portable saturometer (OxyTrue A, Bluepoint, Germany). This saturometer will allow the investigators to count the number of hypoxemia episodes (Sp02<90%) and their duration in obese patients, in the postoperative period.

  2. Number of hypoxemia episodes (Sp02<95%)

    Time frame: continuously during 48h after surgery

    This will be monitored by a portable saturometer (OxyTrue A, Bluepoint, Germany). This saturometer will allow the investigators to count the number of hypoxemia episodes (Sp02<95%) and their duration in obese patients, in the postoperative period.

Secondary outcomes

  1. Number of recruitment manoeuvers

    Time frame: From the beginning of the surgery till moment 1 (after induction/intubation, patient laying flat, without pneumoperitoneum)

    Recruitment manoeuver are performed if patient saturation drops below 95%.

  2. Number of recruitment manoeuvers

    Time frame: From moment 1 till moment 2 (after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation)

    Recruitment manoeuver are performed if patient saturation drops below 95%.

  3. Number of recruitment manoeuvers

    Time frame: From moment 2 till moment 3 (after pneumoperitoneum exsufflation - patient lying flat)

    Recruitment manoeuver are performed if patient saturation drops below 95%.

  4. Number of recruitment manoeuvers

    Time frame: From moment 3 till the end of the surgery (patient leaving the theater)

    Recruitment manoeuver are performed if patient saturation drops below 95%.

  5. Pulmonary dynamic compliance (Cd) - preoperative

    Time frame: Just before surgery, at ambient air contact

    This will be determined by the following formula: Cd = Vt/P(peak)-PEEP and expressed in mL/cmH2O

  6. Pulmonary dynamic compliance (Cd) - moment 1

    Time frame: just after the anesthesia induction/intubation, patient laying flat, without pneumoperitory

    This will be determined by the following formula: Cd = Vt/P(peak)-PEEP and expressed in mL/cmH2O

  7. Pulmonary dynamic compliance (Cd) -moment 2

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    This will be determined by the following formula: Cd = Vt/P(peak)-PEEP and expressed in mL/cmH2O

  8. Pulmonary dynamic compliance (Cd) -moment 3

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    This will be determined by the following formula: Cd = Vt/P(peak)-PEEP and expressed in mL/cmH2O

  9. Pulmonary dynamic compliance (Cd) -if recruitment manoeuvers

    Time frame: Five minutes after any recruitment manoeuver

    This will be determined by the following formula: Cd = Vt/P(peak)-PEEP and expressed in mL/cmH2O

  10. Anatomic dead space - preoperative

    Time frame: Just before surgery, at ambient air contact

    This will be determined by this formula: VD = VT (1-PEtCO2/PaC02)

  11. Anatomic dead space -moment 1

    Time frame: just after the anesthesia induction/intubation, patient laying flat, without pneumoperitory

    This will be determined by this formula: VD = VT (1-PEtCO2/PaC02)

  12. Anatomic dead space -moment 2

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    This will be determined by this formula: VD = VT (1-PEtCO2/PaC02)

  13. Anatomic dead space -moment 3

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    This will be determined by this formula: VD = VT (1-PEtCO2/PaC02)

  14. Anatomic dead space -if recruitment manoeuvers

    Time frame: Five minutes after any recruitment manoeuver

    This will be determined by this formula: VD = VT (1-PEtCO2/PaC02)

  15. PaO2/FiO2 ratio - preoperative

    Time frame: Just before surgery, at ambient air contact

    Arterial oxygen partial pressure to fractional inspired oxygen ratio

  16. PaO2/FiO2 ratio - moment 1

    Time frame: just after the anesthesia induction/intubation, patient laying flat, without pneumoperitory

    Arterial oxygen partial pressure to fractional inspired oxygen ratio

  17. PaO2/FiO2 ratio - moment 2

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    Arterial oxygen partial pressure to fractional inspired oxygen ratio

  18. PaO2/FiO2 ratio - moment 3

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    Arterial oxygen partial pressure to fractional inspired oxygen ratio

  19. PaO2/FiO2 ratio - if recruitment manoeuvers

    Time frame: Five minutes after any recruitment manoeuver

    Arterial oxygen partial pressure to fractional inspired oxygen ratio

  20. PaCO2-EtCO2 gradient - preoperative

    Time frame: Just before surgery, at ambient air contact

    The gradient between the partial pressure of carbon dioxide in the arterial blood (PaCO2) and the CO2 end-tidal partial pressure (EtCO2) is used to evaluate the effectiveness of alveolar recruitment.

  21. PaCO2-EtCO2 gradient - moment 1

    Time frame: just after the anesthesia induction/intubation, patient laying flat, without pneumoperitory

    The gradient between the partial pressure of carbon dioxide in the arterial blood (PaCO2) and the CO2 end-tidal partial pressure (EtCO2) is used to evaluate the effectiveness of alveolar recruitment.

  22. PaCO2-EtCO2 gradient - moment 2

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    The gradient between the partial pressure of carbon dioxide in the arterial blood (PaCO2) and the CO2 end-tidal partial pressure (EtCO2) is used to evaluate the effectiveness of alveolar recruitment.

  23. PaCO2-EtCO2 gradient - moment 3

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    The gradient between the partial pressure of carbon dioxide in the arterial blood (PaCO2) and the CO2 end-tidal partial pressure (EtCO2) is used to evaluate the effectiveness of alveolar recruitment.

  24. PaCO2-EtCO2 gradient - if recruitment manoeuvers

    Time frame: Five minutes after any recruitment manoeuver

    The gradient between the partial pressure of carbon dioxide in the arterial blood (PaCO2) and the CO2 end-tidal partial pressure (EtCO2) is used to evaluate the effectiveness of alveolar recruitment.

  25. Number of respiratory complications

    Time frame: 30 days after surgery

    Number of hospitalisations due to respiratory complications within 30 days after surgery.

  26. Number of postoperative wound infections

    Time frame: 30 days after surgery

    All patients are seen at the surgical consultation on day 30 after surgery. The anamnesis performed during that consultation enables the investigators to identify patients with wound infections (defined as a need for local or oral antibiotics, additional hospitalisation or abnormal cicatrisation).

  27. Pre-operative physiologic measures: cardiac frequency (FC)

    Time frame: Just before surgery, at ambient air contact

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  28. Pre-operative physiologic measures: Arterial tension (TA)

    Time frame: Just before surgery, at ambient air contact

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  29. Pre-operative physiologic measures: pH

    Time frame: Just before surgery, at ambient air contact

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  30. Pre-operative physiologic measures: partial pressure of carbon dioxide in the arterial blood (PaCO2)

    Time frame: Just before surgery, at ambient air contact

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens).

  31. Operative physiologic measures - moment 1: FC

    Time frame: just after induction/intubation, patient laying flat, without pneumoperitoneum

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  32. Operative physiologic measures - moment 1: PAM (Average arterial pressure)

    Time frame: just after induction/intubation, patient laying flat, without pneumoperitoneum

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  33. Operative physiologic measures - moment 1: pH

    Time frame: just after induction/intubation, patient laying flat, without pneumoperitoneum

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  34. Operative physiologic measures - moment 1: PaCO2

    Time frame: just after induction/intubation, patient laying flat, without pneumoperitoneum

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  35. Operative physiologic measures - moment 1: CO2

    Time frame: just after induction/intubation, patient laying flat, without pneumoperitoneum

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  36. Operative physiologic measures - moment 2: FC

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  37. Operative physiologic measures - moment 2: PAM

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  38. Operative physiologic measures - moment 2: pH

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  39. Operative physiologic measures - moment 2: PaCO2

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  40. Operative physiologic measures - moment 2: CO2

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  41. Operative physiologic measures - moment 3: FC

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  42. Operative physiologic measures - moment 3: PAM

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  43. Operative physiologic measures - moment 3: pH

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  44. Operative physiologic measures - moment 3: CO2

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  45. Operative physiologic measures - moment 3: PaCO2

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  46. Operative physiologic measures - if recruitment manoeuvers occurs: FC

    Time frame: Five minutes after any recruitment manoeuver

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  47. Operative physiologic measures - if recruitment manoeuvers occurs: PAM

    Time frame: Five minutes after any recruitment manoeuver

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  48. Operative physiologic measures - if recruitment manoeuvers occurs: SpO2

    Time frame: Five minutes after any recruitment manoeuver

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  49. Operative physiologic measures - if recruitment manoeuvers occurs: pH

    Time frame: Five minutes after any recruitment manoeuver

    The hemodynamic and respiratory parameters of the patient are measured by means of a Datex-Ohmeda Acertys machine (Aisys type).

  50. Operative physiologic measures - if recruitment manoeuvers occurs: PaCO2

    Time frame: Five minutes after any recruitment manoeuver

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  51. Operative physiologic measures - if recruitment manoeuvers occurs: PaO2

    Time frame: Five minutes after any recruitment manoeuver

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  52. Operative physiologic measures - if recruitment manoeuvers occurs: CO2

    Time frame: Five minutes after any recruitment manoeuver

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  53. Pre-operative physiologic measures: partial pressure of oxygen in the arterial blood (PaO2)

    Time frame: Just before surgery, at ambient air contact

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  54. Operative physiologic measures - moment 1: PaO2

    Time frame: just after induction/intubation, patient laying flat, without pneumoperitoneum

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  55. Operative physiologic measures - moment 2: PaO2

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  56. Operative physiologic measures - moment 3: PaO2

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  57. Pre-operative physiologic measures: Oxygen Pulsated Saturation (SpO2)

    Time frame: Just before surgery, at ambient air contact

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  58. Operative physiologic measures - moment 1: SpO2

    Time frame: just after induction/intubation, patient laying flat, without pneumoperitoneum

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  59. Operative physiologic measures - moment 2: SpO2

    Time frame: just after peritoneal insufflation and anti-trendenlenbourg (anti-trent) implementation

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

  60. Operative physiologic measures - moment 3: SpO2

    Time frame: just after pneumoperitoneum exsufflation - patient lying flat

    The gasometric parameters of the patient are analyzed with a Rapidlab 1265 machine (Siemens)

Sponsors and collaborators

Lead sponsor

Brugmann University Hospital

Other

Registry information

Important dates

Study start
2013
Primary completion
2015
Study completion
2016
First posted
Oct 20, 2015
Registry last updated
Jan 19, 2018

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.

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