Lung Ultrasound Assessment of Postoperative Atelectasis After Mechanical Ventilation With Minimum Driving Pressure

Lung Ultrasound Assessment of Postoperative Atelectasis After Mechanical Ventilation With Minimum Driving Pressure

Brief summary The goal of this clinical trial is to compare two different types of perioperative mechanical ventilation (MV), specifically Protective Mechanical Ventilation (PMV) and MV with the lowest possible Driving Pressure (ΔP), in relation to the appearance of postoperative lung closing, eg atelectasis, in adult patients who are operated. Atelectasis will be evaluated via lung ultrasound.

The main questions it aims to answer are:

• Is MV with lower ΔP better than conventional PMV in keeping lungs more open perioperatively and immediately postoperatively?
• Does MV with lower ΔP decrease hospital stay, Intensive Care Unit (ICU) need and mortality?

Researchers will use lung ultrasound to compare MV with the lowest possible Driving Pressure (ΔP) to Protective Mechanical Ventilation (PMV) to see if any of this is more protective than the other concerning lung atelectasis.

All participants will receive perioperative MV.

Half of them will receive conventional Protective Mechanical Ventilation (PMV). This will include well known generally protective settings for mechanical ventilation of patients, concerning volumes, pressures, respiratory rate, inspiratory gases and ventilation maneuvers.

The rest of participants will be ventilated with the lowest possible Driving Pressure (ΔP). This will be similar to PMV in the chosen volumes, respiratory rate, inspiratory gases and ventilation maneuvers. However, the pressure inside lung at the end of expiration, eg Positive End Expiratory Pressure (PEEP), will be not be preset for every patient. Initially, we will perform a maneuver that will quantify each individual's lung characteristics and mechanics. According to this, we will find the exact PEEP that seems to suit each patients lungs most, and use this perioperatively, trying to provide lungs the best conditions every time.

After the completion of the operation, all the patients will be screened for atelectasis, via lung ultrasound, using a well established protocol for the quantification of atelectasis. The results will be statistically analyzed trying to find if any of the forementioned strategies of mechanical ventilation surpasses the other concerning atelectasis appearance.

Furthermore efficiency of lung oxygen absorption, hospital stay, ICU need and mortality will be noted.

Inclusion Criteria:

• >17 years old
• Surgery with general anesthesia & invasive mechanical ventilation
• ASA score I-III

Exclusion Criteria:

• <18 years old
• Preoperative ARISCAT score estimation <26
• Women during pregnancy or just given birth
• Other type of anesthesia (Not general)
• Contraindication of administration of neuromuscular blockade agents.
• Contraindication of cease of spontaneous ventilation.
• Mechanical ventilation without endotracheal intubation.
• Severe heart failure / History of ischemic heart disease.
• Moderate or severe chronic obstructive lung disease or interstitial lung disease.
• History of operation in heart, lung or diaphragm.
• Presence of new active pathology in respiratory system at the beginning of surgery (infection / trauma / anatomic disorder).
• Severe intraoperative respiratory complication (laryngospasm / bronchospasm / anaphylaxis).
• Immediate postoperative need for continuation of IMV.
• Patient denial of participation in the trial.