Impact of High Versus Lower Oxygen Fraction Prior to Extubation on Postoperative Pulmonary Atelectasis Measured with EIT
NCT Number: NCT06538740
Acronym: RESPIRA-EIT
Status: NOT_YET_RECRUITING
Study Type: INTERVENTIONAL
Phases: NA
Conditions: Atelectasis
Sponsor: Beth Israel Deaconess Medical Center
Sex: ALL
Age: ADULT, OLDER_ADULT
Enrollment: 24
Study Design: Allocation: RANDOMIZED|Intervention Model: PARALLEL|Masking: SINGLE (PARTICIPANT)|Primary Purpose: PREVENTION
Start Date: 2024-09
Completion Date: 2025-08

Summary:
Patients undergoing general anesthesia require mechanical ventilation (artificial delivery of air and oxygen to their lungs). It is well known that during mechanical ventilation so called atelectasis formation occurs. This is a condition characterized by partial or complete collapse of lung tissue that can result in a reduction in oxygen uptake through the lung. A known risk factor for atelectasis formation during mechanical ventilation is the utilization of high oxygen concentration as the oxygen molecules are absorbed in the lung, which then can lead to collapse of the tissue. Despite the proven association standard operating procedure at the end of anesthesia still requires utilization of 100% oxygen. Its justification is the goal to ensure sufficient oxygenation throughout the extubation phase. However, clinical observation doesn't show a lack of oxygenation in this phase but the patient is still exposed to the risk of atelectasis formation.

This study aims to investigate the hypothesis of whether the utilization of reduced oxygen concentration before extubation (70% compared to 100%) reduces atelectasis formation. Patients who participate in this study are randomly (i.e. by chance) assigned to either the control group receiving standard care (100% oxygen at the end of anesthesia), or the intervention group receiving 70% oxygen. Of note, this is still 3 times as much as when breathing "standard" room air, which has 21% oxygen. During the intervention, parameters such as the oxygen content in the blood (oxygen saturation, SpO2), heart rate and blood pressure are recorded and atelectasis formation is measured using a technique called electrical impedance tomography (EIT). EIT measurements are performed at designated timepoints during the procedure. Anesthesia care providers are asked to document procedural, patient and ventilator data in a questionnaire. Secondary outcomes are the homogeneity and distribution of air measured with EIT, as well as some clinical outcomes including post-extubation desaturation (\<90% SpO2), incidence of re-intubation or non-invasive ventilation and the Post-anesthesia Care Unit (PACU) length of stay.

Primary Outcome Measures: The shift of Center of Ventilation (CoV), measured through Electrical Impedance Tomography (EIT) in %., The Center of Ventilation (CoV) is a variable based on the EIT. It is calculated after the initial measurements and defines the most ventilated area of the lung. Assumptions on atelectasis formation can be drawn when the CoV shifts to more ventral areas than measured before. Primary outcome is the absolute difference between the first measurement (before induction) and the measurement directly after extubation in %., The CoV is measured at six points: pre-induction, post-intubation, pre-washout, pre-extubation, 1 min post-extubation, and 60 min post-extubation in the PACU. The primary outcome is the difference between pre-induction and 1 min post-extubation.
Secondary Outcome Measures: The 1st secondary outcome is the variation of the inhomogeneity index within each patient, measured through Electrical Impedance Tomography (EIT)., The inhomogeneity index is a variable based on the EIT and is calculated after the initial measurements. It defines the homogeneity of the aeration throughout the whole ventilated area and provides information on potential atelectasis formation or overventilation in certain lung areas. The outcome is the variation of the inhomogeneity index within each patient., The inhomogeneity index is measured at six points: pre-induction, post-intubation, pre-washout, pre-extubation, 1 min post-extubation, and 60 min post-extubation in the PACU.|The 2nd secondary outcome is the distribution of lung aeration, measured through Electrical Impedance Tomography (EIT)., The distribution is a variable based on the EIT and can be calculated after the initial measurements. It defines the distribution of the lung aeration throughout the whole ventilated area and can give information on potential atelectasis formation in the lung., The distribution of lung aeration is measured at six points: pre-induction, post-intubation, pre-washout, pre-extubation, 1 min post-extubation, and 60 min post-extubation in the PACU.|Minutes of hypoxemia in the first 60 minutes after extubation, It is determined as SpO2 \< 90% for more than two minutes throughout the stay in the PACU in the first 60 minutes after extubation., The SpO2 data analysis starts with the time the patient enters the PACU and is continued until the patient is discharged from the PACU, which is typically one to two hours after the end of surgery.|Re-intubation or the need for unplanned non-invasive ventilation within 7 days., It is determined as re-intubation or the need for unplanned non-invasive ventilation (NIV)., 7 days post-operative|Unplanned admission to either ICU, IMC or a normal unit., Number of patients that experience unplanned admission to either ICU, IMC or a normal unit after their PACU stay., Unplanned admission to either ICU, ICM or a normal unit after the PACU stay is determined in the time frame after end of surgery and up to 7 days after the surgery.|Length of stay in the PACU, It is determined as the length of stay in the PACU in minutes., The length of stay in the PACU is measured in minutes from admission to discharge from the PACU.