GO2 PEEP Study: Bidirectional Oxygenation Valve in Postoperative Atelectasis

GO2 PEEP Study: The Use of a Bidirectional Oxygenation Valve in the Prevention and Management of Postoperative Atelectasis

This study compares a novel breathing device, called the GO2 Mouthpiece, to the standard breathing tool called the incentive spirometer, thus improving respiratory dynamics of the postoperative patient.

Postoperative pulmonary complications (PPCs) are the principal cause of morbidity, mortality and prolonged hospitalizations in surgical patients, which results in a 50% increase in healthcare costs compared to postoperative cardiac complications. This is especially evident following cardiovascular surgery. One of the most common PPCs is atelectasis, resulting in dyspnea, tachypnea and hypoxemia. Postoperative atelectasis is a predictable consequence of anesthesia, surgical trauma, and pain associated with breathing. Methods aimed at increasing lung volume and treating atelectasis, commonly known as postoperative physiotherapy, play an important role in preventing PPCs. These methods include cough and deep breathing, continuous positive airway pressure (CPAP), postural drainage, incentive spirometry and positive end expiratory pressure (PEEP). Incentive spirometry has served as a convenient approach for the postoperative patient to sustain maximal inflations and encourage deep breathing. Although incentive spirometry is used commonly by post-operative patients, evidence fails to support its benefit. PEEP is a well-known pulmonary physiologic principle. There are on average 600 million alveoli in the lung. Each alveolus has surfactant to resist the natural propensity for these small air sacs to collapse during exhalation. Despite this surfactant, some alveoli will collapse and not be available for gas exchange. This atelectasis results in a ventilation/perfusion mismatch where alveolar units are perfused but not adequately ventilated. This is referred to as shunting and results in hypoxemia (decreased PaO2). PEEP decreases the propensity for the alveoli to collapse by increasing the air pressure in the lungs. This residual pressure in the lungs at the end of exhalation decreases shunting and allows for more complete gas exchange and improved oxygenation. In patients, PEEP is one of the safest ways to increase PaO2 and is used on almost all modern ventilator settings. The purpose of this study is to compare a novel breathing device, called the GO2 Mouthpiece, which uses the concept of PEEP, to the incentive spirometer in postoperative patients.

The incentive spirometer is a device that measures how deeply a person can inhale (breathe in). It helps with taking slow, deep breaths to expand and fill the lungs with air, which helps prevent lung problems, such as pneumonia. The incentive spirometer is made up of a breathing tube, an air chamber, and an indicator to help users control their breathing.

The GO2 Mouthpiece is a simple, comfortable, and straightforward silicone rubber-made, bidirectional oxygenation mouthpiece that effectively delivers PEEP with every breath.

Partial pressure of oxygen is a measurement of oxygen pressure in arterial blood. It reflects how well oxygen is able to move from the lungs to the blood. Normal values are 80 to 100 millimeters of mercury (mmHg).

Atelectasis is a lung condition that happens when the airways don't expand normally. Atelectasis is measured with the modified radiological atelectasis score (m-RAS). Each pulmonary lobe, including the lingula, is scored 0-3 (0=normal, 1=plate or minor infiltrate, 2= moderate atelectasis, 3= total atelectasis). The scores of the six lobes are then summed to give a total score ranging from 0 to 18 with higher scores being associated with worse outcomes. For this analysis, scores were categorized as 0 (normal) or greater than 0 (not normal). The count of participants with a normal atelectasis score at the indicated time point are presented here.

Oxygen was provided by a nasal cannula. The flow rate of supplemental oxygen that participants required after surgery is assessed as liters per minute. Higher flow rate indicates an increased need for supplemental oxygen.

Forced expiratory volume in one second (FEV1) is measured during a spirometry test, also known as a pulmonary function test, which involves forcefully breathing out into a mouthpiece connected to a spirometer machine. FEV1 is the amount of air forced from lungs in one second. To describe severity of pulmonary disease, FEV1 can be expressed as a percentage of the predicted value. Values 80% and and greater of the predicted value are considered normal.

Forced vital capacity (FVC) is measured during a spirometry test, also known as a pulmonary function test, which involves forcefully breathing out into a mouthpiece connected to a spirometer machine. FVC is the total amount of air exhaled during the FEV test. FVC can be expressed as a percentage of the predicted value.The normal range for the percent of the predicted value is between 80% and 120%.

Respiratory rate is the number of breaths taken per minute. The normal respiration rate for an adult at rest is 16 to 20 breaths per minute.

Measure of heat associated with the metabolism of the body. Normal range is between 36.5-37.5 degrees Celsius (°C).

Inclusion Criteria Undergoing coronary artery bypass surgery (CABG) and/or valve replacement surgery Able to provide written informed consent Maintenance of an arterial line postoperatively Exclusion Criteria Active smoking, within three months of surgery Forced expiratory volume in one second (FEV1) <75% predicted Relative risk to develop pulmonary barotrauma as evident by history of pneumothorax or emphysema Unable or unwilling to provide informed consent, cognitive impairment