What is Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)?
Barotrauma is a condition where body tissues get damaged due to pressure changes within the body’s enclosed spaces. You can notice barotrauma in people who often engage in scuba diving, free-diving, or even airplane passengers during take-off and landing.
Though barotrauma can affect various body organs, one of the most common cases is in the middle ear, sinuses, and lungs, referred to as pulmonary barotrauma, which is what this article is focused on.
Pulmonary barotrauma is a potential complication of artificial or mechanical breathing methods, which are linked to higher health risks and mortality rates. The normal human breathing mechanism functions on negative pressures within the chest cavity. However, artificial breathing techniques like mechanical ventilation rely on pushing air in with positive pressure, which is an abnormal situation and can lead to complications such as barotrauma.
Pulmonary barotrauma occurs when there is an abnormal presence of air outside the alveoli, the tiny air sacs in our lungs. This abnormal presence of air is primarily triggered by a rupture of the alveoli, leading to air accumulation in unintended places. Consequently, the excess air can result in complications like a collapsed lung (pneumothorax), air in the mediastinum (pneumomediastinum), and air under the skin (subcutaneous emphysema).
There are different types of mechanical ventilation, such as invasive and non-invasive methods, including bilevel positive airway pressure. Interestingly, the chances of getting barotrauma is significantly lower in patients undergoing non-invasive mechanical ventilation compared to those on invasive methods. People particularly at risk of barotrauma from mechanical ventilation include those with pre-existing lung conditions such as chronic obstructive pulmonary disease (COPD), asthma, interstitial lung disease, pneumocystis jiroveci pneumonia, and acute respiratory distress syndrome (ARDS).
What Causes Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)?
Pulmonary barotrauma can occur during mechanical ventilation when the pressure inside the lungs becomes too high, causing air sacs to burst. Certain health conditions, such as COPD and asthma, can increase the risk of this happening. Obstructive lung diseases can lead to overinflation of the lungs, making it harder for patients to exhale all the air before the ventilator pumps in the next breath. This can result in increased pressure in the lungs, raising the risk of barotrauma. Healthcare professionals can adjust the ventilator settings to manage this risk. Elevated plateau pressures and peak pressures can also increase the risk of barotrauma. However, high positive end-expiratory pressure (PEEP) does not seem to raise the risk of barotrauma when used with lung-protecting strategies. If higher PEEP is needed, it should be increased slowly and monitored closely.
Risk Factors and Frequency for Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)
The rate of lung damage, also known as pulmonary barotrauma, in patients given mechanical ventilation greatly varies, with estimates ranging from 0% to 50%. However, recent studies, following the introduction of lung protection methods in ventilations, suggest that the average incidence might be around 10% among different population groups.
A study conducted in 2004 involved 5183 patients from 361 intensive care units (ICUs). It found that the average incidence of barotrauma was 2.9%. The study also found that the rate varied depending on the reason for mechanical ventilation.
- The rate was 2.9% in patients suffering from Chronic Obstructive Pulmonary Disease (COPD).
- 6.3% in patients with asthma.
- 10% in patients with Interstitial Lung Disease (ILD).
- 6.5% in patients with Acute Respiratory Distress Syndrome (ARDS).
- 4.2% in patients with pneumonia.
Signs and Symptoms of Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)
Pulmonary barotrauma is a condition that occurs due to mechanical ventilation, often in patients who are seriously ill. The symptoms might not be very noticeable because the patients are usually sedated. However, in severe cases like a significant pneumothorax (air leak from the lungs), patients might show rapid changes in vital signs. These changes can include rapid breathing, low oxygen levels in the blood, and a fast heartbeat. If a tension pneumothorax (a severe type of pneumothorax) occurs, patients may also show signs of obstructive shock, a severe condition that can block blood flow to your organs. During a physical examination, doctors might notice that certain areas have absent breath sounds indicating a pneumothorax. Some patients may also exhibit subcutaneous emphysema, a condition where air gets into tissues under the skin. However, in less severe cases of barotrauma, there may be no evident changes in the patient’s body system or blood flow.
Also, a patient’s past medical history plays a crucial role in diagnosing and managing pulmonary barotrauma. People with chronic obstructive pulmonary disease, asthma, interstitial lung disease, pneumocystis jiroveci pneumonia, or acute respiratory distress syndrome are at a higher risk of developing pulmonary barotrauma. This information also helps clinicians select the best mode and settings of the ventilator for each patient.
Testing for Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)
Data from a ventilator can be helpful in assessing lung injury or ‘pulmonary barotrauma’. If there are signs of difficulty between the patient and the ventilator, or if there’s a quick increase in pressure above established safe levels, or an unexpected drop in the volume of air getting into the lungs, this could suggest respiratory trouble. Often, this could be due to a pneumothorax, which is a collapsed lung, or other complications from injury to the lungs. This information can help doctors figure out which patients on a ventilator are most likely to get lung injuries.
If doctors think that a patient’s lung injury is a result of using a ventilator, they need to act right away. A pneumothorax is a critical urgent complication from lung injury and must be treated immediately. When examining the patient, the doctor may notice missing breath sounds. Most patients will experience shortness of breath and chest pain. They may also have low oxygen levels and low blood pressure due to a form of shock called ‘obstructive shock’ if the pneumothorax is causing pressure. In this tension pneumothorax situation, immediate action is needed even before an X-ray can be done. This usually involves using a needle to release the built-up air, followed by placement of a tube in the chest.
For patients who have a less urgent complication, like a simple pneumothorax with stable vital signs, air in the mediastinum (the area that divides the chest cavity), or air under the skin, a chest X-ray should be obtained quickly. This X-ray can show the presence of a pneumothorax, air in the mediastinum or under the skin, and other less common signs of lung injury like air sacs, air collections under the pleura (the thin film that lines the lungs), and air in the lung tissues.
If the chest X-ray does not provide clear information, a CT scan of the chest can be performed. It’s vital to remember that lung injury is diagnosed based on clinical signs, so it should always be considered a strong possibility in patients with sudden deterioration who are on both invasive and non-invasive types of mechanical ventilation.
Treatment Options for Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)
To reduce the risk of lung damage in ventilator-dependent patients, it is important to keep inspiratory pressures low. The pressure at the end of inhalation should ideally be below 30 cmH2O, but not exceed 35 cmH2O. This can be achieved by using ventilator modes such as volume assist control or pressure assist control. Patients with conditions like ARDS, COPD, asthma, pneumonia, and chronic interstitial lung disease are at higher risk and should be monitored closely. High plateau pressures can increase death rates, while high PEEP can improve outcomes. Dynamic hyperinflation and intrinsic PEEP can occur in patients with lung diseases affecting the airways. A stress index can help determine the appropriate level of PEEP. Different ventilation modes may be better tolerated by certain patients and can reduce the risk of barotrauma.
What else can Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks) be?
Some conditions that might seem similar to each other, but are different, include:
- Severe lung condition called ARDS
- Pneumonia caused by bacteria or viruses
- Inflammation of the lungs due to inhaling foreign substances
- Various types of shock, including from heart problems, extreme blood loss, or spread of infection
- Chest injuries, like flail chest
- Chest injury leading to a punctured lung
- Blood clots in the lungs
- An asthma flare-up
- A COPD flare-up, a chronic lung disease
- Acute coronary syndrome, a medical term for a heart attack or unstable angina (chest pain)
Therefore, it’s key that doctors closely examine a patient’s symptoms and health history to accurately diagnose their condition.
What to expect with Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)
Pulmonary barotrauma, or lung damage due to pressure changes, can cause more severe illness and a higher risk of death if it happens while a patient is on a ventilator. A large study conducted in 361 intensive care units across 20 countries examined this issue. The study involved 5183 patients who were on ventilators for over 12 hours.
The results showed that 2.9% of these patients had pulmonary barotrauma. Importantly, patients who developed barotrauma faced a higher risk of death – 51% compared to 39%. So it’s clear that pulmonary barotrauma significantly impacts the patient’s medical outcome.
Possible Complications When Diagnosed with Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)
Patients who suffer from barotrauma – injury caused by changes in pressure – due to the use of mechanical ventilation, typically need to stay in the intensive care unit (ICU) and on mechanical ventilation longer. Staying on mechanical ventilation for extended periods can lead to more issues. These can include complications from barotrauma, as well as other problems like pneumonia related to ventilator usage, confusion or cognitive impairment, weakness acquired from time spent in intensive care, and infections contracted in the hospital.
- Barotrauma complications
- Ventilator-associated pneumonia
- Delirium or cognitive impairment
- Weakness acquired from the time spent in ICU
- Infections contracted in the hospital
Preventing Barotrauma and Mechanical Ventilation (Mechanical Ventilation Risks)
Patients who are alert and aware before starting mechanical ventilation should be informed about the potential risks associated with this procedure, such as lung damage, also known as barotrauma. Doctors should clearly communicate to both the patients and their families the heightened risk of illness and death linked to barotrauma, particularly for those patients with preexisting conditions such as Chronic Obstructive Pulmonary Disease (COPD), asthma, or Interstitial Lung Disease (ILD). It’s essential for healthcare providers to talk through the aims and expectations of the care plan with each patient and their family members.
