Overview of Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19
The Coronavirus disease of 2019, better known as COVID-19, has triggered a worldwide pandemic. The disease has spread to about 158 million people across the globe, and it has resulted in around 3.3 million deaths. COVID-19 is quite contagious and can cause severe illness, which has led to a large number of infections. This has put great stress on the healthcare systems of certain countries, to the point where they have almost broken down.
In this explanation, we’ll focus on the severe cases of COVID-19 that require the use of a ventilator. A ventilator is a machine that helps a person breathe when they are unable to do so on their own. There are also some instances where even more intensive life-saving measures need to be taken. This advanced treatment is known as extracorporeal membrane oxygenation or ECMO. This is a procedure that uses a machine to take over the work of the lungs (and sometimes also the heart).
Anatomy and Physiology of Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19
The SARS-CoV-2 virus, which caused the COVID-19 pandemic, is a type of virus called RNA virus. It has four key proteins that help make it so harmful. One of these is called the spike protein, which sticks out from the virus and lets it attach to cells in our bodies. This attaching action takes place on ACE 2 receptors, which can be found in a lot of places in our bodies like the back of our nose and throat, and lungs, but also in our digestive system, kidneys, and eyes.
Once the virus has attached, it can get inside our cells. At first, our immune system doesn’t notice the virus, so the virus can multiply unseen. However, after a while, our immune system starts to fight the virus, by identifying the spike proteins and launching a full-blown attack. During this attack, our immune system releases substances, called cytokines, that cause inflammation and can damage the lungs and air sacs. This can result in what’s called ‘an overactive immune response’ which is a situation where our immune system’s defenses start injuring our own body cells. This overactive immune response, along with certain contributing factors, such as severe decrease in certain white blood cells and release of other harmful substances, has been linked with severe COVID-19 infection and death. Blood clotting and inflammation issues have also been spotted in severe COVID-19 cases, leading to damaged oxygen circulation.
In severe COVID-19, lung injuries and inflammation can cause fibrosis or scarring. This may result in two types of lung-related problems that have been identified, one where the lungs are more flexible and another where the lungs are stiffer and heavier, similar to severe lung injury or ARDS (Acute Respiratory Distress Syndrome). However, these patterns or “phenotypes” have also been questioned and it’s suggested that what’s seen might rather be different stages of the same disease, and that severe COVID-19 acts a lot like ARDS, which is a severe form of lung injury.
Why do People Need Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19
If someone is very sick with COVID-19, they might need help breathing. One way that doctors can do this is by using a machine called a ventilator. This machine pushes air into the lungs, which can help if someone is having a lot of trouble breathing.
Doctors might decide that someone needs a ventilator if they don’t improve after getting lots of oxygen in other ways, like through a mask or nose tube. It’s also used if a patient can’t protect their airway because of a lot of mucus or abnormal mental status. If the person’s blood pressure is too unstable or can’t breathe out carbon dioxide, a ventilator might be needed.
Before putting someone on a ventilator, doctors often use a tool called a high flow nasal cannula (HFNC). This tool delivers a high amount of humidified oxygen through the nose to help the sick person breathe better. Studies have shown it’s a useful tool to help avoid having to use a ventilator.
But sometimes, if a person’s breathing doesn’t improve enough with the HFNC, then doctors might need to switch to more aggressive methods, like putting them on a ventilator. They keep a close watch on things like oxygen levels, rate of breaths, and heart rate, with a scale called the ROX index. If scores are too high or too low, it means the lungs are getting too damaged and might fail, so moving to a ventilator becomes important.
Also, besides a ventilator or HFNC, doctors might try a method known as non-invasive positive pressure ventilation (NIPV). Its goal is to make patients comfortable and lessen the amount of work they have to do to breathe. This method is often considered if a person struggles with conventional oxygen support.
In extreme situations, when all other methods fail, doctors might use an advanced life support method called Extracorporeal Membrane Oxygenation (ECMO). This method uses a machine to do the work of a patient’s heart and lungs, providing both oxygen support and circulatory support. Although not everyone will benefit from this treatment, for some, it may be life-saving.
When deciding on whether to use HFNC, NIPV, a ventilator, or ECMO, doctors keep a very close eye on all symptoms and will adjust the treatment plan to what fits the patient’s needs best. Knowing when to make these decisions is a crucial part of helping the patient recover from COVID-19.
When a Person Should Avoid Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19
Some patients with breathing problems might not need invasive mechanical ventilation (a ventilator that uses a tube inserted into a person’s windpipe). If non-invasive breathing aids like High Flow Nasal Cannula (HFNC) or Non-Invasive Positive Pressure Ventilation (NIPV) are working well for them, it’s often better to avoid the risks associated with more invasive methods.
The type of care should be based on what the patient wants and their overall health situation. It’s important to have open and empathetic conversations with the patient and their family when it seems that endotracheal intubation (inserting a tube down the throat into the windpipe) might be needed soon. This conversation should cover all the pros and cons.
In some cases, endotracheal intubation should not be used. This is especially true if the patient has made it clear that they do not want to be intubated or resuscitated (brought back to life) if their health gets worse. Their expressed desire to avoid these interventions (known as do not intubate/DNI or do not resuscitate/DNR orders) should always be respected.
For another procedure called ECMO (Extracorporeal Membrane Oxygenation, which is a heart-lung machine that takes over the functions of the heart and lungs), there are some limits on who it can help. Some of these limits are universally accepted (absolute contraindications) and some are dependent on the hospital’s policies or the evolving situation (relative contraindications).
Equipment used for Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19
The sudden increase in seriously ill COVID-19 patients has required many hospital wards to turn into specialized intensive care units (ICUs) that can isolate and treat these patients effectively.[25] The high number of ICUs and the demands put upon them can be linked to higher patient death rates. Therefore, it’s crucial to improve how efficiently patients are treated and move through the hospital.[26]
These ICUs should have a regular and reliable supply of medical oxygen capable of supporting high flow oxygen machines and mechanical breathing machines, or ventilators. They also need designated areas with separate tools for a common procedure of placing a breathing tube into a patient’s windpipe, known as endotracheal intubation. This setup should include the necessary protective clothing (PPE), like gloves, a gown, a high-filtration mask called an N-95, and a face shield, to protect the healthcare team from being exposed to the virus.
Depending on what is available, a special respirator that can purify the air they now breathe (PAPR) should be considered for the team, because placing a breathing tube into a patient’s windpipe can produce a lot of airborne particles carrying the virus.
Treating COVID-19 patients who are having difficulty breathing and placing a breathing tube should be done by healthcare professionals who have a lot of experience with these tasks. They should aim to get the tube in one try to minimize the chance of spreading the virus. Devices that provide a clear video-feed of the throat to help place the tube are recommended as they allow the healthcare professional to maintain a safer distance from the patient’s mouth. These professionals need to be trained on how to use these devices effectively in the ICU. Some have used a clear plastic shield, or “intubating box” to reduce the spread of airborne particles during this procedure, but it’s unclear if this actually leads to less exposure to the virus.
Healthcare staff should also use the necessary protective clothing (PPE), including gloves, gowns, an N-95 mask, and face shields, to protect themselves from getting the virus. As the pandemic progresses, it’s increasingly important to not waste PPE and take steps to prevent unnecessary contact with healthcare staff and the virus. Simple tools like longer tubes can be used to connect medicine pumps to patients and keep the pumps outside of the patient’s room. The same goes for the cords of ventilation screens, allowing regular changes to the ventilator without needing to enter the patient’s room.
Special rubber rings, known as grommets, have been made for doors in ICU rooms. These rubber rings would allow wires and tubes to pass through the door securely while maintaining the room’s isolation. The aim is to prevent virus-filled air from leaving the patient’s room and spreading throughout the hospital. An example is shown in Figure 5 of a widely available grommet that could be placed on ICU doors. Special air filters that can catch very small particles, known as HEPA filters, should be used for each room with a patient on a ventilator to reduce the spread of the virus within the hospital. These filters should be checked daily and replaced as needed.
Support for failing lungs or hearts, termed ECMO, requires special equipment and a dedicated nurse for every patient. Regularly keeping track of the equipment and staying in constant contact with doctors and perfusionists who control the blood flow is crucial for safe ECMO operation. Should an emergency occur, it’s essential to have extra ECMO tubes, artificial lungs, cannulas (tubes inserted into the body), and a backup set of equipment readily available.
Who is needed to perform Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19?
When a patient needs help with their breathing and is on a mechanical ventilator or ECMO (a machine that helps with heart and lung function), many healthcare professionals work together to make sure the patient gets the best care possible. This team might include:
* A doctor who specializes in caring for seriously ill patients in the hospital (an “intensivist”) or a surgeon
* Other medical professionals who give advice about the patient’s care (“consulting providers”)
* Specialized healthcare providers who work under a doctor’s supervision (“advance practice providers”)
* A nurse who has special training in caring for very sick patients (“critical care trained nurse”)
* A healthcare professional who helps patients breathe more easily (“respiratory therapist”)
* A person who operates the ECMO machine (“perfusionist”)
* A pharmacist who knows a lot about the medicines used in the critical care area (“critical care pharmacist”)
* Therapists who work with the patient to help them move and do everyday tasks (physical/occupational therapists).
This group of professionals work together as a team to make sure the patient gets the best care while they’re in the hospital.
Preparing for Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19
Endotracheal intubation and IMV, or Invasive Mechanical Ventilation, are procedures that help a patient breathe when they can’t do so on their own. To prepare for these, it’s important that everyone on the healthcare team communicates clearly with each other. The team usually includes a respiratory therapist, who specializes in helping with breathing issues; an intensivist, who is a doctor specializing in intensive care; a nurse; and an ICU pharmacist.
Before these procedures, the team will take a “time-out” to review details about the patient and the planned steps unless it’s an immediate life-threatening situation. They will also discuss pre-oxygenation, which means giving the patient extra oxygen before the procedure. They may use devices like high flow nasal cannulas (HFNC), non-rebreather masks, or in some cases, non-invasive positive-pressure ventilation (NIPV) to prevent low blood-oxygen levels during the procedure.
The team will also consider the patient’s allergies, previous intubations, and any reasons they may not be able to take certain medicines. Most of the time, they’ll use a procedure called rapid sequence intubation and a device called a video laryngoscope. This helps the doctor see the throat and windpipe on a screen so they can guide the tube more efficiently, and it reduces the risk of spreading airborne particles.
The team will try to keep the patient’s muscles fully relaxed to prevent coughing and increase the likelihood of a successful procedure. The most skilled and experienced healthcare provider will normally carry out the intubation to reduce risk and increase efficiency.
How is Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19 performed
Ventilators are machines that help people breathe when they can’t do it on their own. When treating patients with the COVID-19 virus, doctors may need to use a ventilator. Doctors use a specific approach, called lung-protective ventilation (LPV), which helps in preventing damage that a ventilator can potentially cause to the lungs. There are three main parts of this strategy: avoiding overfilling the lungs with air (alveolar overdistension), preventing damage from too much oxygen (hyperoxia), and stopping the lungs from repeatedly collapsing and reinflating (cyclical alveolar collapse).
To avoid overdistension, doctors use a method called ‘low tidal volume ventilation’. Just like waves have different sizes (or ‘tidal volumes’), our breath can have different sizes too. When our lungs are damaged—like from the COVID-19 virus—filling them with large ‘waves’ of air can cause harm. The key is to fill the lungs with smaller waves which help in reducing the damage.
We might think the more oxygen in our lungs, the better. But too much oxygen can actually harm the lungs. Just like a purring engine, our lungs need a specific mixture of air to work well. That mixture is mostly nitrogen with a little bit of oxygen. However, a ventilator can sometimes give too much oxygen and not enough nitrogen, causing the small airways in our lungs to collapse. Therefore, doctors constantly check our oxygen levels to keep them at a safe level.
Doctors may also turn a patient onto their stomach, a process called ‘prone positioning’, which can help improve oxygen levels in serious cases of lung damage. Patients are typically placed in this position for at least 16 hours, but doctors are cautious during the process to avoid any accidents that could harm the lungs further.
Medication may also be used to help a patient’s body work better with the ventilator. These medications, called neuromuscular blocking agents (NMB), help to smooth out any mismatch between the patient’s breathing and the rhythm of the ventilator. However, doctors try to limit the use of these medications unless absolutely necessary.
In severely critical cases, doctors may also use a treatment called ECMO (Extracorporeal Membrane Oxygenation). This is a machine that pumps oxygen-rich blood into the body, just like the heart and lungs would do. This procedure is a last resort to help the patient breathe.
Possible Complications of Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19
When a patient has positive pressure applied to their airways, too much pressure can cause barotrauma, or damage to the lungs from the pressure. This can be dangerous and impact the patient’s chance of survival, with one of the big concerns being the development of a pneumothorax or a collapsed lung. A pneumothorax can then further raise the airway pressure, causing more parts of the lung to deflate and creating worse oxygen levels in the body. It can also result in a tension pneumothorax, which can impact blood flow to the heart and can be life-threatening.
To quickly diagnose a pneumothorax, particularly in a critical situation, doctors can perform a bedside ultrasound scan, even while an urgent chest x-ray is being prepared. A normal scan will show the lungs moving against the chest wall. If this movement isn’t visible, doctors might intervene to relieve the pneumothorax, even before the x-ray results are back.
For a critical condition called tension pneumothorax, doctors can use a procedure involving a large needle to release the air from the chest – this can save a life. After the emergency is stabilized, more lasting treatments like a special catheter or a chest tube may be used to remove the air from the pneumothorax.
One challenge that doctors look out for is a bronchopleural fistula, or a rare complication where a hole forms between the lung and the chest wall. If this is suspected all these treatments haven’t resolved the pneumothorax, a chest surgeon may be brought in to help manage the condition.
Patients who are treated with an endotracheal tube, or a tube inserted into the windpipe through the mouth or nose, may be subject to injury that can cause a condition where blood is coughed up. To minimize risk, a respiratory therapist will usually handle the process of suctioning, or removing unwanted secretions, from the tube. Patients showing signs of infection while on a ventilator will be monitored for ventilator-associated pneumonia – a common type of pneumonia that develops in patients on ventilators.
If a treatment called ECMO (extracorporeal membrane oxygenation) cardio-pulmonary life support is used, the patient will be carefully selected and monitored due to the significant risks. ECMO has been linked with life-threatening bleeding due to the effects of the blood thinners required for the treatment. Other risks include clotting and issues with the ECMO catheters. All these need to be managed by frequent monitoring and interprofessional discussion.
What Else Should I Know About Mechanical Ventilation and Extracorporeal Membrane Oxygenation Considerations in COVID-19?
Since the start of the pandemic, medical professionals have been working on structured ways to treat severe lung disease (ARDS) caused by COVID-19. Due to the rapid spread of the virus and limited resources, it was initially challenging to implement a standard treatment plan for COVID-19 patients. Additionally, the guidelines for managing COVID-19 kept changing and varied across different regions, causing confusion among healthcare workers. However, as our understanding of the virus has advanced, we’ve been able to develop more effective treatment protocols.
Patients with moderate to severe lung disease caused by COVID-19 (ARDS) need custom-tailored treatments after their hospital admission. One key aspect is regulating the immune response to the virus to prevent it from damaging the lungs and causing widespread inflammation. Medications like corticosteroids and Baricitinib can help control this immune response and reduce the patient’s need for oxygen. The severity of the lung disease is gauged using the Berlin criteria.
Patients who can’t breathe on their own and have to be put on a ventilator, medical teams should take proper safety measures and aim for a smooth and successful first attempt at insertion. The treatment team should have well-defined roles and work collaboratively to ensure the best patient care. Once the patient is on a ventilator, steps like using low-volume breath cycles and tilting them onto their stomach should be taken. Using these methods has been shown to improve survival rates. Medication can be used to prevent uncoordinated breathing and improve synchronization between the patient and the ventilator. The patient will gradually be weaned off the ventilator and other supports as their condition improves.
If a patient’s condition worsens and they’re not benefiting from the ventilator, they might need to be put on an ECMO machine that pumps and oxygenates their blood outside of the body. Planning is crucial here – for instance, the patient’s right internal jugular vein should be kept clear for smooth insertion of the ECMO machine’s catheter if needed. The focus should be on anticipating future steps and sharing knowledge to provide the best possible care and reduce the high death rates associated with severe COVID-19 lung disease.
