What is Pulmonary Edema?
Pulmonary edema is a condition where excess fluid builds up in your lungs, specifically in the areas usually filled with air. This buildup of fluid means your lungs can’t exchange oxygen and carbon dioxide as easily, which can lead to breathing problems and, in severe cases, respiratory failure — a serious condition where your lungs can’t provide your body with the oxygen it needs. Pulmonary edema can be caused by heart problems that make it hard for your heart to pump blood out of your lungs, or by damage to your lung tissue. This condition often plays a part in a variety of diseases, so understanding the root cause is crucial for treating it effectively. Symptoms of pulmonary edema can include gradually increasing shortness of breath, a crackling sound in your lungs when a doctor listens with a stethoscope, and increasingly low levels of oxygen in your blood.
What Causes Pulmonary Edema?
Pulmonary edema, a condition where fluid fills up your lungs, can be divided into two main types. These types are called cardiogenic and noncardiogenic pulmonary edema.
Cardiogenic pulmonary edema happens when the pressure in your lungs’ blood vessels rises quickly. This is usually related to issues with the left part of your heart and can happen when your heart’s function is weakened due to disease (such as a heart infection or other heart diseases) or a sudden blockage (such as a heart attack). Problems with your heart valves (like aortic/mitral regurgitation and stenosis, which is when the valves don’t open fully or leak) and irregular heart rhythms (like atrial fibrillation with a fast heart beat, a particular kind of heart rhythm disorder, or a complete heart block) can also cause this type of pulmonary edema.
Noncardiogenic pulmonary edema, on the other hand, is due to a lung injury. This injury increases the permeability, or allows more stuff to pass through the walls of your lung blood vessels. This results in the movement of protein-filled fluid into the spaces of the lungs and the surrounding tissue. If you have a severe low-oxygen situation caused by lung injury, it’s referred to as acute respiratory distress syndrome (ARDS). This can occur because of conditions directly affecting the lungs, like pneumonia or inhalation injury, or indirectly, such as blood poisoning (sepsis), inflammation of the pancreas (acute pancreatitis), severe physical trauma with shock, or after receiving multiple blood transfusions.
Risk Factors and Frequency for Pulmonary Edema
Every year, over 1 million people are hospitalized due to pulmonary edema, a condition related to heart failure. It’s estimated that 190,000 patients annually are diagnosed with acute lung injury. There are also 1.5 to 3.5 diagnosis cases of ARDS per 100,000 population.
Signs and Symptoms of Pulmonary Edema
If someone is struggling with progressively worsening shortness of breath, rapid breathing, and crackling sounds in their lungs, alongside lower levels of oxygen in their blood, they may have pulmonary edema. This condition, which involves fluid build-up in the lungs, can be caused by problems with the heart (cardiogenic) or other issues (non-cardiogenic).
The person might cough up pink, frothy mucus due to lack of oxygen from too much fluid in the air sacs within their lungs. If they also have a certain heart rhythm (an S3 gallop when a doctor listens to the heart), this might indicate that the edema is due to heart problems. Other signs of a heart-related issue can include abnormal heart sounds, elevated pressure in the neck veins, and swelling in the limbs.
For those with non-heart related pulmonary edema, doctors will look out for signs of infections like fever, cough with sputum, or shortness of breath that could suggest pneumonia. They’ll also investigate any recent injuries or blood transfusions since these could cause the patient to develop a severe lung condition known as acute respiratory distress syndrome.
When it comes to checking patients with respiratory symptoms, doctors primarily rely on using a stethoscope to listen to their breathing. They listen for either fine or coarse crackling sounds, which can help determine how to proceed with treatment. Fine crackles, which are exclusively heard during the inhalation phase when the small airways abruptly open after being closed during exhalation, are a key feature of cardiogenic pulmonary edema.
Testing for Pulmonary Edema
If your doctor suspects that you have a heart problem or a heart attack, one of the first things they might do is an electrocardiogram. It’s a simple and affordable test that picks up any unusual electrical activity in your heart. It’s usually done at your bedside during the examination.
When your doctor thinks you might have fluid build-up in your lungs (also known as pulmonary edema), they have several tests at their disposal.
One of those tests involves checking the levels of a hormone called BNP in your blood. BNP is released by your heart when it’s under strain, such as when there’s more blood in it than usual or when the blood pressure inside your heart is too high. Both of these conditions can result from heart failure. If your BNP level is below 100 pg/ml, this suggests heart failure is unlikely. If it is higher than 500 pg/ml, heart failure is highly likely. Levels in between these do not give a clear diagnosis and are often seen in severely sick patients.
We can also see an elevated level of troponin, a protein found in heart muscle cells, in patients with heart attacks or severe infections.
Another test your doctor might use involves checking the level of albumin in your blood. Albumin is a protein that helps prevent fluid from leaking out of your blood vessels. If your albumin levels are low (less than or equal to 3.4 g/dL), this can indicate a higher risk of death for patients with worsening heart failure.
Besides these, you may also have tests to check your electrolytes, kidney function, and for any toxic substances that might have caused the fluid build-up in your lungs. Your doctor may test for lipase and amylase enzymes to confirm or rule out pancreatitis, which is inflammation of the pancreas.
Radiology tests, involving taking photographs of your body using different types of light, can provide significant cues in identifying the cause for fluid in your lungs. For instance, heart-related fluid build-up typically displays as a central pattern with other features suggestive of heart failure. On the other hand, non-heart-related causes display a different, ‘patchy’ pattern. These may be tested using standard standing or portable imaging techniques.
An echocardiography, a kind of ultrasound imaging of your heart, can give valuable insight into the functioning of your heart’s ventricles (lower chambers) and its valves.
Another technique growing in popularity is the lung ultrasound. This method, often used in the ER, ICU or in the Operation Theatre, detects excess water in your lungs before your symptoms become apparent.
In cases where a clear cause for the fluid in your lungs is not identifiable, invasive procedures such as Pulmonary Artery Catheterization can be used. This test helps in tracking blood pressure within the arteries of your lungs, blood flow and resistance in your arteries. An elevated value over 18 mm Hg can suggest fluid build-up due to heart-related reasons. Another invasive technique, used most commonly during intensive surgeries, is the Transpulmonary Thermodilution. It measures several crucial parameters related to heart and lung performance in those undergoing major surgery or in shock from severe infections.
Treatment Options for Pulmonary Edema
The goal in treating pulmonary edema, which is a condition characterized by the accumulation of fluid in the lungs, is to relieve symptoms and treat the underlying cause.
Diuretics, commonly referred to as “water pills,” are often the primary treatment. Furosemide is a common diuretic medication used. While higher doses can help improve breathing difficulties, they can also temporarily affect kidney function.
Vasodilators, which help to widen blood vessels, can also be used alongside diuretics. Intravenous nitroglycerin is the preferred vasodilator; it helps reduce blood pressure and pulmonary congestion. However, it’s only safe to use when the systolic blood pressure (the pressure in your arteries when your heart beats) is above 110 mm Hg. Other drugs that help vasodilation include nesiritide and serelaxin. Clevidipine, a very short-acting medication belonging to the group called calcium channel blockers, is associated with shorter hospital stays, improved breathing difficulties, and less intensive care unit (ICU) admission when started early.
Nifedipine, another calcium channel blocker, is used to prevent and treat high altitude pulmonary edema (HAPE). It counters the constriction (narrowing) of blood vessels in the lungs caused by low oxygen levels. This action lowers the pressure inside the lungs’ arteries, which in turn improves the exchange of gases, physical capacity, and chest X-ray results. Nifedipine is only utilized when a person is at a high risk of developing HAPE and cannot adapt to the high altitude. Such risks include rapid altitude climbing, significant physical exertion, recent respiratory infections, and low native altitude of residence.
Inotropes, a type of drugs that enhance the heart’s ability to contract like dobutamine and dopamine, are used for managing pulmonary congestion when the patient has low blood pressure and evidence of poor tissue perfusion. Common side effects of these drugs include fast heart rates, heart and chest pain, and low blood pressure. Milrinone is another inotrope that can also widen blood vessels but might increase mortality risk post-discharge.
Morphine can also be used to treat pulmonary edema associated with acute coronary syndrome. It helps to reduce blood vessel resistance and acts as a painkiller and anti-anxiety medication. Still, it might depress breathing resulting in the need for a breathing tube, and it’s typically not recommended.
Support for ventilation (breathing), either noninvasive (external) or invasive (inside the body), is used to improve oxygen levels, help to remove fluids from the lungs, improve high carbon dioxide levels in the body and support tissue oxygenation. It also reduces the effort needed to breathe. Whether to provide ventilatory support depends on a patient’s response to medications, mental status, and energy levels. For patients on invasive mechanical ventilation, it’s crucial to continuously monitor their heart’s measures because decreasing the venous return to the heart can reduce the output and cause a drop in blood pressure. If noninvasive mechanical ventilation is started early it can help avoid muscle fatigue associated with breathing and decrease the need for invasive ventilation.
What else can Pulmonary Edema be?
Some possible causes for water-filled lungs (pulmonary edema) can include:
- Drowning (immersion pulmonary edema)
- Stroke or head trauma (neurogenic pulmonary edema)
- Reactions to medications or harmful substances
- Blood transfusions causing a specific lung injury (transfusion-related acute lung injury or TRALI)
- Liver disease
- Blood clot in the lung (pulmonary embolism) or lung tissue death (infarct)
- High levels of waste products in the blood due to kidney disease (uremia)
What to expect with Pulmonary Edema
Pulmonary edema, which is a condition where fluid builds up in your lungs, can be caused by either heart-related problems or other non-heart related issues. This often leads to an acute state of health distress. To help manage symptoms, such as difficulty breathing and low levels of oxygen in the blood (hypoxemia), doctors might use treatments like extra oxygen, water pills (diuretics), special medication (nitrates), and pain relief (morphine). However, to prevent future episodes, it’s crucial to identify and treat whatever is causing your condition.
It’s challenging to provide a general prediction on a patient’s outcome, given the many heart-related and non-heart related causes of pulmonary edema. Each of these causes has different risk of death associated with it. It’s worth noting that outcomes have been improving for conditions like ARDS (Acute Respiratory Distress Syndrome), which is a severe form of pulmonary edema. The hospital death rate related to ARDS has fallen from 60% between 1967 and 1981, to between 30% and 40% in the 1990s. Long-term studies of ARDS have also indicated about a 1.1% annual decline in overall mortality rate from 1994 to 2006.
However, the prognosis for each patient varies mainly based on what caused the ARDS to occur. As such, doctors typically evaluate patients on a case-by-case basis to provide the most accurate prognosis possible.
Possible Complications When Diagnosed with Pulmonary Edema
Pulmonary edema, a condition where fluid fills up in the lungs, can be complicated because it involves multiple bodily processes. This can involve the heart, liver, multiple organs, or can be the result of harmful substances. The complications from pulmonary edema usually stem from these malfunctions in the body.
If the edema is brought on by a heart-related issue, it can potentially lead to extreme difficulty in breathing that might necessitate the use of a machine to help in breathing. Another complication that one might face, if suffering from acute damage to the lungs, is ARDS (Acute Respiratory Distress Syndrome). It’s a severe condition where there is insufficient oxygen in the body, and it also generally requires the use of a breathing machine.
Key Complications:
- Complications due to heart, liver, or multiple organs
- Complications due to harmful substances
- Progression to extreme difficulty in breathing requiring a breathing machine
- Severe acute damage to the lungs leading to Acute Respiratory Distress Syndrome
- Acute Respiratory Distress Syndrome requiring the use of a breathing machine
Preventing Pulmonary Edema
Patients who have a history of heart disease, specifically blockages in the heart’s blood supply (ischemic) or issues with the heart’s valves (valvular), need to be informed about the signs of fluid build-up in the lungs (pulmonary edema) during every doctor’s visit. It’s crucial for these patients to understand the importance of following a diet low in salt, keeping a regular exercise regimen, and taking their prescribed medication regularly. These steps are essential for managing their condition.
