Acute pulmonary edema is an accumulation of fluid:
- in the alveoli,
- in the interstitial pulmonary spaces.
Alveoli or alveoli are used to:
- absorb the inhaled oxygen from the air,
- to remove carbon dioxide from the blood.
The accumulation of fluid in the alveoli:
- impedes breathing,
- can lead to death.
In general, pulmonary edema occurs bilaterally, but can also be unilateral, for example, in the case of re-expansion of the lungs after pneumothorax.
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Causes of pulmonary edema
Usually, pulmonary edema is caused by heart disease, but it can also be caused by another health problem.
Cardiogenic pulmonary edema
(with increased pressure in the pulmonary capillaries)
Cardiogenic pulmonary edema is the most common form.
The main task of the heart is:
- absorb oxygen-rich blood from the pulmonary veins,
- pump blood into the body through a large artery called an aorta.
The right ventricle pumps blood to the pulmonary arteries that lead to the lungs. There, the capillaries are in contact with the alveoli to carry out the gas exchange, i.e.:
- the oxygen enters the capillaries,
- the carbon dioxide passes into the alveoli.
From the pulmonary capillaries, the blood flows into the pulmonary veins, which carry the oxygen-rich blood to the left atrium.
In some cases, the heart is unable to pump enough blood to the organs, then the blood accumulates in front of the inefficient ventricle, that is, in the pulmonary veins.
The result is an increase in pressure in these veins and in the pulmonary capillaries.
The increased pressure leads to the leakage of blood fluid into the interstitium of the lungs; this fluid accumulates and forms the interstitial pulmonary edema.
If the pressure continues to rise:
- burst the connections of the alveoli,
- the fluid penetrates into the alveoli and forms an alveolar edema.
This liquid:
- blocks the normal flow of oxygen through the lungs,
- causes shortness of breath.
Cardiac pulmonary edema is divided into:
- Low-flow pulmonary edema, when the pumping power of the heart is reduced and insufficient for the body’s needs.
- High-flow pulmonary edema, when the heart muscle pumps a lot of blood, but this is not enough because the patient has a condition such as:
- Anaemia
- arterio-venous fistulas,
- excessive amount of thyroid hormones in the blood (hyperthyroidism).
Causes of cardiac pulmonary edema include:
- Myocardial infarction
- Persistent and severe high blood pressure
- Thyroid diseases (thyrotoxicosis)
- Pulmonary arterial hypertension
- Endocarditis (infection of the heart valves)
- Left or right heart failure
- Arrhythmia (irregular heartbeat)
- Dilated cardiomyopathy
- Heart valve defects, for example mitral valve stenosis
- Congenital (congenital) heart disease, for example atrial and ventricular septal defect or wall defect of the heart chambers
- Heart failure
Non-cardiogenic or traumatic pulmonary edema (with normal pressure in the pulmonary capillaries)
Causes of noncardiogenic pulmonary edema are:
Pneumonia or pneumonia
This disease is characterized by inflammation of the lungs. Pneumonia is mainly caused by a lung infection caused by:
- Viruses
- Bacteria
- Fungi.
The damaging microbes accumulate in the alveoli. To fight the infection, the alveoli fill with pus or fluid.
These disorders can lead to a serious situation such as respiratory insufficiency if no immediate action is taken.
Liver
Excess fluid tends to accumulate in the lungs when the liver is damaged.
Alcohol abuse is one of the main causes of liver disease (for example, cirrhosis) and can lead to fluid retention:
- in the lungs,
- in the abdomen (ascites),
- in the ankles.
Lung tumor
Patients with lung cancer suffer from water retention inside and outside the lungs.
This can be seen in a chest X-ray (X-ray).
If the tumor forms in the lungs or it is a metastasis, pulmonary edema may form.
Inhalation of toxic gases and smoke
Also, contact with toxic gases such as ammonia or smoke in a fire is often not tolerated by the lungs.
Toxic gases irritate the lungs and inhalation can lead to problems such as:
- Inflammation
- Pulmonary edema.
Blood transfusions
Blood transfusions help with many serious conditions, but if this process is not done correctly, it can lead to serious complications such as pulmonary edema.
High altitudes
Alpinists can develop pulmonary edema at high altitudes if they do not use the necessary equipment.
The altitude is characterized by a reduction in oxygen in the air. This increases the pressure in the pulmonary arteries.
The result is fluid leakage from the arteries and capillaries to the alveoli.
Kidney disease
The main tasks of the kidneys are:
- purification of the blood,
- Maintenance of sodium in the circulating blood.
In kidney disorders, sodium may rise above normal levels.
Increased levels of sodium in the blood can lead to water retention (edema) in any area of the body, including lungs.
Chronic renal insufficiency can lead to uremic lung, an interstitial lung disease that, in addition to pulmonary edema, provokes inflammation and fibrosis of the interstitium of the lungs.
Other causes of noncardiogenic pulmonary edema:
- Allergic reaction (pneumonia caused by hypersensitivity)
- Acute pancreatitis
- Eclampsia
- Septic shock
- Pneumothorax (air in the pleural cavity)
- Inhalation of stomach acid or water (drowning)
- Poisoning (for example, by snake venom)
- Current pneumonia caused by radiation.
- Excessive toxin exposure, alcohol abuse, or excessive heroin use
- Beriberi (lack of vitamin B1)
The most common causes of noncardiogenic pulmonary edema in the elderly are:
- malignant lung tumor,
- Kidney or liver disease.
Neurogenic pulmonary edema
Neurogenic pulmonary edema occurs after severe damage to the central nervous system.
Causes include:
- ischemic or hemorrhagic stroke,
- Cramps
- Cranial trauma.
Symptoms of pulmonary edema
Patients with pulmonary edema have:
- rapid breathing,
- abnormal heart murmurs,
- Shortness of breath or wheezing after exertion.
After physical exertion, the patient is unable to breathe normally.
In general, pulmonary edema provokes the following symptoms:
- Sudden shortness of breath, which increases in a lying position. The patient feels better sitting because the fluid flows downwards due to gravity and the upper part of the lung remains free to breathe.
- Breathing acceleration
- Fatigue
- Excessive sweating
- Skin pallor
- Persistent cough with foamy, reddish or bloody tinged sputum
- Hissing sound during breathing
- Rattling breathing sounds, wheezing
- Fear and restlessness
- Sudden anxiety when lying down
In the absence of immediate treatment, the above symptoms progressively worsen and it occurs:
- Haemoptysis
- Bluish and sweaty skin
- Leg swelling (swollen ankles and feet)
- Fluid accumulation in the abdomen (ascites or dropsy)
- Abnormal heart murmurs
- Tachycardia: heart rate is faster than normal
- Chest pain
- Paroxymal nocturnal dyspnea: sudden shortness of breath during the night, as a result of which the patient wakes up
- Rattling sounds in the lungs that spread from the base to the tips of the lungs.
- Inability to speak longer sentences seamlessly
- Inability to sleep flat (minimum 2 pillows required)
- Mental confusion
- Swollen and painful liver
- Weakness
Diagnosis of pulmonary edema
Diagnosis is made by an examination that includes:
- clinical history,
- Eavesdropping (auscultation) of the heart and lungs.
Often the patient comes late to the hospital because he ignores the deterioration of his state of health.
You should consult a doctor if you notice that you have more problems climbing stairs.
Imaging examination methods for pulmonary edema
1. X-ray
An X-ray is required to reveal lung function.
X-rays indicate:
- Bronchitis
- pulmonitis,
- Asthma
- enlarged heart.
2. Electrocardiogram (ECG), allows the determination of:
- Ischemia
- hypertrophy of the left ventricle,
- Cardiac arrhythmia (arrhythmia).
3. Echocardiography (cardiac ultrasound diagnostics)
The test is used to examine various heart problems, including:
- heart valve defects,
- movement anomalies of the ventricular walls,
- Pericarditis
- congenital heart defects.
4. Transesophageal echocardiography
This examination can be used to show:
- dysfunction of the heart valves,
- contractile defects of the heart.
Laboratory tests
The blood test is also done to check BNP (B-natriuretic peptide) levels. An increased level of this peptide may indicate that pulmonary edema was caused by cardiac problems. Other blood tests that are usually done are:
- studies of kidney function,
- Blood count
- Blood gas analysis.
Other medically recommended examinations are:
- Cardiac catheterization. With this invasive examination, the heart cavities and large blood vessels of the heart can be examined.
- Catheter examination of the pulmonary artery. This is an invasive examination to detect:
- pressure of the lungs and right atrium,
- Oxygen saturation of the blood.
Differential diagnosis
The doctor must rule out other common causes of severe breathing difficulties, such as:
- bronchial asthma,
- Pneumonia
- Chronic obstructive pulmonary disease (COPD),
- Pulmonary emphysema
- Pulmonary embolism.
Treatment of pulmonary edema and drugs
Oxygen therapy is the first step in the treatment of this condition.
The administration of oxygen takes place via:
- face mask or
- Nasal tube (a plastic tube with two openings that administer oxygen through both nostrils).
Sometimes it is necessary to support breathing mechanically (asuspended spontaneous breathing).
Medicines for pulmonary edema
Medication to reduce the pressure preload. These drugs reduce the pressure caused by the fluid entering the heart and lungs. Doctors prescribe for the treatment of pulmonary edema:
- Nitroglycerin
- Diuretics, for example, furosemide (Lasix).
The diuretics lead to abundant urination to eliminate the excess fluid.
Insertion of a urinary catheter may be necessary during hospitalization.
Morphine (MSI). This narcotic alleviates:
- Shortness of breath
- Anxiety and fear of suffocation.
Some doctors believe that the risks of morphine outweigh the benefits and that there are other more effective drugs, such as naloxone.
Medications for increased afterload. These drugs dilate blood vessels and reduce pressure in the left ventricle of the heart.
Some examples of pressure reduction of the afterload are:
- nitroprusside (sodium nitroprusside),
- Enalapril.
Blood pressure medications. With high blood pressure and when pulmonary edema develops, the doctor prescribes lowering drugs.
On the other hand, if blood pressure is too low, the doctor recommends medication that raises the pressure.
Pulmonary edema at high altitudes
At high altitudes (from 2500 m) the oxygen content in the air decreases.
This circumstance can cause pulmonary edema.
The first symptoms of high-altitude pulmonary edema are:
- Indisposition
- Headache
- Anorexia
- nausea or vomiting,
- Vertigo
- Fatigue and weakness.
When symptoms of mild pulmonary edema appear, it is necessary to descend very quickly a few hundred meters (from 600 to 900 meters) to relieve the symptoms.
In this case, the administration of oxygen is necessary.
If the symptoms are more serious, it is necessary to descend with the help of rescue workers.
Emergency medical treatment is necessary to prevent:
- serious complications,
- death.
Some climbers take the prescription drug acetazolamide (Diamox), which is used to prevent symptoms of high-altitude pulmonary edema.
It is important to take this medication three days before the ascent.
Side effects of acetazolamide include:
- ants tingling in the hands,
- burning sensation on the skin of hands and feet,
- mental confusion,
- Diarrhea
- Nausea
- loss of appetite,
- temporary hearing loss.
How long does acute pulmonary edema last? Is it possible to get well? Prognosis
Hospital mortality rates are difficult to calculate for patients with cardiac pulmonary edema because the cause and severity of the disease vary widely.
Death occurs in 15-20% of patients admitted in acute phase.
