Acute Respiratory failure
Respiratory failure is defined as respiratory dysfunction resulting in abnormalities of oxygenation or ventilation (CO2 elimination) severe enough to threaten the function of vital organs. Arterial blood gas criteria for respiratory failure are not absolute but may be arbitrarily established as a Po2 under 60 mm Hg (7.8 kPa) or a Pco2 over 50 mm Hg (6.5 kPa). Acute respiratory failure may occur in a variety of pulmonary and nonpulmonary disorders.
Respiratory failure is classified according to blood gases abnormalities into type 1 and type 2.
Type 1 – (hypoxemic) respiratory failure has a PaO2 < 60 mmHg with normal or subnormal PaCO2. In this type, the gas exchange is impaired at the level of aveolo-capillary membrane. Examples of type I respiratory failures are carcinogenic or non-cardiogenic pulmonary edema, ARDs, COVID-19 and severe pneumonia.
This lung damage prevents adequate oxygenation of the blood (hypoxaemia); however, the remaining normal lung is still sufficient to excrete the carbon dioxide being produced by tissue metabolism. This is possible because less functioning lung tissue is required for carbon dioxide excretion than is needed for oxygenation of the blood.
Type 2 – (hypercapnic) respiratory failure has a PaCO2 > 50 mmHg. Type II respiratory failure involves low oxygen, with high carbon dioxide (pump failure). It occurs when alveolar ventilation is insufficient to excrete the carbon dioxide being produced. The most common cause is chronic obstructive pulmonary disease (COPD).
Others include chest-wall deformities, respiratory muscle weakness (e.g. Guillain-Barre syndrome) and central depression of the respiratory centre (e.g. heroin overdose) Inadequate ventilation is due to reduced ventilatory effort, or inability to overcome increased resistance to ventilation – it affects the lung as a whole, and thus carbon dioxide accumulates. Complications include: damage to vital organs due to hypoxaemia, CNS depression due to increased carbon dioxide levels, respiratory acidosis (carbon dioxide retention). This is ultimately fatal unless treated.
Signs and symptoms
Symptoms and signs of acute respiratory failure are those of the underlying disease combined with those of hypoxemia or hypercapnia.
The chief symptom of hypoxemia is dyspnea, though profound hypoxemia may exist in the absence of complaints.
Signs of hypoxemia include cyanosis, restlessness, confusion, anxiety, delirium, tachypnea, bradycardia or tachycardia, hypertension, cardiac dysrhythmias, and tremor. Dyspnea and headache are the cardinal symptoms of hypercapnia.
Signs of hypercapnia include peripheral and conjunctival hyperemia, hypertension, tachycardia, tachypnea, impaired consciousness, papilledema, and asterixis.
The symptoms and signs of acute respiratory failure are both insensitive and nonspecific; therefore, the clinician must maintain a high index of suspicion and obtain arterial blood gas analysis if respiratory failure is suspected.
Treatment for respiratory failure depends on
- Whether it is acute (short-term) or chronic (ongoing)
- How severe it is
- What is causing it
Acute respiratory failure can be a medical emergency. You may need treatment in intensive care unit at a hospital. Chronic respiratory failure can often be treated at home. But if your chronic respiratory failure is severe, you might need treatment in a long-term care center.
One of the main goals of treatment is to get oxygen to your lungs and other organs and remove carbon dioxide from your body. Another goal is to treat the cause of the condition. Treatments may include
- Oxygen therapy, through a nasal cannula (two small plastic tubes that go in your nostrils) or through a mask that fits over your nose and mouth
- Tracheostomy, a surgically-made hole that goes through the front of your neck and into your windpipe. A breathing tube, also called a tracheostomy, or trach tube, is placed in the hole to help you breathe.
- Ventilator, a breathing machine that blows air into your lungs. It also carries carbon dioxide out of your lungs.
- Other breathing treatments, such as noninvasive positive pressure ventilation (NPPV), which uses mild air pressure to keep your airways open while you sleep. Another treatment is a special bed that rocks back and forth, to help you breathe in and out.
- Fluids, often through an intravenous (IV), to improve blood flow throughout your body. They also provide nutrition.
- Medicines for discomfort
- Treatments for the cause of the respiratory failure. These treatments may include medicines and procedures.
If you have respiratory failure, see your health care provider for ongoing medical care. Your provider may suggest pulmonary rehabilitation.
If your respiratory failure is chronic, make sure that you know when and where to get help for your symptoms. You need emergency care if you have severe symptoms, such as trouble catching your breath or talking. You should call your provider if you notice that your symptoms are worsening or if you have new signs and symptoms.
Living with respiratory failure may cause fear, anxiety, depression, and stress. Talk therapy, medicines, and support groups can help you feel better.