OVERVIEW

What is respiratory failure?

When the body lacks sufficient oxygen or has excessive carbon dioxide reaching certain levels, it can be termed respiratory failure.

It is a clinical syndrome caused by severe impairment of lung ventilation and/or gas exchange due to various factors, leading to ineffective gas exchange. This results in hypoxia (with or without) carbon dioxide retention, triggering a series of physiological and metabolic disorders.

What people often describe as "breathing is failing" or "almost out of breath" may frequently indicate respiratory failure. However, many other factors, such as emotional stress or heart attacks, can also present similar symptoms, which may not necessarily be true respiratory failure upon examination.

Additionally, patients with "chronic bronchitis" (medically termed chronic obstructive pulmonary disease) may exhibit signs of respiratory failure, along with symptoms like abnormal mental excitement or even mania, gradually progressing to unconsciousness.

What is respiration?

Simply put, respiration is the process where the body inhales oxygen and exhales carbon dioxide, facilitating gas exchange between the body and the external environment.

The human respiratory process consists of three interconnected stages:

• External respiration, including pulmonary ventilation and gas exchange in the lungs;
• Transport of gases in the blood;
• Internal respiration, referring to gas exchange between tissue cells and blood.

How is respiration determined?

One inhalation plus one exhalation constitutes one breath, marked by a rise and fall of the chest or abdomen. Breathing primarily manifested by chest movement is called thoracic respiration, while that by abdominal movement is called abdominal respiration—both are normal forms. Additionally, placing a cotton thread (to observe movement) or a mirror (to check for fogging) near the mouth or nose can help detect airflow.

What organs make up the human respiratory system?

The human respiratory system mainly consists of the nose, pharynx, larynx, trachea, bronchi, and lungs. Apart from the nose, disorders or blockages in any of these parts may lead to respiratory failure.

Why is oxygen so vital to the human body?

For any cell in the body to survive, it requires nutrients and must undergo metabolism. Oxygen is essential for metabolic processes; otherwise, normal physiological functions cannot be sustained.

SYMPTOMS

What are the general manifestations of respiratory failure patients?

In addition to the symptoms of the primary disease, the following symptoms may occur:

• Respiratory system: Dyspnea, tachypnea, chest tightness, etc.

• Cardiovascular system: Increased heart rate, arrhythmia, ventricular fibrillation, cardiac arrest, etc.

• Nervous system: Headache, dizziness, restlessness, confusion, drowsiness, convulsions, coma, etc.

• Digestive system: Loss of appetite, gastric ulcers, upper gastrointestinal bleeding, etc.

• Others: Cyanosis of the lips, conjunctival congestion, edema, etc.

What is pulmonary encephalopathy?

It refers to a condition where patients without underlying neurological diseases develop severe hypoxia and/or carbon dioxide retention due to various causes, leading to severe hypoxemia and hypercapnia, which in turn result in neuropsychiatric abnormalities. This often occurs during the exacerbation of chronic obstructive pulmonary disease (COPD).

What are the manifestations of pulmonary encephalopathy in COPD patients?

Initially, patients may experience sleep reversal, such as daytime sleepiness and nighttime insomnia, with headaches in the morning due to nocturnal carbon dioxide retention. Neuropsychiatric symptoms may include mental confusion, apathy, drowsiness, stupor, or varying degrees of coma, as well as excitement, talkativeness, restlessness, convulsions, etc.

Does respiratory failure always cause a persistent feeling of dyspnea and breathlessness?

Respiratory failure is not synonymous with dyspnea. Diagnosis requires relevant medical examinations. Moreover, many diseases can cause dyspnea, so differential diagnosis is essential to avoid delaying treatment.

What are the classifications of respiratory failure?

Patients diagnosed with respiratory failure exhibit hypoxemia when not receiving oxygen therapy. If there is no retention of waste gas (carbon dioxide), it is classified as Type I respiratory failure; if waste gas cannot be expelled, it is classified as Type II respiratory failure.

Based on the speed of onset, respiratory failure can be divided into acute and chronic respiratory failure. Acute respiratory failure occurs suddenly due to conditions such as airway disorders, lung tissue diseases, pulmonary vascular diseases, thoracic abnormalities, or neuromuscular disorders. Chronic respiratory failure typically occurs in patients with chronic respiratory diseases, such as chronic obstructive pulmonary disease or severe tuberculosis.

What are the damages of respiratory failure to other organs in the body?

Respiratory failure primarily harms various organs due to hypoxia and carbon dioxide retention toxicity, manifesting in the following aspects:

• Effects on the brain: Headache, excitement, restlessness, drowsiness, coma, convulsions, etc.

• Effects on the cardiovascular system: Palpitations, chest tightness, arrhythmias, cardiac arrest, etc.

• Others: Elevated liver enzymes, increased serum creatinine, gastrointestinal bleeding, reduced urine output, anuria, water-electrolyte and acid-base imbalances, and even death.

CAUSES

Who is prone to respiratory failure?

• Since the lungs are connected to the external atmosphere, they are vulnerable to attacks from various pathogens and harmful substances. However, there is no need to worry excessively, as the normal body has defense mechanisms that can effectively clear pathogens and harmful substances.

• However, newborns, elderly patients, smokers, cancer patients, diabetics, AIDS patients, those taking immunosuppressive drugs, malnourished individuals, long-term bedridden patients, and those with chest deformities have weakened abilities to clear respiratory pathogens and harmful substances. Their lungs are more susceptible to damage, making them high-risk groups for respiratory failure. Additionally, patients with conditions such as chronic obstructive pulmonary disease (COPD), bronchiectasis, severe tuberculosis (lung destruction), etc., have deformed lung structures and impaired ventilation function. Even a common cold or difficulty coughing up phlegm can trigger respiratory failure, which warrants attention.

In which season is respiratory failure more likely to occur?

• During cold seasons and seasonal transitions, the likelihood of respiratory infections increases. Temperature fluctuations can also cause airway constriction, potentially triggering asthma or respiratory failure. Asthma patients should be particularly cautious during "pollen season," as they may experience sudden asthma attacks or respiratory failure due to pollen allergies.

What diseases can lead to respiratory failure?

Respiratory failure can be classified into acute and chronic based on its course, each with different causes.

• Main causes of acute respiratory failure:

  • Respiratory diseases: Acute respiratory distress syndrome (ARDS), acute pneumonia, airway obstruction, pulmonary embolism, severe pneumothorax, chest trauma, etc.;
  • Cardiovascular diseases: Acute cardiogenic pulmonary edema (acute left heart failure), cardiac arrest, acute myocardial infarction, myocarditis, etc.;
  • Neuromuscular diseases: Cerebrovascular diseases, head trauma, encephalitis, poisoning, drug overdose, etc.

• Main causes of chronic respiratory failure:

  • Respiratory diseases: Chronic obstructive pulmonary disease (COPD), severe tuberculosis, bronchiectasis, diffuse pulmonary interstitial fibrosis, pneumoconiosis, chest deformities, etc.;
  • Cardiovascular diseases: Pulmonary arterial hypertension, cardiomyopathy;
  • Neuromuscular diseases: Spinal cord injuries, polyneuritis, myasthenia gravis, etc.

DIAGNOSIS

What are the criteria for diagnosing respiratory failure?

At sea level under resting conditions while breathing room air, and after excluding intracardiac anatomical shunts and primary reductions in cardiac output, an arterial oxygen partial pressure (PaO₂) below 8 kPa (60 mmHg), or accompanied by a carbon dioxide partial pressure (PaCO₂) above 6.65 kPa (50 mmHg), indicates respiratory failure.

What are acute and chronic respiratory failure?

• Acute respiratory failure often occurs in patients with previously normal lung function, caused by acute lung or other organ diseases. For example, severe pancreatitis can lead to the accumulation of inflammatory substances in the lungs through circulation, damaging them and causing acute respiratory failure. Another example: the brain is the "high command" controlling respiration. If the respiratory control center is affected (e.g., by a stroke), it can suppress respiratory function, leading to acute respiratory failure. Certain lung diseases, such as severe pneumonia, can also cause acute respiratory failure.

• Chronic respiratory failure is more common in patients with chronic respiratory diseases, such as COPD, severe tuberculosis, or bronchiectasis. These patients often experience worsening lung function due to respiratory infections (e.g., colds, bronchitis, pneumonia), leading to respiratory failure. Their lung function deteriorates gradually, and the body may partially adapt to hypoxia and hypercapnia. Their symptoms are milder than those with acute respiratory failure, but they are more likely to delay treatment due to underestimating their condition.

What is a "blood gas" test for respiratory failure patients?

Here, "blood gas" refers to arterial blood gas analysis, a technical process that measures oxygen and carbon dioxide levels and acid-base balance in arterial blood.

It is the most important diagnostic test for respiratory failure, helping to distinguish between types of respiratory failure and assess its severity and acid-base imbalance.

What tests are generally performed for respiratory failure patients?

Routine tests include blood gas analysis, electrolyte tests, sputum tests, and, if the patient's condition allows, pulmonary function tests and chest imaging.

• Blood gas analysis: At sea level under resting conditions while breathing room air (or adjusted for oxygen therapy), if arterial oxygen partial pressure (PaO₂) is below 8 kPa (60 mmHg) without elevated carbon dioxide partial pressure (PaCO₂) above 6.65 kPa (50 mmHg), it is classified as Type I respiratory failure. If PaO₂ is below 8 kPa (60 mmHg) with PaCO₂ above 6.65 kPa (50 mmHg), it is Type II respiratory failure.

• Electrolyte tests: Respiratory acidosis combined with metabolic acidosis often involves hyperkalemia, while respiratory acidosis with metabolic alkalosis may show hypokalemia and hypochloremia.

• Sputum smear and bacterial culture: These provide crucial information for further treatment.

• Pulmonary function tests and chest imaging: Key diagnostic methods for underlying diseases, guiding subsequent treatment plans.

How is the cause of respiratory failure differentiated?

Respiratory failure presents with diverse symptoms, and the causes vary. Differential diagnosis includes:

• If a tall, thin young adult experiences sudden chest pain followed by dyspnea, consider pneumothorax-induced respiratory failure.

• If respiratory failure is accompanied by hemoptysis, pulmonary embolism should be suspected.

• Nocturnal paroxysmal orthopnea (patients forced to sit or recline to relieve dyspnea) suggests left heart failure or bronchial asthma.

• Sudden inspiratory dyspnea may indicate airway obstruction by a foreign body.

• Chronic progressive respiratory failure is common in COPD and diffuse pulmonary fibrosis patients.

Definitive diagnosis requires a comprehensive assessment of the patient's history, symptoms, signs, and diagnostic tests.

TREATMENT

Is respiratory failure untreatable?

No.

Acute respiratory failure can fully recover with timely and appropriate treatment. A significant portion of chronic respiratory failure patients can overcome critical conditions with active intervention. After stabilization, as long as respiratory infections and other triggers are prevented or promptly managed, and lung function deterioration is delayed as much as possible, most patients can maintain a relatively good quality of life. Patients and their families should strengthen confidence in treatment and actively cooperate with medical professionals.

Which department should respiratory failure patients visit in the hospital?

If the cause is unclear and vital signs are unstable, patients should go to the emergency department to stabilize their condition and preliminarily identify the cause. If the condition permits, they should visit the respiratory medicine department and, if necessary, be transferred to the intensive care unit (ICU) for respiratory-related conditions.

Additionally, if the cause of respiratory failure is already known, patients should visit the corresponding specialized department.

How should respiratory failure patients be treated and cared for?

• First, actively treat the underlying disease, eliminate triggers, and manage infections. Keep the airways clear by administering bronchodilators and expectorants.

• Patients capable of coughing should be encouraged to expel phlegm. Elderly patients should be assisted with regular turning and back patting to promote sputum discharge. If coughing does not significantly affect daily life or sleep, excessive cough suppression should be avoided to prevent the risk of mucus obstruction.

• Correct hypoxia by using nasal cannulas or oxygen masks.

• For severe hypoxia and/or carbon dioxide retention with significant consciousness impairment (e.g., pulmonary encephalopathy), mechanical ventilation should be initiated promptly.

Is higher oxygen concentration better for correcting hypoxia in respiratory failure patients?

No.

For chronic respiratory failure patients (e.g., chronic bronchitis, COPD), controlled low-concentration oxygen therapy is recommended (oxygen flow rate typically 1–2 L/min).

High-flow oxygen can worsen carbon dioxide retention in COPD patients, leading to pulmonary encephalopathy, deterioration, or even life-threatening risks.

Can respiratory failure be treated without hospitalization?

It depends on the condition. After hospitalization, some chronic patients may achieve normal indicators and can be managed as outpatients or even at home with oxygen therapy and active treatment of the underlying disease. Severe cases should be hospitalized.

How is pulmonary encephalopathy caused by respiratory failure treated?

Since the root causes are hypoxia and carbon dioxide toxicity, treatment focuses on oxygen therapy to improve hypoxia and promote CO2 elimination.

• Nasal cannulas or oxygen masks can alleviate hypoxia.

• Severe cases require mechanical ventilation. Ventilators act as air pumps, assisting breathing to enhance oxygen intake and CO2 expulsion.

• Airway spasms and mucus blockage also worsen pulmonary encephalopathy, so bronchodilators and expectorants should be used to relieve obstruction and improve ventilation.

Can morphine be used for respiratory failure patients?

Generally, no. Morphine suppresses respiration, worsening respiratory failure and potentially causing fatal respiratory paralysis.

However, if the patient is already on mechanical ventilation (which replaces spontaneous breathing) and requires sedation without contraindications, cautious use may be considered.

DIET & LIFESTYLE

For patients with respiratory failure caused by COPD, doctors recommend long-term home oxygen therapy. How many hours per day should it be used? Can they use it occasionally for short periods?

Absolutely not.

Low-flow oxygen therapy should be administered for more than 15 hours per day. Occasional use will not achieve therapeutic effects. Long-term adherence not only alleviates symptoms but also slows disease progression.

For respiratory failure patients who have purchased a home oxygen concentrator, what precautions should be taken during use?

Before oxygen therapy, clean the patient’s nostrils with a cotton swab dipped in water. Read the instruction manual carefully before first use. Pay attention to oxygen safety, and regularly disinfect nasal cannulas, masks, humidifier bottles, etc.

What dietary precautions should respiratory failure patients take?

During the acute phase, nasogastric feeding or liquid diets are recommended. As the condition stabilizes, transition gradually to semi-liquid or soft foods. After recovery, acute respiratory failure patients can consume regular or semi-liquid diets such as steamed eggs, minced meat noodles, or wontons.

Dietary adjustments for respiratory failure patients depend on their condition. For example, those with type II respiratory failure should reduce carbohydrate intake and increase fat intake for energy.

Can respiratory failure patients promote recovery through increased exercise?

During the acute phase, absolute bed rest is necessary, with limb movements and frequent repositioning to prevent skin damage, ensuring adequate sleep. During the remission phase, patients can sit up and move around the bed, gradually increasing activity levels without rushing.

How exactly is the "breathing exercise" performed for chronic respiratory failure patients during recovery?

The specific method is: inhale through the nose with the mouth closed, then purse the lips to exhale slowly.

It resembles deep breathing but focuses on prolonging exhalation—inhaling and exhaling slowly.

If the breathing rate is too fast, incomplete inhalation makes it ineffective.

Breathing exercises can be practiced during household chores or while sitting quietly, 10–15 minutes daily. Consistent practice yields noticeable results over time.

What should chronic respiratory failure patients pay attention to after discharge?

Chronic respiratory failure patients should continue home oxygen therapy, follow prescribed medications, prevent and promptly address respiratory infections, and avoid smoking, alcohol, and irritating foods. Schedule regular specialist follow-ups and seek immediate medical attention if symptoms like shortness of breath or cyanosis occur.

PREVENTION

How to prevent respiratory failure?

• Actively treat and control underlying primary diseases, relieve bronchospasm, reduce bronchial secretions, decrease airway resistance, and minimize energy consumption.

• Improve the body's nutritional status, persist in feasible exercises, perform breathing exercises daily to enhance respiratory muscle function.

• For elderly patients or those with chronic obstructive pulmonary disease and poor resistance, regular vaccination against pneumococcus and other pathogens can prevent infections.