Acute respiratory failure: diagnosis and emergency treatment

2021-08-03 12:11 AM

Respiratory failure occurs when the small blood vessels, which surround the alveolar sacs are unable to exchange gases, experience immediate symptoms, due to insufficient oxygen in the body

Acute respiratory failure

Acute respiratory failure can be seen in the emergency and inpatient departments, as well as in the postoperative and intensive care units. If left untreated, acute respiratory failure can become life-threatening leading to respiratory arrest, convulsions, coma, and death.

Respiratory failure occurs when the capillaries, or small blood vessels, that surround the alveolar sacs are unable to exchange gases. In acute respiratory failure, immediate symptoms are experienced because there is not enough oxygen in the body. In most cases, it can lead to death if not treated quickly.

Acute respiratory failure is a medical emergency that occurs when the respiratory system is unable to meet the body's metabolic needs.

There are 3 types of respiratory failure: hypoxemia, increased CO 2 blood and mixed.

Hypoxemia when PaO 2 < 50-60 mmHg.

Increased CO 2 blood when Paco 2 > 50mmHg with acidosis, blood pH <7.36.

Can mix the blood had decreased oxidation and increase CO 2 blood are common types of respiratory failure in critically ill patients.

Acute respiratory failure may occur in a patient without pre-existing lung disease or in a patient with chronic respiratory failure.

Diagnosis of acute respiratory failure

Shortness of breath

It is an important and sensitive signal.

Shortness of breath fast (> 25 breaths/min) or slow (< 12 breaths/minute) or arrhythmia (Kussmaul, Cheyne - Stokes... ), shallow or deep breathing amplitude.


Occurs when reduced Hb > 5g/dl, is a sign of severe respiratory failure.

Early: purple around lips, lips, extremities.

Severe, late: purple spreading to the whole body.

No cyanosis or late onset of cyanosis in CO poisoning.


Cardiovascular disorders

Rapid pulse, possibly arrhythmia (atrial fibrillation, supraventricular tachycardia, ventricular fibrillation...).

High blood pressure, if severe, can drop blood pressure.

Often combined symptoms of respiratory failure and circulatory failure. In fact, it is important to distinguish whether the respiratory failure is a cause or a consequence.

Nervous and Consciousness Disorders

Severe symptoms of respiratory failure.

Mild: anxiety, panic, ataxia.

Severe: lethargy or somnolence, lethargy, coma, convulsions.


Clinical signs and symptoms may appear only in the presence of severe respiratory failure, in the presence of severe and dangerous disturbances of gas exchange. Symptoms tachypnea, tachycardia, hypertension can occur when stars 2 fell very low <70-80%. Cyanosis may be present only when PaO 2 < 45 mmHg, especially when the patient is anemic.

Clinical signs and symptoms of respiratory failure are nonspecific and may also be present in the absence of respiratory failure.

Level diagnosis

Table of Classification of respiratory failure

Diagnostic of the cause of respiratory failure

Diagnostic orientation

Ask about medical history: bronchial asthma, COPD, cardiovascular disease...

Clinical features

Contraction of respiratory muscles: stridor, laryngeal dyspnea, rales, bronchospasm

Breathing amplitude is weak (myasthenia gravis, muscle fatigue), strong (metabolic acidosis).

How to appear:

+ Sudden: foreign body, cyst, pneumothorax.

+ Fast: OAP, bronchial asthma, pneumonia...

+ Slowly: lung tumor, pleural effusion, decompensated heart failure...

Chest pain: pneumothorax, pulmonary infarction, pleurisy, myocardial infarction.

Fever (infection): pneumonia, bronchitis...


Careful examination of the respiratory, cardiovascular, and neurological conditions is required.

A thorough examination of the lungs

+ Ran wet, raspy.

+ Syndrome 3 hypo concentration, the triad of pneumothorax.

Cardiovascular examination

Signs and symptoms of heart failure, heart disease...

Neurological examination

Awareness, symptoms of respiratory muscle paralysis...

Basic tests

Chest X-ray: very important in orienting the diagnosis. However, it is necessary to stabilize the patient's condition before taking the patient for imaging. Many diseases have symptoms on chest X-rays.

However, there are a number of conditions that often have no obvious radiographic symptoms: pulmonary infarction, bronchial asthma, upper airway obstruction, respiratory depression or respiratory paralysis.

Arterial blood gases: essential for the definitive diagnosis of respiratory failure, classification of respiratory failure, and assessment of the severity of the respiratory failure. However, the use of arterial blood gas testing should not delay interventions and emergency management of patients.

Electrocardiogram: helps diagnose some heart diseases and find electrocardiographic signs of lung disease, arrhythmias due to respiratory failure...

Are other tests allowed depending on the specific case and the severity of the patient's condition?


Pulmonary scintigraphy.

Lung CT scan.

D-dimer quantification.

Common causes of respiratory failure

Airway foreign body: usually appears suddenly with symptoms of infiltration, dyspnea, stridor, contracture and use of accessory respiratory muscles. Severe obstruction can cause consciousness disturbances, respiratory arrest, and cardiac arrest.

Pneumothorax: shortness of breath that comes on suddenly after exertion or spontaneously. If there is vascular collapse, consider tension pneumothorax. On physical examination, one side of the chest may be distended, with reduced alveolar murmurs and resonant percussion, requiring gradual management of emergency ventilation, especially when the pneumothorax is present.

Acute exacerbation of chronic obstructive pulmonary disease (COPD) is characterized by increased secretion of purulent sputum and bronchospasm. Characteristics of mixed respiratory failure with both hypoxemia and elevated C02. Diagnosis is based on the patient's history with a history of chronic obstructive pulmonary disease, the appearance of shortness of breath, increased cough with sputum, cloudy sputum, possibly fever. Examination may reveal rales, snoring, emphysema, and use of accessory muscles of respiration.

Pneumonia usually takes the form of respiratory failure due to hypoxemia. Diagnosis is based on clinical patients with fever, cough with cloudy sputum, dyspnea, pleuritic chest pain. Pulmonary examination showed consolidation syndrome in the inflammatory lung area, moist rales, crackles, and tube murmurs. Blood tests may show elevated white blood cells, elevated CRP, elevated procalcitonin, and elevated erythrocyte sedimentation rate. Chest radiographs confirm the diagnosis, assess severity, and help monitor progression.

Advanced respiratory distress syndrome (ARDS) is the manifestation of a systemic inflammatory response due to lung injury or extrapulmonary causes. Severe hypoxic respiratory failure is the result of increased shunt due to alveolar filling. Clinically, rapidly progressive respiratory failure, hypoxia (P/F < 200). Chest X-ray showed diffuse lesions on both sides of the lungs.

Traumatic brain injury often presents with respiratory failure have increased CO 2 blood, can be complicated by respiratory failure with hypoxemia when accompanied choke chronic lung or lung disease.

Decompensated congestive heart failure: mainly hypoxemic respiratory failure but may have to increase the CO 2 in patients with chronic lung disease attached.

Treatment of acute respiratory failure

Principles of emergency treatment

Immediately detect critical respiratory failure to intervene in the sequence of the ABCD emergency chain, administer medication, monitor, and control the patient's vital function well.

Open the airways

Protruding neck (postural drainage).

Canun Guedel or Mayo against tongue drop.

Suction sputum, suction bronchial lavage.

The side position is safe if there is a risk of choking.

The Heimlich maneuver if an airway foreign body is present.

Endotracheal (or tracheostomy): an effective means of opening the airway.

Indications for endotracheal intubation

Upper airway obstruction.

Loss of protective airway reflexes.

The ability to produce sputum is greatly reduced or lost.

Severe hypoxia is unresponsive to oxygen.

Requires invasive artificial ventilation.

Ventilation control: cases requiring ventilatory support.

Hypoventilation: Respiratory acidosis with pH < 7.25.

There is a risk that hypoventilation or hypoventilation will worsen: PaC02 gradually increases.

Rapid breathing and feeling of lack of air.

Paralysis or muscle fatigue (paradoxical abdominal breathing, vital capacity < 15ml/kg, maximal inspiratory pressure not achieved - 30cm of water).

Severe hypoxia responds poorly to oxygen breathing.

Oxygen therapy

Principles: to ensure blood oxidation SPO 2 > 90%.

Breathing devices.

+ Nasal canun: is a device with a low oxygen flow of 1 - 5l/min. Oxygen concentrations ranged from 24%-48%. Suitable for patients with moderate respiratory failure, patients with COPD, or other causes of respiratory failure without shunts or low intrapulmonary shunts.

+ Oxygen mask: is a low-current generator 5-101/min. Oxygen concentration ranges from 35% to 60%. Suitable for patients with moderate respiratory failure due to damage to the alveolar-capillary membrane (ALI, ARDS).

Use caution in patients with vomiting due to the increased risk of aspiration of vomit into the lungs.

+ non-rebreathing mask: is a low-oxygen flow device of 8-151/min. High oxygen concentrations range as high as 60%-100% depending on the patient's flow needs and mask tightness. Suitable for patients with severe respiratory failure due to damage to the alveolar-capillary membrane (pulmonary edema, ALI, ARDS), patients with severe pneumonia. Use caution in patients with vomiting due to the increased risk of aspiration of vomit into the lungs.

+ Venturi mask: is a high-flow oxygen generator that can meet the needs of the patient's current.

Oxygen concentration ranges from 24% to 50%. The advantage is for patients who need precise oxygen levels (COPD).

Artificial ventilation

Positive pressure non-invasive artificial ventilation: support ventilation for the patient through a mask (nose, nose, mouth, whole face...).


Respiratory failure due to hemodynamic acute pulmonary edema, exacerbation of COPD, and bronchial asthma when:

Severe respiratory failure with signs of muscle fatigue: labored breathing + respiratory rate > 30/min.

Acute respiratory acidosis (pH < 7.25-7.30).

The oxygenation of the blood worsened (ratio of PaO 2 / FiO 2  < 200).


Stop breathing.

Unstable medical condition (uncontrolled hypotension or myocardial ischemia).

Loss of airway protection.

Excessive phlegm.

Struggling or not cooperating.

The patient's condition does not allow the mask to be placed or the mask's tightness is not guaranteed.

Invasive ventilation: when non-invasive ventilation is contraindicated or has failed.

Drug treatment

Bronchodilators (agonists (32; anticholinergics): indicated for respiratory failure due to bronchospasm (COPD, bronchial asthma) Should be given by nebulizer first if no response then bronchodilator switch to intravenous infusion.

Corticosteroids: indicated for exacerbations of bronchial asthma, COPD.

Antibiotics: when there are signs of inflammation (pneumonia, exacerbation of COPD with evidence of infection).

Diuretics: congestive heart failure, hemodynamic acute pulmonary edema, volume overload.

Related articles:

Respiratory failure

Types of acute respiratory failure

What is acute respiratory failure (ARF)?