Elderly respiratory failure

Introduction to respiratory failure in the elderly Respiratory failure (respiratory failure) is not a disease, but is caused by various causes of severe damage to lung function, causing hypoxia or carbon dioxide retention, which leads to a series of clinical dysfunction and metabolic disorders of the body, as well as breathing Failure has no obvious clinical features in the early stage, so it is generally necessary to make a clear diagnosis through laboratory arterial blood gas analysis. basic knowledge The proportion of illness: 0.005%--0.01% Susceptible people: the elderly Mode of infection: non-infectious Complications: gastrointestinal bleeding, shock, heart failure, respiratory failure, pulmonary edema

Causes of respiratory failure in the elderly

Respiratory lesions (20%):

Involvement of upper and lower respiratory tract diseases, as long as causing obstruction, resulting in inadequate ventilation and uneven gas distribution, resulting in ventilated blood flow imbalance can cause respiratory failure, such as laryngeal edema, bronchospasm caused by various causes, respiratory tract Secretion of secretions or foreign bodies.

Lesions of the lung tissue (20%):

There are many causes of diffuse pulmonary parenchymal lesions, the most common such as various pneumonia, severe tuberculosis, emphysema, diffuse pulmonary fibrosis, silicon deposition; pulmonary edema caused by various causes, atelectasis Etc., causing lung ventilation, effective area reduction, imbalance between ventilation and blood flow, right-to-left shunt in the lung, and hypoxia.

Pulmonary vascular disease (20%):

Pulmonary embolism, fat embolism, pulmonary vasculitis, multiple microthrombus formation, impaired lung ventilation, leading to hypoxia.

Thoracic lesions (5%):

Including chest wall and pleural disease, severe thoracic deformity, thoracic trauma, pulmonary contusion, surgical trauma, massive pneumothorax or pleural effusion, pleural thickening, spontaneous or traumatic pneumothorax affecting thoracic activity and lung expansion, resulting in reduced ventilation and The distribution of the inhaled gas is uneven, which affects the ventilation function.

Neuromuscular lesions (5%):

The lungs of these patients are often completely normal. The primary disease mainly involves the brain, nerve pathway or respiratory muscle, which directly or indirectly inhibits the respiratory center; the nerve-muscle joint block affects the conduction function; the respiratory muscle has no strength for normal ventilation, which is common in Cerebrovascular disease, encephalitis, brain trauma, electric shock, drug poisoning, polio and polyneuritis, myasthenia gravis.

Pathogenesis

Human respiratory activity can be divided into four functional processes, namely ventilation, diffusion, perfusion, and respiratory regulation. Each of these processes plays an important role in maintaining normal arterial blood PO2 and PCO2 levels, and any process is abnormal and equivalent. Severe, it will lead to respiratory failure, and there are several abnormalities in the clinically common respiratory diseases.

Insufficient ventilation

Ventilation refers to the movement of air from the outside to the body and through the trachea and bronchial system to the lung gas exchange unit, which refers to the process of air reaching the alveoli. When PaCO2 is elevated, there is insufficient alveolar ventilation. At this time, the patient only inhales O2. Higher concentration of gas, otherwise PaO2 will decrease with the increase of PaCO2. When the ventilation is insufficient, the direction of change of PaO2 and PaCO2 is opposite, but the quantity is basically the same, so it can be easily judged that the hypoventilation is insufficient in the patient hypoxemia. Occupational status, arterial hypoxemia caused by insufficient alveolar ventilation is not accompanied by an increase in the PaO2 difference in alveolar arterial blood, so the absorption of pure oxygen can be corrected. Conversely, if it cannot be corrected, there are other reasons. .

2. Dispersion barrier

Dissemination refers to the movement of O2 and CO2 across the alveolar capillary wall between the gas in the alveolar space and the blood in the pulmonary capillaries, that is, the gas exchange process.

The CO2 diffusion ability is 20 times higher than O2. If the non-dispersion function is extremely severe, it will not lead to arterial hypercapnia in a quiet state, and the diffuse area is reduced (such as pulmonary parenchymal lesions, emphysema, atelectasis, etc.) and diffuse film. Thickening (such as pulmonary interstitial fibrosis, pulmonary edema, etc.) can cause simple hypoxia.

3. Ventilation - perfusion imbalance

If the gas exchange unit receives more blood than ventilation, it will produce arterial blood hypoxemia, which is the most common cause of arterial hypoxemia and can be made low by inhaling 100% oxygen to the patient. Oxygenemia has improved, and it has been confirmed that such patients have little CO2 retention.

4. Right to left shunt

The right-to-left shunt of blood can occur in abnormal anatomical passages in the lungs, such as pulmonary arteriovenous fistulas, but more in alveolar collapse (lung atelectasis) or alveolar spaces filled with fluids such as pulmonary edema, pneumonia or alveolar hemorrhage. Etc., causing physiological diversion and causing hypoxemia, such patients do not have CO2 retention.

5. Hypercapnia

Arterial hypercapnia can be said to be caused by a significant decrease in alveolar ventilation. The increase or decrease of PaCO2 in the blood directly affects the blood carbonic acid content and has an opposite effect on pH. The effect of acute PaCO2 on pH is stronger than that of chronic ones. The reason is that the plasma bicarbonate concentration can not be replenished in time. When the change of PaCO2 lasts for 3 to 5 days, hypercapnia increases the bicarbonate through the renal compensatory mechanism; when hypocapnia is reduced, both can promote The pH returns to normal, so many respiratory failure patients have a mixture of respiratory and non-respiratory acid-base balance disorders. It is difficult to clarify the nature if the disease course and plasma bicarbonate levels are not known.

Elderly respiratory failure prevention

Older respiratory failure is caused by COPD, often repeated episodes continue to increase, seriously affecting the quality of life of patients, should pay attention to the rehabilitation of chronic respiratory failure, such as long-term oxygen therapy, strengthen respiratory function exercise, enhance the body's disease resistance and other measures to reduce recurrence ,improve the quality of life.

Complications of respiratory failure in the elderly Complications, gastrointestinal bleeding, heart failure, respiratory failure, pulmonary edema

Common infections, complicated with gastrointestinal bleeding, shock, electrolyte imbalance, hypovolemia, heart failure or respiratory failure.

Symptoms of respiratory failure in the elderly Common symptoms Dyspnea, respiratory failure, coma, lethargy, sleepiness, wheezing, acute dyspnea, urinary shock, convulsions

1. Clinical features of respiratory failure in elderly patients

(1) easily lead to respiratory failure: a group of 1650 cases of respiratory failure analysis showed that from the beginning of the underlying disease to the development of respiratory failure, in the elderly, 63% in the 5th year, 77% in the 10th year, In the 15th year, it was 88%; among young people, 57%, 68% and 75%, respectively, indicating that older people are more likely to evolve into respiratory failure than younger people.

(2) No special symptoms and clinical manifestations: In the case of respiratory failure in the elderly, only 45.5% of the patients with dyspnea are absent. Although the PaO2 is abnormal, the patient does not necessarily have any discomfort. The respiratory mucosa of the elderly is atrophied and cleared. Decreased function, cough, wheezing and sputum increase is lower than that of young people, and the proportion of conscious disturbances is significantly higher than that of young people.

(3) combined with other organ failure: elderly patients with respiratory failure complicated with multiple organ failure were significantly higher than non-elderly group, especially with heart failure, renal failure is more common; combined with DIC, gastrointestinal bleeding in the second age group is not obvious difference.

2. Common clinical manifestations of respiratory failure

In addition to the symptoms of primary disease that cause respiratory failure, it is mainly caused by hypoxia and CO2 retention, but they are often mixed and difficult to distinguish.

(1) Dyspnea: It is the earliest clinical symptom, and it is aggravated with decreased respiratory function (but not breathing failure). In central respiratory failure, dyspnea is mainly manifested in rhythm and frequency changes. Peripheral respiratory failure caused by respiratory damage, due to the involvement of the respiratory muscles, nodding, shoulder or frown-like breathing, respiratory failure does not necessarily have difficulty breathing, such as central nervous system drug poisoning and respiratory failure CO2 anesthesia stage.

(2) Hairpin: When the absolute value of reduced hemoglobin (Hb) in the blood exceeds 50g/L, the hairpin is generally obvious, but when anemia is observed, the concentration of Hb is significantly decreased, and even if there is obvious hypoxia, there is no cyanosis.

(3) Neuropsychiatric symptoms: The symptoms are mild and hypoxic, the degree of CO2 retention, the body's adaptation and compensation are closely related, acute severe hypoxia can immediately appear mental confusion, arrogance, coma and convulsions, and chronic deficiency Oxygen, with apathy, muscle tremors, lethargy, lethargy, coma and other symptoms.

(4) Circulatory system symptoms: hypoxia and CO2 retention, increased heart rate, increased blood pressure, myocardial ischemia, various arrhythmias; severe hypoxia can cause myocardial contractility, blood pressure, leading to circulatory failure, long-term pulmonary hypertension Will induce right heart failure, symptoms of systemic congestion.

(5) Digestive and urinary system symptoms: there may be anorexia, elevated GPT, gastrointestinal bleeding, elevated urea nitrogen, proteinuria, red blood cells and casts in the urine.

(6) Diffuse intravascular coagulation (DIC): infection, hypoxia, acidosis, shock, etc. can be the predisposing factors of DIC. Improper treatment can lead to DIC.

3. Classification

(1) Classification according to the course of disease:

1 Acute respiratory failure: The patient has no previous respiratory disease, due to sudden factors, inhibition of breathing, or sudden failure of respiratory function, because the body is difficult to compensate well, such as early diagnosis and treatment will endanger the patient's life, such as ARDS.

2 Chronic respiratory failure: more common in chronic respiratory diseases, such as chronic obstructive pulmonary disease, severe tuberculosis, diffuse fibrosis of the lungs, etc., the respiratory function damage is gradually aggravated, although there is hypoxia or carbon dioxide retention, but through the body compensation adaptation, still Being able to engage in personal life activities is called compensatory chronic respiratory failure.

3 acute exacerbation of chronic respiratory failure: patients with chronic respiratory failure, once complicated by respiratory infections, or other reasons to increase the respiratory physiology burden, then decompensation, the occurrence of severe O2, CO2 retention and acidosis clinical manifestations, known as decompensation Chronic respiratory failure.

(2) Classification by blood gas changes:

Type 1I respiratory failure: mainly due to dysfunction of ventilation caused by hypoxia, blood gas analysis showed pure PaO2 <60mmHg.

Type 2 type II respiratory failure: mainly due to insufficient alveolar ventilation, blood gas analysis showed PaO2 <60mmHg, and PaCO2>50mmHg.

(3) According to the classification of lesions: can be divided into peripheral type and central type of respiratory failure.

Elderly respiratory failure check

Arterial blood gas analysis

PaO2<8.0kpa, PaCO2>6.67kPa or low pH can be reduced; chronic respiratory failure, AB compensation increased.

2. Electrolyte determination

There is often high blood K+, HCO3- is increased due to acid recovery, decreased by acid, the result can be high, can be low and normal.

Electrocardiogram: may have sinus arrhythmia, conduction block, atrial and ventricular arrhythmia, non-specific ST segment and T wave changes.

Diagnosis and diagnosis of respiratory failure in the elderly

Early diagnosis of respiratory failure is extremely important. It depends on the clinician's full understanding of its clinical manifestations and causes. Once there are clinical signs, arterial blood gas analysis should be performed early to confirm the diagnosis. It should be distinguished from the tension pneumothorax and persistent state of asthma, and attention should be paid to the identification of acute pulmonary edema, pulmonary infection, pulmonary embolism, acute respiratory distress syndrome and cerebrovascular accident.

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