Chronic Obstructive Airways Pulmonary Disease(COPD) | What Is It ? | Disease Respiratory
- Respiratory failure
Respiratory Failure of Chronic Obstructive Airways Diseases (COPD)
Respiratory failure is inadequate gas exchange by the respiratory system, with the result that levels of arterial oxygen, carbon dioxide or both cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial carbon dioxide levels is called hypercapnia. The normal reference values are: oxygen PaO2 more than 80 mmHg (11 kPa), and carbon dioxide PaCO2 lesser than 45 mmHg (6.0 kPa). It is classified into type I or type II which relates to the absence or presence of hypercapnia respectively. Hypoxemic respiratory failure (type I): It is characterized by an arterial oxygen tension (Pa O2) lower than 60 mm Hg with a normal or low arterial carbon dioxide tension (Pa CO2). This is the most common form of respiratory failure, and it can be associated with virtually all acute diseases of the lung, which generally involve fluid filling or collapse of alveolar units. Some examples of type I respiratory failure is cardiogenic or non-cardiogenic pulmonary edema, pneumonia and pulmonary hemorrhage.
Hypercapnic respiratory failure (type II): It is characterized by a PaCO2 higher than 50 mm Hg. Hypoxemia is common in patients with hypercapnic respiratory failure who are breathing room air. The pH depends on the level of bicarbonate, which, in turn, is dependent on the duration of hypercapnia. Common etiologies include drug overdose, neuromuscular disease, chest wall abnormalities, and severe airway disorders (e.g, asthma and chronic obstructive pulmonary disease).Respiratory failure may be further classified as either acute or chronic.
Acute respiratory failure is characterized by life threatening derangements in arterial blood gases and acid-base status. The manifestations of chronic respiratory failure are less dramatic and may not be as readily
Acute hypercapnic respiratory failure develops over minutes to hours; therefore, pH is less than 7.3 (blood). Chronic respiratory failure develops over several days or longer, allowing time for renal compensation and an increase in bicarbonate concentration. Therefore, the pH usually is only slightly decreased.
Causes Of Chronic Obstructive Airways Diseases
Common causes of type I (hypoxemic) respiratory failure include the following:
- Pulmonary edema
- Pulmonary fibrosis
- Pulmonary embolism
- Pulmonary arterial hypertension
- Granulomatous lung diseases
- Cyanotic congenital heart disease
- Acute respiratory distress syndrome (ARDS)
- Fat embolism syndrome
Common causes of type II (hypercapnic) respiratory failure include the following:
- Severe asthma
- Drug overdose, poisonings
- Myasthenia gravis
- Primary muscle disorders
- Cervical cordotomy
- Head and cervical cord injury
- Primary alveolar hypoventilation
- Obesity-hypoventilation syndrome
- Pulmonary edema
- ARDS (adult respiratory distress syndrome)
Symptoms Of Chronic Obstructive Pulmonary Disease(COPD)
A majority of patients with respiratory failure are short of breath. Both low oxygen
and high carbon dioxide can impair mental functions. Patient may become confused and disoriented and find it impossible to carry out their normal activities and work.
- Marked CO2 excess can cause headaches and, in time, a semiconscious state, restlessness, anxiety, confusion, seizures, or even coma.
- Low blood oxygen causes bluish coloration in skin, fingertips and lips.
- Tachycardia and cardiac arrhythmias may result from hypoxaemia and acidosis.
- Polycythaemia is a complication of long standing hypoxaemia.
- Corpulmonale (failure of the right side of the heart): Pulmonary hypertension is frequently present and may induce right ventricular failure, leading to hepatomegaly and peripheral oedema.
- Physical examination may show a patient who is breathing rapidly, is restless and has a rapid pulse.
- Lung disease may cause abnormal sounds; wheezing in asthma, “crackles” in obstructive lung disease. A patient with ventilatory failure is prone to gasp (catch one’s breathe with an open mouth, owing to pain or astonishment) for breath, and may use the neck muscles to help expand the chest.
Complications In Chronic Obstructive Pulmonary Disease(COPD)
- Pulmonary fibrosis.
- Collapsed lung (pneumothorax).
- Blood clots.
- Abnormal lung function.
- Memory, cognitive and emotional problems.