This article is to discuss Respiratory failure regarding its Definition,Types , causes, clinical picture and methods of treatment.
Provided with normal atmospheric O2 tension and absence of A- V shunts.
So respiratory failure is mainly a laboratory diagnosis.
Causes
Acute
- Acute pulmonary edema - ARDS
- Pneumonia
- Pulmonary embolism.
Chronic
- Pure emphysema
- Interstitial Pulmonary fibrosis-Lymphangitis carcinomatosa.
Type II: Hypoxic hypercapnic
It is mainly due to ventilation defect so : Low O2 and High CO2
Causes:
Acute
• Respiratory muscle paralysis (see neurological causes of hypoventilation)
• Acute severe asthma.
Chronic
• Obstructive hypoventilation. e.g. COPO
• Restrictive hypoventilation e.g. pulmonary fibrosis and kyphoscoliosis.
Patient with chronic bronchitis + emphysema will suffer from ventilation +diffusion defect + perfusion defect --> Hypoxia and Hypercapnia (type II respiratory failure).
• Acute : Central cyanosis, tachypnea, tachycardia, convulsions and impaired consciousness.
• Chronic : Central cyanosis, clubbing, P++, cor pulmonale, polycythaemia,fatigue and drowziness.
(2) Features of hypercapnea.
Acute : Confusion then coma,
Chronic : Headache, drowsiness, hypersomnia (C02 narcosis), flabbing tremors, +++ ICT with papilloedema.
(3) Features of the cause.
2- O2 therapy according to the type :
Type I
There is Hypoxia with No Hypercapnia i.e CO2 retention is not a risk.
• So we can give O2 with high concentration
• Treatment of the cause
• Mechanical ventilation If necessary in acute cases and controlled long term O2 therapy in chronic cases.
Type II
There is Hypoxia + Hypercapnia , So ++ C02 --> decreases sensitivity of respiratory center to Co2, So
hypoxia --> stimulate peripheral chemoreceptors --> stimulation of breathing (Hypoxic drive) so correction of hypoxia
leads to depression of respiratory center .
• So in ttt of type II give low flow O2 to preserve the hypoxic drive.
• Mechanical ventilation if necessary in acute or chronic cases.
• Also we can use doxapram as a respiratory stimulant.
• Controlled long term O2 therapy in chronic cases.
Definition of Respiratory failure
It is a decline in the respiratory performance leading to hypoxia ± hypercapnea with the following arterial blood gases :
Provided with normal atmospheric O2 tension and absence of A- V shunts.
So respiratory failure is mainly a laboratory diagnosis.
Types of respiratory failure
Type I : Hypoxic normocapnic or hypocapnic as CO2 may be washed due to hyperventilation, it is mainly diffusion defect.Causes
Acute- Acute pulmonary edema - ARDS
- Pneumonia
- Pulmonary embolism.
Chronic
- Pure emphysema
- Interstitial Pulmonary fibrosis-Lymphangitis carcinomatosa.
Type II: Hypoxic hypercapnic
It is mainly due to ventilation defect so : Low O2 and High CO2
Causes:
Acute
• Respiratory muscle paralysis (see neurological causes of hypoventilation)
• Acute severe asthma.
Chronic
• Obstructive hypoventilation. e.g. COPO
• Restrictive hypoventilation e.g. pulmonary fibrosis and kyphoscoliosis.
Patient with chronic bronchitis + emphysema will suffer from ventilation +diffusion defect + perfusion defect --> Hypoxia and Hypercapnia (type II respiratory failure).
Clinical Picture
(1) Features of hypoxia.• Acute : Central cyanosis, tachypnea, tachycardia, convulsions and impaired consciousness.
• Chronic : Central cyanosis, clubbing, P++, cor pulmonale, polycythaemia,fatigue and drowziness.
(2) Features of hypercapnea.
Acute : Confusion then coma,
Chronic : Headache, drowsiness, hypersomnia (C02 narcosis), flabbing tremors, +++ ICT with papilloedema.
(3) Features of the cause.
Treatment of respiratory failure:
1- Treatment of the cause and precipitating factor e.g antibiotics, bronchodilators, steroids.2- O2 therapy according to the type :
Type I
There is Hypoxia with No Hypercapnia i.e CO2 retention is not a risk.
• So we can give O2 with high concentration
• Treatment of the cause
• Mechanical ventilation If necessary in acute cases and controlled long term O2 therapy in chronic cases.
Type II
There is Hypoxia + Hypercapnia , So ++ C02 --> decreases sensitivity of respiratory center to Co2, So
hypoxia --> stimulate peripheral chemoreceptors --> stimulation of breathing (Hypoxic drive) so correction of hypoxia
leads to depression of respiratory center .
• So in ttt of type II give low flow O2 to preserve the hypoxic drive.
• Mechanical ventilation if necessary in acute or chronic cases.
• Also we can use doxapram as a respiratory stimulant.
• Controlled long term O2 therapy in chronic cases.