Types Of Respiratory Failure

There are  four types: Determined by a particular pathophysiology and etiology.

Type 1: Failure due to hypoxia
Type 2 Hypercapnic failure
Type 3: Similarities Type 1: Owing to pulmonary atelectasis during the perioperative or postoperative phases.
Type 4: Similar to Type 2, this condition is brought on by shock-induced reduction in respiratory muscle perfusion.

Type 1 Respiratory Failure

There are two possible scenarios for this oxygenation deficiency, which is caused by  ↓ FiO2: normal or ↑ PaO2.
• High altitude (poor ambient oxygen environment)
• Pathogenic
 A few patients are on ventilators, under general anesthesia, or experiencing equipment malfunction.  ↓ Minute ventilation (amount of total air entering the alveoli), which can eventually cause hypoventilation and make it harder for the patient to expel carbon dioxide,

Eventually, patients with ↓ minute ventilation transition from Type 1 to Type 2 respiratory failure. Individuals with minute ventilation or ↓ FiO2 can have a normal A-a gradient. Mismatch between V and Q.
The gradient of A-a is ↑.  Lung atelectasis brought on by consolidation or collapse: an A-a gradient is typical.  Defects in diffusion: The gradient A-a is ↑.

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Type 2 Respiratory Failure

 Lower PaO2;  PaCO2 >50 mm Hg.  The A-a gradient is normal because the drop in blood oxygenation is directly correlated with the drop in alveolar oxygenation.
Factors

• Respiratory generator flaws;
• CNS lesions mostly impact the brain stem.
• Metabolic conditions such as myxoedema and hypothyroidism.
• CNS suppressants, such as anesthetics and morphine.
• Dysfunction of the chest wall that is either genuinely muscular or neuromuscular.
• GBS;  Poliomyelitis;  Myopathies
• Cervical level spinal cord lesions—Hypokalaemia, Hypermagnesemia, Scoliosis.

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Dysfunction Of The Effector Organ

• Patients with chronic bronchitis in the majority.
• Patients with emphysema typically experience type 1 RF.
• Severe asthma, which can result in tiredness, reduced muscle oxygenation, and shock in the patient. All of these problems can be taken into consideration.
• From Type 1, ARDS can develop into Type 2 RF. Resulting from:  Severe impact on lung parenchyma
• Severe hypoxia
• Extended breathing exercises.

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Type 3 Respiratory Failure

Normal or ↓ PaCO2 as a result of greater wash out.  Type 1 subset.
Owing to pulmonary atelectasis during the perioperative or postoperative phases.  When the patient is in a supine position for an extended period of time both before and after surgery; When the patient is under general anesthesia.

Contributory causal factors, also known as risk factors.
Ascites; Insufficient analgesia;  Pain perception restricts breathing efforts.

 Lung atelectasis is caused by ↓ FRC. A patient's diaphragm may be forced upward if they are obese or experiencing ascites, which might reduce their capacity for diaphragmatic descent, particularly while they are supine. These conditions are partly caused by anesthesia.

Following the absorption of air in the dependent lung portion, atelectasis and collapse result.

Treatment  

Most of it is avoidable. Chest physical therapy, incentive spirometry, and oxygen supplementation.

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Type 4 Respiratory Failure

Similar to Type 2, this condition is brought on by shock-induced perfusion of the respiratory muscles, such as cardiogenic shock.Left heart failure is usually present in patients with oncogenic failure. Since the patient already has hypoxia, the respiratory system, including accessory muscles, is exhibiting increased effort (hyperventilation). As a result, the respiratory muscles may absorb up to 10 times the oxygen flow or 40% of the cardiac output, which could be harmful to other important organs.

Treatment

 Mechanical Ventilation: the patient is sedated and intubated.  Supplementing with oxygen alone may be harmful.

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Hope you found this blog helpful for your NEET SS Pulmonology Preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.