Acute Respiratory Failure Overview

Study Notes

Defined as a drop in arterial oxygen tension (PaO2) to less than 50 mm Hg and a rise in arterial carbon dioxide tension (PaCO2) to greater than 50 mm Hg, with an arterial pH of less than 7.35.
A major cause of morbidity and mortality in intensive care units (ICUs).
Clinical manifestations of type I and II respiratory failure differ.
Type I failure is a direct defect in oxygenation.
Type II failure is a direct defect in ventilation.

Type I (hypoxemic): Result of abnormal oxygen transport secondary to pulmonary parenchymal disease, with increased alveolar ventilation resulting in a low PaCO2.
Type II (hypercapnic): Result of inadequate alveolar ventilation, with marked carbon dioxide elevation, and relative oxygenation preservation.
Combined (types I & II): A combination of inadequate alveolar ventilation and abnormal gas transport.

Type I: Hypoxemia is the hallmark, primarily due to V/Q mismatch or intrapulmonary shunting.
Type II: Hypercapnia is the hallmark, resulting from alveolar hypoventilation, which may be caused by decreased respiratory drive, neuromuscular disorders, or chest wall pathology.
Diffusion impairment: A rare cause of impaired oxygenation, involving thickening or destruction of the alveolar-capillary membrane.

Intrinsic lung/airway diseases: Chronic bronchitis, acute bronchiolitis, asthma, parenchymal diseases (pneumonia, pulmonary embolism), and chest wall abnormalities (pneumothorax, obesity).
Extra-pulmonary disorders: Neuromuscular junction disorders (muscular dystrophies, botulism), peripheral nerve problems (Guillain-Barré syndrome), spinal cord trauma, and central nervous system conditions (drug overdose, cerebral hypoxia, cerebrovascular accident, or sleep apnea).

Pulmonary symptoms: Dyspnea, cough, hemoptysis, wheezing, chest pain, orthopnea, paroxysmal nocturnal dyspnea, and sinus problems.
Extrapulmonary symptoms: Night sweats, headaches, weight changes, fluid retention, nasal stuffiness, discharge, and history of smoking, childhood respiratory illnesses, family respiratory history, environmental exposures, previous respiratory problems.

Treat underlying cause: Address the root cause of the failure, such as infection, respiratory muscle weakness, or lung disease.
Improve oxygenation and ventilation: Administer supplemental oxygen (high flow oxygen), and mechanical ventilation, possibly with assistance of pressure support.
Weaning from ventilation: Gradually reducing or discontinuing mechanical support as the patient's condition improves.

Purpose: To maintain adequate tissue oxygenation and reduce the work of breathing.
Types of ventilation: Positive pressure ventilation (e.g., volume-cycled, pressure-cycled, time-cycled) and negative-pressure ventilation (e.g., iron lung). Continuous Mandatory Ventilation, Assist Controlled Mode, and Synchronized Intermittent Mandatory Ventilation.
Indications: Conditions where spontaneous breathing is inadequate or ineffective to support adequate gas exchange.

Focus on improving oxygenation and ventilation; monitoring and managing complications (e.g., infection, barotrauma, and hypoxemia).
Close monitoring of vital signs, arterial blood gases (ABGs), respiratory status, and fluid balance.
Implementing appropriate nursing interventions based on the patient's specific needs and condition.