Respiratory Failure
TERMS
Ventilation-perfusion (V/Q)
QUICK LOOK AT THE CHAPTER AHEAD
Respiratory failure occurs when the system is no longer able to exchange oxygen for carbon dioxide. Either a situation exists where sufficient oxygen is not available for transfer to the blood, resulting in hypoxemia, or carbon dioxide cannot be removed and is allowed to accumulate to dangerous levels, causing hypercapnia. In this chapter we examine hypoxemic and hypercapnic respiratory failure, the clinical manifestations, and treatment and nursing implications.
CAUSESRespiratory failure occurs when the system is no longer able to exchange oxygen for carbon dioxide. Either a situation exists where sufficient oxygen is not available for transfer to the blood, resulting in hypoxemia, or carbon dioxide cannot be removed and is allowed to accumulate to dangerous levels, causing hypercapnia. It is not a disease in itself but the result of a disease, respiratory or otherwise. Two types of respiratory failure exist, hypoxemic failure and hypercapnic failure.
Respiratory failure is not a disease in itself but the result of a disease, respiratory or otherwise.
HYPOXEMIC FAILUREHypoxemia results from three different situations in the lung: alveolar hypoventilation, ventilation-perfusion (V/Q) mismatch, and an intrapulmonary shunt (Figure 44-1). As the term indicates, a lack or insufficient amount of oxygen exists in the blood for proper oxygenation. In hypoxemic failure the PaO2 level falls below 60 mm Hg.
Alveolar Hypoventilation
Hypoventilation may be caused by a variety of conditions and results in decreased pO2 and increased pCO2 levels. Head injury or drug overdose
may cause a decreased respiratory drive, leading to hypoventilation. Neuromuscular conditions exist that affect the respiratory muscles, such as amyotrophic lateral sclerosis or Guillain-Barré. Chest wall dysfunction associated with trauma or lung diseases, such as chronic obstructive pulmonary disease, cystic fibrosis, or acute respiratory distress syndrome, contribute to hypoventilation. Regardless of the cause, all affect the alveoli and gas exchange, causing hypoxemia.
may cause a decreased respiratory drive, leading to hypoventilation. Neuromuscular conditions exist that affect the respiratory muscles, such as amyotrophic lateral sclerosis or Guillain-Barré. Chest wall dysfunction associated with trauma or lung diseases, such as chronic obstructive pulmonary disease, cystic fibrosis, or acute respiratory distress syndrome, contribute to hypoventilation. Regardless of the cause, all affect the alveoli and gas exchange, causing hypoxemia.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
