Other Respiratory Disorders

Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Diffuse alveolar damage involves damage to the endothelial and alveolar epithelial cells and is associated with inflammation and the development of hyaline membranes lining the inner alveolar walls. The reparative stage follows after weeks, with fibrosis possibly occurring later. Clinically, the following triad of findings favors a diagnosis of ARDS: acute or rapidly progressive dyspnea, hypoxic respiratory failure (partial pressure of O2/fraction of inspired O2 ratio < 300 mm Hg), and bilateral alveolar opacities on chest imaging. Management involves the determination and treatment of the cause while providing adequate oxygen, reducing further lung damage, and avoiding fluid overload. Most patients require mechanical ventilation. Acute respiratory distress syndrome is associated with high mortality or long-term complications potentially developing even after treatment.

Obstructive sleep apnea (OSA) is a common disorder in adults, characterized by recurrent obstruction of the upper airway during sleep, causing hypoxia and fragmented sleep.  OSA is due to a partial or complete collapse of the upper airway and is associated with snoring, restlessness, sleep interruption, fatigue, and daytime somnolence. Untreated OSA is associated with an increased risk of cardiovascular disease, hypertension, pulmonary arterial hypertension, and accidents related to hypersomnolence. The diagnosis relies on medical history, and polysomnography can confirm the diagnosis. Most cases remain undiagnosed. Management includes lifestyle changes, methods of positive airway pressure, and surgical intervention.

The respiratory system is responsible for eliminating the volatile acid carbon dioxide (CO2), which is produced via aerobic metabolism. The body produces approximately 15,000 mmol of CO2 daily, which is the majority of daily acid production; the remainder of the daily acid load (only about 70 mmol of nonvolatile acids) is excreted through the kidneys. In the setting of hypoventilation, this acid load is not adequately blown off, and respiratory acidosis occurs. Renal compensation occurs after 3–5 days, as the kidneys attempt to increase the serum bicarbonate levels. Patients are often asymptomatic, or they may present with neuropsychiatric manifestations or mild dyspnea. Diagnosis is made with arterial blood gas measurement. Management involves treating the underlying etiology, stabilizing the patient, and avoiding respiratory sedatives.

"The respiratory system is responsible for eliminating the volatile acid carbon dioxide (CO2), which is produced via aerobic metabolism. The body produces approximately 15,000 mmol of CO2 daily, which is the majority of daily acid production; the remainder of the daily acid load (only about 70 mmol of nonvolatile acids) is excreted through the kidneys. When hypoventilation occurs, excess carbon dioxide is blown off and respiratory alkalosis develops. The kidneys respond by decreasing serum bicarbonate (HCO3–) through increased HCO3– excretion or decreased excretion of H+. Patients present with an increased respiratory rate, dyspnea, light-headedness and potentially psychologic symptoms. Diagnosis involves a thorough history, an exam, and an arterial blood gas measurement. Management focuses on addressing the underlying abnormalities, stabilizing patients in acute distress, and potentially a small dose of short-acting benzodiazepines.  "

Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Diffuse alveolar damage involves damage to the endothelial and alveolar epithelial cells and is associated with inflammation and the development of hyaline membranes lining the inner alveolar walls. The reparative stage follows after weeks, with fibrosis possibly occurring later. Clinically, the following triad of findings favors a diagnosis of ARDS: acute or rapidly progressive dyspnea, hypoxic respiratory failure (partial pressure of O2/fraction of inspired O2 ratio < 300 mm Hg), and bilateral alveolar opacities on chest imaging. Management involves determination and treatment of the cause while providing adequate oxygen, reducing further lung damage, and avoiding fluid overload. Most patients require mechanical ventilation. Acute respiratory distress syndrome is associated with high mortality or long-term complications potentially developing even after treatment.

Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. A number of etiologies exist, including diseases of the lungs, cardiovascular, and nervous system. Patients with respiratory failure may present with dyspnea, tachypnea, and altered mentation. The diagnosis is made with arterial blood gas and supplemented with laboratory and imaging studies to elicit an etiology. Management involves treating the underlying cause, supplemental oxygen administration, and mechanical ventilation for severe cases.

Obstructive sleep apnea (OSA) is a disorder characterized by recurrent obstruction of the upper airway during sleep, causing hypoxia and fragmented sleep. Obstructive sleep apnea is due to a partial or complete collapse of the upper airway and is associated with snoring, restlessness, sleep interruption, and daytime somnolence. The diagnosis relies on medical history, and polysomnography can confirm the diagnosis. Management includes lifestyle changes, methods of positive airway pressure, and surgical intervention.

The pH of the blood is tightly regulated within the range 7.35–7.45 to ensure proper physiologic functions. Large amounts of acid are generated each day through normal processes (aerobic/anaerobic respiration and dietary intake), and these are efficiently managed and eliminated by buffers in the blood, the respiratory system, and the renal system. When these regulatory systems are disturbed, acid–base balance disorders occur, including respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis.