When caring for a client with chronic obstructive pulmonary disease who is ordered continuous oxygen, which oxygen flow rate is MOST appropriate?

Choice A rationale

Metabolic acidosis is characterized by a primary decrease in bicarbonate or an accumulation of nonvolatile acids in the blood. While patients with severe illness can develop multiple imbalances, the primary issue in COPD is not metabolic in origin. In metabolic acidosis, the lungs typically respond by hyperventilating to blow off carbon dioxide to raise the pH. This is the opposite of the hypoventilation and carbon dioxide retention typically seen in patients with chronic obstructive pulmonary disease.

Choice B rationale

Respiratory alkalosis occurs when there is excessive elimination of carbon dioxide from the lungs, usually due to hyperventilation. This leads to an increase in blood pH levels above 7.45. In a client with severe COPD, the primary physiological challenge is the inability to exhale carbon dioxide effectively due to air trapping and alveolar destruction. Therefore, these patients are much more likely to retain carbon dioxide rather than eliminate too much of it through the respiratory system.

Choice C rationale

Metabolic alkalosis involves a primary increase in bicarbonate levels or a loss of metabolic acids, leading to a blood pH greater than 7.45. This condition can be caused by factors like prolonged vomiting or excessive diuretic use. While some COPD patients on certain medications might experience metabolic shifts, it is not the classic acid-base imbalance associated with the underlying pathophysiology of obstructive lung disease and the resulting chronic failure of the respiratory pump to clear gas.

Choice D rationale

Respiratory acidosis is the hallmark of severe COPD due to chronic airflow obstruction and impaired gas exchange. The damaged alveoli and narrowed airways lead to the retention of carbon dioxide, which is a physiological acid. As carbon dioxide levels rise above the normal range of 35 to 45 mmHg, the blood pH drops below 7.35. This client’s report of dyspnea with minimal exertion suggests a high level of CO2 retention and a state of chronic respiratory acidosis.

Choice A rationale

While a cough is a common symptom of pulmonary tuberculosis, it is typically productive rather than non-productive as the disease progresses. The inflammatory response to the Mycobacterium tuberculosis bacteria in the lung tissue leads to the production of purulent sputum, which may also contain blood, a condition known as hemoptysis. A completely dry, non-productive cough is less characteristic of the cavitary lesions and tissue necrosis that usually occur in active pulmonary tuberculosis cases.

Choice B rationale

Skin discoloration is not a classic or primary diagnostic finding associated with the initial evaluation of pulmonary tuberculosis. While chronic illness can eventually lead to pallor due to anemia or cyanosis if oxygenation is severely impaired, these are non-specific signs. Tuberculosis primarily affects the respiratory system and causes systemic constitutional symptoms rather than specific dermatological changes. Diagnostic focus remains on respiratory secretions, chest imaging, and systemic inflammatory responses like fevers and weight loss.

Choice C rationale

Leg cramps are generally unrelated to the pathophysiology of Mycobacterium tuberculosis infection. Cramping is more commonly associated with electrolyte imbalances, such as low potassium or magnesium, or peripheral vascular issues. While a patient with advanced tuberculosis may experience generalized muscle wasting or weakness due to cachexia, localized leg cramps do not help rule in or rule out a diagnosis of tuberculosis during a clinical evaluation of a suspected respiratory infection.

Choice D rationale

Night sweats are one of the hallmark constitutional symptoms of active pulmonary tuberculosis. This occurs due to the body's cytokine response to the chronic infection, which alters the hypothalamic thermoregulatory set point. These sweats are often profuse and occur specifically during the night, frequently soaking the patient's clothes or bed linens. Along with a low-grade afternoon fever, weight loss, and a persistent cough, night sweats strongly suggest the presence of a chronic mycobacterial infection.