A nurse is preparing to administer diphenhydramine 25 mg IM stat to a client who is having an allergic reaction.

Available is diphenhydramine 50 mg/mL. How many milliliters should the nurse administer per dose?

Choice A rationale

A flow rate of 5 liters per minute is generally too high for a patient with chronic obstructive pulmonary disease. High concentrations of oxygen can abolish the hypoxic drive in these patients. In chronic CO2 retainers, the central chemoreceptors become desensitized to high carbon dioxide levels, leaving low oxygen levels as the primary stimulus for breathing. Providing 5 liters could lead to hypoventilation, carbon dioxide narcosis, and potentially lethal respiratory arrest in susceptible individuals.

Choice B rationale

Delivering 8 liters per minute of oxygen is contraindicated for most individuals with chronic obstructive pulmonary disease unless they are in acute respiratory failure and being closely monitored with mechanical ventilation. This high flow rate significantly increases the partial pressure of arterial oxygen, which suppresses the peripheral chemoreceptors in the carotid and aortic bodies. The result is a dangerous decrease in minute ventilation and an exacerbation of hypercapnia and respiratory acidosis.

Choice C rationale

A flow rate of 2 liters per minute is the standard starting point for patients with chronic obstructive pulmonary disease to maintain an oxygen saturation between 88 percent and 92 percent. This level provides sufficient oxygenation to prevent tissue hypoxia while ensuring the arterial oxygen level does not rise high enough to suppress the patient's natural respiratory drive. Normal arterial oxygen (PaO2) for healthy adults is 80 to 100 mmHg, but COPD patients often compensate at lower levels.

Choice D rationale

A flow rate of 10 liters per minute is an excessive amount of supplemental oxygen for a stable COPD patient. Such high flows are typically reserved for emergency situations using non-rebreather masks. In the context of chronic management, this flow rate would almost certainly lead to a significant rise in PaCO2. Clinical guidelines emphasize using the lowest possible dose of oxygen to achieve adequate saturation to avoid the complications associated with oxygen-induced hypercapnia and loss of drive.

Choice A rationale

Ambulation is a critical intervention for preventing atelectasis because physical movement encourages deeper breathing and the expansion of the lungs. Walking increases the tidal volume and helps mobilize secretions that might otherwise collect in the lower lobes and cause alveolar collapse. By shifting the patient’s position and increasing metabolic demand slightly, ambulation promotes better ventilation-perfusion matching throughout the pulmonary system. It is one of the most effective non-invasive ways to maintain lung health postoperatively.

Choice B rationale

Encouraging coughing and deep breathing is a standard nursing intervention to prevent the collapse of small airways and alveoli. Deep breathing exercises increase the pressure within the lungs, helping to pop open collapsed alveoli through collateral ventilation. Coughing provides the necessary force to move mucus from the smaller airways into the larger ones where it can be expectorated. This reduces the risk of mucus plugging, which is a primary cause of obstructive atelectasis in surgical patients.

Choice C rationale

Maintaining a client in a supine position at all times is actually a risk factor for atelectasis rather than a prevention strategy. When a patient lies flat, the abdominal contents push upward against the diaphragm, and gravity causes the posterior lung fields to be compressed. This restricts full lung expansion and leads to the collapse of the dependent alveoli. Frequent repositioning and elevating the head of the bed are preferred to ensure maximal lung expansion and better gas exchange.

Choice D rationale

This choice is incorrect because the incentive spirometer is designed for inhalation, not exhalation. Educating a patient to blow into the device would not achieve the goal of alveolar expansion. The purpose of the incentive spirometer is to provide visual feedback as the patient takes a slow, deep breath in, which creates sustained maximal inspiration. This process increases transpulmonary pressure and helps re-expand collapsed lung tissue. Blowing into the device would be ineffective for treating atelectasis.

Choice E rationale

While promoting self-care is important for stroke rehabilitation, allowing a patient with a recent stroke to feed themselves without supervision is a safety risk regarding aspiration. Aspiration can lead to pneumonia or focal atelectasis if foreign material enters the bronchial tree. This intervention does not directly target the mechanical expansion of the alveoli or the prevention of lung collapse. Furthermore, stroke patients often have dysphagia, making unmonitored feeding a dangerous practice rather than a preventive lung intervention.

Choice F rationale

Proper technique for using an incentive spirometer involves creating a tight seal around the mouthpiece and inhaling slowly and deeply. A slow, sustained inhalation is necessary to ensure that the air reaches the most distal parts of the lungs, including the alveoli that are at risk of collapsing. The goal is to reach a target volume and hold the breath for several seconds to maximize the recruitment of lung tissue. This specific educational point is essential for effective treatment.