A patient who has a right-sided chest tube following a thoracotomy has continuous bubbling in the suction-control chamber of the collection device. The most appropriate action by the nurse is to

Rationale:

A. Prepare to administer a sedative is incorrect because the client is already experiencing respiratory alkalosis (pH 7.50, PaCO₂ 29 mm Hg) due to hyperventilation. Although she is tachypneic, sedation could suppress respiratory drive and worsen hypoxemia (PaO₂ 60 mm Hg, SaO₂ 86%). Suppressing respirations in a hypoxic patient can lead to respiratory failure. Sedation does not address the underlying oxygenation problem and could be dangerous at this stage.

B. Administer oxygen via face mask is correct. This client is hypoxemic, as evidenced by a PaO₂ of 60 mm Hg and SaO₂ of 86% (normal PaO₂ is 80–100 mm Hg; normal SaO₂ ≥95%). According to the ABC priority framework (Airway, Breathing, Circulation), oxygenation is the immediate priority. Supplemental oxygen will increase the fraction of inspired oxygen (FiO₂), improve arterial oxygen levels, and reduce tissue hypoxia. The ABG values show respiratory alkalosis caused by hyperventilation, commonly seen in suspected pulmonary embolism. Immediate oxygen therapy is critical before further diagnostic procedures.

C. Prepare for mechanical ventilation is incorrect because although the client is tachypneic, she is still breathing spontaneously and does not show signs of respiratory failure such as rising PaCO₂, severe fatigue, altered level of consciousness, or inability to maintain airway. Mechanical ventilation is indicated when respiratory effort fails or oxygenation cannot be maintained despite supplemental oxygen. At this stage, less invasive oxygen delivery is the priority.

D. Assess for indications of pulmonary embolism is incorrect as the priority intervention, although it is clinically very relevant. This client has significant risk factors for pulmonary embolism, including oral contraceptive use and smoking, along with symptoms of sudden dyspnea, pleuritic chest pain, tachycardia, hypoxemia, and respiratory alkalosis — classic findings associated with conditions such as pulmonary embolism described in resources like Pulmonary embolism. However, while further assessment and rapid provider notification are essential, the immediate priority is correcting hypoxemia by administering oxygen. Assessment follows stabilization.

Rationale:

A. Prednisone is a corticosteroid used to suppress inflammation and immune responses in conditions such as asthma, autoimmune diseases, and allergic reactions. Prednisone does not have vasodilatory effects and does not interact with sildenafil in a way that could cause life-threatening complications. Therefore, taking sildenafil while on prednisone is not contraindicated.

B. Nitroglycerine is a nitrate commonly prescribed for angina or ischemic heart disease. Nitrates work by releasing nitric oxide, which causes vasodilation and decreased blood pressure. Sildenafil, a phosphodiesterase-5 (PDE5) inhibitor, also enhances nitric oxide-mediated vasodilation, particularly in the systemic and pulmonary circulation. When these two drugs are taken together, the effects add synergistically, which can lead to severe, life-threatening hypotension, syncope, myocardial ischemia, or even cardiac arrest. Because of this risk, the combination of sildenafil and nitrates is considered an absolute contraindication. Patients must be screened carefully for any nitrate use, including short-acting nitroglycerin for chest pain, before starting sildenafil.

C. Phenytoin is an anticonvulsant used to control seizures. It is metabolized by the liver’s cytochrome P450 system and can increase the metabolism of sildenafil, reducing its effectiveness. While this may require dose adjustment or timing considerations, it does not pose a life-threatening risk and is therefore not an absolute contraindication.

D. Metronidazole is an antibiotic used to treat anaerobic bacterial infections. It has no direct cardiovascular interactions with sildenafil and does not cause dangerous hypotension. There may be minor pharmacokinetic interactions in some cases, but these are not contraindications.