Final answer:
Option D. The first nursing action after a segmental lung resection would be to monitor oxygen saturation, as it provides crucial immediate information regarding the patient's respiratory function and oxygenation post-surgery.
Step-by-step explanation:
The first nursing action after assessing a client who has returned to the medical-surgical unit following a segmental lung resection would be to monitor oxygen saturation. This is crucial because the patient has just had surgery that affects the respiratory system, and ensuring adequate oxygenation is a priority. Post-operative patients are at risk for complications such as airway obstruction or reduced lung function due to general anesthesia, which can impact the muscles necessary for breathing.
Once the patient’s oxygenation status is ensured, additional nursing actions like administering pain medication, suctioning excessive tracheobronchial secretions, or assisting the client to turn, deep breathe, and cough can be carried out as needed. These actions are critical for the patient's recovery, but they follow the assessment of vital signs and oxygen saturation for immediate life-sustaining requirements.