Final answer:
Difficulty breathing or increased respiratory distress, a crackling sound in the lungs, and chest pain are adverse signs suggesting pulmonary edema in a postoperative pneumonectomy client.
Step-by-step explanation:
An adverse sign or symptom indicating pulmonary edema in a postoperative pneumonectomy client would be the sudden onset of difficulty breathing or an increase in respiratory distress. Additional signs might include a crackling sound while auscultating the lungs with a stethoscope, which can indicate fluid in the air sacs, or chest pain which is not a usual postoperative symptom. A nurse caring for patients should also keep an eye out for symptoms like an elevated heart rate, hypoxemia (low blood oxygen levels), and the particular presence of a frothy sputum which may be tinged with blood. These signs can help detect pulmonary edema early, which is crucial since this condition can compromise gas exchange in the lungs and can be life-threatening if not addressed promptly.