Final answer:
Successful intervention for ineffective airway clearance is indicated by clear breath sounds upon auscultation. Spirometry and stethoscope use are tools to evaluate and monitor patient lung function and airway clearance.
Step-by-step explanation:
A postoperative patient with a nursing diagnosis of ineffective airway clearance would be determined to have successful intervention if 'c. Patient's breath sounds are clear to auscultation.' This outcome indicates that the patient's airways are free from blockages or secretions that can hinder breathing, hence effective airway clearance. Other options, such as fluid intake and spirometer use, are supportive actions but do not directly measure the clearance of the airway. A normal temperature is also important but again does not directly indicate effective airway clearance.
Spirometry can be a tool in evaluating airway clearance by measuring the rate at which air can be expelled from the lungs, thus helping in the diagnosis of restrictive diseases. It serves as part of the care plan for patients to monitor their lung function. Auscultation, through the use of a stethoscope, allows healthcare providers to listen for clear breath sounds, which would be an immediate indication of effective airway clearance.