What test most reliably indicates if a pulmonary rehab patient has quit smoking?

• A. Methemoglobin level
• B. Treadmill trial
• C. Complete PFT
• D. Carboxyhemoglobin level

Answer: (D)

The carboxyhemoglobin level is the most reliable test for indicating whether a pulmonary rehab patient has quit smoking. This is because carboxyhemoglobin is formed when carbon monoxide binds to hemoglobin in the blood, primarily from smoking tobacco. Smoking increases the levels of carboxyhemoglobin, and measuring this level can provide a direct indication of recent exposure to carbon monoxide.

When a patient quits smoking, the levels of carboxyhemoglobin in the blood will decrease, reflecting the absence of ongoing exposure to cigarette smoke. Monitoring this level can help healthcare providers assess the effectiveness of smoking cessation efforts and the patient's commitment to quitting.

While other choices such as methemoglobin level, treadmill trials, or complete pulmonary function tests (PFTs) provide valuable health information, they do not specifically and reliably indicate smoking cessation. Methemoglobin levels are often related to different types of exposure or conditions, treadmill tests focus on exercise capacity rather than smoking status, and complete PFTs evaluate lung function but do not directly measure smoking habits. Therefore, carboxyhemoglobin level is a targeted and effective measure for assessing a patient's smoking status.