National Registry of Certified Medical Examiners (NRCME) DOT Practice Exam

A driver who exhibits difficulty breathing and has a history of COPD should undergo additional pulmonary testing. A forced expiratory volume in the first second of expiration (FEV1) less than what level of predicted should prompt arterial blood gas measurements?

1. 50%

2. 55%

3. 65%

4. 70%

The correct answer is: 65%

The correct action in this scenario is to have an arterial blood gas measurement prompted by a forced expiratory volume in the first second of expiration (FEV1) that falls below a certain predictive threshold. The FEV1 is a critical measurement in assessing lung function and can indicate the severity of airflow obstruction, especially in conditions like Chronic Obstructive Pulmonary Disease (COPD). A threshold of less than 65% of the predicted FEV1 value is significant because it correlates with a greater likelihood of respiratory failure and the need for closer examination of the patient's oxygen and carbon dioxide levels in the bloodstream. This level indicates a more severe impairment in lung function that can lead to hypoxemia (insufficient oxygen in the blood) or hypercapnia (excess carbon dioxide). At this stage, the patient may also be at increased risk for complications, requiring further evaluation through arterial blood gas measurements. The other percentage thresholds are not as critical for prompting arterial blood gas measurements, as values above 65% generally suggest a lower level of respiratory distress. Thus, the 65% threshold is a clinically relevant point where further intervention and monitoring are warranted to ensure patient safety and effective management of their condition.