Maximal voluntary ventilation (MVV), also known as maximal breathing capacity, is the maximum amount of air that the patient can breathe per minute with maximal voluntary effort. This test measures several physiologic phenomena occurring at the same time, including thoracic cage compliance, lung compliance, R_aw, and available muscle force.

1. Have the patient either sit or stand. Place nose clips on the nose and instruct the patient to breathe normally through a mouthpiece/filter (bacterial/viral) combination into the spirometer.

2. Instruct the patient to breathe into the spirometer as deeply and rapidly as possible for 10–15 seconds. Usually, the frequency reaches 40–70 breaths per minute, and the tidal volumes are about 50% of the VC.

3. The actual values are extrapolated from the 10- to 15-second time interval to a 1-minute time period.

4. Typically, the maneuver is performed twice, and the largest value is reported.

1. Obstructive ventilatory impairments of moderate to severe degree, abnormal neuromuscular control, and poor patient effort are causes of low values.

2. In restrictive disease, the value is usually normal; however, in more severe forms, MVV may be decreased.

Pretest Patient Care

1. Explain the purpose and procedure of the test. Explain that it is a noninvasive test that requires patient cooperation. Assess the patient’s ability to follow verbal instructions.

2. Record the patient’s age, height, and gender.

3. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Poor patient effort can be ruled out by using the following formula to predict the MVV of the patient:

This is a useful check to determine whether the recorded MVV is indicative of adequate patient effort. Low values can be related to patient effort and not to pathophysiology.

Normal

• Approximately 80–120 L/min in women and 140–180 L/min in men

• Predicted values are based on the patient’s age, height, and gender. A healthy person may vary by as much as 25%–35% from mean group values.