Stress Testing
A. Indications
- Complaints of dyspnea on exertion (ischemia due to coronary artery disease)
- Determine ventilatory/cardiac limitations to work
- Determine maximum workloads for developing an exercise plan or adjusting daily activities
- For disability purposes
B. Contraindications
- PaO2 less than 45 mmHg on room air
- PaCO2 greater than 70 mmHg
- FEV1 less than 30% predicted
- Recent MI
- Unstable angina
- 2nd or 3rd degree heart block
- Rapid ventricular/atrial arrhythmias
- Congestive heart failure (CHF)
- Uncontrolled hypertension
- Severe pulmonary hypertension
- Severe aortic stenosis
- Orthopedic problems that impair activity
- Neurological disorders that limit ability to perform
- Dissecting aneurysms
C. Protocols
- Bruce
- Naughton
- Uses 10 exercise periods of 3 minutes duration, each separated by rest periods of 3 minutes.
- Grade and speed of each time:
- Period 1: 0%, 1mph
- Period 2: 0%, 1.5 mph
- Period 3: 0%, 2 mph
- Period 4: 3.5%, 2 mph
- Period 5: 7%, 2 mph
- Period 6: 5%, 3 mph
- Period 7: 7.5%, 3 mph
- Period 8: 10%, 3 mph
- Period 9: 12.5%, 3 mph
- Period 10: 15%, 3 mph
- Incremental (sub-maximum) Stress Testing
- Patient is exercised at workloads less than maximum heart rate
- Formula: 220 – age (yrs) = maximum heart rate
- Endpoint of testing is when patient reaches 85% of their maximum heart rate
D. Prep Techniques
- Preparation of the Patient
- Last meal before exercise should be light, 2 hours before test
- Avoid cigarettes, alcohol, coffee, tea, carbonated beverages
- No heavy exercise before test or on same day
- Wear properly fitting clothes
- Room temperature should be 21 degrees – 23 degrees (70-73 F)
- Preliminary Procedures
- Wrapping blood pressure cuff on upper arm (brachial artery)
- Attach 12-lead EKG and 3-lead cardiotachometer
- Secure oximeter to ear
- Show patient how to pedal bicycle or to mount the treadmill
- Establish intravenous (IV) line
- Seated and standing 12-lead ECG
- Have patient hyperventilate prior to testing to document and rule out S-T and T wave abnormalities