AARC GUIDELINE: EXERCISE TESTING FOR EVALUATION OF HYPOXEMIA AND/OR DESATURATION: 2001 REVISION & UPDATE AARC Clinical Practice Guideline Exercise Testing for Evaluation of Hypoxemia and/or Desaturation: 2001 Revision & Update ETD 1.0 PROCEDURE: cation skills of the patient being served, Exercise testing for evaluation of hypoxemia should be taken into consideration when and/or desaturation. performing these tests. 2.5.2 The neonatal population is not ETD 2.0 DESCRIPTION/DEFINITION: served by this guideline. Exercise testing may be performed to determine the degree of oxygen desaturation and/or hypoxemia ETD 3.0 SETTINGS: that occurs on exertion. Desaturation is defined as a Exercise testing may be performed by trained valid decrease in arterial oxygenation as measured personnel in a variety of settings including by CO-oximetry saturation, (SaO2) of 2% (based on 3.1 pulmonary function laboratories the reproducibility of HbO measurement at ±1%),1 2 3.2 cardiopulmonary exercise laboratories an S 2 < 88%,2,3 and/or a blood gas P 2 ≤ 55 torr.4 aO aO 3.3 clinics 2.1 Exercise testing may also be performed to 3.4 pulmonary rehabilitation facilities optimize titration of supplemental oxygen for 3.5 physicians’ offices the correction of hypoxemia. An SpO2 of 93% should be used as a target.3 ETD 4.0 INDICATIONS: 2.2 It is preferable that this procedure be per- Indications for exercise testing include formed using a method that allows quantitation 4.1 the need to assess and quantify the adequa- of workload and heart rate achieved (as % pre- cy of arterial oxyhemoglobin saturation during dicted). exercise in patients who are clinically suspect- 2.2.1 This evaluation can be incorporated ed of desaturation (eg, those who manifest dys- into other more complex test protocols pnea on exertion, decreased DLCO, decreased (eg, cardiac stress testing). PaO2 at rest, or documented pulmonary dis- 2.2.2 Continuous noninvasive measure- ease);2,7,15-18 ment of arterial oxyhemoglobin saturation 4.2 the need to quantitate the response to thera- by pulse oximetry can provide qualitative peutic intervention (eg, oxygen prescription, information and an approximation of oxy- medications, smoking cessation, or to reassess hemoglobin saturation,RETIRED with a 4% de- the need for continued supplemental oxy- 4 2,7,15,19-21 crease in SpO2 considered significant, but gen); evaluation of desaturation on exertion re- 4.3 the need to titrate the optimal amount of quires analysis of arterial blood samples supplemental oxygen to treat hypoxemia or de- drawn with the subject at rest and at peak saturation during activity;2,7,21,22 exercise.3,5-12 4.4 the need for preoperative assessment for 2.3 Arterial blood specimens may be obtained lung resection or transplant;23 by single puncture or by arterial cannulation.13,14 4.5 the need to assess the degree of impairment 2.4 Exercise testing performed with exhaled gas for disability evaluation (eg, pneumoconiosis, analysis is addressed in a separate guideline. asbestosis).24 2.5 This guideline is appropriate for pediatric, adult, and geriatric patients who are capable of ETD 5.0 CONTRAINDICATIONS: following test instructions and techniques. 5.1 Absolute contraindications include 2.5.1 The learning ability and communi- 5.1.1 acute electrocardiographic changes 514 RESPIRATORY CARE • MAY 2001 VOL 46 NO 5 AARC GUIDELINE: EXERCISE TESTING FOR EVALUATION OF HYPOXEMIA AND/OR DESATURATION: 2001 REVISION & UPDATE suggesting myocardial ischemia or seri- by exercise;25,26 ous cardiac dysrhythmias including 5.2.8 uncontrolled metabolic disease (eg, bradydysrhythmias, tachydysrhythmias, diabetes, thyrotoxicosis, or myxede- sick sinus syndrome, and multifocal pre- ma;25,26 26 mature ventricular contractions (PVCs), 5.2.9 SaO2 or SpO2 < 85% on room air; causing symptoms or hemodynamic com- 5.2.10 complicated or advanced pregnan- promise (occasional PVCs are not a con- cy;25 traindication);25-29 5.2.11 hypertrophic cardiomyopathy or 5.1.2 unstable angina;24,25,27 other forms of outflow tract obstruction;26 5.1.3 recent myocardial infarction (within 5.2.12 patient’s inability to cooperate or the previous 4 weeks) or myocarditis;25,26 follow directions for testing. 5.1.4 aneurysm of the heart or aorta;25,26 5.1.5 uncontrolled systemic hyperten- ETD 6.0 PRECAUTIONS AND/OR POSSIBLE sion;25,26 COMPLICATIONS: 5.1.6 acute thrombophlebitis or deep ve- 6.1 Indications for immediate termination of nous thrombosis;25,26 testing include 5.1.7 second- or third-degree heart 6.1.1 electrocardiographic abnormalities block;25,26 (eg, dangerous dysrhythmias, ventricular 5.1.8 recent systemic or pulmonary embo- tachycardia, ST-T wave changes);25,26 lus;25,26 6.1.2 severe desaturation as indicated by 25,26 5.1.9 acute pericarditis; an SaO2 ≤80% or SpO2 ≤83% (A number of 5.1.10 symptomatic severe aortic steno- pulse oximeters have been found to over- 3,12,33-36 sis; estimate SpO2 ) and/or a 10% fall 5.1.11 uncontrolled heart failure;25 from baseline values; (Underestimation of 5.1.12 uncontrolled or untreated asthma; saturation has been noted to occur with 5.1.13 pulmonary edema;25 certain pulse oximeter models.33,34) 5.1.14 respiratory failure;25 6.1.3 angina;25,26 5.1.15 acute non-cardiopulmonary disor- 6.1.4 hypotensive responses; ders affected by exercise. 6.1.4.1 a fall of > 20 torr in systolic 5.2 Relative contraindications include pressure, occurring after the normal ex- 5.2.1 situations in which pulse oximetry ercise rise;37 may provide invalid data (eg, elevated 6.1.4.2 a fall in systolic blood pressure HbCO, HbMet, or decreased perfusion). below the pre-exercise level;36 (See AARC Pulse Oximetry Guidelines.30) 6.1.5 lightheadedness;25,26 5.2.2 situations in which arterial puncture 6.1.6 request from patient to terminate and/or arterial cannulation may be con- test. traindicated;31,32 RETIRED6.2 Abnormal responses that may require dis- 5.2.3 a non-compliant patient or one who continuation of exercise include is not capable of performing the test be- 6.2.1 a rise in systolic blood pressure to > cause of weakness, pain, fever, dyspnea, 250 torr or of diastolic pressure to > 120 incoordination, or psychosis;25,26 torr,25,26 or a rise in systolic pressure of < 5.2.4 severe pulmonary hypertension (cor 20 torr from resting level; pulmonale);25,26 6.2.2 mental confusion or headache;25,26 5.2.5 known electrolyte disturbances (hy- 6.2.3 cyanosis;25,26 pokalemia, hypomagnesemia);25,26 6.2.4 nausea or vomiting; 5.2.6 resting diastolic blood pressure > 6.2.5 muscle cramping.25,26 110 torr or resting systolic blood pressure 6.3 Hazards associated with arterial puncture, > 200 torr;25,26 arterial cannulation, and pulse oximetry:30-32 5.2.7 neuromuscular, musculoskeletal, or Pulse oximetry is a noninvasive safe procedure, rheumatoid disorders that are exacerbated but because of device limitations, false-nega- RESPIRATORY CARE • MAY 2001 VOL 46 NO 5 515 AARC GUIDELINE: EXERCISE TESTING FOR EVALUATION OF HYPOXEMIA AND/OR DESATURATION: 2001 REVISION & UPDATE tive results for hypoxemia11 and/or false-posi- 7.1.1.7 Pulse oximeter response time tive results for normoxemia or hyperoxemia may be inadequate to describe rapid may lead to inappropriate treatment of the pa- changes in saturation.7,16,45 tient. Although it is rare, tissue injury may 7.1.1.8 Skin pigmentation should, in occur at the measuring site as a result of probe theory, not affect pulse oximeter read- misuse, such as pressure sores from prolonged ings, but various studies report con- application or electrical shock and burns from flicting data depending on the manu- the substitution of incompatible probes be- facturer and model.3,45 tween instruments.30,38-42 7.1.1.9 Hemoglobin disorders may af- fect the accuracy of the pulse oximeter ETD 7.0 LIMITATIONS OF PROCEDURE/ reading.16,33,45 Important underestima- VALIDATION OF RESULTS: tion of arterial saturation may result 7.1 Limitations of equipment: from pulse oximetry in subjects with 7.1.1 Because of possible limitations of total hemoglobin levels of ≤8 g/dL.53 pulse oximetry with exercise and at rest, 7.1.1.10 Pulse oximetry is less useful measurements may read falsely low or over the range in which large changes falsely high and should be validated by in PaO2 are associated with small 16 comparison with baseline arterial samples changes in SaO2 (ie, PaO2 ≥60 torr). analyzed by CO-oximetry.30,33,43 7.1.1.11 Ambient light during testing 7.1.1.1 Only a limited number of pulse may interfere with measurements of oximeters have been validated with re- pulse oximetry.45 sults of concurrent arterial blood gas 7.1.1.12 Exercise testing in which oxy- analysis in diseased subjects under ex- hemoglobin saturation by pulse oxime- ercise conditions.16 try is the only variable measured pro- 7.1.1.2 Overestimation of oxygen satu- vides limited information. ration may occur with carboxyhe- 7.1.2 Limitations related to the patient: moglobin saturations (> 4 %).2,44,45 7.1.2.1 Additional limitations common 7.1.1.3 Decreasing accuracy in SpO2 to arterial sampling and analysis under has been reported with desaturations to resting conditions should be consid- < 83%. This is assumed to be the result ered.31,32 of limitations of in vivo calibration to 7.1.2.2 Patient cooperation level or 85% with extrapolation of the calibra- physical condition may limit the sub- tion curve below that value.13,45 ject’s ability to exercise at a workload 7.1.1.4 Decreased perfusion with car- sufficient to evoke a response.25,26 Vari- diovascular disease, vasoconstriction, ables that are not adequately monitored or hypothermia may result in false- (eg, free walking) have limited applica- positive results or noRETIRED valid data in tion.