September 2002 / Volume 47 / Number 9 / Page 986
Clinical Utility of Measures of Breathlessness
Respiratory therapists provide many treatments to relieve shortness of breath, including oxygen therapy and ventilator care. Yet current clinical practice guidelines rarely recommend dyspnea measurement instruments as a means of patient evaluation. The reason for that omission is uncertain. Perhaps dyspnea evaluation has not been demonstrated to be beneficial in today's fast-paced health care environment? Given the emphasis on patient outcomes in health care, the clinical utility of dyspnea measures should be explored and a paradigm for their administration developed.
During the infancy of inhalation therapy, respiratory treatments consisted of high volumes of aerosol and medication therapy to soothe mucosa and provide bronchodilation. There was limited interest in quantifying breathlessness, and more consideration was given to treatment of breathing difficulties. That emphasis on treatment continues today. Without emphasis on assessing the patient's improvement in pulmonary function and oxygenation, little documentation of treatment outcomes is available to clinicians.
Dyspnea measures have been used to assess patient response to exercise, activities of daily living (ADL), and rehabilitation, and have been included in assessment of health-related quality of life. For example, recent attention has been given to dyspnea treatment and assessment during mechanical ventilation in the context of patient-centered care.
Although many methods are available to evaluate breathlessness, the most effective measure for a specific patient condition or treatment remains largely unexplored in the respiratory care literature. The American Thoracic Society Consensus Guideline on Dyspnea states that dyspnea instruments should be applied as related to the purpose for which they were intended. That consensus statement presents valuable scientific evidence on the mechanisms, assessment, and management of dyspnea. Additionally the statement noted, "Inventories that embrace aspects of dyspnea related to quality of life are not yet a routine part of the history and physical examination, but have demonstrated a useful role in the clinic and in pulmonary rehabilitation." Although no specific recommendations were forthcoming, the consensus statement does describe dyspnea inventories used for exercise as well as the broader context of instruments for dyspnea in regards to quality of life. It is necessary to differentiate between a breathing function and breathing as it affects ADL. One can have the ability to breathe and yet not have adequate oxygenation to perform ADL such as dressing and climbing stairs. It is also possible for a patient to show no change in limited objective measures of breathing function and yet to show increased ability to cope with ADL.
Mishoe and MacLean recommend that only those tools that have documented sound psychometric properties be applied to clinical practice and research. Psychometric properties include validity, reliability, and responsiveness, among others. Tables 1 and 2 provide definitions of some commonly used psychometric terms.
Important questions include:
- How should dyspnea be evaluated?
- When should evaluation occur?
- Which instrument is most appropriate in a specific patient situation?
- Do different patient conditions require different instruments?
- How do psychometric properties affect the use of these instruments?
The purpose of this study is to evaluate and then to classify the clinical utility of measures of breathlessness, either as single-symptom or multidimensional instruments, based on psychometric foundations such as validity and reliability, as well as discriminative or evaluative properties. We make recommendations for clinical application of each dyspnea measure, in terms of exercise, benchmarking patients, ADL, patient outcomes, clinical trials, and response to treatment. Evaluation of each dyspnea measure analyzed can guide assessment of patient progress, treatment effectiveness, and short-term or long-term therapy goals. This template will assist respiratory clinicians to identify the best measures for clinical practice guideline inclusion or clinical application.