Hope Hospital, Salford, UK
Correspondence to: Ronan O’Driscoll, MD, Consultant Chest Physician, Department of Cardio-Respiratory Medicine, H3 Teaching Block, Hope Hospital, Stott Lane, Salford, M6 8HD United Kingdom; e-mail: Ronan.O’Driscoll@SRHT.NHS.UK
We read with interest the article by Hadeli et al (July 2001)1 concerning oxygen desaturation during submaximal exercise testing in a pulmonary function laboratory. We use a slightly different exercise protocol during medical consultations with patients who attend our chest clinic because of breathlessness. Patients climb on and off a 18-cm high exercise step in the consulting room while being monitored by pulse oximetry. Patients are instructed to climb the steps as quickly as they find comfortable and to stop if they are breathless, fatigued, or distressed in any other way. We reviewed the records of 119 patients with mixed lung disorders (mostly asthma, COPD, or pulmonary fibrosis) who had undergone laboratory lung function tests (Jaeger; Wurzburg, Germany) in addition to a clinical exercise test. There was a strong relationship between the transfer coefficient (KCO) and the patient’s oxygen saturation level (Table 1
These data support the finding of Hadeli et al that reduced gas transfer is predictive of oxygen desaturation during exercise (and vice versa), whether the diffusing capacity of the lung for carbon monoxide or KCO is used to assess gas transfer. Our data also support their suggestion that a gas transfer below a threshold of about 60% is strongly predictive of oxygen desaturation during everyday tasks such as stair climbing. Our findings also support the use of a threshold of > 3% oxygen desaturation as a clinically meaningful change from baseline oxygen saturation during exercise. Minor oxygen desaturation (or fluctuation in the oximeter reading) was common in subjects with normal gas transfer values, but a fall of > 3% was uncommon in the absence of significant lung disease. However, care must be taken to avoid motion or pressure artifacts. Excessive motion of the patient’s hand or pressure on the fingertip can cause significant artifacts in the oximeter reading.
Our results indicate that this simple test can be extended from the pulmonary function laboratory to the clinical consulting room where the clinician can gain useful information about the patient’s cardiopulmonary function. The test also allows the physician to assess the patient’s motivation and noncardiopulmonary limiting factors such as arthritis or physical deconditioning. This assessment takes only 2 or 3 min to perform, and it is much more convenient in routine clinical practice than a 6-min walking test or shuttle walking test. We recommend the use of exercise oximetry in the consulting room as a routine component of consultations for breathless patients.
Spo2 = pulse oximetric saturation; CI = confidence interval.
Become a CHEST member and receive a FREE subscription as a benefit of membership.
Individuals can purchase this article on ScienceDirect.
Individuals can purchase a subscription to the journal.
Individuals can purchase a subscription to the journal or buy individual articles.
Learn more about membership or Purchase a Full Subscription.
Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.
Some tools below are only available to our subscribers or users with an online account.
Download citation file:
Web of Science® Times Cited: 3
Customize your page view by dragging & repositioning the boxes below.
Enter your username and email address. We'll send you a reminder to the email address on record.
Athens and Shibboleth are access management services that provide single sign-on to protected resources. They replace the multiple user names and passwords necessary to access subscription-based content with a single user name and password that can be entered once per session. It operates independently of a user's location or IP address. If your institution uses Athens or Shibboleth authentication, please contact your site administrator to receive your user name and password.