Exercise Tolerance: Evaluating Organ Function Without Lab Values

Have you ever had a patient who simply didn’t get better? Their test results matched the clinical practice guideline so closely you were confident they should be responding to your interventions. You believed the patient was diligently doing their home exercises, yet they didn’t progress. So, what else could have kept them from getting better?

Did their referring provider indicate they had other medical diagnoses that were under control? Understandably, you may not think that a previous diagnosis would impact their exercise tolerance, but it could.

Factors Impacting Exercise Tolerance

In these cases, there are many factors that could be impacting the patient’s exercise tolerance. Changes to diets or medications can significantly affect the activity tolerance for people with limited cardiac or renal function. Even minor adjustments can cause change in organ function, which may already be compromised by their comorbidities. This impaired organ function can impact the ion concentration in their blood and body fluids, and subsequently affect their overall exercise tolerance.

How will you determine if their impaired response is due to their comorbidities? Since you are not in an acute care setting, you don’t have lab values to help guide your assessment. Although ongoing lab testing can be helpful, the result is just a number that does not serve as a stand-alone decision-making tool in any setting.

Identifying Health Problems Based on Patient History

Regardless of setting, the gestalt of symptoms and pertinent patient-reported history can tell you a lot about their health. Consider asking yourself the following questions:

• Did the patient present with a higher or irregular resting heart rate compared to usual?
• Did exercise elevate the patient’s blood pressure like in previous sessions?
• Did the patient mention changes in diet, bowel, or bladder habits since the last exam?

Some of these changes can impact both exercise response and resting signs and symptoms. This is the result of impaired renal or cardiac function, which doesn’t allow the patient to adapt to even small shifts in diet or fluid loss. Sometimes the changes are dramatic enough that you may choose to refer them back to their primary care provider.

Other Ways to Identify Health Problems Without Lab Values

Even when you don’t have access to a recent lab analysis, it can be postulated that a patient may have values outside of the reference range if they demonstrate symptoms consistent with specific ion deficiencies and are predisposed by their recent or past medical history. A patient’s recent history may include changes in symptoms, bowel and bladder habits, or behavior. Their past medical history could be renal failure that is no longer under control.

Addressing the many aspects of a patient’s presentation at rest and with activity can help you determine if you should refer a patient back to their primary care provider or if they can safely progress with discrete monitoring.