![Room9er ["Room Niner"]:](https://room9er.com/wp-content/uploads/2020/03/cropped-Screen-Shot-2020-03-08-at-3.16.16-PM.png)
In patients with some suspicion for PE, even with a negative d dimer, I have often ordered a walking O2 sat and HR. This was not really evidence based, but maybe now could be. Below is the abstract for a prospective cohort study of patients known to be with and without PE. Interesting data even if only 114 patients. Cannot get full text yet.
Take home point. Combined sensitivity of HR increase of 10 BPM AND Sat decreased of >/= 2% was 100%.
ie if HR does not go up by 10 or more AND sat does not drop by 2 or more they are very unlikely, based on this small study, to have a PE.
Ambulatory vital signs in the workup of pulmonary embolism using a standardized 3-minute walk test.
Abstract
OBJECTIVE:
Diagnosing pulmonary embolism can be difficult given its highly variable clinical presentation. Our objective was to determine whether a decrease in oxygen saturation or an increase in heart rate while ambulating could be used as an objective tool in the diagnosis of pulmonaryembolism.
METHODS:
This was a two-site tertiary-care-centre prospective cohort study that enrolled adult emergency department or thrombosis clinic patients with suspected or newly confirmed pulmonary embolism. Patients were asked to participate in a standardized 3-minute walk test, which assessedambulatory heart rate and ambulatory oxygen saturation. The primary outcome was pulmonary embolism.
RESULTS:
We enrolled 114 patients, including 30 with pulmonary embolism (26.3%). A ≥2% absolute decrease in ambulatory oxygen saturation and an ambulatory change in heart rate >10 beats per minute (BPM) were significantly associated with pulmonary embolism. An ambulatory heart rate change of >10 BPM had a sensitivity of 96.6% (95% confidence interval [CI] 83.3 to 99.4) and a specificity of 31.0% (95% CI 22.1 to 45.0) forpulmonary embolism. A ≥2% absolute decrease ambulatory oxygen saturation had a sensitivity of 80.2% (95% CI 62.7 to 90.5) and a specificity of 39.3% (95% CI 29.5 to 50.0) for pulmonary embolism. The combination of both variables yielded a sensitivity of 100.0% (95% CI 87.0 to 100.0) and a specificity of 11.0% (95% CI 6.6 to 21.0).
CONCLUSION:
In summary, our study found that an ambulatory heart rate change of >10 BPM or a ≥2% absolute decrease in ambulatory oxygen saturation from baseline during a standardized 3-minute walk test are highly correlated with pulmonary embolism. Although the findings appear promising, neither of these variables can currently be recommended as a screening tool for pulmonary embolism until larger prospective studies examine their performance either alone or with pre-existing rules.