Direct and indirect evidence of efficacy and safety of rapid exercise tests for exertional desaturation in Covid-19: a rapid systematic review

Abstract

Background Even when resting pulse oximetry is normal in the patient with acute Covid-19, hypoxia can manifest on exertion. We summarise the literature on the performance of different rapid tests for exertional desaturation and draw on this evidence base to provide guidance in the context of acute Covid-19. Main research questions What exercise tests have been used to assess exertional hypoxia at home or in an ambulatory setting in the context of Covid-19 and to what extent have they been validated? What exercise tests have been used to assess exertional hypoxia in other lung conditions, to what extent have they been validated and what is the applicability of these studies to acute Covid-19? Method AMED, CINAHL, EMBASE MEDLINE, Cochrane and PubMed using LitCovid, Scholar and Google databases were searched to September 2020. Studies where participants had Covid-19 or another lung disease and underwent any form of exercise test which was compared to a reference standard were eligible. Risk of bias was assessed using QUADAS 2. A protocol for the review was published on the Medrxiv database. Results Of 47 relevant papers, 15 were empirical studies, of which 11 described an attempt to validate one or more exercise desaturation tests in lung diseases other than Covid-19. In all but one of these, methodological quality was poor or impossible to fully assess. None had been designed as a formal validation study (most used simple tests of correlation). Only one validation study (comparing a 1-min sit-to-stand test [1MSTST] with reference to the 6-min walk test [6MWT] in 107 patients with interstitial lung disease) contained sufficient raw data for us to calculate the sensitivity (88%), specificity (81%) and positive and negative predictive value (79% and 89% respectively) of the 1MSTST. The other 4 empirical studies included two predictive studies on patients with Covid-19, and two on HIV-positive patients with suspected pneumocystis pneumonia. We found no studies on the 40-step walk test (a less demanding test that is widely used in clinical practice to assess Covid-19 patients). Heterogeneity of study design precluded meta-analysis. Discussion Exertional desaturation tests have not yet been validated in patients with (or suspected of having) Covid-19. A stronger evidence base exists for the diagnostic accuracy of the 1MSTST in chronic long-term pulmonary disease; the relative intensity of this test may raise safety concerns in remote consultations or unstable patients. The less strenuous 40-step walk test should be urgently evaluated.

The Neurological Manifestations of Post-Acute Sequelae of SARS-CoV-2 Infection

“…A post-COVID-19 functional status scale has been developed pragmatically but not formally validated [ 124 ]. Pulse oximeters may be extremely useful for assessing and monitoring respiratory symptoms after COVID-19 with no evidence that their home use leads to increased anxiety [ 125 ]. Close to 50% of COVID-19 patients who required hospital admission had hypoxia on exertion without subjective dyspnea at the time of discharge.…”

Exercise-induced hypoxia among emergency department patients admitted for suspected COVID-19

“…As highlighted in a recent systematic review, there remains little published data on EIH and COVID-19, and none of its role within the ED. 7 One recent paper has highlighted a modest association of EIH with critical care needs. 9 Due to public health interventions and falling case numbers at the time of this study, this was not powered to explore concomitant associations.…”

“…[4][5][6] A recent systematic review identified only two studies which have investigated EIH in COVID-19. 7 One study focused on its use at discharge and identification of pulmonary embolism. 8 Another retrospective study of admissions to 70 UK hospitals assessed the association between EIH and subsequent need for mechanical ventilation.…”

“…As highlighted by Kalin et al, such data are important in exploring the role of EIH testing in triaging the need for admission of suspected cases of COVID-19. 7 A 1-minute sit-to-stand exercise test (1MSTST) was incorporated into the ED assessment of COVID-19 at our hospital in March of 2020. We examined the association of EIH and ultimate diagnosis of COVID-19 among patients admitted to hospital for suspected COVID-19.…”

Patterns of oxygen saturation in prolonged recovery from COVID-19 pneumonia

“…the distance that they were able to walk off oxygen, the activities they were able to do, and the length of time that they felt comfortable off oxygen, were slightly more subjective but also useful signs of recovery. The '40 step test' [2,3] was introduced as a means of standardising the level of exertion for the purposes of comparison, even though it has not been validated. • After 2 weeks of static indicators, having excluded other causes, we accepted a new baseline of oxygen saturation, even <90%, and sent the patient home.…”