VALIDITY AND RELIABILITY OF MEASUREMENT OF PERIPHERAL OXYGEN SATURATION DURING THE 6-MINUTE WALK TEST IN PATIENTS WITH SYSTEMIC SCLEROSIS

BackgroundThe 6-Minute Walk Test (6MWT) is a standardised method routinely used to screen for and monitor interstitiel lunge disease and/or pulmonary arterial hypertension in patients with systemic sclerosis (SSc). Studies shows that esaturations during the 6MWT are associated with severity of pulmonary manifestations in patients with SSc [1]. Digital sensors are commonly used to measure peripheral oxygen saturation (SpO2) during the 6MWT. However, digital-based sensors may have important limitations in patients with SSc due to disease-related microangiopathy, Raynaud's phenomenon, sclerodactyly and motion artifacts during the 6MWT [2]. Sensors located at more central body positions may therefore be more accurate as these as less prone to Raynaud attacks.ObjectivesTo determine the validity and re-test reliability of peripheral oxygen saturation measured at the finger, forehead, and ear during the 6MWT in patients with SSc.Methods82 patients with SSc had an arterial line placed while performing the 6MWT. Peripheral oxygen saturation was simultaneously measured by finger, forehead, and earlobe sensors and compared to the arterial oxygen saturation (SaO2) measured before and after the 6MWT. 40 patients repeated the 6MWT one week later. We used Bland-Altman plots to display the agreement between SpO2 and SaO2, and between the minimal SpO2 (minSpO2) one week apart. The intraclass correlation coefficient (ICC, 95% confidence interval 95% CI]) for repeated measurement of minSpO2 was calculated.ResultsThe mean difference (SpO2 - SaO2, ± standard deviation [SD]) after the 6MWT was –3.3% (±4.82), 0.15% (±1.55), and 1.36% (±1.93) for the finger, forehead, and earlobe, respectively (Table 1).The finger minSpO2 also demonstrated the poorest re-test reliability: The mean difference in minSpO2 (visit2-visit1, ±SD) was 1.28% (±5.3), 0.74% (±4.36) and –1.10% (±2.87),). The ICC (95% CI) showed good agreement using the ear and forehead probe (ICCear = 0.89 [0.80;0.94];ICCforehead = 0.88 [0.60;0.87]), while a modest reliability was found using the finger probe (ICCfinger = 0.65 [0.43;0.80]).ConclusionPeripheral oxygen saturation should be measured using either the earlobe or forehead during the 6MWT in patients with SSc.References[1]Villalba, W. O. et al. Six-minute walk test for the evaluation of pulmonary disease severity in scleroderma patients. Chest 131, 217–222 (2007).[2]Pathania, Y. S. Alternatives for erroneous finger probe pulse oximetry in systemic sclerosis patients during COVID-19 pandemic. Rheumatol. Int. 41, 2243–2244 (2021).Table 1.Validity and re-test reliability of peripheral oxygen during the 6MWT (n= 82)Finger probeForehead probeEar probeMean difference SpO2 - SaO2  Mean difference pre-test (+/-SD)–0.68% (±1.88)0.13% (±1.26)1.54% (±0.69)  Mean difference post--test (+/-SD)–3.30% (±4.82)0.15% (±1.55)1.36% (±1.93)Mean difference of the minSpO2 (visit2-visit1)  Mean difference (±SD)1.28% (±5.3)0.74% (±4.36)1.10% (±2.87)Abbreviations: SpO2, Peripheral oxygen saturation;SaO2, Arterial oxygen saturation;SD, Standard deviation.Acknowledgements:NIL.Disclosure of InterestsAmanda Lynggaard Riis: None declared, Esben Naeser Paid instructor for: Boehringer Ingelheim Denmark, Katja Thorup Aaen: None declared, Henrik Hovgaard: None declared, Peter Juhl-Olsen: None declared, Elisabeth Bendstrup Speakers bureau: Hoffman-la-Roche.Boehringer Ingelheim.Glaxo Smith Kleine.Daichii Sankyo, Klaus Soendergaard Speakers bureau: Boehringer Ingelheim, Consultant of: Boehringer Ingelheim, Grant/research support from: Boehringer Ingelheim.

COVID-19 in patients with Pulmonary Alveolar Proteinosis A European multicenter study

Background: Interruption of GM-CSF signaling leads to Pulmonary Alveolar Proteinosis (PAP), occasionally to lung infections and relates to the impaired ability of lung macrophages to catabolize phagocytized surfactant and handle microbes. COVID-19 is associated with worse prognosis in lung disorders. We hypothesized that PAP patients would be at increased risk for COVID-19 and poor outcome. Aim and objectives: This multi-center, retrospective, European study aimed to investigate prevalence and clinical consequences of COVID-19 in PAP and the impact of iGM-CSF treatment on hospitalization or death. Method(s): All patients with PAP and COVID-19 diagnosed and followed-up in 11 referral European centers from January 24th 2020 to August 31st 2021 were included. Prevalence, clinical course and outcome were investigated. Result(s): COVID-19 developed in 34/255 (13.3%) of patients, mostly adults (91.2%), all with autoimmune (a)PAP;all patients were infected before the preventive option of vaccination was available;11 (35.5%) were hospitalized, of whom almost half were in the ICU;3 (27%) of hospitalized patients either died or underwent lung-transplant;these three patients had worse DLCO% predicted (p=0.019) and had more often arterial hypertension (AH) (p=0.012), and a smoking history (p=0.002). All patients with mild disease treated at home survived. Among children, 3 developed COVID-19 with good outcome. Conclusion(s): PAP patients experienced similar rates of COVID-19 with the general population but increased rates of hospitalizations and deaths, underscoring the vulnerability of this population and the necessity of preventive measures to avoid infection. If infected, secondary prophylaxis with monoclonal antibodies and the impact of iGM-CSF must be considered.

Fatigue in Long Covid-19 is associated to short hospitalization time and normal lung function

Background: Reports of long-lasting symptoms after covid-19 have raised serious concerns. Specifically, fatigue seems to be a predominant symptom after hospitalization with Covid-19. Aims and objectives: To investigate the burden of fatigue after hospitalization with Covid-19. Method(s): Patients hospitalized with PCR-proven Covid-19 in Central Denmark Region were invited for follow-up 3-6 months after discharge. Assessment included self-reported symptoms, Fatigue Assessment Score (FAS), and pulmonary function test (PFT) with registration of percent predicted forced expiratory volume in one second (FEV1%) and diffusion capacity (DLCO%). Basic characteristics from hospitalization were registered. Result(s): Among 218 patients (median age 59.9, 59% males) median FAS score was 24.0 (IQR 18.0-32.0). Patients were subdivided into three categories based on disease severity;Group A: Patients without oxygen (n=57), Group B: Patients requiring oxygen therapy at the ward (n=120) and Group C: patients admitted at ICU (n=41). Group A had a median length of hospital stay of 1.0 day (IQR 0.0-2.0), which was significantly shorter than Group B (5 days, p<0.05) and Group C (23 days, p<0.05). Fatigue was most common in group A: 52% reported mild-to-moderate fatigue and 25% reported severe fatigue. In contrast, severe fatigue was reported by 16% in Group B and 14% in Group C. Median FEV1% was 106.0% (94.0-112.0), DLCO% 89.5% (IQR 77.5-98.0) in Group A. Median DLCO% was significantly lower in Group B (83.0%, p<0.05) and in Group C (70.0%, p<0.05). Conclusion(s): Significant fatigue is frequent after hospitalization with Covid-19 and associated to short length of hospital stay and normal lung function tests.

Characterization of patients with severe fatigue after hospitalization with Covid-19

Background: SARS-CoV-2 virus, causing Covid-19, continues to be a public health concern. Long-term sequela after infection with Covid-19 has been reported worldwide and holds the risk of becoming a major health concern. Ongoing symptoms more than 3 months after infection is now defined as long Covid. Fatigue and psychological distress are among the most common symptoms in long Covid. Aim: To investigate severe fatigue and psychological distress after hospitalization in patients with Covid-19. Methods: Patients hospitalized with Covid-19 in the Central Denmark Region were invited for follow-up 3- 6 months after discharge. Psychological distress was measured by Hospital Anxiety and Depression Scale (HADS) with a HADS score ≥8 identifying cases of anxiety and depression in the two subdomains. Fatigue was assessed using Fatigue Assessment Scale (FAS) with a FAS ≥35 indicating severe fatigue. Basic characteristics from the hospitalization were registered. Results: A total of 218 patients (mean age 59.9 (95% CI 58.2, 61.7), 59% men) reported a mean HADS of 7.9 (95% CI 6.95, 8.93). Cases of anxiety and depression were found in 23 and 16% of all patients, respectively. Overall, a mean FAS of 25.6 (95% CI 24.3, 26.9) was found with 34 patients (18%) reporting severe fatigue. Patients with severe fatigue (mean age of 54.2 (95% CI 50.3, 58.1), 47% males), cases of anxiety and depression was reported by 59 and 62%, respectively. Analyses of FAS in subdomains on mental and physical fatigue showed mean scores of 19.3 (95% CI 18.5, 20.2) and 20.6 (95% CI 19.8, 21.5), respectively. Conclusion: Severe fatigue is common after hospitalization in patients with Covid-19 and includes both mental and physical fatigue. In addition, cases of anxiety and depression are common in patients with severe fatigue.