Inverse association between blood pressure and pulse oximetry accuracy: an observational study in patients with suspected or confirmed COVID-19 infection.

BACKGROUND: Pulse oximeters are a standard non-invasive tool to measure blood oxygen levels, and are used in multiple healthcare settings. It is important to understand the factors affecting their accuracy to be able to use them optimally and safely. This analysis aimed to explore the association of the measurement error of pulse oximeters with systolic BP, diastolic BP and heart rate (HR) within ranges of values commonly observed in clinical practice. METHODS: The study design was a retrospective observational study of all patients admitted to a large teaching hospital with suspected or confirmed COVID-19 infection from February 2020 to December 2021. Data on systolic and diastolic BPs and HR levels were available from the same time period as the pulse oximetry measurements. RESULTS: Data were available for 3420 patients with 5927 observations of blood oxygen saturations as measured by pulse oximetry and ABG sampling within 30 min. The difference in oxygen saturation using the paired pulse oximetry and arterial oxygen saturation difference measurements was inversely associated with systolic BP, increasing by 0.02% with each mm Hg decrease in systolic BP (95% CI 0.00% to 0.03%) over a range of 80-180 mm Hg. Inverse associations were also observed between the error for oxygen saturation as measured by pulse oximetry and with both diastolic BP (+0.03%; 95% CI 0.00% to 0.05%) and HR (+0.04%; 95% CI 0.02% to 0.06% for each unit decrease in the HR). CONCLUSIONS: Care needs to be taken in interpreting pulse oximetry measurements in patients with lower systolic and diastolic BPs, and HRs, as oxygen saturation is overestimated as BP and HR decrease. Confirmation of the oxygen saturation with an ABG may be appropriate in some clinical scenarios.

Is vaccination against Covid-19 associated with autoimmune rheumatic disease flare? A self-controlled case series analysis.

OBJECTIVES: To investigate the association between vaccination against Covid-19 and autoimmune rheumatic disease (AIRD) flare. METHODS: Patients with AIRDs vaccinated against Covid-19 who consulted for disease flare between 01/12/2020 and 31/12/2021 were ascertained in Clinical Practice Research Datalink (Aurum). AIRD flare was defined as consultation for AIRD with corticosteroid prescription on the same day or the next day. Vaccination was defined using date of vaccination and product code. The observation period was partitioned into vaccine-exposed (21-days after vaccination), pre-vaccination (7-days before vaccination), and remaining vaccine-unexposed periods. Participants contributed data with multiple vaccinations and outcomes. Season adjusted incidence rate ratios (aIRR) and 95% confidence intervals (CI) were calculated using self-controlled case-series analysis. RESULTS: Data for 3554 AIRD cases, 72% female, mean age 65 years, and 68.3% with rheumatoid arthritis were included. Covid-19 vaccination was associated with significantly fewer AIRD flares in the 21-day vaccine-exposed period when all vaccinations were considered (aIRR(95%CI) 0.89(0.80-0.98)). Using dose-stratified analyses there was a statistically significant negative association in 21-days after first Covid-19 vaccination but no association after the second or third Covid-19 vaccinations (aIRR(95%CI) 0.76(0.66-0.89), 0.94(0.79-1.11) and 1.01(0.85-1.20) respectively). On AIRD type stratified analyses, vaccination was not associated with disease flares. Vaccination without or after SARS-CoV-2 infection, and with vectored DNA or mRNA vaccines associated with comparable reduced risk of AIRD flares in the vaccine-exposed period after first Covid-19 vaccination. CONCLUSION: Vaccination against Covid-19 was not associated with increased AIRD flares regardless of prior Covid-19, AIRD type, and whether mRNA or DNA vaccination technology were used.

Barriers and facilitators to vaccination uptake against COVID-19, influenza, and pneumococcal pneumonia in immunosuppressed adults with immune-mediated inflammatory diseases: A qualitative interview study during the COVID-19 pandemic.

OBJECTIVES: To explore barriers and facilitators to COVID-19, influenza, and pneumococcal vaccine uptake in immunosuppressed adults with immune-mediated inflammatory diseases (IMIDs). METHODS: Recruiting through national patient charities and a local hospital, participants were invited to take part in an in-depth, one-to-one, semi-structured interview with a trained qualitative researcher between November 2021 and January 2022. Data were analysed thematically in NVivo, cross-validated by a second coder and mapped to the SAGE vaccine hesitancy matrix. RESULTS: Twenty participants (75% female, 20% non-white) were recruited. Barriers and facilitators spanned contextual, individual/group and vaccine/vaccination-specific factors. Key facilitators to all vaccines were higher perceived infection risk and belief that vaccination is beneficial. Key barriers to all vaccines were belief that vaccination could trigger IMID flare, and active IMID. Key facilitators specific to COVID-19 vaccines included media focus, high incidence, mass-vaccination programme with visible impact, social responsibility, and healthcare professionals' (HCP) confirmation of the new vaccines' suitability for their IMID. Novel vaccine technology was a concern, not a barrier. Key facilitators of influenza/pneumococcal vaccines were awareness of eligibility, direct invitation, and, clear recommendation from trusted HCP. Key barriers of influenza/pneumococcal vaccines were unaware of eligibility, no direct invitation or recommendation from HCP, low perceived infection risk, and no perceived benefit from vaccination. CONCLUSIONS: Numerous barriers and facilitators to vaccination, varying by vaccine-type, exist for immunosuppressed-IMID patients. Addressing vaccine benefits and safety for IMID-patients in clinical practice, direct invitation, and public-health messaging highlighting immunosuppression as key vaccination-eligibility criteria may optimise uptake, although further research should assess this.