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OBJECTIVES: Consensus guidelines for perioperative anesthesia management during the COVID-19 pandemic recommend that patients wear a facemask in addition to their oxygen mask or nasal cannulae following tracheal extubation, where this is practical. The effects on effective oxygen delivery and ventilation of a surgical facemask under compared to over an oxygen (O2) mask are unclear. DESIGN: Single-center, comparative pilot study. Setting. Endoscopy procedure room at a major academic hospital. SUBJECTS: Five healthy anesthesiologists. Interventions. Using a carbon dioxide (CO2) sampling line positioned at the lips, the fraction of inspired O2 (FiO2), fraction of expiratory O2 (FeO2), expiratory end-tidal CO2 (EtCO2), and respiratory rate (RR) were measured under the following conditions: (1) a surgical facemask only, (2) a surgical facemask under an O2 mask, (3) an O2 mask only, and (4) a surgical facemask over an O2 mask. Measurements and Main Results. The sampled fractional expired oxygen (FeO2) at the lips was significantly lower when the surgical facemask was under compared to when over the O2 mask (27.9± 1.68 vs. 49.9 ± 6.27, p = 0.001), while there was no significant difference in inspired oxygen (FiO2). The sampled expiratory EtCO2 was significantly higher when the surgical facemask was under the O2 mask compared to when over the O2 mask (28.3 ± 8.5 vs. 23.5 ± 7.6, p = 0.026). The RR was not significantly different when the surgical facemask was under compared to over the O2 mask. CONCLUSIONS: Effective oxygen delivery and ventilation was reduced (lower FeO2 and increased EtCO2) when a surgical facemask was placed under compared to over an O2 mask.
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INTRODUCTION: The risk of developing severe COVID-19 illness despite completing vaccination for patients who have previously received immunosuppressive therapy is unclear. CASE PRESENTATION: We present three patients who received rituximab for treatment of autoimmune disorders who subsequently developed severe COVID-19 pneumonia post-vaccination requiring intensive care unit admission and found to have undetectable B cells. DISCUSSION: While there have been concerns about the effectiveness of COVID-19 vaccines in this patient cohort, this is the first case series to report development of severe COVID-19 illness after completing vaccination in those who previously received rituximab. Guidelines for the optimal timing of COVID-19 vaccination in relation to immunosuppressive therapy have been recently published, albeit after many patients in this subpopulation have already been vaccinated. CONCLUSION: This case series brings attention to the limited humoral response to vaccines in patients treated with rituximab, highlights existing guidelines and their limitations, and raises future considerations about the potential benefits to testing vaccine responsiveness.