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The kinetics of IgG antibodies after coronavirus disease 2019 (COVID‐19) remain poorly understood. We investigated factors influencing severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) IgG antibody levels and time to seronegativation during the follow‐up of severe and critically ill patients. We retrospectively reviewed serological evaluations drawn during the follow‐up of severe or critical laboratory‐proven COVID‐19 patients hospitalized at a large academic hospital. Specific IgG titers were measured using a chemiluminescent assay targeting anti‐spike and anti‐nucleocapsid protein IgG. The influence of time, demographic factors, clinical and paraclinical characteristics, and COVID‐19 therapeutics on IgG levels were assessed through linear regression using a mixed‐effect model, and delay until IgG negativation through a Weibull regression model. The cohort included 116 patients with a total of 154 IgG measurements drawn at a median of 79 days after diagnosis. IgG antibodies were increased with age (p = 0.005) and decreased significantly over time (p = 0.0002). Using elapsed time and age as covariates, we demonstrated higher IgG levels in patients with a higher body mass index (BMI) (p = 0.0026) and lower IgG levels in immunocompromised patients (p = 0.032). A high BMI was further found to delay and immunodeficiency to hasten significantly seronegativation, whereas no significant effect was observed with corticosteroids. These data highlight the waning over time of IgG antibodies after severe or critical COVID‐19. Age, BMI, and immunosuppression also appear to influence the IgG kinetics, while short‐term corticotherapy does not. Those data improve the understanding of SARS‐CoV‐2 serology while further research should determine the determinants of long‐term seroprotection., Highlights Anti‐SARS‐CoV‐2 IgG antibody levels measured during follow‐up of severe and critical COVID‐19 were studied. We analyzed the influence of time, demographics, clinical and paraclinical characteristics and COVID‐19 treatments on specific IgG levels and time to seronegativation. Time and immunodepression were associated to reduced IgG levels at follow‐up, while age and BMI were associated to increased levels. Corticosteroids given as short‐term treatment for COVID‐19 did not show influence. BMI and immunodepression were respectively associated with decreased and increased rates of seronegativation.

INTRODUCTION: An increased prevalence of metabolic disorders and cardiovascular (CV) disease has been reported in childhood acute lymphoblastic leukaemia (ALL) / Non-Hodgkin lymphoma (NHL) cancer survivors. OBJECTIVE: To characterize the determinants of insulin resistance (IR) observed in this population, according to the treatment received. METHODS: 91 patients (45 men, mean age: 24 ± 5 years; mean follow-up: 15 ± 5 years) previously treated for a childhood ALL (n=76) or NHL (n=15) were grouped according to their previous treatment: chemotherapy only (Group I; n=43), chemotherapy + cranial irradiation (CI) (Group II; n=32) and chemotherapy + bone marrow transplant (BMT) / total body irradiation (TBI) (Group III, n=16). RESULTS: A high prevalence of IR (HOMA-S < 60%) was observed in the BMT/TBI group (88%) compared to groups I (9%) and II (16%). The IR patients from groups [I+II] (12% of these groups) showed higher BMI, fat mass (FM) and visceral fat when compared with the non-IR patients. In contrast, the IR patients from group III had mean BMI and total FM similar to those of non-IR patients but showed a reduction of lean body mass and an increase in the relative proportion of trunk FM similar to the IR patients from groups [I+II]. This was associated with an altered lipid profile, high TNF-α and IL-6 levels, and reduced adiponectin levels compared to IR patients from group [I+II] and non-IR patients. CONCLUSION: Childhood ALL/NHL survivors treated by BMT/TBI frequently develop severe insulin resistance associated with peripheral-to-central fat redistribution, rather than increased total FM, and low adiponectin levels which may contribute to their increased CV risk. © 2012 Blackwell Publishing Ltd.

Volumetric capnography provides a breath-by-breath analysis of ventilation-perfusion imbalances and deadspace volumes. The technique has been best described in intubated and ventilated patients, but promising clinical applications also concern spontaneously breathing patients. The objective of the study was to verify the reliability and reproducibility of a new capnographic program in various types of clinical conditions. In a first step, 56 patients, either healthy or with acute respiratory disorders, were connected to a sidestream gas sampler and flow sensor through a mouthpiece. An acquisition software synchronized expired CO2 and flow data to create volumetric capnographic curves. Mixed expired CO2 partial pressure, corresponding to the exhaled CO2 of the effective tidal volume, was simultaneously collected in a neoprene bag for comparison. In a second step, changes in airway deadspace before and after the adjunction of known spacer volumes were compared in six healthy volunteers. The mean difference between both methods in measuring mixed expired CO2 partial pressure was -0.9 mmHg (SE 0.2 mmHg, P