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ORIGINAL RESEARCH article

Front. Physiol.
Sec. Respiratory Physiology and Pathophysiology
Volume 15 - 2024 | doi: 10.3389/fphys.2024.1399407

Body mass index is associated with pulmonary gas and blood distribution mismatch in COVID-19 acute respiratory failure. A physiological study

Provisionally accepted
Kristín Jóna Bjarnadóttir Kristín Jóna Bjarnadóttir 1*Gaetano Perchiazzi Gaetano Perchiazzi 1Caroline Sidenbladh Caroline Sidenbladh 2Aleksandra Larina Aleksandra Larina 1Ewa Wallin Ewa Wallin 1Ing-Marie Larsson Ing-Marie Larsson 1Stephanie Franzén Stephanie Franzén 1Anders Larsson Anders Larsson 1Mayson LA Sousa Mayson LA Sousa 3Monica Segelsjö Monica Segelsjö 1Tomas Hansen Tomas Hansen 1Robert Frithiof Robert Frithiof 1Michael Hultström Michael Hultström 1Miklos Lipcsey Miklos Lipcsey 1Mariangela Pellegrini Mariangela Pellegrini 1
  • 1 Uppsala University, Uppsala, Sweden
  • 2 Hudiksvall Hospital, Hudiksvall, Sweden
  • 3 University of Toronto, Toronto, Ontario, Canada

The final, formatted version of the article will be published soon.

    Background. The effects of obesity on pulmonary gas and blood distribution in patients with acute respiratory failure remain unknown. Dual-energy computed tomography (DECT) is a X-ray-based method used to study regional distribution of gas and blood within the lung.We hypothesized that 1) regional gas/blood mismatch can be quantified by DECT; 2) obesity influences the global and regional distribution of pulmonary gas and blood; 3) regardless of ventilation modality (invasive vs. non-invasive ventilation), patients' body mass index (BMI) has an impact on pulmonary gas/blood mismatch.Methods. This single-centre prospective observational study enrolled 118 hypoxic COVID-19 patients (92 male) in need of respiratory support and intensive care who underwent DECT. The cohort was divided into three groups according to BMI: 1. BMI<25kg/m 2 (non-obese), 2. BMI=25-40kg/m 2 (overweight to obese), and 3. BMI>40kg/m 2 (morbidly obese). Gravitational analysis of Hounsfield unit distribution of gas and blood was derived from DECT and used to calculate regional gas/blood mismatch. A sensitivity analysis was performed to investigate the influence of the chosen ventilatory modality and BMI on gas/blood mismatch and adjust for other possible confounders (i.e., age and sex).Results. 1) Regional pulmonary distribution of gas and blood and their mismatch were quantified using DECT imaging. 2) The BMI>40kg/m 2 group had less hyperinflation in the non-dependent regions and more lung collapse in the dependent regions compared to the other BMI groups. In morbidly obese patients, gas and blood were more evenly distributed; therefore, the mismatch was lower than in other patients (30% vs. 36%, P<0.05). 3) An increase in BMI of 5kg/m 2 was associated with a decrease in mismatch of 3.3% (CI: -3.67 to -2.93%, P<0.05). Neither the ventilatory modality nor age and sex affected the gas/blood mismatch (P>0.05).In a hypoxic COVID-19 population needing intensive care, pulmonary gas/blood mismatch can be quantified at a global and regional level using DECT. 2) Obesity influences the global and regional distribution of gas and blood within the lung, and BMI>40kg/m 2 improves pulmonary gas/blood mismatch. 3) This is true regardless of the ventilatory mode and other possible confounders, i.e., age and sex.

    Keywords: Ventilation/perfusion mismatch, mechanical ventilation, Obesity, Acute Respiratory Failure, COVID-19, dual-energy computer tomography Trial Registration: Clinicaltrials.gov identifier: NCT04316884, NCT04474249

    Received: 11 Mar 2024; Accepted: 30 May 2024.

    Copyright: © 2024 Bjarnadóttir, Perchiazzi, Sidenbladh, Larina, Wallin, Larsson, Franzén, Larsson, LA Sousa, Segelsjö, Hansen, Frithiof, Hultström, Lipcsey and Pellegrini. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Kristín Jóna Bjarnadóttir, Uppsala University, Uppsala, Sweden

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