A study from the University of Oxford in the Journal of Applied Physiology in September 2022 investigated the effect of COVID-19 infection on the function of the lungs and respiratory system. The Department of Physiology, Anatomy, and Genetics led the study using a “novel computational approach”.
COVID-19
Although we are several years into the COVID-19 pandemic, with some suggesting that it is already over, little is understood about the consequences of COVID-19 infection. With time, research into Long COVID is exploring how this respiratory disease can leave its mark on patients well after the shorter-term symptoms have been overcome.
The study
The study involved 178 participants in 4 groups:
- The control group of participants who had not had COVID-19
- Patients who had COVID-19 and were managed in the community
- Those who were hospitalised with COVID-19 but not admitted to an intensive care unit (ICU)
- Those who were admitted to an ICU with severe COVID-19, often receiving invasive medical ventilation
Over 6 and 12 months following the initial infection the participants were studied with a novel computational approach. This approach is called computed cardiopulmonography (CCP). This involves breathing into a mouthpiece to a measuring device that uses lasers to measure gas composition. The measurements are “fed” into a computational model of the respiratory and cardiovascular systems to “estimate values for aspects relating to the individual’s lung function”. The model was adjusted to account for the individual’s physiological factors such as sex, age, and height.
Findings
The study reports that participants who required intensive care there was a “significant increase in anatomical deadspace” and a “significant increase in alveolar-to-arterial PO2 gradient” relative to controls. The key findings were summarised by the university as follows:
- Prior COVID-19 infection was associated with “more uneven inflation of the lungs during normal breathing”, which is part of normal ageing in the lung. However, the changes seen after COVID-19 in the study are “roughly equivalent to those associated with 15 years of normal ageing” but still smaller than those seen in “established lung disease”.
- The association between hospitalisation with COVID-19 and “smaller lung volumes” remains unknown. It could be that smaller volumes are caused by COVID-19 infection or “instead represent a predisposing factor for more severe infection”.
- Admission to the ICU was associated with an “enlarged respiratory deadspace”. This could have been caused by infection or the process of mechanical ventilation.
Dr Nayia Petousi is a Respiratory Consultant from the university’s Nuffield Department of Medicine and a clinical lead for the study. She hopes that these insights can “help in the clinical management of patients”. Lead author Professor Peter Robbins of the Department of Physiology, Anatomy, and Genetics said that the study “illustrates the capability of this new technique to study aspects of lung function not so easily measured through standard clinical tests”.
“However, without measurements prior to infection, it is not possible to conclude whether these differences result directly from COVID-19 infection, or whether they are actual risk factors associated with the lungs that predispose towards more serious disease.”
For more on the consequences of and responses to the COVID-19 pandemic come to the World Vaccine Congress in Barcelona 2022.
