Hospital survival in case of severe COVID-19 involvement is often associated with residual fibrotic lung abnormalities, evidenced by pulmonary CT at the time of discharge, and lung function tests. Given the severe multisystemic damage typically suffered by these patients, several forms of pulmonary vascular impact (macro and micro embolism or inflammatory endothelitis with neo angiogenesis) have been reported; additionally, the severe inflammatory response can lead to anemia with a reduction in oxygen carrying capacity.
On the other hand, prolonged hospitalization often promotes profound deconditioning and muscle atrophy; there is also some concern that direct muscle damage may occur from the virus itself.
Thus, in Milan, Italy, took place a study to evaluate if hospital discharged COVID-19 patients could perform exercise. The study enrolled 18 clinically healed COVID-19 patients that matched 18 control subjects for age, sex, and BMI.
Enrolled participants underwent spirometry, echocardiography at rest, cardiopulmonary stress test, and exercise stress echocardiography. Recovered COVID-19 patients were also taken samples for arterial gases at rest and during exertion.
Condensed by Claudio López Bruzual, MD.
Interesting data about COVID-19
Cardiorespiratory function at rest. Post-COVID-19 patients showed relatively lower lung volumes compared to control subjects, with an average decrease in FVC of 22% and FEV1 of 26%. Additional findings in recovered COVID-19 patients included:
- Their respiratory dynamics were characterized by higher respiratory rate (24 18.5), with higher end‐inspiratory lung volume (1.97 vs. 1.06).
- A slightly lower O2 saturation, albeit within the normal range.
- The Arterial Blood Oxygen Content (CAO2) was lower, associated with lower levels of Hb.
- Arteriovenous O2 difference was significantly lower in post-COVID-19 patients, but peripheral O2 extraction at rest was not different between COVID‐19, and controls.
Resting echocardiography showed no substantial differences between the two groups, except for mild dilated right ventricle. Both, cardiac output, and pulmonary artery pressure (PAP) were significantly higher in post-COVID-19 patients to that of controls, with similar total pulmonary resistances (TPR) in both groups.
Cardiorespiratory function during exercise. At peak exercise effort, consumption of VO2 was significantly lower in post-COVID-19 patients than that of controls. 95% of postCOVID-19 subjects had a reduced capacity of exercise with a peak VO2 less than 70% of predicted in 61% of patients. The VO2/work slope was also significantly lower than that of controls.
Oxygen delivery during exercise. Ventilation during exercise was lower in recovered patients than that of controls; the first ones had lower Tidal Volumes (TVs) and higher respiratory frequencies than that of controls.
Conclusions
This paper offers the first description of cardiorespiratory adaptation to exercise during the recovery phase of COVID-19 pneumonia. The findings so far include:
Patients recovering from COVID-19 pneumonia experience a significant reduction in exercise capacity.
Impairment in functional capacity is primarily related to peripheral factors (such as anemia and impaired O₂ extraction), rather than cardiac or respiratory limitations.
Despite severe lung damage, pulmonary vascular function does not appear to be significantly impaired.
Exercise hyperventilation after COVID-19 is mainly due to enhanced chemoreflex sensitivity, rather than an increased dead space to tidal volume ratio (VD/VT).
VO₂ at peak exercise (equivalent to VO₂ max in submaximal stress tests) is reduced by 30% in post-COVID-19 patients. This study provides evidence suggesting the absence of significant respiratory impairment in these patients. The observed changes appear to be due to reduced oxygen content and extraction, secondary to anemia and myopathic changes—possibly caused by medications or direct muscle toxicity from the virus. Spirometry follow up of FVC and FEV1 can be useful in the assessment of the patient’s recovery.
The findings might help to reassure survivors from COVID‐19 on the benignity of residual symptoms in most cases.
COVID-19 Lung Monitoring: Accurate Spirometry with SpiroScout
Spirometry is an essential tool for carefully monitoring lung health, especially in post-COVID-19 patients. By accurately measuring lung function, it allows healthcare providers to track disease progression and recovery, helping to make informed treatment decisions. Regular spirometry testing can be the key to ensuring your patients receive the best care possible as they recover and manage their lung health over time.
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