Evolution and long­term respiratory sequelae after severe COVID-19 pneumonia: nitric oxide diffusion measurement value.

INTRODUCTION: There are no published studies assessing the evolution of combined determination of the lung diffusing capacity for both nitric oxide and carbon monoxide (DLNO and DLCO) 12 months after the discharge of patients with COVID-19 pneumonia. METHODS: Prospective cohort study which included patients who were assessed both 3 and 12 months after an episode of SARS-CoV-2 pneumonia. Their clinical status, health condition, lung function testings (LFTs) results (spirometry, DLNO-DLCO analysis, and six-minute walk test), and chest X-ray/computed tomography scan images were compared. RESULTS: 194 patients, age 62 years (P25-75, 51.5-71), 59% men, completed the study. 17% required admission to the intensive care unit. An improvement in the patients' exercise tolerance, the extent of the areas of ground-glass opacity, and the LFTs between 3 and 12 months following their hospital discharge were found, but without a decrease in their degree of dyspnea or their self-perceived health condition. DLNO was the most significantly altered parameter at 12 months (19.3%). The improvement in DLNO-DLCO mainly occurred at the expense of the recovery of alveolar units and their vascular component, with the membrane factor only improving in patients with more severe infections. CONCLUSIONS: The combined measurement of DLNO-DLCO is the most sensitive LFT for the detection of the long-term sequelae of COVID-19 pneumonia and it explain better their pathophysiology.

Lung diffusing capacity for nitric oxide and carbon monoxide following mild-to-severe COVID-19.

A decreased lung diffusing capacity for carbon monoxide (DLCO ) has been reported in a variable proportion of subjects over the first 3 months of recovery from severe coronavirus disease 2019 (COVID-19). In this study, we investigated whether measurement of lung diffusing capacity for nitric oxide (DLNO ) offers additional insights on the presence and mechanisms of gas transport abnormalities. In 94 subjects, recovering from mild-to-severe COVID-19 pneumonia, we measured DLNO and DLCO between 10 and 266 days after each patient was tested negative for severe acute respiratory syndrome coronavirus 2. In 38 subjects, a chest computed tomography (CT) was available for semiquantitative analysis at six axial levels and automatic quantitative analysis of entire lungs. DLNO was abnormal in 57% of subjects, independent of time of lung function testing and severity of COVID-19, whereas standard DLCO was reduced in only 20% and mostly within the first 3 months. These differences were not associated with changes of simultaneous DLNO /DLCO ratio, while DLCO /VA and DLNO /VA were within normal range or slightly decreased. DLCO but not DLNO positively correlated with recovery time and DLCO was within the normal range in about 90% of cases after 3 months, while DLNO was reduced in more than half of subjects. Both DLNO and DLCO inversely correlated with persisting CT ground glass opacities and mean lung attenuation, but these were more frequently associated with DLNO than DLCO decrease. These data show that an impairment of DLNO exceeding standard DLCO may be present during the recovery from COVID-19, possibly due to loss of alveolar units with alveolar membrane damage, but relatively preserved capillary volume. Alterations of gas transport may be present even in subjects who had mild COVID-19 pneumonia and no or minimal persisting CT abnormalities. TRIAL REGISTRY: ClinicalTrials.gov PRS: No.: NCT04610554 Unique Protocol ID: SARS-CoV-2_DLNO 2020.

Addressing Reduced Laboratory-Based Pulmonary Function Testing During a Pandemic.

To reduce the spread of the severe acute respiratory syndrome coronavirus 2, many pulmonary function testing (PFT) laboratories have been closed or have significantly reduced their testing capacity. Because these mitigation strategies may be necessary for the next 6 to 18 months to prevent recurrent peaks in disease prevalence, fewer objective measurements of lung function will alter the diagnosis and care of patients with chronic respiratory diseases. PFT, which includes spirometry, lung volume, and diffusion capacity measurement, is essential to the diagnosis and management of patients with asthma, COPD, and other chronic lung conditions. Both traditional and innovative alternatives to conventional testing must now be explored. These may include peak expiratory flow devices, electronic portable spirometers, portable exhaled nitric oxide measurement, airwave oscillometry devices, and novel digital health tools such as smartphone microphone spirometers and mobile health technologies along with integration of machine learning approaches. The adoption of some novel approaches may not merely replace but could improve existing management strategies and alter common diagnostic paradigms. With these options comes important technical, privacy, ethical, financial, and medicolegal barriers that must be addressed. However, the coronavirus disease 19 pandemic also presents a unique opportunity to augment conventional testing by including innovative and emerging approaches to measuring lung function remotely in patients with respiratory disease. The benefits of such an approach have the potential to enhance respiratory care and empower patient self-management well beyond the current global pandemic.

Follow up of patients with severe coronavirus disease 2019 (COVID-19): Pulmonary and extrapulmonary disease sequelae.

BACKGROUND: Since December 2019 the novel coronavirus disease 2019 (COVID-19) has been burdening all health systems worldwide. However, pulmonary and extrapulmonary sequelae of COVID-19 after recovery from the acute disease are unknown. MATERIAL AND METHODS: Hospitalized COVID-19 patients not requiring mechanical ventilation were included and followed 6 weeks after discharge. Body plethysmography, lung diffusion capacity (DLco), blood gas analysis (ABG), 6-min walk test (6MWT), echocardiography, and laboratory tests were performed. Quality of life (QoL), depression, and anxiety were assessed using validated questionnaires. RESULTS: 33 patients with severe disease were included. Patients were discharged without prophylactic anticoagulation. At follow-up there were no thromboembolic complications in any patient. 11 patients (33%) had dyspnea, 11 (33%) had cough, and 15 (45%) suffered from symptoms of fatigue. Pulmonary function tests including ABG did not reveal any limitations (TLC: median=94% of predicted {IQR:85-105}; VC: 93% {78-101}; FEV1: 95% {72-103}; FEV1/FVC 79% {76-85}; PaO2: 72 mmHg {67-79}; PaCO2: 38 mmHg {35-38}), except for slightly reduced DLco (77% {69-95}). There were no echocardiographic impairments. 6MWT distance was reduced in most patients without oxygen desaturation. According to standardized questionnaires, patients suffered from reduced QoL, mainly due to decreased mobility (SGRQ activity score: 54 {19-78}). There were no indicators for depression or anxiety (PHQ-9: 7 {4-11}, GAD-7: 4 {1-9}, respectively). CONCLUSIONS: Hospitalized patients with severe COVID-19, who did not require mechanical ventilation, are unlikely to develop pulmonary long-term impairments, thromboembolic complications or cardiac impairments after discharge but frequently suffer from symptoms of fatigue.