High-flow Nasal Cannula Research Articles

The impact of pulmonary tuberculosis on SARS-CoV-2 infection: a nationwide cohort study.

The interaction between COVID-19 and tuberculosis (TB) is not yet fully understood, and large-scale research on the mortality outcome of such dual infection has been limited. This study aimed to investigate the impact of PTB on mortality among patients with COVID-19 within a Korean population by conducting an extensive analysis of a nationwide large dataset. We investigated the mortality and disease severity among COVID-19 patients who had PTB in South Korea. This study analyzed 462,444 out of 566,494 COVID-19 patients identified between January 2020 and December 2021. A total of 203 COVID-19 with PTB patients and 812 matched COVID-19 without PTB were analyzed using 1:4 propensity score matching. COVID-19 patients with PTB exhibited higher in-hospital mortality (odds ratio (OR) 3.02, 95% confidence interval (CI) 1.45-6.27, p-value = 0.003) and were at increased risk of requiring conventional oxygen therapy (OR 1.57, 95% CI 1.10-2.25, p-value = 0.013) as well as high flow nasal cannula (HFNC) or noninvasive ventilation (NIV) oxygen therapy (OR 1.91, 95 CI 1.10-3.32, p-value = 0.022) compared to those without PTB. Compared to matched COVID-19 without PTB, co-infected patients showed increased mortality rates across various timeframes, including during hospitalization, and at 30 day and 90 day intervals. In-hospital mortality rates were particularly elevated among women, individuals with malignancy, and those with lower incomes. Furthermore, the increased in-hospital mortality among PTB patients persisted irrespective of the timing of TB diagnosis or vaccination status against COVID-19. We suggest that physicians be aware of the risk of mortality and severity among COVID-19 patients with PTB; coinfection with COVID-19 is a critical situation that remains to be further explored and needs more attention in countries with an intermediate to high PTB burden.

H1N1pdm09 infection in children: A case report of reemerging disease in COVID-19 pandemic

An outbreak of H1N1 infection was first declared by the World Health Organization in 2009 and confirmed in the post-pandemic phase in 2010. Amid the COVID-19 pandemic, we found a confirmed case of H1N1pdm09 in Bunda Women and Children Hospital Jakarta. A 13-year-old boy was referred to our hospital after four days of hospitalization due to worsening tachypnea following a productive cough and fever. The patient had severe dyspnea with inspiratory effort and oxygen desaturation to 80%, therefore admitted to our pediatric intensive care unit. On physical examination, the patient had increased work of breathing, looked irritable, had a respiratory rate of about 40x/minute with non-rebreathing mask support, and crackles were heard in both lungs. Chest x-ray showed right bronchopneumonia. There was a history of a generalized seizure for less than 1 minute, which stopped spontaneously in previous hospital care. The patient was diagnosed with mucopolysaccharidosis at age six years old and has never received enzyme replacement therapy. Laboratory results revealed thrombocytopenia, leukopenia, neutrophilia, monocytosis, high c-reactive protein and procalcitonin, and elevated liver enzymes. The investigation of etiology was performed using the respiratory panel test and showed a positive real-time polymerase chain reaction for H1N1pdm09 and Influenza A. The patient was given oxygen therapy with a high-flow nasal cannula with an oxygen fraction of 40% and a flow of 20 liters per minute, fluid maintenance while fasting, antibiotics, inhaled beta-2 agonists, and a neuraminidase inhibitor (oseltamivir). The patient's clinical and laboratory markers improved on the third day of treatment, and he was discharged two days later.

High-flow nasal cannula in Spanish Pediatric Intensive Care Services: A national web survey about its use and indications

ObjectiveTo describe the high-flow nasal cannula (HFNC) indications in the Spanish pediatric critical care units (PICUs). DesignDescriptive cross-sectional observational study. SettingElectronic survey among members of the Spanish Society of Pediatric Intensive Care (SECIP). It was sent weekly from April 10, 2023, to May 21, 2023. ParticipantsAll SECIP members. InterventionsNone. Main variables of interestThe questions focused on workplace, years of experience, use or non-use of HFNC, justification and expectations regarding its application, starting point within each center, clinical criteria for indication, existence of clinical guidelines, evaluation during its use, and criteria and mode of withdrawal. ResultsTwo hundred and two participants, 176 were from Spain. Of these, 87/176 had over ten years of experience. One hundred sixty two use HFNC and 66/162 have HFNC clinical guidelines. Acute bronchiolitis (138/162) and respiratory assistance after extubation (106/56) are the two main indications. For 62/162 HFNC may reduce therapeutic escalation. Neuromuscular diseases (105/162) and anatomical airway diseases (135/162) are the two main contraindications. The reasons to do not use HFNC were the absence of evidence about it effectiveness (8/14) and its inadequate cost/effectiveness balance (8/14). ConclusionsA majority of Spanish pediatric intensivists use HFNC. Its application and withdrawal appears to be primarily based on clinical experience. Besides, those who use HFNC are aware of its limitations and the lack of evidence in some cases. It is necessary to develop single-center and multicenter studies to elucidate the effectiveness of this therapy in the context of critically ill children.

The effect of in-bed cycling combined with high flow nasal cannula treatment on arterial oxygen and respiratory dynamics in patients with severe respiratory failure: A retrospective study.

To assess the effects of in-bed cycling (IBC) combined with high flow nasal cannula (HFNC) on arterial oxygen and respiratory dynamics in patients with severe respiratory failure (RF). We retrospectively collected clinical data of 103 patients with severe RF, admitted to the intensive care unit (ICU) of The Second Affiliated Hospital of Harbin Medical University from March 2021 to March 2023. Among them, 50 patients had HFNC alone (control group), and 53 patients did IBC in addition to HFNC (observation group). We compared arterial oxygen index, lung function, respiratory dynamics, and clinical efficacy between the two groups. There was no significant difference in the basic data between the two groups (P>0.05). After the treatment, the improvement of the partial pressure of oxygen (PaO2), PaO2/fraction of inspired oxygen (FiO2), arterial oxygen saturation (SaO2), and oxygen delivery (DO2) in the observation group was significantly better than that in the control group (P<0.05). After the treatment, the improvement of lung function in the observation group was better than that in the control group (P<0.05). After the treatment, the end expiratory pulmonary pressure (Ptp-ee) and driving pressure (△Ptp) levels in the observation group were significantly higher, and the duration of ICU hospitalization and the incidence of ICU-acquired weakness(ICU-AW) were significantly lower than those in the control group (P<0.05). IBC combined with HFNC can significantly improve arterial oxygen levels, lung function, and respiratory dynamics in patients with severe RF. IBC in combination with HFNC is associated with shorter stay time in the ICU, reduced of ICU-acquired weakness, and better physical recovery of patients.

Exploring Heterogeneity in the Cost-Effectiveness of High-Flow Nasal Cannula Therapy in Acutely Ill Children—Insights From the Step-Up First-line Support for Assistance in Breathing in Children Trial Using a Machine Learning Method

ObjectivesTo investigate heterogeneity in the cost-effectiveness of high-flow nasal cannula (HFNC) therapy compared with continuous positive airway pressure (CPAP) for acutely ill children requiring noninvasive respiratory support. MethodsUsing data from the First-line Support for Assistance in Breathing in Children trial, we explore heterogeneity at the patient and subgroup levels using 2 causal forest approaches and a seemingly unrelated regression approach for comparison. First-line Support for Assistance in Breathing in Children is a noninferiority randomized controlled trial (ISRCTN60048867) involving 24 UK pediatric intensive care units. The Step-up trial focuses on acutely ill children aged 0 to 15 years, requiring noninvasive respiratory support. A total of 600 children were randomly assigned to HFNC and CPAP groups in a 1:1 allocation ratio, with 94 patients excluded because of data unavailability. ResultsThe primary outcome is the incremental net monetary benefit (INB) of HFNC compared with CPAP, using a willingness-to-pay threshold of £20 000 per quality-adjusted life year gain. INB is derived from total costs and quality-adjusted life years at 6 months. Subgroup analysis showed that some subgroups, such as male children, those aged less than 12 months, and those without severe respiratory distress at randomization, had more favorable INB results. Patient-level analysis revealed heterogeneity in INB estimates, particularly driven by the cost component, with greater uncertainty for those with higher INBs. ConclusionsThe estimated overall INB of HFNC is significantly larger for specific patient subgroups, suggesting that the cost-effectiveness of HFNC can be heterogeneous, which highlights the importance of considering patient characteristics in evaluating the cost-effectiveness of HFNC.

61 Rapid sequence induction of anaesthesia: standard procedure vs. high flow nasal oxygen (HFNO)

61 Rapid sequence induction of anaesthesia: standard procedure vs. high flow nasal oxygen (HFNO)

Human Bocavirus related lower respiratory tract infection in childhood: A case report

Human Bocavirus (HBoV) may cause lower respiratory infections (RTIs). In some studies, it is the third most common pathogen in children with lower respiratory tract infections. In this study, we report a 3 year-5 month-old age girl with fever, cough and rhinorrhea caused by HBoV. HBoV was detected in the patient whose nasopharyngeal aspirate (NPA) was tested by qualitative multiplex polymerase chain reaction (PCR), as her general condition worsened, a high-flow nasal cannula was applied, as well as intravenous antibiotics and inhaler drugs. Human bocavirus can be responsible as a viral agent in children with respiratory tract infections during fall and winter months. It should be kept in mind the use of the nasopharengeal aspirates by qualitative multiplex PCR as a diagnostic test may enable more patients to be diagnosed.

Ward Weight-based High Flow Nasal Cannula Treatment

Ward Weight-based High Flow Nasal Cannula Treatment

26 Optimizing High Flow Nasal Cannula in patient with respiratory failure to improve oxygenation thus avoiding escalation to more invasive support in KFAFH – Jeddah

26 Optimizing High Flow Nasal Cannula in patient with respiratory failure to improve oxygenation thus avoiding escalation to more invasive support in KFAFH – Jeddah

Comparison of Modified ROX Index Score and ROX Index Score for Early Prediction of High Flow Nasal Oxygen Therapy Outcome in Patients with Acute Respiratory Failure: A Prospective Observational Cohort Study.

We compared the modified ROX index and ROX index scores in earlier predictions of high-flow nasal oxygen (HFNO) therapy outcomes in patients with acute respiratory failure. We conducted a prospective observational study on 151 acute respiratory failure patients initiated on HFNO therapy. The primary objective of this research was to compare the modified ROX index and ROX index to investigate which score predicted HFNO treatment outcome earlier. The modified ROX index score had better predictive power than the ROX score at different time points, especially one hour following the start of HFNO therapy (AUC 0.790; 95% CI: 0.717-0.863; p < 0.001). For the ROX Index at 1 hour, the ideal cut-off value for HFNO outcome was 4.36 (sensitivity: 72.6%, specificity: 53.9%), and for the modified ROX index at 1 hour, it was 4.63 (sensitivity: 74.2%, specificity: 69.7%). The presence of various comorbidities didn't show any change in ROX-HR cut-off values. The modified ROX index is a better predictor of the success of HFNO therapy than the ROX index. Furthermore, the presence of any comorbidities did not affect modified ROX index cut-off values or the outcome of HFNO therapy. Sarkar AG, Sharma A, Kothari N, Goyal S, Meshram T, Kumari K, et al. Comparison of Modified ROX Index Score and ROX Index Score for Early Prediction of High Flow Nasal Oxygen Therapy Outcome in Patients with Acute Respiratory Failure: A Prospective Observational Cohort Study. Indian J Crit Care Med 2024;28(9):842-846.

Adenoviral infection in children admitted with severe acute respiratory infection at tertiary care hospital from North India: A case series

Abstract There has been a recent surge in adenoviral infections with poor outcomes. This case series describes the clinical profile and outcome of 38 children admitted with adenovirus infection with severe acute respiratory illness (SARI). The majority (68.4%) were infants, 25 (65.7%) were immunocompetent, and 13 (34.2%) had an underlying comorbidity. Twenty-seven (71%) patients required mechanical ventilation and 5 (13.1%) were managed on a heated high-flow nasal cannula. Nine (23.6%) children developed acute respiratory distress syndrome and four (10.5%) cases developed postinfectious bronchiolitis obliterans (PIBO). The median duration of mechanical ventilation was 24 days interquartile range [11.5–34.5] days. Eleven (28.9%) children in the study population expired.

The clinical characteristics associated with the ratio between the main pulmonary artery and ascending aorta diameter in patients with acute exacerbation of chronic obstructive pulmonary disease.

A pulmonary artery-to-aorta (PA/A) ratio of ≥1 is a reliable indicator of pulmonary hypertension and is associated with an increased risk of acute exacerbation of chronic obstructive pulmonary disease (COPD) and long-term mortality in patients with stable COPD. However, it is unclear whether a PA/A ratio of ≥1 is associated with mortality in patients hospitalized with acute exacerbation of COPD. The purpose of this study was to evaluate the clinical course and mortality of patients with PA/A ratios of ≥1 who were hospitalized with acute exacerbation of COPD. We retrospectively reviewed the medical charts of patients admitted to a tertiary referral hospital and a secondary hospital with acute exacerbation of COPD between 2016 and 2021. Chest computed tomography was used to measure the pulmonary artery (PA), aorta (A) diameter, and the PA/A ratio. The study involved 324 and 111 patients with PA/A ratios <1 and ≥1, respectively. The average age in the two groups was 74.1 and 74.5 years, which was not significantly different. When compared with the group with PA/A ratios of <1, the group with PA/A ratios of ≥1 had a lower proportion of males (71.2% vs. 89.5%, P<0.001), more patients with type 2 respiratory failure (35.1% vs. 18.8%), higher high-flow nasal cannula use (10.8% vs. 4.6%), higher use of non-invasive ventilation (NIV) (21.6% vs. 7.7%), and longer hospital stay (10.9 vs. 9.5 days). In-hospital mortality was not significantly different between the two groups. A PA/A ratio of ≥1 was identified as an independent predictor of the need for high-flow nasal cannula, NIV, and intubation in COPD patients. Patients with PA/A ratios of ≥1 had a high incidence of type 2 acute respiratory failure and required advanced treatment, including high-flow nasal cannula, NIV, and intubation. Therefore, hospitalized patients with acute exacerbation of COPD and PA/A ratios of ≥1 require more aggressive treatment.

Effect on post-operative pulmonary complications frequency of high flow nasal oxygen versus standard oxygen therapy in patients undergoing esophagectomy for cancer: study protocol for a randomized controlled trial-OSSIGENA study.

Postoperative pulmonary complications (PPCs) remain a challenge after esophagectomy. Despite improvement in surgical and anesthesiological management, PPCs are reported in as many as 40% of patients. The main aim of this study is to investigate whether early application of high-flow nasal cannula (HFNC) after extubation will provide benefit in terms of reduced PPC frequency compared to standard oxygen therapy. Patients aged 18-85 years undergoing esophagectomy for cancer treatment with radical intent, excluding those with American Society of Anesthesiologists (ASA) score >3 and severe systemic comorbidity (cardiac, pulmonary, renal or hepatic disease) will be randomized at the end of surgery to receive HFNC or standard oxygen therapy (Venturi mask or nasal goggles) after early extubation (within 12 hours after the end of surgery) for 48 hours. The main postoperative goals are to obtain SpO2 ≥94% and adequate pain control. Oxygen therapy after 48 hours will be stopped unless the physician deems it necessary. In case of respiratory clinical worsening, patients will be supported with the most appropriate tool (noninvasive ventilation or invasive mechanical ventilation). Pulmonary [pneumonia, pleural effusion, pneumothorax, atelectasis, acute respiratory distress syndrome (ARDS), tracheo-bronchial injury, air leak, reintubation, and/or respiratory failure] complications will be recorded as main outcome. Secondary outcomes, including cardiovascular, surgical, renal and infective complications will also be recorded. The primary analysis will be carried out on 320 patients (160 per group) and performed on an intention-to-treat (ITT) basis, including all participants randomized into the treatment groups, regardless of protocol adherence. The primary outcome, the PPC rate, will be compared between the two treatment groups using a chi-square test for categorical data, or Fisher's exact test will be used if the assumptions for the chi-square test are not met. Recent evidence demonstrated that early application of HFNC improved the respiratory rate oxygenation index (ROX index) after esophagectomy but did not reduce PPCs. This randomized controlled multicenter trial aims to assess the potential effect of the application of HFNC versus standard oxygen over PPCs in patients undergoing esophagectomy. This study is registered at clinicaltrial.gov NCT05718284, dated 30 January 2023.

Role of High flow Nasal Cannula Oxygen Therapy Versus Non-Invasive Ventilation in the Management of Acute Respiratory Failure

Role of High flow Nasal Cannula Oxygen Therapy Versus Non-Invasive Ventilation in the Management of Acute Respiratory Failure

A matched analysis of the use of high flow nasal cannula for pediatric severe acute asthma.

The high-flow nasal cannula (HFNC) device is commonly used to treat pediatric severe acute asthma. However, there is little evidence regarding its effectiveness in real-world practice. We sought to compare the physiologic effects and clinical outcomes for children treated for severe acute asthma with HFNC versus matched controls. This was a single-center retrospective matched cohort study at a quaternary care children's hospital. Children ages 2-18 hospitalized for severe acute asthma from 2015 to 2022 were included. Encounters receiving treatment with HFNC within the first 24 h of hospitalization were included as cases. Controls were primarily treated with oxygen facemask. Logistic regression 1:1 propensity score matching was done using demographics, initial vital signs, and medications. The primary outcome was an improvement in clinical asthma symptoms in the first 24 h of hospitalization measured as percent change from initial. Of 693 eligible cases, 443 were matched to eligible controls. Propensity scores were closely aligned between the cohorts, with the only significant difference in clinical characteristics being a higher percentage of patients of Black race in the control group (54.3% vs. 46.6%; p = 0.02). Compared to the matched controls, the HFNC cohort had smaller improvements in heart rate (-11.5% [-20.9; -0.9] vs. -14.7% [-22.6;-5.7]; p < 0.01), respiratory rate (-14.3% [-27.9;5.4] vs. -16.7% [-31.5;0.0]; p = 0.03), and pediatric asthma severity score (-14.3% [-28.6;0.0] vs. -20.0% [-33.3;0.0]; p < 0.01) after 24 h of hospitalization. The HFNC cohort also had longer pediatric intensive care unit (PICU) length of stay (LOS) (1.5 days [1.1;2.1] vs. 1.2 days [0.9;1.8]; p < 0.01) and hospital LOS (2.8 days [2.1;3.8] vs. 2.5 days [1.9;3.4]; p < 0.01). When subgrouping to younger patients (2-3 years old), or those with the highest severity scores (PASS > 9), those treated with HFNC had no difference in clinical symptom improvements but maintained a longer PICU LOS. Encounters using HFNC for severe acute pediatric asthma had decreased clinical improvement in 24 h of hospitalization compared to matched controls and increased LOS. Specific subgroups of younger patients and those with the highest severity scores showed no differences in clinical symptom improvement suggesting differential effects in specific patient populations.

Heated Humidified High Flow Nasal Cannula for Non-Invasive Primary Respiratory Support in Neonates: Experience of a Referral Neonatal Level III Facility in South-South Nigeria

Background: Heated humidified high flow nasal cannula (HHHFNC) is an increasingly used tool for non-invasive ventilation (NIV) in neonates and children needing advanced respiratory support.1 In neonates, common indications for HHHFNC therapy include: respiratory distress syndrome (RDS), post extubation from mechanical ventilation; and other causes of respiratory distress. Its use in Nigeria is not widespread. The aim of this study is to assess the indications, clinical characteristics, outcome and determinants of the successful use of HHHFNC for providing primary respiratory support for neonates referred and needing NIV in a Level III NICU in Nigeria. Methods: This was a retrospective study. All neonates in this study were referred to our facility, Med-Vical Medical Centre, Benin City, Edo State, Nigeria and received HHHFNC for primary respiratory support. Results: The highest indication for primary use of HHHFNC for neonates was respiratory distress syndrome (50.0%). The success rate of HHHFNC in this study was high (70.0%). Although not statistically significant, a higher proportion of neonates in the failure group weighed less than 1kg, while in the successful group, a higher proportion was delivered after 28 weeks. All infants who stayed longer than 7days on admission belonged to the successful group, and none failed HHHFNC therapy. This difference was statistically significant (p=0.011). In conclusion, this study revealed that the success rate of HHHFNC therapy as primary respiratory support in neonates with respiratory distress is high (70.0%), thus it can be used confidently in neonates needing NIV. Length of hospital stay was the only significant factor associated with the successful use of HHHFNC as primary respiratory support.

Monitoring and modulation of respiratory drive in patients with acute hypoxemic respiratory failure in spontaneous breathing.

Non-invasive respiratory support, namely, non-invasive ventilation, continuous positive airway pressure, and high-flow nasal cannula, has been increasingly used worldwide to treat acute hypoxemic respiratory failure, giving the benefits of keeping spontaneous breathing preserved. In this scenario, monitoring and controlling respiratory drive could be helpful to avoid patient self-inflicted lung injury and promptly identify those patients that require an upgrade to invasive mechanical ventilation. In this review, we first describe the physiological components affecting respiratory drive to outline the risks associated with its hyperactivation. Further, we analyze and compare the leading strategies implemented for respiratory drive monitoring and discuss the sedative drugs and the non-pharmacological approaches used to modulate respiratory drive during non-invasive respiratory support. Refining the available techniques and rethinking our therapeutic and monitoring targets can help critical care physicians develop a personalized and minimally invasive approach.

Effect of high-flow nasal and buccal oxygenation on safe apnea time in children with open mouth: A randomized controlled trial.

High-flow nasal oxygenation is reported to prolong duration of apnea while maintaining adequate oxygen saturation with the mouth closed. Also, buccal oxygenation is known to have similar effects in obese adults. We compared the effect of these two methods on prolongation of acceptable apnea time in pediatric patients with their mouth open. Thirty-eight patients, aged 0-10 years were randomly allocated to either the high-flow nasal oxygenation group (n = 17) or the buccal oxygenation group (n = 21). After induction of anesthesia including neuromuscular blockade, manual ventilation was initiated until the expiratory oxygen concentration reached 90%. Subsequently, ventilation was paused, and the patient's head was extended, and mouth was opened. The HFNO group received 2 L·min-1·kg-1 of oxygen, and the BO group received 0.5 L·min-1·kg-1 of oxygen. We set a target apnea time according to previous literature. When the apnea time reached the target, we defined the case as "success" in prolongation of safe apnea time and resumed ventilation. When the pulse oximetry decreased to 92% before the target apnea time, it was recorded as "failure" and rescue ventilation was given. The success rate of safe apnea prolongation was 100% in the high-flow nasal oxygenation group compared to 76% in the buccal oxygenation group (p = .04). Oxygen reserve index, end-tidal or transcutaneous carbon dioxide partial pressure, and pulse oximetry did not differ between groups. High-flow nasal oxygenation is effective in maintaining appropriate arterial oxygen saturation during apnea even in children with their mouth open and is superior to buccal oxygenation. Buccal oxygenation may be a good alternative when high-flow nasal oxygenation is not available.

Predictors of high-flow nasal cannula failure in COVID-19 patients in a northern Peruvian hospital

ObjectivesTo determine predictors of high-flow nasal cannula (HFNC) failure in COVID-19 patients in a hospital in northern Peru.MethodologyA retrospective cohort study was conducted during the months of March and May 2021. Data collection was based on a follow-up of 156 hospitalized patients with a diagnosis of COVID-19 who were users of HFNC. Epidemiological factors and clinical outcomes of treatment were analyzed from medical records. Epidemiological, analytical, and HFNC use-related characteristics were described using measures of absolute and relative frequencies, measures of central tendency, and dispersion. A multivariate Poisson regression analysis with robust variance and a 95% confidence interval was performed.ResultsWe found that age, SpO2/FiO2, work of breathing (WOB scale) at admission, degree of involvement, type of infiltrate on CT scan, lymphocytes, c-reactive protein, and D-dimer were significantly associated with failure of HFNC (p < 0.05). In addition, the WOB scale, PaO2/FiO2, SaO2/FiO2, and ROX index were variables that presented statistical significance (p < 0.0001). In the multivariate analysis model, a risk of failure of HFNC was determined with age > = 60 years [RRa 1.39 (1.05–1.85)] and PaO2/FiO2 score less than 100 [Rra 1.65 (0.99–2.76)].ConclusionsPredictors to failure of HFNC are age older than 60 years and minimally significantly lower PaO2/FiO2 than 100.

Post-COVID Interstitial Lung Disease: How do We Deal with This New Entity?

In the postacute phase of coronavirus disease-2019 (COVID-19), survivors may have persistent symptoms, lung function abnormalities, and sequelae lesions on thoracic computed tomography (CT). This new entity has been defined as post-COVID interstitial lung disease (ILD) or residual disease. To evaluate the characteristics, risk factors and clinical significance of post-COVID ILD. Multicenter cross-sectional analysis of data from a randomized clinical study. In this study, patients with persistent respiratory symptoms 3 months after recovery from COVID-19 were evaluated by two pulmonologists and a radiologist. post-COVID ILD was defined as the presence of respiratory symptoms, hypoxemia, restrictive defect on lung function tests, and interstitial changes on follow-up high-resolution computed tomography (HRCT). At the three-month follow-up, 375 patients with post-COVID-19 syndrome were evaluated, and 262 patients were found to have post-COVID ILD. The most prevalent complaints were dyspnea (n = 238, 90.8%), exercise intolerance (n = 166, 63.4%), fatigue (n = 142, 54.2%), and cough (n = 136, 52%). The mean Medical Research Council dyspnea score was 2.1 ± 0.9, oxygen saturation was 92.2 ± 5.9%, and 6-minute walking distance was 360 ± 140 meters. The mean diffusing capacity of the lung for carbon monoxide was 58 ± 21, and the forced vital capacity was 70% ± 19%. Ground glass opacities and fibrotic bands were the most common findings on thoracic HRCT. Fibrosis-like lesions such as interlobular septal thickening and traction bronchiectasis were observed in 38.3% and 27.9% of the patients, respectively. No honeycomb cysts were observed. Active smoking [odds ratio (OR), 1.96; 95% confidence interval (CI), 1.44-2.67), intensive care unit admission during the acute phase (OR, 1.46; 95% CI, 1.1-1.95), need for high-flow nasal oxygen (OR, 1.55; 95% CI, 1.42-1.9) or non-invasive ventilation (OR, 1.31; 95% CI, 0.8-2.07), and elevated serum lactate dehydrogenase levels (OR, 1.23; 95% CI 1.18-1.28) were associated with the development of post-COVID ILD. At the 6-month follow-up, the respiratory symptoms and pulmonary functions had improved spontaneously without any specific treatment in 35 patients (13.4%). The radiological interstitial lesions had spontaneously regressed in 54 patients (20.6%). The co-existence of respiratory symptoms, radiological parenchymal lesions, and pulmonary functional abnormalities which suggest a restrictive ventilatory defect should be defined as post-COVID-19 ILD. However, the term “fibrosis” should be used carefully. Active smoking, severe COVID-19, and elevated lactate dehydrogenase level are the main risk factors of this condition. These post-COVID functional and radiological changes could disappear over time in 20% of the patients.