The objective of this single-center retrospective observational study is to describe spirometric abnormalities and their impact on 6-minute walk test (6MWT) and the physical component summary (PCS) of the SF-36 quality of life instrument.at least 3 months later discharge hospital.

Background: The COVID-19 pandemic has already affected more than 400 million people worldwide and resulted in at least 6 million deaths. The disease has also resulted in a growing population of individuals, with both physical and mental sequelae. Pulmonary sequelae have been the subject of several studies because the lung is the main target organ of the disease. However, there is still unknown data about the pulmonary manifestations and their spirometric patterns after a critical illness and also its consequences in quality of life.

Purpose: Up to 20% of COVID-19 patients develop severe forms of the disease and require ICU admission. Most of these patients at hospital discharge still have several limitations that impact on quality of life. Some studies have analyzed pulmonary functional alterations after a variable period of time and have found results that vary from the absence of functional alterations to restrictive and diffusion impairment. Few studies have analyzed changes in small airways, and those that have evaluated have found no changes. The objective of this single-center retrospective observational study is to describe spirometric abnormalities and their impact on 6-minute walk test (6MWT) and the physical component summary (PCS) of the SF-36 quality of life instrument.at least 3 months later discharge hospital.

Primary outcome: To describe spirometric patterns associated to severe COVID-19 survivors at least 3 months after hospital discharge.

Secondary outcomes: Correlate the results of the spirometric evaluation with the 6-minute walk test (6MWT) and the physical component summary (PCS) of the SF-36 quality of life instrument.

Methods: An observational retrospective study will be conducted, including all 18 years and older patients with severe COVID-19, confirmed by real-time reverse transcriptase-polymerase chain reaction., admitted to a 35- bed intensive care unit of a tertiary hospital from April 2020 to October 2021. Pediatric, pregnant or breastfeeding women and palliative care patients as well as chronic obstructive pulmonary disease and symptomatic asthmatic patients will be excluded. Population is estimated at 60 patients. Data collecting will be finished in February 2022. Patients routinely are assessed after at least 3 months after hospital discharge in our multidisciplinary follow-up clinic. A trained research team will routinely apply the 6 minute walk test (6MWT), a Pulmonary Function Test (PFT) and Short Form Health Survey 36 (SF-36) physical component summary (PCS) of SF-36

Inclusion Criteria

• All 18 years and older patients with severe COVID-19, confirmed by real-time reverse transcriptase-polymerase chain reaction., admitted to a 15- bed intensive care unit of a tertiary hospital from April 2020 to October 2021.

Exclusion criteria

• < 18 years old
• Pregnant
• Breastfeeding
• Chronic pulmonary obstructive disease
• Symptomatic asthma

Patients with confirmed COVID-19 admitted to the ICU requiring non-invasive or invasive respiratory support