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EClinicalMedicine ; 39: 101066, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1372972


BACKGROUND: Dyspnea and exercise intolerance are commonly reported post-acute sequelae of SARS-CoV-2 infection (PASC), but routine diagnostic testing is often normal. Cardiopulmonary exercise testing (CPET) offers comprehensive assessment of dyspnea to characterize pulmonary PASC. METHODS: We performed a retrospective cohort study of CPET performed on patients reporting dyspnea and/or exercise intolerance following confirmed Covid-19 between August 1, 2020 and March 1, 2021, and compared them to age- and sex-matched patients with unexplained dyspnea referred for CPET at the same center in the pre-Covid-19 era. FINDINGS: Compared to matched unexplained dyspnea comparators, PASC patients shared similar medical comorbidities and subjective dyspnea at referral (mMRC score 1.6 ± 0.9 vs. 1.4 ± 0.9, P = 0.5). Fifteen (83.3%) PASC patients underwent high resolution computed tomography of the chest, of which half (46.7%) were normal, and 17 (94.4%) patients had pulmonary function testing, of which the majority (76.5%) were normal. All patients underwent CPET, and 12 (67%) had normal findings. Compared to matched comparators, PASC patients had similar peak oxygen consumption, oxygen consumption at ventilatory anaerobic threshold, and ventilatory efficiency measured by the minute ventilation to carbon dioxide production (VE/VCO2) slope. INTERPRETATION: Despite prominent dyspnea, physiological abnormalities on CPET were mild across a range of initial Covid-19 severity and similar to matched comparators referred for dyspnea without antecedent SARS-CoV-2. FUNDING: The project was supported by the NHLBI (R01HL131029, R01HL151841, U10HL110337, T32HL116275) and a KL2 award (5KL2TR002542-02) from Harvard Catalyst.

Crit Care Explor ; 3(6): e0471, 2021 Jun.
Article in English | MEDLINE | ID: covidwho-1276252


IMPORTANCE: Prone positioning improves clinical outcomes in moderate-to-severe acute respiratory distress syndrome and has been widely adopted for the treatment of patients with acute respiratory distress syndrome due to coronavirus disease 2019. Little is known about the effects of prone positioning among patients with less severe acute respiratory distress syndrome, obesity, or those treated with pulmonary vasodilators. OBJECTIVES: We characterize the change in oxygenation, respiratory system compliance, and dead-space-to-tidal-volume ratio in response to prone positioning in patients with coronavirus disease 2019 acute respiratory distress syndrome with a range of severities. A subset analysis of patients treated with inhaled nitric oxide and subsequent prone positioning explored the influence of pulmonary vasodilation on the physiology of prone positioning. DESIGN SETTING AND PARTICIPANTS: Retrospective cohort study of all consecutively admitted adult patients with acute respiratory distress syndrome due to coronavirus disease 2019 treated with mechanical ventilation and prone positioning in the ICUs of an academic hospital between March 11, 2020, and May 1, 2020. MAIN OUTCOMES AND MEASURES: Respiratory system mechanics and gas exchange during the first episode of prone positioning. RESULTS: Among 122 patients, median (interquartile range) age was 60 years (51-71 yr), median body mass index was 31.5 kg/m2 (27-35 kg/m2), and 50 patients (41%) were female. The ratio of Pao2 to Fio2 improved with prone positioning in 90% of patients. Prone positioning was associated with a significant increase in the ratio of Pao2 to Fio2 (from median 149 [123-170] to 226 [169-268], p < 0.001) but no change in dead-space-to-tidal-volume ratio or respiratory system compliance. Supine ratio of Pao2 to Fio2, respiratory system compliance, positive end-expiratory pressure, and body mass index did not correlate with absolute change in the ratio of Pao2 to Fio2 with prone positioning. However, patients with ratio of Pao2 to Fio2 less than 150 experienced a greater relative improvement in oxygenation with prone positioning than patients with ratio of Pao2 to Fio2 greater than or equal to 150 (median percent change in ratio of Pao2 to Fio2 62 [29-107] vs 30 [10-70], p = 0.002). Among 12 patients, inhaled nitric oxide prior to prone positioning was associated with a significant increase in the ratio of Pao2 to Fio2 (from median 136 [77-168] to 170 [138-213], p = 0.003) and decrease in dead-space-to-tidal-volume ratio (0.54 [0.49-0.58] to 0.46 [0.44-0.53], p = 0.001). Subsequent prone positioning in this subgroup further improved the ratio of Pao2 to Fio2 (from 145 [122-183] to 205 [150-232], p = 0.017) but did not change dead-space-to-tidal-volume ratio. CONCLUSIONS AND RELEVANCE: Prone positioning improves oxygenation across the acute respiratory distress syndrome severity spectrum, irrespective of supine respiratory system compliance, positive end-expiratory pressure, or body mass index. There was a greater relative benefit among patients with more severe disease. Prone positioning confers an additive benefit in oxygenation among patients treated with inhaled nitric oxide.

Obesity (Silver Spring) ; 29(5): 870-878, 2021 05.
Article in English | MEDLINE | ID: covidwho-1059411


OBJECTIVE: Recent cohort studies have identified obesity as a risk factor for poor outcomes in coronavirus disease 2019 (COVID-19). To further explore the relationship between obesity and critical illness in COVID-19, the association of BMI with baseline demographic and intensive care unit (ICU) parameters, laboratory values, and outcomes in a critically ill patient cohort was examined. METHODS: In this retrospective study, the first 277 consecutive patients admitted to Massachusetts General Hospital ICUs with laboratory-confirmed COVID-19 were examined. BMI class, initial ICU laboratory values, physiologic characteristics including gas exchange and ventilatory mechanics, and ICU interventions as clinically available were measured. Mortality, length of ICU admission, and duration of mechanical ventilation were also measured. RESULTS: There was no difference found in respiratory system compliance or oxygenation between patients with and without obesity. Patients without obesity had higher initial ferritin and D-dimer levels than patients with obesity. Standard acute respiratory distress syndrome management, including prone ventilation, was equally distributed between BMI groups. There was no difference found in outcomes between BMI groups, including 30- and 60-day mortality and duration of mechanical ventilation. CONCLUSIONS: In this cohort of critically ill patients with COVID-19, obesity was not associated with meaningful differences in respiratory physiology, inflammatory profile, or clinical outcomes.

Body Mass Index , COVID-19/complications , Obesity/complications , Aged , COVID-19/epidemiology , Critical Illness , Female , Hospitalization , Humans , Intensive Care Units , Male , Massachusetts , Middle Aged , Respiration, Artificial , Retrospective Studies , Risk Factors
Am J Respir Crit Care Med ; 201(12): 1560-1564, 2020 06 15.
Article in English | MEDLINE | ID: covidwho-155108