Background
Methacholine challenge tests (MCTs) are used to diagnose airway hyperresponsiveness (AHR) in patients with suspected asthma where previous diagnostic testing has been inconclusive. The test is time consuming and usually requires referral to specialized centers. Simple methods to predict AHR could help determine which patients should be referred to MCTs, thus avoiding unnecessary testing. Here we investigated the potential use of baseline spirometry variables as surrogate markers for AHR in adults with suspected asthma.
Methods
Baseline spirometry and MCTs performed between 2013 and 2019 in a large tertiary center were retrospectively evaluated. Receiver-operating characteristic curves for the maximal expiratory flow-volume curve indices (angle β, FEV1, FVC, FEV1/FVC, FEF50%, FEF25–75%) were constructed to assess their overall accuracy in predicting AHR and optimal cutoff values were identified.
Results
A total of 2983 tests were analyzed in adults aged 18–40 years. In total, 14% of all MCTs were positive (PC20 ≤ 16 mg/ml). All baseline spirometry parameters were significantly lower in the positive group (p < 0.001). FEF50% showed the best overall accuracy (AUC = 0.688) and proved to be useful as a negative predictor when applying FEF50% ≥ 110% as a cutoff level.
Conclusions
This study highlights the role of FEF50% in predicting AHR in patients with suspected asthma. A value of ≥ 110% for baseline FEF50% could be used to exclude AHR and would lead to a substantial decrease in MCT referrals.
Background: Most of severe COVID-19 patients who survive the intensive care remain mechanically ventilated and require weaning and further rehabilitation. Objectives: This study compares the characteristics and outcomes of severe mechanically ventilated COVID-19 patients admitted to a weaning facility. In addition, the study describes patterns of weaning experienced during the three waves of COVID-19 in Israel. Methods: Clinical, demographic and outcome data was gathered retrospectively for 70 severe mechanically ventilated patients. Univariate analysis was performed to explain the variability in outcome variables. Results: Weaning success was 94% with mean weaning duration of 13±17 days. None of the demographic and clinical variables examined influenced the weaning duration, however patients with morbid obesity and/or diabetes were found to have shorter total duration on mechanical ventilation, hereby suggesting the presence of an obesity paradox. Extra corporal membrane oxygenation (ECMO) was used in 29% of the patients, and didn't influence the weaning duration in spite being associated with higher rate of pleural complication. There were three main weaning patterns seen in different overlapping levels in the cohort patients: low capacity extra pulmonary pattern, fibrotic-bullosic pulmonary injury pattern and nonspecific interstitial pneumonitis pattern. Conclusions: The current study shows a high success rate of weaning, independent on comorbidities and previous ECMO use.
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