Prevalence of exercise-induced oxygen desaturation after recovery from SARS-CoV-2 pneumonia and use of lung ultrasound to predict need for pulmonary rehabilitation.

BACKGROUND: Persistence of breathlessness after recovery from SARS-CoV-2 pneumonia is frequent. Recovery from acute respiratory failure (ARF) is usually determined by normalized arterial blood gases (ABGs), but the prevalence of persistent exercise-induced desaturation (EID) and dyspnea is still unknown. METHODS: We investigated the prevalence of EID in 70 patients with normal arterial oxygen at rest after recovery from ARF due to COVID-19 pneumonia. Patients underwent a 6-min walking test (6MWT) before discharge from hospital. We recorded dyspnea score and heart rate during 6MWT. We also investigated the possible role of lung ultrasound (LU) in predicting EID. Patients underwent a LU scan and scores for each explored area were summed to give a total LU score. RESULTS: In 30 patients (43%), oxygen desaturation was >4% during 6MWT. These patients had significantly higher dyspnea and heart rate compared to non-desaturators. LU score >8.5 was significantly able to discriminate patients with EID. CONCLUSION: In SARS-CoV-2 pneumonia, ABGs at discharge cannot predict the persistence of EID, which is frequent. LU may be useful to identify patients at risk who could benefit from a rehabilitation program.

Determination of halogenated phenols in raw and potable water by selected ion gas chromatography-mass spectrometry.

Pentafluorobenzylation and in situ acetylation are compared in the determination of phenol and halogenated phenols in water samples. The latter technique is considered superior to the former for determining phenols at the ng/L level because of less background interference and better recoveries (80% or better except for pentachlorophenol and trichloroguaiacol which had recoveries of about 60%). Further evaluation of the in situ technique by electron capture gas chromatography and gas chromatography-mass spectrometry shows that the latter, in the selected ion monitoring mode, is more suitable because, unlike GC-ECD, it can confirm and quantitate all phenols. In particular, GC-ECD could not detect even high levels of phenol and the monohalogenated phenols. Phenols at 5-473 ng/L were detected in some Canadian drinking water supplies by the in situ acetylation technique combined with GC-MS.