BackgroundProne positioning has a beneficial role in COVID-19 patients receiving ventilation but lacks evidence in awake non-ventilated patients, with most studies being retrospective, lacking control populations and information on subjective tolerability.MethodsWe conducted a prospective, single-centre study of prone positioning in awake non-ventilated patients with COVID-19 and non-COVID-19 pneumonia. The primary outcome was change in peripheral oxygenation in prone versus supine position. Secondary outcomes assessed effects on end-tidal CO2, respiratory rate, heart rate, and subjective symptoms. We also recruited healthy volunteers to undergo proning during hypoxic challenge.Results238 hospitalised patients with pneumonia were screened; 55 were eligible with 25 COVID-19 patients and 3 non-COVID-19 patients agreeing to undergo proning – the latter insufficient for further analysis. 10 healthy control volunteers underwent hypoxic challenge. Patients with COVID-19 had a median age of 64 years (interquartile range [IQR] 53–75). Proning led to an increase in SpO2 compared to supine position (difference +1.62%; p=0.003) and occurred within 10 min of proning. There were no effects on end-tidal CO2, respiratory rate, or heart rate. There was an increase in subjective discomfort (p=0.003), with no difference in breathlessness. Among healthy controls undergoing hypoxic challenge, proning did not lead to a change in SpO2 or subjective symptom scores.ConclusionIdentification of suitable patients with COVID-19 requiring oxygen supplementation from general ward environments for awake proning is challenging. Prone positioning leads to a small increase in SpO2 within 10 min of proning though is associated with increased discomfort.
We read with interest the article by Leighton et al. describing the use of recombinant factor VIIa (rFVIIa) in women with amniotic fluid embolism. 1 The authors report this as a systematic review. We are concerned, however, that the methods used have limitations that render the results seriously flawed. The authors identified only five cases from the literature using their search strategy, and identified the remaining cases through hemostasis and rFVIIa registries and data sources. They failed, however, to contact any amniotic fluid embolism registries or databases to identify cases treated with rFVIIa. The authors report that the Amniotic Fluid Embolism Register in the United Kingdom collected data on cases between 1997 and 2004, 2 but failed to note that the United Kingdom Obstetric Surveillance System has been prospectively collecting information on cases through active negative surveillance since 2005. 3 We have previously reported a national, population-based series of 60 women with amniotic fluid embolism, who delivered between February 2005 and January 2009, and note in our report 3 that 15 of these women were managed with rFVIIa. These cases would thus more than have doubled the number of cases included in the review, adding significantly to the power and robustness of the analysis. These additional cases have the advantage of being a national, population-based cohort, identified prospectively through active, negative surveillance and thus free from selection bias, unlike case reports from the literature. In addition, we were not entirely clear why the authors of the review excluded from their comparison cohort women with amniotic fluid embolism who did not receive any surgery to control hemorrhage. This will immediately exclude from the comparison cohort the severest cases of amniotic fluid embolism: women who die very rapidly before there is time for any operative intervention to control hemorrhage. The observed increased risk of death or disability associated with rFVIIa may thus simply reflect this potentially biased selection of the comparison cohort. As we note in our analysis, 3 only one of the 15 women treated with rFVIIa had a surgical intervention to control hemorrhage, further reinforcing our belief that to include only a comparison cohort managed with surgery for hemorrhage is inappropriate. We believe that the only robust way to advance our management of rare conditions such as amniotic fluid embolism is through prospective, population-based data collection and combined analysis of cases confirmed using an agreed case definition. For this reason, we have established the International Network of Obstetric Survey Systems to facilitate such studies. Data on women with amniotic fluid embolism are being collected prospectively in Australia,
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