key: cord-0937904-lbo4rm88
authors: Jouffroy, Romain; Lemoine, Sabine; Derkenne, Clément; Kedzierewicz, Romain; Scannavino, Marine; Bertho, Kilian; Frattini, Benoit; Lemoine, Frédéric; Jost, Daniel; Prunet, Bertrand
title: Prehospital management of acute respiratory distress in suspected COVID-19 patients
date: 2020-09-14
journal: Am J Emerg Med
DOI: 10.1016/j.ajem.2020.09.022
sha: 2b223865a903e1a3e08392393535a313c51a68b6
doc_id: 937904
cord_uid: lbo4rm88

BACKGROUND: In December 2019, coronavirus disease (COVID-19) emerged in China and became a world-wide pandemic in March 2020. Emergency services and intensive care units (ICUs) were faced with a novel disease with unknown clinical characteristics and presentations. Acute respiratory distress (ARD) was often the chief complaint for an EMS call. This retrospective study evaluated prehospital ARD management and identified factors associated with the need of prehospital mechanical ventilation (PMV) for suspected COVID-19 patients. METHODS: We included 256 consecutive patients with suspected COVID-19-related ARD that received prehospital care from a Paris Fire Brigade BLS or ALS team, from March 08 to April 18, 2020. We performed multivariate regression to identify factors predisposing to PMV. RESULTS: Of 256 patients (mean age 60 ± 18 years; 82 (32%) males), 77 (30%) had previous hypertension, 31 (12%) were obese, and 49 (19%) had diabetes mellitus. Nineteen patients (7%) required PMV. Logistic regression observed that a low initial pulse oximetry was associated with prehospital PMV (ORa = 0.86, 95%CI: 0.73–0.92; p = 0.004). CONCLUSIONS: This study showed that pulse oximetry might be a valuable marker for rapidly determining suspected COVID-19-patients requiring prehospital mechanical ventilation. Nevertheless, the impact of prehospital mechanical ventilation on COVID-19 patients outcome require further investigations.

Coronavirus disease (COVID-19) is currently spreading freely worldwide, after the first cases described in Asia in late 2019 (1) (2) (3) (4) . On March 11 th , 2020, the World Health Organization (WHO) declared COVID-19 a pandemic (5) . Despite worldwide COVID-19 affected over 2 million patients, the overall mortality rate remains low around 765 000 deaths (6-9), at this time of writing. COVID-19 is caused by an infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), and it presents in various clinical manifestations (10). Although most infections are not serious, 25% of cases are life-threatening (6) . Among these, the respiratory form is the most severe, because it presents as acute respiratory distress (ARD) without clinical signs. Typically, to respiratory presentations of COVID-19 may be various and it often present different degrees of hypoxia and hypoxemia, which require inhospital admissions to the emergency department (ED), a special ward, or an intensive care unit (ICU).

In the prehospital setting, we previously reported that dyspnea was the main symptom required for dispatching the Paris Fire Brigade prehospital emergency service (11). Due to the pandemic status of COVID-19, there is a gap between patient needs (i.e., severe COVID-19 ARD, which requires support ventilation) and medical resources (medical ventilator devices).

This retrospective observational study included all patients over 18 years old that required intervention by a Paris Fire Brigade team (BLS and/or ALS) between March 08 and April 18, 2020, due to ARD related to suspected COVID-19 accord to the world health organization (WHO) definition (12). No exclusion criteria were applied. ARD was defined as the presence of a constellation of symptoms suggestive of COVID-19, dyspnea and/or a requirement for oxygen supplementation, based on initial prehospital pulse oximetry. Suspicion of COVID-19 was based on the latest WHO definition (12).

The prehospital Paris Fire Brigade emergency medical system is a 2-tiered response system: the BLS tier is served by 200 teams of 3 to 5 rescuers deployed in 77 stations; the ALS tier is served by 7 ambulance teams comprising an emergency physician, a nurse, and a driver (13) .

The prehospital Paris Fire Brigade ALS team utilizes a prehospital mobile ICU equipped with medical devices and drugs, which enables the initial management of primary organ deficiencies (neurological, respiratory, and cardiovascular) (14) . ALS team physicians can perform echography and blood gas analyses in the prehospital setting. Upon assessing an emergency call, the dispatch center operator might decide to send a BLS team, an ALS team, or both teams at the same time, based on the clinical history and symptoms reported by the patient, the relatives, or a witness. Once rescue teams have arrived at the scene and the remains controversial whether the treatment of choice for ventilation should be non-invasive (simple oxygen supplementation, continuous positive airway pressure, or bilevel positive airway pressure) or invasive (mechanical support with intubation), especially given that the underlying condition can be fatal and COVID-19 is highly contagious (21,22). Except for facial masks for delivering high oxygen concentrations, the low rate of applying non-invasive ventilation (positive airway pressure modes) could be explained by the fear of risking SARS-CoV-2 aerosolization and contamination of healthcare providers (23-26). To date, no data are available on the rate of healthcare provider contamination or on how the low rate of prehospital non-invasive ventilation use might impact patients with suspected COVID-19 ARD. Currently, for patients with suspected COVID-19 ARD, the optimal mode of respiratory support, before PMV is required, is a matter of debate (27). This issue has become a challenge in prehospital pandemic COVID-19 ARD management, due to the inadequate balance between needs and resources. Therefore, it is crucial to identify patients at risk of unfavorable respiratory evolution to ensure adequate prehospital ARD management and transportation to the appropriate facility. We believe that the key is careful patient selection to avoid delaying PMV to patients that require it. Our results suggested that the pulse oximetry, measured before and after oxygenation, might provide a means of identifying patient eligibility for prehospital non-invasive ventilation. Further prospective studies are needed to confirm the usefulness of this potential marker.

Our study had some limitations. First, it was a retrospective study, with the usual inherent limitations. Second, children were not included in the study; thus, our results might not be applicable to a pediatric population, particularly because SARS-CoV-2 does not have equivalent effects in children and adults (28). Third, this study was conducted in a single country and in single city, based on a particular prehospital emergency system with a 2-tiered response. Therefore, it might not be generalizable to all emergency systems. Fourth, we did J o u r n a l P r e -p r o o f Journal Pre-proof not have data on the rate of hospital admissions for patients with SARS-CoV-2 infection that did not receive a prehospital emergency service intervention. Fifth, we could not rule out the potential impact of unknown confounders on our results, e.g. we did not assess the potential effect of the underlying frailty and disease duration prior call to the EMS. Sixth, we cannot report the potential of non-invasive positive pressure ventilator devices, i.e. high flow non-invasive oxygen therapy device, because they are not recommended because of a presumed aerosol generating risk in an ambulance. Last, but not least, this study did not report any association between prehospital care and the outcome; for example, we did not report the rate of in-hospital deaths or the rate of in-hospital MV applications, which could have demonstrated the adequacy of the prehospital intervention.

In conclusion, to the best of our knowledge, this study was the first study to describe a large number of consecutive patients with ARD and suspected COVID-19 that were assessed by a prehospital ALS team. We found that a low initial pulse oximetry value was associated with the need for PMV. Further prospective studies are needed to confirm the usefulness of pulse oximetry in selecting patients that are eligible for prehospital non-invasive ventilation, the greatest challenge in the prehospital management of COVID-19-related ARD. 

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