key: cord-0763125-oj2445df
authors: Rosa, Gino La; de Aretxabala, Xabier; Martin, Terry; Barreto, Julio; Aguilera, Victor; Wanner, Max; Gonzalez, Pablo; Suarez, Gonzalo; Leiva, Viviana; Herve, Miguel
title: SARS COV-2 Pandemic. Chilean Air Force experience in the air transport of critical ill patients. The first 100 cases
date: 2022-01-10
journal: Air Med J
DOI: 10.1016/j.amj.2021.12.007
sha: d9b729391eafa5619204e79833470c524578b034
doc_id: 763125
cord_uid: oj2445df

Purpose Critical Care air transport has played an important role during the COVID-19 Pandemic. The goal of this manuscript is to analyze results and lessons learned from the evacuation of the first 100 COVID-19 patients transported between medical facilities in Chile. Materials and Methods We reviewed prospective data of patients who were referred for air transport between March 27th and July 09th, 2020. Results Of 115 referred patients, 100 were transported by air. All patients were intubated and mechanically ventilated. Hypertension, diabetes and obesity were the most commonly observed co-morbidities. Our service did not experience any major problems in patient care en route and, among the crew members. We did not observe any SARS COV-2 infections amongst our flight team members during the study period. Twelve (12%) patients died at their destination intensive care unit (ICU), while the remaining 88 patients (88%) returned to their primary hospitals after recovery. Conclusions Air transport of mechanically ventilated patients with COVID-19 infection has been shown to be a safe way of transport, with no in-flight deaths and an in-hospital mortality of 12% which compares favorably with the in-hospital mortality of similar patients who did not undergo air transport.

On March 18, 2020, Chile declared a national catastrophe due to the SARS COV-2 pandemic. At that time, there was a total of 191,122 infected people worldwide of which 265 were reported in Chile 1 . One of the strategies defined by the Chilean government to fight the pandemic was to maintain the availability of critical care beds across the whole territory of Chile. The distance between the northernmost and southernmost cities is 5,040 kilometers, making the evacuation of some patients extremely complex in those places that did not have enough bed capacity. To remedy this problem, the Chilean government tasked the Chilean Air Force to undertake the evacuation of patients from places with low numbers or zero ICU beds to areas with ICU bed availability. One of the main concerns regarding the performance of this plan was the unknown physiological, physical and psychological effects that air medical evacuation might have on the outcome of these patients. Even without the complexities of the highly transmissible disease and the need for patient isolation, it is already well established that the transport of critical ill or injured patients being mechanically ventilated can lead to a higher risk of complications [2] [3] [4] [5] In this paper, we report our results and conclusions from the air transport of ventilated COVID-19 patients.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Nurse (flight nurse), and two nurse assistants. This team is responsible of the care of two patients.

The null hypothesis of this study was that final outcome of patients undergoing air transport was not different from those who did not undergo air transport.

Individual patient isolation chambers were employed for each evacuation. The Before boarding and immediately after landing, the following hemodynamic data, ventilator parameters, temperature and sedation information were recorded:

(1) Hemodynamics: mean, systolic and diastolic blood pressure, heart rate and rhythm, and vasoactive medication strength and dosage details.

(2) Ventilation: ventilator mode, respiratory rate, inspired fraction of oxygen, PEEP, and tidal volume, saturation (SpO 2 ).

(3) Sedation: sedation agitation scale, type and doses of sedative drugs and neuromuscular blocking agents.

Statistics were determined with median and interquartile for continuous variables and number and percentages for categorical variables.

The 30-day mortality was established as the main parameter to be evaluated and data were obtained from the Chilean National Public Register Office.

A total of 115 patients were presented to the Chilean Air Force Critical Care Air Transport Team for transport to areas with availability of ICU beds. Of those, 9

patients did not meet the criteria for evacuation during the first assessment performed by the air medical evaluation team at their respective hospitals, and a further 6 patients were rejected just before boarding at the aircraft parking areas.

Half of the patients were rejected for clinical reasons: hemodynamic instability (two), and unexpected critical respiratory failure (one). The other three patients were unable to be transported due to problems in the negative pressure isolation chamber.

Of the patients proposed for evacuation, 32 (28%) were female and 83 (72%)

were male, with ages ranging between 26 and 83 years (average 67 years).

Before undertaking the evacuation, 74 patients (64.3%) were in already in an ICU, 36 (31.4%) were in an emergency department bed, and five (4.3%) were in an operating room that was being used to manage ventilated patients. All The sedation-agitation scale (SAS) 11 was employed to evaluate the level of sedation. All patients boarded the plane and arrived with SAS levels between I to II. Drugs employed for sedation and neuromuscular blocking are shown in Table 3 . The mean blood pressure, heart rate, temperature and SpO 2 data before boarding and during the flight, are shown in Table 4 .

There were no deaths, no significant medical incidents and no critical events during any of the medevac flights. Post-flight follow-up data revealed the 7, 15, and 30 day mortality as shown in Table 5 .

The With regards to the safety of the flight crew, no SARS COV-2 infections were reported during the study period.

The Chilean Air Force, as part of the crisis response to the COVID-19

pandemic, provided air transport for patients all over the Chilean Territory. The distance between the two extreme cities is over 5,000 km (2,600 nautical miles)

and Santiago (the capital city) is mid-way between the two. The indication for evacuation was the lack of critical care beds in Santiago, and not the necessity for a better management. During the first wave of the pandemic, because of the geography of Chile, different areas of the country had significantly different incidence figures. This allowed the transport of patients from places with high incidence to cities where there were vacant critical care beds. This transport model was also developed by private air ambulance carriers who mainly employed aircraft with capacity for only one patient.

The Chilean Air Force did not have the task of returning the patients after their full recovery to their primary hospitals. The above process was in charge of the Ministry of Health.

In the analysis of the study population, although it may be considered that a selection bias existed, the selection of patients using standard and specific criteria before flight was important. A member of the air evacuation team had the role of visiting and evaluating patients at their referring hospitals. This important step enabled the team to identify those patients who were considered 'not fit' for air medical transport. The decision, based on specialist aeromedical knowledge supported the evaluation performed by the referring critical care physicians who often lack the information and background to be able to risk assess and accurately evaluate those patients who have a significant probability of developing instability during the flight.

A systematic review and meta-analysis of ICU outcomes in patients with COVID-19 shows that patients undergoing invasive mechanical ventilation and infusion of vasoactive drugs had an ICU mortality rate of approximately 40%.

This compares favorably with the post-flight mortality observed in our transported patients during their subsequent ICU admission. 12, 13 As suggested earlier, the main limitation of this analysis is the selection bias of the patients who underwent air transport. The above may lead to a type II error, when we fail to reject the null hypothesis. However, another limitation was the paucity of observations and/or incomplete parameters recorded in some patients during their flight. The lack of a complete record of observation was linked to intra-crew variations in clinical performance that complicated the necessity to replace crewmembers in some of the missions.

One of the concerns before starting the transport, was the possible adverse effects of the duration of the flights on the outcome of patients. In effect, we conclude that patients who underwent the longest evacuation flights, from or to the extreme ends of Chile, did not have a worse outcome when compared with those who had a shorter flight. This is a highly significant finding that adds to published current knowledge about the air transport of Covid-19 infected patients.

The requirement to use an isolation chamber created a limitation in the patient selection process. A proportion of our patients had a significant degree of obesity that precluded their carriage in the chamber, thus making them not unsuitable for transport. This was one of the main problems faced at the time of the evaluation and selection. Due to the standards of best practice published at the time 14 and, clearly, for safety concerns, we did not attempt to transport patients that could not be properly isolated in the chamber. On the other hand, the use of the chambers and the existence of restricted areas inside the aircraft did limit the number of patients that we were able to evacuate on each flight.

There is evidence that supports the benefits of the prone position during the management of patients with respiratory failure due to However, it was impossible to manage prone patients in the isolation chambers employed by our team, and we are therefore unable to support these findings. In retrospect, we consider that our evacuation capability would have been enhanced by the employment of a specially designed isolation chamber with the ability to safely manage prone ventilated patients.

The only clinical events observed during flight were neuromechanical coupling problems observed mainly during the take-off and landing stages of flight.

These are triggered by the sudden movement of patients resulting in G-induced biodynamic forces on existing fragile and/or unstable hemodynamics.

In conclusion, from our experience, and based on the above results, we have validated our evacuation protocol, which allows us to transport patients all over the country without affecting the patient mortality nor affecting the safety of the flight medical crew. These results reassure us that it is feasible to continue with this air transport protocol during the second wave of the pandemic that we are now facing, and during any future incidents requiring urgent transport of ventilated contagious patients by air.

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The authors received no financial support for the research, authorship, and/or publication of this article. 

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