key: cord-0720654-mnq6yqq5
authors: Huq, F.; Manners, E.; O'Callaghan, D.; Thakuria, L.; Weaver, C.; Waheed, U.; Stümpfle, R.; Brett, S. J.; Patel, P.; Soni, S.
title: Patient outcomes following transfer between intensive care units during the COVID‐19 pandemic
date: 2022-02-28
journal: Anaesthesia
DOI: 10.1111/anae.15680
sha: b40571551f4e1e6c7e63d627dec16e5ea12b9763
doc_id: 720654
cord_uid: mnq6yqq5

Transferring critically ill patients between intensive care units (ICU) is often required in the UK, particularly during the COVID‐19 pandemic. However, there is a paucity of data examining clinical outcomes following transfer of patients with COVID‐19 and whether this strategy affects their acute physiology or outcome. We investigated all transfers of critically ill patients with COVID‐19 between three different hospital ICUs, between March 2020 and March 2021. We focused on inter‐hospital ICU transfers (those patients transferred between ICUs from different hospitals) and compared this cohort with intra‐hospital ICU transfers (patients moved between different ICUs within the same hospital). A total of 507 transfers were assessed, of which 137 met the inclusion criteria. Forty‐five patients underwent inter‐hospital transfers compared with 92 intra‐hospital transfers. There was no significant change in median compliance 6 h pre‐transfer, immediately post‐transfer and 24 h post‐transfer in patients who underwent either intra‐hospital or inter‐hospital transfers. For inter‐hospital transfers, there was an initial drop in median PaO(2)/F(I)O(2) ratio: from median (IQR [range]) 25.1 (17.8–33.7 [12.1–78.0]) kPa 6 h pre‐transfer to 19.5 (14.6–28.9 [9.8–52.0]) kPa immediately post‐transfer (p < 0.05). However, this had resolved at 24 h post‐transfer: 25.4 (16.2–32.9 [9.4–51.9]) kPa. For intra‐hospital transfers, there was no significant change in PaO(2)/F(I)O(2) ratio. We also found no meaningful difference in pH; PaCO(2);(,) base excess; bicarbonate; or norepinephrine requirements. Our data demonstrate that patients with COVID‐19 undergoing mechanical ventilation of the lungs may have short‐term physiological deterioration when transferred between nearby hospitals but this resolves within 24 h. This finding is relevant to the UK critical care strategy in the face of unprecedented demand during the COVID‐19 pandemic.

Inter-hospital transfer of critically ill patients is often required within the National Health Service (NHS) in the UK, with over 11,000 critically ill patient transfers per year [1] . This may occur for several reasons including transfer to a specialist centre for specific clinical management, repatriation and capacity reasons. Before 2017, the latter accounted for only a small proportion (4.4%) of transfers overall in the South West England Critical Care Network [2] .

COVID-19, caused by SARS-CoV-2 infection, has caused a high incidence of acute respiratory and multi-398 organ failure requiring organ support and admission to an intensive care unit (ICU) [3, 4] . In the UK, there have been several surges of patients with COVID-19 resulting in high numbers of hospital and, subsequently, ICU admissions [5] , creating pressure on bed capacity. During these periods, a high number of inter-hospital ICU to ICU transfers took place to relieve pressure on beds, preventing units becoming overwhelmed, and to create capacity for admissions from the Emergency Department. Indeed, nationally, 2793 patients were transferred between ICUs between September 2020 and March 2021, of which 2320 were for comparable clinical care, rather than for specialist management, and, in London, 20% of ICU admissions were due to transfers from other hospitals [6] .

The North West London Critical Care Network is a collaboration of five NHS Trusts (10 hospital sites), covering 1.8 million patients [7] . In order to manage the increased ICU demand during the first peak of the COVID-19 pandemic in 2020, a high number of ICU transfers occurred within this network [8] . However, there is a paucity of data examining clinical outcomes following transfer of patients and whether this strategy affects patients' physiology or outcome. This is a particularly pertinent issue since transfers of critically ill patients can be associated with complications or difficulties in up to two-thirds of cases [9] .

Understandably, therefore, careful patient selection is advised to mitigate these risks [10] .

We investigated all critically ill COVID-19 patient transfers between three different hospital sites over a 1-y period (March 2020 to March 2021). We evaluated whether any physiological deterioration occurred following an ICU transfer and the success of ICU transfers as a strategy to compensate for increased ICU demand.

Ethical approval was not required as this study was carried out as a service evaluation within the NHS and recorded 

During the study period, there were a total of 504 critically ill patients transferred within Imperial College Healthcare NHS Trust, of which 137 met our inclusion criteria ( Table 1 ). The overall study cohort had a mean (SD) age of 62 (11) Forty-five patients underwent inter-hospital transfer compared with 92 who were moved between ICUs within the same hospital. Table 1 summarises the baseline characteristics of inter-and intra-hospital ICU transfers and key differences between these groups. There was no increase in mortality in inter-hospital transfers compared with intra-hospital transfers.

Inter-hospital transfers involved a transfer team, connection to a portable ventilator, an ambulance journey to a new hospital site and ICU, and then synchronisation to another ventilator following arrival. Intra-hospital transfers were less cumbersome, shorter and did not involve an ambulance journey. Therefore, as expected, patients chosen for inter-hospital transfer were suitably selected, with less deranged physiological parameters (e.g. P/F ratios) compared with those who underwent intra-hospital transfers (Tables 1 and 2 ). . 3b) . Due to these results, we closely assessed which groups of patients, based on the severity of ARDS, were most at risk of deterioration in P/F ratio. As demonstrated in Fig. 3c-f , a deterioration in P/F ratio was most pronounced in those whose ARDS had resolved (baseline P/F ratio > 39.9 kPa), but this recovered within 24 h post- transfer. We also found no meaningful difference in pH, PaCO 2, base excess, bicarbonate or norepinephrine requirements between either inter-or intra-hospital ICU transfers ( Table 2 ).

We were reassured to find that, although there was some short-term decline, none of the parameters investigated in this study demonstrated significant deterioration from a 402 putting significant pressure on ICU beds [12] . Data from the first wave of infections in the UK show that daily admissions to ICU trebled during the first peak around March-April 2020 [13] , with a large London ICU performing tracheal intubation on 7.5 COVID-19 patients every day [8] . Patients with COVID-19 ARDS often require prolonged pulmonary mechanical ventilation [14] , dramatically increasing the need for critical care beds. Indeed, during the second wave in the UK, the three hospitals in this study facilitated a surge capacity of around 150% in ICU beds [15] . Particularly instrumental in allowing for surge capacity of ventilated [16] . A case series of six COVID-19 patients with severe ARDS whose lungs were mechanically ventilated and were evacuated via amphibious assault ship, reported no significant change in P/F ratio posttransfer [17] . Data from the USA also confirmed that interhospital evacuation of COVID-19 patients whose lungs were mechanically ventilated did not increase mortality [18] .

Previous data in transfer of non-COVID ARDS patients are, similarly, sparse. In 2002, a study of 66 patients reported a significant improvement in P/F ratio over the course of an hour-long transfer (8.5 AE 2.7 kPa pre-transfer and 9.7 AE 3.6 kPa post-transfer) [19] and this is comparable with studies which have investigated the effect of transfers in critically ill ICU patients and shown no increase in mortality [20, 21] . Several studies also exist which demonstrate an increase in mortality following inter-hospital transfer of ICU patients [22, 23] , which highlights the severe risks associated with non-clinical transfer of patients between institutions. were not included as they may have had deranged physiology as a result of their procedure rather than the transfer.

In conclusion, patients with COVID-19 undergoing mechanical pulmonary ventilation do not undergo lasting physiological deterioration when transferred between nearby hospitals. This finding is a significant success for national critical care strategy in the face of unprecedented demand during the ongoing COVID-19 pandemic.

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