In this study we highlight the different aspects of the first wave of the SARS-CoV-2 pandemic influencing PICUs in Switzerland. Although initially the disease was thought to affect predominantly adult departments, in the course of the pandemic, pediatric units and PICUs were more and more affected. Our results show that the absolute number of pediatric patients requiring intensive care due to severe SARS-CoV-2 and PIMS-TS during the study period was low. However, PIMS-TS patients requiring intensive care constituted a relatively large proportion (14%) of all hospitalized patients with laboratory confirmed SARS-CoV-2 under the age of 20 years. Similar results of hospitalized children and adolescents admitted to PICUs have been reported in other studies [31, 32].
In our study the PIMS-TS patients presented about 4 to 5 weeks after the peak of the total number of new SARS-CoV-2 cases in the general population (Figure 1) supporting the notion of PIMS-TS being a post-infectious phenomenon. Similar temporal distributions have been shown in other studies [33].
The profile of organ supportive therapies used in our study population was alike to that described in other studies [13, 34]. Regarding the employment of anti-inflammatory medication, Davies et al. described approximately 70% PICU patients with PIMS-TS receiving steroids and 70% receiving intravenous immunoglobulin, which correlates with the here presented data [34]. However, and opposed to the 67% in our cohort, use of biological agents in that study was limited to 20% [34]. This is likely to be explained by the novelty of the disease, the low caseload per each individual Swiss PICU, and the lack of evidence and consensus on optimal treatment protocols. Evidence in the form of randomized controlled trials remains scarce. Although Switzerland is a small country, eight independent PICUs treat critically ill children. Each PICU is quite small, operating a relatively small number of beds. Although cooperation between the PICUs exists in several forms, every day professional exchange is not intensive. However, in the course of the first wave of the pandemic, the PICUs recognized, that it is important to cooperate, to coordinate actions and to exchange experiences with each other to improve the management of these patients. As a consequence, Swiss consensus guidelines for best practice were established by a multidisciplinary group of Swiss pediatric clinicians with expertise in intensive care, immunology, rheumatology, infectious diseases and hematology during the second wave of the pandemic at the end of 2020 (http://transfer.imk.ch/f.php?h=3R2LIfFV&d=1).
Although few in numbers and with a low predicted mortality, PIMS-TS patients required a high resource load per case to manage. Our data shows, that PIMS-TS patients remained longer in PICUs and required positive pressure ventilation for a longer time period than general PICU patients. In addition, their management caused a higher workload as illustrated by the bigger proportion of shifts with a higher SSICM categories as well as higher total NEMS scores. This mirrors the complexity of these cases and the strain they bring to PICUs.
At the beginning of the pandemic a variety of measures to prepare the Swiss hospital network for the pandemic were instituted on federal as well as regional levels. Due to the decentralized governmental system of Switzerland those measures varied markedly between different regions. Similar measures were applied to children´s and adult hospitals in the same region. Scheduled interventions were cancelled to reduce the need for postinterventional intensive care and to increase resources for emergency admissions. In some hospitals skilled PICU staff was recruited to support the adult ICUs forcing PICUs to temporally operate with a reduced number of team members. Those different logistical factors, in addition to the burden of PIMS-TS patients, influenced the workload and the occupancy of the individual PICUs differently, depending on the presence or absence of the single factors and their temporal relationships. Due to their complexity the exact quantification and comparison of the impact of all of these factors was unfortunately not possible. Thanks to the experiences of the first wave, we recognize that the individual PICUs should be organized by a regional and not, federal level and in accordance with but not the same to the surrounding adult hospitals. A contemporary analysis of the burden and duties of the individual PICU is essential to reduce the workload of the PICU and simultaneously to ensure the bed occupancy for economic reasons.
Our work is unique for several reasons. It is a comprehensive analysis of all of the relevant cases in our entire country, a feature other works published to date have not been able to offer. The exhaustive coverage enables us also to put our patient numbers into a bigger context through comparisons with epidemiological data on less severely affected patients as well as our whole population. In addition, we put emphasis on evaluating case severity and workload and conducted a comparative analysis with data on general PICU patients hospitalized in the previous year. Furthermore, we analyzed organizational factors influencing PICUs not strictly related to the affected patients but rather the general situation in the Swiss healthcare system which also took a toll on the PICUs during first wave of the pandemic, an aspect that has received little coverage until now.
Our study has some limitations. The retrospective design restricts the range of data available from the study population, this applies for both the historical comparison cohort as well as the epidemiological PIMS-TS data. Further, the low case number of PIMS-TS patients limits the generalizability of these results to other countries and health-care settings. However, the aim of this study was to analyze the data of Switzerland, the data of a small country with several PICUs, organized in a decentralized manner. In addition, the vast array of logistical factors influencing the PICUs during the pandemic was not quantifiable.
In conclusion, the SARS CoV-2 pandemic does not exclusively affect adult ICUs, with PICUs also having to face a variety of eventualities with a plethora of consequences. PIMS-TS patients are, although few in numbers, demanding to manage, especially in light of the multitude of logistical changes burdening PICU teams during the pandemic. As pandemic continues, reflecting and learning from experience is essential to reduce the workload and optimize the occupancy in each individual PICU.