Early mobilization of critically ill patients has many theoretical benefits. It has the promise of reducing muscle weakness, helping to limit the occurrence of delirium, preventing complications such as pressure ulcers and deep-vein thrombosis, and reducing adult ICU and hospital stay (1,2). In pediatric intensive care practice, we seek to implement mobilization early during admission, and for close to 10 years, we have known that this intervention is both feasible and safe (3,4).

In this issue of Pediatric Critical Care Medicine, Choong et al (5) present a two-center study in what they call “a hybrid implementation study” to evaluate both implementation and clinical patient outcomes, that is, a hybrid type 2 design (6). The authors’ bundle of care consisted of three components: 1) pain and sedation management; 2) delirium management; and 3) early mobility activities. The implementation strategies included education of the PICU teams, appointing champions, providing audit and feedback, and organizing daily team “huddles” for better communication. The primary endpoints of the study were implementation outcomes such as bundle compliance, performance in the process of care (e.g., daily goal-setting of early mobilization), and acceptability of the bundle components and the implementation strategies. The secondary endpoints were clinical outcomes, such as pain intensity, delirium prevalence, iatrogenic withdrawal symptoms, length of PICU stay, and duration of ventilation. The authors found that within 6 months, bundle compliance exceeded 90%. Daily goal-setting for mobilizing patients improved in both sites from 2% to 62.8% and 36.1 to 80%, respectively. Nevertheless, the implementation of the bundle did not have a significant positive impact on the clinical outcomes, probably because of small sample sizes (5). However, we speculate the possibility that early mobilization has other potential benefits after the PICU stay, such as shorter rehabilitation and less risk of post intensive care syndrome. We could argue that early mobilization has a greater effect in adults than in children and infants. More information may come from an ongoing large, multicenter stepped-wedge cluster randomized controlled study (7). This randomized study aims to test days alive free of mechanical ventilation as the primary outcome. Secondary outcomes include days alive, delirium- and coma-free days alive, and functional status at the time of PICU discharge. But do we really have to wait for the results of the trial before we move on with the implementation of early mobilization, or can we agree that early mobilization is just good clinical practice? Indeed, the 2022 Society of Critical Care Medicine clinical practice guideline on Prevention and Management of Pain, Agitation, Neuromuscular Blockade, and Delirium in Critically Ill Pediatric Patients With Consideration of the ICU Environment and Early Mobility “suggest(s) performing early mobilization to minimize the effects of immobility…” (Strength of recommendation—conditional; Quality of evidence—low) (8).

Traditionally, critically ill children were kept immobile and deeply sedated to prevent instability and therefore were not mobilized. Studying both the effectiveness and the implementation outcomes of this bundle as done by Choong et al (5) in a hybrid trial design is—we believe—the next step to facilitate the implementation and its evaluation of early mobilization in PICU practice. Indeed, this recent work follows a bundle with other components. For example, the authors have published the results of the “Glass Door,” a communication sheet located in the door-front of each patient room to facilitate team communication and daily goal setting on bundle elements, for example, mobility (9). There are also the results of an international online survey carried out in 2017–2019 by the Prevalence of Acute Rehabilitation for Kids in the PICU investigators, which, although supporting the uptake of early mobilization in routine clinical practice, implementation is hampered by concerns about lack of evidence and knowledge (10).

In this context, the relatively young field of implementation science is increasingly important because it explains how new interventions can be put into practice, as recently described by the Excellence in Pediatric Implementation Science group for the Pediatric Acute Lung Injury and Sepsis Investigators Network (11). In most cases, the success of implementation depends on a range of factors. For example, regarding the early mobilization bundle, barriers and facilitators of implementation can be categorized according to the following domains: the interventions (i.e., early mobilization bundle); the healthcare professionals’ characteristics; inner setting (i.e., team culture, organizational characteristics); outer setting (i.e., patient or client perspectives, external policies and regulations); and the implementation process itself. An implementation framework such as the Consolidated Framework for Implementation Research could help identify relevant determining factors (12). One main advantage of implementation studies is the focus on the effects of the intervention in the real world of clinical practice. In contrast, the traditional randomized controlled study has restrictive inclusion criteria, which may hinder subsequent generalization of the findings to a larger population or setting.

What we also learn from the study by Choong et al (5) is that generating change is usually more challenging than maintaining the status quo, particularly if innovations necessitate complex changes in clinical practice, interdisciplinary collaboration, or reorganization of care. In this context, early mobilization is an example of a complex intervention because it must align with treatment of pain and sedation, and delirium management. Even more complex is the introduction of the so-called ABCDEF bundle because it involves even more components of care (10). A study conducted in adult ICUs has revealed that the complete implementation of the ABCDEF bundle is linked to improved survival rates, as well as reduced durations of mechanical ventilation, delirium, and coma (13). Recently, the results of a multicenter study on the clinical outcomes following the application of the Pediatric ABCDEF bundle were published (14). The study by Choong et al (5) focused on assessing the adherence to bundle utilization in ventilated pediatric patients. While they did note an increased utilization of the bundle, they did not find any associations with mechanical ventilation duration, PICU length of stay, or the presence of delirium, in contrast to findings in adult patients (14,15). Unexpectedly, upon conducting adjusted analyses, enhanced bundle utilization correlated with a decreased probability of death.

In a scoping review conducted in 2023 by Noone et al (16), the objective was to investigate the barriers and facilitators associated with early mobilization programs in PICUs as perceived by nurses, patients, and families. Gaining insight into these factors is crucial for fostering the effective adoption of early mobilization initiatives. Drawing from both quantitative and qualitative studies, the review underscored significant barriers encountered in implementing early mobilization in PICUs. These barriers encompassed increased work demands, insufficient motivation and knowledge, resistance to change, and constraints stemming from limited staffing and resources (16). The scoping review also addressed safety issues: PICU staff are concerned that early mobilization could lead to hemodynamic instability, removal of tubes and lines, and agitation. Also, lack of interdisciplinary collaboration was mentioned as a barrier because early mobilization programs require multidisciplinary collaboration between pediatric intensivists, physical therapists, nurses, and respiratory therapists. Various ways to counter these barriers were identified as well. First, interdisciplinary collaboration is crucial for seamless integration of mobilization activities into the patient’s care plan. Second, appointing champions with enough time to facilitate implementation activities. These barriers and how they may be overcome provides some insight into what strategies, for example, specific approaches to integrate early mobilization into routine care, an individual PICU will need to perform before early mobilization practices becomes an everyday reality.

Choong et al (5) concluded that early patient mobilization was successful in both study PICUs despite differences in service delivery, access to resources, processes of care, and unit culture. Implementation strategies used in the study by Choong et al (5), and other quality improvement studies, are educational materials, local clinical protocols, local champions, goal setting, and use of audit and feedback (3–5,17). At present, there is still insufficient evidence on which strategies are most effective for implementing early mobilization in PICUs. It remains unknown whether strategies are performed as intended and to what extent the strategies are adopted or adhered to. However, executing a process of evaluation helps to understand why some implementation strategies in a particular context bring about change while others fail (11). Hence, we may need another type of hybrid study, beyond the design used in the current report. For example, a so-called “type 3 implementation study” in which the effectiveness of strategies for implementing early mobilization in PICUs are studied at the same time (6). For instance, we assume that champions act as both role model for colleagues and as an exemplary professional they have a positive effect in their adherence to the early mobilization bundle, as shown in the study of Choong et al (5).

In conclusion, we believe that implementation models, frameworks, and alternatives to randomized clinical studies may enable a better understanding of the local PICU factors that are important in our choice of strategies for the early uptake of mobilization in critically ill children. Future research should focus on sustainability, scalability, and economic evaluations for broader adoption of early mobilization programs.

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