Identification and validation of objective triggers for initiation of resuscitation management of acutely ill non-trauma patients: the INITIATE IRON MAN study

Trauma patients are regularly admitted directly to the resuscitation room of an emergency department (ED) at dedicated trauma centers. The relevant alert criteria (e.g., trauma mechanism and pattern, Glasgow Coma Scale [GCS] score < 9 points, systolic blood pressure [SBP] < 90 mmHg, need for intubation) are clearly specified by national guidelines [1]. However, there are no comparable triggers for initiating resuscitation room management of critically ill nontrauma (CINT) patients, posing a challenge for their identification by emergency medical services (EMS) or triage nurses.

Early studies on nontrauma resuscitation room management have found that CINT patients account for about 1.5–2.0% of all patient contacts in German EDs [2, 3] and that the nontrauma vs. trauma ratio of resuscitation room patients may be as high as 4:1 in Germany and Belgium [4]. Although the 30-day mortality of CINT patients is around twice that of trauma patients [2], a recent survey showed that only ~ 50% of the participating German EDs use alert criteria to initiate interdisciplinary resuscitation room management of CINT patients, which are mostly limited to classic acute medical conditions triaged according to the Airway, Breathing, Circulation, Disability, and Exposure (ABCDE) scheme [5]. After establishing a structured resuscitation room protocol based on the ABCDE algorithm (Interdisciplinary Resuscitation Room Management of Acutely Ill Nontraumatic Patients [IRON MAN] protocol; Additional file 1: Fig. S1), we recognized that, aside from prehospital intubation [6], there are no objective triggers available in the literature. The aim of this study was therefore to specify and validate objective trigger factor cut-offs for initiating structured resuscitation management in non-intubated CINT patients. A total of 4 different datasets were used: a prospective derivation cohort, a retrospective validation cohort, and two external validation cohorts (Fig. 1).

In the present INITIATE IRON MAN study, we aimed to identify objective trigger factors for the identification of non-intubated ED patients in need of a structured resuscitation protocol for the first time. Using several complementary patient cohorts, we demonstrated that a relatively simple and pragmatic “any-of-the-following” rule can identify a large proportion of such CINT patients in the ED with high sensitivity and specificity. Specifically, this rule includes as variables out-of-hospital vasopressor use, SBP < 90 mmHg, SpO₂ < 90%, and GCS score < 15 points. In keeping with the MARVEL-inspired title of the study, the mnemonic for the initiation of the IRON MAN protocol in our ED is therefore “ViSiON rule” (Out-of hospital Vasopressor administration, Systolic Blood Pressure, Oxygen Saturation, Non-normal Consciousness). This rule does not intend to replace diagnosis-based alarm criteria but should be used as an adjunctive vital parameter-based basic default for emergency medical services (EMS) and triage nurses. The added value of this rule is that the initiation of any structured resuscitation protocol is based on specific and entirely objective thresholds—and not on subjective judgment or even gut feeling. However, additional studies are needed to determine whether the ViSiON rule improves patient safety, clinical outcome, and resource utilization in the ED.

In the absence of a true gold standard for the identification of CINT patients in the ED, we compared the performance of ViSiON rule with that of two established severity scoring systems. However, the NEWS was developed to identify patients at risk of early deterioration or death, while the qSOFA provides simple bedside criteria to identify adult non-ICU patients with suspected infection who are likely to have poor outcomes. Thus, a direct comparison between NEWS, qSOFA, and the ViSiON rule was not entirely appropriate, although it did yield the following insights. Firstly, we found that many CINT patients in our EDs apparently have only one main A/B, C, or D problem that cannot be detected with a simple cumulative scoring system such as the qSOFA, despite its more liberal threshold values. Lowering the qSOFA cutoff from ≥ 2 to ≥ 1 is an easy solution to this problem, but this would inevitably increase over-triage (as demonstrated by a decrease in the PPV from 100 to 59.6% in the internal validation cohort; data not shown). Secondly, we were seeking specific variable and cut-off values that are very simple to calculate and readily applicable by EMS and triage personnel. The NEWS in particular is highly discriminatory because of its seven multilevel items; however, as the complex calculation is usually performed manually or with a software application, immediate implementation is not always possible, especially in the case of advance telephone-based notifications by EMS. Additionally, the NEWS provides a cumulative assessment of disease severity rather than detecting individual ABCD problems. Both over-triage and complexity must be minimized in a nontrauma resuscitation room management strategy for CINT patients that is feasible and acceptable. For these reasons, the pragmatic and simple ViSiON rule has potential for successful implementation in the ED.

It should be noted that the derivation of the various trigger factor iterations was carried out in patients from a single university hospital ED and could therefore be biased by local practices and subjective perceptions of the study team. We cannot exclude the possibility that the ViSiON rule may operate differently in EDs at other levels of care, with different sensitivities and specificities. In this context, we must acknowledge that the validation of the IRON MAN iterations in dedicated resuscitation room datasets is not entirely consistent, as they do not represent a true gold standard due to subjective patient allocation. Nevertheless, the detection rate of iteration 3 in the external cohorts (83.2% and 80.2%) was quite comparable to its performance in the derivation cohort (85.2%). This is astonishing, as the vital signs in the studies were only recorded on admission to the resuscitation room, i.e. after they had partially improved or even normalized as a result of the measures taken by the EMS. A/B problems in particular can be masked by out-of-hospital administration of oxygen, making the retrospective score estimation somewhat inaccurate at this point.

Although intubated patients were a priori excluded in the current analysis, the OBSERvE and OBSERvE-DUS study subsets likely represent a negative selection of dedicated shock room patients with very unfavorable prognosis [2, 6]. However, the significantly lower mortality in ViSiON-negative patients shows that a clinically relevant differentiation of CINT patients is still possible in this group. It is tempting to speculate that many of the ViSiON-negative patients were allocated to the resuscitation room based solely on the suspected diagnosis (e.g. stroke, myocardial infarction) and were thus not true CINT patients. This hypothesis is further corroborated by the strikingly decreased need for advanced resuscitation measures in these patients. On the other hand, over-triage by the ViSiON rule in the internal validation cohort was very low (13 false alarms in 993 patients). We are therefore confident, that the ViSiON rule could be a pragmatic and effective tool for patient allocation in the ED.

The clear medical need for early recognition and structured care of CINT patients in the ED has emerged in recent years. Objective trigger factors for the initiation of structured resuscitation protocols must be defined to avoid under-triage. Although prospective, multicenter studies are needed for further validation, our findings indicate that the ViSiON rule can facilitate pragmatic identification of ED patients in need of a structured resuscitation protocol based on objective parameters.