The numbers of critically ill patients and their average duration of stay in emergency departments (ED) are constantly increasing. ED-validated models to quantify nursing and medical staff resources used across the spectrum of ED care are needed so that staffing resources can be planned and optimally allocated to match service demands.  
by Dr G O’Connor

The initial resuscitation and subsequent care of critically ill and injured patients is a core component of emergency medicine practice [1]. Patients requiring critical care in the emergency department (ED) account for a small proportion of total new patient attendances, but place high demands on ED resources. Research in the United  States has shown that the numbers of critically ill patients and their duration of stay in the ED are increasing [2]. Reasons quoted include lack of available and staffed intensive care beds, ED overcrowding, an ageing population and a higher prevalence of patients with severe chronic medical conditions [3,4,5]. Due to this continuing trend, there is a need to determine the resource demands associated with ED care of critically ill patients.

TISS-28
The Therapeutic Intervention Scoring System (TISS-28) [Figure 1] is a method for quantifying critical care activities performed in the intensive care unit (ICU). This validated scoring system is used to quantify nursing input to patient care, and thus allows staffing levels to be matched appropriately [6]. It scores care interventions and relates this to the duration of nursing care required, so that per 8-hour shift, a typical ICU nurse is capable of delivering nursing activities equal to 46 TISS-28 points. Therefore, one TISS-28 point equates to 10.4 minutes of each 8-hour nurses’ shift.

Use of TISS-28
In St James’ Hospital, Dublin, Ireland, ED-based critical care is delivered in a collaborative and integrated manner by emergency medicine and intensive care unit doctors with nursing support provided by ED nurses. We applied the TISS-28 scoring system to patients who were directly referred to the ICU team by ED staff, as a measure of resource utilisation [7]. Using this ICU standard, 40% of an 8-hour nurses’ shift could be spent on a single critically ill patient. When TISS-28 scores are converted into time, our study showed that, on average, a critically ill patient in the ED required almost 200 minutes of nursing care.

Discussion
Critical care is defined as the assessment and treatment of unstable or potentially unstable cardiovascular, respiratory, metabolic and neurological processes [4] and critical care patients require constant and minute-to-minute titration of therapy according to the evolution of the disease process [8]. Although the patient stay in the emergency department is brief compared to the total length of hospitalisation, physiological determinants of outcome may be established before ICU admission [3,5]. Nguyen et al found a significant reversal of physiological derangement during ED interventions in critically ill patients [3]. It is therefore crucial that optimal standards of critical care are provided in the ED and that appropriate resources are available to facilitate this. Although TISS-28 has not been validated for ED use, our study findings suggest nonetheless that critical care patients require significant ED nursing input [6]. Therefore, even relatively small numbers of critical care patients can have a significant impact on ED nursing resources. To the authors’ best knowledge, there are no similar validated tools to specifically measure nursing or medical resource inputs for high-acuity patients in the ED.

The Jones Dependency Tool has been validated to measure patient dependency in UK Emergency Departments [9], but has not been directly related to the duration of nursing-care required per patient. Other measures of patient dependency include the ED patient matrix and the Conner’s Tool developed in Australia [9]. Research into resource utilisation is facilitated by the implementation of ED case-mix measures, improved information systems and electronic records to allow accurate time measures and ease of access to patient data.

Awareness of the likely nursing time requirement for each ICU patient in the ED should enable nurse managers to plan and adjust nursing care provision in the resuscitation area, according to critical care workload. To this end, applying the ICU standard of TISS-28 may be a useful surrogate marker for resource demands in the ED. However, ED-based tools need to be developed and validated to enable service planning and needs-based resource allocation for the care of critically ill and injured patients in the ED setting.

References
1. Hockberger RS, Binder LS, Graber MA et al. The model of the clinical practice of emergency medicine. Ann Emerg Med 2001; 37: 745-70.
2. Lambe S, Washington DL, Fink A, Herbst K, Liu H, Fosse JS, Asch SM. Trends in the use and capacity of California’s emergency departments, 1990-1999. Ann Emerg Med 2002; 39: 389-396.
3. Nguyen HB, Rivers EP, Havstad S, Knoblich B, Ressler JA, Muzzin Am, Tomlanovich MC. Critical Care in the Emergency Department. A Physiologic Assessment and Outcome Evaluation. Acad Emerg Med 2000; 7(12): 1354-61.
4. Church A. Critical care and emergency medicine. Crit Care Clin 2003 Apr; 19(2): 271-8, viii-ix.
5. Rivers EP, Nguyen HB, Huang DT, Donnino MW. Critical care and emergency medicine. Curr Opin Crit Care 2002; 8(6): 600-6.
6. Miranda DR, de Rijk A, Schaufeli W. Simplified Therapeutic Intervention Scoring System: the TISS-28 items — results from a multicenter study. Crit Care Med 1996; 24(1): 64-73.
7. O’Connor G, Geary U, Moriarty J. Critical Care in the emergency department. Eur J Emerg Med 2009; 16: 296-300.
8. Cowan RM & Trzeciak S. Clinical review: Emergency department overcrowding and the potential impact on the critically ill. Critical Care 2005; 9:291-295.
9. Crouch R, Williams S. Patient dependency in the emergency department (ED): reliability and validity of the Jones Dependency Tool (JDT). Accid Emerg Nurs 2006 Oct;14(4):219-29.
The author
Gabrielle O’Connor,
Emergency Department,
St. James’ Hospital,
Dublin 8,
Ireland.
e-mail : gabbyoco@yahoo.com