Decision Making in Emergency Critical Care

SECTION 1 - Introduction

1
Emergency Critical Care

Robert M. Rodriguez

THE GROWTH OF EMERGENCY DEPARTMENT CRITICAL CARE

Emergency physicians are assuming an ever-expanding role in the care of critically ill patients. The emergency department (ED) is the hospital entry point for virtually all trauma admissions, over 70% of adult sepsis admissions, and the vast majority of patients with acute myocardial infarction, acute stroke, and major gastrointestinal bleeding.1

More than a quarter of all patients admitted to the hospital from the ED are critically ill at their time of presentation.2,3 While some of these patients are admitted to the ICU, many more are resuscitated and stabilized in the ED. Because of increases in ED boarding and delays in ICU transfer, however, EDs are being asked to provide extended ICU-level care.4 This new volume of ED-based critical care has not only demanded an increasingly solid foundation in critical care medicine from the emergency physician but also given rise to a new specialist: the emergency intensivist. As experts on the presenting phase of critical illness, these physicians are valued members of the critical care team and are uniquely suited to provide a seamless patient transition from the ED to the ICU.

Physicians with dual training in emergency and critical care medicine have successfully combined careers in the ED and ICU for decades; but only in the past several years has there been a formal EM/critical care certification pathway. Historically, emergency physicians who wanted critical care medicine certification had to complete a second residency in addition to fellowship training (usually through an EM/internal medicine/critical care medicine combination). Years of intense lobbying have finally resulted in a more practical certification pathway for the EP. After completing an EM residency and an approved 2-year critical care medicine fellowship, emergency physicians can now be certified in critical care medicine through the American Board of Internal Medicine. This cohort, which began as a handful of triple-trained EM critical care physicians, now encompasses more than 200 EM physicians certified in critical care medicine in the United States.6

This surge of EM intensivists has been paralleled by exciting innovations in ED-based diagnosis and therapy. Given that patient physiology changes most rapidly during the first few hours of patient presentation, it is not surprising that these new approaches are profoundly affecting morbidity and mortality in the critically ill.3 ED-based landmark trials have revolutionized approaches to resuscitation, sepsis, and trauma and have had an impact on many critical care disciplines.

EARLY IDENTIFICATION AND RESUSCITATION OF CRITICAL ILLNESS

One of the most important ED-centered concepts, ushered in by Rivers' landmark study of early goal-directed therapy (EGDT), is that outcomes are improved by early recognition of critical illness and by prompt, aggressive resuscitation.7 An excellent example of this paradigm of timely, structured ED critical care is the current ED sepsis “bundle” of care (i.e., early identification of septic patients, prompt antibiotic delivery, and aggressive hemodynamic resuscitation) endorsed by the Society of Critical Care Medicine and other international organizations.8 ED protocols incorporating sepsis bundles have been shown not only to significantly improve survival outcomes but also to decrease the rate of ICU admission by approximately 11%.2,8

To continue the example, the first step in ED sepsis protocols is rapid identification and risk stratification, which is accomplished using algorithms that incorporate triage vital signs and lactate point-of-care devices.9,10 Following identification of severe sepsis, computer-generated and other automatic flagging systems may speed up and ensure reliable activation of sepsis bundle protocols. To further accelerate this process, EM investigators have recently proposed less invasive alternatives for determining central venous oxygen saturation measurement (SCvO2) and central venous pressure, facilitating implementation of EGDT. In a recent study, clearance of >10% of venous blood lactate was found to be an equivalent resuscitative endpoint as achieving an SCvO2 > 70%, effectively reducing the need for placement of central venous catheters.11 New minimally invasive techniques for assessing intravascular volume status and volume responsiveness have also been introduced, including systolic pressure and pulse pressure variation arterial waveform analysis, physiologic response to passive leg raising, and respirophasic changes in inferior vena cava diameter as measured by bedside ultrasound.1216 ED-based research networks and studies, such as the Protocolized Care for Early Septic Shock (ProCESS) trial, continue to refine optimal emergency sepsis management.17

Structured early identification and risk-stratification protocols have improved ED care for many other critical disease processes as well. Rapid identification of ST-segment elevation MI (STEMI) via point-of-first-contact electrocardiogram analysis is now standard practice in order to reduce reperfusion (door-to-balloon) times. Many emergency medical systems have also implemented prehospital wireless transmission of 12-lead ECGs to facilitate early identification of STEMI patients and timely transport to dedicated cardiac care centers.18

Similarly, in acute stroke management, ED protocols that incorporate early stroke scale examinations are improving diagnosis and management. Many emergency physicians have trained their paramedics to screen patients with abbreviated stroke detection instruments in the field, in order to direct at-risk patients to comprehensive stroke centers for potential reperfusion therapy.19

Improved ED-staging algorithms also help identify patients with impending respiratory failure due to pneumonia, COPD, and other respiratory illnesses.10,20 These tools promote early delivery of appropriate antibiotics, timely initiation of ventilatory support and judicious triage of ICU beds. Analogous to early hemodynamic fluid resuscitation in patients with shock, timely, aggressive respiratory support with non-invasive positive pressure ventilation (NIPPV) in the ED has been shown to improve outcomes and, in many cases, to avert endotracheal intubation and ICU admission.21 Formerly limited to use in patients with COPD, NIPPV has now been shown to decrease respiratory distress and improve outcomes in a broad spectrum of pulmonary disorders.21,22

THE ED–ICU TEAM APPROACH

Protocols emphasizing a team-oriented approach have transformed the delivery of ED critical care. Based on the “golden hour” model of trauma resuscitation, emergency physicians and intensivists have developed ED-based critical care collaborations for treating acute coronary syndrome, stroke, and sepsis. Enhanced communication and structured, automated activation of protocols are the keys to the success of these endeavors. The first step in these protocols is early recognition of critical illness, which ideally begins in the prehospital setting. After recognition of acute disease, prompt notification of key consultants (STEMI team, stroke team, or sepsis team) mobilizes resources and brings critical care personnel to the ED for a timely, orchestrated resuscitation and a smooth transition to the cardiac catheterization laboratory, endovascular suite, or other critical care unit.

Just as ED-derived critical care concepts can benefit ICU practice, so too can ICU-centered concepts improve outcomes in the ED, especially in the setting of extended wait times for transfer to the ICU. For example, with the reported 20% increase in risk of ventilator-associated pneumonia (VAP) per hour spent in the ED, simple ICU VAP reduction measures (head of bed elevation, oral chlorhexidine application, and oral gastric tube decompression) should now be the standard of care in the ED.2628 Likewise, ED application of ICU-derived ventilator management standards, such as ARDSnet protocols, should be fully implemented. The lung-protective ventilation strategies outlined in the ARDSnet protocols have recently been demonstrated to benefit a broader population of patients without adult respiratory distress syndrome, making early consideration of these protocols in a broader ED population a logical extension of ICU care.29

FUTURE DIRECTIONS

The expanded delivery of critical care in the ED opens fertile ground for emergency physician and intensivist research collaboration on a number of unresolved management issues. In sepsis, for example, the best choice (if there is a best choice) of a first-line vasopressor for patients with septic shock has yet to be clearly determined. Similarly, the adrenal suppression effects of etomidate have raised debate as to whether it should continue to be used as an intubation induction agent in patients with sepsis.30,31

A number of unresolved issues also remain for cardiac arrest patients receiving postresuscitation care in the ED. For example, the optimal timing and temperature goals for therapeutic hypothermia (or avoidance of hyperthermia) are unclear, as is the question of whether the neuroprotective benefits extend to patient populations beyond those resuscitated from ventricular fibrillation. Likewise, the potential detrimental effects of postresuscitation hyperoxia and hyperglycemia are undetermined,32 as are optimal blood pressure targets and glucose control in patients with traumatic brain injury. Collaboration between emergency physicians and intensivists will be needed to address these questions.

Optimal care of the critically ill patient begins with early recognition of disease and aggressive resuscitation in the ED, and is followed by a well-coordinated, multidisciplinary effort to facilitate a smooth transition from ED to the ICU. The ED–ICU partnership has never been stronger and will continue to grow as more EM-trained physicians embark on critical care fellowships. This text provides the emergency physician with the foundation necessary to provide our sickest patients with both immediate and ongoing care.

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