Each year, in the United States, more than 2.5 million people are killed or hospitalized as a result of traumatic injuries. Over one quarter of these patients are treated in an intensive care unit (ICU) at some point during their hospital stays. With mortality rates exceeding 20% for the most severely injured patients (injury severity score [ISS] > 25), it stands to reason that the delivery of high-quality health care to trauma patients in an ICU setting plays a paramount role in their resuscitation and recovery.
Infrastructure
The first step in the provision of high-quality trauma ICU care is delivery of the trauma patient to an ICU capable of rendering that care. In this regard, trauma patients should be cared for at hospitals with specialty trauma services. Population-based estimates have demonstrated a relative risk (RR) for mortality of 0.80 (95% confidence interval [CI], 0.66 to 0.98) for trauma patients treated at trauma centers compared with case mix-matched patients treated at nontrauma centers. Multiple studies have confirmed this model of care as successful and cost effective. There remains debate regarding the source of this outcome advantage. Specifically, it is unclear whether the advantage derives from the absolute volume of the trauma center or the level of trauma center designation (and the resources associated with that designation).
There is much less uncertainty about the role of intensivists in caring for these patients. In 2006, Nathens and colleagues demonstrated that, when compared with “open” ICUs, the intensivist model was associated with an RR of death of 0.78 among trauma patients in a large multicenter prospective cohort study. This effect was more pronounced among elderly patients (RR of death, 0.55), in ICUs in trauma centers (RR of death, 0.64), and in units directed by surgically trained intensivists (RR of death, 0.67). Similar data have shown not only improved mortality but also lower ICU mortality, lower ventilator-associated pneumonia rates, and increased ventilator-free days among ICUs that actively engage intensivists in the care of trauma patients. This model has been expanded to trauma care in the combat zone, with favorable effects on morbidity and mortality among combat-injured patients cared for by intensivists.
Finally, perhaps the most important factor contributing to the better care afforded by trauma centers and staffed with specifically trained personnel is the availability of ICU beds themselves. Emergency department lengths of stay continue to increase, and much of the early part of resuscitation occurs within the confines of the emergency department or the trauma bay. Providing ICU-level care within the trauma bay can be a challenging task. Evidence suggests that emergency department length of stay is directly linked to increased rates of pneumonia and death. One response to this problem is implementation of an “open trauma bed” protocol to improve throughput from the trauma bay. In this study sample, the emergency department length of stay was decreased by nearly 1 hour after the protocol was instituted. Other investigators have demonstrated similar results, supported by cost-effectiveness data, by staffing an open ICU bed with an otherwise unassigned charge nurse. However, it remains unclear how these protocols affect patients who are displaced from the ICU to generate bed availability.
Resuscitation
The primary goal of the intensivist caring for a trauma patient should be the recognition of shock and the implementation of resuscitation strategies to capture and reverse the associated abnormal physiology. The diagnosis of shock must be made with a high clinical index of suspicion because ongoing occult hypoperfusion (which occurs in up to 85% of severely injured trauma patients) has been associated with increased morbidity and mortality. Several modalities of quantifying resuscitative efforts beyond standard vital signs have been proposed. They can be classified broadly into invasive monitors (such as pulmonary artery [PA] catheters, peripheral arterial catheters, and gastric tonometers), noninvasive monitors (such as bedside ultrasonography and bioreactance monitoring), and biomarkers (such as arterial or venous lactate, base deficit, and arterial or mixed venous oxygen saturation).
Invasive Hemodynamic Monitoring
Optimal oxygen (O 2 ) delivery relies heavily on adequate cardiac performance. Therefore, optimization of cardiac output (CO) is a key feature of any resuscitative effort. Historically, PA catheterization was the mainstay of invasive hemodynamic monitoring. However, routine use of these devices has become less common, and they seem most efficacious among older trauma patients and those who arrive in severe shock.
Several commercially available products are available to estimate CO with less intrusion than PA catheterization. For instance, the lithium indicator dilution technique utilizes central venous catheterization and cannulation of the femoral or axillary artery to measure heart function. Similarly, there exist proprietary algorithms capable of estimating CO via transpulmonary thermodilution methods. Finally, volume responsiveness based on stroke volume variation transduced by a peripherally inserted arterial catheter can be calculated by several devices. Although all of these systems show promise in regards to their low complication rates, their efficacy in guiding fluid resuscitation of trauma patients remains unknown. Animal hemorrhagic shock models suggest that these devices might be unreliable, most commonly underestimating CO. It is conceivable that as these technologies evolve, they will be capable of estimating cardiac function similar to pulmonary arterial cannulation without the need to traverse the right side of the heart and dwell within the pulmonary arterial system.
Noninvasive Hemodynamic Monitoring
Impedance cardiography and bioreactance are two methods of quantifying cardiac function without invasive monitoring. Both methods use electrophysiology to measure how changes in aortic blood volume and flow influence transmission of a known electrical current across the thorax. These technologies have been studied in multiple ICU settings and show modest correlation with traditional PA catheter thermodilution. To date, there is one prospective observational study of this technology in trauma patients, demonstrating an association of bioreactance monitoring and shortened hospital length of stay. However, it should be noted that the comparison groups were historic controls, and changes in hospital admission and discharge practices might have confounded the analysis.
Ultrasonography has been used as a triage tool in the trauma bay for many years and has recently become an important test for the intensivist who cares for trauma patients. Several investigators have shown that bedside ultrasonography of the cava and heart can demonstrate hypovolemic shock and the response to plasma expansion. Most of these studies are limited by their retrospective nature; however, a recent randomized trial indicated that use of limited transthoracic echocardiograms during trauma resuscitation was associated with decreased intravenous fluid administration and improved survival. Confirmatory studies are required. However, the repeatability, relatively low cost, and noninvasiveness of this diagnostic tool seem promising.
Biomarkers
The mainstay of trauma resuscitation has been biochemical endpoints of resuscitation. Although many have been investigated, the two that have been most useful in caring for trauma patients are serum lactate and base deficit. Both of these tests are sensitive measures of hypoperfusion ; however, the interpretation of these tests can be clouded by hepatic and/or renal dysfunction. Abnormal lactate and base deficit have been associated with morbidity and mortality. Measurement of lactate and base deficit might be useful guides for resuscitative progress because mortality has been associated with increased time to normalization of serum lactate. Likewise, in one study of trauma patients with increasing base deficit despite resuscitation, 65% were found to have ongoing hemorrhage, suggesting the potential utility of this test as an adjunct to the resuscitative efforts. The most recent recommendation on the topic developed by the Eastern Association for the Surgery of Trauma suggests using at least one of these measures to quantify the need for ongoing resuscitation.
There is mounting evidence that these studies, performed as point of care (POC) tests, decrease the time to diagnosis and intervention, reduce the total volume of blood draws, and shorten ICU lengths of stay. POC thromboelastography can also be considered to help guide blood product administration during resuscitation in the trauma bay as well as the ICU.
Special Considerations of Shock
Hypovolemic Shock
Hypovolemic shock from uncontrolled hemorrhage is the quintessential form of shock among trauma patients. Much work has been done to advance the care of trauma patients, both in control of hemorrhage (permissive hypotension, fluid restrictive resuscitation, damage control surgery, applications of tourniquets, topical hemostatic agents, endovascular occlusion, etc.) as well as replacement of intravascular volume (colloid, isotonic and hypertonic crystalloid, balanced salt solutions, blood products, massive transfusion protocols, etc.). Details of these techniques can be found elsewhere in this text. Suffice it to say that mastery of hemorrhage control and fluid resuscitation is critical to the cessation and reversal of hemorrhagic shock.
Septic Shock
Trauma patients with septic shock should be cared for according to the Surviving Sepsis Guidelines. Although no studies, to date, have demonstrated any outcome advantage in particular to trauma patients, this body of work remains the most comprehensive summary of sepsis management in most patients. Particular mention should be made of two details. First, source control can be particularly challenging in trauma patients with multiple injured systems. Practitioners must rely heavily on physical examination, coupled with various methods of diagnostic imaging to guide interventions. This is particularly true in hostile abdomens and thoraces, in which some patients will undoubtedly benefit from percutaneous drainage rather than more traditional surgical exposures. Second, antibiotic stewardship is fundamental to trauma ICUs. The data supporting de-escalation of antibacterial therapy as a means of quelling antibiotic resistance are lacking. However, the recent emergence of increasingly resistant organisms coincident with the common practice of empiric broad-spectrum antibiotic therapy lends strong credence to a linkage between these phenomena. Consequentially, strong consideration should be given to narrowing antibacterial coverage when culture data are available in appropriate patient groups. There is no evidence that trauma patients (even those with much “spillage” or “contamination”) benefit from extended empiric coverage. Likewise, the “open abdomen” strategy of patient care does not necessarily mandate use of antibiotics in the absence of other indicators of infection.
In addition, those practitioners who care for trauma patients must remain vigilant for signs of severe sepsis or septic shock through the duration of each patient’s encounter. Either might very well be the inciting event that leads to a patient’s trauma and admission, or it might very well bring a trauma patient back to the hospital from inpatient physical therapy, skilled nursing, or even home. And patients remain susceptible to the diagnosis at every point in between.
Neurogenic Shock
The incidence of neurogenic shock in patients with cervical spinal cord injuries is 20%. The optimal treatment of the bradycardia and hypotension that define this pathophysiology remains unknown, but treatment with intravascular volume expansion as well as pharmacologic management with vasoactive, chronotropic, and inotropic medications might be indicated. On occasion, the use of electrical cardiac stimulation, by way of percutaneous or intravascular pacers, might be valuable. Therefore, the ICU should be capable of managing these various modes of hemodynamic support for patients with this injury complex.
Cardiogenic Shock
The combination of increasing age among trauma patients and higher numbers of high-speed motor vehicle accidents has contributed to increasing numbers of clinically significant cardiac injuries. It is estimated that up to 20% of road traffic deaths are associated with blunt injuries to the heart. Recognition of cardiac compromise can be challenging because many of these patients suffer concomitant injuries resulting in mixed shock physiology. Signs of systemic hypotension in the face of elevated central venous pressure should raise concern for cardiogenic shock. Otherwise, clinicians must maintain a high index of suspicion based on the mechanism of injury despite potentially silent clinical signs. Patients with suspected blunt cardiac injury should be screened with electrocardiogram and troponin I. The negative predictive value of these combined tests approaches 100%. The care of patients with cardiogenic shock is detailed elsewhere in this text. The care of trauma patients, in particular, must be guided by experienced traumatologists, in consultation with cardiologists, weighing the risks and benefits of interventions in the setting of potentially competing priorities.
Special Considerations of Trauma Patients
The Open Cavity
The use of damage control surgery and resuscitation has resulted in many critically ill trauma patients presenting to the ICU with open body cavities. It is not unusual for patients to spend days recovering from the initial physiologic insult before these cavities can be closed. In this regard, it is paramount that ICUs specializing in the care of trauma patients be familiar with management of severe biomechanical and physiologic derangements that occur as chest and abdominal wall geometry are altered. Advanced modes of mechanical ventilation might be necessary for patients with packed thoraces. Likewise, the open abdomen might require skilled nursing wound care with negative pressure dressings and supplemented nutritional strategies for gastrointestinal drainage and discontinuity.
Traction/Immobility
Damage control orthopedic surgery (early external fixation followed by definitive treatment) has become increasingly common among polytrauma patients. Therefore, the number of patients with large external fixation devices in the ICU has increased. Likewise, ICU patients might be cared for with pelvic stabilization devices (sheets and commercially available pelvic binders) and/or spinal column stabilizing devices (cervical spine bracing devices such as cervical collars or Halo systems, thoracolumbosacral orthosis braces). Although these techniques are helpful to the recovery of various injuries, they oftentimes limit mobility and access to soft tissue care. Therefore, particular attention must be paid to these trauma patients to ensure adequate wound care and prevention of the secondary complications of immobility.
Venous Thromboembolism Prophylaxis
Venous thromboembolism (VTE) is a common complication in patients with major trauma. The risk is compounded by various factors, such as the systemic inflammatory response to major trauma, immobility, and the hypercoagulable state associated with major surgery, bone fractures, and the use of invasive vascular devices. It is important for the ICU to practice aggressive evaluation for VTE with protocolized care to help prevent the (potentially fatal) sequelae of VTE. Implementation of VTE prevention strategies in the form of “smart order sets” or risk assessment models has been associated with decreased rates of radiographically documented VTE (2.5% vs. 0.7%) and a 39% RR reduction of hospital-acquired VTE in some patient groups. Clinicians must also be familiar with evidence-based best practice guidelines to help reduce VTE risk, particularly for trauma patients.
Intensive Care Unit Protocols
Guideline-based care (in the form of agreed-upon practice patterns, guidelines, or protocols) plays an important role in the delivery of high-quality intensive care therapies to patients with traumatic injuries. Studies have demonstrated that implementation of trauma systems, including things such as early management guidelines and consensus-developed clinical practice guidelines and protocols, are associated with decreasing odds of death (odds ratio [OR] 0.45; 95% CI, 0.27 to 0.76), standardized care, and improved resource utilization. They are natural extensions of the algorithmic approach to the triage of life-threatening injuries suggested by the Advanced Trauma Life Support (ATLS) curriculum. It is impossible to list every ICU trauma guideline within the context of this chapter, but consideration should be given to several management strategies. Indeed, this approach has been advocated for management of, among others, elevated intracranial pressure, spinal cord injury and rehabilitation, sedation and delirium, pain control, mechanical ventilation and weaning, use of enteral and parenteral nutrition, glucose control, utilization of bladder catheters, blood transfusions, antibiotic stewardship, prophylaxis of stress ulcers and venous thromboembolic disease, early mobilization and physical therapy, and use of various ICU devices (such as central and peripherally inserted catheters, arterial lines, and ICU specialty beds). Importantly, virtually none of these interventions is based on high-level evidence. However, the central theme of the guidelines (i.e., that improved outcomes for injured patients) can be obtained through better organization, and planning of trauma care should be maintained. Some researchers have found that major deviations from clinical management guidelines are associated with a 3-fold increase in mortality among trauma patients (adjusted OR 3.28; 95% CI, 1.53 to 7.03). Similarly, an intervention as simple as strict adherence to a daily rounding checklist has been linked to improved outcomes, such as decreased ventilator-associated pneumonia rates, relative to partial compliance with the same checklist (3.5% vs. 13.4%, P = .04).
Tertiary Examination
A common pitfall of caring for trauma patients (particularly those who are critically ill) is failure to recognize missed injuries. This results from many variables, including severe physiologic derangements, inability of the patient to participate in the history and physical examination, handoffs of care, and multiple service lines assuming care of different injury complexes. So-called “missed injuries” can result in significant morbidity and even death. Several mechanisms have been proposed to help decrease the rate of missed injuries. Most are extensions of the tertiary survey proposed by Enderson in 1990. Technologic advances should also help to reduce missed injury rates as faster and more detailed medical imaging becomes increasingly affordable and mobile. Access to electronic medical records and the use of handheld communication devices and electronic checklists should also help expedite recognition and communication of previously undocumented injuries.
Related posts:
What Lessons Have Intensivists Learned During the Evidence-Based Medicine Era?
What Is the Role of Invasive Hemodynamic Monitoring in Critical Care?
Should Fever Be Treated?
Are Computerized Algorithms Useful in Managing the Critically Ill Patient?
Inhaled Vasodilators in ARDS: Do They Make a Difference?
How Can We Monitor the Microcirculation in Sepsis? Does It Improve Outcome?
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