EMERGENCY 1.5 HOURS CE Continuing Education Trauma-Related Hemorrhagic Shock: A Clinical Review Assessment and management of this life-threatening emergency. ABSTRACT: Optimal management of trauma-related hemorrhagic shock begins at the point of injury and continues throughout all hospital settings. Several procedures developed on the battlefield to treat this condition have been adopted by civilian health care systems and are now used in a number of nonmilitary hospitals. Despite the important role nurses play in caring for patients with trauma-related hemorrhagic shock, much of the literature on this condition is directed toward paramedics and physicians. This article discusses the general principles underlying the pathophysiology and clinical management of trauma- related hemorrhagic shock and updates readers on nursing practices used in its management. Keywords: hemorrhagic shock, hypovolemia, resuscitation, trauma nursing, traumatic injury emorrhagic shock remains a primary cause ing practices currently incorporated in civilian as of death from traumatic injury.1 Although well as military settings, many of which are based Hnurses—particularly those who work in emer- on procedures established on the battlefield and gency medical services, trauma centers, and ICUs— outlined in the Tactical Combat Casualty Care are vital to the assessment and successful management (TCCC) Guidelines, a set of evidence-based guide- of traumatic hemorrhage and subsequent shock, the lines for providing care to injured patients in a pre- vast majority of literature on the subject has been hospital or battlefield setting.10 directed at paramedics or physicians.2-8 In 1908, Marie Louis published an article in AJN THE PATHOPHYSIOLOGY OF HEMORRHAGIC SHOCK that discussed the typical signs and symptoms of hem- Shock occurs when there is an imbalance between orrhagic shock and the lifesaving interventions nurses oxygen delivery to and consumption by the tissues.11 should perform in such cases (see https://journals.lww. Based on its root cause, shock can be classified into com/ajnonline/Citation/1908/09000/THE_NURSE_ one of four subtypes: hypovolemic, cardiogenic, S_MANAGEMENT_OF_SHOCK_AND_HEMO obstructive, or distributive.12 RRHAGE.13.aspx).9 Since that time, the medical Hypovolemic shock occurs when inadequate vol- community’s understanding of hemorrhagic shock ume within the vasculature reduces perfusion pres- and its management has evolved, based in large part sure to insufficient levels. This may result from on insights gained through military operations in severe dehydration or blood loss related to medical Afghanistan and Iraq. conditions or traumatic injury. Hypovolemic shock This article reviews the pathophysiology of hem- brought on by blood loss is called hemorrhagic shock. orrhagic shock and discusses the laboratory studies, Several compensatory mechanisms activated at diagnostic tests, resuscitation principles, and nurs- the onset of trauma-related hemorrhage maintain 36 AJN ▼ September 2020 ▼ Vol. 120, No. 9 ajnonline.com By Nicole W. Caldwell, BA, AAS, RN, Mithun Suresh, MD, Tricia Garcia-Choudary, MPH, BSN, RN, and Christopher A. VanFosson, PhD, MHA, RN perfusion to vital organs.13 Arterial baroreceptors respond to reduced blood volume by activating the sympathetic nervous system and triggering the release of circulatory vasoactive hormones.14 This sympathetic response constricts peripheral arteries, increases heart rate, and shunts blood to the organs most vital to survival. Both increased vascular resis- tance and elevated heart rate are important in main- taining organ and tissue perfusion.15 If hemorrhage persists, shock follows. When cir- culatory volume becomes too low to maintain a perfusion pressure adequate to sustain tissue oxy- genation, cellular respiration, the process by which cells convert food into usable energy, shifts from aerobic to anaerobic metabolism and lactic acidosis ensues.11 See Figure 1. Avoiding acidosis is critical, as it reduces the body’s ability to form effective clots.16 Moreover, the resultant coagulopathy may be exacerbated by hypothermia, which frequently occurs after massive blood loss, secondary to reduced tissue perfusion and oxygenation. In patients treated for trauma, the com- bination of acidosis, coagulopathy, and hypother- mia is frequently referred to as the “trauma triad of 17 death.” Multisystem organ failure may follow the Medical Center. Army Brooke Becker, Tyson Col. by Photo triad, leading to extremely high rates of mortality.18 LABORATORY STUDIES Systemic markers of global tissue perfusion status Laboratory measurements play a critical role in the such as elevated lactate and base deficit or excess assessment and care of patients following trauma- have been studied extensively in trauma manage- related hemorrhage. A blood type and screen with ment and serve both diagnostic and therapeutic crossmatching should be performed immediately so purposes. They can be used to detect occult tissue that the blood bank can begin processing any blood hypoperfusion, which can occur in the presence of products that may be needed for transfusion. normal vital signs.23-25 Abnormal parameters are Coagulation parameters, such as prothrombin greater than 2 mmol/L for elevated lactate, less than time (PT) or international normalized ratio (INR), –2 for base deficit, and greater than 2 for base activated partial thromboplastin time (aPTT), excess.26 Once resuscitation is underway, these mark- fibrinogen, and platelets, provide a means of esti- ers may be used as end points; delays in normaliza- mating the severity of a patient’s condition.8 In par- tion are associated with poor outcomes. It’s impor- ticular, when the following thresholds are reached, tant to note, however, that a number of ingested resuscitation with the appropriate blood products substances can affect these systemic markers. Etha- (fresh frozen plasma, cryoprecipitate, or platelets, nol, for example, increases lactate levels. Addition- for example) should be initiated to minimize the ally, laboratory studies suggest that the rise in lactate risk of microvascular bleeding19: levels may be only minimal during the early stages • PT, INR, or aPTT more than 1.5 times the nor- of progressive central blood volume loss.27 mal laboratory value • platelets less than 50 to 100 x 109/L–1 THE ROLE OF DIAGNOSTIC IMAGING IN TRAUMA • fibrinogen concentration less than 1 g/L–1 Diagnostic imaging is used in trauma management Thromboelastography (TEG) and rotational to discover and determine the severity of injuries, as thromboelastometry (ROTEM) are novel assays well as to detect bleeding and identify potential that measure the viscoelastic properties of blood sources of bleeding. and can be used at the bedside to monitor and man- Plain film X-rays are easily accessible; quick to age trauma-induced coagulopathy.20 Both can pro- allow visualization of orthopedic injuries and lung vide data that aid in assessing coagulopathy in as fields; and often able to provide indirect evidence of few as 15 to 30 minutes.21, 22 hemorrhage, such as hemothorax. [email protected] AJN ▼ September 2020 ▼ Vol. 120, No. 9 37 Figure 1. The Pathophysiology of Hemorrhagic Shock Activation Release of Decreased Shunting of Onset of Reduction of vasoactive ring of blood from blood loss or in blood sympathetic hormones, arterial nonvital to hemorrhage pressure nervous tachycardia, baroreceptors vital organs, system vasoconstriction maintenance of adequate blood and perfusion pressure Ongoing blood loss or hemorrhage, causing a reduction in tissue perfusion pressure and oxygenation Multisystem organ Ongoing coagulopathy Cellular respiration failure follows the Lactic acidosis is exacerbated further shifts from aerobic to triad of acidosis, begins by acidosis and anaerobic metabolism coagulopathy, and developing hypothermia hypothermia When trauma causes significant blood loss, the body’s compensatory mechanisms (top row, green) attempt to compensate for the ini- tial drop in blood pressure. If, despite their efforts, tissue oxygenation falls too low, cellular respiration shifts from aerobic to anaerobic metabolism (bottom row, red), and the resulting lactic acidosis can exacerbate coagulopathy and lead to multisystem organ failure. The focused assessment with sonography for • thorax (mediastinal or chest wall injuries causing trauma (FAST) examination, however, is often pre- a hemothorax, for example) ferred for early assessment of traumatic injury • abdomen (solid organ injuries causing intraperi- because it toneal or retroperitoneal bleeding, for example) • allows for rapid detection of hemoperitoneum. • pelvis (pelvic fractures causing vascular injuries, • is noninvasive. for example) • can be reproduced. • extremities (femoral fractures causing compart- • uses no radiation. mental bleeding, for example) • can be easily performed at the bedside. Although blood loss is frequently obvious with The accuracy of the FAST exam, however, is injuries to these regions, occult hemorrhage may highly dependent on the user’s skill and training. also occur, so it’s important for nurses to assess and Furthermore, false-positive findings may result if closely monitor injuries when caring for patients fluid from nontraumatic sources is in the abdomen.28 with traumatic injury. Computed tomography (CT) can provide Hemorrhage from blunt injury may be more detailed images of internal cavities and organs, as challenging to detect than hemorrhage from pene- well as of the vasculature. Whole-body