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Chad Brocato, CFO, DHSc, JD | Peter P. Taillac, MD, FACEP | From the October 2012 Issue | Thursday, September 27, 2012
Serious hemorrhage from truncal wounds is internal and uncontrollable, and requires EMS providers to assist the body?s natural ability to form a clot.
Photo Edward Dickinson 2013 JEMS Games
In March 2013, a patient suffering from hemorrhagic shock will be among the victims managed at the JEMS Games clinical competition at the EMS Today Conference & Exposition. This comprehensive clinical article will assist participating teams, attendees and readers in understanding this complex medical event and has been accredited by the Continuing Education Coordinating Board for EMS (CECBEMS) for 1 hour of continuing education credit.
For a limited time only, readers of this article may obtain CE credit courtesy of Laerdal Medical Corp. The first 500 visitors to JEMS.com/Discover-Simulation who register using promo code JEMSOctCE (not case sensitive) will receive CE credit free.
In addition, JEMS Games founding sponsor, Laerdal will provide a special ?Discover Simulation? tool kit to each person attending the JEMS Games finals on March 8, 2013. The tool kit offers a turn-key solution to rolling out the simulations featured at the JEMS Games complete with facilitation guide, checklists and other valuable resources to help make simulation training easier.
For more, visit jems.com/Discover-Simulation.
Learning Objectives
>> Identify major anatomical components? of the cardiovascular system.
>> Describe the physiological components? of blood pressure.
>> Differentiate between compensated,? uncompensated, and irreversible shock.
>> Use a comprehensive assessment to? formulate a treatment plan for a patient suffering from shock.
Key Terms
Hemorrhagic shock: Shock associated with the sudden and rapid loss of significant amounts of blood often caused by severe traumatic injuries. This results in inadequate perfusion to meet the metabolic demands of cellular function.
Compensated shock: Category of shock that occurs early, while the body is still able to compensate for a shortfall in one or more of the three areas of perfusion.
Uncompensated shock: Category of shock that occurs when the compensatory mechanisms fail and the patient?s condition deteriorates.
Irreversible shock: The terminal category of shock that will lead to the patient?s demise because it can?t be reversed.
Truncal injury: Injuries pertaining to the chest, abdomen, or pelvis, where hemorrhage can be difficult to detect and control for prehospital providers.
Case Presentation
On a cold, rainy evening, the crew of Rescue 4 is jolted to attention by a dispatcher announcing, ?Respond to a shooting at 7th Street and Main.? The lead paramedic recognizes the address as a location within a community with a long-standing history of violent crimes. Local police have already secured the scene. The EMS crew arrives to note a young male lying in a pool of blood with a visible gunshot wound (GSW) to his right abdomen.
He?s conscious but slow to respond to questioning. The crew quickly assesses his initial airway, breathing and circulation status. Although his skin is cool to the touch, he has a palpable radial pulse. High-flow oxygen is applied while additional assessment is conducted. One crew member quickly performs a rapid head-to-toe exam to discover a second GSW to the left anterior thigh, which is actively hemorrhaging bright red blood. The EMS provider immediately places a tourniquet proximal to the wound and quickly stops the hemorrhage.
When the crew rolls the patient to assess his posterior surfaces and place him on a backboard, they note an exit wound just lateral to the spine at approximately the level of the eighth rib on the right posterior thorax. The exit wound is approximately the size of a quarter. Vital signs include a blood pressure of 108/74, respiration rate of 30 and a pulse rate of 128 beats per minute (bpm) His Glasgow Coma Scale score is 14, and he?s confused about the time and place.
Once inside the ambulance, the patient is quickly reassessed. The lead medic quickly places two peripheral IV lines while the unit is en route to the hospital. During the 15-minute ride, the patient rapidly deteriorates. His blood pressure drops to 74/50; his heart rate increases to 144 and respirations are 38. Suspecting a possible tension pneumothorax, the medic inserts a 14-gauge catheter into the patient?s chest, and a rush of air ensues. The lead medic then administers a 500 cc bolus of normal saline. The patient?s respiratory rate and pulse immediately decrease, and his blood pressure improves to 95/50. The lead medic provides a concise radio report to the hospital and arrives shortly thereafter, having stabilized this critical patient.
Patients with internal or external bleeding are at risk for developing shock. In some cases, such as the one illustrated above, the onset of shock will be rapid. EMS providers need to be able to predict that shock will occur prior to discovering the hallmark signs. This article will address key considerations related to determining the risk of developing shock, detecting shock when it?s present, and providing rapid assessments and interventions to improve patient outcomes.
Anatomy & Physiology
The body meets its metabolic demands through a series of anatomical features and physiological mechanisms. In the context of bleeding and shock, the EMS provider must have a keen awareness of the anatomy and physiology of the cardiovascular system. It?s equally important to understand how the system attempts to compensate during times of injury.
The Heart
The heart is at the core of the cardiovascular system. It?s a four-chambered organ that must constantly pump blood to the lungs and the body as a whole. Blood is received in the two superior chambers, known as the atria. The lower chambers are known as the ventricles. The right atrium gets its blood from the inferior and superior vena cava. The blood is then pumped past the tricuspid valve into the right ventricle, which then ejects blood through the pulmonary valve, into the pulmonary artery, where it?s delivered to the lungs to be oxygenated. The ?fresh? blood will return to the left atrium via the pulmonary veins.
It will then pass through the mitral valve into the left ventricle, which is considered the high-pressure side of the heart. Blood is ejected from the left ventricle past the aortic valve into the aorta. It?s then distributed throughout the body.
Blood Distribution & Composition
The body?s distribution system for blood includes all of the vessels. Arteries, with the exception of the pulmonary artery, deliver highly oxygenated blood throughout the body. These vessels are relatively thick and are composed of three layers: the tunic intima (innermost layer), the tunic media (middle layer), and the tunic adventitia (outermost layer).
The arteries branch off to become smaller vessels, known as arterioles. These smaller vessels bring blood to the capillaries, which are tiny, thin-walled vessels that allow the diffusion of oxygen and nutrients for the benefit of the body?s cells. Waste products are then diffused from the cells into the venous side of the capillaries. Smaller vessels, known as venules, carry this blood to the veins. The venous blood is lower in oxygen but not devoid of it. The veins eventually connect to the vena cava to return the blood to the heart for its next loop in the cycle.
The blood is composed of both fluid and formed elements. The fluid is known as plasma, which contains important proteins, including critical clotting factors. The formed elements include the red blood cells (erythrocytes), white blood cells (leukocytes) and platelets. The leukocytes work to fight off infections. However, more important to learn about in the context of bleeding and shock are the erythrocytes and platelets.
When the system works properly, the body?s cells, tissues and organs are properly perfused. Perfusion is a complicated process that can be simplified down to this critical point: in order for the cells to function properly, they need an adequate flow of oxygen and nutrients coupled with the need to eliminate harmful waste products. Perfusion is accomplished when the heart, blood vessels and blood are working in harmony. Thus, the heart must be functioning, the blood vessels must have proper tone (resistance), and an adequate amount of blood must be present. EMS providers roughly measure perfusion by assessing blood pressure. Mathematically, blood pressure is a product of heart rate multiplied by stroke volume multiplied by peripheral vascular resistance.
The heart rate must be adequate to ensure proper blood flow. The average adult heart rate is between 60?100 bpm while at rest. Significant decreases or increases in the heart rate have a direct impact on perfusion.
Stroke volume is the volume of blood pumped from each ventricle with each beat and is typically 70 mL for the average adult male. Stroke volume can be decreased by such factors as increased resistance, improper functioning of the heart or valves, and inadequate blood volume.
Peripheral vascular resistance is the tone in the blood vessels. Because our bodies must constantly fight the forces of gravity and pump the blood throughout the body, the vessels need to have some pressure or ?squeeze.? If all of your vessels were to dilate, your blood pressure would plummet as the blood would pool to the areas where gravity pulled it. So the peripheral vessels maintain this tone in order to equalize the effects of position changes (gravity) and to ?fine tune? the blood pressure second?to second.
Under normal conditions, the entire system works in concert to ensure that the blood flows to all organs, tissues, and cells. When the body has been compromised, such as when hemorrhage from a gunshot wound occurs, it will attempt to compensate for any reductions.
For example, if the blood pressure falls, the heart will respond by pumping faster and with more force, and the vessels will constrict and reroute blood from peripheral areas to the core in an effort to preserve the vital organs. Thus, prehospital caregivers should consider any factors that would reduce the overall flow of blood as they relate to heart rate, stroke volume and peripheral vascular resistance.
If external or internal bleeding is present, the stroke volume will obviously be affected because of the lost blood. If the patient has a rapid heart rate, then the volume and resistance will need to increase to ?compensate? for the change. If the blood vessels lack adequate tone, the heart rate will need to increase as will the force of contractions. It?s important to understand the interconnectedness of the heart rate (HR), stroke volume (SV) and peripheral vascular resistance (PVR).
Pathophysiology
Simply stated, shock is a state of inadequate perfusion. Hemorrhagic shock occurs when, as a result of acute blood loss, cells are negatively impacted because they are inadequately perfused. Therefore, they don?t receive an adequate supply of oxygen or removal of wastes.
Three types of shock exist: compensated, uncompensated, and irreversible. The prehospital provider can have the greatest effect if shock can be prevented, by preventing blood loss. If this isn?t possible because of factors beyond the provider?s control, then caregivers should act quickly to keep compensated shock from becoming uncompensated shock. All efforts should be undertaken to avoid irreversible shock.
Compensated shock occurs early while the body is still able to compensate for a shortfall in one or more of the three areas of perfusion (HR, SV, and/or PVR). The signs and symptoms of this stage of shock include tachycardia and tachypnea, as well as cool pale, and diaphoretic skin. The patient?s blood pressure may be within normal ranges during compensatory shock. Mental status may also be normal during this early stage.
Uncompensated shock occurs when the compensatory mechanisms fail, and the patient?s condition deteriorates. The hallmark sign of uncompensated shock is a reduction in blood pressure. Other signs include decreased mental status, tachycardia, tachypnea, thirst, reduced body temperature and skin that is cool, sweaty and pale. If untreated or inadequately treated, the patient may lapse into irreversible shock. As its name implies, this latter category of shock will lead to the patient?s demise because it can?t be reversed.
New Concepts
Now back to our gunshot victim. How do we prevent the cascade of physiologic events that leads to the irreversible shock state? The key is prevention of shock in the first place. EMS providers are in a critical position because their actions in the first hour after injury, often called the ?Golden Hour? (or ?Platinum 10 Minutes?) can mean the difference between a stable patient and one who rapidly develops an uncompensated and then irreversible shock state, resulting in death.
Research from trauma centers and experience from the battlefields of Iraq and Afghanistan have suggested new approaches to both the avoidance and the management of shock in the prehospital environment. Extremity injuries are addressed with immediate control of hemorrhage, with a pressure dressing or a tourniquet. For patients with a truncal injury (wound to chest, abdomen or pelvis) careful and judicious fluid administration in the field can help minimize hemorrhage and preserve critical blood volume, thus giving the patient a better chance to make it to the operating room where such internal bleeding can be directly controlled.
Aggressive and lifesaving EMS care for this shooting victim begins with a rapid but thorough assessment of his wounds. This requires visualization and palpation of the entire torso and extremities for wounds. This patient in this example demonstrates a penetrating wound to abdomen with an exit wound posteriorly at approximately the eighth rib level, which raises the possibility of a chest injury, such as a tension pneumothorax.
Rolling the patient to evaluate posterior wounds is a critical step that can be easily missed in the evaluation of a shooting victim. In this case, this revealed a wound that may compromise pulmonary and cardiac function. In addition, an actively bleeding thigh wound is noted as part of the head-to-toe exam.
The management of these wounds (extremity and torso) requires prompt action on the part of the medic to avoid the onset of shock, to minimize internal bleeding, and to address the rapid deterioration of the patient. The two torso wounds aren?t visibly bleeding; however, it?s assumed there may be significant internal hemorrhage.
First, the EMS provider immediately stops the rapid blood loss from the thigh wound by the prompt application of a tourniquet proximal to the wound. This rapid and simple intervention may be lifesaving by preventing the onset of shock. Research from battlefield injuries in Iraq demonstrates a nearly 25-fold (96% vs. 4%) improvement in survival when hemorrhage was controlled by tourniquets prior to the onset of shock.
Depending on the status of the patient and the transport time, this tourniquet can either be left in place until arrival at the emergency department (ED) or, if possible, replaced by an effective pressure dressing.
If a tourniquet is left in place, the EMS provider must alert the ED personnel that a tourniquet is in place, so it isn?t overlooked while the other, more obvious, wounds are managed. If a pressure dressing is placed, then the tourniquet should be left loosely in place and the thigh wound frequently re-evaluated by the EMS provider for continued bleeding. Then, if bleeding recurs, the tourniquet can then be simply re-tightened.
Once the thigh hemorrhage is stopped, the medics placed two large bore IVs. This has been a recommended practice in early trauma management for decades. However, although the placement of such ?lifelines? is still recommended to provide access for medications and fluids, newer research indicates that less IV fluid may be better for truncal wounds. Serious hemorrhage from truncal wounds is internal and uncontrollable by the medic in contrast to extremity wounds, which present with external hemorrhage and are controllable, with direct pressure or a tourniquet.
For internal hemorrhage, the medic must assist the body?s natural ability to form a clot. Research indicates that this clot formation is disrupted by rapidly increasing the BP with crystalloid IV fluids, such as normal saline. In addition, crystalloid dilutes the clotting factors that are critical to formation and strengthening of these fragile clots. Based on this research, the new recommendation is ?don?t pop the clot? by the use of excessive IV fluid in the field. For patients with internal bleeding who aren?t in uncompensated shock (their systolic BP is greater than 80?90 mm/Hg, or a radial pulse is present and mentation is normal), IV fluids should be withheld until the patient can receive definitive control of this internal hemorrhage in the operating room.
Resuscitation studies demonstrate that this strategy minimizes hemorrhage and subsequent transfusion requirements. However, in the case of a patient who is demonstrating signs of uncompensated shock (systolic BP is less than 80?90, or the patient has a loss of radial pulse or decreasing mentation), administration of judicious boluses of crystalloid to support the blood pressure may be required to get the patient to the ED alive. Administration of boluses of 500?1,000 cc at a time, with reassessment after each bolus to keep the systolic BP above 80?90 mm/Hg is recommended. This strategy of minimizing IV fluid by such calibrated boluses is contrasted with our former practice of indiscriminately administering large volumes of IV fluid to all trauma patients.
Lastly, the patient initially had a systolic BP of 108, but then rapidly decompensated, demonstrated by worsening hypotension and increasing tachycardia and tachypnea. The astute medic realized that, with a possible chest wound, this patient may be manifesting a tension pneumothorax. In this condition, the pneumothorax enlarges progressively, increasing pressure in the chest to the point that the return of blood to the heart is compromised, resulting in decreased SV, and a shock state ensues. The immediate and lifesaving treatment is to decompress the tension pneumothorax by placing a large-bore IV catheter in the second intercostal space in the mid-clavicular line.
This results in an immediate decrease in the intrathoracic pressure and improvement in venous blood refilling the heart, restoring SV and cardiac output. Our medics recognized and treated this patient with chest decompression followed by a calibrated 500 cc bolus of crytalloid, with improved vital signs found on reassessment. These medics prevented the onset of irreversible shock and saved this patient?s life with their prompt and expert interventions.
Conclusion
New concepts in trauma management differentiate between controllable hemorrhage from extremities and uncontrollable internal hemorrhage from truncal injuries. The goal of trauma management is the prevention of uncompensated and irreversible shock.
Prompt control of blood loss from extremities with a pressure dressing or a tourniquet is an immediate priority and should be implemented during the primary survey of the trauma patient. Internal bleeding control from truncal injuries is facilitated by ?not popping the clot.? These patients may be managed in their compensated shock state (BP above 80?90 mm/Hg) by avoiding excess prehospital IV fluids. Judicious and calibrated IV boluses are used to support the BP below this level.
Last, remember that a penetrating chest injury in the face of shock may represent a tension pneumothorax and require immediate needle thoracostomy to restore cardiac output. JEMS
References
1. Kragh J, Littrel M, Jones J, et al. Battle casualty survival with emergency tourniquet use to stop limb bleeding. J Emerg Med. 2011;41(6):590.
2. Bickell W, Wall M, Pepe P, et al. Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries. N Eng J Med.1994;331(17):1,105.
3. Taillac P, Doyle G. Tourniquet first! Safe and rational protocols for prehospital tourniquet use. JEMS.2008(Oct Suppl);24.
4. Butler F, Holcomb J, Giebner S. Tactical combat casualty care 2007: Evolving concepts and battlefield experience. Mil Med. 2007:172(suppl 1):1.
5. McSwain N, Champion H, Fabian T, et al. State of the art fluid resuscitation 2010: Prehospital and immediate transition to the hospital. J Trauma 2011;70(5)(supplement):S2.
Source: http://www.jems.com/article/patient-care/ems-providers-should-improve-their-abili
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