Control of external hemorrhage in trauma patients

INTRODUCTION — Uncontrolled hemorrhage due to trauma remains the leading cause of preventable trauma death among Americans aged 1 to 46 years, with nearly half dying before reaching the hospital for definitive care [1,2]. Firearm violence and mass shootings in the United States have focused attention on this issue and the need for prompt treatment of uncontrolled hemorrhage, but it is important to recognize that more common events such as motorcycle crashes, pedestrians struck, and industrial injuries can all result in significant external hemorrhage requiring immediate intervention.

A stepwise approach to managing hemorrhage involves assessing the location, type, and severity of bleeding and implementing various techniques for hemorrhage control. The best resources for some techniques are typically found in the combat or hospital setting; however, the basic principles can also be applied in the civilian prehospital setting with minor modifications.

Control of external hemorrhage in trauma patients is reviewed. Control of external hemorrhage may be needed in other circumstances (eg, severe postoperative bleeding) and follows a similar approach.

Initial management of the trauma patient, hemodynamic resuscitation, and damage control and resuscitation strategies are reviewed separately.

●(See "Initial management of trauma in adults".)

●(See "Initial management of moderate to severe hemorrhage in the adult trauma patient".)

●(See "Overview of damage control surgery and resuscitation in patients sustaining severe injury".)

●(See "Ongoing assessment, monitoring, and resuscitation of the severely injured patient".)

PREHOSPITAL CARE SETTING — Exsanguination remains the leading cause of preventable death among victims of trauma. Nearly half of these mortalities occur in the prehospital setting. While emergency medical services (EMS) play a huge role in immediately stopping external hemorrhage, there have been more focused efforts through the Stop the Bleed Campaign to empower civilians who witness such severe injuries. These "immediate responders" are being taught to apply pressure, pack wounds, and even place tourniquets for uncontrolled hemorrhage.

Military response to casualty events — The first known use of an extremity tourniquet was in the Middle Ages, when a tourniquet was used at the Battle of Flanders in 1674. Tourniquets have been used in military combat ever since [3]. The success of the tourniquet in saving lives in combat led to their use in civilian populations. Tourniquets were frowned upon in WWII due to the excessive length of time they were left in place, which was associated with high amputation rates. This distrust of the tourniquet transferred to the civilian setting, where EMS providers were taught to avoid using tourniquets as late as the early 2000s. However, tourniquets were used successfully in combat in Iraq and Afghanistan with improved mortality, and after these conflicts, the tourniquet was commercialized and introduced in civilian EMS and law enforcement with success [4].

Civilian response to casualty events — Firearm violence and active shooter/mass casualty events remain a difficult problem. To improve survival, there has been increasing interest in the use of tourniquets to control extremity hemorrhage [5-7]. Guidelines include tourniquet application as a temporary adjunct to control extremity hemorrhage when direct pressure is unsuccessful [8-10], and during tactical civilian events, which are situations when ballistic or explosive wounds are possible (eg, active shooter standoff) [11].

Implementation of early hemorrhage control strategies as described in the Stop the Bleed public initiative [12], and those described in the Hartford Consensus are paramount [13].

Stop the bleed — An emergency physician (Peter Pons), a member of the Prehospital Trauma Life Support (PHTLS) committee of the National Association of Emergency Medical Technicians (NAEMT), is credited with the initial idea to develop a curriculum focused on control of bleeding similar to cardiopulmonary resuscitation, which prepares bystanders for a cardiac emergency. Working with the medical director of PHTLS (Norman McSwain), and a liaison to the American College of Surgeons Committee on Trauma (ACS-COT) at the time, they developed a course that addressed this need. Early versions were targeted toward nonmedically trained law enforcement officers, but it was apparent that the content could also be made available to the public. These ideas were the genesis of what became known as the Bleeding Control Basic (B-CON) course, which was released to the public in 2014 and forms the foundation of the Stop the Bleed course.

The Stop the Bleed campaign was initiated in 2015 by a federal interagency workgroup convened by the National Security Council staff. The purpose of the campaign is to build national resilience by better preparing the public to save lives by raising awareness of basic actions to stop life-threatening bleeding following everyday emergencies and man-made and natural disasters. The ACS publicly introduced bleeding control training courses in October 2016, and since then thousands of medical professionals have trained to become course instructors. Those instructors are focused on training people in all walks of life to become immediate responders through the Stop the Bleed course [14].

Active shooter and other mass casualty events — Following the Sandy Hook Elementary School shootings in the United States in 2012, a concerned local trauma surgeon, Lenworth Jacobs, who was the Chair of the Connecticut State Committee on Trauma and an ACS Regent, convened a panel of national experts to evaluate the response to such emergencies.

The group met several times and developed recommendations on how to improve survival for people with severe bleeding. Because two of these early meetings were held in Hartford, their recommendations became known as the Hartford Consensus.

The Hartford Consensus recommends an integrated active shooter response that should include the critical actions contained in the acronym THREAT:

●Threat suppression

●Hemorrhage control

●Rapid Extraction to safety

●Assessment by medical providers

●Transport to definitive care

This approach emphasizes the importance of rapid hemorrhage control and treatment focused on the most acute patients using triage principles.

Triage and hospital transfer — Hemorrhage control in compressible areas should ideally be performed prior to patient arrival at a hospital. After hemorrhage control is achieved, there is often a vascular injury that requires timely definitive operative intervention (eg, arterial repair or bypass, venous repair/ligation). For these reasons, triage guidelines have been developed to ensure the rapid transfer of patients to high-level trauma centers with 24/7 operative capability [15]. In the latest revision of the US National Guidelines for the Field Triage of Injured Patients, "active bleeding requiring a tourniquet or wound packing with continuous pressure" was added to the criteria requiring transport to the highest level of trauma center available in the area.

RAPID ASSESSMENT — Hemorrhage that is not adequately controlled can quickly lead to hemorrhagic shock. Exsanguination and death can occur within three to five minutes with bleeding from a major arterial source such as the common femoral artery or carotid artery. Rapid assessment is essential and identifies the site of bleeding, whether the site is compressible, and a general estimate of blood volume loss. In trauma patients, there may be multiple sites of bleeding, which are managed concurrently. More severe sites of bleeding are prioritized over less severe sites.

Compressible versus noncompressible sites — The ability to control hemorrhage depends on the anatomic site, which are generally regarded as compressible or noncompressible.

●Compressible bleeding can be stopped with a high level of external pressure. These sites include the extremities and junctional areas such as the groins and axilla.

●Noncompressible sites include those that require operative intervention to control such as sites within the abdomen or chest. As an example, bleeding from an aortic injury is considered noncompressible.

Specific sites

Head and neck — Scalp wounds can have significant bleeding but should be compressible and controlled with direct pressure or rapid wound closure.

Zone 3 in the neck (table 1 and figure 1) is incompressible due to overlying bony structures. Zone 1 and 2 neck injuries may be compressible; however, the amount of pressure needed to control severe bleeding is limited by the need to avoid collapsing the airway. Thus, controlling the airway with endotracheal intubation is critical.

Extremity — External bleeding from an extremity, and particularly bleeding from the junctional segment of the extremity vasculature (eg, common femoral artery, axillary artery), is life-threatening and should be controlled as soon as possible [16]. Hemorrhage from the extremity distal to the axilla or groin is generally compressible and can usually be controlled with direct pressure. Hemorrhage originating in the axilla or groin, while considered compressible, can be difficult to control with pressure alone.

Torso — Hemorrhage from penetrating trauma to the torso may be from the chest or abdominal wall but is more likely from an internal source. Chest or abdominal wall hemorrhage may be compressible and respond to direct pressure. However, distinguishing internal hemorrhage from chest/abdominal wall hemorrhage can be very difficult. Thus, any patient with a wound on the torso should be considered to have underlying internal hemorrhage until proven otherwise and must be evaluated promptly at a trauma center. Hemodynamically unstable patients with significant torso hemorrhage require surgical exploration.

MANAGEMENT OF HEMORRHAGE — Management of external hemorrhage includes resuscitation and direct pressure, wound packing, or the use of extremity tourniquets.

Compressible hemorrhage

Direct pressure — Direct pressure remains the initial treatment and effectively controls bleeding in most patients with compressible bleeding. (See 'Compressible versus noncompressible sites' above.)

For direct pressure to be effective, the source of the bleeding must be determined. Exposing the wound by removing overlying clothing is the key to determining the best place for direct pressure. Direct pressure at the source of bleeding is achieved by pushing hard against source of bleeding or into the wound and driving the pressure down into an underlying hard surface without letting up to check the wound [17].

Bloody bandages should be left in place and direct pressure applied over the wound. Exchanging the bandages simply removes direct pressure and is not recommended. Moreover, reinforcing saturated bandages only increases the surface area and decreases true pressure on the bleeding vessel.

Prolonged application of direct pressure is only practical if there are enough resources available to continue the direct pressure until the bleeding stops or definitive control is obtained. In some situations (transport, tactical environment, multiple patients), the resources may not be available to sustain direct pressure and other methods of hemorrhage control should be used.

Wound packing — Wound packing fills any area of dead space and increases direct pressure on the vessels deep within the wound [18].

To pack a traumatic wound, a clean cloth, gauze, or hemostatic-impregnated dressing is pressed deeply and firmly into the wound. While maintaining direct pressure, packing should be added until the wound is completely filled. Once packed, the wound should be covered with a dressing and pressure applied using two hands and maintained until hemostasis is achieved [18].

Options for commercially available hemostatic-impregnated dressings include factor concentrators, mucoadhesives, and procoagulants. These dressing can be used to apply direct pressure as well as pack a wound. At least three minutes of direct pressure should be applied after these dressings are placed [19,20]. Note that some dressings may have a radiopaque marker that can cause scatter on computed tomographic (CT) imaging. (See "Overview of topical hemostatic agents and tissue adhesives", section on 'External agents'.)

Extremity tourniquets — In the extremities, when direct pressure/hemostatic packing is unsuccessful, the judicious application of an extremity tourniquet as a temporary adjunct to control compressible hemorrhage (arterial bleeding) is endorsed by Advanced Trauma Life Support (ATLS) and trauma society guidelines [8,10,21]. When used properly, tourniquets completely and consistently occlude arterial blood flow. (See 'Extremity tourniquet techniques' below.)

Types

●Combat tourniquets – A variety of tourniquets have been developed to manage combat-related extremity hemorrhage with a low risk of ischemia and neurologic complications [4,22]. In the prehospital or military setting, the most used tourniquets are the windless style Combat Application Tourniquet (CAT) and Special Forces Tactical Tourniquet. These can be applied rapidly with one hand, if necessary. These, along with the Emergency and Medical Tourniquet, meet the effectiveness standard of the United States military and occlude distal flow in >80 percent of subjects [4,22].

●Pneumatic tourniquets – Pneumatic tourniquets are commonly used to reduce bleeding during elective upper extremity and lower extremity surgery. They can also be used in the emergency department setting to control extremity hemorrhage to improve patient survival [4,23].

●Junctional tourniquets – Junctional tourniquets are external compression devices that occlude blood flow from the aorta, axillary artery, or iliac artery to prevent hemorrhage [24-26]. While junctional tourniquets are approved by the US Food and Drug Administration and Department of Defense, junctional tourniquets are less reliable and less likely to be available. There are also inadequate clinical experience and data in civilian trauma to routinely recommend their use [27]. Under some circumstances such as when the patient requires transportation, an experienced clinician may opt for placing a junctional tourniquet following packing the wound with hemostatic gauze.

Effectiveness — Among trauma patients with life-threatening extremity hemorrhage, survival is increased the earlier a tourniquet can be applied. In the combat setting, mortality was universal when a tourniquet was not applied among those who were candidates for one. The relative effectiveness of tourniquets has been evaluated in human volunteers, with each shown to attenuate the distal arterial pulse in the extremities [28].

The Tactical Combat Casualty Care Committee of the United States military routinely reviews the performance of commercial tourniquets [29]. The benefits of tourniquet application are illustrated in the following studies in combat casualty populations:

●In a study that evaluated 165 patients, 67 of whom had a prehospital tourniquet applied, control of bleeding was significantly improved with tourniquet application versus no tourniquet (83.3 versus 60.7 percent), and there were no differences in secondary amputation rates [22].

●A prospective study of 232 combat casualties reported a significantly improved survival rate (77 versus 0 percent) when using a tourniquet (prehospital or emergency department) versus no tourniquet [4]. In this study, no amputations were required due to tourniquet use, but four transient nerve palsies were reported.

●In a retrospective study, 94 percent of the service personnel who had applied a CAT to the upper extremity achieved complete hemorrhage control, and no deaths were reported [30].

Similar results have been demonstrated in civilian patients with both prehospital and in-hospital tourniquet application [31-33]. For upper extremity hemorrhage that is not adequately controlled with direct pressure, retrospective studies have shown that extremity tourniquets reduce bleeding with a low rate of complications [34-36]. In an American Association for the Surgery of Trauma (AAST) multicenter prospective analysis of prehospital tourniquet use for extremity civilian trauma, prehospital tourniquet application was being widely and safely adopted and was associated with decreased incidence of arrival in shock without increasing limb complications [37,38].

For junctional wounds at the axilla or groin, wound packing, ideally with a hemostatic dressing, along with continuous pressure is recommended [16]. There are insufficient data to recommend the available junctional tourniquets on the market.

Noncompressible torso hemorrhage — Noncompressible torso hemorrhage can only be treated effectively with prompt operative or endovascular intervention. It is therefore essential that patients with noncompressible torso hemorrhage are transported to trauma centers with resources available to immediately provide these interventions. The National Guidelines for the Field Triage of Injured Patients are used in the prehospital environment to aid in ensuring proper patient transport decisions [15]. Reducing the severity of bleeding prior to definitive control follows guidelines for damage control and resuscitation. These measures are briefly discussed below and in more detail in the linked topics. (See "Overview of damage control surgery and resuscitation in patients sustaining severe injury".)

Circumferential compression devices are most likely to benefit a patient with severe pelvic fracture. Recognizing the diagnostic limitations in the field, it is often not possible to differentiate a stable from an unstable fracture pattern in the prehospital setting. There is no clinical evidence that pelvic compression worsens displacement of certain fracture patterns, particularly lateral compression fractures or causes injuries to internal structures through fracture fragment motion. A prehospital pelvic circumferential compression device (PCCD) is recommended in suspected pelvic fracture based on a mechanism of severe blunt force trauma or one of the following: pain on examination, hypotension, a compromised exam by altered mental status or distracting injury, or blast/high energy injury with lower extremity amputation. Prolonged use or overtightening of PCCD may cause pressure ulceration [39]. (See "Pelvic trauma: Initial evaluation and management", section on 'Initial stabilization and approach'.)

EXTREMITY TOURNIQUET TECHNIQUES

Tourniquet placement — To effectively place an extremity tourniquet:

●Use a commercial tourniquet, whenever possible. If an improvised tourniquet must be used, care must be taken to ensure that the benefits outweigh the risks; however, improvised tourniquets are generally not recommended and should be converted to a commercial tourniquet as soon as possible [40]. The commercial tourniquet should be placed proximal to the wound before the improvised tourniquet is removed.

●Apply the tourniquet a minimum 2 to 3 inches proximal to the wound but not over a joint. Applying a tourniquet too close to the wound can increase risk for additional tissue damage. Placing a tourniquet "high and tight," which is placing it as proximal on the extremity and as tight as possible on the injured extremity should be limited to circumstances where it is impossible or unsafe to determine the exact source of bleeding.

●Place the tourniquet on bare skin, whenever possible. Fully expose the involved limb(s), removing clothing from the limb(s), and do not cover a tourniquet with bandages or any other material.

●Do not place a tourniquet over the elbow, wrist, knee, or ankle joints. Application over the peroneal nerve (knee or ankle) or ulnar nerve (elbow) may result in nerve damage or paralysis.

●Ensure that all slack is removed before tightening the windlass to avoid bunching and twisting.

●Tighten the tourniquet until bleeding stops and the distal pulse is eliminated. Applying a tourniquet too loosely may reduce bleeding, but if the distal pulse remains, ongoing arterial flow with obstruction to venous return can result in an increase in venous bleeding. The consequences of this include avoidable pain due to venous congestion and potential compartment syndrome. If pulses are present and there is ongoing hemorrhage, it is likely the tourniquet is not controlling the artery. In this case, the tourniquet should be tightened until the distal pulse is eliminated.

●Note the time the tourniquet was applied and record this time, so the information is readily available. Preferably, the time should be recorded on the patient or the tourniquet.

●Do not loosen the tourniquet once applied until the patient is in a definitive care setting.

●To maintain effectiveness of hemorrhage control, reassess the wound and tourniquet following any patient movement (eg, ground to stretcher, stretcher to ambulance) and during transport to ensure continued adequate hemostasis.

●If hemostasis is not obtained, add a second tourniquet 2 to 3 inches above the tourniquet in place. Do not remove the original tourniquet.

●In the hospital setting (eg, emergency department, operating room), pneumatic tourniquets can also be used to control hemorrhage in the extremities distal to the axilla and groin. The distal aspect of the pneumatic cuff should be placed at least 5 cm proximal to the wound, if possible. The inflation pressure of the pneumatic should be less than 250 mmHg. To avoid ischemic complications, the pneumatic should not be inflated continuously for more than two hours [34-36]. The patient should proceed to the operating room for rapid hemorrhage control.

Pitfalls and complications — With proper technique, many complications can be avoided. Pitfalls to avoid include the following [41,42] (see 'Extremity tourniquet techniques' above):

●Delaying or avoiding a tourniquet placement for life-threatening extremity bleeding.

●Applying a tourniquet to control bleeding when other methods such as direct pressure and wound packing would suffice.

●Applying a tourniquet over a joint.

●Applying a tourniquet over clothing.

●Applying a tourniquet too loosely.

●Delaying or avoiding a second tourniquet when arterial bleeding continues.

●Loosening a tourniquet periodically.

●Failing to reassess a tourniquet that may have loosened during transport.

●Removing a tourniquet on a patient in shock and/or ongoing, uncontrolled bleeding.

●Allowing patient pain to interfere with proper hemorrhage control.

Tourniquet conversion — Tourniquet conversion is the deliberate process of exchanging a tourniquet for a pressure dressing. Any patient who has a tourniquet applied for hemorrhage control should be evaluated as quickly as possible by a surgeon capable of providing definitive repair. However, with the widespread education efforts of Stop the Bleed, tourniquets are much more commonly placed. Often, these wounds could have been controlled with direct pressure, but the responder placed a tourniquet. In a large study of prehospital tourniquet placements, only 39 percent of patients in whom a tourniquet was applied had a major vascular injury [37].

With this knowledge, the American College of Surgeons Committee on Trauma (ACS-COT), the National Association of EMS Physicians, and the American College of Emergency Physicians released guidance on the appropriate removal of a tourniquet in a setting where a surgeon may not be immediately available [43].

Per the guideline, tourniquet conversion is only recommended when:

●The patient is not in shock as defined by:

•Systolic blood pressure (SBP) <90 mmHg if age 10 to 64

•SBP <110 mmHg age if age ≥65

●Anticipated transport time to a location where surgical support is immediately available is more than two hours [17].

●Tourniquet has been applied for less than six hours [18-20].

●The wound can be monitored for rebleeding during the entire patient transport.

●Absence of complete or near complete amputation.

Technique for tourniquet conversion — Place a new tourniquet, referred to as "Tourniquet Plus 1," 2 to 4 inches proximal to the wound and keep it loose. If the original commercial or improvised tourniquet is in this same area, place the new loose Tourniquet Plus 1 proximal to the original tourniquet.

●Apply a pressure dressing to the wound. A hemostatic-impregnated dressing may be used if available.

●Loosen/release the windlass rod on the initial commercial or improvised tourniquet.

●Monitor the wound for bleeding.

●If no bleeding occurs, successful conversion to bleeding control without a tourniquet has been accomplished. Resolving arterial spasm causing delayed bleeding during tourniquet conversion is a possible cause of rebleeding, so careful monitoring of the wound once the tourniquet is removed is required. If bleeding recurs despite the pressure dressing, tighten Tourniquet Plus 1.

●If bleeding continues despite tightening Tourniquet Plus 1, tighten the original tourniquet (if commercial), and replace any improvised tourniquet with a commercial tourniquet.

●Continue to reassess any tightened tourniquet(s) for effectiveness [43].

PEDIATRIC CONSIDERATIONS — Pediatric circulating blood volume is approximately 80 mL/kg. A child may lose up to 45 percent of circulating blood volume before exhibiting hypotension. Therefore, hypotension is a late sign of shock. Hypotension in children is determined by age and systolic blood pressure (SBP). For children aged zero to nine, hypotension is defined as SBP <70 mmHg + [age in years x 2]. For children aged 10 and up, hypotension is defined as SBP <90 mmHg. Shock index (SI), which is the ratio of heart rate to SBP, has been demonstrated to be a sensitive marker for shock. As a result, SI >1 (heart rate > SBP) is another marker of hypotension in those age 10 and up and was incorporated into the US National Guidelines for the Field Triage of Injured Patients as a physiologic marker of serious injury [15].

In the pediatric populations, direct pressure at or immediately proximal to the site of injury should always be the initial technique for hemorrhage control [44]. If direct pressure fails to control exsanguinating external hemorrhage from an extremity, a tourniquet should be applied [44]. Except for children less than two years old, the same tourniquet that is used for adults can be used for children. (See 'Types' above.)

The tourniquet should be placed 2 to 3 inches proximal to the bleeding site with enough proximal pressure to impede arterial blood flow [45]. (See 'Extremity tourniquet techniques' above.)

There are published studies in children two to seven years and 6 to 16 years where adult tourniquets were successfully used, although three windlass turns were often needed. If the tourniquet fails to provide occlusion, direct pressure should be used [46-48]. Junctional tourniquets may work on teenagers and larger children but there is limited information to provide guidance. If commercial tourniquets are too large, apply direct pressure on the wound. For large, deep wounds, pack the wound. Hemostatic-impregnated dressings should be applied with at least three minutes of direct pressure [19,20]. Tourniquets should frequently be reevaluated after placement for appropriate positioning and adequate control of bleeding [44].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Extremity compartment syndrome" and "Society guideline links: Severe blunt or penetrating extremity trauma".)

SUMMARY AND RECOMMENDATIONS

●External hemorrhage – Uncontrolled hemorrhage due to trauma remains the leading cause of preventable trauma death. In addition to the role of emergency medical services (EMS) in managing external hemorrhage in the field, focused efforts through the Stop the Bleed Campaign have empowered civilians who witness injuries causing severe external hemorrhage to apply pressure, pack wounds, and even place tourniquets for uncontrolled hemorrhage, when needed. Placement of a tourniquet mandates transport to the highest-level trauma center available in the area. (See 'Prehospital care setting' above.)

●Rapid assessment – A stepwise approach to managing hemorrhage involves assessing the location, type, and severity of bleeding and implementing various techniques for hemorrhage control. The ability to control external hemorrhage depends on the anatomic site, which are generally regarded as compressible or noncompressible. (See 'Compressible versus noncompressible sites' above.)

•Compressible bleeding can be stopped with a high level of external pressure.

•Noncompressible sites include those that require operative intervention to control such as sites within the abdomen or chest.

●Management of compressible hemorrhage

•Initial steps – Compressible hemorrhage is managed initially with direct pressure. If bleeding is not adequately controlled, the next step is to pack the wound and to continue to apply pressure. (See 'Direct pressure' above and 'Wound packing' above.)

•If hemorrhage continues – Subsequent management depends on the location of the wound:

-Distal to the axilla or groin – For uncontrolled extremity hemorrhage distal the axilla or groin , placement of a tourniquet is the next appropriate step. Military and civilian experience with prehospital and emergency department tourniquet application has shown that tourniquets save lives with a low rate of complications. (See 'Extremity tourniquets' above.)

-From the axilla or groin – For uncontrolled hemorrhage from the axilla or groin, we suggest packing, ideally with hemostatic gauze, and continued pressure, rather than attempting to use a junctional tourniquet (Grade 2C). Junctional tourniquets are less reliable and less likely to be available. Under some circumstances such as when the patient requires transportation, an experienced clinician may opt for placing an available junctional tourniquet following packing the wound with hemostatic gauze. (See 'Extremity tourniquets' above.)

-From the neck – For uncontrolled hemorrhage from the compressible region of the neck (zone 1, zone 2), packing, ideally with hemostatic gauze, and pressure are continued. The patient should be intubated to protect the airway and allow maximal pressure to be applied to the wound.

●Management of noncompressible hemorrhage – External hemorrhage from penetrating trauma to the torso may be from the chest or abdominal wall but is more likely from an internal source. Distinguishing between internal hemorrhage or chest/abdominal wall hemorrhage can be very difficult. Thus, any patient with a wound on the torso should be considered to have underlying internal hemorrhage until proven otherwise and must be evaluated promptly at a trauma center. (See 'Noncompressible torso hemorrhage' above.)

●Pediatric considerations – In children, hypotension is a late sign of shock. The principles of hemorrhage control are similar. Direct pressure should always be the initial technique for hemorrhage control, but if this fails to control exsanguinating external hemorrhage from an extremity, a tourniquet should be applied. The same tourniquet that is used for adults can be used for children, except for children less than two years old. (See 'Pediatric considerations' above.)