eMedicine Specialties > Emergency Medicine > Trauma & Orthopedics

Shock, Hemorrhagic

Author: William P Bozeman, MD, Associate Professor, Associate Director of Research, Department of Emergency Medicine, Wake Forest University School of Medicine
Contributor Information and Disclosures

Updated: Sep 18, 2008

Introduction

Background

Shock is a state of inadequate perfusion, which does not sustain the physiologic needs of organ tissues. Many conditions, including blood loss but also including nonhemorrhagic states such as dehydration, sepsis, impaired autoregulation, obstruction, decreased myocardial function, and loss of autonomic tone, may produce shock or shocklike states.

Pathophysiology

In hemorrhagic shock, blood loss exceeds the body's ability to compensate and provide adequate tissue perfusion and oxygenation. This frequently is due to trauma, but it may be caused by spontaneous hemorrhage (eg, GI bleeding, childbirth), surgery, and other causes.

Most frequently, clinical hemorrhagic shock is caused by an acute bleeding episode with a discrete precipitating event. Less commonly, hemorrhagic shock may be seen in chronic conditions with subacute blood loss.

Physiologic compensation mechanisms for hemorrhage include initial peripheral and mesenteric vasoconstriction to shunt blood to the central circulation. This is then augmented by a progressive tachycardia. Invasive monitoring may reveal an increased cardiac index, increased oxygen delivery (ie, DO₂), and increased oxygen consumption (ie, VO₂) by tissues. Lactate levels, acid-base status, and other markers also may provide useful indicators of physiologic status. Age, medications, and comorbid factors all may affect a patient's response to hemorrhagic shock.

Failure of compensatory mechanisms in hemorrhagic shock can lead to death. Without intervention, a classic trimodal distribution of deaths is seen in severe hemorrhagic shock. An initial peak of mortality occurs within minutes of hemorrhage due to immediate exsanguination. Another peak occurs after 1 to several hours due to progressive decompensation. A third peak occurs days to weeks later due to sepsis and organ failure.

Frequency

United States

Accidental injuries remain the leading cause of death in individuals aged 1-44 years.¹ Hemorrhagic shock is a leading cause of death among trauma patients.²

Clinical

History

History taking should address the following:

• Specific details of the mechanism of trauma or other cause of hemorrhage are essential.
• Inquire about a history of bleeding disorders and surgery.
• Prehospital interventions, especially the administration of fluids, and changes in vital signs should be determined. Emergency medical technicians or paramedics should share this information.

Physical

Findings at physical examination may include the following:

• Head, ears, eyes, nose, and throat
  • Sources of hemorrhage usually are apparent.
  • The blood supply of the scalp is rich and can produce significant hemorrhage.
  • Intracranial hemorrhage usually is insufficient to produce shock, except possibly in very young individuals.
• Chest
  • Hemorrhage into the thoracic cavities (pleural, mediastinal, pericardial) may be discerned at physical examination. Ancillary studies often are required for confirmation.
  • Signs of hemothorax may include respiratory distress, decreased breath sounds, and dullness to percussion.
  • Tension hemothorax, or hemothorax with cardiac and contralateral lung compression, produces jugular venous distention and hemodynamic and respiratory decompensation.
  • With pericardial tamponade, the classic triad of muffled heart sounds, jugular venous distention, and hypotension often is present, but these signs may be difficult to appreciate in the setting of an acute resuscitation.
• Abdomen
  • Injuries to the liver or spleen are common causes of hemorrhagic shock. Spontaneous rupture of abdominal aortic aneurysm (AAA) may also cause severe intra-abdominal hemorrhage and shock.
  • Blood irritates the peritoneal cavity; diffuse tenderness and peritonitis are common when blood is present. However, the patient with altered mental status or multiple concomitant injuries may not have the classic signs and symptoms at physical examination.
  • Progressive abdominal distention in hemorrhagic shock is highly suggestive of intra-abdominal hemorrhage.
• Pelvis
  • Fractures can produce massive bleeding. Retroperitoneal bleeding must be suspected.
  • Flank ecchymosis may indicate retroperitoneal hemorrhage.
• Extremities
  • Hemorrhage from extremity injuries may be apparent, or tissues may obscure significant bleeding.
  • Femoral fractures may produce significant blood loss.
• Nervous system
  • Agitation and combativeness may be seen in the initial stages of hemorrhagic shock.
  • These signs are followed by a progressive decline in level of consciousness due to cerebral hypoperfusion or concomitant head injury.

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