Advanced Bleeding and Shock Control

At the paramedic level, shock management becomes more complicated as the provider must be able to identify and treat varying types of shock beyond that caused by loss of blood volume.

This section will review the details surrounding the advanced EMS treatment of bleeding, the types of shock patients experience, how those types of shock are related to anatomy/physiology, the complications of shock, and how it is managed.

Beyond these advanced topics, the paramedic level of treatment for shock and bleeding has the same basics: scene safety, aggressive assessment, control of the ABCs, rapid transport to appropriate care, and avoiding the delay of definitive treatment.

 

Paramedic: Detailed Focus on ABCs

AIRWAY: Patients in shock due to blood loss resulting from trauma may require advanced interventions due to co-dominant airway compromise from trauma. Severe internal blood loss into the GI tract, spaces of the neck, or lungs may cause blood to compromise the airway directly. Most commonly, altered mental status from blood loss can cause patients to lose control of their airway. Evaluate carefully for altered mental status, trauma to the airway, and signs of obstruction (choking, stridor, swelling).

BREATHING: If a problem with breathing exists, it is vital to keep oxygen saturation as high as possible to maximize oxygen delivery in the shock setting. An oxygen saturation above 91% should be maintained at all times. Saturations below 91% can rapidly and dramatically cut the amount of oxygen available to the tissues. Some of the most common causes of low oxygenation in shock are decreased level of consciousness, airway obstruction, massive blood loss, and heart or chest wall trauma.

Insufficient ventilation or respiration will accelerate a patient's deterioration and rapidly cause the progression of shock if it exists. The presence of a tension pneumothorax or large-volume hemothorax could directly cause shock.

CIRCULATION: Shock is all about circulation. Even when a patient is in obvious shock, don't forget to look for other secondary circulation issues. Crush injuries, damaged arteries, and tourniquets can all further disrupt blood flow to smaller areas of the body, even when patients are in an overall state of shock. If a local injury is present, that limb or general area should be assessed for distal pulse quality, sensation, and local skin tone and temperature. 

 

Types of Shock

Shock is caused by insufficient blood flow (blood pressure.) The equation for blood pressure is as follows.

PRESSURE = CARDIAC OUTPUT X SYSTEMIC VASCULAR RESISTANCE

Cardiac output (CO) is the amount of blood moved by the heart over the course of a minute. Systemic vascular resistance (SVR) is the degree to which the blood vessels are constricted. Altering SVR is the primary way that the body regulates blood pressure. Dramatic reductions in either CO or SVR will lead to shock.

Complete exposure and thorough field assessments are often needed to establish the cause. This is vital as specific types of shock often require transport to specific specialty treatment centers. The most common types of shock involve the following areas:

HYPOVOLEMIC: Shock due to the loss of preload (a component that determines cardiac output). Low blood volume in the right atrium and ventricle lowers the heart's strength; this effect, combined with low circulating blood volume, leads to shock. Hypovolemic shock is often caused by burns, severe dehydration, and blood loss (hemorrhage).

NEUROVASCULAR: Shock due to decreased systemic vascular resistance. Inappropriate dilation of blood vessels due to chemical or neurologic signals results in a massive drop in blood pressure despite adequate cardiac output, leading to low blood flow to vital tissues. Neurovascular shock is often caused by allergic reactions (anaphylaxis), infections (Sepsis), and injury to the brain or spinal cord.

CARDIAC: Shock due to decreased cardiac contractility (a component that determines cardiac output). Damage to the cardiac muscle or nerve cells can result in an inability of the heart to contract properly, dramatically lowering the cardiac output and causing tissue ischemia. Cardiac shock is often caused by myocardial infarction, congestive heart failure, tamponade, tension pneumothorax, and blunt cardiac injury.

RESPIRATORY: Shock due to a lack of oxygen entering the body. Any disruption to the airway or lungs can result in tissue hypoxia even if the cardiac output and systemic vascular resistance are normal. Respiratory shock is often caused by airway obstruction, pulmonary embolism, and chest wall injury.

 

Compensation for Shock

When any of the above systems begin to fail, the body will attempt to maintain homeostasis. The two classic compensatory mechanisms in shock are as follows:

Vasoconstriction - clamping down of the vascular system to increase blood pressure. This increases systemic vascular resistance.

Tachycardia - attempts to increase the volume of blood delivered per minute to the body by increasing how often the heart beats. This increases cardiac output.

 

Management of Shock

This section will break down shock by the interventions available to the EMS provider for its treatment. The most important differentiator is the responsiveness of shock to fluids. The first two are treated with fluid, and the second two cannot be treated with fluids, and giving fluids will kill the patient. 

HYPOVOLEMIC: Patients with low volume leading to shock require... more volume. This is the only treatment for low volume. Loss of blood volume leads to low preload in the heart, lowering cardiac output. They need this preload restored (through fluids) to recover. This is why hypovolemic shock is called "fluid responsive." Hypovolemic shock patients are generally severely dehydrated or losing large amounts of blood (hemorrhage). 

• Administer IV fluid (30 ml/kg in 250-500 ml boluses) through two large bore (16+ gauge) IV's.
  • Avoid giving more than 30ml/kg in hemorrhage to avoid washing out clotting factors. Your goal blood pressure should likewise be 70 to 90mmhg to prevent this same washout, this is known as "permissive hypotension."
  • If permitted in your jurisdiction, consider administration of packed red blood cells or plasma if the 30 ml/kg limit is reached.
• Support oxygenation via a non-rebreather mask.
• Consider transport to trauma centers in case of hemorrhage.

NEUROVASCULAR: Neurovascular shock is related to reductions in systemic vascular resistance due to an inability of the blood vessels to constrict appropriately, dramatically lowering the blood pressure. In Neurogenic shock, this occurs because the nerves that lead to the blood vessels are damaged, such as in spinal cord injury. In vascular shock, this is due to chemical imbalances in the body preventing the muscle cells in the vessels from contracting. Septic shock and anaphylaxis are the classic vascular shocks. This is the second type of fluid-responsive shock.

• Administer IV fluid (30 ml/kg in 250-500 ml boluses) through two large-bore (16+ gauge) IVs.
  • Consider administering "pressors," which are medications that directly cause the blood vessels to constrict. The use of these medications is limited based on the jurisdiction in which you practice.
• Support oxygenation via a non-rebreather mask.
• If your ambulance carries a MAST suit (military anti-shock trousers), its placement can be helpful in neurogenic shock secondary to spinal trauma.
• In anaphylaxis, removing the allergen, if possible, and administering epinephrine is vital.

CARDIAC: Cardiac shock is related to the heart losing its ability to squeeze (contractility). There are countless causes of low contractility. But the important ones for EMS are myocardial infarction (MI) heart failure, cardiac tamponade, and tension pneumothorax. 

MI directly stops the heart from squeezing by cutting off the oxygen supply to the cells. Heart failure is when damaged cells can no longer squeeze hard enough to get blood to the rest of the body. Cardiac tamponade and tension pneumothorax prevent the right atrium from filling up by putting pressure on the outer walls of the heart, lowering contractility and eventually stopping the heart. 

• Cardiac shock is not fluid-responsive. Giving fluid will quickly kill these patients.
• The treatment for cardiac shock is rapid transport. There are many causes of cardiac shock that cannot be stabilized in the field.
• Support oxygenation via a non-rebreather mask.
• Decompress any existing tension pneumothorax.

RESPIRATORY: Respiratory shock is caused by a lack of oxygenation. This is the only form of shock not usually caused by vascular issues. As such, it does not usually involve problems with cardiac contractility or vascular resistance. Respiratory shock is caused by airway obstruction, low oxygen atmospheres, fluid-filled lungs, and chronic respiratory diseases that have acutely decompensated.

• Respiratory shock is not fluid-responsive. Giving fluid generally results in more fluid filling the lungs, worsening the hypoxemia.
• Giving oxygen is the only effective method of treating respiratory shock.
• Artificial ventilation and CPAP may support patients with fluid-filled alveoli or chronic respiratory diseases.
• Respiratory shock is often seen in conjunction with cardiac shock secondary to MI or heart failure. 

DON'T FORGET TEMPERATURE!

The final consideration in the management of shock is temperature. Patients should always be kept warm to reduce the loss of heat from the body due to bleeding/vasodilation and to limit the amount of oxygen expended by shivering.

 

Details of IV Fluid Administration

When administering IV fluids, there are several considerations that can be made to optimize your patient's outcomes.

There are two types of fluid: crystalloids and colloids. Within 30 minutes, 20% of crystalloid fluids remain in the intravascular space while the other 80% moves to the interstitial space. This is because they are ISOTONIC with plasma (with rare exceptions). On the other hand, colloids are retained in the intravascular space for 2 to 36 hours, leading to prolonged intravascular expansion--because they are HYPERTONIC to plasma.

Common crystalloids are normal saline (NS) and Lactated Ringers (LR). Colloids are--alternatively and most importantly--considered blood products.

Research shows that giving crystalloids only is associated with "the worst survival," per a randomized control trial published in 2022. In the prehospital setting, crystalloids should be given initially until blood products can be obtained, after which blood products (colloids) are indicated to maintain coagulation and oxygenation. More and more ground critical care, air medical, and even some ALS services are now carrying blood products to be administered as FIRST LINE treatment.

A secondary analysis of a randomized control trial: https://pubmed.ncbi.nlm.nih.gov/30998533/

CRYSTALLOID FLUIDS: Crystalloid fluids commonly used in healthcare include lactated ringers (LR), 0.9% normal saline (NS), and 5% Dextrose in water (D5W).

• Lactated Ringers: Secondary to blood products, this is the preferred choice for all patients in all forms of fluid-responsive shock (Neurovascular and Hypovolemic). 

• 0.9% Normal Saline: NS is a classic choice for fluid administration because its 0.9% sodium chloride-in-water formulation is specifically made to be isotonic (matching the tonicity in tissues). However, recent studies have shown that lactated ringers has much better patient outcomes, especially in septic and trauma patients, because normal saline propagates acidosis. Because of this, normal saline use has become less common. It is still safe to use in limited volumes if no other options are available. Most agencies have transitioned to utilizing lactated ringers exclusively for septic shock and trauma patients if blood products are not available/utilized at that agency. Your local protocols may mandate NS use in certain conditions.

• 5% Dextrose: Sugar water is used in patients with concerns about low glucose. It is often used in unresponsive diabetics, alcoholics, or those with hypoglycemia. Always administer this drug in conjunction with thiamine unless your local protocols state otherwise. 

COLLOID FLUIDS: The other family of IV fluids known as "colloids" have a high oncotic pressure, meaning they draw fluid into the vasculature from the cells and interstitial space. There are many fancy colloids used in heart and liver failure, but the important ones for EMS are the "blood products."

If a patient has received the maximum IV fluid dose of 30 ml/kg with little to no improvement, blood products are typically indicated for administration by paramedics, depending upon the practice environment. 

• Whole Blood: Using whole blood in the prehospital setting, which is happening now with some EMS and HEMS agencies, offers the advantage of rapid volume replacement and improved oxygen-carrying capacity. This makes it a valuable resource for managing critically injured patients, especially in scenarios where timely access to blood products can be challenging. This approach can help stabilize patients and enhance their chances of survival during critical emergencies. 

• Packed RBCs: Used to restore oxygen-carrying capacity, usually indicated if patients are tachycardic, tachypneic, or in distress despite optimal blood pressure and O2 saturation.

• Plasma: Used to restore clotting factors lost in bleeding, indicated in patients who have received the maximum dose of 20 ml/kg IV crystalloid in a 24-hour period. Patients "oozing" blood from IV sites or mucous membranes commonly require plasma infusion.

• Cryo* (cryoprecipitate): Concentrated clotting factors derived from plasma. This product is rarely carried in BLS or ALS ambulances. Some Medivac providers may have this product available for patients severely bleeding with a suspected history of a coagulation disorder (Hemophilia and Von Willebrand).

 

Complications of shock

The two categories of shock complications are progression and residual effects. Progression involves further decompensation during the initial episode of shock, while residual effects are the health concerns that remain if the patient recovers from the acute episode.

PROGRESSION: Worsening shock places patients at high risk for heart attack, stroke, acute respiratory distress syndrome (ARDS), coma, and death. These complications are directly attributable to the reduced perfusion that results from acute shock.

RESIDUAL EFFECTS: Reduced perfusion, even for a short term, can have chronic or sub-acute effects on health. The kidneys and brain are the organs that are most reliant on strong blood flow, making their injury common. The lungs are sensitive to some of the hormones and cytokines released during shock, potentially leading to acute respiratory distress syndrome (ARDS).

Some of the chronic effects relating to the cause of shock are as follows: keep these possibilities in mind if a patient tells you they have been recently hospitalized for any condition that can cause shock.

• Decreases in cardiac output in patients with heart failure or previous myocardial infarction.
• Progression of pre-existing chronic obstructive pulmonary disease (COPD).
• Infections throughout the body in patients with septic shock.