Hypotensive Resuscitation for Hemorrhagic Shock after Trauma

How Much Intravenous Fluid should be Administered to Trauma Patients?

When patients suffer severe trauma (injury), they may have internal or external bleeding.  One consequence of bleeding is that there is less blood available to carry oxygen and nutrients to the tissues.  With severe blood loss, blood pressure may decrease.  This situation is referred to as shock.  Unless bleeding is controlled and shock is reversed, a patient may suffer damage to vital organs or die.

The traditional treatment of trauma patients is to give clear intravenous fluids (“crystalloid”), such as saline (salt water) to restore effective circulating volume and blood pressure.  This approach to resuscitation is endorsed by the American College of Surgeons Committee on Trauma and the Advanced Trauma Life Support course. Current guidelines suggest resuscitating all trauma patients with signs of shock with two or more liters of crystalloid in order to restore a normal blood pressure.

Over the last two decades, this practice has been challenged by clinical and basic research. Both animal and human studies indicate that administration of large amounts of intravenous crystalloids prior to controlling bleeding is associated with cardiac dysfunction, abdominal compartment syndrome, harmful inflammation, acute respiratory distress syndrome, multiple organ dysfunction syndrome and increased death.   These detrimental effects of intravenous crystalloids may result from dilution of the blood that remains, increased rates of bleeding from uncontrolled injuries, dislodgement of blood clots, acidosis, and dilution of the factors that allow new blood clot formation.

Both animal and human studies suggest that a better approach might be to tolerate a low blood pressure in the injured patient with shock and to minimize the amounts of clear fluids administered until after internal and external bleeding has been controlled surgically.

Three randomized clinical trials compared early aggressive fluid resuscitation with delayed resuscitation or hypotensive resuscitation.   

1. Bickell et al. compared immediate fluid resuscitation in the ambulance to delayed fluid resuscitation that started after the patient reached the operating room in 598 patients with injuries to the chest or abdomen.  Patients in the immediate fluid group received an average of 870 ml in the ambulance versus 92 ml in the delayed group.  70% of the patients with immediate fluid resuscitation died, but only 62% of patients in the delayed group died.  There was a trend toward more complications in the immediate resuscitation group and their hospital stay was longer.

2. Turner et al. compared immediate fluid resuscitation in the ambulance to delayed resuscitation after hospital arrival in 1309 trauma patients in the United Kingdom.   In this study, compliance with the protocol was poor. Only 31% of patients assigned to immediate fluid resuscitation were given fluids in the ambulance, and 20% of patients who were assigned to no field fluids received fluids in violation of the protocol. There were no differences in morbidity or mortality within 6 months between the two protocol groups.

3. Dutton et al. compared two protocols in the hospital for administering intravenous fluids and blood to blunt and penetrating trauma patients presenting with a low blood pressure (systolic pressure less than 90 mmHg).  In one group, fluids were given to target a blood pressure endpoint of 100 mmHg (liberal fluids).  In the other group, fluids were given to maintain a blood pressure of 70 mmHg (restricted fluids).   Patient survival was 92.7% in both groups.

Why is it important that this research be conducted? 

The laboratory data and the existing clinical studies leave it unclear whether patients should receive a lot of intravenous fluids while being transported to the operating room, or if these fluids are detrimental.  Current Guidelines are based largely on data from the 1970’s, and better information is required to provide the best treatment for trauma patients.

This study will compare two strategies for administering intravenous crystalloids in trauma patients: Standard Resuscitation and Hypotensive Resuscitation.  Patients, who are rescued by an ambulance from a serious injury, have low blood pressure (systolic blood pressure < 90 mmHg) and who are being transported to a trauma center will be eligible to participate.    This study will not include patients with serious head injuries, known pregnancy, burns, drowning or asphyxiation, because those groups have different considerations with regard to fluid administration.  This study will conducted according to the rules for Exception from Informed Consent

Group 1: Standard Resuscitation

The Standard Resuscitation group will be treated according to the Prehospital Trauma Life Support and Advanced Trauma Life Support guidelines which focus on airway, breathing and circulation and which recommend early aggressive fluid resuscitation.  Paramedics will establish an intravenous line (IV) and will connect the IV to a 1000 ml bag of normal saline (salt water). Fluid will be given as rapidly as possible. Additional 1000 ml bags of IV fluid will be administered as needed, and IV fluid will be stopped when the systolic blood pressure exceeds 110 mmHg.  This fluid resuscitation protocol will continue either until 2 hours after hospital arrival or until control of bleeding by surgery or angiography.

  Group 2: Hypotensive Resuscitation

In the Hypotensive Resuscitation group, paramedics will start an IV and will connect the IV to a 250 ml bag of normal saline. Paramedics will then monitor the patient’s radial pulse and blood pressure. If the radial pulse becomes too faint to feel (or the systolic blood pressure is <70 mmHg), the treating team will administer a 250 ml bag of normal saline (salt water).  After each 250 ml bag, the pulse will be checked again, and additional bags of fluid repeated until the radial pulse is palpable (or the systolic blood pressure is >70 mmHg).

After paramedics recognize an eligible patient, they will open a “resuscitation kit” that will have supplies to administer intravenous fluids according to one of the two protocols.  There will only be one kit on each ambulance, and the contents of this kit will be randomly assigned in advance.  Paramedics will not know which protocol is in each kit until the kit is opened. 

After a patient is treated according to these protocols, investigators will review medical records to determine how much fluid was actually administered and how well the patient recovered from the injury.

If you want to comment on this study, or to find out more, please contact Acute Care Research.