Episode 3 – The Lethal Triad

Welcome back!

This week we talk about one of my favorite topics…shock. Specifically we’re going to discuss the lethal triad of shock. Sounds like a Chinese organized crime syndicate, right? Well, it might be but today we’re applying the terminology to the condition that develops after major trauma. Understanding this process will position you to prioritize and manage the treatment of your trauma patients more effectively.

This triad is the spiral of death, the symphony of destruction in your patients. Recognizing that every patient who suffers major trauma is likely to be suffering from the effects of the lethal triad, before you ever get to them, is critical. Rapid assessment, rapid intervention, and rapid transport are the keys.



The Triad:


  • pH of 7.35 – 7.45 is normal. Below 7.35 is considered acidosis
  • Poor tissue perfusion is the cause; anaerobic metabolism = lactic acidosis
  • Normal saline can worsen acidosis. NaCL 0.9% pH = 5.5
  • Hypoventilation secondary to traumatic injury will worsen acidosis due to onset of respiratory acidosis
  • Profound acidosis will lead to worsening of coagulopathy
  • Intervention is targeting perfusion support


  • Normal body temp = 35.6–37.8°C. Hypothermia = <35°C
  • Assume your major trauma patient is hypothermic prior to your arrival
  • Core temp <32°C = 100% mortality
  • Not seasonal or environmental dependent. Traumatic hypothermia can happen in any environment.
  • Room temp IV fluids worsen hypothermia
  • Hypothermic coagulopathy is the onset of clotting derangement due to low body temp.
  • Treatment involves getting patient out of wet clothing and covered as soon as possible. Warm IV fluid admin. Passive warming techniques. If your not sweating upon arrival at the hospital, your patient is too cold.


  • Derangement in the normal physiology of the blood clotting process
  • Reduced clotting mean increased bleeding
  • Worsened by acidosis and hypothermia
  • Dilutional coagulopathy results from resuscitation with fluid or PRBCs that do not contain clotting factors.
  • Patients on anti-coag therapy at risk for coagulopathic complications
  • Critically ill trauma patients may develop disseminated intravascular coagulation (DIC). DIC = uncontrolled activation of the clotting cascade out of proportion to the injury. This abnormality of the coagulation system consumes the body’s remaining clotting factors worsening bleeding.
  • Prehospital treatment is focused on treating perfusion deficits and supporting hypothermia and acidosis prevention.


Treatment Points:

  • Bleeding control is paramount. Uncontrolled internal hemorrhage requires rapid transport.
  • Assume your patient is hypothermic. Initiate active/passive rewarming techniques rapidly.
  • Attempt to maintain MAP = 65
  • Limit normal saline admin. Provide limited warm fluid resuscitation if able.
  • High flow oxygen
  • Airway management and hypoventilation prevention. Onset of respiratory acidosis will quickly kill these patients.




Thanks for joining us again. Hope you enjoyed it! Please leave some feedback in the comments. Ask any questions you might have. Feel free to email us with any thoughts. We’ll be back with another episode next week! – Derrick


PS –

If you liked this post, check out our previous post on the Killer Five: