Pop Quiz #2 – Answer
A 22yo male was “minding his own business” when he what shot multiple times with a 9 mm handgun in right thigh and left shoulder. Upon arrival in trauma bay #1 you perform your initial assessment and begin resuscitation efforts. Based on your initial assessment, you suspect that this upstanding member of the community is suffering from hemorrhagic shock. What is the most likely initial indication that a patient may have hemorrhagic shock?
A. Change in mental status
B. Depressed systolic blood pressure
C. Distended neck veins
D. Muffled heart sounds
F. Thready pulses
Discussion: The three most likely answers when I first thought about this myself were tachycardia, thready pulses (which two people suggested as being correct) and low blood pressure. However, it turns out the earliest manifestations of shock include tachycardia and cutaneous vasoconstriction. Reliance solely on systolic blood pressure (or thready pulses for that matter) may cause a delay in recognition of the shock state. The compensatory mechanisms of the human body are quite impressive and a normal, young, healthy individual, who always minds his own business but just happens to get shot twice, can maintain normal pressure until up to 30% of his blood volume is lost. Pretty impressive.
However, when considering tachycardia as an early sign of shock, the patients backstory must be considered. While elderly patients may be more prone to be up in everyone’s business (Recent example “What does this asshole think he’s doing turning around in my driveway?”), they may not exhibit tachycardia because of their limited cardiac response to catecholamines or they may be on Beta blockers, or they may even be paced. In these patients, look for a narrowed pulse pressure to suggest significant blood loss and involvement of compensatory mechanisms.
Bottom Line: Any injured patient who has tachycardia is considered to be in shock until proven otherwise.
Source: Advanced Trauma Life Support for Doctors (ATLS). Eighth Edition. American College of Surgeons Committee on Trauma.