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Likelihood Ratio (LR) in Emergency Medicine


Is it always necessary to perform an arterial blood gas after a blunt trauma?

   Clinical Scenario

A 53 year old man is involved in a motor vehicle crash. He refers a moderate thorax and abdominal pain. No head injury, the helmet is not broken, the patient remembers the accident. Systolic blood pression is 120/80 mmHg, respiratory rate is 24, saturation is 100%, he has abrasions over the torso and right thorax and flank, no wounds. The eFAST shows a normal pleural sliding, and no signs of intraperitoneal blood.
 The institutional blunt trauma protocol requires an arterial blood gas (ABG) and serum lactate (SL), than is obtained a CT of the chest abdomen and pelvis. 
After 15 minutes, the patient returns to the ED, TC is negative, the patient feels better, the nurse says that the ABG is abnormal, pH is 7.5 and lactate level is 4. 

Do abnormal ABG and/or SL change disposition after a negative CT?