A person’s scalp is torn open when the metal stairs of their recreational vehicle fall on their head. They are immediately taken to the emergency department, where a CT scan comes back normal and no skull damage is found. The care team turns their attention to the wound, but the anesthetic doesn’t appear to be working. [**A nurse shares the case on Figure 1, explaining the dilemma:**](https://app.figure1.com/rd/images/5b3c099898ef961100069fe5?utm_campaign=Acquisition&utm_medium=web&utm_source=cases&utm_content=pcp-signupTop)

> “Having a difficult time numbing him up. Already used 17 cc of lido [lidocaine]. Any tricks someone would like to share?”

**An emergency physician gently questions the nurse:**

> “Make sure you are not injecting saline, 17 cc of lido should have done the job. But I am just kidding of course. Wouldn’t be a terrible idea to consciously sedate him.”

A neurologist recommends lidocaine with epinephrine, a vasoconstrictor that one nurse refers to as “the chemical tourniquet.” Several other healthcare professionals suggest other anesthetics.

**Eventually, a technician notices something in the case photograph:**

The technician shares two studies on the subject, titled [Midazolam Causes Less Sedation in Volunteers With Red Hair](https://www.ncbi.nlm.nih.gov/m/pubmed/14709456/) and [Anesthetic Requirement is Increased in Redheads](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1362956/).

> “Patient seems to have reddish hair, which is associated with a gene that causes resistance to sedation and analgesics. Be careful with this one.”

Another nurse concurs: “It’s truly a thing. I had a tiny 8-year-old girl who got enough sedation to knock a wrestler out because she was a redhead.”

The patient’s nurse indicates that this was in fact the case. In the words of one medical student: “Wow! This is new info for me. Thank you for sharing.”