ACE 19A Sample Question
Patients with red hair undergoing surgery and anesthesia are MOST likely to exhibit which intraoperative finding?
A. Increased risk for postoperative bleeding X
B. Increased minimum alveolar concentration (MAC) requirement X
C. No significant effect ✔
Read the discussion below.
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The genetic basis for red hair resides in variant alleles of the melanocortin-1 receptor (MC1R). There is little indication for a direct link between MC1R and the central nervous system. MC1R binding has been seen in the pituitary, glial cells, and cells in the periaqueductal gray. MC1R belongs to a family of melanocortin receptors, some of which are involved in pain perception. In that regard, sensitivity to pain in individuals with variant MC1Rs has been investigated with conflicting results.
In a 2004 study, desflurane minimum alveolar concentration (MAC) was shown to be higher in women volunteers with red hair (MACdesflurane, 6.2%) than those with dark hair (MACdesflurane, 5.2%). The study used the appropriate up-and-down method to measure MAC, which was presumed to be lower than the accepted value because electrical stimulation was used instead of the traditional surgical incision. However, a 2012 study showed no differences in overall MAC requirements across a wide range of surgical cases.
The presumed phenotype of excessive bleeding and red hair color has been investigated by studying the differences between coagulation parameters and von Willebrand factor measurements in patients with different hair colors. There is no laboratory evidence that there is a bleeding diathesis associated with hair color. As there are 2 studies indicating an increased risk of hernia formation in red-haired individuals, the possibility exists that there may be links with collagen synthesis, which may in turn affect vascular structures. A single, small report showed no evidence of increased post-tonsillectomy hemorrhage in red-haired children.
- Liem EB, Lin C-M, Suleman M-I, et al. Anesthetic requirement is increased in redheads. Anesthesiology. 2004;101(2):279-283. doi:10.1097/00000542-200408000-00006
- Liem EB, Joiner TV, Tsueda K, Sessler DI. Increased sensitivity to thermal pain and reduced subcutaneous lidocaine efficacy in redheads. Anesthesiology. 2005;102(3):509-514. doi:10.1097/00000542-200503000-00006
- Andresen T, Lunden D, Drewes AM, Arendt-Nielsen L. Pain sensitivity and experimentally induced sensitization in red haired females. Scand J Pain. 2011;2(1):3-6. doi:10.1016/j.sjpain.2010.08.005
- Myles PS, Buchanan FF, Bain CR. The effect of hair colour on anaesthetic requirements and recovery time after surgery. Anaesth Intensive Care. 2012;40(4):683-689. doi:10.1177/0310057X1204000415
- Robinson KC, Kemény LV, Fell GL, et al. Reduced MC4R signaling alters nociceptive thresholds associated with red hair. Sci Adv. 2021;7(14):eabd1310. doi:10.1126/sciadv.abd1310
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