Christmas tree fir green is not the intensive care unit's favourite colour.

A patient in her 60s presented to a district general hospital with headache, loss of consciousness, and vomiting. She was diagnosed with a subarachnoid haemorrhage secondary to an anterior communicating artery aneurysm and was transferred to a tertiary unit for coiling of the aneurysm under the neurosurgical team. She was intubated and had close observational monitoring, where it was noted that her oxygen saturations, obtained using finger-pulse oximetry, varied between 94% and 100%. Each fingernail had a different acrylic nail polish colour which we believe resulted in these inconsistent readings. The dark forest green colour consistently gave a significantly lower oxygen saturation reading when compared with our control, which was the arterial blood gas oxygen saturation, whereas orange and purple were most like our control. We therefore found that the varied colours painted on acrylic nails affected oxygen saturation readings differently. This difference could affect treatment pathways for patients in theatre and the intensive care unit.