Letters

RAPID RESPONSES FROM BMJ.COM

Ask your pharmacist

Ask a medical student

How cold is cold?

H₂O₂ and blood stains

Ask your pharmacist

This article originally appeared in BMJ USA

EDITORCK Pager is correct in identifying the mechanism of blood staining as being erythrocyte lysis. The correct mechanism to prevent permanent staining is to prevent erythrocyte lysis. The lysis occurs when erythrocytes are exposed to hypotonic solutions like water.

The correct way to treat blood stains is to apply a hypertonic saline solution and provide gentle agitation in order that the cell structure is preserved. The cells can then be rinsed away to rupture somewhere else.

I would recommend that all doctors be equipped with a strong salt solution to apply immediately to the offending stains.

I am in no way connected to or sponsored by the salt industry.

Jim Latona, hospital pharmacist. 
Royal Lancaster Infirmary, UK jim.latona{at}l.bay-tr.nwest.nhs.uk

Ask a medical student

EDITORAs a final-year medical student, required to wear white shirts, I have unfortunately been splattered with blood on rare occasions. I have discovered, through trial and error, that the best remedy is normal strength hydrogen peroxide applied within 24 hours to the stained area. The stain immediately bubbles up and slowly dissipates.

Normal washing in hot or cold water results in a pristine white shirt.

At present I am unsure how this method works, and my Medline searches have proven unsuccessful. Perhaps the authors could try this revolutionary technique on their pillowcases in the future.

I have no competing interests nor any affiliation with hydrogen peroxide companies.

Kirby F Sebro, final-year medical student. 
Port-of-Spain General Hospital, University of the West Indies, Trinidad kirby_sebro{at}hotmail.com

How cold is cold?

EDITORLast year I moved from Yorkshire to Alice Springs. One unexpected challenge was finding that removing blood stains from clothing became difficult. A long soak in cold water doesn't work any more. Why? Is Australian blood different?

The answer seems to be that the cold water is differentit isn't actually cold. The warm climate means that the water in the tank is similarly warm.

Pager does not refer to the temperature of the water on the cold-water cycle. Was it cold, as it would be in Yorkshire, or tepid, as in Alice Springs? It costs more to use hot waterperhaps this otherwise neat piece of research should be repeated in colder climes, including a check on the water temperature, before we all turn up the heat.

Susan Wearne, GP educator. 
Centre for Remote Health, Alice Springs, NT, Australia susan.wearne{at}flinders.edu.au

H₂O₂ and blood stains

EDITORI believe oxygen acts as a bleach for many pigments. I also believe hydrogen peroxide reacts with hemoglobin resulting in rapid degradation into H₂O and O₂ie, liberating free oxygen.

The rule I was taught about temperature didn't have to do with washing, but with soaking: soak the stain in cold water, then wash it however you normally would.

Read Weaver Schusky, private practice. 
Somerville, Mass, USA rweaver{at}igc.org