Disinfectants and antiseptics

Although heat is the best way of killing micro-organisms, you will have to use chemicals to kill them on a patient's skin, or on anything which heat might harm, such as drains or some suture materials. Heat destroys a cutting edge, so store your scissors in a chemical solution which will destroy bacteria. Classically, these chemicals are either antiseptics, which are safe to use on the surfaces of the body, or disinfectants, which are not. In practice, the distinction is not precise, and the only substances in the list below which cannot be applied to the body are saponated cresol (''Lysol'), formalin, and glutaraldehyde. There is an optimum antiseptic for each purpose, so try to use the right one.

Disinfectants have serious limitations and only work when the object they are disinfecting is clean[md]they are ineffective in the presence of blood or pus. So wash scissors and fine instruments carefully before you store them in an antiseptic solution. If possible, drains and other heavily contaminated pieces of equipment should be boiled or autoclaved after washing and before being immersed in these solutions. Afterwards, wash them well in sterile water before you use them. Catheters and tubes, etc., deteriorate in antiseptic solutions and are better autoclaved before use. Avoid cetrimide; it is mainly a detergent and chlorhexidine is better.

IODINE, tincture USP, one litre only. This is the best skin antiseptic. If necessary, make it by mixing iodine 2 g (if necessary 1 g), sodium iodide 2.4 g, spirit 50 ml and water 50 ml. Tincture of iodine readily evaporates and becomes concentrated; if it does, dilute it. It is still effective and is more economical when it is diluted with spirit until it is a light brown colour.

CHLORHEXIDINE gluconate solution BP (''Hibitane'), five litres only. Both chlorhexidine and cetrimide have so little effect on [f10]Pseudomonas [f09]that cetrimide can be used to select it from mixed cultures. Fortunately, spirit kills [f10]Pseudomonas[f09], so chlorhexidine should be made up in 70% spirit.

GLUTARALDEHYDE concentrate 50% w/w in water, five litres only. It is related chemically to formaldehyde but is less irritant. It is less stable but more active when buffered to pH 7.5 to 8 as in ''Cidex'. Used as a 2% alkaline buffered solution, glutaraldehyde comes nearest to being a chemical sterilant. It disinfects in 10 minutes, but it needs 10 hours to kill spores. It is very irritant, so keep it away from skin.

CRESOL and soap solution BP (''Lysol'), or some other phenolic antiseptic, ten litres only. Use this for disinfecting the tops of theatre trolleys and the floor, etc. Don't apply it to the skin. The concentration of phenolic antiseptics is important. Use them at a a concentration of 1% w/v active phenols. If solutions are too dilute bacteria grow in them.

DRESSING TRAYS, stainless steel, with lids, (a) 250[mu]200[mu]50 mm, six only. (b) 350mu[mu]300[mu]50 mm, three only. Fill the smaller trays with chlorhexidine solution or spirit. Use separate trays for sutures and needles, rubber drains, and dental needles and equipment.

SODIUM NITRITE TABLETS, 100 g. Alternatively, SODIUM NITRITE powder, 100 g. This is not an antiseptic, but a 0.4% solution of it in an antiseptic solution will stop steel instruments rusting.

ANTISEPTICS AND DISINFECTANTS SKIN. Any alcoholic solution will do. Alcoholic iodine is best: use it routinely, except in children, on the scrotum, and in allergic patients. 0.5% chlorhexidine in spirit is a less satisfactory alternative. Apply it to the skin after removing all traces of soap.

WOUNDS. There is no substitute for a scrubbing brush, plenty of water from a jug, and a thorough surgical toilet (54.1). Chlorhexidine is useful for cleaning the skin round a wound.

INSTRUMENTS, SUTURE MATERIALS, AND DRAINS. The following agents are effective against HIV and HBV, in addition to the classical pathogens. (1) 2% alkaline buffered glutaraldehyde is the best. (2) 5% formalin in 70% spirit. (2) A 0.5% solution of chlorhexidine in 70% spirit with 0.5% sodium nitrite. (This is in terms of the active agent.) (4) Plain 70% spirit.

Ten minutes is the absolute minimum time in these solutions, provided instruments are scrupulously clean, 24 hours is safer. Ideally, nothing should be considered ''sterilized' until it has been immersed for 24 hours. Wash all equipment well before using it.

CAUTION ! (1) Except for glutaraldehyde (which can be used for 14 to 28 days depending on the brand) make these solutions up freshly every week, and keep them covered to prevent the alcohol evaporating. (2) A ''wipe' is not nearly as good as a soak!

Fig. 2-8 OPERATIONS HAVE BEEN DONE UNDER A TREE. One eminent professor of International Health (Carl Taylor) recalls that during his days as a surgeon he had, on occasion, to release contractures on the steps of a temple! So there [f10]may [f11]be times when you have to operate in a tent or even ''on the kitchen table'. It has been said that a first class surgeon can operate in any theatre in any clothes[...] Kindly contributed by Imre Loefler. Drawn by Nette de Glanville, and reproduced with the permission of the Editor of the Transactions of the East African Association of Surgeons.