Q A patient asked me about something she picked up from a TV program: It seems a nurse was recommending Johnson's Baby Shampoo be used to clean a surgical wound when recuperating at home. Have you ever heard of that? Is it safe and effective?

A I've never heard of this. You should keep the surgical site clean post-op, but most surgeons will recommend soap and water. I presume that because baby-formula shampoo is mild, someone thought it would be a good choice, and some well-meaning but bad advice was born. Without knowing the exact ingredients in the shampoo, I wouldn't recommend that anyone use baby-formula shampoo to clean surgical wounds. I assure you that Johnson & Johnson would not and cannot recommend that its shampoo be used for that application; doing so just might throw the shampoo into the medical-device category of products subject to FDA regulations.

Don't tell your patients to use any products for surgical-wound cleaning other than soap and water and those designed for the purpose.

A sterility guarantee
Q We have a debate about the circuitry set for the perfusion equipment connected to our heart-lung bypass machine. The equipment is set up in advance to be prepared for emergency cases. How long can the sterility of the circuitry set be guaranteed if it's set up in advance? Are there guidelines on the time a sterile delivery pack can be opened when waiting for the next case?

A These questions cover several situations in which items that need to be sterile at the time of use are, for convenience and expediency, left open to the environment before use. This is not unusual. Surgery departments, CV labs and areas that deliver emergency care have the same concerns. Let's deal with the easy one first.

There's a popular misconception that there is a magical something called a sterile field. Unless the field is under Class 100 laminar-flow conditions, it is susceptible to contamination as soon as it is opened to the environment. The more air movement around this field, the higher the probability of contamination. Some practices include locking the door and not letting anyone in the so-called sterile-field room. Others say it will be sterile as long as there is someone standing there watching it. A more common practice is covering the items that are laid out with a sterile drape.

None of this guarantees sterility. A locked room will necessarily have air movement caused by environmental services. Are the incoming ducts clean and filtered? Is the ambient air in the room sterile? Does someone's standing there bring more environmental contamination to the area? Is the sterile drape really sterile?

If you are so concerned about sterility, here's the rule to follow: If the items must be sterile, leave them in their sterile packaging until as close to the time of use as possible.

The extra-corporeal circuit used in coronary artery bypass surgery is unique. The surgery is increasingly performed without an extra-corporeal circuit. A heart-lung machine typically is kept on standby for safety, but rarely used. The tubes of the machines are currently discarded after every operation. The cost of this surgery is high enough and could be reduced if the machines could stay on standby for longer periods of time.

One investigation into how long the intra-tube fluid remained sterile found that 72 hours was the benchmark.1 Researchers tested four machines. The tube system was fixed and filled with priming solution. Samples of intra-tube fluid and fluid from the fluid bags were taken after zero, 12, 24, 36, 48 and 72 hours. Microbiological cultures were performed by direct inoculation and membrane filtration and incubated up to 14 days. Endotoxin levels were also determined. The results showed that bacteria were grown from two samples only and were considered as contaminants. Endotoxin concentrations never exceeded acceptable levels. Their conclusion: keeping heart-lung machines on standby for 72 hours was probably safe (key word: probably).

This study reminded me of one done in 1971 by the CDC on shelf-life of muslin-wrapped sterile packages. Those results as well as the results in the aforementioned study can only be reproduced if all the environmental conditions that prevailed at the time of the study remain the same. That is not very likely to happen. Any study that attempts to relate the maintenance of sterility to length of time is going to be of little value since the loss of sterility is not related to time - loss of sterility is related only to the events that occur to and around the sterile items.

If this is a problem in your facility, and you want to be able to anticipate what would happen in an emergency, measure the time required to set up the machine against the time required to prepare the patient. I think you'll find there is enough time for machine set-up, provided you have the machine and tubing ready. There are no guarantees when it's set up in advance.

Reference:
1. Witschi, A et al in Infection. 2003 Oct;31(5):350-2.