Two sisters arrive at your facility for tonsillectomies. A CRNA performs pre-anesthesia assessments for both girls, but order sheets are stamped incorrectly with the other's name. The lighter sister receives too much midazolam.

Drugs, surgery and children: often an error-prone combination. Let's review the five root causes behind most errors in pediatric medication administration.

Pharmacokinetics and pharmacodynamics
Simply put, drugs affect children more quickly and potently than they do adults. The number of products involved in perioperative medication errors is astonishing, as many as 600 in one study. This signals not only that the breadth of knowledge required for safe medication use is great, but also supports the ongoing need for readily available, up-to-date drug references that practitioners can easily access when caring for the pediatric patient.

Pediatric patients receive most perioperative products parenterally, a route of administration associated with extremely high bioavailability. Once the product enters the body, its movement (pharmacokinetics) and distribution depend on how efficiently blood flows to the desired area, whether the drug is water- or lipid-soluble, and the degree of protein binding. Once the drug provides the desired effect, it's excreted, either in complete form or more commonly through metabolism (often with the assistance of hepatic enzymes).

How the drug interacts in a biochemical or physiological effect is known as pharmacodynamics, which is best understood by looking at drug affinity, potency and efficacy. A drug that has an affinity (a degree of attraction) to a receptor and stimulates a receptor-specific response is called an agonist. An antagonist drug, on the other hand, binds to a receptor and prevents a biochemical reaction. Potency is the amount of drug needed in the bloodstream to achieve the desired response. Efficacy is the maximum response produced by a drug.

Dosing for a child's weight
Children aren't merely little adults. To successfully perform drug therapy, you must prescribe, dispense and administer the appropriate product in a safe therapeutic range for each patient. To do this, you must first have accurate patient weights.

Drug doses are often calculated as a combination of desired drug (in metric units such as milligrams) per kilogram of body weight. Many products are packaged in adult formulations; when these products are prescribed for children, you often must manipulate the product volume to obtain the desired concentration or amount. Pediatric providers commonly perform a series of calculations to determine the final dose, and each step in the calculation process represents an opportunity for error.

This is even more problematic in the OR because practitioners in multi-specialty facilities who don't specialize in pediatric patients have to manage patients of all ages. This makes pediatric dose calculations in the perioperative environment a low-volume, high-risk occurrence, especially when coupled with the hundreds of medication choices within this environment. Here are a few tips to make drug administration less risky and less complex:

• Double-check all calculations for accuracy. Using computer-assisted algorithms is ideal, but in their absence, independent double checks are fine. According to a 2002 United States Pharmacopeia report, 9 percent of pediatric medication errors were caused at least in part by miscalculation.
• Educate. Provide specific and ongoing training in product selection, product dosing and product administration to practitioners in this area.
• Standardize pre-printed orders. Pre-printed orders will only be helpful for day surgery units, post-anesthesia care units and pre-op holding, areas as they provide limited safety for those patients behind the pneumatic doors of the operating room and within the individual operative suite.
• Outline all medications to be used before the procedure. Armed with this information, the team as a whole can look out for the welfare of the patient and intervene when appropriate.
• Write down dose limits ahead of time and communicate them inside the OR. Often, when dosing is specified on a preference card, the order for drug administration is oral, but no one vocalizes the limit, which could lead to the administration of toxic levels of the medications.

Poor communication
Children are often unable (or unwilling) to communicate with the healthcare team, which makes patient- and family-centered care a priority. You must have know the family history, including known allergies, to provide safe medication use. Communication extends beyond the child and family to include all members of the healthcare team. Oral orders are common in perioperative care and are most susceptible to errors. Other forms of communication involved in medication errors include illegible handwriting, the use of trailing zeros and the improper use of abbreviations.

In all healthcare settings, patients (if appropriate to age) and parents or other caregivers should be provided oral and written information regarding

• medication information (name of product, how much to give, how often to give),
• common side effects,
• potential adverse events to monitor for,
• what to do if an adverse event occurs (immediate response, who to call, how to report an adverse event), and
• the proper disposal of unused portions of the medication dispensed.

Systems-related issues
Names, packaging and labeling of therapeutic products can either reduce or increase the likelihood of a medication error. Products used in perioperative care may share similar brand or generic names that sound or look alike.

If you have an automated dispensing device, review the medication order before administration. Ask the manufacturer for guidance in stocking and maintenance; don't store sound-alike and look-alike products in proximity to one another, and separate pediatric and adult formulations.

If you've adopted bar coding, you're already on the path to safer practice (see "Benefits of Bar Coding," March, page 26). For most of the perioperative environment, bar coding should provide a valuable safety net. The exception is the OR, where the safety value associated with bar coding extends only to the dispensing phase. In the OR, the scrub team removes products from their original packages (where the bar codes would normally be) and places them in sterile secondary containers, which must then be labeled. Labeling is time consuming, and the practice lends itself to shortcuts, actions that heighten the chance for error. Safe medication delivery within the operative sterile field could be enhanced if manufacturers made products available in individual sterile packaging and the appropriate mode of delivery for this environment. The surgical team could then use bar coding immediately before delivery to the sterile field.