Errors when prescribing

Errors can result when ambiguous orders are interpreted in a manner other than what the prescriber intended. Proper expression of doses is vital in a drug order. Pharmacists should be able to recognize improper expressions of doses, and the potential for error, when they see them. When the order is not clear, the pharmacist must contact the prescriber for clarification. Pharmacists and technicians should avoid using dangerous expressions of doses as they process orders, type labels, and communicate with others. The following examples include several improperly expressed orders that were reported to the Institute for Safe Medication Practices (ISMP) ... 

Continuing a GPs prescribing error when patient is admitted to hospitai... 

Refraction. The principles of optics are used in this clinical test to determine the eye s refractive error and prescribe corrective lenses to achieve the best possible visual acuity. Refinctive errors can be spherical or cylindrical. Spherical errors mean that the optical power of the eye is either too large or too small to focus light on the retina, which causes blurry vision. Spherical errors can be further classified into myopia (nearsightedness) or hyperopia (farsightedness). Cylindrical errors occur when the optical power of the eye is too powerfiil or too weak across one meridian, known as astigmatism. A phoropter, retinoscope, or automated refractor can be used to measure refractive error. 

For the sake of completeness, it is also useful to define at this stage the category of errors known as violations. Violations occur when a worker carries out actions that are either prohibited or are different from those which are prescribed by the organization and carry some associated risks. Since violations are deliberate acts, they are not, strictly speaking, errors. However, the violations category is useful when classifying human caused failures. 

Hence, for example, Var(fcmin) — (P — df jn + o(l/rp-). The standard deviation of min goes to zero as /n when n increases. This is much faster than 1/V prescribed to the deviation of the mean value of independent observation (the "law of errors"). The same asymptotic 1/m is true for the standard deviation of the second constant also. These parameters fluctuate much less than individual constants, and even less than mean constant (for more examples with applications to statistical physics we address to the paper by Gorban, 2006). 

Compliance is the third patient-related factor contributing to medication errors. One study found a 76 percent difference between medications patients actually are taking when compared with those recorded in their charts as prescribed. Two factors that contribute to this high rate of discrepancy include confusion that may accompany advancing age and the increase in the number of prescribed medications (Bedell et ah, 2000). Another study demonstrated that patient noncompliance played a role in 33 percent of hospital admissions (McDonnell, Jacobs, and McDonnell, 2002). 

Contact lenses can produce changes in corneal shape and/or corneal thickness substantive enough to cause lOP measurement error. This may be particularly true of patients who are prescribed orthokeratology for the management of refractive error. In addition, there is evidence that many soft lens wearers may develop corneal edema during the day. Low levels of contact lens-related edema (<5%) may produce a stiffening of the corneal tissue with a corresponding measured increase in lOP When edema levels increase beyond 6% to 10% (which is less common in contact lens wear), the cornea becomes substantially softer with subsequent lower measured lOP... 

Reason (21) has described a model for looking at human error that portrays a battle between the sources of error and the system-based defenses against them. This model is often referred to as the "Swiss cheese model" because the defenses against error are displayed as thin layers with holes that are described as latent error in the system. Figure 26.5 demonstrates the model as applied to medication error. Each opportunity for error is defended by the prescriber, pharmacist, nurse, and patient. When a potential error is identified and corrected (e.g., dose error, route of administration error) the event becomes a "near miss" rather than an ADE. In those cases in which the holes in the Swiss cheese line up, a preventable medication error occurs. The Swiss cheese model provides an interesting framework for research in this field. 

Independent verification assures that an error did not occur when the medication was prescribed by the healthcare provider. 

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