by Dev Raheja, Associate Editor, and Maria C. Escano, M.D., Baltimore, Maryland

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At Tripler Army Medical Center, a newborn baby went into a coma with severe brain damage. Reports claim that the medical personnel mistakenly gave the newborn carbon dioxide immediately after birth instead of oxygen. Sources report that the operating room may have been set up incorrectly [Ref. 1]. This incident highlights the vulnerability of humans, as well as systems. The utilization of human factors engineering can prevent or minimize the impact of such incidents. This incident prompted a vigilant effort to evaluate systems that can prevent such errors, creating checklists and eliminating the use of free-standing tanks.

Principles of Human Factors Engineering (HFE)

Human factors engineering focuses on how people interact with tasks, machines (or computers) and the environment. Every person has limitations and capabilities. Human factors engineers evaluate "human to human," "human to group," "human to organizational" and "human to machine (computers)" interactions to better understand these interactions and to develop a framework for evaluation [Ref. 2]. But HFE in practice goes beyond this definition. It attempts to mitigate the mishaps after the evaluation. This can have huge ramifications in healthcare delivery.

Errors are bound to occur. Even the most knowledgeable and experienced make their share of mistakes. The best evidence suggests that healthcare providers are wrong five to 10 percent of the time, according to Mark Graber, chief of medical service at the Northport, New York VA Medical Center [Ref. 3]. However, 85 percent of the time, the system is to blame because of improper design [Ref. 4].

Therefore, improving systems safety should be the focus to prevent harm. The first step is understanding various sources of human errors.

Sources of Human Errors

The following list includes some of the major sources of errors, including simple day-to-day examples and healthcare scenarios [Ref. 5]. Each healthcare facility can benefit from this list, when it is used as a starting point to recognize potential sources of error and to modify systems to eliminate inadequacies.

• Errors of substitution: Hot water is turned on instead of cold water during a shower.
• Errors of selection: Carbon dioxide is selected instead of oxygen for a patient.
• Errors of reading: A medication dose written for 1.0 mg is read as "10 mg."
• Errors of oversight and omissions: A nurse may simply forget to give an antibiotic after a surgery.
• Errors of irritation: A caregiver may perform the wrong task when distracted and irritated with too many alarms and interruptions.
• Errors of warning: Errors can occur when warning signs are not clear or require too many steps to follow in the instruction manual.
• Errors of alertness: Fatigue from working consecutive multiple shifts can decrease alertness.
• Errors of interchangeability: Connecting an oxygen hose to the nitrous oxide source in anesthesia equipment can occur when the fittings on both gases are the same.
• Errors of lack of understanding: An improperly trained staff is likely to make mistakes during emergencies.
• Errors of haste: A caregiver unable to perform tasks in an allocated time is likely to skip seemingly minor tasks, such as checking patient identification prior to medication delivery.
• Errors of sequencing: A medical technician may decide to shorten the task, perform the work out of sequence from a required checklist and cause errors.
• Errors of overconfidence: This can happen when a provider recognizes a constellation of familiar symptoms and hastily makes a diagnosis, which can be wrong when a list of other possible differential diagnoses is not considered.
• Errors of reversal: A caregiver may increase the oxygen delivery in a mechanical ventilator instead of decreasing it when he is unaware of whether to turn the control knob clockwise or counter-clockwise.
• Errors of unintentional activation: A caregiver may inadvertently flip a life support switch to OFF instead of ON.
• Errors of mental overload: A pharmacy technician prepared a chemotherapy solution with a 20% sodium chloride concentration instead of 0.9 %, resulting in a fatality. Investigation revealed that she was distracted while working on her wedding plan [Ref. 6]. Her supervising pharmacist had to serve six months of jail time. He overlooked her work because his own workload had increased due to the pharmacy computer system shut-down.
• Errors of physical limitations: Instruments may be designed for those with bigger hands and cause undue discomfort to those with smaller hands. Another example may include a short person attempting to reach high up for an object, causing an accident.
• Errors of casual behavior: Sometimes, a caregiver may not take a task seriously. A caregiver can spend too much time casually talking about his extra-curricular activities and fail to deliver a medication correctly. Another example is a caregiver who fails to wash his hands before entering a room in the ICU and caring for a patient.

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