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Patient Safety Scenario #15: Defense in Depth — Checks and Backup Checks
Captain Rick Saber at the controls.

This essay is the 15th installment of the monthly Patient Safety essays, produced by the Patient Safety Subcommittee of the Ethics and Professionalism Committee. The essays are written in the spirit of the aviation industry’s “Black Box Thinking” in order to inform and improve our medical safety record. To read earlier essays and learn how to contribute, please click here.

Data analysis of aviation accidents and near misses has demonstrated that no matter how qualified or experienced the pilot, mistakes can still happen. In fact, the worst aviation accident in history was caused by the most qualified pilot in the airline, Captain Jacob Veldhuyzen van Zanten. He was not only the chief safety officer, he also the chief flight instructor, the pilot who gave all the other pilots their annual check rides.1 James Reason, PhD, is an industrial psychologist whose specialty is human error.2 He notes that because all humans make mistakes, all systems that involve humans will therefore experience errors. The goal therefore cannot be to prevent all errors, it is to catch all errors before they affect the mission of the team. He calls this “defense in depth.” The analogy for this concept is called the Swiss Cheese Theory Of Errors.3 Incorporating the concept of “defense in depth” in the operating room is essential for patient safety. These two scenarios demonstrate how simple errors can be caught with a culture of “defense in depth,” in which mutually supportive team members check on each other. They also highlight how the surgeon can be an effective team leader by taking the occasion of an error to teach the team why a particular protocol is used. If the teaching is done well and with respect, it enhances patient safety and the ability of the team to function in the future.

David Nelson, MD Chair, Patient Safety Subcommittee
Scott Lifchez, MD Co-Chair, Ethics and Professionalism Committee
Julie Adams, MD Co-Chair, Ethics and Professionalism Committee

Scenario One

A surgeon has had the same circulating nurse and the scrub tech for several years, so everyone on the team knew the routine. When occasionally there was a different nurse or tech in the room for a day, the regular team would routinely look over all of the upcoming cases to make sure that the medications, equipment, and implants were ordered/requested in time for each surgery. 

A new nurse team leader in the OR was assigned for the hand service. She was one of the nurses who had often been circulating in the OR when the regular circulator was away, and she was somewhat familiar with the surgeon’s practice and equipment. 

The first case of the day was scheduled for an extensor tenolysis and MP capsulotomy under WALANT. In the preop area the nurse team leader handed the surgeon a syringe with a label “1% lido w epi and Marcaine” along with her initials and the date. Per his routine practice, the surgeon injected the surgical field in the preoperative area, and the team and patient proceeded to the OR. Prior to incision, the surgeon confirmed the patient was anesthetic at the surgical field. As the surgery began, the field appeared significantly bloodier than the surgeon expected it to be. The surgeon confirmed that the label on the syringe used for the injection stated that there was epinephrine in the solution. The surgeon asked to see the original medication bottles. The lidocaine bottle appeared similar to the bottles with epinephrine that were regularly used, but on close inspection, the bottle used for that day did not have epinephrine. The new nurse was not keyed in to notice the subtle but important differences between the two bottles. Besides, as the nurse observed, “No one ever uses epinephrine in the hand.” The surgeon was able to use a sterile tourniquet briefly to complete the operation while still keeping the patient comfortable, and use the occasion as an opportunity to teach the team about the use of epinephrine in the hand.

The acceptance of use of epinephrine in the hand has been very familiar to hand surgeons for well over a decade. Most nurses have been taught, just as hand surgeons were taught back in medical school, the old axiom of “fingers nose, toes…” for places not to use epinephrine. Not all OR staff have been educated about why in the past it was such a strong rule to never use epinephrine, and now it is common to use it. This dramatic change in protocol can be rather confusing to the staff if it is not properly explained. In addition, it is not clear to all members of the team why epinephrine is used for one particular case and not another. The surgeon took this opportunity to show good team leadership by explaining why the strict rule against epinephrine in the fingers had changed and the evidence to support its safe use. The surgeon also explained that in some cases, epinephrine is used to prolong the duration of the local anesthetic effect. In some circumstances, as was the case for the current case, the epinephrine was being used for direct vasoconstriction in order to avoid the need for a tourniquet. The OR team enjoyed the brief lesson, and felt respected that the surgeon felt it was important to teach them the nuances in the use of epinephrine. In the OR, respect is rocket fuel.

In addition, this became an opportunity to discuss with the team the need for accurate review of what medications were ordered (via readback, also called “closed loop communication”) and the medication labels, as well as to make sure all team members understand why epinephrine is being used in the injection. Ideally, all team members, including the person injecting the local anesthetic, should be looking at the original medication bottle. 

Scenario Two

Even when medication and equipment supplies for a case are reviewed, this may not always prevent an intraoperative concern.

A patient was scheduled to undergo four-finger MP implant arthroplasty for rheumatoid arthritis. The surgeon checked the equipment sets before coming back to the room with the patient. The implants were kept in a particular container in the equipment room. The circulating nurse and the surgeon confirmed the container was on the case cart and confirmed the range of sizes that were expected to be needed were present. Normally, the surgeon uses implant sizes 4-7 for finger MP joints, and only rarely a size 3 for the small finger MP only. There were 3 permanent implants available each in sizes 4 through 7. Preoperative imaging and exam indicated the patient’s hand was of average size. As the team started the case, the surgeon saw that the medullary canals of the proximal phalanx bases were narrower than the preoperative imaging suggested they would be. As the surgeon broached the canals for the implants, it became clear that smaller implant sizes than usual for MP joints would be needed for this patient. The circulator went to retrieve the implants from the container and saw that there was only one size 3. Initially, it appeared that 2 fingers would need a size 3 implant. When final broaching was completed, one of the two fingers could accommodate a size 4 implant, and so there were enough of the permanent implants for all of the digits. 

Both of these cases highlight the importance of personally verifying equipment and medications for each case prior to the patient coming in the room. In the first case, looking at the original bottle would have shown that there was no epinephrine in the local anesthetic. In the second case, confirming that multiple copies of each implant size (including sizes smaller than the usual sizes used) were present prior to the start of the case would have alleviated the concern that arose when the surgeon thought they needed one more copy of a permanent implant than had in the size needed. AORN guidelines for circulating nurses include verification that equipment and medications needed are present and correct,4 but the surgeon should still personally verify this as well to confirm that everything needed for the case is present prior to the start of the case5

The surgeon is ultimately responsible for the patient in the OR and their outcomes afterwards, but all team members in the preop area, the OR, and the PACU can have direct effects on the patient’s care. The Joint Commission also provides patient materials for self-advocacy to prevent surgical errors such as wrong site surgery5. As the team leader, the surgeon can help prevent errors like those shown above by promoting good communication and trust between team members. All team members need to feel comfortable speaking up if they see a problem or identify a concern. In addition to the circulator and OR team leader, the surgeon should also be verifying medications and equipment. As illustrated by the second scenario above, the surgeon should also ensure they have appropriate backup plans/equipment/implants on hand for circumstances where an unexpected intraoperative finding may mandate a change in plan or intraoperative equipment/implant needs.


1  Accessed 8/28/19

2 Accessed 8/28/19

3   Accessed 8/28/19

4  Accessed 8/28/19

5  Accessed 8/28/19

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