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AANS Neurosurgeon | Volume 25, Number 2, 2016


The Many Definitions of Concomitant Surgery

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The topic of multiple surgical procedures occurring at the same time and attended to by the same surgeon has become of greater societal and clinical interest in the past one to two years partly because of publications by the Spotlight Team from the Boston Globe (1). Unfortunately, at least a portion of the debate surrounding this topic is confused because of the use of variable terminology in naming and attempting to describe these types of operations. Some of the terms which have been offered as descriptive of the practice include concomitant surgery, simultaneous surgery, overlapping surgery, concurrent surgery, staggered-start surgery and sequential surgery. This brief article seeks to help define the terms which have been used by varying parties during previous and current discussions. Each of the definitions below was obtained by reviewing the online Oxford English Dictionary:

Concomitant can function as both an adjective and a noun. As an adjective, concomitant means going together, accompanying, concurrent, attendant as well as occurring side by side or unseparated. As a noun, concomitant means an attendant state, quality, circumstance or thing; an accompaniment or a companion. Synonyms include accompanying, coincident, adjoining and co-occurrence.

Simultaneous is an adjective meaning existing, happening, occurring, operating, etc., at the same time; coincident in time. Synonyms for simultaneous include concurrent and coincident.

Overlap can function as either a noun or a verb. As a noun, overlap means an occurrence or instance of overlapping; the point at or degree by which one edge or thing overlaps another. As a verb, overlap means to fold or wrap over, to cause a thing to lie over another thing partially or to cover and extend beyond a thing. 

Concurrent can function as both an adjective and a noun. As an adjective, concurrent means running together in space, as parallel lines; going on side by side, as proceedings; occurring together, as events or circumstances; as well as covering the same ground; having authority or jurisdiction on the same matters. As a noun it refers to a concurrent circumstance, a contributory cause or to a person or thing coexistent or contemporary with another. 

Stagger has a variety of uses (both noun and verb), but those of most interest to the current discussion include its use as a verb meaning to arrange in zig-zag order, or in positions alternately on the one side and the other of a median line, to arrange (as in dates, times, etc.) so that they do not coincide; to arrange (an event or action) so that its implementation is spread over a period of time, or so that it is performed by different persons at different times.

Sequential has the following meanings: that which follows as a sequel to, of two or more things: forming a sequence; resultant, consequent; and it can also mean, as in a sequential circuit (from electronics) a logic circuit whose output depends on the order or timing of the inputs.

In the Boston Globe publication “Clash in the Name of Care,” the authors frequently use the terms concurrent, simultaneous and double-booking to describe scenarios where an attending surgeon has scheduled multiple surgical cases that will occur during the same time period and which will overlap at least partially (1). Separately, Mello and Livingston assert that “overlapping or concurrent operations involve scheduling substantive portions of two or more surgeries to occur during the same time (2).” Unfortunately, neither of these articles provides clear understanding of the nuances between the words defined above. 

More Definitions 
Additionally, there are other terms which bear scrutiny with regard to this debate. Perhaps most importantly, but not clearly delineated in the literature are the concepts of “essential” (or critical) parts of a surgical case versus “non-essential” parts of a case. Without attempting to actually delineate what makes one portion of a case essential versus another portion non-essential, perhaps we can at least assert that essential or critical portions of the case require the attending surgeon to be present and actively participating in surgical decision making and the manipulation of tissues; whereas, non-essential portions of the case do not require the attending surgeon’s physical presence and can be completed by some other member of the surgical team.

Similarly, there is likely a role for distinguishing between direct supervision, indirect supervision and general oversight by the attending surgeon. To be considered direct supervision, the attending surgeon must be physically present and directly observing the conduct of the operation. Indirect supervision would then mean that a designee of the attending surgeon is performing a portion of the operation without the direct presence or observation of the attending surgeon. General oversight by an attending surgeon would then refer to a case where the surgical designee (think for example post-graduate fellow) completes the entire procedure and there is no implied or mandated requirement for the physical presence from the attending surgeon “overseeing” the operation – here the attending surgeon could be considered an available resource who will only be called upon if something unusual or more complicated than expected is encountered. Additionally, the Boston Globe piece “Clash in the Name of Care” reports on “procedural overlap” which they define as instances involving at least one patient with an open incision while the second surgery is underway (1) – which apparently is to help differentiate that type of case overlap with what seems to be purported as a more common type of case overlap where the surgical site is closed in one case before the next procedure begins (though it is not clearly defined whether the next procedure is considered to begin with induction of anesthesia or with the surgical incision).

A Visual Representation 

Internal Image-resized

Figure 1. Potential scenarios for scheduling consecutive or concurrent cases with or without overlap (A versus B-G) and with strictly separated (A, B) essential/non-essential portions of the cases versus cases where part of the critical portion of the case can be overlapped with a non-essential portion of another case (C, D, E and F) or can be simultaneous with the critical portion of another case (G).

The following figure is meant to provide a visual representation of the arrangement of cases that might be encountered with one attending surgeon providing care to patients in two separate operating rooms during the course of one day. The bubbled and shaded portion of each line is meant to depict the essential or critical portion of each case. Each pair of lines/bubbles (blue and red) represents the two operating rooms and the time relationship between the cases in each. Figure 1A depicts “sequential” but non-overlapping cases. In this example, no portion of a subsequent case begins until all of the essential and non-essential components of the case before it are completely finished. Figure 1B depicts sequential cases which are “staggered” to start at times which allow for overlap of the non-essential portions of the cases only. 

As an example, this scenario might envision the beginning of induction of anesthesia, placement of a foley catheter and perhaps even positioning of a patient in the second operating room while the non-essential components of the first case, such as bandaging a wound and arousal from anesthesia, are being completed. Figure 1C goes further than Figure 1B in showing that the non-essential components of a subsequent “staggered” case can overlap with the essential/critical portion of the prior case. In this example the patient in the second operating room might be going to sleep and positioned while the attending surgeon is still resecting tumor or clipping an aneurysm in the first case. 

Figures 1D, 1E and 1F illustrate “concurrent” case configurations where there is progressively increasing overlap between at least one long case and other cases – either shorter in total duration or with longer periods of non-essential work for the attending in question. Figure 1D might depict an anterior/posterior cervical fusion with a small procedure set up to occur in a second room during the time of flipping the first patient from one position to the next in the first OR. Figure 1E shows a succession of small cases that occur during down periods before, between and after periods of essential work in the room with the bigger case. Figure 1F depicts two longer surgeries, however, one of the cases may be a combination case with another service (i.e. combined ENT and neurosurgery case) and the neurosurgeon is only needed for a portion of that overall case. Finally, figure 1G is meant to illustrate what might be the most controversial scheduling practice. In this example, there are two surgeries which will essentially overlap completely and there is no clear way for the attending surgeon to be present for large portions of the essential elements in at least one of the cases due to literally “simultaneous” and equal obligations in the other operating room.

Let’s Reivew
In order to help clarify the discussion regarding double-booking cases, the following recommendations for terminology are offered. The term sequential will be used to describe cases that follow one after the other as in Figure 1A. In sequential cases, there is no overlap between the ending of one case and the beginning of the next case. Staggered start cases (Figures 1B and 1C) are those which do not start at the same time but which can have some overlap between the ending of one case and the beginning of the next case.

The amount and type of overlap (essential portion versus non-essential portion of the case) are not specifically defined by the term staggered start. Overlapping is a generic term which describes two cases which have any portion of their duration during the same time period. Overlapping could be reasonably used to describe any of the scenarios depicted in Figures 1B-1G. Grammatically, the terms concurrent and simultaneous cases are synonyms and could potentially be used to describe scenarios where at least one surgical case is completely overlapped from a time standpoint by another case as in Figure 1D or Figure 1E or where two cases of essentially the same total duration are close to completely overlapping one another as in Figures 1F and 1G. However, due to the already apparent difficulty in accurately describing the temporal relationships between surgical cases in multiple operating rooms; it is recommended that the term concurrent be used to described cases as illustrated in Figures 1D, 1E and 1F and that the term simultaneous be reserved to describe cases where all or nearly all of the essential and non-essential portions of two separate cases are directly overlapping (Figure 1G).

1. Abelson, J., Saltzman, J., Kowalczyk, L., & Allen, S. (2015). Clash in the name of care. Boston Globe.

2.  Mello, M. M., & Livingston, E. H. (2016). Managing the risks of concurrent surgeries. Jama, 315(5), 1563-1564.


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