Correspondence  |   October 2004
Intraservice Time Is Not a Proxy for Operating Room Time
Author Affiliations & Notes
  • Norman A. Cohen, M.D.
  • * Good Samaritan Hospital, Corvallis, Oregon.
Article Information
Correspondence   |   October 2004
Intraservice Time Is Not a Proxy for Operating Room Time
Anesthesiology 10 2004, Vol.101, 1041. doi:
Anesthesiology 10 2004, Vol.101, 1041. doi:
To the Editor:—
Dr. Abouleish et al.  1 should be commended for their efforts to quantify staffing costs associated with longer-than-average surgical case durations. Identifying these costs and subsequently minimizing their impact may have a salutary financial effect on institutions, such as academic medical centers, where longer case duration is the norm.
In determining “National Average Time” by Current Procedural Terminology procedure, the authors use the intraservice time reported by the Centers for Medicare and Medicaid Services as a proxy for “in-room” time. The Centers for Medicare and Medicaid Services time values are derived from surveys conducted for the American Medical Association-Specialty Society Relative Value Update Committee and the original Harvard Resource-Based Relative Value System studies. In both cases, the intraservice period “includes all ‘skin-to-skin’ work that is a necessary part of the procedure.” Scrubbing, prepping, patient positioning, and waiting are components of the preservice period. Dressing and patient repositioning (e.g.  , prone to supine) after skin closure is part of the postservice period. All of these activities actually contribute to the total “in-room” time for nearly all surgical procedures.
The authors compared the Centers for Medicare and Medicaid Services intraservice time to the total in-room time obtained from the operating room information systems from the two institutions studied. This calculated time difference is a dependent variable in the additional staffing costs calculated by the authors. Errors in the time data will result in erroneous calculations of staffing costs attributable to longer-than-average duration.
Unfortunately, use of intraservice time as a proxy for operating room time will systematically underestimate national average operating room time because of the exclusion from consideration of all in-room patient time outside of the “skin-to-skin” period. Many procedures, commonly performed in academic medical centers, require time-consuming positioning, skin preparation, and draping, which consume a significant proportion of in-room time. Frequently, anesthesiologists place invasive monitoring devices or insert catheters for postoperative pain management in the operating room. Depending on the practice at the two academic medical centers studied, these anesthesia interventions may also contribute to in-room time outside of the “skin-to-skin” period.
One other aspect of the methodology also deserves comment. In the Methods section detailing “Surgical Case and Operating Room Data,” the authors note that the surgical Current Procedural Terminology code was obtained from the anesthesia billing database and was the “primary surgical” code for which the anesthesia service was billed. A significant proportion of surgeries involve multiple procedures. Even procedures such as coronary artery bypass grafting or spinal decompression, which would be considered a single surgical intervention to many anesthesiologists, are reported with multiple Current Procedural Terminology codes. By only considering the primary surgical procedure code in determining the intraservice time, the authors have failed to include the intraservice times associated with the Current Procedural Terminology codes also reportable in cases involving multiple procedures. The implication of this choice is a further overstatement of the difference between site-specific and average national time data as defined in the study.
It is our hope that understanding both the definition of a key data element used in this analysis as well as the impact of multiple procedures on total average in-room time will allow the authors to further refine their model, thus resulting in a more accurate and more useful assessment of the impact of longer duration procedures on staffing costs.
* Good Samaritan Hospital, Corvallis, Oregon.
Abouleish A, Dexter F, Whitten C, Zavaleta J, Prough D: Quantifying net staffing costs due to longer-than-average surgical case durations. Anesthesiology 2004; 100:403–12Abouleish, A Dexter, F Whitten, C Zavaleta, J Prough, D