© 2015 Wiley Periodicals, Inc.
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ACQUIRED CARDIOVASCULAR DISEASE ORIGINAL ARTICLE _____________________________________________________________
‘‘Knife to Skin‘‘ Time Is a Poor Marker of Operating Room Utilization and Efficiency in Cardiac Surgery Suvitesh Luthra, F.R.C.S.(CTh).,* Omar Ramady, M.B.B.S.,* Mary Monge, M.B.B.S.,* Michael G. Fitzsimons, M.D.,y Terry R. Kaleta,* and Thoralf M. Sundt, M.D.* *Division of Cardiac Surgery, Massachusetts General Hospital, Boston, Massachusetts; and yDivision of Cardiac Anesthesia, Massachusetts General Hospital, Boston, Massachusetts ABSTRACT Background: Markers of operation room (OR) efficiency in cardiac surgery are focused on ‘‘knife to skin’’ and ‘‘start time tardiness.’’ These do not evaluate the middle and later parts of the cardiac surgical pathway. The purpose of this analysis was to evaluate knife to skin time as an efficiency marker in cardiac surgery. Methods: We looked at knife to skin time, procedure time, and transfer times in the cardiac operational pathway for their correlation with predefined indices of operational efficiency (Index of Operation Efficiency - InOE, Surgical Index of Operational Efficiency - sInOE). A regression analysis was performed to test the goodness of fit of the regression curves estimated for InOE relative to the times on the operational pathway. Results: The mean knife to skin time was 90.6 W 13 minutes (23% of total OR time). The mean procedure time was 282 W 123 minutes (71% of total OR time). Utilization efficiencies were highest for aortic valve replacement and coronary artery bypass grafting and least for complex aortic procedures. There were no significant procedure-specific or team-specific differences for standard procedures. Procedure times correlated the strongest with InOE (r = S0.98, p < 0.01). Compared to procedure times, knife to skin is not as strong an indicator of efficiency. A statistically significant linear dependence on InOE was observed with ‘‘procedure times’’ only. Conclusions: Procedure times are a better marker of OR efficiency than knife to skin in cardiac cases. Strategies to increase OR utilization and efficiency should address procedure times in addition to knife to skin times. doi: 10.1111/jocs.12528 (J Card Surg 2015;30:477–487) Cardiac surgery is a complex pathway involving coordination of multiple steps and team members. The operational costs need to be balanced against the fixed costs of resources and manpower utilization. For most cardiac surgery cases, resource utilization in terms of materials and equipment used is standard and predictable. Manpower resource utilization and time remains an important variable leading to cost escalation, over runs, and inefficiency in the operation room (OR).1–3 Surgical time utilization remains central to OR efficiency. Studies of both technical (based on contribution margins per hour of OR time usage) and allocative (inefficiency of OR time usage) OR efficiency have concentrated mostly on first case delays and start time tardiness.4–11 The approaches based on ‘‘knife to
Conflict of interest: The authors acknowledge no conflict of interest in the submission. Address for correspondence: Dr. Suvitesh Luthra FRCS(CTh), Division of Cardiac Surgery, Corrigan Minehan Heart Center, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114-2696, USA. Fax: þ 1 617 7265804; e-mail: [email protected]
skin’’ fail to address the dissipation of surgical time during the middle and later parts of the OR cardiac surgical pathway. Few validated quantifiable key performance indicators of OR utilization efficiency in cardiac surgery have been previously described.12–17 The aims of this study were to 1. to determine knife to skin time as a correlate for OR efficiency in cardiac surgery 2. determine the impact of procedure time on OR efficiency in cardiac surgery This study was based at a large teaching hospital and looked at transition times along the OR cardiac surgical pathway of Index of Operational Efficiency (InOE) as an OR audit tool in cardiac surgery. In addition, we discuss methods and strategies to improve efficiency of the pathway. METHODS Data were collected from the hospital SQLserver database (ONCALL, Massachusetts General Hospital
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LUTHRA ET AL. ‘‘KNIFE TO SKIN’’ TIME IS A POOR MARKER OF OR UTILIZATION
Laboratory of Computer Science, Boston) from May till October 2013. Institutional review board approval was not sought as study was part of evaluation for service improvement rather than an evaluation of patient outcomes. Approval was, however, taken from the Head of department for information required from the SQL server database which is a nonclinical OR database. No patient identifiable clinical information was sought or used in the database. We looked only at scheduled coronary artery bypass grafting (CABG), aortic valve replacements (AVR), mitral valve replacement (MVR), aortic surgery, and other miscellaneous cases. Our definitions of the indices are based on considerations of total OR time utilized, allocated OR time (OR block time for the day/intended procedures per block) and other times along the pathway. We used the following base formulaeIndex of Operational Efficiency InOEð%Þ ¼ 100 ðtotal OR time allocated OR time Þ ðOR block time=intended procedures per block Þ 100
surgical time 100 total OR time surgical Index of Operational Efficiency Surgical Ef f iciency ¼
sInOEð%Þ ¼ 100 ðsurgical time allocated OR time Þ ðOR block time=intended procedures per block Þ 100
Our calculations are based on a single eight hour OR block. Any work outside the normal working shift hours incurs unscheduled cost increases in the manpower component of the otherwise fixed operational costing as extra overtime payments. It was based on the assumption that two cardiac cases should ideally be done in a single OR block with four hours per case in a typical OR day.
J CARD SURG 2015;30:477–487
The following calculations were used (all times in minutes). Index of Operational Efficiency InOE (%) ¼ 100 {(total OR time 240) 100}/240. Surgical Index of Operational Efficiency sInOE (%) ¼ 100 {(total OR time procedure time) 100}/240 Cases were not risk stratified. The transfer in/out, skin incision, and skin closure times as recorded in the database for all the cases for this period were analyzed. Times in minutes were calculated for induction of anesthesia, knife to skin time, transfer in and out and the actual procedure. A definition of these times and points of transition in the pathway is given in Figure 1 and Figure 2. Surgeon idling time was defined as time from patient coming to OR to knife to skin (Table 2A). Index of Operational Efficiency (InOE) and surgical Index of Operational Efficiency expressed as a percentage were calculated from the formula given below (Tables 3 and 4, Figs. 3 and 4). Pearson’s correlation coefficients were calculated (SPSS v16.0, IBM, Armonk, NY, USA) for InOE and sInOE values with regard to various times in the operational pathway to study the relationship between various factors (Table 1, Tables 3 and 4A, Figs. 5–8). We further analyzed the team dynamics to study if this had a significant impact on OR efficiency (Tables 5 and 6A). A linear regression analysis was performed to further evaluate these parameters. The goodness of fit of the regression was estimated from regression curve plots for InOE relative to the transition times on the OR pathway. Knife to skin time, procedure time, transfer time, and surgeon idling time were expressed as mean standard deviation and p-values
477
ACQUIRED CARDIOVASCULAR DISEASE ORIGINAL ARTICLE _____________________________________________________________
‘‘Knife to Skin‘‘ Time Is a Poor Marker of Operating Room Utilization and Efficiency in Cardiac Surgery Suvitesh Luthra, F.R.C.S.(CTh).,* Omar Ramady, M.B.B.S.,* Mary Monge, M.B.B.S.,* Michael G. Fitzsimons, M.D.,y Terry R. Kaleta,* and Thoralf M. Sundt, M.D.* *Division of Cardiac Surgery, Massachusetts General Hospital, Boston, Massachusetts; and yDivision of Cardiac Anesthesia, Massachusetts General Hospital, Boston, Massachusetts ABSTRACT Background: Markers of operation room (OR) efficiency in cardiac surgery are focused on ‘‘knife to skin’’ and ‘‘start time tardiness.’’ These do not evaluate the middle and later parts of the cardiac surgical pathway. The purpose of this analysis was to evaluate knife to skin time as an efficiency marker in cardiac surgery. Methods: We looked at knife to skin time, procedure time, and transfer times in the cardiac operational pathway for their correlation with predefined indices of operational efficiency (Index of Operation Efficiency - InOE, Surgical Index of Operational Efficiency - sInOE). A regression analysis was performed to test the goodness of fit of the regression curves estimated for InOE relative to the times on the operational pathway. Results: The mean knife to skin time was 90.6 W 13 minutes (23% of total OR time). The mean procedure time was 282 W 123 minutes (71% of total OR time). Utilization efficiencies were highest for aortic valve replacement and coronary artery bypass grafting and least for complex aortic procedures. There were no significant procedure-specific or team-specific differences for standard procedures. Procedure times correlated the strongest with InOE (r = S0.98, p < 0.01). Compared to procedure times, knife to skin is not as strong an indicator of efficiency. A statistically significant linear dependence on InOE was observed with ‘‘procedure times’’ only. Conclusions: Procedure times are a better marker of OR efficiency than knife to skin in cardiac cases. Strategies to increase OR utilization and efficiency should address procedure times in addition to knife to skin times. doi: 10.1111/jocs.12528 (J Card Surg 2015;30:477–487) Cardiac surgery is a complex pathway involving coordination of multiple steps and team members. The operational costs need to be balanced against the fixed costs of resources and manpower utilization. For most cardiac surgery cases, resource utilization in terms of materials and equipment used is standard and predictable. Manpower resource utilization and time remains an important variable leading to cost escalation, over runs, and inefficiency in the operation room (OR).1–3 Surgical time utilization remains central to OR efficiency. Studies of both technical (based on contribution margins per hour of OR time usage) and allocative (inefficiency of OR time usage) OR efficiency have concentrated mostly on first case delays and start time tardiness.4–11 The approaches based on ‘‘knife to
Conflict of interest: The authors acknowledge no conflict of interest in the submission. Address for correspondence: Dr. Suvitesh Luthra FRCS(CTh), Division of Cardiac Surgery, Corrigan Minehan Heart Center, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114-2696, USA. Fax: þ 1 617 7265804; e-mail: [email protected]
skin’’ fail to address the dissipation of surgical time during the middle and later parts of the OR cardiac surgical pathway. Few validated quantifiable key performance indicators of OR utilization efficiency in cardiac surgery have been previously described.12–17 The aims of this study were to 1. to determine knife to skin time as a correlate for OR efficiency in cardiac surgery 2. determine the impact of procedure time on OR efficiency in cardiac surgery This study was based at a large teaching hospital and looked at transition times along the OR cardiac surgical pathway of Index of Operational Efficiency (InOE) as an OR audit tool in cardiac surgery. In addition, we discuss methods and strategies to improve efficiency of the pathway. METHODS Data were collected from the hospital SQLserver database (ONCALL, Massachusetts General Hospital
478
LUTHRA ET AL. ‘‘KNIFE TO SKIN’’ TIME IS A POOR MARKER OF OR UTILIZATION
Laboratory of Computer Science, Boston) from May till October 2013. Institutional review board approval was not sought as study was part of evaluation for service improvement rather than an evaluation of patient outcomes. Approval was, however, taken from the Head of department for information required from the SQL server database which is a nonclinical OR database. No patient identifiable clinical information was sought or used in the database. We looked only at scheduled coronary artery bypass grafting (CABG), aortic valve replacements (AVR), mitral valve replacement (MVR), aortic surgery, and other miscellaneous cases. Our definitions of the indices are based on considerations of total OR time utilized, allocated OR time (OR block time for the day/intended procedures per block) and other times along the pathway. We used the following base formulaeIndex of Operational Efficiency InOEð%Þ ¼ 100 ðtotal OR time allocated OR time Þ ðOR block time=intended procedures per block Þ 100
surgical time 100 total OR time surgical Index of Operational Efficiency Surgical Ef f iciency ¼
sInOEð%Þ ¼ 100 ðsurgical time allocated OR time Þ ðOR block time=intended procedures per block Þ 100
Our calculations are based on a single eight hour OR block. Any work outside the normal working shift hours incurs unscheduled cost increases in the manpower component of the otherwise fixed operational costing as extra overtime payments. It was based on the assumption that two cardiac cases should ideally be done in a single OR block with four hours per case in a typical OR day.
J CARD SURG 2015;30:477–487
The following calculations were used (all times in minutes). Index of Operational Efficiency InOE (%) ¼ 100 {(total OR time 240) 100}/240. Surgical Index of Operational Efficiency sInOE (%) ¼ 100 {(total OR time procedure time) 100}/240 Cases were not risk stratified. The transfer in/out, skin incision, and skin closure times as recorded in the database for all the cases for this period were analyzed. Times in minutes were calculated for induction of anesthesia, knife to skin time, transfer in and out and the actual procedure. A definition of these times and points of transition in the pathway is given in Figure 1 and Figure 2. Surgeon idling time was defined as time from patient coming to OR to knife to skin (Table 2A). Index of Operational Efficiency (InOE) and surgical Index of Operational Efficiency expressed as a percentage were calculated from the formula given below (Tables 3 and 4, Figs. 3 and 4). Pearson’s correlation coefficients were calculated (SPSS v16.0, IBM, Armonk, NY, USA) for InOE and sInOE values with regard to various times in the operational pathway to study the relationship between various factors (Table 1, Tables 3 and 4A, Figs. 5–8). We further analyzed the team dynamics to study if this had a significant impact on OR efficiency (Tables 5 and 6A). A linear regression analysis was performed to further evaluate these parameters. The goodness of fit of the regression was estimated from regression curve plots for InOE relative to the transition times on the OR pathway. Knife to skin time, procedure time, transfer time, and surgeon idling time were expressed as mean standard deviation and p-values
