Analysis of Operating Room Efficiency During Robot-Assisted Urologic Surgeries Utilizing Fixed (Nonprocedural) Operative Times

Abstract

Objective:

To analyze operating room (OR) efficiency by evaluating fixed OR times for three common urologic robot-assisted procedures.

Methods:

Over a 24-month period, we prospectively collected intraoperative data for 635 consecutive robot-assisted surgeries. Fixed (nonprocedural) OR times were evaluated for robot-assisted partial nephrectomy (RAPN) (n = 146), robot-assisted radical cystectomy (RARC) (n = 77), and robot-assisted radical prostatectomy (RARP) (n = 412). Fixed OR times were defined as nonprocedural time in the OR, including in-room time to anesthesia release time (IRAT), anesthesia release to cut time (ARCT), in-room time to cut time (IRCT; IRAT+ARCT), and close time to wheels out time (CTWO). The effects of operation time of day and the number of anesthesia personnel (AP) present in procedure on fixed OR times were also analyzed.

Results:

Fixed OR times occupied 15.1% (IQR: 12.9%–17.1%) (RARC), 26.6% (22.9%–30.8%) (RAPN), and 20.1% (17.4%–23.1%) (RARP) of total OR time. Time of day did not have a negative effect on fixed OR times for robotic urologic surgeries. Median AP count was highest for RARC (median: 3 and range: 1–7). We did not find any association between AP count and fixed OR times for any of the procedures (p ≥ 0.19).

Conclusions:

Fixed OR times made up a significant percentage of total OR time for robot-assisted procedures and should be incorporated into OR efficiency analyses. The number of AP per case and time of day of procedure did not negatively impact fixed OR times in urologic robotic surgeries.

Introduction

Robot-assisted procedure has become increasingly common within urologic practice. The complex machinery involved in robotic procedure requires specialized multidisciplinary teams to provide for patient safety as well as for increased operating room (OR) efficiency.¹ The necessity of managing shift rosters to ensure experienced robotically trained personnel are available for robot-assisted procedures to maintain patient safety and efficiency has also been reported.² OR efficiency is often studied with the goal of decreasing hospital costs and increasing productivity.^1,3 OR efficiency is impacted by all personnel involved in the procedure, including surgeons, trainees, anesthesia providers, nursing, and other OR personnel.⁴ OR efficiency may also be affected by case complexity and patient-related factors.

Previous robotic efficiency studies have broken procedures into time points, but these times were in relation to the robotic machinery (docking, instrumentation, etc.).² Other articles have evaluated OR efficiencies by studying surgeon operating time, console time, first case start time, and flow disruptions.^2,5

Surgeon operating time (cut to close) may vary by procedure performed, case complexity, patient factors, surgeon experience, and OR personnel experience/familiarity. Little is known about the contribution of nonprocedural OR time on overall case times and OR efficiency. We defined nonprocedural OR time as “fixed OR times,” consisting of in-room time to anesthesia release time (IRAT), anesthesia release to cut time (ARCT), and close to wheels out time (CTWO). The purpose of this study was to evaluate these fixed OR times as they relate to three commonly performed robot-assisted surgeries in urology (prostatectomy, radical cystectomy, and partial nephrectomy), as well as the impact of time of day of procedure and the number of frontline anesthesia personnel (AP) present per case on these fixed OR times.

Methods

Study cohort

Over a 24-month period (2019–2020), intraoperative data on 635 consecutive robot-assisted urologic procedures at a single academic medical center was prospectively collected. We evaluated three common urologic robot-assisted procedures: robot-assisted partial nephrectomy (RAPN), robot-assisted radical cystectomy (RARC), and robot-assisted radical prostatectomy (RARP). The 146 RAPN procedures were completed by two surgeons, both of which are fellowship trained. The 77 RARC procedures were completed by two surgeons, one of which is fellowship trained. The 412 RARP procedures were completed by four surgeons, three of which are fellowship trained. The Da Vinci Xi surgical system (Intuitive Surgical Company Sunnyvale, CA) was utilized for all procedures. Information regarding the number of AP per procedure was also collected. This study was defined as exempt by the Mayo Clinic Institutional Review Board (21-10068).

Variable definitions

Fixed (nonprocedural) OR time was defined as IRAT, ARCT, in-room time to cut time (IRCT) (a combination of IRAT and ARCT), and close time to wheels out time (CTWO) (Fig. 1). IRAT consisted of safe patient delivery to operating table, patient intubation, and anesthesia line placement. ARCT was made up of patient positioning and sterilization of the operative field. CTWO involved awaking the patient from anesthesia and stabilization before transport.

FIG. 1.

Timeline illustrating fixed (nonprocedural) and variable (procedural) operating time points over the span of total OR time. OR = operating room. Color images are available online.

The primary outcome of this study was percent of total OR time occupied by fixed OR times, which was calculated by adding IRAT, ARCT, and CTWO, dividing the resulting sum by total OR time, and then multiplying the quantity by 100. Secondary outcomes included impact of time of day and number of AP on fixed OR times. To assess time of day, cases were stratified by start time as either morning (incision before 12 PM) or afternoon (incision at or after 12 PM) cases. RARC was excluded from the time-of-day portion of the analysis owing to all RARC procedures being performed in the morning.

We compared the number of AP between RAPN, RARC, and RARP and evaluated the impact of AP count per case on the fixed OR times. AP included front-line anesthesia staff such as resident trainees and certified registered nurse anesthetists (CRNA). We collected the number of AP involved with each procedure. Attending anesthesiologists (M.D. or D.O.) were not included in these AP counts. Within each procedure, we compared surgeries with two or more AP involved per case vs surgeries with less than two AP per case.

Statistical analysis

Continuous variables were described with the median and interquartile range (IQR) along with box plots. Summaries of categorical variables included the number and percentage of procedures. The Wilcoxon rank sum test was used to compare fixed OR times between procedures that started in the morning and procedures that started after noon. We used linear regression models in sensitivity analyses for evaluating the association of time of day (afternoon vs morning) with fixed OR times. Covariates in the multivariable models included AP count and fixed OR times that occurred before the fixed OR time interval of interest. We used single variable and multivariable linear regression models to evaluate the relationship between the number of AP and fixed OR times where multivariable models included time of day (morning or afternoon) and fixed OR times that occurred before the time interval of interest as covariates.

Coefficients and corresponding 95% confidence intervals (CIs) from the linear regression models were reported. Two-sided p-values <0.05 were considered statistically significant without adjustment for multiple testing. The R version 3.6.2 (R Foundation for Statistical Computing, Vienna, Austria) was utilized for statistical analysis and creation of graphics.

Results

Over the course of the consecutive 24-month period, 635 robot-assisted procedures were evaluated (77 RARC, 146 RAPN, and 412 RARP). Median total procedure time was 473 minutes (IQR: 415–779) for RARC, 273 minutes (244–308) for RAPN, and 271 minutes (247–297) for RARP.

Table 1 shows a descriptive summary of fixed OR times for each of the three robot-assisted procedures. The median percentage of total OR time occupied by all fixed OR times was 15.1% for RARC (IQR: 12.9%–17.1%), 26.6% for RAPN (22.9%–30.8%), and 20.1% for RARP (17.4%–23.1%).

Table 1.

Fixed (Nonprocedural) Operating Room Times for Robot-Assisted Procedures

OR time	RARC (N = 77)		RAPN (N = 146)		RARP (N = 412)
OR time	n	Median (IQR)	n	Median (IQR)	n	Median (IQR)
Fixed, %^a	77	15.1 (12.9, 17.1)	145	26.6 (22.9, 30.8)	409	20.1 (17.4, 23.1)
IRAT, minutes	77	26 (20, 33)	146	20 (16, 25)	411	15 (12, 19)
IRAT, %^a	77	5.5 (4.4, 6.7)	146	7.3 (5.5, 9.4)	411	5.6 (4.2, 7.0)
ARCT, minutes	77	30 (25, 40)	144	40 (36, 46)	409	29 (24, 34)
ARCT, %^a	77	6.2 (5.4, 8.2)	144	15.1 (11.5, 17.6)	409	10.7 (8.7, 12.8)
IRCT, minutes	77	60 (51, 67)	146	62 (56, 68)	411	45 (40, 50)
IRCT, %^a	77	12.8 (10.6, 14.5)	146	22.3 (19.2, 26.1)	411	16.6 (14.3, 19.1)
CTWO, minutes	77	11 (8, 15)	145	11 (7, 15)	409	9 (7, 12)
CTWO, %^a	77	2.5 (1.5, 3.3)	145	3.9 (2.6, 5.4)	409	3.5 (2.4, 4.5)

Percentage of total OR time (in-room time to wheels out time).

ARCT = anesthesia release to cut time, CTWO = close time to wheels out time; IQR = interquartile range; IRAT = in-room time to anesthesia release time; IRCT = in-room time to cut time; OR = operating room; RAPN = robot-assisted partial nephrectomy; RARC = robot-assisted radical cystectomy; RARP = robot-assisted radical prostatectomy.

Median IRAT time was longest for RARC (26 minutes, IQR: 20–33) and shortest for RARP (15 minutes, 12–19), whereas RAPN was in the middle (20 minutes, 16–25) (Fig. 2A). Median ARCT was longest for RAPN (40 minutes, 36–46), shortest for RARP (29 minutes, 24–34), and RARC was in between (30 minutes, 25–40) (Fig. 2B). IRCT median time was longest for RAPN (62 minutes, 56–68) and shortest for RARP (45 minutes, 40–50), with RARC between the two (60 minutes, 51–67) (Fig. 2C). CTWO median time was the same for both RARC (11 minutes, 8–15) and RAPN (11 minutes, 7–15); it was shortest for RARP (9 minutes, 7–12) (Fig. 2D).

FIG. 2.

Box plots of fixed (nonprocedural) OR times for three robot-assisted procedures. Fixed OR times included IRAT (A), ARCT (B), IRCT (C), and CTWO (D). ARCT = anesthesia release to cut time; CTWO = close time to wheels out time; IRAT = in-room time to anesthesia release time; IRCT = in-room time to cut time; RAPN = robot-assisted partial nephrectomy; RARC = robot-assisted radical cystectomy; RARP = robot-assisted radical prostatectomy.

Most operations occurred in the morning: 100% (77/77) of RARCs, 53% (77/146) of RAPNs, and 66% (271/412) of RARPs. Table 2 compares morning vs afternoon procedures for both RAPN and RARP and their distributions are displayed graphically in Figures 3A–D. RARCs were excluded from this analysis because they were only performed in the morning because of their longer OR times. We did not find any statistically significant association of time of day with fixed OR times during RAPN (all differences in median fixed OR times ≤2 minutes, all Wilcoxon rank sum test p ≥ 0.097) (Fig. 3A–D).

FIG. 3.

Box plots of fixed (nonprocedural) OR times during morning (AM) and afternoon (PM) RAPN and RARP. Fixed OR times included IRAT (A), ARCT (B), IRCT (C), and CTWO (D). RARC was not included because no procedure started in the afternoon.

Table 2.

Comparison of Fixed (Nonprocedural) Operating Room Times Between Procedures That Started in the Morning and Procedures That Started in the Afternoon

Procedure	OR time	Morning procedures		Afternoon procedures		p ^a
Procedure	OR time	n	Median (IQR)	n	Median (IQR)	p ^a
RAPN	Fixed, %^b	77	27.2 (22.7, 31.4)	68	26.4 (23.8, 30.2)	0.40
	IRAT, minutes	77	21 (16, 26)	69	19 (15, 23)	0.097
	IRAT, %^b	77	7.9 (5.8, 9.7)	69	6.7 (5.3, 8.7)	0.065
	ARCT, minutes	76	40 (36, 47)	68	41 (36, 46)	0.94
	ARCT, %^b	76	15.2 (11.4, 17.8)	68	14.9 (11.6, 17.3)	0.54
	IRCT, minutes	77	62 (56, 68)	69	62 (54, 66)	0.24
	IRCT, %^b	77	22.8 (19.6, 27.0)	69	21.2 (19.2, 25.4)	0.14
	CTWO, minutes	77	11 (8, 14)	68	11 (6, 16)	0.57
	CTWO, %^b	77	4.2 (2.7, 5.1)	68	3.9 (2.3, 5.8)	0.79
RARP	Fixed, %^b	268	20.0 (17.4, 23.1)	141	20.2 (17.6, 22.9)	0.61
	IRAT, minutes	270	15 (11, 19)	141	14 (12, 20)	0.80
	IRAT, %^b	270	5.6 (4.2, 6.8)	141	5.7 (4.4, 7.2)	0.26
	ARCT, minutes	269	30 (25, 35)	140	28 (23, 33)	0.028
	ARCT, %^b	269	10.7 (8.7, 13.0)	140	10.7 (8.8, 12.4)	0.75
	IRCT, minutes	270	45 (41, 50)	141	43 (38, 49)	0.032
	IRCT, %^b	270	16.6 (14.2, 19.2)	141	16.5 (14.5, 19.0)	0.74
	CTWO, minutes	268	9 (7, 12)	141	9 (7, 12)	0.56
	CTWO, %^b	268	3.5 (2.3, 4.4)	141	3.6 (2.4, 4.5)	0.57

Wilcoxon rank sum test.

Percentage of total OR time (in-room time to wheels out time).

During RARP, median ARCT and IRCT were 2 minutes faster in the afternoon compared to procedures that started in the morning (difference in median ARCT and IRCT = −2 minutes, Wilcoxon rank sum test p = 0.028 and 0.032, respectively). For RARP, we did not find any statistically significant association of time of day with the percentage of total time occupied by fixed OR time, IRAT, or CTWO (all differences in fixed OR times ≤1 minute, all Wilcoxon rank sum test p ≥ 0.56). Multivariable linear regression models were done as a sensitivity analysis and the results were consistent with the results in Table 2 (Supplementary Table S1).

RARC had the highest median AP count (median: 3, range: 1–7). RAPN and RARP both had a median AP count of 2 (range: 1–5). Table 3 describes the number of AP involved in the three procedures. In an exploratory analysis, we did not find any evidence of an association of AP count with fixed OR times during RARC (all p ≥ 0.21), RAPN (all p ≥ 0.19), or RARC (all p ≥ 0.33) (Supplementary Table S2).

Table 3.

Number of Anesthesia Personnel During Robot-Assisted Procedures

	RARC (N = 77)	RAPN (N = 146)	RARP (N = 412)
AP count
Median (p0, p25, p75, p100)	3 (1, 2, 4, 7)	2 (1, 2, 3, 5)	2 (1, 2, 3, 5)
Distribution, n (%)
1	6 (7.8)	27 (18.5)	71 (17.2)
2	21 (27.3)	74 (50.7)	203 (49.3)
3	28 (36.4)	41 (28.1)	129 (31.3)
4	17 (22.1)	3 (2.1)	6 (1.5)
5 or more	5 (6.5)	1 (0.7)	3 (0.7)

p0 = minimum, p25 = 25th percentile, p75 = 75th percentile, p100 = maximum.

AP = anesthesia personnel.

Discussion

When evaluating robot-assisted procedure by fixed and variable OR times, we found that the fixed times occupied a significant portion of the operation time (as much as 49% for some procedures). These observations serve to highlight the importance of assessing and analyzing nonsurgical time in the OR when seeking to optimize OR efficiency. Kozminski et al. found that robotic setup time (defined as the time from procedure start to console start) was shortest for prostatectomies and longest for their “other” category, which included cystectomies and pyeloplasties, whereas renal surgeries were in the middle.⁶

They found robotic setup time to be variable for procedure type as well as patient gender, thus confirming our inclusion of that step in variable (procedural) OR time.⁶ We looked at fixed OR times because they can be generalized across institutions and found that all fixed OR times were shortest for RARP. RARP was one of the first robot-assisted procedures to be performed across all surgical specialties.⁷ Of the three procedures we evaluated, it is also the most commonly performed procedure at our institution. Each of these factors may have had a role in it being the most efficient procedure evaluated.

Two recent studies divided total OR time into subcategories, focused specifically on the robotic machinery (prerobot, robot docking, surgical intervention, and procedure completion).^2,5 They analyzed OR efficiency through studying flow disruptions (communication, coordination, equipment, and training). Jain et al. examined RARP, robotic sacrocolpopexies, and robotic nephrectomies and evaluated external factors, environment, patient factors, surgeon decision making, instrument changes, and psychomotor error that affected OR time. Catchpole et al. evaluated robot-assisted procedures within multiple specialties (Nephrology, Urology, Cardiac procedure, and Gynecology). Jain et al. reported RARP to have a mean total OR time of 283 minutes (95% CI of the mean: 258–307),⁵ which is consistent with the median total OR time of 271 minutes (IQR: 247–297) reported in this study.

Both Catchpole et al. and Jain et al. found the majority of flow disruptions occurred during the surgical intervention phase. Catchpole et al. found that coordination and equipment were the most common flow disruptions to OR efficiency. Jain et al. found that the most common flow disruptions to OR efficiency were training, equipment, and instrument changes. In their study the prerobot phase was mostly disrupted by coordination issues, whereas the robot docking phase was mostly affected by equipment disruptions. The surgeon console phase and the robot undocking and closure phase were affected most by equipment and training disruptions.⁵

We found that median ARCT times were ∼10 minutes longer for RAPN than RARC and RARP, which may be explained by patient positioning. RAPN utilizes the complex modified flank position, whereas both RARC and RARP utilize the relatively easier dorsal lithotomy position.

IRCT made up a significant portion of total OR time (RARC: 60/473 minutes, RAPN: 62/273 minutes, and RARP: 45/271 minutes). This time was nonprocedural time in the OR before surgeon cut time. This time consisted of IRAT (patient delivery to operating table, patient intubation, and anesthesia line placement) and ARCT (surgical positioning and sterilization). It is essential that this period of time is performed as efficiently as possible to avoid prolonged patient anesthesia. Jain et al. reported RARP's prerobot phase (in room to abdominal insufflation) to be just under 50 minutes.⁵ This was slightly longer than what we found; however, they included cut time and abdominal insufflation in this phase, whereas we stopped our time point at cut time.

The number of AP involved in the robot-assisted surgeries was not associated with fixed OR times for any of the surgeries in this analysis. The cost-effectiveness of various AP has been reported by Hogan et al.⁸ Their study discussed the efficiency of CRNAs vs anesthesiologists, whereas our study focused solely on how AP shift changes within a procedure affected duration of fixed OR times. In the study by Jain et al., shift changes could be considered a flow disruption depending on the smoothness of the transition. They found every flow disruption increased the length of the procedure by 2.4 minutes, thus highlighting the importance of experienced staff and clear communication.⁵ Our data do not support the hypothesis that an increased number of AP alters fixed OR times during robotic urologic procedure, suggesting that any impact may be limited to the procedure time itself.

After a review of the literature, we believe we are the first to report on the impact of time of day on OR efficiency for urologic procedures. It has been reported that time of day does not affect postoperative risk in certain cardiothoracic surgeries⁹; however, it does significantly impact complication rates in orthopedic trauma surgeries.¹⁰ We found that median ARCT was ∼2 minutes faster in the afternoon for RARP, as was the median IRCT, which includes ARCT and IRAT. However, IRAT and CTWO were not impacted by the time of day. We are unsure as to why some of the RARP fixed times were faster in the afternoon.

Our study was strengthened by its prospective nature of data collection as well as the subspecialization of our institutions' surgeons and nursing staff performing the procedures. Our data are unique in that there are no other publications on these fixed, nonprocedural, OR times. Our hope is to start a discussion on acceptable duration of fixed time points in robot-assisted urologic procedures to improve efficiency across the field. However, we acknowledge this study was not without limitations. A potentially confounding variable was that the COVID-19 pandemic time frame was included in our study. It was reported that during the pandemic OR nurses were assigned to units other than their own.¹¹ Some of the more experienced nurses may have been moved to a different unit, thereby decreasing efficiency.

Our study also did not analyze any patient demographics that may have caused variations in these fixed OR times, which were not available in the de-identified data set, but could have a significant impact on the efficiency of a procedure. We also did not include turnover time in our analysis. It is possible that, whereas time of day and AP count did not impact our fixed OR times for the robotic surgeries, they may have had an impact on the time between cases. Finally, our data may not be generalizable to other practice settings.

Conclusions

Fixed (nonprocedural) OR times made up a significant portion of total OR time for robot-assisted procedures and should therefore be taken into account when performing OR efficiency analyses. RARP had the shortest fixed OR times of all the procedures evaluated. The number of frontline AP per case did not significantly impact the efficiency of fixed OR time points in robot-assisted urology procedures.

Footnotes

Authors' Contributions

Conception and design: L.E.G., C.H.H., and D.D.T. Administrative support: C.H.H., A.N.A.-Y., and D.D.T. Provision of study materials or patients: C.H.H. and D.D.T. Collection and assembly of data: all authors. Data analysis and interpretation: L.E.G., C.H.H., M.A.W., C.T.B., and D.D.T. Article writing: L.E.G. and D.D.T. Final approval of article: all authors.

Author Disclosure Statement

All authors have no disclosure to report.

Funding Information

No funding was received for this article.

Supplementary Material

Supplementary Table S1

Supplementary Table S2

Abbreviations Used

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Supplementary Material

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