Background Creating highly efficient operating room (OR) protocols for total joint arthroplasty (TJA) is a challenging and multifactorial process. We evaluated whether spinal anesthesia in a designated block bay (BBSA) would reduce time to incision, improve first case start time and decrease conversion to general anesthesia (GA).
Methods Retrospective cohort study on the first 86 TJA cases with BBSA from April to December 2018, compared with 344 TJA cases with spinal anesthesia performed in the OR (ORSA) during the same period. All TJA cases were included if the anesthetic plan was for spinal anesthesia. Patients were excluded if circumstances delayed start time or time to incision (advanced vascular access, pacemaker interrogation, surgeon availability). Data were extracted and analyzed via a linear mixed effects model to compare time to incision, via a Wilcoxon rank-sum test to compare first case start time, and via a Fisher’s exact test to compare conversion to GA between the groups.
Results In the mixed effect model, the BBSA group time to incision was 5.37 min less than the ORSA group (p=0.018). The BBSA group had improved median first case start time (30.0 min) versus the ORSA group (40.5 min, p<0.0001). There was lower conversion to GA 2/86 (2.33%) in the BBSA group versus 36/344 (10.47%) in the ORSA group (p=0.018). No serious adverse events were noted in either group.
Conclusions BBSA had limited impact on time to incision for TJA, with a small decrease for single OR days and no improvement on OR days with two rooms. BBSA was associated with improved first case start time and decreased rate of conversion to GA. Further research is needed to identify how BBSA affects the efficiency of TJA.
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In order to combat escalating healthcare costs, hospitals and surgeons are under increasing pressure to develop and implement evidence-based protocols to improve efficiency. The operating room (OR) can be one of the largest contributors to a hospital’s financial success and maximizing OR efficiency is essential for maintaining an economically viable institution.1 2 Improving OR efficiency also can increase physician satisfaction and result in improved workforce morale.1
Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are effective clinical interventions with high rates of success in pain reduction and improved quality of life and function in patients with arthritis of the hip and knee.3–5 The number of these procedures is increasing and the amount of reimbursements for these procedures is decreasing; thus improving efficiency is paramount to maintain overall financial viability.6 Institutions have demonstrated improvements in OR efficiency for total joint arthroplasty (TJA) by improving resource analysis, parallel processing, improving communication, and by elimination of silo mentalities.2 7 Often the focus of improving efficiency is on streamlining existing steps; however, the linear structure of patients moving one by one through the day remains unchanged. Parallel processing specifically breaks away from having patients move through the OR in a linear way by changing patient flow rather than simply working to streamline existing steps.8
To evaluate if spinal anesthesia in a designated block bay (BBSA) adjacent to the OR helped to create OR efficiency we asked the following clinical questions: (1) does BBSA adjacent to the OR reduce time to incision for TJA? (2) Does BBSA improve first case start time for TJA? (3) Does BBSA decrease conversion to general anesthesia (GA) for TJA? (4) Does BBSA increase the risk of anesthetic related complications for TJA?
This was a retrospective cohort study at a single academic medical center. After receiving approval from the institutional review board, we identified 455 primary and revision TJA cases with two surgeons (TH, KS) where the anesthetic plan was for spinal anesthesia from April through December 2018. We excluded 25 patients due to circumstances that delayed start time or turnover time (surgeon or OR availability, equipment delays, advanced vascular access, pacemaker interrogation) (figure 1). This left us with a cohort of the first 86 TJA cases with BBSA and these cases were compared with 344 TJA cases with spinal anesthesia performed in the OR (ORSA) during the same period.
At our institution, we have three preoperative bays reserved for regional anesthesia procedures, which we term our “block bays.” This facilitates access to key equipment such as supplies for peripheral nerve blocks and spinal anesthetics, including spinal trays and various sizes of spinal needles. An ultrasound machine is available in the block bay and can be used for the placement of peripheral nerve blocks or to scan the spine and facilitate performance of a difficult spinal anesthetic. In addition, the block bays are staffed by designated preoperative nurses familiar with regional anesthesia procedures who select the equipment needed for regional blocks and spinal anesthetics. All spinal anesthetic procedures are performed by the anesthesiologist overseeing the OR, however there is a faculty anesthesiologist with specialized training and expertize in regional anesthesia available for consultation or to assist with difficult spinal placement. The transport distance from our block bay to the OR is approximately 150 yards. After the spinal is placed, patient monitoring is transitioned to a portable transfer monitor and emergency intravenous medication is available for transport to the OR. Per our institutional standard at the time, isobaric bupivacaine was used for all spinal anesthetic procedures during the study period.
We evaluated time to incision between TJA cases, defined as the time between when the patient leaves the OR to the time the first incision is made for the next TJA case. If a surgeon was using overlapping surgery with two ORs on a day, this was noted. On days with overlapping surgery, the surgeon and the anesthesia team communicated regarding the appropriate anesthesia start time for the second OR. At our institution, first case start time was defined as the time from the planned scheduled first case start to the time of incision and was only evaluated for the first start OR on days with overlapping surgery. Conversion to GA was noted if the spinal was attempted and deemed inadequate for the procedure or attempted and aborted. Additionally, any anesthetic-related complications were recorded and classified as a serious or minor adverse event based on our institutional patient safety network definitions.
Chart review was performed to collect patient demographics including age, gender, body mass index (BMI), and American Society of Anesthesiology (ASA) classification. Data were extracted and analyzed using Stata V.15 (StataCorp 2017). To compare time to incision, a linear mixed effects model using maximum-likelihood estimation with robust SEs and an independent covariance structure was used. Spinal location, one-OR or two-OR days and surgeon were included as fixed effects. We included a random intercept using a cluster variable to indicate an individual OR nested within a surgery date to account for variation within an OR on a given day. Because two-OR days had longer and more variable time to incision, residuals were calculated by one-OR or two-OR days to account for heteroscedasticity. A Wilcoxon rank-sum test was used to compare first case start time. Fisher’s exact test was used to compare the proportion of conversion to GA between the two groups.
The mean age of the population was 64.3 years (SD 11.8), 37.5% of patients were men, the mean BMI was 31.1 (SD 6.5), and the mean ASA classification was 2.37 (SD 0.54). A majority of the cases were primary TJA (90.2%) versus revision TJA (9.8%). The BBSA group had a lower proportion of primary THA 27/86 (31.4%) than the ORSA group 173/344 (50.3%; p=0.002), and the BBSA group had a higher proportion of primary TKA 47/86 (54.7%) than the ORSA group 141/344 (41.0%; p=0.02). There was no difference noted in the BBSA versus the ORSA groups in terms of age, sex, BMI, or ASA classification (table 1).
Accounting for the factors in the mixed effects model, the time to incision in the BBSA group was 5.37 min less than in the ORSA group (p=0.018). The unadjusted mean time to incision time in the BBSA spinal was 73.5 min (SD 12.5), versus 84.9 min (SD 15.2) in the ORSA group. On single OR days, the unadjusted mean time to incision in the BBSA group was approximately 6 min less than in the ORSA group, but there was only a 1.2 min difference in mean time to incision on days where a surgeon used overlapping surgery with two ORs (table 2).
Our mean OR time was 123.7 min. On one room OR days our mean cases per day was 2.2 cases and on two room OR days our mean cases per day was 4.9 cases. The BBSA group had improved median first case start time at 30.0 min versus 40.5 min in the ORSA group (p<0.0001) (figure 2). There was lower conversion to GA in the BBSA group (2/86, 2.33%) compared with the ORSA group (36/344, 10.47%) (p=0.018).
No serious adverse events were noted in either group. There were three minor adverse events in the BBSA group and three minor adverse events in the ORSA group (table 3).
Creating efficient OR protocols for TJA is an important but challenging and multifactorial process. Parallel processing changes the paradigm of focusing on streamlining existing steps. By breaking away from the linear patient flow, we shifted spinal anesthesia to our block bays. We evaluated this process to determine whether BBSA would reduce time to incision, improve first case start time and decrease conversion to GA, and affect patient safety.
We found a small decrease in turnover time in the BBSA group, which is similar to other studies that evaluated parallel processing to create OR efficiency. Friedman et al evaluated patients undergoing hernia repairs, and shifted local anesthesia to be given outside of the OR prior to the start of surgery.8 They found decreased turnover time by using this similar form of parallel processing. Brown et al evaluated parallel processing by extracting data from patients who underwent upper extremity surgical procedures and modeled the effect of regional anesthesia within and outside the OR.9 They reported reduced total OR time and an increase in the number of surgeries performed in a day.
It was noted in our subgroup analysis that the reduction in time to incision occurred when surgeons were not using OR’s in the same day with overlapping surgical protocols. The practice of overlapping surgery in TJA has been shown to have no effect on 90-day rates of complications, or readmission or reoperation rates when compared with non-overlapping procedures.10 The surgeons in this study only used overlapping surgery, not concurrent surgery, for TJA.11 Zhang et al evaluated their experience with overlapping surgery in the ambulatory orthopedic setting and found no effect on procedure time or total OR time; however, they did not evaluate turnover times.12 Our institution is still using BBSA on overlapping surgery days even if time to incision was not improved, as the advantages in improved first case start time and decreased conversion to GA persist and this allows for a more consistent workflow for TJA. Successfully navigating the timing and stresses of overlapping surgery for TJA is dependent of consistent start times and times to incision for subsequent cases. The TJA surgeons involved with this study all strongly supported the implementation and expansion of the BBSA workflows as the small improvements in start time and time to incision can help to mitigate these stresses and to potentially allow for volume growth and improved time to teach.
Spinal anesthesia is commonly used for TJA due to resultant muscle relaxation without the need for advanced airway support and it is potentially superior in terms of morbidity and mortality.13 14 However, some controversy still exists as other more modern anesthetic protocols challenge the benefits of spinal anesthesia for TJA.15–18 It has been shown that failed spinal anesthesia and conversion to GA for TJA results in longer in OR times.19 We found decreased conversion to GA in the BBSA; however, the documentation did not specifically state the reason for conversion. We suspect that the decreased rate of conversion in the BBSA is related to more immediate access to an attending regional anesthesiologist and regional anesthesia fellow who are available to assist with difficult spinal procedures, immediate access to various sizes and types of spinal needles, ultrasound machines, and skilled block nurses to assist in positioning. It may also be related to decreased sense of pressure to complete the neuraxial procedure outside of the OR and increased time for onset of spinal anesthesia prior to surgical incision.
Many other studies have shown spinal anesthesia for TJA to be safe with low rates of adverse events.13 14 20–22 This supports our finding of minimal adverse events in the BBSA and ORSA groups, and no serious adverse events. It is important to clearly state that after the spinal is placed in the BBSA patients, patient monitoring is transitioned to a portable transfer monitor and emergency intravenous medication is available for transport to the OR.
When we began using the BBSA workflow at our institution, the attending anesthesiologist assigned to the TJA rooms each day was able to opt out of BBSA and perform ORSA instead based on their own comfort and willingness to participate in a new spinal anesthesia workflow for our institution. Reasons for reluctance to participate included concerns about (1) management of hemodynamic changes following administration of spinal anesthesia outside of the OR, (2) the added step of transferring vital sign monitors to a transport monitor and to the OR monitors, and (3) the additional effort required to oversee a new workflow in the setting of conflicting clinical demands. Now that the BBSA workflow has become established at our institution, it is used by all anesthesia providers and satisfaction with BBSA has increased due to experience with the infrequent nature of additional hemodynamic management challenges with BBSA, the ready access to regional anesthesiology experts and equipment in the block bay to assist with challenging spinal anesthetics, the perception of less time pressure for performing the neuraxial procedure, and the potential benefit of increased time for onset of spinal anesthesia prior to surgical incision. We have since expanded our use of BBSA for TJA performed using mepivacaine spinal anesthesia and are working to establish a BBSA workflow at our ambulatory surgical center.
This study has a number of limitations. This was a single academic institution’s experience and the results may not be broadly generalizable, as the processes we developed may not be feasible for other hospitals with variable volume, resources, and throughput. Our institution already had a block bay staffed with nursing so additional resources were not required. However, other institutions should consider their resources and the costs associated prior to engaging in parallel processing strategies. In addition, this was a retrospective cohort study leading to the possibility of selection bias. However, this is a true representation of the first 86 TJA cases performed with BBSA. This data capture the initiation of a new workflow for all members of the perioperative team and this may have limited the magnitude of the potential time efficiency benefit of BBSA. The decision made each day by the attending anesthesiologist assigned to the TJA rooms to perform BBSA or ORSA was a consistent choice for an entire day, but this may have introduced selection bias based on anesthesiologist. In the block bay the regional anesthesiologist was available to assist with difficult spinal placements but we were unable to track how often this resource was used. As many institutions may not have a dedicated regional anesthesiologist, this must be considered in the context of our results.
BBSA adjacent to the OR may have limited impact on time to incision. We observed a small improvement in time to incision on single OR days and no improvement on OR days when overlapping or two room surgery protocols were used. We also found improved first case start time and decreased rate of conversion to GA for TJA with BBSA. Given the limited nature of this retrospective analysis, further research is needed to evaluate the potential benefits of this parallel processing strategy on the efficiency of TJA procedures.
The authors would like to thank Rebecca Wetzel for her assistance in editing and formatting the manuscript.
Contributors All authors have made substantial contributions to the conception and design of the work being submitted. SZ, AS specifically contributed the majority of the data acquisition, RK, AJJ and RI specifically contributed the majority of the interpretation of the data for the work. All authors have contributed to drafting the work, revising critically have given final approval of the version to be published. Additionally all authors are in agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Oregon Health and Science University IRB - STUDY00019793: Block Bay Spinal Anesthesia for Total Joint Arthroplasty: A Retrospective Study of Efficiency and Safety.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. IRB approval will be sought to transfer data on a case-by-case basis, as the originally approved protocol did not cover data transfer to outside institutions.