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Decrease in Wrong-Site Peripheral Nerve Block Risk Following Changes to Anesthesia Time-Out Policy
Session: MP-06c
Fri, April 20, 10:15-11:45 am
Plymouth (Shubert Complex), 6th floor

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Decrease in Wrong-Site Peripheral Nerve Block Risk Following Changes to Anesthesia Timeout Policy.


Wrong site peripheral nerve blocks (WSPNB), considered a never-event, continue to occur with alarming frequency with one article reporting a risk of 3.63/10,000 blocks (1). The success of formal timeout processes has been well-documented in reducing the risk of wrong-site surgeries (2). Our institution, where the vast majority of anesthetics are regional, instituted an anesthesia timeout separate from the pre-existing surgical timeout in 2003 (3). Despite this separate anesthesia timeout, WSPNB were still occurring with some frequency.

 Being that wrong site procedures are a state reportable event in New York state, each event required a root-cause analysis. As part of this process, each event required our institution to re-evaluate the policy and implement changes to improve any shortcomings (Figure 1).

 Of these changes the one that seemed to have the most impact was implemented in 2006. At this time, the policy was adjusted in two important ways: the circulating nurse sequestered all of the peripheral nerve block needles, and remained at the bedside after the timeout occurred until the block was initiated. The objectives of these processes are to encourage a team approach to the anesthesia timeout and to minimize time between the timeout and the block (4). The goal of this study was to estimate the association between the augmented anesthesia timeout and the risk of WSPNB.


The QA/PI division of the Anesthesiology Department maintains statistics on anesthetic types through daily quality audits. All WSPNB from January 2003-December 2016 have been reported to the QA/PI division, have had root-cause analyses performed and are required to be reported through the New York State mandatory occurrence reporting system (NYPORTS).

 The risk of WSPNB for all peripheral nerve blocks (PNB) 2003-2016 is presented as a point estimate (frequency per 10,000 blocks) with a 95% Wilson score confidence interval (CI). Relative risks of WSNB (pre-implementation [2003-2006] vs. post-implementation [2007-2016] risks) are presented for upper extremity, lower extremity, and all blocks as point estimates with 95% score CIs. The risk of WSPNB was compared pre- vs. post-implementation for upper extremity, lower extremity, and all blocks using Fisher’s exact tests. Statistical analyses were performed with SAS version 9.4 (SAS Institute, Cary, NC) and the PropCIs package in R software version 3.3.1 (R Foundation for Statistical Computing, Vienna, Austria). The plot was produced using the forestplot package in R software version 3.3.1.


The risk (95% CI) of WSPNB per 10,000 blocks for all PNB types (upper and lower extremity) from 2003-2016 was 0.46 (0.24, 0.92). The risk of WSPNB per 10,000 blocks decreased for all peripheral nerve block types from 1.10 to 0.24 pre- (2003-2006) to post- (2007-2016) policy change, respectively (relative risk [95% CI]: 0.22 [0.06, 0.82]; p = 0.034) (Figure 1). The decrease in risk was more pronounced for lower extremity blocks (relative risk [95% CI]: 0.15 [0.03, 0.69]; p = 0.027) than upper extremity blocks (0.44 [0.05. 4.26]; p = 0.521) (Figure 2).


Our results show that the 2006 update to our anesthesia timeout policy was associated with a decrease in the risk of WSPNB. However, a causal effect cannot be determined given the risk of bias associated with this type of experimental model and our lack of adjustment for potential confounders.

 Policies and systems are intended to prevent human error but our institution recognizes the importance of them to be dynamic. Institutional culture, staff, procedures, regulations and OR environments are ever-changing. To ensure policies continue to be effective, they must continued to be evaluated and be adaptable to such change.

 While a randomized controlled trial comparing different anesthesia timeout methods may not be feasible, adequately adjusted “before-and-after” comparisons are warranted to confirm our findings. We plan to continue to evaluate our policy and account for any factors that may impact how it is performed.


1. Barrington MJ, Uda Y, Pattullo SJ, Sites BD. 2015. Wrong-site regional anesthesia: review and recommendations for prevention? Current Opinion in Anaesthesiology. 28(6): 670-684.

2. Algie CM, Mahar RK, Wasiak J, Batty L, Gruen RL, Mahar PD. 2015. Intervention for reducing wrong-site surgery and invasive clinical procedures (Review). Cochrane Database Syst Rev. 2015 Mar 30;(3):CD009404.

 3. Edmonds CR, Liguori GA, Stanton MA. 2005. Two Cases of a Wrong-Site Peripheral Nerve Block and a Process to Prevent this Complication. Regional Anesthesia and Pain Medicine. 30(1): 99-103.

 4. Stanton MA, Tong-Ngork S, Liguori G, Edmonds CR. 2008. A New Approach to Preanesthetic Site Verification After 2 Cases of Wrong Site Peripheral Nerve Blocks. Regional Anesthesia and Pain Medicine. 33(2): 174-177.

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