Clinical evaluation of intraoperative near misses in laparoscopic rectal cancer surgery

Nathan J Curtis FRCS, FEBS 1,2, Godwin Dennison FRCS 1, Chris SB Brown MSc 3, Peter J Hewett MBBS FRACS 4,

George B Hanna PhD FRCS 2, Andrew RL Stevenson MBBS FRACS 4,5 and Nader K Francis PhD FRCS 1,6

1 Department of General Surgery, Yeovil District Hospital NHS Foundation Trust, Yeovil, UK

2 Department of Surgery and Cancer, Imperial College London, London, UK

3 National Health and Medical Research Council Clinical Trials Centre, University of Sydney, Sydney,

Australia

4 Department of Surgery, University of Adelaide, Adelaide, Australia

4 Faculty of Medical and Biomedical Sciences, University of Queensland, Brisbane, Queensland,

Australia

5 Royal Brisbane and Women’s Hospital, Brisbane, Queensland, Australia

6 Faculty of Science, University of Bath, Bath, UK

ORCID IDs NJC: 0000-0001-5655-6823 GBH: 0000-0003-2897-0140 NKF: 0000-0001-8498-9175

Corresponding author: Prof Nader Francis, nader.francis@ydh.nhs.uk +44 1935 384244

Previous Communication: Oral presentation to the European Association of Endoscopic Surgeons

congress, Seville, Spain, June 2019.

Word Count: 2538 Abstract word count: 250

Running title: Near misses in laparoscopic rectal cancer surgery

Keywords: Adverse events, near miss, laparoscopic, intraoperative, rectal cancer

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Funding: None received for this study. The ALaCaRT trial was supported by grants from the

Colorectal Surgical Society of Australia and New Zealand Foundation and the Australian National

Health and Medical Research Council. The 2D/3D trial was funded by a research grant from the

European Association of Endoscopic Surgeons.

Conflict of interest & disclosure statement: All confirm they hold no conflicts of interest or financial

ties in relation to this manuscript.

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Introduction

Surgical safety is recognised as a key indicator of care quality by most global health organizations.

Over the past decade, the World Health Organisation has undertaken a number of widely

implemented global patient safety initiatives aiming to minimise surgical adverse events (1, 2).

Although these safety checklists and reporting systems incorporate most of the care pathway, the

surgical intervention receives comparatively less attention.

The operating room is reported as the most frequent location for hospital errors (3, 4). In contrast

to high risk industries including those where humans interact with complex systems, the

intraoperative surgical period is not robustly documented with evidence of adverse event under-

reporting and wide variation in practice (5-8).

Advanced laparoscopic surgery is technically challenging with surgical performance likely to account

for observed outcome differences (9-11). Oncological outcomes following laparoscopic total

mesorectal excision (TME) correlate with specimen quality highlighting the need for proficient

performance (12, 13). Technical error in surgery is commonplace including within cases performed

by specialists with apparent successful outcomes and the absence of post-operative morbidity (14,

15). Associated impacts of these events can be highly variable and subject to numerous factors

including luck. Consequences, if any, may range from trivial to significant. Near misses are currently

underreported in surgery (6). This may be attributed to the lack of reliable means to objectively

quantify and report adverse events occurring in the operative environment (16, 17). This potentially

valuable data source could inform preventive steps to avoid future incidents (8).

To assist the promotion and standardisation of intraoperative reporting we previously designed an

adverse event classification (17). This system categorizes intraoperative events with the goal of

reproducing industrial practice where it long been acknowledged that near misses form the base of a

pyramid with serious incidents typically preceded by numerous low impact ones (18). The aim of this

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study was to investigate intraoperative adverse near miss events within advanced laparoscopic

surgery and any associated impact upon clinical outcomes.

Methods

Patients and clinical data

A pooled analysis of case videos and matched clinical data from two completed multicentre

laparoscopic total mesorectal excision (TME) randomized controlled trials - the Australasian

laparoscopic cancer of the rectum trial (ALaCaRT, ACTRN12609000663257) and the 2D/3D

laparoscopic TME trial (ISRCTN59485808) was performed (19-21). Both trials included patients with

rectal adenocarcinoma ≤15cm from the anal verge undergoing elective resection with curative intent

from credentialed surgeons. Open cases (n=235) were excluded as were procedures converted to

open surgery (n=25) and cases with no video available (n=93). To ensure heterogeneity,

abdominoperineal resections were also excluded (n=25). Full methodology, inclusion and exclusion

criteria, ethical approvals, details of video capture and trial results have been reported (19-21).

Error identification

All videos were deidentified, re-coded and analysed by a blinded reviewer with 1500 hours of

laparoscopic surgical video review experience. The observational clinical human reliability analysis

(OCHRA) technique was applied in keeping with previous successfully use in specialist surgeon

laparoscopic rectal cancer surgery studies including two multicentre RCTs and the UK LapCo national

laparoscopic training programme (21-27). Briefly, OCHRA comprises structured continuous analysis

of unedited surgical video to identify intraoperative adverse events which were defined as

“something that was not intended by the surgeon, nor desired by a set of rules or an external

observer, or that led the task outside acceptable limits” (28). Identified events were categorized

using pre-defined lists of generic error descriptions, external error mode, instrument used and any

associated consequence (supplementary tables 2-4). A hierarchical task analysis was used to divide

procedures into surgical task phases based upon the international laparoscopic TME standardisation

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consensus report and prior OCHRA rectal cancer studies (21, 22, 29). In keeping with their primary

endpoint, the ALaCaRT protocol limited video capture to pelvic surgery and so this study focussed on

TME dissection, bowel transection and anastomosis as defined in table 1. Pelvic error location was

divided into seven spatial zones in keeping with previous experience (22) (supplementary table 5). A

patient centred approach was taken with no distinction made between errors enacted by the

specialist surgeon or the assistant. Videos were reviewed using Adobe Premiere Pro CS6® with

timestamping of all identified adverse events (San Jose, CA, USA).

Error severity & near miss analysis

After OCHRA assessment, all identified error events were revisited together with the preceding and

following 30 seconds of footage and additionally categorized using the European Association of

Endoscopic Surgeons (EAES) intraoperative laparoscopic adverse event classification (17). To

maximise objectivity, reproducibility and clinical applicability this system has five grades based on

the principle of therapy required to remedy the identified adverse event (table 2). Near miss events

were defined as EAES grade 1 (minor error with no damage or corrective action required) with EAES

grades 3 and 4 events considered as major intraoperative events. Examples of errors and each EAES

grade are shown in table 2 and supplementary digital content videos 1-6.

Reliability assessment

Test-retest reliability was explored utilising the original analysis performed for the 2D/3D trial. Inter-

rater reliability was explored using scores from a second trained assessor who independently

reviewed all identified adverse events. Reviewers were able to report that previously observed

events did not meet the definition of error. Both were blinded to previously awarded grades but had

access to matched case morbidity and outcome data in keeping with the proposed use of the EAES

classification (17).

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Clinical validity and study endpoints

Clinical validity of near misses formed the primary endpoint of this study and was explored using the

sum of EAES grade 1 errors per case. Perioperative and 30-day morbidity events documented within

the trials were graded using the Clavien-Dindo classification and common terminology criteria for

adverse event reporting (30, 31). Secondary endpoints were clinical (re-operation, anastomotic leak

and length of stay) and histopathological (plane of mesorectal dissection and meeting the primary

ALaCaRT composite endpoint).

Statistical analysis

Data was analysed using SPSS (v24, IBM, NY, USA). EAES grades and case grade 1 error total were

considered as ordinal and scale variables respectively. Reliability was explored using Cohen’s kappa

(κ) with 95% confidence intervals. p<0.05 was considered significant. For categorical clinical data,

analysis included the use of cross tabulation and Fisher’s exact test. Data were analysed for

normality with the Spearman rank correlation test applied to assess the relationship between

continuous variables. Data is displayed as medians and interquartile range unless otherwise

specified. T-Test, Mann-Whitney U and Kruskal-Wallis tests were used to compare averages from

normal and non-normally distributed populations.

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Results

175 laparoscopic TME cases were included. Patient and tumour demographics are shown in

supplementary table 1.

Intraoperative pelvic errors and near misses

A total of 1113 errors events were captured during TME dissection, bowel transection and

anastomotic components of the procedures. All error events were successfully categorized with the

EAES classification (table 2). 698 near miss events (62.7%) were identified in the pelvic task phases

with significant variation in counts observed between included cases (median 3, interquartile range

2-5, range 0-15, p<0.001). Only five cases (2.9%) were error free. There was a stepwise decrease in

event frequency in each additional EAES grade (EAES2 379 (34%), EAES3 33 (3%), EAES4 3 (0.3%),

table 2). One major intraoperative event was observed for every 19.4 near misses (figure 1).

Nature of near misses

OCHRA categorical data for near miss events are displayed in supplementary tables 2-5. Dissection

and instrument errors (67%) were more prevalent than retraction and handling errors of which

‘wrong tissue plane’ (27%), ‘too close to structure’ (11.5%) and ‘overshoot of movement’ (9%)

together accounted for 47% of all near misses. There was a clustering of near misses in the posterior

midline and anterior pelvic sectors with comparatively fewer events seen in the lateral areas (32%,

31% and 20% respectively, p<0.001). Energy sources were associated with 70% identified errors with

ultrasonic scalpel devices used in 46% of all near miss events. Laparoscopic graspers were involved in

23%. Overall, 91% of near misses were executional in nature primarily ‘over action of a step’ (40%),

‘wrong location’ (25%) and ‘wrong object’ (18%).

Reliability

Excellent inter-rater reliability was seen for EAES grade 1 errors with identical grades applied in

92.7% of events (κ=0.86, 95%CI 0.83-0.89, p<0.001). In the 101 events with a discrepancy, 94

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differed by one grade. 2.5% of events were not considered to represent an error by the second

examiner.

Blinded test-retest reliability assessment was performed on the 2D3D trial videos on average 12

months after first assessment (range 9-14). Excellent agreement was observed (κ=0.88, 95%CI 0.85-

0.9, p<0.001) with 89.7% receiving an identical EAES grade. Amongst the differing scores all but

seven were one grade discrepancies (8%). 2% of previous identified events were not considered as

an error upon second assessment.

Clinical validity

Cases containing any major intraoperative event (n=45, 25.7%) contained more errors and near

misses (8 (6-12) vs. 5 (3-7) and 5 (3-7) vs. 3 (2-5) respectively, both p<0.001). 85 (48.6%) patients

developed early morbidity with more near miss errors seen in these cases (4 (3-6) vs. 3 (2-4),

p<0.001). Case near miss numbers were associated with the number of 30-day morbidity events as

well as the associated Clavien-Dindo grade (table 3). Higher number of near miss errors were

observed in patients that underwent unplanned re-operation or developed an anastomotic leak but

this was not statistically significant (n=10, 5 (2-5) vs 3 (3-7), p=0.172 and n=8, 5 (2-5) vs 3 (3-7),

p=0.165 respectively). Near misses were not significantly associated with length of hospital stay

(rs=0.174, p=0.283) or any TME specific histopathological outcomes (table 4).

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Discussion

Despite the wide implementation of safety measures, surgery still contributes to a significant

proportion of in-hospital adverse events (4). Despite reports that technical errors are commonplace

in surgical procedures the intraoperative period receives little scrutiny resulting in under reporting

(5, 8, 14). Following strategies widely employed in high risk industries, we aimed to identify

intraoperative near misses during advanced laparoscopic surgery. We also sought to report the

frequency, nature and clinical impact of apparent near miss events.

In this study evaluating 175 laparoscopic TME operations performed by credentialed surgeons within

two multicentre randomized controlled trials together with matched robust clinical data, errors are

frequently observed and present in the vast majority of procedures. We adopted a validated

structured reporting framework in order to categorize intraoperative events. A broad range of

events were observed with contrasting underlying mechanisms and strikingly, a wide variety in

associated consequences. The majority of operative events were near misses that would typically be

otherwise ignored in routine clinical practice.

Although the absolute differences were small, we observed an association between the number of

apparent near miss events and the development of early patient morbidity as well as the number

and severity of these complications. This suggests these actions are erroneously considered to be

non-consequential and may represent a novel surrogate performance assessment marker. Their

observed frequency would enhance analysis attempts with potential advantages over focussing on

less commonly encountered major events. No utility for TME specific histopathological outcomes

was observed in this study.

Near miss analysis and the methodology used here is expected to be generalisable to other surgical

procedures and specialities. Previous research demonstrated an association between intraoperative

technical performance and clinical outcomes in laparoscopic surgery (11, 32, 33). Bonrath and

colleagues characterised near miss events within 54 bariatric procedures but without clinical

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validation data (14). Our study represents the first investigation reporting clinical implications of

near misses in advanced laparoscopic surgery in addition to describing the underlying mechanism.

In this study, we adhered to a standardised error definition which was confirmed with reliability

assessments. Application of the validated OCHRA methodology successfully identified and

categorized events within the complex intraoperative period. This underpinned the development of

an adverse event severity classification which has been adopted by the EAES (17). The detailed event

information obtained described high risk periods and their underlying error mechanism which could

inform general and surgeon specific strategies for future avoidance.

Excellent test-retest and inter-rater reliability was observed for error detection and categorization

exceeding thresholds typically required for high stake assessment settings. Despite the complexity of

the intraoperative period over 92% of all adverse events were unchanged from the initial

assessment by both the original and external observer. The clinical validity displayed here

strengthens the calls for wider use of case video review as a quality assurance tool (34, 35).

Adoption of our approach mirrors the longstanding approach taken by high risk industries where

near-miss reporting is encouraged and considered important learning opportunities (6, 36).

Outcomes from errors are highly variable meaning repetition risks a worse result (18). This principle

underpins the industrial safety pyramid where the ratio of one major injury for each 29 minor

injuries arising from 300 no injury accidents and 600 unsafe conditions has been repeatedly

reproduced and widely quoted in safety culture (18, 36). Our data also follow this pyramidal

structure although in surgical practice we observed one major consequential error (EAES 3 or 4) for

approximately each 20 near misses (figure 1). This data suggests that operative performance could

arguably be considered as higher risk than any other industry involving interaction between humans

and complex systems. It is of further concern that, unlike industry, presently surgeons and

healthcare systems are not reliably capturing nor learning from these events preventing pre-emptive

interventions (5, 14).

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Although this study represents the largest exploration near misses in laparoscopic surgery and the

first with matched clinical data, a number of limitations are present. All available ALaCaRT videos

were reviewed presenting a theoretical selection bias as there were 192 completed laparoscopic

TME cases in the trial. Video review captures causative actions and has been used to drive quality

improvements but contributory nontechnical and human factors that may impact the procedure are

not captured (37-39). As surgeons were aware of case recordings there is a risk that the Hawthorne

effect altered performance. Although the EAES classification was designed and supported by an

expert working group the acceptability or medicolegal consequences of intraoperative error

reporting require dedicated study (17, 40). Despite the ability to directly observe laparoscopic

surgical performance routine clinical reporting is hampered by the associated time and resource

requirements which primarily limits such reviews to educational and research settings. Post-

operative care was delivered according to local protocols and this variation may have impacted

clinical outcome data. We studied specialist performance and our findings should not be assumed to

apply to the resident level (14). Our findings suggest that near misses should not be accepted nor

ignored when observed by trainers and perfect performance should be the aspiration rather than

absence of major events. It was beyond the ability of both trials to standardise the experience or

role of the assistant surgeon.

Although this project presents a reliable and valid system for reporting operative events including

near misses, cultural changes may be required before wider application. Acknowledgment that

technical errors are common within our procedures and aspiring to move away from blame cultures

towards supportive learning environments aiming to avoid future repetition are laudable goals and

could represent a new route towards transparency and improved surgical safety.

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Conclusion

Intraoperative adverse events can be reliably and objectively captured in advanced laparoscopic

surgery. Near misses are commonplace and correlate with clinical outcomes and should not be

ignored. Near miss analysis may represent a novel surrogate assessment method for intraoperative

technical performance.

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Figure Legends

Figure 1 The industrial and surgical near miss models. The surgical ratio is seen to be unfavourable

when compared with the Heinrich industrial model with one major intraoperative event

encountered for every 19.4 near misses (18, 36).

Table 1 Description and analysis start points for each surgical task. Hierarchical task analysis adapted

from the international laparoscopic TME standardisation consensus (29). Asterix denotes subtask not

captured on video recordings.

Table 2 The European Association of Endoscopic Surgeons intraoperative adverse event classification

with error grade data. A pyramidal distribution is seen with near misses accounting for the majority

of identified events. Major intraoperative events are comparatively infrequent.

Table 3 30 day morbidity data. Near miss data is closely associated with the development of

morbidity including the number and severity of events.

Table 4 Histopathological TME specimen analysis data. Near misses were not seen to be associated

with any TME specific outcome. Missing data not included in the pathology report was excluded.

Supplementary Table 1 Patient and tumour characteristics. Scale variables are reported as mean and

standard deviation.

Supplementary Table 2 OCHRA external error mode data for near miss events. Data is displayed for

each operative task phase.

Supplementary Table 3 Near miss external error mode results broken down by operative task phase.

Supplementary Table 4 Instruments associated with each near miss event

Supplementary Table 5 The pelvic spatial location for all near misses.

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Supplementary Digital Content – Video 1: A near miss error (EAES grade 1). The stapler has been

closed but the colonic rotation is identified and corrected with no consequence to the procedure or

patient.

Supplementary Digital Content - Video 2: The diathermy overshoot incises adjacent peritoneum but

without the need for corrective action (EAES grade 1 – near miss error).

Supplementary Digital Content - Video 3: Whilst preparing the inferior mesenteric artery pedicle for

division the swap dissection triggers bleeding requires correction (EAES grade 2). The application of

the second clip is blind and meets the error definition although there is no adverse consequence

(EAES grade 1 – near miss).

Supplementary Digital Content - Video 4: The surgeon accepts a very limited view whilst applying a

clip to the inferior mesenteric vein. It becomes apparent the clip is in contact with the duodenum

and is removed (EAES grade 2)

Supplementary Digital Content - Video 5: During the anterior TME dissection an inadvertent full

thickness vaginal injury is made (swab visible). A repair is performed with alteration in post-

operative and post-discharge care with impact upon the patient (EAES grade 3).

Supplementary Digital Content - Video 6: During application of the stapler to divide the bowel the

previous staple line is disrupted by the forceful instrument use. The faecal spill resulted in the need

for immediate major corrective action. The patient required unplanned intensive care support and

early re-operation (EAES grade 4).

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