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Minimally Invasive Therapy. 2011;20:267–275
ORIGINAL ARTICLE
Indicating shortcomings in surgical lighting systems
ARJAN J. KNULST
1,*
, RIK MOOIJWEER
1
, FRANK W. JANSEN
1,2
,
LAURENTS P.S. STASSEN
1,3,4
, JENNY DANKELMAN
1
1
Delft University of Technology, Faculty of Mechanical, Maritime and Materials Engineering, Dept. of BioMechanical
Engineering, Delft, The Netherlands,
2
Leiden University Medical Center, Dept. of Gynecology, Leiden, The Netherlands,
3
Reinier de Graaf Hospital, Department of Surgery, Delft, The Netherlands, and
4
Maastricht University Medical Center,
Dept. of Surgery, Maastricht, The Netherlands
Abstract
Ergonomic problems of surgical lighting systems have been indicated by surgeons; however, the underlying causes are not
clear. The aim of this study is to assess the problems in detail. Luminaire use during 46 hours of surgery was observed and
quantified. Furthermore, a questionnaire on perceived illumination of and usability problems with surgical luminaires was
issued among OR-staff in 13 hospitals. The results showed that every 7.5 minutes a luminaire action (LA) takes place, intended
to reposition the luminaire. Of these LAs, 74% were performed by surgeons and residents. For 64% of these LAs the surgical
tasks of the OR-staff were interrupted. The amount of LAs to obtain a well-lit wound, the illumination level, shadows, and the
illumination of deep wounds were most frequently indicated lighting aspects needing improvement. Different kinematic
aspects of the pendant system of the lights that influence usability were also mentioned: High forces for repositioning, ease of
focusing and aiming, ease of moving, collisions of the luminaire, entangling of pendant arms, and maneuverability. Based on
these results conclusions regarding the improvement of surgical lighting systems are formulated. Focus for improvements
should be on minimizing the need for repositioning the luminaire, and on minimizing the effort for repositioning.
Key words: Ergonomics, equipment, operating room technology, surgical lighting, usability
Introduction
For many years, illumination of wounds during sur-
gery has been done by surgical luminaires. Such a
surgical lighting system (SLS) basically consists of a
large, heavy luminaire suspended from the wall or
ceiling by a two-arm pendant system. The luminaire
has been designed such that high-intensity light is
supplied to the wound while minimizing shadows of
heads and hands of the surgical team. The pendant
system has been designed to allow great flexibility
in positioning of the luminaire and to stabilize the
position of the luminaire in a certain position.
Although the fundamental design of the SLS has
not been changed for years, surgeons still complain
about their SLSs. Ergonomic shortcomings of several
aspects in operating rooms, including surgical lighting
have been indicated by different authors (1–8).
A German and an Australian study both have indi-
cated a need for ergonomic improvements of the
lighting system (7,8). Complaints varied from collid-
ing pendant arms to lights banging against heads and
from insufficient illumination to one-handed adjust-
ments of the lights being impossible. The underlying
causes of these problems and how often and in what
situations these problems occur have not been stud-
ied. For improvement of SLSs, more detailed infor-
mation on shortcomings and problems of SLSs is
needed.
The aim of this study was to assess the shortcom-
ings of SLSs in more detail and to indicate areas of
interest for improvements in the design of SLSs.
An observational study in the operating room (OR)
during various types of surgery was used to detect and
Correspondence: A. Knulst, Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft Universityof
Technology, Mekelweg 2, 2628 CD Delft, The Netherlands. Fax: +31-152784717. E-mail: a.j.knulst@tudelft.nl
ISSN 1364-5706 print/ISSN 1365-2931 online Ó2011 Informa Healthcare
DOI: 10.3109/13645706.2010.534169
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quantify problems of perioperative luminaire usage.
An online questionnaire was used to extend the
observed findings by the user experience of both
surgeons and assistants to different SLSs and to
different Dutch hospitals. The outcome of the study
pinpoints areas of interest for improving SLSs.
Material and methods
Observational study
The study was carried out in the Reinier de Graaf
Hospital in Delft, a large non-university teach-
ing hospital. Observations were done in two ORs
having the same SLS consisting of a large main
luminaire (Berchtold Chromophare C950, Berchtold,
Charleston, SC, USA) and a small auxiliary luminaire
(Berchtold Chromophare D530 plus). Both lumi-
naires have an adjustable focus and illumination level,
and six degrees of freedom (three translations of the
luminaire, two rotations of the luminaire and one
rotation of the complete SLS around its central ceiling
mount).
In the study the use of the OR luminaires during
46 hours of surgery (14 procedures) was observed.
The surgical procedures were selected with the
surgeons for both their routine nature and likeliness
for luminaire actions (LAs). Some procedures
included multiple wound locations at different
locations of the body, some had large wound areas
and others had narrow and deep wounds. The
selected procedures were: Six gastrointestinal, two
vascular, three breast, and two thyroid gland surgical
procedures.
During the surgery all SLS-related actions of any
OR staff were recorded, initially only on a predefined
fill-out spreadsheet, and during the last ten proce-
dures also by a video camera. The video camera
captured only the SLS and OR staff interacting
with the SLS, the patient remained out of the cam-
era’s sight. OR staff was asked to explain the reason
for the LA, but only if the clinical situation allowed
this communication with the observer.
Afterwards, the video recordings were analyzed
manually and the results were added to the spread-
sheet. The complete spreadsheet listed:
.The function of the luminaire operator (LO)
performing the LA: Surgeon, resident, assisting
nurse, or circulating nurse;
.whether the LO was actually performing surgical
tasks at the moment of LA;
.the type of the LA: Translating or rotating the
luminaire, adapting the illumination level, or
adapting the focus of the light;
.the duration of the LA, defined from the
moment that the operator starts looking for
the luminaire to begin interaction until the LO
ends his interaction by continuing his original
task;
.whether relocations of the luminaire did take
place along the shortest route in 3D space;
.whether the relocation was one- or two-handed;
.the phase of surgery - four phases were
determined:
(1) initializing - the team is ready to start, but
no incision is made yet
(2) surgery:
(a) opening - from first incision to the place-
ment of retractors
(b) surgical tasks - from placement of
retractors until removal of the retractors
(c) closing - from removal of the retractors
until the last stitch
(3) finalizing - the wound is closed, but still
some actions to the patient are being
performed;
.any additional comments on the LA.
Questionnaire
To extend our findings from the observational study
to other hospitals an online questionnaire was formu-
lated. Thirteen hospitals were included, both univer-
sity and non-university teaching hospitals. Each
questionnaire was tailored to the SLSs installed in
those hospitals. The questionnaires were distributed
in each hospital among surgeons, residents, and OR
nurses by surgeons that supported the study.
The questionnaire consisted of two parts:
.A series of questions to profile the participants,
and to let them indicate procedures where light-
ing is perceived as cumbersome;
.items in which the participants had to indicate
their most used SLS from a listing of pictures
and whether or not different aspects for lighting
and usability of this SLS had to be improved.
The results of the questionnaire were exported to
MS Excel for analysis.
Results
Observational study
During the observed 46 hours of surgery, a total of
364 LAs were noticed, resulting in an average of one
268 A.J. Knulst et al.
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LA every 7.5 minutes. All those LAs were identified as
repositioning actions of the luminaire. The light
beam’s focus or the illumination levels were never
adapted during the observation period. The dominant
reason (97%) for the LAs was a change of the
surgeon’s area of interest where optimal vision was
needed.
Figure 1 shows which OR staff member performed
the LAs during surgery as percentage of the total
number of LAs. The surgeons performed 45% of
all observed LAs, and in 97% of those LAs they
interrupted their surgical tasks to do the LA. Resi-
dents took 25% of the LAs, during which they inter-
rupted their surgical tasks in 73% of the cases.
Assisting nurses took 22% of the LAs (0% interrupt-
ing surgical tasks) and circulating nurses took 7% of
the LAs (0% interrupting surgical tasks). In total, in
64% of all LAs surgical tasks were interrupted for
repositioning the light.
Figure 2 displays in what phases of surgery the LAs
occurred. Most LAs (67%) took place during
phase 2b, where actual surgery in the wound was
being performed. During the opening and closing
of the wound 30% of the LAs were done, mainly
because the knife or the needle driver were followed
with the light pattern when progressing along the line
of incision.
The LAs that were recorded on video (249 LAs)
could be more extensively analyzed afterwards.
Figure 3 shows a histogram of the duration of the
LAs, stacked by surgical phase. Most LAs (78%) took
less than eight seconds to complete the action. The
remaining 22% LAs took longer to complete because
of complications during the LA.
The median LA durations - overall and per phase of
surgery - are given in Figure 4. The outliers indicate
the most problematic adaptations of the SLS. Clearly,
most complications occurred during surgery phases
2a–2c, where they have the highest impact on distrac-
tion of the surgical team.
Figure 5 depicts the observed complications:
.Mechanicalproblems (24 events):These problems
included high forces, requiring two-handed adap-
tations; locking of the pendant system, in which
moving it by operating the sterile handle is
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
Circulating
nurse
Functions within the OR team
LA(f)/∑LA(f) [%]
LA
LA performing ST
LA devided over OR staff function, N = 364
Surgeon Resident Assisting nurse
Figure 1. Luminaire actions (LA) performed by OR-staff members. In many LA the staff member was simultaneously performing surgical
tasks (ST) that were interrupted for the LA.
Shortcomings in surgical lighting systems 269
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completely impossible, in some cases the circulat-
ing nurse had to help with the repositioning.
.Collisions of the luminaire against any object
(17 events): When moving the luminaire around,
it bumps into other lights, against heads of OR-
staff, against its own ceiling mount, and against
IV-poles.
.Out of reach: Surgeon had to stand up (four
events) because the lights were hard to reach or
control from a sitting posture.
If such complications occurred, they caused the
median duration of the LAs to double, as is shown
in Figure 6.
Figure 7 shows whether the LA was a purely trans-
lational movement of the luminaire, or a purely rota-
tional movement, or a combination of these. Almost
30% were pure rotations of the luminaire, consisting
of slight adjustments of the location of the light
pattern on the wound. Most LAs (66%) were combi-
nations of translations and rotations, either because of
larger changes of the light pattern location, or because
of change of the angle of the light beam.
The video analysis showed that in 56% of all LAs
the luminaire was not repositioned from any point A
to B along the shortest possible path, but along an
alternative trajectory. LAs where the shortest path was
followed took about 66% the median duration of a
non-shortest path LA (4.5 vs. 6.8 s).
Questionnaire
Part 1. The questionnaire was completed by 98 OR
staff members from 12 hospitals, of whom 43 (43%)
were surgeons, 16 (16%) were residents, and
40 (40%) were OR nurses. Most participants were
female (57%) and 43% were male. Of the surgeons,
51% were general surgeons, 16% vascular surgeons,
and the remaining 33% were either orthopedic,
trauma, thoracic, or gynecological surgeons. Most
participants (91%) were working in ORs equipped
with two luminaires, and two groups of each 4% were
working with one or three luminaires. Many of the
surgeons (88%) indicated that they experienced prob-
lematic lighting during surgery. The top four exam-
ples of procedures that have problematic lighting that
were mentioned are: Transthoracic surgery (23%),
(deep) pelvic surgery (21%), rectal surgery (15%),
and deep abdominal surgery (15%). In general, the
problematic types of surgery seem to have a deep
wound with a narrow entrance to the cavity.
Part 2. Figure 8 shows where OR staff saw needs for
improvement on nine light-related aspects of SLSs.
The results for each aspect of lighting are split for
suggestions of surgeons, residents, and OR-nurses.
The most frequently indicated areas of attention
for improvements –and thus the most perceived
problems- were: The illumination of deep wounds,
the frequency of repositioning the light to keep proper
illumination, reduction of shadows, and the illumi-
nation level of the light beam.
Figure 9 displays where OR staff indicated room for
improvement on eight usability-related aspects of
SLSs. The results for each aspect of usability were
subdivided in suggestions of surgeons, residents, and
OR-nurses. Compared to Figure 8, the general need
for improvements on usability seems to be higher than
LA per procedure phase, N = 364
0%
10%
20%
30%
40%
50%
60%
70%
2.b
Operation
3. Finalizing
Phases during surgery
LA per phase (%)
1. Initializing 2a. Opening 2c. Closing
Figure 2. Luminaire actions (LA) performed in different phases of the surgical procedure.
270 A.J. Knulst et al.
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LA durations per phase, N = 249
0
5
10
15
20
25
30
35
40
1. Initializing,
N = 10
2a. Opening,
N = 40
2b. Surgical
tasks, N = 152
2c. Closing,
N = 47
Overall,
N = 249
Phases during surgery
LA duration [s]
Figure 4. Boxplot displaying luminaire action (LA) durations during surgery, analyzed for the complete dataset (Overall) and per phase of
surgery (phase 1 to 2c).
Luminaire action durations, from video, N = 249
0
10
20
30
40
50
60
37135
Duration [s]
# of LAs per LA duration
1. initializing
2a. Opening
2b. Surgical tasks
2c. Closing
7 9 11 13 15 17 19 21 23 25 27 29 31 33 35
Figure 3. Stacked histogram in which the duration of every single luminaire action (LA) that was recorded on video is distributed over one-
second intervals.
Shortcomings in surgical lighting systems 271
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for lighting. Moreover, the indicated aspects for
improvement were not limited to a few items, but
covered almost all questioned aspects. These results
confirm the observed problems in the OR.
Discussion
This study shows that the need for repositioning
the luminaire during surgery is high, and that
repositioning is cumbersome. The focus of improving
surgical lighting systems should be on minimizing
the need for repositioning the luminaire, and on
minimizing the forces required for such actions.
The aim of this study was to assess shortcomings of
surgical lighting systems (SLSs) and indicate areas of
interest for design improvements of SLSs, by observ-
ing SLS usage during 46 hours of surgery and by a
questionnaire filled out by 98 OR-staff members.
It was shown that luminaire actions (LAs) occur
Number of different complications, during 249
recorded LAs
0
5
10
15
20
25
30
Out of reach
Complication
Count
Mechanical
problems
Collisions
Figure 5. Different types of complications in luminaire use that were observed during performing luminaire actions.
LA durations per phase, N = 249
0
5
10
15
20
25
30
35
40
Complication during LA, N = 38
Phases during surgery
LA duration [s]
No complication during LA, N = 211
Figure 6. The effect of complications (Figure 5) during LA on LA duration.
272 A.J. Knulst et al.
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frequently, every 7.5 minutes. Furthermore, it was
shown that those LAs were dominantly done by the
surgeon, interrupting the surgical tasks. The reason
for these LAs was to re-establish good lighting at
changing working areas within wounds, especially
in large wounds, in small deep wounds, and in cases
of multiple wounds. Different mechanical shortcom-
ings of the SLSs caused more than one fifth of the LAs
to be cumbersome to perform and to take more time
to complete. High operating forces and immobility of
Needs for lighting improvements
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Small pattern
size
Large pattern
size
Frequency of
repositioning
Illumination
level
Heat under
luminaire
Heat above
luminaire
Aspects of lighting
Relative response
No
Unknown
Yes
Shadows Deep wounds Reflections
Figure 8. Responses of surgeons (N= 43), residents (N= 16), and OR-nurses (N= 39) on the question whether improvement was needed for
nine different aspects of lighting.
Different adjustment types, from video, N = 249
0%
10%
20%
30%
40%
50%
60%
70%
Only translation
Type of adjustments
Percentage LA types of total LAs
Translation & rotation Only rotation
Figure 7. An overview of the different types of luminaire positioning actions.
Shortcomings in surgical lighting systems 273
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the luminaire in certain positions seemed to cause
most of the LA problems, together with the expected
risk of collision. These observations were also per-
ceived as problematic by OR staff, as shown by the
questionnaire.
The validity of our observational findings was
extended by using a questionnaire in different uni-
versity and non-university teaching hospitals to check
the observed problems of SLSs. The numbers of
hospitals, staff members and different surgical disci-
plines that were included in this questionnaire were
limited. Due to this limitation some problems that are
specific for certain surgical disciplines might be over-
looked. However, the general problems with SLS
use –such as lighting deep wounds, shadows, and
mechanical issues - are likely to be valid in any surgery
as the basic task and setup of the SLS is identical,
although the frequency of problem occurrence might
be different because of differences in the surgical
situation.
Most LAs were performed by surgeons and resi-
dents, while they were performing surgical tasks. This
is logical, as only they can judge when lighting is
insufficiently directed or what improvement in illu-
mination can be expected when the luminaire is
repositioned. Therefore, it is wise that they are in
command of the lighting system. However, it is unde-
sirable that their attention is drawn away from surgery
frequently, for an unnecessarily long period of time
or too intensively. Especially in crucial situations
inadequate lighting or a cumbersome repositioning
process to obtain a well-lit situation was reported to
create potential hazards (8).
A sound surgical lighting solution will provide
always good illumination at a wide range of locations
simultaneously, thus minimizing the need for and
effect of luminaire repositioning. As small-entrance
deep wounds were reported to be difficult to illumi-
nate, the development of tailored lighting solutions
might be advisable for these cases. Surgical headlights
might improve lighting in these cases, but they have
drawbacks in terms of comfort, mobility, and user-
friendliness. In such way, the need for frequent
luminaire repositioning will be reduced. A further
experimental study with wound models –especially
the hard-to-illuminate wounds –and different
illumination concepts, including the use of surgical
headlights, will give better insights into this matter.
Meanwhile, when the need for luminaire reposition-
ing arises, the surgeon should be able to perform this
task with minimal effort and by paying minimal atten-
tion to this secondary task. An important issue is the
high forces that are required to reposition the lumi-
naire, and that are to be exerted in -ergonomically- a
challenging posture: Above the head. These forces
seem to vary with the position of the luminaire relative
to its ceiling mount. Close to this ceiling mount the
required operating forces will increase enormously,
and even cause an immovable luminaire, presumably
because of a severe reduction of the moment arm whilst
friction moments in the pendant system still need to be
overcome. Also the large number of repositioning
via non-shortest paths can be explained by the large
forces in some areas of the workspace. A model is
currently being developed to estimate the contribution
of different mechanical parameters to the required
Needs for usability improvements
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Surgeons
Residents
Nurses
Ease of
focussing
Force for
moving
Shortest path
Aspects of usability
Relative response
No
Unknown
Yes
Ease of
aiming
Ease of
moving
Collisions Entangling Maneuvrability
Figure 9. Responses of surgeons (N= 43), residents (N= 16), and OR-nurses (N= 39) on the question if improvement was needed for
8 different aspects of usability.
274 A.J. Knulst et al.
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operating force in different luminaire positions.
With the help of such a model an improved low-
operating force pendant system can be developed.
Attention should also be paid to the risk of colli-
sions and entanglement of the luminaire or pendant
with heads, other luminaires, or pendant arms. Espe-
cially in ORs with many pendant arms for various
pieces of equipment these collisions and entangle-
ments are problematic. Solving this problem is not
straightforward. A lighting system without pendants
would tackle this aspect, but would induce reduced
mobility and flexibility of the system, causing many
situations hard to illuminate. A robotic, intelligent
pendant system, on the other hand, could avoid
collisions when repositioning the luminaire; however,
this increases complexity and costs. Further analysis
on collision prevention is required.
Conclusion
In conclusion, this study pinpointed illumination and
usability shortcomings of present surgical lighting
systems. The quintessence of improving surgical
luminaires is minimizing the need for repositioning
the luminaire by the surgical team and minimizing the
forces required for these actions. In that way, sur-
geons will be able to concentrate on their main task,
and perform surgery in a well-illuminated wound and
by a user-friendly lighting system.
Acknowledgments
This research is supported by the Dutch Technology
Foundation STW, applied science division of NWO
and the Technology Program of the Ministry of Eco-
nomic Affairs.
Declaration of interest: The authors report no
conflicts of interest. The authors alone are responsible
for the content and writing of the paper.
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