Suitability Study On Weightless Suspension In Operating Rooms

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SUITABILITY STUDY ON WEIGHTLESS SUSPENSION IN OPERATING

ROOMS: A FINAL REPORT

Prepared for: Steve McMillan, Head of Medical Equipment and SuppliesStryker®

Prepared by: Clarissa Queja, Kinesiology & Health StudentAnnika Richard, Pre-Medical Student

December 9, 2004



College Park, MD 20742

www.umd.edu

Memo

Date: December 9, 2004

To: Steve McMillan, Head of Medical Equipment and Supplies, Stryker®

From: Clarissa Queja, Kinesiology & Health Student, University of MarylandAnnika Richard, Pre-Medical Student, University of Maryland

Subject: Final Report for the Proposal for Weightless Suspension for Operating Room

Personnel

Attached is a final report on our proposal about improving surgical equipment design foroperating room staff. We completed the tasks outlined in our proposal dated October 11, 2004:researching current surgical apparatuses and testing various options to alleviate surgeons’ lowerback pain and to increase the productivity of operating room staff.

First, we performed research on low-back pain caused by surgeons’ static posture during

procedures. Then, along with SSI Robotics®, we designed and tested several models of weightless suspension apparatuses based on standards determined from our research.

Based on the information we gathered, we recommend that the chest support-based model is thebest design for the Voyager Lift™ because it performed the best in our testing. We therefore

propose that the Voyager Lift™ with the chest support feature be incorporated into the i-Suite™ operating room design.

Thank you for the opportunity to research options for enhancing Stryker’s i-Suite™ operatingroom design, as well as helping with surgeons’ problems with low-back pain and injury. We

look forward to the possibility of working on trial installations of the Voyager Lift™ inWashington, DC area hospitals. Please contact Clarissa Queja at (301) 324-1851 or AnnikaRichard at (301) 216-0338 if you have any questions or comments.

Table of Contents

http://www.umd.edu/

http://www.umd.edu/



List of Illustrations …………………………………………………………………..…. iii

Abstract …………………………………………………………………………… ……. iv

Executive Summary ……………………………………………………………… ……. 1

Introduction ………………………………………………………………………. ……. 2

Methods …………………………………………………………………………… ……. 4

1. Performing Research ………………………………………………………. ……. 4

2. Approving Model Designs ……………………………………………………….. 6

3. Testing Models ……………………………………………………………..……. 7

4. Proposing a Final Design ………………………………………………….. ……. 10

Results …………………………………………………………………………….. ……. 11

1. Research Findings …………………………………………………………. ……. 11

2. Model Designs ……………………………………………………………………. 16

3. Model Testing Results ……………………………………………………………. 18

4. Final Design Proposal ……………………………………………………………. 19

Conclusions ……………………………………………………………………….. ……. 20

Recommendations ………………………………………………………………………. 21

Glossary …………………………………………………………………………………. 22

Appendix: Numerical Score Criteria for Testing Models ……………………………. 23

References ………………………………………………………………………….……. 24

List of Illustrations



Figures

Figure 2.1 Model A……………………………………………………………………. 17

Figure 2.2 Model B……………………………………………………………………. 17

Figure 2.3 Model C……………………………………………………………………. 18

Tables

Table 3.1 Model Testing Scores……………………………………………………… 18

Table 3.2 Individual Criteria Scores for Comfort and Ease of Movement and UseMeasurements……………………………………………………………….19

Abstract



“Suitability Study on Weightless Suspension in Operating Rooms: A Final Report”

Prepared by: Clarissa Queja, Kinesiology Student, University of MarylandAnnika Richard, Pre-Medical Student, University of Maryland

Lower back pain and injury are common among surgeons and their assistants because they mustfrequently sit or stand in non-neutral positions for long periods of time. There is a growingconcern over the short-term and long-term effects of surgeons’ poor posture while operating.This report describes a project to design a weightless suspension apparatus in the operating roomto alleviate back pain and to increase the productivity of the surgeons’ and their staff. Weresearched topics such as back pain and injury, ergonomics, weightlessness, and suspensiondevices in order to establish fundamental model-selection criteria. The models produced werethen evaluated according to the six standards. The chest support-based model (B) described inthis report was chosen as the best option to enhance hospital operating rooms. This modelallows the most movement and accuracy, is not too large to install in average size operating

rooms, and is simple to use. Based on the information we gathered and reviewed, werecommend installing the chest support-based Voyager Lift™ apparatus in the i-Suite™operating room design on a trial basis.

Keywords: weightlessness, suspension, operating room, back pain, ergonomics

Executive Summary



Minimally invasive surgery has become increasingly well-known in the last ten years. The

advantages for patients are well-recognized; however, surgeons must cope with disadvantages

caused by an unergonomic working environment. On October 1, 2004, we received approval to

research and test alternative surgical equipment designed to improve operating rooms’

ergonomic designs and alleviate surgeons’ back pain. In our study, we addressed these problems

experienced by many operating room personnel:

• They have dealt with low-back pain and/or injury due to prolonged improper posture

during surgeries.

• They have experienced muscle cramps and fatigue during procedures caused by

unergonomic equipment in the operating room.

This report describes a project to design a weightless suspension apparatus in the operating room

to alleviate back pain as well as increase the productivity of the surgeons and their staff.

The Voyager Lift™, a chest support-based model, described in this report best meets all our

technical and cost criteria. It is feasible because it allows the most movement and accuracy out

of the three models tested, it is not too large to install in average size operating rooms, and it is

simple to use. We recommend installing the apparatus in the i-Suite™ operating room design on

a trial basis. If the trial program proves successful, we further recommend suspension devices,

such as the Voyager Lift™, be installed in more operating rooms in the area. The Voyager Lift™

design provide the best solution to the current problems of surgeons’ low-back pain and injury,

as well as unergonomic workplaces.



Introduction

On October 1, 2004, we received approval for funding for the production of surgical equipment

designed for weightless suspension of operating room personnel. We also received approval to

research and test alternative surgical equipment designed to improve operating rooms’

ergonomic designs and alleviate surgeons’ back pain. This proposal was based on growing

concerns over the short-term and long-term effects of surgeons’ poor posture in operating rooms.

Low-back pain is common among surgeons and their assistants because of poor ergonomic

designs in operating rooms. When a surgeon remains motionless in an overstretched or

physiologically unsuitable position for extended periods of time during a procedure,

musculoskeletal problems may occur. Prolonged sitting or standing, particularly in forward or

slouched positions, can cause muscle fatigue, which can lead to back problems. Creating new

surgical equipment, as this report recommends, would help alleviate surgeons’ back pain as well

as increase the productivity of the operating room staff.

This report presents the findings of our research and testing. We researched back pain and injury

experienced by surgeons, ergonomics in the hospital, and similar weightless suspension devices

currently being used. We designed several models of weightless suspension apparatuses and

established model-selection criteria. In conducting our research, we relied on the expertise of

several individuals knowledgeable about surgical equipment and its importance in operations.

For example, Dr. Daniel Stevenson, a general surgeon at the Anne Arundel Medical Center,

helped us understand the seriousness of prolonged improper posture while in surgical

procedures. We consulted the engineering firm, SSI Robotics®, to build and test different

models based on the results of our research. Finally, this report details our research and



recommends one of the models to be added to the Stryker® i-Suite™ operating room design. We

also recommend that the final model, called the Voyager Lift™, be used in other hospitals and

operating rooms.

We have focused our research on designing surgical equipment solely for weightless suspension

and use in operating rooms in hospitals. The Voyager Lift is intended for the suspension of

surgeons and other operating room personnel to alleviate back pain.

Our most significant findings are as follows:

• The terrible back pains and injuries that surgeons experience daily are caused by strain on

the lower back muscles and prolonged forward, bent motions or positions.

• A suspension device using cables or wires will allow surgeons to maintain a neutral spine

position while allowing them to perform their jobs.

• Model B exhibiting the chest support design received the best score from our model-

selection criteria.

We therefore recommend that the chest support-based model (B) is the best option to enhance

hospital operating rooms. This model allows the most movement and accuracy, is not too large

to install in average size operating rooms, and is simple to use. Based on the information we

gathered and reviewed, we further recommend installing the chest support-based Voyager Lift™

apparatus in the i-Suite™ operating room design on a trial basis. The i-Suite™ model has the

potential of being largely enhanced with the addition of the Voyager Lift™.



The following sections provide additional details about the methods used in our research, the

results we obtained, the conclusions we made from those results, and our recommendations

based on those conclusions.

Methods



We performed several tasks in order to test and chose a final design for the Voyager Lift™. We

first spent some time performing research on similar lifts and machines as well as on the problem

of back pain for surgeons. Using this research, we asked SSI Robotics®

to design several models

for our suspension device. We approved or rejected each design and then chose three (3) to build

as actual models to test. Upon completion of the tests, we analyzed the data and chose the final

model for the Voyager Lift™

. A detailed description of each completed task is outlined below:

1. Performing Research

We completed research in the following areas:

1.1. Past studies on back pain and injury

The National Institute of Neurological Disorders and Stroke, working in association with

the National Institute of Health, has performed several studies on back pain and has

created a comprehensive fact sheet detailing the condition and its causes.

Further studies on lower back injury have been performed by the Statistical Analysis,

Accident Causation and Policy Monitoring Division of Great Britain’s Department of

Transport. The Workplace Safety & Insurance Board has also published data on the

causes and possible prevention of back pain and injury. Together, these reports give a

clear overview of the back problems associated with inappropriate posture.

1.2. Back pain experienced by surgeons

We interviewed several Surgeons and Occupational Therapists in order to get a first-hand

account of the problem of back injury associated with the Medical Surgery profession.

Interviews were performed with Daniel Stevenson, M.D. of Anne Arundel Medical

Center in Annapolis, Maryland, Marie Sharpe and Dr. Joshua Giovanni, M.D. of Thomas



1.5. Similar suspension devises and their mechanisms

Hospitals already have certain suspension devices for their patients, and we compared

and contrasted these different machines to determine their mechanisms. We also

researched what types of equipment different companies and agencies, such as NASA,

are using to suspend people. This information gave us good insight and ideas for the

types of designs to create for our model.

1.6. Feasibility of use in an operating room

The most important aspect of our design is its use in the operating room. We explored

the feasibility of using such a device by looking at similar machinery already used in

hospitals and their operating rooms, estimating the costs and benefits to hospitals, and

predicting the likelihood of the lift being used on a regular basis. We also considered

how the lift would improve the i-Suite™design. By carefully studying and measuring

the model, we determined how our lift would fit in with the machinery already in place

for the i-Suite™

. We also used this information to determine a size range for the

Voyager Lift™ to be incorporated into the design.

2. Approving Model Designs

Engineers at SSI Robotics®

designed several models of weightlessness suspension devices

using the structural and mechanical findings we provided from our research. We considered

each design and approved or rejected it based on standards determined from the research on

similar suspension devices. We chose three (3) final designs, which SSI Robotics®

then built

for us to test.



3. Testing Models

Each one of the three (3) models was tested for several factors according to numerical criteria

scales. The scores for all factors were added up in the end to determine the best model

design. Each factor and the corresponding scale used are described below. A summary chart

of the numerical score criteria is shown in appendix A.

3.1. Size

The three (3) models were already chosen based on the previously determined size limits

so that the final design can be incorporated into the i-Suite™operating room.

However, each model is nevertheless different in size, and a scale was determined to

compare the different dimensions of each. We measured the length, width and height of

each device and assigned a number from 0 to 3 to each dimension.

For length and width, a zero (0) was assigned to any measurement of less than 1.0

meters (m) and more than 3.5 meters (m). A one (1) was assigned to any measurement

in the range of 1.0 m to 1.5 m or 3.0 m to 3.5 m. A two (2) was given to a measurement

in the range of 1.5 m to 2.0 m or 2.5 m to 3.0 m. A three (3) was assigned to any length

in the 2.0 m to 2.5 m range.

For height, we not only obtained a measurement, but also tested whether or not it could

be adjusted. All measurements were taken from the top, where the device would be

attached to the ceiling, down to the end of the fully extended devise. A model received a

score of zero (0) if it was not adjustable and less than 1.0 m or more than 3.0 m high, and

a one (1) if is was not adjustable but within the range of 1.0 m to 3.0 m. This range of

1.0 m to 3.0 m is most appropriate for operating room heights. A model received a

higher score of a two (2) or three (3) if it was adjustable. A two (2) was give for a short



range (less than 2.0 m) adjustment capability, and a three (3) for a wide range (more than

2.0 m) adjustment capability.

3.2. Weight limits

Each one of the models has a certain weight limit, indicating how heavy of a person it

can structurally and mechanically support. Because a larger weight limit allows for a

wider range of use, the scores for this category were given based on increasing values

for weight limit.

A zero (0) corresponds to a limit of less than 100 kg, a one (1) to a limit of less than 150

kg, and a two (2) to a limit of less than 200 kg. The best score of a three (3) was given

to a device with a weight support of more than 200 kg.

3.3. Comfort for surgical personnel

Comfort is a very difficult factor to test because it can be interpreted differently by

different people. We therefore asked a group of ten people to try out each devise and

rate their level of comfort based on the following scale:

(0) = Not comfortable, Hard Material, Awkward positioning

(1) = Somewhat comfortable, Semi-soft material, OK positioning

(2) = Comfortable, Soft material, Good positioning

(3) = Very Comfortable, Very soft material, Excellent positioning

The average score was then taken for each model and considered in the final score

calculation.

3.4. Type of Control for Height and Rotation Adjustment

We measured the way in which the lift can be adjusted in height (up and down motion)

and rotation (left to right motion). Models that can not be adjusted at all received a zero



(0). Models that can only be adjusted by manually moving a switch received a one (1),

whereas those that use a remote control received a two (2). The high score of three (3)

was given to models that have a remote control in combination with a sensor control.

The sensor control uses some type of sensory equipment to move to a specific location

on its own without hitting any other objects or people. A specific location can be

entered digitally, and the machine automatically moves into that position.

3.5. Ease of movement and use

This category is based on how smoothly the machine operates and how user-friendly it

is. Because this factor also changes for different individuals, ten people were asked

again to rate each model and give it a score according to the following criteria:

(0) = Difficult to use, Jerky movement

(1) = Fairly easy to use, Slightly jerky movement

(2) = Easy to use, Smooth movement

(3) = Very easy to use, very smooth movement

The average of these scores was taken to be used in the final score calculation.

3.6. Feasibility of use in hospital operating rooms

We measured the feasibility of using the models in operating rooms to determine if the

size, shape, and ease of use were appropriate for operating room staff. Models that were

not feasible to use received a zero (0). Models that were only suitable for very few or

some operating rooms received a one (1) or two (2), respectively, and models suitable

for use in most operating rooms received a (3). These suitability measurements are

based upon the standard sizes of operating rooms throughout the United States, as taken

from the chart of Standard Operating Room Dimensions on the Stryker® website.



3.7. Production and installation cost (estimated per lift)

The final testing criteria involves the estimated cost for production and installation of

each lift design. The actual monetary amounts will of course vary between hospitals and

areas, but the approximate costs could be determined based on estimated material,

production and installation costs. Models that would cost over $ 3000.00 per lift

received a zero (0). Designs costing from $1500.00 to $ 3000.00 received a one (1),

while those costing between $ 500.00 and $ 1500 received a two (2). Models that would

cost less than $ 500.00 received a score of three (3). Lower costs received higher scores

because we want to minimize the cost to the Stryker®

company and to hospitals.

After completing the tests, all of the individual scores for each criteria were added together to

determine the total score for each model design.

4. Proposing a Final Design

Based on the testing results and the highest total score, the final design was chosen. This

model was then further analyzed and the cost predicted more accurately. The model is now

being proposed for approval along with this report.

Results

In this section, we present the results of our research, design approval, model testing and final

design proposal. The types of models tested, their scores from the analyses, and the final model

chosen for the Voyager Lift™

are described below.

2. Research Findings

The research we completed provided us with a lot of essential information for creating and

testing the models for the Voyager Lift™. Our findings are outlined below:

3.8. Past studies on back pain and injury



From studies performed by the National Institute of Neurological Disorders and Stroke

(NINDS), we learned that back pain is very common among the general population, and

most frequent among both men and women between the ages of 35 and 55. This is the

majority of the working population. The NINDS’s fact sheet further reveals that back

pain and injury are most often caused through incorrect posture, such as prolonged

sitting or bending. Surgeons certainly fall into the category of prolonged bending, as

they must constantly lean over their patients to perform surgeries. Injuries, such as

herniated disks, spinal degeneration and lumbar muscle strains, are very common

amongst people that stand in improper and bent positions for extended periods of time.

Similar conclusions were drawn by the Division of Statistical Analysis, Accident

Causation and Policy Monitoring (SAP) of Great Britain’s Department of Transport.

Although this data comes from the Department of Transport and focuses mainly on back

injuries caused through automobile accidents, it does provide good insight into what

causes these injuries. According to the SAP Division, most accident related back

injuries are caused by strain on the lower back muscles and the forward, bent motion of a

passenger in a car crash. The similarly bent positions for surgeons are what cause their

lower back pains and injuries.

The most comprehensive study on occupations that contribute to back pain and damage

was performed by the Workplace Safety & Insurance Board. Medical Surgery is listed

amongst the list, along with similar professions that require frequent bending, such as

dentistry and auto mechanics.

From these results on past studies, it becomes clear that back injury is a common problem

among surgeons, and that this problem needs to be addressed.

3.9. Interviews with surgeons



To support our findings on the back pain experience by surgeons, we interviewed actual

surgeons and discovered that they do, in fact, suffer from frequent back pain as a result

of their profession. Daniel Stevenson, M.D. of Anne Arundel Medical Center said: “I

have been performing surgeries for 7 years...[and] the back pain is excruciating.” Dr.

Joshua Giovanni, M.D. of Jefferson University Hospital also expressed that “if you have

a weak back, you should consider going into a different field [other than surgery] of

medicine”, suggesting that the there is a lot of strain on surgeons’ backs. Both of the

doctors expressed that they have felt back pain for several years and that they frequently

(at least once a day) feel this pain. They believe that the pain is most likely a result of

their profession, which they have been in for seven years in the case of Dr. Stevenson

and nine years in the case of Dr. Giovanni. When we asked the surgeons what they

would think of a device such as the Voyager Lift™

, they both expressed positive attitudes

towards the idea. Dr. Stevenson even said: “I [wish] someone had come up with the idea

of a lift for surgeons sooner.”

We also interviewed Occupational Therapists, who gave us more information on how

back pain is caused and how it can be prevented. Marie Sharpe, of Thomas Jefferson

University Physical and Occupational Therapy, told us from her own experience with

different patients that surgeons are at the highest risk of developing back injuries out of

all medical professions. She also restated the fact that most back injuries are caused by

standing in improper positions, such as bending forward, for long periods of time.

Ashley Henderson, of Greenbelt Physical Therapy, further supported the statements

made by Mrs. Sharpe and said that “backs are nothing to be fooled around with. You

need to keep your spine in a neutral position at all times to prevent back pain and injuries

from happening.”



As a result of all of these interviews, we concluded that back pain and injuries are major

concerns for surgeons. We also concluded that in order to prevent this pain, surgeons

need to maintain a neutral position for their spines.

3.10. Ergonomics in the hospital, particularly the operating rooms

The idea of a neutral spine position relates directly to ergonomics, which focuses on

providing working environments that allow for optimal body posture while performing a

job. Ergonomics in the operating room is a topic that is increasingly being discussed. To

establish model-selection criteria, we researched operating room design factors because

they greatly influence surgeon fatigue and discomfort during procedures. One of the

main and basic ergonomic factors associated with surgery is the surgeon’s non-neutral

posture during procedures, which causes lower back pain. Many factors contribute to the

surgeon’s posture, such as instrument design, a poorly adjusted operating table height,

and the static body position. This information gave us insight into basic design features

of surgical equipment to create for our model.

3.11. Physics of weightlessness and suspension

Any type of mechanism needs to take into consideration the physical aspects of the

device. In physics, weightlessness refers to the notion of something that is apparently

floating without the weight (due to gravity) having an effect on the object or person.

This generally occurs in the case of something falling with the same acceleration as the

object in which it travels. An example would be an astronaut “floating” in a spaceship

orbiting the Earth.

The concept of suspension is more accurate for our purposes. Suspension, in the physics

sense, refers to a device that can exert a net force on a person or object that equals (in



magnitude) the weight of that person or object due to gravity. The Voyager Lift™ would

therefore need to be supported by strong cables or wires, for instance, so that the tension

in these wires could counteract the forces due to gravity and support the weight of the

device and person on it.

Knowing these definitions of weightlessness and suspension, as well as the physics

concepts behind them, greatly assisted us in developing designs for the Voyager Lift™.

3.12. Similar suspension devises and their mechanisms

We further developed design ideas after looking at similar lifts and suspension devices.

NASA, for example, uses suspension equipment as a part of their astronaut training. In

order to simulate the “floating” experienced in outer space, the Special Hoist Supported

Personnel Lifting Devise pulls up people and allows them to hang in mid-air.

Similar to the NASA suspension apparatus, Hollywood has used the famous Mission

Impossible style suspensions to allow actors and stuntmen to hang from ropes and wires.

This type of suspension could certainly be emulated.

Other types of lifts already exist as well. Hospitals throughout the nation are familiar

with the Hoyer™ lift, which is used to hoist up injured, elderly or overweight people

who cannot stand or sit up by themselves. There are many versions to the lift, some of

which are operated by a manual switch and others that are operated electronically.

Because hospital employees are already familiar with such types of lifts, they would

most likely be more accepting of the concept of lifting surgeons during long surgical

procedures.

3.13. Feasibility of use in an operating room



While hospital staff are familiar with lifts and would most likely support the idea behind

the Voyager Lift™, the machine itself must be feasible for use in the operating room.

The Voyager Lift™ should not be too expensive for the hospitals to purchase. Machines

that exceed $3000.00 would be of little benefit for hospitals. However, with the money

the hospitals can save in worker’s compensation for back injuries and the advantage of

happier and more productive employees, hospitals could certainly gain benefits from

purchasing a Voyager Lift™. The benefits will exceed the costs if the lift can be bought

and installed for under $ 3000.00.

Once installed, we believe that the lifts would be used on a regular basis. Our interviews

with the surgeons (see Results Section 1.2) also support this assumption. The lift would

be most beneficial for surgeons during long procedures, such as cardiac and brain

surgeries, which generally last from three to eight hours. The Voyager Lift™ would

therefore be very feasible to use in hospitals specializing in these types of surgeries.

Other operating rooms would be enhanced with the Voyager Lift™, as well. As part of

the i-Suite™design, the lift would greatly enhance the operating room model. The space

above the operating table is approximately 3.5 meters wide by 3.5 meters long. The

Voyager Lift™, with the proper dimensions, could certainly fit into this space. Our lift

design could therefore be easily incorporated into the i-Suite™model.

Using all of these research results, we concluded that we certainly needed to develop a device

that would allow surgeons to maintain a neutral spine position while allowing them to

perform their jobs. We also concluded that we should develop a type of suspension using

cables or wires and that the device should be fairly easy to operate. The cost of production

and installation should also not exceed $ 3000.00 per lift. Furthermore, we concluded that



the Voyager Lift™ could be incorporated into the i-Suite™ model to greatly enhance the

design.

4. Model Designs

All of the information gathered through research (Section 1, above), was submitted to

engineers at SSI Robotics®, who designed several models of suspension devices using the

structural and mechanical criteria we provided for them. They developed 25 designs, out of

which the three (3) best were chosen to be build and tested. The blueprints of these three

models (A, B and C) are shown below.

2.1 Model A:

Model A uses a

mattress-type

of suspension.

A memory

foam patting

allows for

comfort for the

surgeon, and

the remote

controlled

operationallows for

smooth and

easy

movement.

Model 28Z5

Simple Suspension DeviceAdjustable planeFree 180°RotationAdjustable height

Six Supporting CablesCeiling Mounted SupportsMemory Foam MattressRemote Controlled

Model 28Z5

Simple Suspension DeviceAdjustable planeFree 180°RotationAdjustable height

Six Supporting CablesCeiling Mounted SupportsMemory Foam MattressRemote Controlled

2.3 Model B:

Model B uses a

design similarto Model A in



2.3 Model C :

Model 28A6

Suit SuspensionCustom FitHooks Attached to Back of SuitDurable Wire Support360°Rotation

Model 28A6

Suit SuspensionCustom FitHooks Attached to Back of SuitDurable Wire Support360°Rotation

Model C is

most similar toNASA’s

suspension

device and the

Mission

Impossible-

style

suspension. It

consists of

suits that can

be custom fitfor surgeons.

Hooks on the

back and legs

5. Model Testing Results



The three (3) designs shown above were tested according to the criteria shown in Appendix

A and explained in the methods section (methods 3.1 to 3.7). Below is a chart of our results,

with the appropriate scores for each model shown. Model B has the largest total number of

points.

Table 3.1: Model Testing Scores

Criteria Model A Model B Model C

Length2 3 2

Width 2 3 2

Height 3 3 2

Weight Limit 2 3 2

Comfort for Surgeon* 2 1.8 0.5

Type of Control for Adjustment 2 2 1

Ease of Movement and Use* 1.5 1.8 0.9

Feasibility of Use in the OR 3 3 3

Production and Installation Cost

(per lift)

2 2 3

TOTAL 19.5 22.6 16.4

*Two of the criteria—comfort for surgeon and ease of movement and use—are averages

taken from 10 different people’s opinions on how comfortable and easy to use each

model is. The individual scores are as follows:

Table 3.2: Individual Criteria Scores for Comfort and

Ease of Movement and Use Measurements

Comfort for Surgeon 1 2 3 4 5 6 7 8 9 10 avg

Model A 2 2 1 2 2 3 1 2 2 3 2

Model B 3 2 2 1 1 1 2 2 2 2 1.8

Model C 0 0 1 0 1 1 0 2 0 0 0.5

Ease of Movement and Use 1 2 3 4 5 6 7 8 9 10 avg



Model A 2 1 1 0 2 3 1 2 1 2 1.5

Model B 1 2 2 2 1 3 2 1 2 2 1.8

Model C 1 0 1 0 2 1 0 1 1 2 0.9

These averages were used in the calculation of the final score.

As shown in the chart, model B, with a score of 22.6 out of 27 possible, has the highest

total score, followed by model A with 19.5 points, and then model C, with 16.4 points.

4. Final Design Proposal

Based on the testing results shown above in section 3, model B, with the chest support, is the

best design for the Voyager Lift™ because it performed better with the testing than the other

models did. We therefore propose that model B be incorporated into the i-Suite™ operating

room design. The i-Suite™ model has the potential of being largely enhanced with the

addition of the Voyager Lift™

Conclusions

After carefully analyzing the three models of weightless suspension apparatuses and the model-

selection criteria, we have concluded that Model B of the Voyager Lift with the chest support

suspension is the best option to enhance the i-Suite™ operating room design. The standards we

created stipulate that the apparatus have the following qualities:

• ideal dimensions

• comfort for the surgeon

• easy adjustment control unit

• moderate feasibility for use in operating rooms

• cost for production and installation per unit lift not to exceed $3000



This Voyager Lift™ model received excellent ratings from SSI Robotics® engineering experts

and local surgeons for its size and dimensions, weight limit, and feasibility of use in operating

rooms. This model is also a remote controlled apparatus, which is a moderately easy type of

control for adjustment and movement for the operator. Finally, the Voyager Lift™’s production

and installation cost is very reasonable.

The ideas of suspension and ergonomics in operating rooms have been established in current

literature and have been deemed suitable for surgeons and operating rooms. We recommend that

the Voyager Lift be incorporated into the i-Suite™ operating room design. Moreover, the i-

Suite™ operating room has the potential of being largely enhanced with the addition of the

Voyager Lift™.

Recommendations

We recommend that the chest support-based model of the Voyager Lift™ is the best option to

enhance hospital operating rooms and ease surgeons’ lower back pain. Based on the information

we gathered and assessed in this study, we further recommend installing the Voyager Lift™

apparatus with the chest support feature in the i-Suite™ operating room design on a trial basis.

We believe the i-Suite™ design will be largely enhanced with the addition of the Voyager Lift™

apparatus. If the trial installation is successful, we further recommend that hospitals in the

Washington, DC area put in i-Suite™ operating rooms with the Voyager Lift™ included in them.



In addition, the Voyager Lift™ could be slightly altered and used in other professional fields,

such as dentistry or automobile mechanics. The possibilities for the Voyager Lift™ are endless.



Glossary

herniated disks: the protrusion of a degenerated or fragmented intervertebral disk into theintervertebral foramen, compressing the nerve root

lumbar muscle: the muscle of, near, or situated in the part of the back and sides betweenthe lowest ribs and the pelvis

lumbar strain: also known as low back strain, an injury to the large muscles in the lowback

spinal deterioration: known as spondylosis, degeneration of the spinal column, especiallya fusion and immobilization of the vertebral bones

occupational therapist: a person trained in or engaged in the practice of occupational

therapy, the use of productive or creative activity in the treatment or rehabilitation of physically or emotionally disabled people

neutral (spine) position: the position of an individual's spine where every joint is held inan optimal position to allow an equal distribution of force through the entire structure

Weightlessness (Physics): the state or condition of having little or no weight

Suspension (Physics): the act of suspending something (hanging it from above so itmoves freely)

Tension (Physics): the condition of so being stretched; tautness; a force tending to stretchor elongate something

Hoyer lift: Patient lifts that allow an individual do be lifted and transferred with minimaleffort and greater safety. Some of the main reasons for selecting a Hoyer lift include:Patient too heavy to be transferred without assistance of a lifting device; to preventinjury to the caregiver or the patient during transfers; and the ability to lift patientsfrom the floor

Ergonomics: the applied science of equipment design, as for the workplace, intended tomaximize productivity by reducing operator fatigue and discomfort

Special Hoist Supported Personnel Lifting Device: Device specifically designed to liftand lower persons via a hoist. These devices include hoist supported platforms wherepersonnel occupy the platform during movement.



Appendix A

Numerical Score Criteria for Testing Models

Numerical ScoreFactor

(x) 0 1 2 3Length x < 1.0 m

x > 3.5 m1.0 m < x< 1.5 m3.0 m < x< 3.5 m

1.5 m < x< 2.0 m2.5 m < x< 3.0 m

2.0 m < x < 2.5 m

Width x < 1.0 mx > 3.5 m

1.0 m < x< 1.5 m3.0 m < x< 3.5 m

1.5 m < x< 2.0 m2.5 m < x< 3.0 m

2.0 m < x < 2.5 m

Height(fromceiling)

Not Adjustable,x < 1.0 mx > 3.0 m

Not Adjustable,1.0 m < x< 3.0 m

Adjustable,Short range

(within 2.0 m)

Adjustable,Wide range

(more than 2.0 m)

Weight Limit x < 100 kg x < 150 kg x < 200 kg x > 200 kg

Comfort forSurgeon Not comfortable,Hard Material,Awkward

positioning

Somewhatcomfortable, Semi-soft material, OK

positioning

Comfortable, Softmaterial, Goodpositioning

Very Comfortable,Very soft material,Excellent

positioning

Type of Control forAdjustment

Adjustment NotAvailable

Switch Control Remote Control Remote andSensor Control

Ease of Movementand Use

Difficult to use,Jerky movement

Fairly easy to use,Slightly jerky

movement

Easy to use,Smooth movement

Very easy to use,Very smoothmovement

Feasibility of Use in theOR

Not Feasible Feasible in a fewOperating Rooms

Feasible in someOperating Rooms

Feasible in mostOperating Rooms

Production +InstallationCost (per lift)

x > $ 3000 $1500 < x <$ 3000 $500 < x <$ 1500 x < $ 500



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Suitability Study On Weightless Suspension In Operating Rooms

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