Sitting & Pressure

SITTING & PRESSURE
By Darren Salinger, M.D., OB/GYN
& Melanie Loomos, Inventor

In modern society, sitting takes up an increasing amount of time, both at home and at work. It has been concluded there is a considerable shift to sedentary work in industrialized countries (3).

1881 Analysis of Contact Stresses

The original analysis of contact stresses which lead to pressure-related problems while sitting was published in 1881 by Heinrich Hertz (5).

6 Hours Sitting May Cause Pressure Sore

A healthy individual can develop a pressure sore in six to twelve hours if left undisturbed in the same position (7). A single pressure sore costs more than $8,000 to heal. The yearly costs of treating pressure sores and related problems have been estimated to be almost $1 billion (9).

One study found that 63 percent of patients who sat for an unlimited period of time developed pressure sores whereas only 7 percent of patients developed pressure sores who sat for maximum periods of two hours (1).

Limiting sitting time is only one starting point in preventing pressure sores. Other possibilities include appropriate posture and pressure-reducing seat cushions (1).

In a test of six pressure-relieving devices, the air doughnut was found to be the least effective in reducing inter-surface pressures. None of the devices tested eliminated the inter-surface pressures generated by sitting in one position (7).

To prevent tissue damage, people must be able to shift their weight or be assisted to alternate pressure points (7).

External Pressure = 1/2 Internal Pressure

Externally measured pressure under the butt bones is only one half of the internal pressure. Given the pressures that are prevalent, Staarink (1995) found it amazing that more people do not get pressure ulcers (1).

Risk Factors for Pressure Sores

Studies have implicated factors such as posture and posture changes, impact loading of tissue, elevated temperature and humidity, age, nutritional status, general health, activity level, body stature and shear stress in the development of pressure sores (4).

Shear Force & Pressure Sores

The interest in shear stems from the observation that shear increases the possibility of causing a pressure sore (6). In 1958, it was Reichel who started to focus attention on shear force, which is defined as a force parallel to a surface (2). It is important to reduce shear force as much as possible (6). Avoidance of shear force is as important as avoidance of direct pressure (8).

Snijders (1984) showed that the inclination and the position of a backrest as well as the angle of the seat surface influence the shear force on the seat (3). The proper combination of backrest and seat inclination can reduce shear forces on the seat and on the sitter.

In tests done on healthy young subjects, it was found that when little shear is accepted, a fixed inclination between seat and backrest should be chosen between 90 degrees and 95 degrees (3). When a person is sitting down, the weight of the body is distributed over the supporting surfaces. The distributed shear and pressure result in forces that act on four major body points:
▪ The Feet
▪ The Butt Bones
▪ The Top of the Hip Bones
▪ The Chest

Shear Stresses Reduced – 90N to 5N

In a study measuring shear stresses on wheelchairs, using healthy young subjects, different seat angles were tested. Previous measurements showed that a total shear force on the seat of a foldable wheelchair could become as high as 90N when the seat is horizontal (2). When the seat slant is 8 degrees forward, the shear force becomes smaller than 5N in healthy subjects (2). The assumption is made that if the unfavorable effect of shear stress can be measured in healthy, young subjects, the effect for the hospitalized geriatric and paraplegic population will be even worse (2).

Enveloping Cushion

The enveloping property of a seat cushion is a measure of its tendency to wrap around the object it supports. When the body adopts a sitting posture, the weight of the body is distributed over the supporting surfaces (3). A good enveloping cushion provides a large contact area and a uniform stress distribution (9).

Medium density foam results in the lowest shear stresses and compressive stresses tested. Soft foam results in the next lowest shear and compressive stresses because soft foam tends to “bottom out” and cause pressure from the surface below the foam.

Caution: Temperature Sensitive Foam

Researchers caution against materials in seat surfaces that react to body temperature because there is a risk of rising temperatures and increased humidity which can lead to pressure sores (1), as well as other pressure-related problems.

Researchers conclude that the use of armrests in the case of healthy persons has a very limited pressure-reducing effect but may help stabilize posture.

  1. Applied Nursing Research, Vol. 12, No. 3, August 1999, pp. 136-142, “Sitting Posture and Prevention of Pressure Ulcers,” written by Tom Defloor, MScN, N.N.; and Maria H.F. Grypdonck, Ph.D., RN, Nursing Sciences, University of Gent, Belgium.
  2.  Scandinavian Journal of Rehabilitation Medicine, 29: 131-136, 1997, “Shear Stress Measured on Beds and Wheelchairs,” written by R.H.M. Goossens, Ph.D.; C.J. Snijders, Ph.D., T.G. Holscher, Mac; W. Chr. Heerens, Ph.D.; and A. E. Holman, MSc.
  3.  Journal of Biomechanics, Vol. 28, No. 2, pp. 225-230, 1995, “Design Criteria for the Reduction of Shear Forces in Beds and Seats,” written by R.H.M. Goossens and C.J. Snijders, Erasmus University, Rotterdam, Faculty of Medicine, Department of Biomedical Physics and Technology, The Netherlands.
  4. Journal of Rehabilitation Research and Development, Vol. 29, No. 4, 1992, pp. 21 – 31, Department of Veterans Affairs, “Comparative Effects of Posture on Pressure and Shear at the Body-Seat Interface,” written by Douglas A. Hobson, Ph.D., School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh, P.A. U.S.A.
  5.  Journal of Rehabilitation Research and Development, Vol. 27, No. 2, 1990, pp. 135 – 140, Department of Veterans Affairs, “Reduction of Sitting Pressures with Custom Contoured Cushions,” written by Stephen Sprigle, Ph.D.; Kao-Chi Chung, Ph.D.; Clifford E. Brubaker, Ph.D., University of Virginia, Rehabilitation Engineering Center, U.S.A.
  6.  Journal of Rehabilitation Research and Development, Vol. 27, No. 3, 1990, pp. 239 – 246, Department of Veterans Affairs, “Sitting Forces and Wheelchair Mechanics,” written by Paul Gilsdorf, B.S.; Robert Patterson, Ph.D.; Steven Fisher, M.D.; Nancy Appel, P.T., Department of Physical Medicine and Rehabilitation, University of Minnesota, U.S.A.
  7.  American Journal of Nursing, 1987, “Sitting Easy: How Six Pressure-Relieving Devices Stack up,” written by Robin Charges, RN, M.A., M.S.N.; and Bettie S. Jackson, RN, Ed.D., F.A.A.N., Montefiore Medical Center, N.Y., U.S.A.
  8.  Arch. Phys. Med. Rehabil., Vol. 60, July, 1979, “Shear vs. Pressure as Causative Factors in Skin Blood Flow Occlusion,” written by Leon Bennett, MAE; David Kavner, DEng; Bok K. Lee, M.D.; Frieda A. Trainor, Ph.D., Veterans Administration Prosthetic Center, N.Y., U.S.A.
  9.  J. Biomechanics, Vol. 15, No. 7, 1982, “Model Experiments to Study the Stress Distributions in a Seated Buttock,” Narender P. Reddy, Himanshu Patel, George Van B. Cochran, Biomechanics Research Unit, Helen Hayes Hospital; and John B. Brunski, Center for Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, N.Y., U.S.A.

OSHA Whistleblower Online Complaint Form

Trade Release

Department of Labor, United States of America

U.S. Department of Labor
Occupational Safety and Health Administration
Office of Communications
Washington, D.C.
www.osha.gov

For Immediate Release
July 28, 2017
Contact: Office of Communications
Phone: 202-693-1999

OSHA revises its online whistleblower complaint form

WASHINGTON – The Occupational Safety and Health Administration recently revised its online whistleblower complaint form to help users file a complaint with the appropriate agency. The form provides workers with another option for submitting retaliation complaints to the U.S. Department of Labor’s OSHA.

The updated form guides individuals as they file a complaint through the process, providing essential questions at the beginning so they can better understand and exercise their rights under relevant laws. One significant improvement to the system includes pop-up boxes with information about various agencies for individuals who indicate that they have engaged in protected activity that may be addressed by an agency other than OSHA. The new form is available in English and Spanish.

“Workers who report unsafe conditions and wrongdoing have a range of legal protections from retaliation,” said Deputy Assistant Secretary of Labor for Occupational Safety and Health Loren Sweatt. “The revised online complaint form works to ensure whistleblowers file their complaints with the appropriate federal agency for prompt action.”

In addition to the online form, workers can file complaints by fax, mail, or hand-delivery; contacting the agency at 800-321-6742; or calling an OSHA regional or area office.

OSHA enforces the whistleblower provisions of 22 statutes protecting employees who report violations of various securities laws, trucking, airline, nuclear power, pipeline, environmental, rail, public transportation, workplace safety and health, and consumer protection laws. Detailed information on employee whistleblower rights, including fact sheets, is available online at http://www.whistleblowers.gov/.

Under the Occupational Safety and Health Act of 1970, employers are responsible for providing safe and healthful workplaces for their employees. OSHA’s role is to ensure these conditions for America’s working men and women by setting and enforcing standards, and providing training, education and assistance. For more information, visit www.osha.gov.

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OSHA Electronic Filing By August 1, 2017

Trade Release

Department of Labor, United States of America

U.S. Department of Labor
Occupational Safety and Health Administration
Office of Communications
Washington, D.C.
www.osha.gov
For Immediate Release
July 14, 2017
Contact: Office of Communications
Phone: 202-693-1999

OSHA launches application to electronically submit injury and illness data on August 1

WASHINGTON – The Occupational Safety and Health Administration will launch on Aug. 1, 2017, the Injury Tracking Application (ITA). The Web-based form allows employers to electronically submit required injury and illness data from their completed 2016 OSHA Form 300A. The application will be accessible from the ITA webpage.
Last month, OSHA published a notice of proposed rulemaking to extend the deadline for submitting 2016 Form 300A to Dec. 1, 2017, to allow affected entities sufficient time to familiarize themselves with the electronic reporting system, and to provide the new administration an opportunity to review the new electronic reporting requirements prior to their implementation.
The data submission process involves four steps: (1) Creating an establishment; (2) adding 300A summary data; (3) submitting data to OSHA; and (4) reviewing the confirmation email. The secure website offers three options for data submission. One option will enable users to manually enter data into a web form. Another option will give users the ability to upload a CSV file to process single or multiple establishments at the same time. A third option will allow users of automated recordkeeping systems to transmit data electronically via an application programming interface.
The ITA webpage also includes information on reporting requirements, a list of frequently asked questions and a link to request assistance with completing the form.
Under the Occupational Safety and Health Act of 1970, employers are responsible for providing safe and healthful workplaces for their employees. OSHA’s role is to ensure these conditions for America’s working men and women by setting and enforcing standards, and providing training, education and assistance. For more information, visit www.osha.gov.
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PREVENTION NEEDS RESOURCES

Textbook of Pain, 1998, “Prevention of Disability due to Chronic Musculoskeletal Pain,” written by Steven James Linton:

The above-mentioned chapter in the Textbook of Pain, “examines procedures designed for use in health-care settings to prevent disability due to musculoskeletal pain.”

The following statement is made:

“Because musculoskeletal pain is a major source of suffering, health care, and utilization of compensation, there is a definite need for prevention.  However, prevention is not an easy task because disability is related to a developmental process in which multidimensional factors operate over time to produce significant lifestyle changes.  Research on risk factors indicates that although medical and workplace factors are obvious, psychosocial variables are central to the transition from acute to chronic pain.  The early identification of ‘at-risk’ patients is a key to allocating resources and initiating secondary prevention.”

“Unfortunately, we do not yet understand the exact mechanisms that produce musculoskeletal pain.”

ACUTE PAIN

“Acute pain – Pain which is generally defined as pain up to about three weeks is characterized by temporary decreases in activity, reliance on medication, and help-seeking.  It is accompanied by psychological distress; for example, fear, anxiety and worry, in addition to beliefs that pain is controllable through medical and active coping…The patient may have organic findings as well as muscle spasms.

SUBACUTE PAIN

“Subacute pain – Pain which is considered to be between 3 and 12 weeks.  Patients may exhibit altering patterns of increasing and decreasing activity, and withdraw or become reliant on medication.”

PERSISTENT OR CHRONIC PAIN

“Persistent or chronic pain – Pain which is defined as more than 3 months’ duration, activities may have decreased sharply. . .The pain becomes more constant although patients may experience ‘good’ and ‘bad’ periods.”

RECURRENT MUSCULOSKELETAL PAIN

“Musculoskeletal pain is usually recurrent in nature.  While most episodes of back pain remit rather quickly and most people return to work within 6 weeks, (Reid, et al., 1997), the majority of sufferers will experience several episodes of pain during the course of a year, (Frymoyer, 1992; Nachemson, 1992; VonKorff, 1994; Linton & Hallden, 1997).”

50 % OF ACUTE BACK PAIN SUFFERERS HAVE PAIN 6 – 12 MONTHS LATER

“More than 50 percent of patients with acute back pain will experience another episode within a year (Nachemson, 1992), and prospective studies indicate that almost half will still have significant problems 6 – 12 months later, (Philips & Grant, 1991; VonKorff, 1994; Linton & Hallden, 1997).”

MUSCULOSKELETAL PAIN = LEADING CAUSE OF EARLY PENSIONS

“Firstly, a large number of people suffer from musculoskeletal pain, making it a leading health-care problem even though only a minority develop persistent dysfunction.  Musculoskeletal pain is a leading cause of health-care visits, particularly in primary care,  sick absenteeism, and early pensions, (Frymoyer, 1992; Nachemson, 1992; Skovron, 1992).  However, several studies indicate that over 90 percent of those off work with an acute episode of back pain will return within 3 months, (Waddell, 1996;  Reid, et al., 1997).”

“Secondly, as shown above, musculoskeletal pain is recurrent in nature even though most patients return to work rather quickly after an acute episode.  Although acute sufferers usually feel better and return to work within a few weeks, this does not mean that they have recovered fully or permanently.”

“Thirdly, while up to 85 percent of the population will suffer from musculoskeletal pain, only a small number will account for most of the costs, (Nachemson, 1992; Skovron, 1992; Waddell, 1996).  In general, less than 10 percent of the sufferers may consume up to 75 percent of the resources, (VonKorff, 1994; Reid, et al., 1997).  Thus preventing disability and high-cost cases may result in large economic savings, so that these people constitute a special target for prevention programs.”

MUSCULOSKELETAL PAIN IN SWEDEN & THE NETHERLANDS

“Further, most of the money at this time is spent on compensation, while relatively little is spent on treatment, and almost nothing is invested in prevention.  In Sweden, about 85 percent of the total resources for musculoskeletal pain are spent on compensation as compared to 15 percent for all treatments and drugs, a figure which has remained fairly constant over a 15-year period, (Linton, 1998).”

“Similarly, in The Netherlands, a recent study of all costs due to back pain showed that 93 percent involved compensation and only 7 percent involved treatment, (Van Tulder, et al., 1995).”

PREVENTION NEEDS RESOURCES

“Consequently, until prevention is granted more resources, programs need to be relatively cheap; and this suggests incorporating them into existing practice routines.”

ERGONOMIC RISK FACTORS TO PREVENT

“A host of ergonomic factors, for example, lifting, heavy work, twisting, bending, manual handling, and repetitive work have been found to be associated with musculoskeletal pain, (Pope, et al., 1991; Skovron, 1992).”

“A recent review of some 60 studies revealed a relationship between musculoskeletal pain problems and job demands, control, monotonous work, time pressure, and perceived workload, (Bongers, et al., 1993).”

“If the problem does not remit within 2 – 4 weeks, a formal screening procedure is suggested.”

Ergonomics and Truck Drivers

2) Sangyo Eiseigaku Zasshi, 2000, Jan; 42(1):6-16, written by Koda S, Yasuda N., Sugihara Y., Ohara H., Udo H., Otani T., Hisashige A., Ogawa T., Toyama H., Kochi Medical School, Department of Public Health, Japan:

The above-mentioned study was a questionnaire survey which analyzed work-related health problems among truck drivers.

“134 local truck drivers, 199 long-distance truck drivers, and 71 clerical workers were analyzed. . .The prevalence rates of work factors affecting health problems of truck drivers were significantly higher than those of clerical workers in the items on irregular shift work, working environment, working posture, handling heavy materials, job stress due to overloading and working time, and limited time off.

The prevalence rates for subjective symptoms (ringing in the ears, neck pain, and low back pain) and present illnesses (hypertension, ulcers in the digestive tract, back injuries, whiplash injuries and hemorrhoids) among truck driers were significantly higher than those of clerical workers.”

SAFETY MONTH – Keep Each Other Safe

Let’s help keep each other safe this National Safety Month

U.S. Department of Labor

Occupational Safety and Health Administration

Office of Communications

202-693-1999

Department of Labor, United States of America

Let’s help Keep Each Other Safe this National Safety Month

OSHA joins the National Safety Council and thousands of organizations across the country in recognizing June as National Safety Month. According to NSC, preventable deaths are at an all-time high in America. In fact, more than 130,000 people die needlessly every year – one every four minutes. As part of an effort to emphasize the importance of safety both on and off the job, NSC’s Keep Each Other Safe campaign emphasizes the importance of safety and health at work, on the roads, and in our homes and communities. Visit the National Safety Month website to take the SafeAtWork pledge and access downloadable materials, including a poster, tips sheets, and social media graphics. You can also register for a free webinar taking place on June 22.

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ERGONOMICS

Ergonomics is the science of fitting jobs to people, including anatomy, physiology, and psychology. Ergonomic design is the application of this body of knowledge to the design of the workplace (i.e., work tasks, equipment, environment) for safe and efficient use by workers.
Up to 85 percent of the population will suffer from musculoskeletal pain. When workers sit incorrectly, specifically in a posture that is not ergonomically correct for the individual, they can experience musculoskeletal pain. Because musculoskeletal pain is a major source of suffering, health care, and utilization of compensation, there is a definite need for prevention (2).
A large number of people suffer from musculoskeletal pain, making it a leading health-care problem. . .Musculoskeletal pain is a leading cause of health-care visits, particularly in primary care, sick absenteeism, and early pensions. . .Thus preventing disability and high-cost cases may result in large economic savings (2).
Until prevention is granted more resources, programs need to be relatively cheap; and this suggests incorporating them into existing practice routines (2).
A host of ergonomic factors have been found to be associated with musculoskeletal pain, such as lifting, heavy work, twisting, bending, manual handling, and repetitive work.
Studies have shown that people with herniated inter-vertebral discs often have a history of an activity or occupation involving repetitive forward bending. Forward bending has been clearly recognized as a risk factor for low back pain (3).
The body posture of sedentary workers, especially in offices, and of school children has long been a concern of orthopedists and physiologists. The increasing number of office positions, of seated factory workers, of people sitting in cars and airplanes, even of seated soldiers, has augmented the concern about “unhealthful” sitting postures. Complaints about lower back pains are widespread among people who commonly work in the sitting position (4).
As a result of this very common pain and suffering, the Occupational Safety & Health Administration (OSHA) has created a standard, 29 CFR Part 1910, which was first published on February 8, 2000, to explain the benefits of prevention of musculoskeletal disorders to both employers and employees.
OSHA expects its workable, practical approach to prevent an average of 460,000 injuries annually and to save businesses $9.1 billion annually because of reduced workplace injuries and greater productivity, with a $27,700 savings in direct costs for each musculoskeletal disorder prevented (1).
OSHA estimates that the cost to an employer to implement the new ergonomics approach will be an average of $250 per work station per year, or a total of $4.5 billion to industry per year. This contrasts with business and industry groups that estimate it will cost U.S. businesses between $18 billion and $120 billion per year (1).

OSHA’s suggestions are as follows:

  • There should be management leadership and employee participation in your ergonomics program.
  • Management should identify and assess any hazards.
  • Employees should be trained to identify, prevent and control possible hazards through information and training. Any ergonomics program you set up should also be evaluated for effectiveness.

REFERENCES:

  1. CBA Report, Cincinnati Bar Association, March, 2001: “Is There Light at the End of the Carpal Tunnel?” written by Ann W. DeVoe, Esq.
  2.  Textbook of Pain, 1998, “Prevention of Disability due to Chronic Musculoskeletal Pain,” written by Steven James Litton.
  3.  Spine, Volume 21, Number 1, pp.71-78, 1996, “Analysis of Lumbar Spine and Hip Motion During Forward Bending in Subjects with and Without a History of Low Back Pain,” written by Marcia A. Esola, M.S., P.T.; Philip W. McClure, M.S., P.T.; G. Kelley Fitzgerald, M.S., P.T.; and Sorin Siegler, Ph.D., U.S.A.
  4. Industrial Medicine, Vol. 38, No. 4, April, 1969, Orthopedics, “Ergonomics in the Design of Office Furniture,” written by K. H. Eberhard Kroemer, Dr. Ing.; Joan C. Robinette, Aerospace Medical Research Laboratory, Aerospace Medical Division, Wright-Paterson Air Force Base, Ohio.