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Type and Title of Submission


Title:

Weighing Scales and Stadiometers. The need for accurate instruments in adult nutrition support.

Description:

Category:

Clinical

Does the submission relate to the general implementation of all NICE guidance?

No

Does the submission relate to the implementation of a specific piece of NICE guidance?

Yes

Full title of NICE guidance:

CG32 - Nutrition Support in Adults

Category(s) that most closely reflects the nature of the submission:

Implementation policy
Audit tool
Screening adults for malnutrition

Is the submission industry-sponsored in any way?

Yes
This work has been accepted by a BAPEN (British Association of Parenteral & Enteral Nutrition) committee on shared learning for uploading onto the BAPEN website.


Description of submission


Aim

To improve the accuracy of identifying malnourished patients by improving the accuracy and reproducibility of weighing scales and stadiometers on adult wards in Southampton General Hospital.

Objectives

To examine: 1. The availability, accuracy and reproducibility of weighing scales and stadiometers and the extent to which weighing scales conform to the UK Weighing Federation recommendations (accurate to within 0.2kg). 2. The effect of inaccurate instruments on nutritional screening. 3. To improve and streamline the process of purchasing appropriate weighing scales and stadiometers.

Context

Two previous audits (May 2002 and May 2004) showed that variation exists between weighing scales used within Southampton University Hospitals NHS Trust. On investigation there was no streamlined process of ordering and purchasing appropriate scales (that met UK Weighing Federation Guidelines) within the hospital. The accuracy of stadiometers was assessed using two stainless steel rods: 6 foot and 4 foot, certified by Trading Standards County Council - linked to the National Weight and Standards Laboratory. A standard reference weight of 60.8kg was obtained from the local Equipment Laboratory to test the accuracy of weighing scales. Duplicate measurements were made on the instruments using the above reference standards. Weighing scales were zeroed before measurements were taken. The audit was undertaken in September 2006 and involved co-operation between Hospital Wards, Supplies Department and the Equipment/Maintenance Library. Duplicate measurements were made on the instruments using the above reference standards. A key initiative of the 'Nutrition Support in Adults' NICE Guidelines is the screening for malnutrition in patients on admission to hospital and ongoing weekly re-screening during admission. This allows early identification of patients who maybe at risk of malnutrition so interventions can be put in place to combat further malnourishment and/or improve nutritional status. Part of the screening process should assess a patients weight and height to work out body mass index (BMI) and percentage unintentional weight loss. The correct identification of malnourished patients depends on the accuracy and reliability (reproducibility) of weighing scales and stadiometers.

Methods

1. All in-patient adults wards (n=47) had access to weighing scales. 2. Only 27 wards had stadiometers. 3. Of 113 weighing scales (standing, sitting and hoist) 85 were electronic and 28 were manual. 4. Fourteen of these scales were broken and unusable. 5. The precision (reproducibility) of scales was very good. 6. Manual scales deviated from the standard by -6.3kg to +2.3kg. Electronic scales from -0.5kg to +0.7kg. 7. For a height of 1.70m this translates to a measurement error on BMI ranging from -2.2 to +0.9kg/m2 for manual scales, and from -0.17 to +0.24/m2 for electronic scales. 8. Sixty eight percent of manual scales were in error by more than 0.2kg compared to 11% of the electronic scales. 9. With the exception of one stadiometer which underestimated reference length by 2.78cm, the remaining stadiometers (n=27) provided measurements that deviated from the reference 6 foot rod by -0.38cm to +0.72cm and from the 4 foot rod by -0.22cm to +0.58cm. 10. For a weight of 60.8kg and a height of 1.83m this translates to an error on BMI ranging from +0.57kg/m2 to -0.14kg/m2 respectively (from +0.08 to -0.14kg/m2 when the stadiometer which underestimated reference length by 2.78cm was excluded).

Results and evaluation

Actions taken: 1. Fourteen manual scales (three of which were bathroom scales) were disposed of. Accurate scales were evenly distributed around wards. 2. The stadiometer that read incorrectly by 2.78cm was removed. 3. In partnership with the Equipment Library a procedure is now in place to ensure that appropriate clinical scales and stadiometers are purchased, maintained and distributed to wards. 4. A plan to continue to re-audit was established to ensure sustained use of accurate and reliable instruments. Impact: This audit has: 1. Improved the accuracy of nutritional screening. 2. Multidisciplinary impact, affecting all types of wards, which may share equipment, and the types of patients, including those transferring from one ward to another. 3. Relevance to the use of weight and height for other purposes, such as assessment of drug dosage (e.g. for chemotherapy) and fluid balance (daily changes). 4. This work has been accepted by a BAPEN committee on shared learning and uploaded onto the BAPEN website.

Key learning points

1. Scales change location within hospital when wards borrow scales or when their own are broken/being repaired. When wards move they may or may not take their own scales. Scales need to be clearly marked with which ward or clinical area they belong too. 2. Wards that have a majority of older patients find they do not require/use stand on scales as a large number of their patients have poor mobility. Only sit on and hoist scales were routinely used on such wards. 3. Electronic scale 'chargers/leads' are often broken by people wheeling the scales off while they are still plugged into the wall socket. A clear sign on the scales to remind people to unplug first is helpful. 4. Standing scales are easier to clean than sitting scales so are useful on some wards to use with patients in side rooms who are isolated due to infection. 5. Once scales are deemed 'out of order' or unrepairable they are to be replaced by class 3 or above. The UK Weighing Federation Regulations states that from 1 January 2003, scales with CE approval 3 or better are to be used in hospital for the 'weighing of patients for the purposes of monitoring, diagnosis and medical treatment'. 6. Liaise with Equipment Stores/Supplies and provide explicit information to wards on the most appropriate clinical scales and stadiometers to order and the ordering process. Ensure your Equipment Store has a record of all scales being used and that these scales are calibrated at least annually. 7. Equipment stores/supplies should always have a stock of appropriate chargers to replace broken chargers and/or a process for wards to order new/extra chargers

View the supporting material

Contact Details

Name:William Stanley
Job Title:Dietitian
Organisation:Southampton University Hospitals NHS Trust
Address:Nutrition and Dietetics Department, Level D, Mailpoint 32, Tremona Road, Southampton general Hospita
Town:Southampton
County:Hampshire
Postcode:SO16 6YD
Phone:02380796072
Email:william.stanley@suht.swest.nhs.uk
Fax:02380798665

 

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Copyright 2014 National Institute for Health and Care Excellence. All rights reserved.