Weighing Mechanisms

TO DIAGNOSE LOW BIRTH WEIGHT NEONATES

Prevention/Diagnostic
Diagnostic/Prevention
  • PREVENTION
  • DIAGNOSTIC
  • TREATMENT
  • OVERVIEW
  • TECHNOLOGY Characteristics
  • Weighing Mechanisms
    Representative Product

    Condition
    Globally, approximately one in six neonates is born at a low birth weight (<2500 grams). This is an important predictor of neonatal morbidity and mortality whether the neonate is premature or small due to intrauterine growth restriction. Weighing allows extra attention to help diagnose pathologies which are much more prevalent in low birth weight infants. For instance, infant respiratory distress syndrome is much more common among infants of very low birth weight. Knowing the birth weight is low allows careful checks to see if the neonate has respiratory distress syndrome which will be diagnosed clinically.

    Mechanism of Action
    Electronic and spring scales are the most common tools for determining birth weight. Electronic scales require a power source and typically use a strain gauge whose resistance varies with very small, elastic deformation under load. Spring scales are typically simpler, less expensive, and do not require power. However, these devices' analog display and requirement for calibration make them less advantageous where high accurracy is valuable.

     

    In community health settings, the caregiver places the baby in a sling of known weight and hangs the sling from a calibrated scale. The spring elastically deforms under the load, giving a readout. In clinical settings, accurate knowledge of an infant's weight can be used to track hydration, nutrition, and waste evacuation.

     

    Current use in High-resource settings
    Electronic scales with resolution of 2g are common in high-resource settings. For infants in intensive care, the electronic scale may be integrated into the incubator so that the patient need not be moved to be weighed. Nearly all babies are weighed at birth and periodically for check ups. Sick and premature newborns are typically measured multiple times per day.

    Application in Low-resource settings
    Traditional Birth Attendants (TBAs) may approximate weight by feel, but rarely carry weight measurement devices. Skilled birth attendants are more likely to carry spring scales to deliveries, or use them in clinics. Hospitals frequently have analog or digital tabletop scales to weigh neonates.

     

    Related technologies in development

    Birthweigh III

    REPRESENTATIVE DEVICES

    MAKE
    MODEL
    PRICE
    TECH
    STATUS
    NOTES

    Seca

    727 Pediatric Scale
    $1,625
    Electronic
    Marketed
    2g precision, serial output, gold standard

    Bebesounds

    Digital Baby Scale
    $40
    Electronic
    Marketed
    Primarily a consumer product

    Unicef

    BebeWey
    $5.24
    Spring
    Marketed
    Binary classification >/<2500g

    PATH

    BirthWeight III
    $5.00
    Spring
    Tested
    Color coded, tactile classification in 3 tiers

    Generic

    Spring Scale
    $2.86
    Spring
    Marketed
    Analog numerical output, general purpose

  • CHARACTERISTICS OF REPRESENTATIVE PRODUCT

    TECHNOLOGY CHARACTERISTICS (Birthweigh III by PATH)

    Operational Parameters

    POTENTIAL OPPORTUNITIES FOR IMPROVEMENT

    SKILLS

    REQUIRED

    Intended end user
    Training required
    Time required per use
    Traditional or skilled attendant
    Minutes
    Minutes

    Visual and tactile coding make this device a compelling solution classification in the <2kg, 2-2.5kg, and >2.5kg bands even in the absence of literacy or vision.

    ENVIRONMENT/ INFRASTRUCTURE

    Power required
    Waste collection
    Complementary technologies required
    Temperature and storage
    Maintenance
    None
    None
    None
    None
    Negligible

    The coil spring has been tested >10,000 cycles to within 100g for each of the three weight bands, minimizing the need for periodic calibration.

    COST

    Device Cost (Approx)
    Cost/course (Approx)
    $5
    n/a

    Product is not commercially available. PATH open to commercialization.

    OTHER

    Portability
    Regulatory
    Efficacy
    <200g
    Sensitivity of 87.8%, specificity of 99.6% when identifying neonates <2000g

    Transport to an appropriate setting of care; intensive care depending on indication(s)

Sources: Deorari, Ashok and Vinod Paul. Neonatal Equipment: Everything that you would like to know. 3rd Ed 2006. Sagar. Printers & Publishers. New Delhi. BirthWeigh III. Technology Solutions for Global Health. PATH January 2008. L Mullany et al. A low cost, colour coded, hand held spring scale accurately categorises birth weight in low resource settings, Arch Dis Child 2006;91:410–413