1 / 33

Paediatric Weight Estimation: Small change – Big Difference?

Paediatric Weight Estimation: Small change – Big Difference?. Dr Mark Luscombe Consultant Anaesthetics/Critical Care Doncaster Royal Infirmary. Today’s Talk. Aim to look at two questions: Does the current APLS weight estimation formula remain valid? Is there a better alternative?.

mendel
Download Presentation

Paediatric Weight Estimation: Small change – Big Difference?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Paediatric Weight Estimation: Small change – Big Difference? Dr Mark Luscombe Consultant Anaesthetics/Critical Care Doncaster Royal Infirmary

  2. Today’s Talk • Aim to look at two questions: • Does the current APLS weight estimation formula remain valid? • Is there a better alternative?

  3. Increasing Weight • Concern over obesity in children • Is it just extremes or are children in general heavier? • Is there a real weight change or just a perceived change?

  4. North & South Magazine

  5. Medical Literature

  6. Population Characteristics

  7. Pilot Studies • First Study in Whangarei Hospital NZ (n=103) • Predicted weight is = 2(Age+4) • Children aged between 1 and 10 yo • Acute or day-case surgery in a 3 month period • Compared recorded weights with predicted weight

  8. Results • 90% children greater than estimated weights • NZ mean weight difference = 24.75% (95% CI = +19.25% to +30.25%)

  9. Pilot Studies • Second Study in Doncaster Royal Infirmary UK (n=134) • Method and Inclusion criteria as previous study

  10. Results • 86%(UK) children greater than estimated weights • UK mean Weight Difference = +18.46% • 95% CI = +14.87% to +22.05% • Compared with NZ +24.75%

  11. Problems & Solutions • Current estimation formula significantly underestimates weight • More accurate formula required •  Use Data to derive new formula

  12. Importance of Weight Estimation • Often needed for critically ill • Relied upon for: • Drug Dosages • Fluid Bolus (& Maintenance) • DC Shock settings • Ventilator settings • Urine output • Decision to ventilate based upon fluid given

  13. New Formula • Include 2 Standard deviations • Draw straight line of best fit • Result is: • Weight = 2.37 x Age + 9.63 (NZ) Weight = 2.52 x Age + 7.56 (UK)

  14. New Formula - Criteria • 1) Simple to use • 2) More accurate than previous • 3) In general should avoid over-estimation of weight • Two Options considered • Weight = 2 x (Age + 5) and • Weight = 2.5x (Age + 4)

  15. Early Conclusions • Children are heavier than predicted by current formula • The current formula is a poor estimate of the modern child’s weight. • Both new formulae tried were more accurate

  16. Pilot studies recommendation - Which New Formula? • Weight = 2x(age+5) • Whilst not as accurate on average asthe other formula tried, it is: • 1) More accurate than Weight = 2x(age+4) • 2) Likely to avoid drug over-dosage • 3) Simple to calculate

  17. Publication • Luscombe M D, “Kids aren’t like what they used to be”: a study of paediatric patient’s weights and their relationship to current weight estimation formulae. British Journal of Anaesthesia 2005; 95(4): 578

  18. Next Step • Larger scale study – need minimum n=400 • Checklist • Proposal • Protocol • Co-researchers • Ethical Approval • Finance Form • Research and development approval at research centre • Collect data and analyse • Statistician • Write it! • Publish

  19. Next Step • Luscombe MD & Owens BD • Data from Queens Medical centre, Nottingham UK, ED database • 6 months data n= 17244 test sets of data. • Age/Weight/Ethnicity/A&E Category

  20. Differences from pilot studies • Many more formulae tested • Check made on weights by A&E category. • Individual ages considered • Graphical representation • Ethnicity considered • Formulae tried : Weight = • 2age+9 • 2age+11 • 2(age+5) • 2(age+6) • 2.5(age+3) • 2.5(age+4) • 3(age+2) • 3(age+3) • 3age+7 • 3age+8

  21. Necessary? • Weights of Category 1 patients (Acute-Life Threatening) recorded = 41.5% • Weights of Category 5 patients (Minor injury to Emergency Nurse Practitioner) = 94.1% • Overall weight recording = 81.7%

  22. Necessary? • Weight estimate is still needed • Previous reasons for accurate weight assessment remain valid i.e. • Drug Dosages • Fluid Bolus (& Maintenance) • DC Shock settings • Ventilator settings • Urine output • Decision to ventilate based upon fluid given • Weight estimate may persist into ICU stay

  23. Additional Information • No evidence base for Weight=2(age+4) found • Fanconi, Wallgren & Collis “Textbook of Paediatrics” 1952 – Weights listed for age groups • Small “audit” type projects had also found more accurate formulae.

  24. Results • All formulae tried were more accurate overall • 3 formulae matching criteria • Weight = 3(age)+7 • Weight = 2.5(age+3) • Weight = 2(age+5) • Weight = 2(age+4) remains poor estimate

  25. Graphical Representation

  26. Which Formula? • Weight = 3(age) + 7 • Mean Weight Difference = 2.48% (95%CI = 2.17% to 2.79%) • Same at age 1 then more accurate at all other ages than current formula. • It is more accurate than all the other formulae from age 6 and older. • Mean weight difference 2(age+4)= 18.8% • (95% CI = 18.42% to 19.18%).

  27. Dissemination • Luscombe MD & Owens BD. Weight estimation in resuscitation: is the current formula still valid? Archives of Disease in Childhood 2007;92:412-415 • Numerous presentations

  28. Any problems? • Formula is an estimate • Overestimate in 4-5-6yrs old group • Only from 1 – 10yrs old • Ethnicity not recorded • Data from one area and in the UK only

  29. Further WorkSheffield Children’s Hospital Validation StudyLuscombe MD, Owens BD, Burke D.Ages up to 16yrsSheffield n= 41792Interim Results:

  30. Further work

  31. Interim Conclusions • Results validate previous study in new population • Weight = 3(age)+7 more accurate 1-10yrs • Weight = 3(age)+7 more accurate 1-16yrs • “Acceptable” accuracy 1-12yrs • Puberty • Males approx 11.5yrs • Females approx 10.5yrs • Formula works from 1 yrs to puberty

  32. Thank you • To ALSG for inviting me. • For your interest. • To Ben Owens and the many who have helped.

  33. Any Questions? • References • Fanconi G, Wallgren A, Collis WRF. Textbook of Paediatrics. William Heinemann Medical Books Ltd, London 1952 • Luscombe M D, “Kids aren’t like what they used to be”: a study of paediatric patient’s weights and their relationship to current weight estimation formulae. British Journal of Anaesthesia 2005; 95(4): 578 • Luscombe MD & Owens BD. Weight estimation in resuscitation: is the current formula still valid? Archives of Disease in Childhood 2007;92:412-415 • A M Fredriks, S van Buuren, et al, Arch Dis Child 2000;82:107–112 • Jain, A Fighting Obesity, BMJ 2004;328;1327-1328 • The advanced life support group, Advanced Paediatric Life Support, Fourth Edition, BMJ Publishing Group 2004 • The Dominion Post NZ December 2004 • North & South Magazine NZ May 2004 Weight = 3(age) + 7

More Related