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Dr Mark Luscombe Consultant Anaesthetics/Critical Care Doncaster Royal Infirmary.

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Presentation on theme: "Dr Mark Luscombe Consultant Anaesthetics/Critical Care Doncaster Royal Infirmary."— Presentation transcript:

1 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 = % to %)

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 = % 95% CI = % to % Compared with NZ %

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 (NZ) Weight = 2.52 x Age (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 as the 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= 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: 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 Work Sheffield Children’s Hospital Validation Study Luscombe MD, Owens BD, Burke D. Ages up to 16yrs Sheffield n= Interim Results: Formula Mean Weight Diff 1-10yrs 11-16yrs Mean Weight Diff 11-12yrs Mean Weight Diff (all) 2(age+4)22.45%59.43%51.02%34.14% 3(age) %17.93%12.81%7.45%

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: A M Fredriks, S van Buuren, et al, Arch Dis Child 2000;82:107–112 Jain, A Fighting Obesity, BMJ 2004;328; The advanced life support group, Advanced Paediatric Life Support, Fourth Edition, BMJ Publishing Group 2004 The Dominion Post NZ December 2004 North & South MagazineNZ May 2004 Weight = 3(age) + 7


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