Pediatric Obesity: Patient Safety Issues

1. Pediatric Obesity: Patient Safety Issues Thomas Inge, MD, PhD Associate Professor Pediatrics and Surgery Cincinnati Children’s Hospital Medical Center

2. Objectives At the conclusion of this educational activity, participants should be able to: • Appreciate the challenges of safely caring for extremely obese pediatric patients in the hospital environment • Describe screening procedures to assess surgical risk for severely obese children • Develop a rational approach to medication dosing in obese patients • List specific interventions that can be implemented when caring for obese patients and strategies to provide coordinated, optimal care for this population

3. Body Mass Index • Body Mass Index (BMI): • A measure of weight in relation to height; specifically weight in kilograms divided by the square of height in meters • BMI for age used in children who have not attained final adult stature • Overweight: BMI > 25 kg/m2; • BMI for age >85th percentile • Obese: BMI > 30 kg/m2 • BMI for age >95th percentile • Morbidly obese: BMI > 40 kg/m2 • ? BMI for age >99th percentile

4. Challenges for Pediatric Healthcare Teams • More children with obesity-related comorbidities • More children on “adult” medications • More frequent hospital encounters for heavier patients?

5. Challenges in Caring for Obese Pediatric Patients • Physiologic • Transportation • Physical exam • Diagnostic imaging • Nursing care • Airway management • Venous access • Medication dosing

6. Physiologic Challenges • Increased prevalence potentially occult abnormalities • Metabolic (IR, IGT, DMT2) • Cardiovascular (HTN, atherosclerotic changes, LVH) • Pulmonary (OSAS, asthma, ↓chest compliance, ↓FRC) • Steatohepatitis, fibrosis • Total extracellular volume ↑ in obesity resulting in… • ↑ resting cardiac output → ↑ O2 consumption and ↑ CO2 production • Blood volume decreased in severe obesity (50cc/kg) • Gastric emptying may be decreased • Fat mass is a sponge for lipophilic drugs/agents • Volume of distribution

7. Pharmacology • How does one appropriately dose medications in the obese patient? What is known about pharmacokinetics in obese patients?

8. Medication Dosing Issues • GI absorption not altered by obesity • Marked alteration in pharmacokinetics: altered volume of distribution and renal clearance • Volume of distribution in obesity correlated with drug lipophilicity—drugs with higher affinity for adipose have a larger volume of distribution • Markedly increased: benzodiazepines, thiopentone, phenytoin, verapamil and lidocaine. • Modest increases: methylxanthines, aminoglycosides, vancomycin, ibuprofen, prednisolone and heparin. • Unchanged: digoxin, cimetidine and procainamide

9. Dosing Issues (con’t.) • Protein binding of drugs bound to albumin is not dramatically changed in obesity. • Oxidative drug biotransformation minimally changed in obesity • Drug conjugation uniformly increases as a function of bodyweight in obesity • Drug acetylation may be unchanged in obesity, with only procainamide evaluated at this time. • Renal clearance of drugs is little changed for some drugs evaluated (digoxin, cimetidine, lidocaine, verapamil), and increased for others (aminoglycosides, unmetabolised procainamide).

10. Inhalational Agent Solubilities

11. Medication Dosing Issues • When dosing guidelines not provided, base loading doses on drug’s hydrophilic or lipophilic properties, and ideal body weight (IBW) or total body weight (TBW) • Hydrophilic, normal Vd: • Dosing Weight = IBW + 0.3(TBW-IBW) • Lipophilic, high Vd: use TBW • Maintenance dose should be based on IBW if metabolic clearance is not known Navarro, Bone Marrow Transplant 2003 Brunette DD. Am J Emerg Med. 2004;22:40-7.

12. Transportation Challenges • Need to recruit more personnel • Need multiple slide boards or “hovermat” • Requires use of specially designed soft stretchers, operating room tables, hospital beds • May exceed weight limits of physical plant: • Must provide heavy-duty commodes, exam tables, OR tables, stretchers, hospital beds, mechanical lifts, and wider furniture and wheel chairs

13. Hovermat

16. Physical Exam Challenges • Pannus and increased thickness of subcutaneous fat interferes with auscultation, palpation, and inspection • Positioning the patient is difficult due to decreased mobility • Blood pressure readings may be inaccurate when wrong size cuff used • Pain threshold in obese patients may be higher, further diminishing accuracy of exam

17. Imaging Challenges • Standard radiographs—often cannot fit entire field of image into single film • CT and MRI hindered by weight and circumference restrictions of typically 300-350 lbs • Ultrasound imaging technically difficult Source: Varon J, Marik P. Crit Care Clin. 2001;17:187-200; Boulanger BR, et al. J Trauma.1988;45:52-56; Melanson SW, Heller M. Emerg Med Clin North Am. 1998;16:165-89; McKenney KL. Radiologic Clin North Am. 1999;37:879-93.

19. Imaging quality

20. Know your limits! Inge et.al. J.Ped.Surg. 2004

21. Nursing Care Challenges • Cardiac and pulse oximetry less reliable • Wound care technically difficult • Blood draws and IV access hard to establish • Skin care and pressure sore prevention challenging due to need to move patient often Source: Hahler B. Medsurg Nurs. 2002;11:85-90; Davidson JE, et al. Crit Care Nurs Q. 2003;26:105-18.

22. Airway Management Issues • Bag-valve mask ventilation more difficult • reduced pulmonary compliance • increased chest wall resistance • increased airway resistance • abnormal diaphragmatic positioning • Increased aspiration risk • Larger volume of gastric fluid • Increased intra-abdominal pressure • Higher incidence of GERD in the obese patient

23. Airway Management Issues • Obesity limits physicians view of laryngeal structures during intubation • Australian study of 85 difficult intubations: obesity, limited neck mobility, or mouth opening accounted for two thirds • Interventions to consider in morbidly obese • Intubate in the semierect position • Use the Intubating Laryngeal Mask Airway or Combitube Williamson JA, et al. Anaesth Intensive Care. 1993;21:602-7; Rocke DA, et al. Anesthesiology. 1992;77:67-73.

24. Intubation Laryngeal Mask Airway

25. CHILDHOOD BODY MASS INDEX AND PERI-OPERATIVE COMPLICATIONSNafiu et.al.University of Michigan Medical SchoolAnn Arbor, Michigan • Prevalence of overweight and obesity in children undergoing surgery • Does an association exists between high BMI and the risk of tracked peri-operative complications in a pediatric population?

26. CHILDHOOD BODY MASS INDEX AND PERI-OPERATIVE COMPLICATIONS

27. Frequency of comorbidities between normal weight, overweight and obese children Nafiu NAASO Poster, 2006

28. Obese patients were more frequently ASA class III and IV than overweight or normal weight children, p = 0.0006

29. Frequency of QA events in children

31. Frequency of perioperative QA events by weight status in children

32. Venous Access Challenges • Greater number of skin punctures during catheter placement • Delayed catheter changes with increased infection and thrombosis • Additional personnel needed for positioning and pannus retraction Boulanger BR, et al. Crit Care Clin. 1994;10:613-95.

33. Quality of Care for Obese Patients • Documented delays in medical care • Less likely to receive preventative care • Negative physician attitudes and discrimination • Reported feeling mistreated and misunderstood by medical personnel • Surgeons possibly more reluctant to operate Source: Schwilk B. Anasthesiol Intensivmed Norfallmed Schmerzther. 1995;30:99-107; Heinzelmann M. Am J Surg. 2002;183:179-90.

34. Obesity and Perioperative Mortality • Longer operative times • Increased surgical wound infection rate • Higher risk of sepsis Cruse PJ, Foord R. Surg Clin North Am. 1980;60:27-40

35. Postoperative Complication Rates by Weight Schwilk B. Anasthesiol Intensivmed Norfallmed Schmerzther. 1995;30:99-107

36. What can we do?

37. Treatment Obstacles • Facility Assessment – what is really needed? • Diagnostic equipment limitations • Smart devices for venous access • Transfer assist devices • Staff training (including sensitivity) • New employee orientation (diversity training module?) • Medical/nursing/allied health student curricula • Medication dosing guidelines (EBM)

38. Obesity and Medical Education • Rotations on bariatric surgery service have improved student’s knowledge base • Interventions in medical school using video audio and written components have lead to improved attitudes towards obese patients Source: Nanasiak M, Murr MM. Obes Surg. 2001;11:677-9;Wiese HJ, et al. Int J Obes Relat Metab Disord. 1992;16:859-68.

39. Pre-op Screening • Anesthesia / Cardiology Consults • Likely comorbidities ruled out or controlled • Diabetes • Asthma • Obstructive Sleep Apnea • Cardiomyopathy (ECHO, EKG) • DVT prophylaxis • Consider issues around drug dosing (over/under) • Postoperative care needs discussed

40. Take-Home Points • Pediatric obesity is an epidemic in the US and an increasing percentage of patients will be classified as obese • Providing excellent care to this population is challenging and requires special attention and often the use of customized equipment • Airway management is particularly risky and care givers should be prepared to use rescue techniques

41. Take-Home Points • Medication dosing must often be customized to this population • Care givers must be mindful of potential biases that can influence interactions with patients and affect the quality of care • Efforts should be made to increase curriculum at the medical school level focusing on the care of the obese patient • Efforts should be made to develop evidence based care pathways for obese patients