CHILDHOOD OBESITY AND ANESTHESIA

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CHILDHOOD OBESITYAND ANESTHESIA

• BY Rahim Ladak
• Wednesday April 18th, 2007

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OBJECTIVES

• Definition and measurement
• Epidemiology
• Diseases related to obesity
• Obesity and adverse health consequences
• Management Key Points
• Obesity and anesthesia

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OBESITY

• Defined as a condition where fat has accumulated
  to such an extent that health is adversely
  affected
• (WHO definition)
• Characterized by an excess of fat tissue relative
  to lean body mass
• The most common nutritional disease in developed
  countries

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DEFINITION

• Operational definition of childhood obesity
• BMI gt90th but lt97th percentile overweight
• BMI gt97th percentile obese

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MEASUREMENT

• The most prevalent anthropometric measure used in
  childhood obesity is the BMI
• In contrast with adult measures, BMI changes with
  age, paralleling increases in height and weight
• BMI does not account for bone density, body
  shape, or racial differences

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International cut offs for BMI

• Cole et al., BMJ 20003201240-7
• Ages 2-18
• Rigorous statistical analysis to relate BMI in
  children with adult cut off points 25 kg/m2
  (overweight) and 30 kg/m2 (obese)
• Obtained by averaging data from Brazil, Great
  Britain, Hong Kong, Netherlands, Singapore, and US

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International cut offs for BMI

• Overweight
• 2 year old male 18.41
• 10 year old male 19.84
• 15 year old male 23.29

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International cut offs for BMI

• Obese
• 2 year old female 19.81
• 10 year old female 24.11
• 15 year old female 29.11

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Epidemiology and Sociology of Childhood Obesity
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• Prevalence of overweight and obesity in a
  provincial population of Canadian preschool
  children
• Patricia M. Canning, Mary L. Courage and Lynn M.
  Frizzell
• (CMAJ (2004) 171(3))
• Calculated BMI using heights and weights measured
  by public health nurses during the province-wide
  Preschool Health Check Program (2000-2003)
  (n4161)
• Overall, 25.6 of the preschool children in the
  cohort were overweight or obese
• a high proportion of children aged 35 years in
  Newfoundland and Labrador are overweight or
  obese. It appears that prevention measures should
  begin before the age of 3 years

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• Secular trends in the body mass index of Canadian
  children
• M S Tremblay and J D Willms
• (CMAJ (2000) 163(11))
• Changes in society have created the opportunity
  for more sedentary behaviour and the consumption
  of food that is high in kilojoules, which may
  lead to a progressive increase in body mass over
  time
• Nationally representative data from the 1981
  Canada Fitness Survey, the 1988 Campbell's Survey
  on the Well-being of Canadians and the 1996
  National Longitudinal Survey of Children and
  Youth were used
• Regression analyses were used to assess
  population changes in BMI from 1981 to 1996 for
  children aged 713 years

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• Secular trends in the body mass index of Canadian
  children
• M S Tremblay and J D Willms
• (CMAJ (2000) 163(11))
• The prevalence of overweight
• among boys increased from 15 in 1981 to 28.8 in
  1996
• among girls from 15 to 23.6
• The prevalence of obesity in children more than
  doubled over that period
• from 5 to 13.5 for boys
• 11.8 for girls

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• Is the Canadian childhood obesity epidemic
  related to physical inactivity?
• M S Tremblay and J D Willms
• (International Journal of Obesity (2003) 27,
  1100-1105)
• Epidemiological study on a nationally
  representative sample of Canadian children aged
  7-11 years (n7216)
• Sport and physical activity are negatively
  associated with being overweight (10-24 reduced
  risk) or obese (23-43 reduced risk)
• TV watching and video game use are risk factors
  for being overweight (17-44 increased risk) or
  obese (10-61 increased risk).
• study provides evidence supporting the link
  between physical inactivity and obesity of
  Canadian children

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Kids and Food

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• National Geographic (August 2004)
• Americans enjoy one of the most luxurious
  lifestyles on Earth Our food is plentiful. Our
  work is automated. Our leisure is effortless.
  And its killing us.

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GENETICS OF OBESITY
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MONOGENIC CAUSES OF OBESITY

• Mendelian Disorders
• Prader-Willi Syndrome (15q SNRPN)
• Albright Hereditary Osteodystrophy (20q GNAS1)
• Bardet-Biedl Syndrome (7 loci)

• Single Gene Disorders
• Leptin and Leptin Receptor (mice ob/ob and
  db/db)
• Pro-opiomel apocortin (POMC)
• Alpha MSH
• ACTH
• Betha endorphin
• Melanocortin-4 Receptor
• Carboxypeptidase E Prohormone convertase 1

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POLYGENIC CAUSES OF OBESITY

• Candidate genes
• animal studies (rodent models)
• biochemical function
• genome-wide linkage scans 70 putative loci
• chromosomes 2p, 3q, 5p, 6p, 7q, 10p, 11q, 17p,
  20q
• tissue-specific gene expression (testing
  potential)

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GENETICS OF OBESITY
Genetic Obesity
Strong Predisposition
BMI
Slight Predisposition
Genetically Resistant
Obesogenic environment
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DDx of Obesity

• Endocrine Disorders
• Cushings Syndrome
• Hypothyroidism
• GH Deficiency
• Hyperinsulinemia
• Albrights Hereditary Dystrophy
• Brain Damage
• Hypothalamic tumor
• Surgery/Trauma

• Genetic Syndromes
• Prader-Willi Syndrome
• Alstrom
• Bardet-Biedl
• Carpenter
• Cohen
• Monogenic Disorders (i.e. leptin deficiency)
• Primary (simple/ exogenous) Obesity
• Multifactorial

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CONSEQUENCES OF OBESITY
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CONSEQUENCES OF OBESITY
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CONSEQUENCES OF OBESITY
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Obese Child
Family Personal Hx PE
Suspect Syndromal Obesity
No
Yes
Suspect Endocrine Disorder
Suspect Genetic Syndrome
Yes
Suspect Cushings, Hypothyroidism GH Deficiency
No
Chromosomal Typing Molecular Biology
Primary Obesity
Endocrine Testing Neuro Imaging Molecular Biology
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New clinical guidelines to obesity

• Important message
• A modest weight loss of 5-10 of body weight is
  beneficial
• Weight maintenance and prevention of weight
  regain should be considered as long-term goals

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Key management recommendations

• Measure BMI and waist circumference (?94 cm euro
  men, ?80 cm euro women, ?85 cm Japanese men, ?90
  cm Japanese women)
• Measure BP, HR, fasting glucose, and lipid
  profile
• Assess and treat comorbidities and health risks
  associated with obesity
• Assess and screen for depression, eating and mood
  disorders
• Assess readiness to change and barriers to weight
  loss

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Key Management Recommendations

• Health team is required
• Dietary support (adult caloric reduction 500
  kcal/d) to achieve 5-10 body weight loss over 6
  months
• Prescribe 30 minutes daily activity of moderate
  intensity
• Consider pharmacotherapy and/or bariatric surgery
• Continue regular reviews and reinforce goals for
  weight loss and maintenance

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More Guidance is Needed

• Smoking
• Pregnancy adverse outcomes such as GDM, PIH,
  C/S, and wound infection
• Maternal obesity and infant macrosomia (each 1 kg
  increase in birth weight translates into a 30
  increase in risk of adolescence obesity
  Pediatrics 2003111e221-6)

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Obesity and Anesthesia
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Pre-op/History

• History and Physical
• ROS
• Airway
• Heart
• Lungs
• Eyes hypoxia and hypercarbia leads to
  angiogenesis
• Previous anesthesia

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Obesity and the Airway

• Obese children can present with difficult airways
• Fleshy cheeks, large tongue, large palatal,
  pharyngeal, and supralaryngeal soft tissue may
  narrow the airway

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Airway

• Mallampati, mouth opening, tongue size,
  thyromental distance, sternomental distance, neck
  circumference
• Predictibility of difficult intubation neither
  obesity or BMI predicted problems with tracheal
  intubation BUT HIGH MALLAMPATI SCORE ? 3 and
  LARGE NECK CIRCUMFERENCE MAY INCREASE THE
  POTENTIAL FOR DIFFICULT LARYNGOSCOPY AND
  INTUBATION
• At 40 cm probability of difficulty 5 and at 60
  cm probability of difficulty is 35
• Anesthesia and Analgesia, Mar 2002. 732-736

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Obesity and the Respiratory System

• Sleep Apnea
• Asthma
• Decreased FRC, ERV, VC, and IC
• Atelectasis causing V/Q mismatch
• Increased risk of aspiration from GERD
• Difficult airways (ventilate and intubate)

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Obesity and the Respiratory System

• Greater frequency of exercise-induced
  bronchospasm
• Overweight infants have more URTIs
• Reduction in forced vital capacity and functional
  residual capacity
• This can result in V/Q mismatch during
  ventilation leading to hypoxemia
• Obese children also have reduced diffusing
  capacity and increased WOB

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Obesity and the Respiratory System

• Morbid obesity and chronic hypoxemia due to V/Q
  mismatch lead to the inability to normalize PaCO2
• Hypersomnolence, polycythemia, pulmonary
  hypertension (/- cor pulmonale), daytime
  hypoxemia and chronic hypercapnia
• Sleep apnea (33 of children with BMI ? 40)
  abnormal sleep patterns and severe oxygen
  desaturation plus central hypoventilation

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Effects of body fat on ventilatory function in
children

• Lazarus et al., Pediatric Pulmonology
  199724187-194
• Australian study using school children aged 9,
  12, and 15 years of age
• Height adjusted FVC and FEV1 versus body fat
• Height and weight adjusted FVC and FEV1 versus
  body fat (body weight takes into account both
  lean and fat mass)

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Effects of body fat on ventilatory function in
children
2.59 2.58
2.57 2.56 2.55
2.54 2.53 2.52
Height Adjusted FVC

• 16 18 20 22 24
  26 28

Percent body fat
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Effects of body fat on ventilatory function in
children
2.61 2.59
2.58 2.56 2.54
2.52 2.51 2.49
Height And Weight Adjusted FVC

• 16 18 20 22 24
  26 28

Percent body fat
Higher proportions of body fat at any given
height and weight are associated with lower
levels of ventilatory function
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Obstructive sleep apnea

• OSA- hypersomnolence, loud snoring, apnea and
  hypoapnea during sleep
• Physiologic changes
• Arterial hypoxemia
• Polycythemia
• Arterial Hypercarbia
• HTN
• Pulmonary hypertension

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Obesity and OSA

• Using overnight oximetry to plan for
  adenotonsillectomy in children with OSA (Nixon et
  al., Pediatrics 2004113e19-e25)
• Effects of OSA are well known and include sleep
  disturbance, lower academic scores, behavioural
  problems, FTT, and cor pulmonale

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McGill Oximetry Scoring System

• 1 normal study/inconclusive for OSA (number of
  SpO2 drops lt 90 was less than 3) recommend
  additional evaluation to rule out OSA
• 2 mild OSA (no. of SpO2 drops lt 90 was ? 3,
  but no. of SpO2 drops lt 85 was ? 3) recommend
  TA waiting list

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McGill Oximetry Scoring System

• 3 moderate OSA (no. of SpO2 drops lt 90 was ? 3
  and no. of SpO2 drops lt 85 was gt 3, but no. of
  SpO2 lt 80 was ? 3) recommend surgery within 2
  weeks
• 4 severe OSA (no. of SpO2 drops lt 90 was ? 3
  and no. of SpO2 drops lt 85 and 80 were both gt
  3) recommend urgent surgery within days

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Obesity and the CVS

• Cardiac disease and atherosclerosis is not
  evident in the pediatric obese population
  increase likelihood of obesity related CVS
  morbidity in adulthood
• Adverse physiologic environment in place raised
  BP, increased CO, poor lipid profile, and
  increased LVH mass

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Obesity and the CVS

• Lower arterial compliance predisposition
  towards HTN
• Increased CO for each kilogram of adipose
  tissue CO increases by 0.1 L/min due to an
  increased stoke volume (risk factor for LVH and
  increased myocardial oxygen needs)

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Obesity and the Endocrine System

• Increased incidence of NIDDM
• Increased incidence of insulin resistance with
  higher levels of cholesterol, low-density
  lipoprotein cholesterol and TGs

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Obesity and the GI system

• Hepatic steatosis
• Abnormal liver enzymes building towards
  cholelithiasis in the future
• GERD and delayed gastric emptying due to
  increased intra-abdominal pressure - risk of
  aspiration ??? Borland et al., J Clin Anesth
  19981095-102 showed no increase in obese
  children
• Maltby et al., Can J Anaesthesia 200451111-5,
  have shown that adult obese patients without
  reflux disease have normal gastric emptying times

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Obesity and Pharmacology

• Most data from adult literature
• Drug distribution is affected by body
  composition, plasma protein binding and regional
  blood flow
• Most obese children have increased lean body mass
  as well as fat the lean mass may account for
  20-40 of excess weight
• This can affect the volume of distribution of
  various drugs
• Renal clearance is increased in adult obesity due
  to increase RBF and GFR

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Obesity and Pharmacology(Brenn Anesthesiology
Clin N Am 200523745-64)

• Thiopental and midazolam are very lipophilic and
  show increased volume of distribution in obese
  patients and dosage should be according to
  patients TBW
• Propofol is a lipophilic drug that does not have
  an increased volume of distribution in obese
  patients and shoud be dosed according to IBW
• NMB agents such as rocuronium and vecuronium and
  morphine should be dosed according to IBW whereas
  Sux and fentanyl should be dosed according to TBW

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Obesity and Anesthetic Outcomes

• Recent study from Pediatric Anesthesia
  200717321-6 by Setzer and Saade looked at
  childhood obesity and anesthetic morbidity
• Retrospective analysis
• 1133 ASA I and II children 2 - 12 years old
  charts were reviewed
• General anesthesia for outpatient dental
  procedures in 2003

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Obesity and Anesthetic Outcomes

• BMIs were calculated and compared to
  international normative data
• Method of induction and perioperative
  complications were noted
• Total of 100 obese (BMI 20.7 - 29.3)and 1033
  nonobese children were compared
• Inhalational induction was used in the vast
  majority of cases (99 vs 99.7)

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Obesity and Anesthetic Outcomes

• Dental procedures were chosen because of the
  reduced systemic physiological impact due to the
  surgery itself therefore adverse events could be
  attributed to anesthesia
• Intraoperative complications included
  laryngospasm, vomiting, and destaturation (SpO2 lt
  85)
• PACU stay was also analyzed for admission, O2
  requirement, and emesis

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Obesity and Anesthetic Outcomes

• Higher incidence of intraoperative oxygen
  desaturation (2 vs 0.19)
• Higher incidence of overnight hospitalization
  due to oxygen desaturation post-op (2 vs 0.19)

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Types of Gastric Bypass Surgeries
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Adolescent Bariatric Surgery

• Cincinnati Childrens Hospital Criteria
• Failure of gt 6 months physician-supervised weight
  loss program
• Physical maturity
• BMI gt 50 or gt 40 with (NIDDM, OSA or pseudotumour
  cerebri)
• Comprehensive team evaluation
• Ability to adhere to nutritional guidelines
• Family support and lifelong follow-up

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Adolescent Bariatric Surgery

• Anesthesia
• Preop consult 1-4 weeks
• First 48 bariatric adolescents, 10 had a
  Mallampati score of 3, but 90 had a Cormack
  grade 1 laryngosopic view after ideal positioning
• Rapid sequence induction

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Adolescent Bariatric Surgery

• Limited data on pharmacokinetics of anesthetic
  drugs
• Drug dosage is approximately 120 ideal body
  weight rather than actual body weight
• Anesthetic vapours low blood-gas soluble agents
  such as desflurane and sevoflurane are ideal for
  bariatric surgery
• Strum et al., demonstrated faster emergence with
  desflurane than sevoflurane (adult population
  BMI ? 35, major abdominal surgery)

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Adolescent Bariatric Surgery

• Post-operatively CPAP and BiPAP is avoided
  immediately due to concerns of anastomotic leak
• PCA analgesia is applied for pain control
  (usually morphine 1 mg with 7 minute lockout and
  no basal rate)

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Summary

• Childhood obesity is an epidemic
• Combination of genetic and environmental risk
  factors
• Management requires a team approach with family
  support and lifelong maintenance
• Anesthetic management issues more research is
  required

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SELECTED BIBLIOGRAPHY

• Kiess W, Reich A, Muller G, Meyer K, Galler A,
  Bennek J, Kratzsch J. (2001). Clinical aspects
  of obesity in childhood and adolescence
  diagnosis, treatment and prevention. Int J
  Obesity 25(Suppl1) S75-S79.
• Feldman W, Beagan BL. (2001). Screening for
  Childhood Obesity. Available www.hc-sc.gc.ca/hppb
  /healthcare/pdf/clinical_preventive/s2c30e.pdf.
  Viewed Oct. 24, 2004.
• Moran R. (1999). Evaluation and treatment of
  childhood obesity. Am Fam Phy. Avalialbe
  www.aafp.org/afp/990215ap/861.html. Viewed Oct.
  18, 2004.
• Hassink S. (2003). Problems in childhood obesity.
  Clin Offi Practice 30(2).
• Shephard RJ. (2004). Role of physician in
  childhood obesity. Clin J Sport Med 14(3)
  161-168.
• Strauss RS. (2002). Childhood obesity. Ped Clin N
  Am 49(1).
• Strauss RS, Must A. (1999). Risks and
  consequences of childhood and adolescent obesity.
  Int J Obesity 23(Suppl 2) S2-S11.