FRCA Notes

Paediatric Obesity

Paediatric obesity doesn't quite make the curriculum cut, but the page is included due to recent relevant BJA Education articles.

Resources

  • There is no set definition of what constitutes obesity in childhood, although the WHO's criteria are:
Age Overweight Obese
0-5yrs BMI >2SD above median BMI >3SD above median
5-19yrs BMI >1SD above median BMI >2SD above median

  • Usually multifactorial, including:
    • Excessive caloric intake
    • Physical inactivity
    • Exposure to 'obesogenic' enivronments e.g. calorie-dense, large portioned food
    • Low socioeconomic class
    • Genetic factors

Secondary causes of obesity

Aetiology Examples
Genetic MC4R deficiency
POMC deficiency
Leptin deficiency
Iatrogenic Antidepressants
Steroids
Anti-epileptics
Syndromes Prader-Willi
Beckwith–Wiedemann
Fragile X
Endocrine Hypothyroidism
 Pseudohypoparathyroidism
Hypercortisolism
Growth hormone deficiency
Neurological Brain injury
 Hypothalamic dysfunction
Neoplasms
Psychiatric Anxiety
Depression
Eating disorders


Respiratory

  • OSA/sleep-disordered breathing (2x increased risk)
  • Impaired respiratory mechanics, including FRC, ERV, FEV & FVC and chest wall compliance
  • Asthma (1.7x increased risk) and severity of asthma
  • Atelectasis and respiratory infections

Cardiovascular

  • Hypertension (2x increased risk)
  • Structural heart changes: left ventricular hypertrophy, increase atrial and ventricular size, ventricular dysfunction
  • Cor pulmonale
  • Metabolic syndrome

Gastrointestinal

  • NAFLD
  • GORD (1.8x increase risk)

Endocrine

  • Insulin resistance
  • T2DM (27x increased risk)

Perioperative management of the obese paediatric patient


  • Obese children have a high likelihood of experiencing a critical event in the perioperative period
  • Specialty input if secondary cause for obesity suspected, with investigations such as:
    • HbA1c / fasting glucose
    • TFTs
    • LFTs
    • Lipids
    • Vitamin D
    • ECG
  • Consider sleep studies in patients with obesity presenting for adenotonsillectomy
  • Caution with sedative anxiolytics in those with sleep-disordered breathing

Induction technique

  • Consider decompressing stomach with NG tube if possible
  • May be preferential to obtain IV access rather than gas induction due to higher rates of oxygen desaturation, difficult mask ventilation, airway obstruction and asthma
  • Increased difficulty of facemask ventilation (3.7%) vs. non-obese patients (0.6%)
  • Increased upper airway adiposity can cause macroglossia however obesity itself not an independent risk factor for difficult intubation
  • Optimally position prior to laryngoscopy
  • RSI may be preferable although GORD in relation to obesity not necessarily associated with reduced gatric emptying

Positioning

  • Appropriate positioning and pressure care
  • The physiological changes associated with intra-operative positioning are often amplified in the obese patient e.g. effects on respiratory mechanics due to moving abdominal contents

Pharmacokinetics

  • Increased volume of distribution for lipophilic drugs
  • Increased CYP2D6 activity (opioid metabolism)
  • Increased absolute renal clearance
Use TBW Use IBW Use ABW
Atropine
Glycopyrrolate		 Propofol (induction)
Ketamine		 Propofol (infusion)
Dexamethasone
Ondansetron		 Morphine Fentanyl
Remifentanil
Alfentanil
Suxamethonium Non-depolarising NMBA Paracetamol
Ibuprofen
Penicillins
Cephalosporins		 Local anaesthetics Gentamicin
Sugammadex
Neostigmine		 Adrenaline
Phenylephrine


  • Higher risk of VTE
    • Early mobilisation
    • Mechanical VTE prophylaxis
    • Chemical VTE prophylaxis may be indicated if there are additional risk factors e.g. smoking, use of contraceptive pill
    • Enoxaparin is based on total body weight

  • Multi-modal, opioid-sparing analgesia to reduce risk of opioid-induced ventilatory inhibition
  • Multi-modal anti-emesis

  • May warrant longer PACU stay or HDU care, even in the absence of OSA, given higher incidence of respiratory complications
  • Obesity alone, however, is not necessarily a contraindication to day-case surgery