Childhood Obesity: Anesthetic Implications The Changing Practice of - - PDF document

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Childhood Obesity: Anesthetic Implications

Marla Ferschl, MD Associate Professor of Anesthesia University of California-San Francisco

The Changing Practice of Anesthesia 2015 UCSF Department of Anesthesia and Perioperative Care September 25, 2014

Disclosures

• None

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Overview

• Definition
• Pathophysiology
• Comorbid Conditions
• Anesthetic Implications

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Case Scenario

• 6 year old male weighing 55kg presents for

adenotonsillectomy in the setting of OSA How do you:

1. Manage his airway 2. Dose Medications 3. Ensure a safe yet rapid emergence 4. Provide adequate post-operative pain control

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Obesity-Definition

• You know it when you see it!

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Obesity-Definition

• Adults:

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Obesity-Definition

• Childhood BMI

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>85%ile=overweight >95%ile=obese Rough estimate: BMI>20 in age 2-5 BMI>25 in age 6-12

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Obesity Prevalence

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Health, United States, 2004. U.S. Department of Health and Human Services.

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Ogden et al. JAMA 2014

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Obesity-Pathophysiology

• 90% from excess calorie consumption
• 10% secondary to endocrine disorders,

neurological conditions, and syndromes

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Co-Morbid Conditions

• OSA

– 13-59% of overweight children – Diagnosed by parent hx or sleep study

• Mild
• Moderate
• Severe

– Diminished ventilatory response to CO2

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Co-Morbid Conditions

• Pulmonary

– Decreased FRC, FEV1 and DLCO – Asthma

• 30% of obese 8-18 year-olds have

asthma

• Higher BMI correlates with higher severity

– More frequent URIs

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Lang JE et al. J Asthma 2009. Jedrychowski et al. Public Health 1998. Li AM et al. Arch Dis Child 2003.

Co-Morbid Conditions

• Cardiovascular

– 20-30% incidence of HTN – Obese children have increased blood volume and stroke volume increased cardiac output – LVH, hypercholesterolemia and hyperlipidemia

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Co-Morbid Conditions

• Type 2 Diabetes

– Metabolic syndrome common – 24% progress to DM within 2 years – 45% of pediatric patients with Diabetes are Type 2!!!

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Gidding SS et al. J Pediatr 2004 Craig ME et al. Pediart Diabetes 2009

Anesthetic Implications

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Increased relative risk of:

• Difficult mask ventilation
• Airway obstruction
• Desaturation
• Bronchospasm

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Anesthetic Implications

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Airway Management

• More difficult mask ventilation

– Oral airway and LMA ready

• Meticulous patient positioning

– Ramp

• Back-up plan if conventional DL fails

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Pharmacology

• How do you know how much to give?
• Total Body Weight

>>

• Lean Body Weight

– =IBW +0.3 x (TBW-IBW)

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• Ideal Body Weight

– =50% BMI x height (meters2)

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Pharmacology

Age (yr) Weight (Kg) 1 10 3 15 5 20 7 25 10 30

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Approximate Ideal Body Weight by Age

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Pharmacology

• Theoretically:

– Lipophilic drugs have increase volume of distribution – Hydrophilic drugs remain unchanged

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Recommended Dosing Algorithm

Medication Dosing Weight

Thiopental sodium Lean body weight (more rapid awakening) Propofol Lean body weight (induction bolus) Total (actual) body weight (maintenance infusion) Etomidate Lean body weight Succinylcholine Total (actual) body weight Pancuronium Ideal body weight Rocuronium Ideal body weight Vecuronium Ideal body weight Cisatracurium Ideal body weight Fentanyl Lean body weight Alfentanil Lean body weight Remifentanil Lean body weight Midazolam Total (actual) body weight (bolus dose) Ideal body weight (infusion) Paracetamol Lean body weight Neostigmine Total (actual) body weight Sugammadex Total (actual) body weight or ideal body weight + 40% Enoxaparin (VTE prophylaxis) Total (actual) body weight 0.5 mg·kg−1 24

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Pharmacology

• General rule

– Initial dosing to ideal body weight; titrate to effect

• Succinylcholine dosed to Total Body weight
• Highly lipophilic drugs (midazolam, thiopental)

may stick around longer

• Caution with opioids as ventilatory response to

CO2 may be altered

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Emergence and Recovery

• Patients more prone to airway obstruction,

awake extubation

• Caution with opioids in recovery room and for

home

• When in doubt, admit

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Case Discussion

• 6 year old male weighing 55kg presents for

adenotonsillectomy in the setting of OSA

– IV induction unless experienced in inhalational induction – Dose propofol to LBW, muscle relaxants to ideal body weight – Consider Desflurane – Minimize opioids until patient spontaneously ventilating, then titrate to effect – Consider dexmedetomidine to smooth emergence (0.5g-1g/kg) – Awake extubation – Careful post-op observation

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Questions?

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