Bariatric patients, PICU SOP

Reduced functional residual capacity → Increased risk of desaturation during induction of anaesthesia

• Pre-oxygenate as tolerated (face mask, high flow nasal cannula, or non-invasive ventilation)
• Use a RAMP position with either bedside pillows or an Oxford HELP pillow to minimise diaphragmatic splinting

Higher intra-abdominal pressures → Increased risk of aspiration

• Gastric transit times may be longer and true fasting status may never be achieved
• Consider decompression of the stomach with a nasogastric tube and continual aspiration

More adipose in upper airway soft tissues → Airway obstruction occurs early following induction of anaesthesia

• Watch for signs of obstruction with face mask ventilation
• Beware of insufflating the stomach

FACE MASK VENTILATION = MORE DIFFICULT

Always use an oropharyngeal (Guedel) airway plus a 2-hand 2-person technique as standard

SUPRAGLOTTIC AIRWAY INSERTION = MORE DIFFUCLT

Use a second generation supraglottic airway device such as an iGEL (sized based on total body weight)

INTUBATION = NOT MORE DIFFICULT

Incidence of difficult intubation is not more common; however, have a low threshold for video laryngoscopy

Reduced lung compliance → Higher ventilatory pressures with greater risk of barotrauma

• Target a higher PEEP to encourage alveolar recruitment and prevent basal collapse / avoid atelectasis
• Aim for lung protective ventilation (6-8ml/kg based on ideal body weight)
• Use a pressure control mode of ventilation to avoid barotrauma 
• Consider iatrogenic pneumothorax if patient deteriorates on the ventilator
• Spontaneously ventilating patients will need higher levels of pressure support
• Consider transpulmonary pressure monitoring if high ventilatory pressures are a persisting concern
• Be aware that there is an associated higher incidence of bronchospasm in obese children
• Consider echocardiography to evaluate for right heart failure if failing to wean from ventilator
• Consider extubating onto NIV if features in history concerning for obstructive sleep apnoea  

As a rule, never exceed maximum adult doses when prescribing for children. Please refer to the Society of Obesity and Bariatric Anaesthesia (SOBA) paediatric guidelines for more information.

Total body weight (TBW)

Actual measured body weight in kilograms (kg)

Ideal body weight (IBW)

BMI₅₀ x height (m)²    

where BMI₅₀ = age and sex specific BMI at 50^th centile

Adjusted body weight (AdjBW)

IBW + 0.35 x (TBW – IBW)

Commonly used drugs in PICU and appropriate dosing strategies

For ongoing management in PICU, refer to the adolescent handbook for all children above 50kg (located at PICU staff base 2). For bariatric children below 50kg seek expert pharmacy advice or use best clinical judgment.

Propofol → Propofol Related Infusion Syndrome (PRIS)

• Profound bradycardia → Asystole in the presence of metabolic acidosis, rhabdomyolysis, or hyperlipidaemia
• Children are at higher risk of PRIS due to relatively lower glycogen stores and dependence on fat metabolism
• Do not exceed propofol infusion rates of 4mg/kg/hr
• Do not exceed 48hrs of continuous infusion unless documented PICU consultant authorisation
• Prevention / management
  • Monitor lactate at least 12 hourly. Monitor creatine kinase and triglyceride levels daily after 48 hours of propofol infusion.
  • If any unexplained rise in lactate, CK or triglycerides STOP PROPOFOL IMMEDIATELY and inform PICU Consultant.
  • Avoid propofol in patients with relatively low carbohydrate to high lipid intake (e.g., consider starting glucose infusion and stopping lipid component of parenteral nutrition)
  • Stop propofol and start alternative sedative agents (e.g., morphine and midazolam/clonidine/dexmedetomidine)
  • If propofol must be continued >48hrs for clinical reasons, cycle off propofol for 12 hours every 48 hours.
  • Provide cardiovascular and renal support as required

Dexmedetomidine → Bradycardia, hyperthermia

• Highly selective alpha-2 adrenoreceptor agonist frequently used to reduce delirium and facilitate extubation
• Do not exceed dexmedetomidine infusion rates of 1.4mcg/kg/hr (dose based on ideal body weight)
• All bariatric patients on
• Risks include bradycardia and hypotension
• Discontinuation syndrome can occur (reflex tachycardia and hypertension)
• There is an established association with hyperthermia – this risk may be greater in bariatric patients.
• NB: Clonidine may also interfere with thermoregulation although the risk is probably less than with dexmedetomidine.
• All patients on alpha-2 adrenoceptor agonist infusions must receive continuous core temperature monitoring.

• Energy requirements for the bariatric child in critical care are calculated based on ideal body weight, consider liaising with adult dietetics for additional guidance
• Blood glucose monitoring is required for these children as they have a higher risk of insulin resistance and type 2 diabetes mellitus (may be precipitated by critical illness or high dose steroids in intensive care) 
• Pressure care Always conduct a risk assessment and follow NHS GGC guidance
• Non-invasive blood pressure cuffs must be sized appropriately – cuffs that are too small will overestimate blood pressure and cuffs that are too big will underestimate blood pressure
• Manual handling Always follow NHS GGC guidance and local manual handling training. Standard approach for bariatric children is to use a PAT slide with a glide sheet; however, use a hover mattress if weight >90kg (may be available from adult critical care)
• Early mobilisation is essential for any bariatric child receiving intensive care.
• Adequate hydration Repeat clinical assessment may be required as calculated fluid requirements may not be accurate at extremes of weight
• Venous thromboembolism (VTE) prophylaxis
  • Always perform a risk assessment and check NHS GGC guidance
  • Anti-thrombotic stockings if >40g
  • Consider prophylactic LMWH but obesity alone is not an indication if <16 years
  • Seek specialist haematology advice if unsure

When well enough, all bariatric inpatients should be assessed by a Paediatric Dietitian, Physiotherapist (+/- Occupational Therapist) to develop a weight management plan before discharge. Clinical Psychology assessment may be useful if behavioural or mental health concerns are a factor. Special consideration should be given to children with hyperphagic behaviours (e.g. Prader-Willi Syndrome, ROHHAD syndrome) – these children should be assessed by Paediatric Endocrinology and CAMHS.

Following discharge all bariatric children should be followed up with their GP for lifestyle and dietary interventions to reduce their risk of future complications arising from obesity.