G. S. P. Panesar, N. Canchi-Murali

Birmingham Children's Hospital, UK


A 9 year old patient with propionic acidaemia was scheduled for scoliosis correction requiring intraoperative nerve monitoring (IONM). Propionic acidaemia precludes the use of propofol based TIVA, whereas volatile anaesthesia impacts  IONM - diminishing both somatosensory and motor evoked potentials. Providing anaesthesia for this specific scenario posed a quandary, mandating a novel anaesthetic approach.


Propionic acidaemia is a rare, autosomal recessive inborn error of metabolism affecting around 1/100,000 individuals. Mutations in PCCA/B genes result in malfunctioning propionyl-CoA carboxylase, an enzyme required to transform amino acids into cellular fuel. Accumulation of propionic acid and its derivatives results in mitochondrial dysfunction, which is responsible for the wide symptomatology seen in this condition. Most pertinent to the anaesthetist are risks of severe metabolic decompensation, centred around ketoacidosis, lactic acidosis, and hyperammonaemia. End organ dysfunction, particularly arrhythmogenic cardiomyopathies and neurological/cognitive impairment are common. Patients are intolerant of prolonged fasting due to catabolism and the release of substrates that are metabolised to propionic acid [1] [2]

Using propofol by infusion is contraindicated as a proportion of the lipid present in emulsion is metabolised to propionic acid. This juxtaposition of surgical requirements and anaesthetic technique required lateral thinking and MDT input in order to determine a safe anaesthetic strategy. We consulted our local metabolic medicine team and experienced departmental colleagues, in combination with literature and case review to determine a safe anaesthesia approach. An open, frank discussion was held with parents regarding proceeding with surgery using this non-standard mode of anaesthesia.

Induction and maintenance

Following minimal fasting, supplemented with IV glucose, anaesthesia was induced using a small bolus of propofol and sevoflurane. The trachea was intubated without the use of muscle relaxant and invasive lines sited. Near infrared spectroscopy and depth of anaesthesia monitors were applied (SedLine, Masimo) in addition to IONM as required by physiologists. Anaesthesia was maintained using:

Remifentanil: 0.2-0.5 mcg/kg/min

Midazolam: 0.5-1mcg/kg/min

Ketamine: 0.2-0.5 mg/kg/hr

Dexmedetomidine: 0.3-0.8 mcg/kg/hr

Lignocaine: 0.5-1mg/kg/hr


SedLine values did not rise above 50 (target 25 - 50) correlating with EEG density spectrum array.  Lactate and ammonia levels, both markers of metabolic decompensation, remained within normal ranges. IONM signalling was preserved, and interpretable by physiologists.

Post procedure

Following PICU admission, weaning, extubation and ward transfer were completed in 24 hours. Ongoing management was led by metabolic medicine and surgical teams who noted no metabolic sequelae postoperatively.

Learning for others

Metabolic conditions present significant anaesthetic challenges : an awareness of the disorder and its implications for general perioperative conduct, specific pharmacological nuances and surgical implications are essential

TIVA does not mandate propofol TCI : anaesthetists should be prepared to adapt techniques and provide a stable physiological and pharmacological environment to facilitate specific procedural requirements and inform accurate surgical guidance.


[1] Orphan Anaesthesia - Anaesthesia recommendations for Propionic Acidemia. Accessed at https://www.orphananesthesia.eu/de/erkrankungen/handlungsempfehlungen/propionazid%C3%A4mie/1750-propionic-acidemia-1/file.html

[2] British Inherited Metabolic Disease Metabolic Disease Group : Propionic Acidaemia. Accessed at https://www.bimdg.org.uk/store/guidelines/ER-PA-v4_887167_09092016.pdf

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