Respiratory chain, pathologies of the

Mitochondria are the site of many metabolic reactions that are essential for the proper functioning of cells. These are: the respiratory chain (ATP synthesis), the Krebs cycle (pyruvate kinase), the ß-oxidation of fatty acids (SCAD, MCAD, LCAD, VLCAD), and the cycle of urea (ornithine carbamyl transferase).

While in fact any metabolic abnormality of one of these metabolic pathways is strictly speaking a mitochondrial cytopathy or  disease, this term is generally synonymous with pathology of the respiratory chain as Leigh disease, MELAS, MERFF, MNGIE, NARP syndromes.


Anesthetic implications:

The anesthetic considerations summarized in the table below relate essentially to the pathologies of the respiratory chain but are applicable to all mitochondrial diseases.



Preoperative


-         neurological assessment: epilepsy? spasticity? muscular involvement ?

-         cardiological assessment: ECG (conduction), echocardiography

-         metabolic assessment: SGOT, SGPT, renal function, endocrine disorders ?

-         check the blood lactate in basal conditions (venous sampling is OK if no tourniquet is used)

-         swallowing disorders ? GERD ? Central or/and obstructive apnea ?

-         treatment: anti-epileptic drug (s), carnitine supplements

-        avoid elective surgery in case of fever (risk of neurological deterioration?)

Anesthesia

-         short fasting time or glucose-containing infusion as soon as preoperative fasting is started

-         usual dose of carnitine and antiepileptic drug in the morning

-         IV induction (single-dose propofol) or inhalation (sevo)

-         avoid using continuous infusion of propofol: increased risk of PRIS ?  because of the effect of propofol on respiratory chain (factors II and IV) and on the  intramitochondrial transport of long-chain fatty acids

-         IV maintenance: glucose 5% + electrolytes (if possible avoid lactates-containing solutions)

-         monitor: blood glucose and lactates

-         avoid hyper - and hypoventilation
         hyper - and hypothermia

-         avoid succinylcholine if atrophy

-         monitoring of curarization 

-         morphine: risk of decreased response to hypoxia or hypercarbia. Remifentanil ?

-         reliability of the EEG processing methods to assess the depth of anesthesia ?

-         no increased risk of malignant hyperthermia

-         regional anesthesia: 
        - central block: OK if no demyelination
        - difficult if scoliosis
        - peripheral block: OK unless axonal neuropathy is present


PACU  


-         risk of decreased response  to hypoxia or hypercarbia

-         monitor: blood glucose and lactates

-         sometimes important hyperthermia (24-48 h)