Post on 25-Dec-2015
Perioperative seizures
Dr. S. Parthasarathy MD., DA., DNB, MD (Acu),
Dip. Diab.DCA, Dip. Software statistics- Phd
Mahatma Gandhi Medical college and research institute , puducherry , India
Definition • A seizure can be defined as the clinical manifestation of
an abnormal and excessive discharge of neurones, seen
as alteration of consciousness, motor, sensory or
autonomic events.
• Epilepsy is defined as recurrent (two or more) epileptic
seizures unprovoked by any immediately identifiable cause.
• Epilepsy includes seizures but seizures ??
Incidence
• Only epilepsy – incidence • 0.5 – 1 %
• But peri operative seizures – incidence ??
• EEG monitoring in potential patients ?? • It can also miss ??
How does it relate to us ??
• Sudden seizures – periop• Epilepsy – anaesthetic considerations• ICU status epilepticus
Clinical setting
• Commonest setting
• LA toxicity
• Intercostal • IVRA • Cervical plexus • Epidural then others
Test dose
• There may be premonitory symptoms, such as peri oral
tingling, or feelings of dissociation following a test dose.
• Epinephrine ??
• Catheter malfunction
• Catheter position change
• Axillary ??
• Field blocks
Maximum dose for infiltration (mg/kg)
• Lidocaine 3 - 4• With adrenaline 7• Bupivicaine 2• With adrenaline 3• Prilocaine 6• With adrenaline/octapressin 8• Additive
What Type of Surgery Places the Patient at Risk for Seizures?
• Neuro surgery 20 %
• Leave alone head injury • Supratentorial tumors • Cerebral abscess 90 % • Drainage 15 – 20 %
• Preop seizure history -- incidence is very much higher
Other surgeries
• extensive bowel surgeries • Burns and plastic surgeries • Gut obstruction
• Fluid shifts – seizures
Hyponatremia – usually 115 is cut off
• TURP syndrome • Extensive bowel surgeries • Other scopies where irrigation is done • Plastic and burn reconstruction – massive fluid shifts • Drugs like diuretics • Water intoxication • SIADH. Vomiting • Renal and hepatic disorders
Hypocalcemia
• Low albumin; • abnormal acid-base status and electrolytes; • drugs used during the peri-operative period• transfusion of large volumes of citrated blood; • Parathyroid surgeries ,thyroid , CPBs• Sepsis , CRF • Calcium chelators in radiographic contrast
In pregnant – other than
• Epilepsy, eclampsia, drugs
• Posterior reversible encephalopathy • Amniotic fluid embolism • Cortical vein thrombosis
In an ICU
• Seizures
• Posttraumatic brain injury• CNS infections• Endocrine and metabolic disorders• Drugs or toxins
Seizure prone electrolyte disturbances
• Hyponatremia• Hypokalemia• Hypocalcemia• Hypoglycemia and hyperglycemia• Hypomagnesemia
Drugs
• Amphetamine • SSRIs • Tricyclics • Levodopa • Deriphyllin • Phencyclidine • Withdrawal of antiepileptics• Methergin
Anesthesia related
• Tramadol Pethidine ,• etomidate • Enflurane ,sevo • Atracurium• Flumezanil
• Ketamine methohexital ??, propofol • Hypocapnia ??
Other settings
• Renal failure --- erythropeitin ?? • Hepatic failure • Hypothyroidism • Hashimato s
• Inciting factors • Fever , infection , sleeplessness
Reflex Anoxic Seizures and Anaesthesia
• What is this ?? • ocular pressure, venepuncture, accidental
trauma and fear • Young female school children
• Grand mal like • EEG changes may not be present
What should we do
• Patient Should not fall • Oxygen • Bag and mask • Two IV lines • Glucose • Thiamine • Benzodiazepines
Settings at a glance
• Local anaesthetic toxicity • TURP • Eclampsia • Neuro surgeries • CPBs • Drug intake • Drug withdrawal
Post operative period
• Postoperative generalized shaking is usually because of shivering, which may be thermoregulatory or non-thermoregulatory.
• The latter is thought to be secondary to the
effects of volatile anaesthetics, pain or both.
Pseudoepileptic seizures
• common in the postoperative period. • resemble tonic–clonic seizures • NO abnormal electrical discharges• history of convulsions and/or psychosomatic illness. • flamboyant, last longer than 90 s , asynchronous limb
movements, side-to-side head movements, closed eyes (including a resistance to eye opening).
• There is no cyanosis or post-ictal period• may be incontinence or tongue-biting. • Seizures may settle with reassurance. • Plasma prolactin concentrations tend to be raised after epileptic
seizures and normal after pseudo-seizures.
In fits • Case ?? • Massive fluid shifts• Epileptic • Systemic illness • Drugs, alcohol • Hypoxemia • Electrolytes , blood glucose, RFT, LFT • CT brain • Oxygenation, benzodiazepines
Status epilepticus
• The traditional definition of status epilepticus as a seizure
lasting or recurring without regaining of consciousness over a
30 min period is primarily useful for epidemiological
purposes.
• Can we wait for 30 minutes ??
• In clinical practice, most convulsive seizures abate within 2–3
min and a seizure that continues for more than 5 min has a
low chance of terminating spontaneously.
Physiological changes • Increased cerebral metabolism • Increased blood flow, • increased glucose and lactate concentration• Increased catecholamine secretion
• 30 – 60 minutes
• hyponatraemia, potassium imbalance,• evolving metabolic acidosis, consumptive
coagulopathy, rhabdomyolysis, and multi-organ• failure
Stages
• Premonitory (0 -5 min) • Early (5-10 minutes) • Established ( 10 – 30 minutes )• Refractory ( 30 – 60 minutes)
Refractory status (30–60 min)
• Refractory CSE (RSE), where SE continues in spite of administration of two AEDs (e.g. benzodiazepines and phenytoin), is associated with a high risk of complications.
• These include tachyarrhythmias, pulmonary oedema, hyperthermia, rhabdomyolysis, and aspiration pneumonia.
To continue till ??
• Maximal therapy should be maintained until
12–24 h after the last clinical or electrographic
seizure, after which the dose should be
tapered. If seizures recur, therapy can be re-
instituted or altered