Emergency Treatment of Seizures Flashcards
The emergency treatment of seizures encompasses: (3)
The treatment of any underlying causes;
Preventing systemic complications by maintaining adequate vital functions (as detailed in last week’s session on head trauma);
Stopping the seizure activity while limiting side effects of the treatment.
Emergency treatment of seizures should be initiated in cases of what seizure types? (2)
Cluster
Status Epilepticus
Define cluster seizures
More than one seizure over a 24 hour period.
Define status epilepticus
Continuous seizure activity for >5 mins or recurrent seizures without recovery in between.
Before we discuss stopping seizures with AED, consider how you will control the systemic effects of seizure activity. For each of the following categories, what actions would you consider taking?
Airway?
Intubate if needed
Before we discuss stopping seizures with AED, consider how you will control the systemic effects of seizure activity. For each of the following categories, what actions would you consider taking?
Breathing?
O2 if needed
Before we discuss stopping seizures with AED, consider how you will control the systemic effects of seizure activity. For each of the following categories, what actions would you consider taking?
Circulation
IVFT 2-3 ml/kg/hr
Before we discuss stopping seizures with AED, consider how you will control the systemic effects of seizure activity. For each of the following categories, what actions would you consider taking?
Temperature
Active cooling - STOP at 39C
What class of drugs are used for the immediate control of seizures?
Benzodiazepines
Before we discuss stopping seizures with AED, consider how you will control the systemic effects of seizure activity. For each of the following categories, what actions would you consider taking?
Monitoring? (4)
HR
RR
Peripheral pulses
Temp
Immediate control of seizures:
What dose of diazepam? (2)
Bolus of 0.5 to 1 mg/kg intravenously (IV)
1 to 2 mg/kg rectally.
How does diazepam work in the immediate control of seizures?
Diazepam acts by increasing the inhibitory post-synaptic potential which increases seizure threshold and thus inhibits the spread of seizures.
Immediate control of seizures:
What dose of midazolam? (2)
Bolus of 0.2 mg/kg IV, intramuscularly (IM) or subcutaneously (SC).
How many times can you repeat diazepam/midazolam in immediate control of seizures?
2-3 times
In patients not currently on medication and with no known liver pathology, what remains the AED of choice for its efficacy.
phenobarbitone
If the patient is naïve to the AED, an initial dose of phenobarbitone?
3 mg/kg IV/IM or orally (PO) every 12 hours should be administered.
Should the patient experience another seizure before the next dose is due or if the patient is in SE. What dose of phenobarbitone should be considered?
Loading dose
(18 – 24 mg/kg within 24 hours (18 mg/kg in cats) ideally administered by boluses of 3 mg/kg every 30 minutes. The speed of loading is dictated by the severity of the episodes and the patient’s cardiovascular parameters.)
How long before repeated doses of phenobarbitone?
20 mins
Side efects of phenobarbitone? (5)
Sedation
Ataxia
PD
PU
Polyphagia
In dogs already on phenobarbitone, an additional dose of ? can be considered but blood levels will be required to decide changes in oral dosage
6 mg/kg IV/IM/PO
Before am additional dose pf phenobarbitone what should be taken?
Bloods
Levetiracetam; dosing schedule?
TID
Levetiracetam; licensed?
No
Levetiracetam; half life?
Short
When would Levetiracetam be the IV tx of choice? (3)
-Less cardio-vasc stable
- Co morbidity
- Liver Dx
How does maintenance dose of Levetiracetam change when given with phenobarbitone?
he maintenance dose of levetiracetam is around 20 - 30 mg/kg every 8 hours which should be increased to 30 - 40 mg/kg every 8hrs
Potassium bromide; half life?
Very long
Potassium bromide; when is steady state achieved?
3mo
Side effects of Potassium bromide in the loading period? (3)
Sedation
Ataxia
V+
When to use Potassium bromide in cats?
DO NOT
Imepitoin; how does this work as an AED?
It partially activates the receptors for the neurotransmitter GABA in the brain
Seizure rates with imepitoin vs phenobarbitone?
Higher with imepitoin
This drug can be given intravenously in an emergency situation and is not metabolised by the liver.
Levetiracetam
The intravenous loading dose of this drug must be given cautiously as it may cause cerebral depression, respiratory depression, and hypotension.
Phenobarbitone
This drug is not available as an injection formulation and does not cause increases in liver enzyme activity.
Imepitoin
This drug is not available as an injectable formulation and takes around three months to reach a steady state in the blood
KBr
If despite administration of benzodiazepine and AED drug loading there is an inability to control the seizures, whats next?
CRI; then last resort inhalation
Aim of CRI with seizures?
Allow seizure control while continuing to administer anti-epileptic drugs.
How long should a seizuring dog be on CRI? When to reduce?
Once the infusion has started it should be maintained for at least six hours and if no seizures are identified it should be gradually decreased over another six hours.
What happens if a CRI is abruptly stopped?
Loss of seizure control
What can be used in the CRI? (3)
DIazepam
Midazolam
Propofol
CRI of diazepam:
How to reduce dose?
Reduced by 50% every six hours to avoid withdrawal seizures.
What equipment to give CRI of diazepam and why?
It must also be protected from?
Diazepam binds to plastic, a syringe driver and non-plastic syringes are required, or the giving set and syringes should be flushed with diazepam first. It should be protected from direct light.
When to use propofol CRI?
A propofol CRI could be started alongside a diazepam or midazolam CRI should the seizures continue. This will allow for a lower quantity of propofol to administered than if it was administered alone.
What is the aim with a propofol CRI?
stop in the seizure activity but should still allow the patient to ventilate spontaneously with a normal SpO2 >95 mmHg.
DO NOT USE PROPOFLO PLUS for CRI; why?
it contains a preservative (benzyl alcohol) which will become toxic if administered for longer durations.
If a patient is refractory to CRI - what next?
Induce GA - propofol to iso/sevo
If GA has to be induced to control seizures - prognosis?
Guarded
With seziures; If possible, a blood sample should be taken for exclusion of ?
Metabolic vs toxic causes
Before commencing tx in a seizuring patient; why take bloods if a patient is on AED?
serum levels of the drug should be taken prior to increasing the dose. Such levels are available for phenobarbitone, potassium bromide and levetiracetam.
How often should routine bloods for phenobarbitone and KBr be performed?
At least twice a year
With a loading dose; when should serum bloods be taken?
After loading done
After starting on maintainance dose; when should bloods be taken for :
A) Phenobarb?
B) KBr?
2-3 weeks for phenobarb
3mo KBr
Why care with sea swimmers and KBr?
There can be increased clearance of potassium bromide due to increase salt uptake
What can be responsible for breakthrough in seizure control? (2)
Inadequate blood
Inadequate therapy
What about the liver can increase clearance of phenobarb?
Hepatic induction associated with phenobarbitone administration can result in increased clearance of the drug
What OTHER causes may effect blood levels of AED? (2)
Drug interaction
Intestinal malabsorption
What can CAUSE inability to control an episode of seizures?
- New condition
- Incorrect diagnosis
Seizures in the six months following a traumatic brain injury have been reported in around ?% of dogs
6.8
Seizures in the six months following a traumatic brain injury have been reported in around ?% of cats
5.6
TBI patients will commonly require ongoing AED therapy and some of them may become refractory in case of large areas of tissue necrosis causing
hydrocephalus ex-vacuo.
Define hydrocephalus ex-vacuo.
ventricular enlargement as a consequence of loss of brain parenchyma.
