Ketamin Flashcards
0
Q
Physiochemical characteristics
A
- partially water soluble
- Highly lipid soluble
- Limited use to to unpleasant psychomimetic effects
- Minimal resp depression
- Subanalgesic doses used to reverse opioid tolerance
1
Q
Ketamine characteristics
A
- Produces significant analgesia
- Unpleasant pschycomimetic effects
- Causes dissociative anesthesia
- Low protein binding 12%
. Only intravenous anesthetic with
Low protein binding - Bronchial smooth muscle relaxtant
- High lipid solubility this fast onset
2
Q
pharmacokinetics
A
- high lipid soluability–> fast onset
onset: 30 sec
Duration: 5-10 min
metablized: Liver cp450, norkeketamine is the active metabolite 1/3to 1/5 potency of ketamin, hydoxylated and conjugated into water soluble metabolites - excreted: Urine
3
Q
pharmacodynamics
A
- Inhibits NMDA complex
- air way reflexes are preserved but do not assume that patient
can maintain the airway - eyes stay open, pupils moderatly dilated, nystagmic gaze
- lacrimation+salivation increases (use anticholinergic to limit the
effect) - emergence reaction: 1. what limits the use of it. 2. less in kids
3. combining with benzo reduces this+
increases amnesia
6 effects on:
a. CNS:
i. Increase cerebral vasodilation: increase ICP
Increase in Cerebral blood flow
increase in Cerebral o2 use
lowers seizure treshhold/ Do not
use in patient with seizureii. CVS: stimulates sympathetic NS
. causes transient increase in HR, BP and CO
. This leads to increased work of heart and o2 use
. Can be blunted by co-admin of benzo, opioid or gas
Ketamine by itself is myocardial DEPRESSANT
. In conditions that cause depletion of catacholamines
e.g. acute cocaine toxicity or defibrillator placement
ketamine will be myocardial depressant
. The depressant effect of ketamine is usually masked
by stimulation of sympathetic nervous system, however
the depressant activity will manifest in critically ill
patients with limited ability to increase SNS
iii. Respiratory effect: Minimal
. especially when used as a sole agent
. Rapid injection of large dose can cause apnea and
hypoventilation
. maintenance of upper airway reflex but don’t assume that
patient can maintain the airway
. Kids: higher chance of laryngospasm due to increase in
secretions
. this can be reduced by pre-medicating with
anticholinergic drugs
.bronchial smooth muscle relaxtant
. good for patients with reactive airway or patients with
bronchoconstriction
4
Q
Advantage in clinical use:
A
- profound analgesia
- minimal respiratory depression
- bronchodilation
- stimulation of SNS
5
Q
Disadvantage in clinical use:
A
- Unpleasant emergence reastion
- increase in salivation and lacrimation
- Myocardial depression in the absence of catacholamines
e. g. in the case of acute cocaine toxicity or defibrilation
6
Q
Dosage
A
Induction: IV: 1-2 mg/kg
IM: 4-6 mg/kg
Maintenance (not common): 15-45 mcg/kg/min+50%-70% nitrous
30-90 mcg/kg/min alone
Analgesia: 3-5 mcg/kg/min
7
Q
Why give benzo with ketamine
A
- Ketamine as a sole agent does not produce amnesia
- reduce or limit unpleasant emergent reaction
- blunt myocardial effects of ketamine: increase in HR, CO, BP
8
Q
Effect on CNS
A
- Cerebral vasodilation
- Increases cerebral blood flow and o2
Consumption - Do NOT use it in patients with
Intracranial pathology and increased
ICP
. This can be blunted by
Maintenance of normocapnia - Considered anticonvulsant used for
Tx of status epileptics
9
Q
Cardiovascular effects
A
1. Can cause significant but transient
Increase in heart rate, cardiac
Output and blood pressure by
Centrally mediated sympathetic
Stimulation
2 it leads to increased o2 consumption
And myocardial work
3 can be blunted with co-admin of
Benzo, opioids and inhalation
A esthetics
4. However without the sympathetic effect ketamine is myocardial depressant
