Serotonin Syndrome Flashcards
Serotonin Syndrome incidence and epidemiology
incidence unknown due to lack of data
some evidence for mild cases being self limiting
Occurs across all age groups
Of those overdosing on SSRI, SS is in 15% of those cases
Serotonin Syndrome Symptomatology triad
- Altered mental status
Maybe presenting as anxiety, agitation, confusion
- Neuromuscular abnormalities
Muscle rigidity, hyperkinesis, hyper reflexivity
- Autonomic hyperactivity
Diaphoresis, tachycardia, HTN, N/V/D
Serotonin Syndrome clinical findings spectrum
Akathisia to hyperthermia
most common ddx (2)
anticholinergic toxicity
malignant hyperthermia
Serotonin Syndrome sx and distinguishing factors
Clonus
Hyperreflexia
Mydriasis
Diaphoresis
Tachycardia
Tachypnea
Agitation, delirium
Anticholinergic Toxicity sx and distinguishing factors
Dry mouth
Urinary retention, decreased bowel sounds
Mydriasis, blurry vision
Fever
Agitation, delirium, hallucinations
Malignant Hyperthermia sx and distinguishing factors
from a volatile anesthetic
During or after surgery
Hyperthermia
Tachycardia
Acidosis
Muscle rigidity
Rhabdomyolysis
DDX differences between SS AND
-anticholinergic toxicity
-malignant hyperthermia
-NMS
- Anticholinergic toxicity
No neuromuscular abnormalities or diaphoresis - Malignant hyperthermia
Anesthetic agents primarily
Does not have HYPER reflexia - NMS
Dopaminergic agent
Days to wk vs SS which is abrupt
Prolonged vs SS which is rapidly resolved
Vitals similar
NMS would have lab results like ELEVATED CK, LFT, WBC, Low Fe while SS does not
NMS is hyporeflexia vs SS which is hyper
Hunter serotonin toxicity criteria
MOST ACCURATE
Presence of a serotonergic agent AND
spontaneous clonus
then
inducible clonus + agitation OR diaphoresis
then
ocular clonus + agitation OR diaphoresis
then
tremor + hyperreflexia
then
hypertonic + temp >38 + ocular clonus or inducible clonus
sternbach criteria for SS
addition or inc of a serotonergic agent and 3 or more features on a list and told to r/o other etiologies listed
serotonin syndrome patho
5HT effects CNS and PNS
- In CNS it modulates behavior and thermoregulation
- In PNS it modulates GI motility, broncho, uterine
- Mult families of 5HT receptors that mediate
-Stimulation of 1a and 2a associated with SS but no 1 receptor is associated
-Can be antag or agonist - Mult mechanisms
-Inc L tryptophan means inc 5HT
-MAOI causes inc presynaptic 5HT which leads to inc 5HT
-Inc 5HT release
-Direct or indirect 5HT receptor agonist
1A
-Direct or indirect 5HT receptor antagonist
2A - How does it play out
o Inc 5HT means inc NE
-Mult responses from that in chart listed
inc in 5HT synthesis causes
tryptophan
inhibition of 5HT metabolism causes
MAOI
NDRI
St johns wort
inc 5HT release causes
amphetamines
dextromethorphan
NMDA/cocaine
5HT1 receptor activation causes
triptans
opiates
mirtazapine/trazodone
lithium
ergot derivatives
NDRI
LSD
5HT2A receptor antagonism rx class
SGA
5HT Synaptic cleft uptake inhibition causes
SSRI
SNRI
TCA
NMDA/cocaine
inc in 5HT receptor activation leads to
inc NE release
inc NE release leads to
uncoupling of oxidative phosphorylation
—-inc thermogenesis
inc skeletal muscle activity
—-inc thermogenesis, muscle rigidity, clonus, hyperreflexia, tremor
vasoconstriction
—-inc heat dissipation
—-inc BP
autonomic instability
—-diaphoresis, inc HR, inc BP, N/V/D
What feature distinguishes SS and NMS?
- NMS has an abrupt time to onset.
- Patients with SS will likely demonstrate deviation in lab values, including CK, LFTs, and WBC.
- Patients with SS exhibit hyperreflexia and lower extremity rigidity, a contrast to the hyporeflexia seen in NMS.
- Tachycardia and hyperthermia are more common with SS.
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The increased 5-HT receptor activation seen with serotonin syndrome leads to
- An increase in norepinephrine and vasodilation.
- Vasoconstriction and autonomic instability.
- A decrease in norepinephrine and uncoupling of oxidative phosphorylation.
- Autonomic instability and decreased skeletal muscle activity.
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How do antidepressants cause SS
Mechanism: overstimulation of serotonin receptors; dose-related
Risk Factors: concomitant serotonergic agents
most cited and implicative agents
triptans and SS warning
d/c
linezolid and SS warning
monitor
use only if no other therapies available
Which of the following correctly pairs the agent with its mechanism in serotonin syndrome?
- Tryptophan inhibits 5-HT uptake from the synaptic cleft.
- SSRIs increase 5-HT synthesis.
- Opiates inhibit 5-HT metabolism.
- Triptans activate 5HT-1B and 5HT-1D receptors.
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Tx of SS MILD
d/c offending agent
supportive care
BZD
Tx of SS Moderate
Consider 5HT2A ANTAG
Aggressively correct cardiorespiratory and thermal abnormalities
Tx of SS severe
Sedation
Neuromuscular paralysis
Intubation
supportive care for SS
SpO2 >94
volume resuscitation
vital sign correction
continuous cardiac monitoring
BZD and SS
essential regardless of severity
controls agitation and blunts adrenergic response
Diazepam 5-10mg IV q8-10 min
Lorazepam 2-4mg IV q8-10 min
Cyproheptadine and SS
5HT-2A receptor antagonist
initial: 12mg once then 2mg every 2 hrs until clinical response
PRN : 4-8mg q 6hrs
Key components of the treatment of serotonin syndrome include?
- Benzodiazepine administration for agitation.
- Supportive measures to maintain vital signs.
- Cyptoheptadine should be considered for patients with cardiac, respiratory, or thermal abnormalities.
- All of the above.
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