Case 31 - Carcinoid syndrome

Question 1

What is carcinoid tumor?

Answer 1

• neuroendocrine tumor
• typically found in appendix, ileum, and rectum; able to metastasize
  
  • can find in lung too
• secrete various bioactive substance: serotonin, histamine, bradykinin, etc.

Question 2

how do you diagnose carcinoid tumor?

Answer 2

• 5-HIAA urine and plasma level
  
  • ​metabolite of serotonin

Imaging studies

• help locate primary tumor
• look for mets

Bronch

• useful for tumors located in bronchial tree

Question 3

patient has diagnosed carcinoid tumor. How does he get carcinoid syndrome?

Answer 3

• although carcinoid tumors secrete bioactive substances, tumors that drain into portal system (like tumors of GI tract) will have these substances metabolized by the liver.
• Tumors that secrete substances that do NOT drain into portal circulation -> bypass hepatic metabolism, and enter systemic circulation –> see bioactive substance effect –> carcinoid syndrome

Liver Mets

• large tumors secrete so much bioactive substance, that overwhelms liver’s ability to inactive it –> released into system circulation = s/sx of carcinoid syndrome

Question 4

What are the clinical featurs of carcinoid syndrome?

Answer 4

s/sx 2/2 to bioactive substance release into circulation

Triggers of sertonin/histamine release:

• stress, exercise, alcohol, coffee
• serotonin rich food - bananas, avocados, eggplant, kiwi

serotonin/histamine effects

• cutaneous flushing
• hypertension vs hypotension
  
  • some substances vasodilate, others vasoconstrict. Labile BP as a result
• diarrhea; n/v
• abdominal pain
• wheezing/bronchospasm

Question 5

Is carcinoid syndrome associated with cardiac abnormalities?

Answer 5

• right side valvular lesions
  
  • tricuspid stenosis or regurg
  • pulmonary stenosis or regurg
  • possibly due to valvulitis and fibroblast proliferation (fibrous tissue and scarring)
• right sided CHF as a result
  
  • hepatomegaly, lower extrem periph edema, JVD
• rare to cause left valvulopathy due to metabolism of bioactive substances by lung
• fibrous tissue growth of electrical pathways –> arrhythmias

Question 6

what is carcinoid crisis?

Answer 6

• life threatening form of carcinoid syndrome
• severe flushing, labile BP, cardiac arrhythmias, bronchoconstrict, mental status change, CV collapse

Pathology

• due to sudden release of excessive amts of tumor mediator substances

Triggers

• anxiety, pain
• hypoxia/hypercarbia
• hypothermia
• tumor manipulation
• catecholamine releasing agents
• histamine releasing agents

Question 7

what is the tx for carcinoid crisis

Answer 7

• due to sudden release of excessive amounts of tumor mediator substances

Tx:

• tell sx to stop manipulating tumor
• IV Fluids
• octreotide
• H1 & H2 receptor blockers
• phenylephrine/vasopressin

Question 8

What are your concerns when a patient with carcinoid shows up to your OR?

Answer 8

1) history and physical for s/sx of carcinoid syndrome

• tells you that tumor mediator substances have access to systemic circulation
• diarrhea, wheezing, heart murmur
• CBC (GI bleeding?), CMP (dehydration, electrolyte derangements), glucose (serotonin causes hyperglycemia)

2) Heart disease - ECHO & EKG

• right side valvular disease –> CHF
  
  • ​valvular lesions 2/2 serotonin induced fibrous tissue growth of valves
  • pulm HTN vs regurg, TR
• fibrous growth of endocardium –> electrical pathways –> arrhythmias

3) diarrhea; N/V

• Dehydration
• metabolic derangements

4) Wheezing/bronchospasm

• responsive to beta 2 agonists?
• need to optimize
  
  • octreotide
  • steroids
  • ipratropium
  • antihistamines

Question 9

What is somatostatin?

Answer 9

• endogenous substance
• inhibits GI motility, gastic acid production, inhibits tumor mediated substance release
• **effective in tx carcinoid crisis**

somatostatin vs octreotide

• octreotide = synthetic analogue of somatostain
  
  • lasts longer, different routes of admin (sub-q, iv injection, continuous infusion)

Question 10

What is your pre-operative management for carcinoid tumor pts?

Answer 10

• Avoid triggering factors that provoke carcinoid crisis.
• correct HD instability, intravascular depletion, bronchospasm, and electrolyte imbalances preoperatively
  
  • ​consider starting octreotide pre-op
• BZD and antihistamine
  
  • anxiety can trigger carcinoid crisis

Lines:

• large bore perpheral IV access
• pre-induction arterial line
  
  • labile BP, triggers of carcinoid crisis can occur with induction and intubation
• CVC
  
  • fluid shifts, vasoactive therapy
• PAC vs TEE
  
  • dependent on presence and extent of cardiac involvement
  • TEE - CO, volume status, valvular pathology

Question 11

is neuraxial anesthesia contraindicated for carcinoid patients?

Answer 11

Neuraxial anesthesia

• spinal anesthesia can exacerbate hypotension
• epidural - better option
  
  • carefully titrate to avoid hypotension
  • dosing is more controlled

Question 12

What anes meds trigger carcinoid crisis?

Answer 12

• Avoid triggering factors that provoke carcinoid crisis.
• AVOID meds that cause histamine release or stimulate autonomic nervous system

meds that trigger

• morphine
• mepridine (increase HR, histamine release)
• ketamine
• atracurium

Safe:

• antihistamines
• fentanyl, remifent
• prop, etomidate
• vec, roc, cis-at
• volatile agents

Question 13

what is the management of carcinoid syndrome intra-op?

Answer 13

1) Bronchospasm

• monitor airway pressure
• avoid hypoxia and hypercarbia
• octreotide tx as necessary

2) temp
* avoid hypothermia (trigger)
3) hypotension

• fluid resucictation
• octreotide tx as neccesary
• tell sx to stop manipulating tumor (may be the cause)
• vasopressor (phenylephrine, vasopressin)
  
  • epi, norepi, dopa (worsen hypotension by triggering vasoactive mediator release)

4) HTN

• octreotide tx
• deepen anesthesia
• opioids
• esmolol
  
  • NTG and SNP may trigger release

Question 14

what is the post-op management of carcinoid syndrome?

Answer 14

• ICU monitoring
  
  • some remaining functional undetected mets
    
    • ​need to continue to avoid triggers - hypoxia, hypercarbia, hypothermia
  • vasoactive mediators remain in circulation for a while –> still can cause s/sx of carcinoid syndrome –> need close monitoring
  • elevated serotonin levels delay emergence
• continue octreotide infusion
• Pain
  
  • opioids
  • Epidural
• PONV
  
  • zofran (serotonin antagonist)