Hypotension

Question 1

Define hypotension in the perioperative setting.

Answer 1

A decrease in blood pressure greater than 20% of the preoperative value.

Question 2

What are the clinical features of hypotension?

Answer 2

1. Reduced systolic, diastolic, or MAP
2. Orthostasis
3. Dizziness, syncope, LOC
4. Nausea
5. Pallor, cool moist skin
6. Tachypnea
7. Tachycardia

Question 3

What is the differential diagnosis of hypotension?

Answer 3

1. Decreased preload
2. Decreased afterload
3. Decreased contractility
4. Decreased HR

Question 4

What preload-related etiologies may cause intraoperative hypotension?

Answer 4

Hypovolemia
decreased venous return from surgical retraction or positioning
venous pooling from venodilation (e.g. neuraxial block)
pericardial tamponade
pulmonary embolism

Question 5

What afterload-related etiologies may cause intraoperative hypotension?

Answer 5

vasodilation from anesthetic agents, vasoactive drugs
sepsis
anaphylaxis
endocrine causes (adrenal insufficiency, myxedema coma)
sudden decrease in afterload (e.g. removal of aortic cross-clamp)

Question 6

What contractility-related etiologies may cause intraoperative hypotension?

Answer 6

myocardial ischemia/infarction
cardiomyopathy
negative inotropic drugs
valvular disease
dysrhythmias

Question 7

What is the management of hypotension?

Answer 7

1. Ensure ventilation
2. Verify hypotension
3. Be prepared to treat as cardiac arrest
4. Inform surgeon and ask about recent maneuvers
5. Turn off vaporizers and other vasodilating drugs
6. Improve position (temporarily place in trendelenburg or raise legs)
7. Expand circulating volume (crystalloid 10cc/kg)
8. Administer vasopressors
9. Review and treat probable causes
   Misc:
   A-line
   inotropes
   infusions
   TEE