Maintaining Anesthesia: TIVA & PIVA

Question 1

What part of anesthesia has the largest impact on the cardiorespiratory system? How can this be mitigated?

Answer 1

inhalants —> dose-dependent!

use adjuncts to reduce inhalant requirements by providing analgesia and optimizing cardiovascular and respiratory system function

Question 2

What is the difference between PIVA and TIVA?

Answer 2

PIVA = most common; use of combinations of inhalants, IV, and IM medications

TIVA = no inhalant agents used, usually done for critical or complex patient procedures or when inhalation agent delivery may be challenging (increased ICP due to brain tumor)

Question 3

What action do benzodiazepines have as a part of PIVA/TIVA?

Answer 3

anxiolytic and muscle relaxation

• midazolam
• typically not potent enough by themselves and used with an opioid

Question 4

What action do opioids have as a part of PIVA/TIVA?

Answer 4

analgesia and minimal cardiovascular effects

• fentanyl
• hydromorphone
• morphine

Question 5

What action do alpha-2 agonists have as a part of PIVA/TIVA?

Answer 5

sedation, analgesia, muscle relaxation, and cardiovascular depression

• dexmedetomidine
• medetomidine

Question 6

What action does ketamine have as a part of PIVA/TIVA? At low doses?

Answer 6

analgesia, anesthesia

cardiovascular effects minimized

(good in CRIs!)

Question 7

What action do anesthetic agents used in PIVA/TIVA lack? What do they still do?

Answer 7

analgesia

contribute to cardiovascular and respiratory depression

Question 8

What action do local anesthetics have as a part of PIVA/TIVA?

Answer 8

analgesia, anti-inflammatory, antiarrhythmic, prevent ileus

• lidocaine in dogs only

Question 9

Calculate the CRIs for 5 mcg/kg/hr of fentanyl (50 mcg/mL), 1 mg/kg/hr of ketamine (100 mg/mL), and 50 mcg/kg/min of 2% lidocaine for a 30 kg patient.

Answer 9

(5 mcg/kg/hr) x 30 kg = 150 mcg/hr
(150 mcg/hr) / (50 mcg/mL) = 3 mL/hr undiluted

(1 mg/kg/hr) x 30 kg = 30 mg/hr
dilute to 10 mg/mL (1 mL ketamine, 9 mL saline)
(30 mg/hr) / (10 mg/mL) = 3 mL/hr

(2% = 2g/100mL = 0.02g/mL = 20 mg/mL)
(50 mcg/kg/min) x 60 min/hr = 3000 mcg/kg/hr = 3 mg/kg/hr
(3 mg/kg/hr) x 30 kg = 90 mg/hr
(90 mg/hr) / 20 mg/mL = 4.5 mL/hr undiluted

Question 10

What is important to add when inhalants are being used?

Answer 10

• premedications
• local anesthesia/analgesia techniques
• adjunct analgesia to minimize inhalants (hypotension common and dose-related)

Question 11

What are the most common drugs used in CRIs?

Answer 11

ketamine and fentanyl

• use half the dose of premedication

Question 12

What drugs are commonly used in microdoses to get through the worst without increasing inhalant?

Answer 12

• ketamine 1 mg/kg
• dexmedetomidine 0.25 mcg/kg
• small dose of propofol or alfaxalone if patient gets too light