Page 37 - CASA Bulletin of Anesthiology 2021, Vol 8, No. 6 (1)

Vol. 8, No. 6, 2021

Ketamine and Its Use as an Infusion for Lasting Effects in the

Outpatient Treatment of Chronic Pain: A Narrative Review Article

Erin M McElhone, DO
PGY4 Anesthesia resident
Walter Reed National Military Medical Center
National Capital Consortium

Andrew Mannes, MD, Chief
DPM, CC, NIH

Background
The dissociative anesthetic, Ketamine, is one of the few
anesthetics that alone can provide all the components of a general
anesthetic: analgesia, amnesia, anxiolysis, anesthesia (awareness),
and muscle relaxation. In addition, it is able to maintain airway
reflexes. These unique properties lend to its many uses, such as a
general anesthetic, induction agent, procedural sedative, infusion
for acute pain, chronic pain, and depression. This article will
overview Ketamine and then delve into evidence for its lasting
effects when used as an infusion to treat chronic pain.

Side Effects

Cardiopulmonary
Ketamine can increase blood pressure, heart rate, cardiac output, and myocardial oxygen
demand by causing a systemic release of catecholamine, vagal nerve inhibition, and
norepinephrine reuptake inhibition. For this, the use of ketamine may want to be avoided in a
1
variety of situations. It can cause ischemia in high-risk patients, such as those with coronary
artery disease. In surgeries where increases in blood pressure can be detrimental, such as
aneurysm clipping, ketamine may be avoided. On the other hand, Ketamine's catecholamine
release can have positive influences in patients with bronchospasm by causing bronchodilation.
It can also be helpful on induction in patients that need blood pressure maintained, however
ketamine is a direct myocardial depressant. This cardiac depression is generally negated by the
catecholamine release, but with catecholamine depletion, such as that seen with prolonged shock,
cardiac collapse could still result.
Psychiatric

Bolus dosing and infusions have been associated with psychomimetic effects, such as
hallucinations, delirium, out of body sensation. Thus, consider avoiding the use of ketamine in
patients with delirium, PTSD, or prior negative experiences. It is patient dependent whether
psychomimetic effects are taken negatively or positively, and there does not seem to be a dose
response relationship on how patients perceive these effects as positive, negative, or tolerable.
2, 3

P a g e 36 | 69