Veterinary Anesthesia & Analgesia Support Group
Practical Information for the Compassionate Veterinary Practitioner
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    I Drugs
    Alphabetical Drug Summaries
    Dr. Bob Stein


a)      Classification

i)        Fluorinated hydrocarbon

b)      General Information

i)        Considered one of the safest common inhalant agent for patients and staff

ii)       Its low solubility provided for quick inductions, level adjustments, and recoveries

iii)     MAC

(1)   Dog - 1.2%

(2)   Cats - 1.5%

c)      Advantages/Recommended use

i)        2nd most rapid inductions and recoveries of common inhalants

ii)       Does not sensitize the heart to epinephrine induced arrhythmia

iii)     Along with sevoflurane, an inhalant anesthetic of choice for patients with:

(1)   Liver disease

(a)    Minimal hepatic metabolism

(2)   Intracranial disease

(a)    Less effect on CSF pressure when compared to Halothane

(b)   Maintain ETCO2 at 20 - 30 mm Hg to minimize increases in CSF pressure

d)      Cautionary Information   

i)        Commonly causes respiratory depression

ii)       At higher levels (esp. > 2 x MAC) can be potent cardiac depressant and vasodilator

iii)     Can cause some increased CSF pressure

e)      Dosage Information

i)        Routine use

(1)   Mask Induction (not recommended for routine use)

(a)    Start with 100% oxygen @ 3 liters/min for 3 - 5 minutes

(b)   Do not cover patients eyes

(c)    After 3 - 5 minutes of O2, start isoflurane @ 0.5 %

(d)   Increase by 0.5 % every 30 - 60 seconds until 2 % is reached

(e)    Then increase to 3.5 % - 5 % to complete induction

(2)   Induction following injectable agent

(a)    Initiate flow rates of 1.0 to 1.5 liter per minute at 3.0 % - 5.0 %

(i)      Reduce percentage as indicated by patients response

(3)   Maintenance – Moderately low flow use

(a)    Once stable, reduce oxygen flow to 500 ml to 1 liter

(i)      The reservoir bag must remain reasonably full

1.      If not, the flow rate must be increased and the machine must be examined for leaks at the earliest possible convenience

(b)   Remember that prior to surgical stimulation, a patient may appear adequately anesthetized only to show a dramatic response to stimulation

(i)      An experienced anesthetist should be able to anticipate and minimize this event

(ii)    Effective analgesic & sedative premeds will significantly reduce the level of inhalant agent necessary for maintenance of a surgical plane of anesthesia

f)       Cost

i)        Moderately low

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Last modified: February 16, 2011 .