Veterinary Anesthesia & Analgesia Support Group
Practical Information for the Compassionate Veterinary Practitioner
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1)     GENERAL

a)      Induction and maintenance anesthetic plans should be reviewed by a staff veterinarian

b)      Regardless of the apparent similarity between anesthetic candidates, anesthetic agents should not be selected automatically.

i)                    Each patient should be considered a unique individual and the anesthetist must have considered the species, breed, size, age, attitude, health status, and planned procedure when selecting pre-anesthetic medications and anesthetic agents

c)      Insure that adequate monitors are present at the site of the procedure

d)      An anesthetic machine should be carefully examined and moved to the site of induction

i)                    insure adequate anesthetic is present in the vaporizer

ii)                  check for any system leaks

iii)                 confirm adequate oxygen source

iv)                select circuit hoses

(1)   the circuit hoses should always be significantly larger than endotracheal tube diameter to minimize system resistance

(2)   pediatric tubes for patients under 20 lbs.

(a)    Some prefer a nonrebreathing system for patients under 15 lbs.

(3)   Standard hoses for patients over 20 lbs.

v)                  Select a reservoir bag for circle systems

(1)   Bag size should be 3 to 5 times tidal volume

(a)    Tidal volume is 10 to 15 ml/kg

e)      A reasonable selection of endotracheal tubes should be available at induction. Make sure all disinfectant residue has been rinsed from the tubes prior to use. Chlorhexidine will cause significant mucosal irritation if allowed to contact the airways.

i)                    3 tube sizes usually will suffice – the size you expect to use, one size smaller, and one size larger

(1)   inflate the cuff prior to induction to insure no leaks are present

ii)                  Keep in mind that brachycephalic breeds have disproportionately smaller tracheal diameters than their body size would indicate

(1)   Select the size you expect to use and the next 2 smaller sizes

(2)   this is particularly true for large brachycephalic dogs such as English Bulldogs

f)        Confirm proper intubation by:

i)                    direct visual confirmation if possible

ii)                  palpation of one clearly defined, firm tube in the cervical region

iii)                 auscultation of lung sounds bilaterally when bagging patient

iv)                if the animal is draped, manually follow the tube to the laryngeal opening to confirm proper intubation

g)      1 - 2 drops of lidocaine (0.2 ml max.) can be placed on the arytenoids to facilitate cat intubation

h)      Because benzocaine(Cetacaineâ) is capable of producing deleterious methemoglobinemia, its use cannot be recommended. Lidocaine is the preferred topical laryngeal anesthetic as it is readily available and very inexpensive.

i)        Only inflate the endotracheal cuff to the point that a seal will allow bagging at 20 cm of water

i)                    excessive cuff pressure can cause serious tracheal damage including tracheal rupture

(1)   Simply feeling the small reservoir bubble at the cuff valve can be misleading

ii)                  to minimize risk of tracheal trauma, use a 3 cc syringe for cat and small dog cuff inflation and a 6 cc syringe for medium and larger dog cuff inflation

(1)   Inflate the cuff to low pressure, close the pop-off valve, and pressurize the system by squeezing the reservoir bag. Add or remove air from the cuff until you just hear gases leak around the cuff at 15 to 20 cm H2O circuit pressure

j)        An anticholinergic drug dose appropriate for the patient must be on hand at all times even if already given as a pre-anesthetic component

k)      A syringe containing saline should be available at all times during the procedure to flush the catheter after administering medications, facilitating the medication’s introduction into systemic circulation. It is common to use heparinized saline for this task but heparin may not be necessary if the catheter is connected to an active fluid line.

i)                    heparinized saline is produced by mixing 1 ml of heparin  (1000 units/ml) with 1 liter 0.9% Saline (or 0.5 ml of heparin in a 500 ml 0.9% saline bag)

(1)   A dated high visibility fluorescent orange label must be used to identify any medications added to a fluid bag

(2)   Discard heparinized saline bags over 1 week old

(a)    Immediately discard any fluid bags that contain cloudy fluid or those suspected to be contaminated

ii)                  Another option is to coat the inside of the syringe with heparin, empty the syringe of all excess heparin, then fill the syringe with 0.9% sterile saline.

(1)   This method reduces the wastage of the method above but may lead to some variability in heparin content and increase the potential for contamination of the heparin vial.

l)        The maintenance of a patient’s body temperature is an important consideration paramount to a successful outcome

i)                    The use of an insulating material during patient clipping/preparation should be considered to minimize body temperature loss that may occur from contact with a stainless steel surface.

(1)   This is especially critical for small, short haired animals

ii)                  During the anesthetic event, the patient should be maintained on a warm water blanket and covered with a towel when possible

(1)   Warm water blankets are relatively inefficient heat sources

(a)    Placing the patient directly on the pad is recommended

iii)                 Warm air patient warmers like the Bair Hugger are a particularly effective way to support patient body temperature

(1)   The surgical site should be fully draped before the Bair Hugger is turned on to minimize the contamination risks of the increased regional airflow

iv)                IV fluids can be warmed at the time of administration by:

(1)   curling up the terminal portion of the IV line and placing it under the warm water blanket

(2)   utilizing a commercial IV fluid warmer

v)                  Bubble wrap is an efficient insulating material

m)    Additional induction agent should be on hand at all times to accommodate:

i)                    Sudden patient arousal due to:

(1)   Surgical stimulation

(2)   Improper endotracheal tube placement or tube slippage during procedure

ii)                  Respiratory distress at extubation requiring patient re-intubation

    Induction Protocols
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Last modified: April 9, 2011 .