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TITLE:   INHALATION INDUCTION IN INFANTS - Keywords
SOURCE:  Dept. of ANESTHESIOLOGY, UTMB
DATE:    March 3, 1995 
RESIDENT PHYSICIAN:     
FACULTY: Shailendra Joshi, M.D.               
DATABASE ADMINISTRATOR: Melinda McCracken, M.S.
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                      INHALATION INDUCTION IN INFANTS


Inhalation induction is very common and useful in infants because
of difficulty getting IV access in an awake child.  However, IV
induction is preferred if venous cannula is already in place.

A combination of oxygen, nitrous oxide and halothane are used. 
Enflurane and isoflurane are avoided because of their ethereal
pungicity.  Halothane should be slowly added to prevent
bronchial irritation and possibly laryngospasm.

A constant monotonous voice can calm an upset child.

After induction, you can switch to isoflurane which has less
cardio vascular depressant effect than halothane.

In general inhalation induction is quicker in children because of
a lower FRC per body weight and a higher percent of vessel risk
groups (ie brain) per body weight.

Complications of inhalation induction include breath-holding,
laryngospasm, and stomach distention.  There is a higher
incidence of bradycardia, hypotension, and cardiac arrest during
inhalation induction in children compared to adults.

A single breath halothane technique is rarely necessary. The
breathing system is primed with 5% halothane and the face mask
tightly applied. A single vital capacity breath taken by the
patient would rapidly induce anesthesia. 

Be aware of cardiac shunts.
     Right to left shunt   slower uptake
     Left to right shunt   faster uptake

Once induction is completed, the infant can be intubated as usual
with succinylcholine.  Atropine should be used to prevent
succinylcholine induced bradycardia (infants have rate-dependent
cardiac output). Recent concerns about the use of succynlcholine have
led to the more frequent use of other competitive blocking drugs.

Inhalation induction is often necessary in patients with significant
airway obstruction, e.g. epiglottitis. Such induction is frequently
slow due to decreased alveolar ventilation, increased cardiac output,
avoidance of nitrous oxide and fever ( increases the MAC and cardiac
output ).

Anesthetic requirements vary with age.  Generally, the MAC is higher
in children than in adults. In infants the MAC is smaller than
children but quickly rises until age one.

REFERENCE:

     Clinical Anesthesia - Barash p. 1338.