Premedication
The many published reports on premedication have produced approximately
the same results: almost all sedatives are effective. The important issue is effectiveness
for individual anesthesiologists at their own institutions. The need for premedication
must be individualized according to the underlying medical conditions, the length
of surgery, the desired induction of anesthesia, and the psychological makeup of
the child and family. A premedication is not normally necessary for the usual 6-month-old
child but is warranted for a 10- to 12-month-old who is afraid to be separated from
parents. Oral midazolam is the most commonly administered premedication in the United
States.[244]
An oral dose of 0.25 to 0.33 mg/kg
(maximum, 20 mg)
generally results in very compliant children who will separate from their parents
without crying.[164]
A review of previous anesthetic
records is particularly helpful in ascertaining how the child has responded in the
past. The most difficult patients are those who have had many surgical procedures.
Premedications may be administered orally, intramuscularly, intravenously,
rectally, sublingually, or nasally. Although most of these routes are effective
and reliable, each has drawbacks.[238]
Oral or
sublingual premedications do not hurt but may have a slow onset or be spit out; drug
taste and patient cooperation are the main determinants of success. Intramuscular
medications hurt and may result in a sterile abscess. Intravenous medications may
be painful during injection or at the start of infusion. Rectal medications sometimes
make the patient feel uncomfortable, cause defecation, and occasionally burn. Nasal
medications can be irritating, although absorption is rapid. Midrange doses of intramuscular
ketamine (3 to 5 mg/kg) combined with atropine (0.02 mg/kg) and midazolam (0.05 mg/kg)
or oral ketamine (4 to 6 mg/kg) combined with atropine
(0.02 mg/kg) and midazolam (0.5 mg/kg; maximum, 20 mg) will result in a deeply sedated
patient.[238]
[245]
This intramuscular combination is generally reserved for patients who have failed
lighter premedication regimens in the past or those who refuse oral premedication.
Higher doses of intramuscular ketamine (up to 10 mg/kg) combined with atropine and
midazolam may be administered to patients with anticipated difficult venous access
to provide better conditions for insertion of the intravenous line. There is still
no ideal premedication or route of administration.
Anticholinergic drugs are not routinely administered intramuscularly
to children because they are painful on administration and do not significantly reduce
laryngeal reflexes during induction of anesthesia. On the other hand, atropine (0.02
mg/kg) administered orally or intramuscularly less than 45 minutes before induction
does reduce the incidence of hypotension during induction with potent inhaled anesthetics,
but only in infants younger than 6 months.[246]
