Pharmacological differences:

The percentage of body water is greater in the premature infant. Preterms have 76% body water, term neonates 70% and an adult 60%. This will effect drug distribution. Volume of distribution is increased.

Adipose tissues are less; preterms have 1-5% bodyweight, term 10%, and adults 25-30%.

Absorption of drugs: The gastric pH is 5.0 at birth and decreases to adult values of 1-3 shortly thereafter. The gastric emptying rate is less than an adult value till 6-8 months.

Distribution: The free fraction of drug is increased because there is both: a decrease in total serum protein as well as serum albumin levels. Decrease amounts of alpha-l-glycoprotein affects binding of drugs. Protein-binding approximates adult values by 1 year of age.

The blood brain barrier is poorly developed so the entry of drugs such as narcotics is increased by 20-100%.

Metabolism: The half-life of many drugs is increased due to immaturity of liver enzymes.

ANESTHESIA:

Preoperative evaluation: The following points are peculiar to pediatric anesthesia:

History:
Physical examination:
Investigations

Generally, healthy ASA I patients for minor surgical procedures do not require any blood tests. Those coming for major procedures should have an Hb done. Other investigations should be done as appropriate for the case.

Rapport: It is very important to establish a rapport with both, patient and the parents. This will make life easier for everyone concerned later in the operating room.