Longnecker's Anesthesiology > Part 2. Preparing for Anesthesia > Section B. Preoperative Evaluation of the Anesthesia Patient > Chapter 19. Evaluation of Children Randall C. Wetzel, MBBS, MRCP, LRCS, MBA, FAAP, FCCM

Key Points

"1. The percentage of total body composition that is water decreases with age; intracellular fluid increases, whereas extracellular fluid decreases.

2. Fat and muscle mass increase from 13 to 22% and 20 to 50%, respectively, with age.

3. The distribution of blood flow varies, with a decreased percentage of flow going to the vessel-rich groups with increased age.

4. Infants have a large tongue and relatively small jaw. Infants usually are described as having an anterior and cephalad displacement of the airway with the narrowest segment at the level of the cricoid. The epiglottis generally is large and floppy compared with that of adults.

5. Younger children tend to experience airway closure and alveolar collapse with atelectasis because the end-expiratory lung volume from which tidal breathing occurs is close to closing capacity.

6. Although the functional residual capacity in mL/kg is smaller in infants compared with adults (30 vs. 34), increased oxygen consumption is the major factor in the rapid desaturation of infants.

7. The perioperative risk of reversion to a transitional circulation is related to pulmonary hypertension triggered by hypoxemia, hypercarbia, hypothermia, acidosis, and increased catecholamines.

8. Cardiac output depends on heart rate in..."