CHAPTER 6: FUNDAMENTAL PRINCIPLES OF PEDIATRIC PHYSIOLOGY & ANATOMY

3 consequences of child’s lung due to high ventilation

pneumothorax

air-trapping

lung collapse

readily absorbable

lipid / fat soluble drug

basic + basic / acidic + acidic → same composition

less absorbable

water soluble drug

acidic + basic → not the same composition

Neonates

a baby within 44 weeks of age from the date of conception

Infants

a child of up to 12 months of age

Child

1 to 12 years

Adolescent

13 to 16 years

pediatric tongue

One of the most obvious anatomical differences between an adult and child

is larger than the adult in relation to the amount of free space in the oropharynx

large tongue creates a significant probability for airway occlusion and leaves little room for airway swelling

The size of the tongue is thought to be one explanation for why children are obligate nose-breathers: breathing through the nose is easier because it provides a direct path for airflow without concern for any obstruction that the tongue may cause

infant larynx

resides superior to that of an adult (C4 to C5) and the epiglottis is proportionally larger

child’s chest wall

l is more elastic than that of an adult, requiring lower ventilation pressure to expand the lungs

child’s sternum

is less rigid, which means that ribs and intercostal muscles have less support.

respiratory physiology

The considerable differences in this between infants and adults explain why infants and young children have a higher susceptibility to more severe manifestations of respiratory diseases, and why respiratory failure is common problem in neonatal and pediatric intensive care units.

The appreciation of the peculiarities of pediatric respiratory physiology is not only essential for correct assessment of any ill child, but also for correct interpretation of any pulmonary function test performed in this population

hypoxia

The No. 1 cause of death in children

Lack of a patent airway or breathing adequacy → most common reason for its development

between 6 and 8 years of age

development of frontal and sphenoid sinus

present at birth

ethmoid and maxillary sinus

Heart rate of infants

is higher and decreases gradually over the first 5 years of life near to adult levels

immagure gastric mucosa

secretes low levels of acid

Low acidity of infants gut favors absorption of weakly acidic drugs:

• penicillins

• cephalosporins

whereas the absorption of weakly basic drugs:

• benzodiazepines

Mefenamic Acid

should not be given in patients 13 years old and below

due to its increased risk of stomach problems, such as bleeding or peptic ulcers

Liver function

is initially immature with decreased function of hepatic enzymes.

Barbiturates and opioids for example have a longer duration of action due to the slower metabolism

ASA I

A normal healthy patient and no risk during dental treatment

ex: Healthy, nonsmoking, no or minimal alcohol use

ASA II

A patient with mild to moderate systemic disease and minimal risk during dental treatment

ex: Mild to moderate systemic disease without substantive functional limitations or healthy with extreme anxiety and fear toward dentistry Example: Current smoker, social alcohol drinker, pregnancy, obesity, well-controlled Diabetes Mellitus and hypertension, mild lung disease

ASA III

A patient with moderate to severe systemic disease and increased risk during dental treatment

ex: Poorly controlled Diabetes of hypertension, Alcohol dependence or abuse, Implanted pacemaker

ASA IV

A patient with severe systemic disease that is a constant threat to life and significantly increased risk during dental treatment

ex: Recent (less than 3 months) Myocardial infarction

ASA V

A moribund patient who is not expected to survive without the operation

ex: Ruptured abdominal/thoracic aneurysm

ASA VI

Patient declared brain-dead whose organs are being harvested for donor purpose

2 ways in computing pediatric dosage

Clark’s rule → weight in pounds

Fried’s rule → age in months

Young’s rule → age in years

Cowling’s rule → age in next bday

Clark’s rule → weight in pounds

Young’s rule → age of the child in years

vital signs by age

practice question in sas