Topics in Pediatric Physiology Flashcards
What is atelectasis?
complete or partial collapse of lung or section of lung
What is tachypnea?
abnormally rapid breathing
What is subglottic stenosis?
- narrowing of the airway below the vocal cords (subglottis) and above the trachea - involve narrowing of the cricoid - often caused by scarring in the larynx just below the vocal cords
What happens to the diaphragm when a patient is placed in supine position?
1) gastric organ pressure on the diaphragm
- recommended 20 to 30 degree head up position to prevent such pressure and minimize risk of regurgitation and aspiration
Compared to adults, children have ________ rate of of alveolar ventilation (AV) per unit area
increased, because they have a greater proportion of alveolar surface to lung size
proportionally greater exchange of gas across the alveoli
Total volume of gas exchanged in children is ____ than adults. Functional residual capacity is ______ in children than it is in adults
less, less
FRC: volume of gas remaining in the lungs at the end of a normal expiration
What ratio helps determine the rate at which changes in inspired gas concentration affect a clinical response?
AV/FRC
AV: Alveolar ventilation
FRC: Free residual capacity
AV supports transport of inhaled gas through the bloodstream and to the brain; FRC determines how much gas remains in the lungs during normal breathing
As ratio increases, body reacts more quickly to changes in inhaled gas concentrations
What is the average heart rate of a newborn?
120-170 beats per minute
What is the average blood pressure of a 6 year old boy?
110/70
What is the average blood pressure of a 3 year old female?
103/62
What is the average heart rate of a 3 year old?
80-120 beats per minute
What is the average heart rate of a 6 year old?
75-115
What is the formula for cardiac outpout (CO)?
CO=SV x HR
SV doesn’t change beacuse the infant heart is relatively inelastic and cannot make rapid changes in stroke volume
Sympthatic/Parasympathetic tone is more marked in immature nervous system. What does this mean?
Parasympathetic. more prone to significant bradycardias with vagal stimulation
What is often given to children undergoing manipulation of the airway such as intubation to prevent vagally induced bradycardia?
atropine - antimuscarinic/anticholinergic that inhibits parasympathetic system
treats slow heart rate and decreases saliva production during surgery
A decrease in cardio output causes ________ in the rate of inhaled anesthetic uptake
increase
40% of child’s cardiac output perfuses the brain
Infants and young children have _______________ acidity in their GI system
Decreased
adult levels not reached until 2 to 2.5 years of age. low acidity favors absorption of weakly acidic drugs like penicillins and cephalosporins, whereas the absorption of weakly basic drugs such as benzodiazepines is delayed
Infant GI system shows _____ gastric emptying times
increased
results in slower gastric drug absorption
Lower levels of which enzyme in the first 2 months of life are associated with sluggish oxidation of diazepam, phenytoin, and phenobarbital in neonate?
cytochrome p450 enzyme, children relatively deficient in liver enzymes responsible fo metabolizing, detoxifying, or altering a drug
What is deficient in neonates that makes drugs such as morphine, acetaminophen, steroids, and sulfa antibiotics unsafe?
glucuronyltransferase - conjugates drugs into excretable form
Deficiency in which enzyme in infant liver causes an exaggeration of the effects of succinylcholine?
pseudocholinesterase - infants could respond with prolonged apnea; deaths have been reported in associated with undiagnosed myopathies
What is glomerular filtration rate (GFR) and why is it important in newborns?
volume of fluid filtered by the kidney per unit of time; participates in excretion of drugs such as penicillins, short-acting barbiturates and phenobarbital; dosages of agents must be calculated to consider low infant GFR
What is tubular transport and why is it important in infants?
group of mechanisms that transfer drug and drug metabolites across renal tubular epithelium; morphine, atropine, sulfa antibiotics; decreased tubular transport rates in young infants and thus have narrower margins of toxicity
