Resp/Steroid Pharm Flashcards
1
Q
What is surfactant?
A
Naturally occurring substance produced by type II pneumocytes
2
Q
What is the primary function of surfactant in the alveoli?
A
Acts at air-liquid interface to reduce surface tension
3
Q
What does surfactant improve in the lungs?
A
Improved compliance
4
Q
What condition does surfactant prevent in the alveoli?
A
Prevents alveolar collapse/atelectasis
5
Q
When was surfactant approved by the FDA?
A
1990
6
Q
What is Laplace’s Law?
A
P=2T/r
7
Q
In Laplace’s Law, what does ‘P’ represent?
A
Pressure needed to resist collapse
8
Q
In Laplace’s Law, what does ‘T’ represent?
A
Surface tension
9
Q
In Laplace’s Law, what does ‘r’ represent?
A
Alveolar radius
10
Q
How does surfactant affect the pressure needed to prevent alveolar collapse?
A
Decreases pressure needed
11
Q
What type of cells form 97% of the lung lining?
A
Type I pneumocytes
12
Q
What is the main role of type II pneumocytes?
A
Produce and secrete surfactant
13
Q
What are lamellar bodies?
A
Contain surfactant material and fuse with plasma membrane to release surfactant
14
Q
When is surfactant recognized in lamellar bodies during gestation?
A
As early as the 24th week
15
Q
What percentage of surfactant is recycled?
A
Over 95%
16
Q
What is the half-life of surfactant turnover?
A
3 days
17
Q
What is the primary component of surfactant?
A
Phospholipids
18
Q
What percentage of surfactant is phosphatidylcholine?
A
70%
19
Q
What are the four types of surfactant proteins?
A
- A
- B
- C
- D
20
Q
Which surfactant protein is the most abundant?
A
Protein A
21
Q
What is a symptom of Protein A deficiency?
A
Increased susceptibility to infections
22
Q
What is the role of Protein B?
A
Critical for lung function
23
Q
What happens in case of Protein B deficiency?
A
Severe respiratory failure, early death
24
Q
What is the function of Protein C?
A
Enhances phospholipid absorption
25
What are symptoms of Protein C deficiency?
Minimal effects on survival or respiratory function
26
What is the function of Protein D?
Immune function and regulates surfactant balance
27
What are the primary factors increasing risk for surfactant deficiency?
* Prematurity
* Male
* Caucasian
* C-section without labor
* Perinatal asphyxia
* IDM
* Thyroid disease
* Chorioamnionitis
* Non-immune hydrops
28
What are common radiologic findings in surfactant deficiency?
* Hypoexpansion
* Reticular granular appearance
* Air bronchograms
29
What are the physiologic effects of surfactant administration?
* Increase lung gas volume
* Improve gas exchange
* Improve lung mechanics
* Decrease work of breathing
* Normalize alveolar size
30
What phase of lung development begins around 36 weeks?
Alveolar Phase
31
What is the significance of antenatal steroids?
Induce lung structural maturation
32
What are the effects of glucocorticoids on lung maturation?
* Increase surface area
* Increase lung volumes for gas exchange
* Increase number of Type II cells
33
What is the function of SP-A?
Maintains surfactant monolayer and innate host defenses
34
What is a key role of SP-D?
Pathogen recognition critical to innate defense
35
What happens in case of complete lack of SP-B?
Severe RDS, usually term, high mortality
36
What are the hormonal inducers of surfactant production?
* Corticosteroids
* Thyroid hormones
37
What is the consequence of insulin on surfactant synthesis?
Inhibits glycogen breakdown, impairing surfactant synthesis
38
What is the recommended timing for surfactant administration?
Early (within 2 hours)
## Footnote
Early surfactant administration is associated with decreased mortality and reduced risk of BPD.
39
What are the main effects of surfactant therapy?
Improvement of oxygenation
## Footnote
Surfactant therapy also reduces mortality before hospital discharge, death or BPD at 28 days.
40
What are the types of surfactants?
* Synthetic derived surfactant
* Animal derived surfactants
## Footnote
Animal derived surfactants include Surfactant TA, Survanta, Infasurf, and Curosurf.
41
What are the adverse effects of surfactant therapy?
* Transient hypoxia or bradycardia
* Airway obstruction
* Transient fall in BP or cerebral blood flow
* Pulmonary hemorrhage
* Air leak
## Footnote
These effects may require adjustments in ventilation post-surfactant administration.
42
What is the mechanism of action of caffeine in apnea of prematurity?
Adenosine receptor blockade
## Footnote
Caffeine blocks A1 and A2a receptors, leading to increased neural respiratory drive and improved respiratory muscle function.
43
What is the loading dose of caffeine for infants?
10-12.5 mg/kg
## Footnote
This is followed by a maintenance dose of 2.5-5 mg/kg q24h.
44
What are the side effects of caffeine therapy?
* CNS stimulation: irritability, restlessness
* CVS: tachycardia
* GI: intolerance
* Renal: increased urine flow rate
## Footnote
Caffeine can also lead to increased metabolic rate and oxygen consumption.
45
What distinguishes 'old' BPD from 'new' BPD?
'Old' BPD is related to damage from oxygen therapy and ventilation strategies, while 'new' BPD is seen in very premature infants with immature lungs.
## Footnote
The definition of BPD is often based on the infant's requirement for oxygen.
46
What are the indications for using bronchodilators like Salbutamol?
* Relief of severe bronchospasm
* Treatment of status asthmaticus
* Adjunctive treatment for hyperkalemia
## Footnote
Salbutamol acts as a beta-2 adrenergic agonist to relax bronchial smooth muscle.
47
What is the mechanism of action of inhaled steroids like Pulmicort?
Controls protein synthesis, depresses migration of leukocytes, reverses capillary permeability
## Footnote
Inhaled steroids are anti-inflammatory and anti-asthmatic.
48
What is the half-life of caffeine?
72-96 hours
## Footnote
This long half-life necessitates monitoring for several days after discontinuation.
49
What are the adverse effects of inhaled corticosteroids?
* Chest pain
* Fatigue
* Oral thrush
* Respiratory infections
## Footnote
These effects highlight the need for careful monitoring during treatment.
50
What is the recommended approach for treating BPD with corticosteroids?
Use of dexamethasone in the first week is not recommended
## Footnote
High-risk infants may benefit from low-dose hydrocortisone, but this carries risks for sepsis.
51
What is the significance of the Edmonton Antenatal Glucocorticoid Administration guidelines?
Guidelines on the use of glucocorticoids for fetal lung maturity
## Footnote
These guidelines help inform clinical practices regarding steroid administration in pregnant women at risk of preterm delivery.
52
Fill in the blank: The main effect of surfactant therapy is improvement of _______.
oxygenation
53
True or False: Synthetic surfactants have been found to be more effective than animal-derived surfactants.
False
## Footnote
Animal-derived surfactants have shown better effectiveness in clinical settings.
54
What is the recommendation regarding dexamethasone use in the first week for BPD?
Not recommended
## Footnote
CPS advises against the use of dexamethasone in the first week for treating BPD.
55
What may be considered for high-risk infants in relation to corticosteroids?
Low dose hydrocortisone
## Footnote
Be aware of increased risks for sepsis with this treatment.
56
Is routine use of inhaled corticosteroids for BPD prevention recommended?
Not recommended
## Footnote
CPS does not recommend routine inhaled corticosteroids for BPD prevention.
57
What is the mechanism of action of dexamethasone?
Anti-inflammatory; suppression of neutrophil migration, decreased production of inflammatory mediators, reversal of increased capillary permeability
## Footnote
Also suppresses normal immune response.
58
What is the onset of action for dexamethasone when given IV?
Rapid
## Footnote
Dexamethasone has a short duration when given IV.
59
What is the half-life of dexamethasone in ELBW infants?
9.26 +/- 3.34 hours
## Footnote
This indicates the duration of the drug's action in extremely low birth weight infants.
60
What can dexamethasone be used for in infants?
Airway edema
## Footnote
Typical dosage is 0.2 mg - 0.5 mg/kg, can be given q8h for up to 3 doses.
61
What trial studied low dose dexamethasone and what was the dosage?
DART trial; 0.15 mg/kg/day tapered over 10 days
## Footnote
The trial aimed to assess the effects on extubation and ventilation duration.
62
What is hydrocortisone's role compared to dexamethasone?
Less potent glucocorticoid; may mitigate adrenal insufficiency in premature infants
## Footnote
It has a greater risk of gastrointestinal perforation.
63
What are the three anatomic zones of the adrenal cortex?
* Zona glomerulosa: produces aldosterone
* Zona fasciculata: produces cortisol
* Zona reticularis: produces adrenal androgens
## Footnote
These zones are crucial for steroid hormone production.
64
What regulates glucocorticoid synthesis?
ACTH
## Footnote
Mineralocorticoid synthesis is regulated by the renin-angiotensin system and potassium ions.
65
What is the primary negative regulator of cortisol?
Cortisol itself
## Footnote
It exerts negative feedback on the anterior pituitary and hypothalamus.
66
What percentage of cortisol is bound to corticosteroid-binding globulin (CBG)?
>90%
## Footnote
This binding is important for the transport and regulation of cortisol.
67
What are the effects of glucocorticoids on growth?
Small increases in cortisol stimulate growth hormone secretion; chronic hypercortisolism suppresses growth
## Footnote
In small doses, glucocorticoids can enhance growth but can lead to suppression when chronically elevated.
68
What role do glucocorticoids play in fetal development?
Stimulate lung maturation by enhancing surfactant protein synthesis
## Footnote
This is crucial for reducing respiratory distress syndrome in premature infants.
69
How do glucocorticoids affect carbohydrate metabolism?
Increase blood glucose levels by acting on glycogen, protein, and lipid metabolism
## Footnote
They inhibit glucose uptake in peripheral tissues.
70
What impact do glucocorticoids have on the immune function?
Alter leukocyte traffic and function; decrease cytokine production
## Footnote
This increases the risk of infection.
71
What should be done when withdrawing glucocorticoids?
Should be weaned slowly
## Footnote
Especially in patients with repeated courses or adrenal suppression.
