Apnea Flashcards
Methylxanthines were first reported as effective in what decade?
1970’s
What 2 Methylxanthines are 1st line treatment for Neonatal Apnea?
Caffeine
Theophylline
What are the MOA’s of Methylxanthines?
- Respiratory Center Stimulation
- Improvement in Respiratory Muscle Contraction –the above 2 are the biggest-
- Altered Sleep States
- Metabolic Rate
- Cardiac Output
- Metabolic Homeostasis (increased oxygenation and glucose–>decreased Apnea)
- Potentiation of Catecholamine effect (increased oxygenation)
- May provide an anti-inflammatory action in the immature lung
How does Improvement respiratory muscle contraction work to decrease Apnea?
- Increased Respiratory Muscle Fxn
- Improved Diaphragmatic Efficiency
- Increased Force Production w/electrical stimulation
- Decreased recovery time of fatigued muscles (fatigue a/w Apnea)
- Increase in Neuromuscular transmission–>Increased muscle tone–>r/t increased FRC & better oxygenation
How does Respiratory center stimulation work to decrease Apnea?
- Increased minute ventilation
- Decreased PaCO2 by increasing CO2 sensitivity
- Increasing in most indices of neurorespiratory drive (Vt)
- Optimal ventilatory responses (doses 10 mg/kg)
- Antagonize depressive effects of Narcotics (Codeine, MsO4, Niperidine)
Even in Methylxanthine doses as low as 2.5 mg/kg, what will be noted in the NB?
Increased Vt
Pharmacokinetics =
The study of the action of drugs within the body.
what the body does with the drug
What does Pharmacokinetics include?
Absorption Distribution Metabolism Excretion Onset of Action Duration of Effect Biotransformation Effects of routes of excretion of drug metabolites
Plasma clearance and elimination are ________ in newborns
Prolonged
Why can Caffeine be given more sparingly?
Why is drug monitoring not so critical w/Caffeine vs. Theophylline?
Because Caffeine’s T2 is 100 hrs (vs. 30 hrs in Theophylline
~25% of Theophylline is methylated to Caffeine. The plasma level at steady state fluctuates.
What is the desired plasma level of Caffeine?
Theophylline?
5-20 mg/L
5-15 mg/L
What is the dosing interval for Theophylline?
1-3 times/day
What is the dosing interval for Caffeine?
1 time/day
What is the preferred alternative in infants with Apnea of prematurity?
Why?
Caffeine
- Longer T2
- Wider therapeutic range (w/lower toxicity risk)
- Decreased rate adverse effects
- Ease of change from IV to PO (equivalent bioavailability
Both Caffeine and Theophylline can lead to what side effect?
Increased urinary excretion of Ca++