BD Sympathomimetics are first line tx for asthma

Oxygen Therapy Flashcards by Alex Stein

Asthma results in

hyperresponsive rxn to allergen which can then lead to inflammation of airway and bronchospasm

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Chemical mediators with asthma

Histamine
ECF - A (eosinophilic chemo factor of anaphyl)
Prostaglandins
Leukotrienes

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Antihistamines used for asthma

usually only a small effect

Histamine is not a major factor

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ECF - A as a chemical mediator

released from eosinophils and mast cells and will attract more eosinophils

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Asthma is worsened by ___ stimulation

vagal stimulation

Inc PSNS brought on by anxiety/fear

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Vagus/parasympathetics will

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Sympathetics will

Sympathomimetics are first line tx for asthma

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Pediatric asthma

prevalence is inc

only sx can be cough

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pediatric asthma - mechanism

events early on (before 3 months) are stimulating the undifferentiated helper T cells which leads to an expression of pro-allergen cytokines which makes them more susceptible to asthma

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___ percent of asthma triggers are from ___

80% from airborne substances

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Quick relief to tx acute asthma attacks

short acting B2 agonists

they stimulate adrenergic receptors to cause VD

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Long term control to prevent acute asthma attacks

long acting B2 agonists 
corticosteroids
mast cell stabilizers
leukotriene modifers
methylxanthines

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Long term control to prevent acute asthma attacks - long acting B2 agonists - con to them

excessive reliance can lead to desensitization

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Long term control to prevent acute asthma attacks - corticosteroids are

first line agents fo rlong term control

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Long term control to prevent acute asthma attacks - leukotriene modifers - produced from

arachadonic acid

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Long term control to prevent acute asthma attacks - methylxanthines - mechanism

inhibit cAMP to maintain BD for a while longer

Prolong the sympathetic effect

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Long term control to prevent acute asthma attacks - Beta agonist are most effective in

relieving acute bronchospasm

relieve sx in 3-15 min

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Sole tx for mild episodic asthma and tx of choice for exercise induced asthma

B2 agonist

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asthma - B agonists - side effects

are transient
mm tremors
tachycardia
nervousness
agitation
hypertension
urinary retention
seizures

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B agonist for asthma - best to supplement with

other antiinflammatory

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B agonist for asthma - examples (3) and their mechanisms

levalbuterol - has only the active isomer of albuterol so it lowers side effects
formoterol and salmeterol - long acting for up to 12 hours - good for COPD or chronic sx of asthma

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Asthma - corticosteroids - mechanism

inhibit inflammatory response by inc number of B receptors and dec mucus production

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Asthma - corticosteroids - used for

long term suppression, control, reversal of inflammation

NOT for short term attack

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Asthma - corticosteroid - how long do you need to take it before see dec in airway inflammation

2 to 8 weeks

Corticosteroids - early asthma tx

If used aggressively early on, may limit progression of asthma

Side effects of corticosteroids - asthma

``` Thrush (fungal mouth infection) Dysphonia Appetite stimulation Inhibits growth up to 1cm per yr Osteoporosis HTN Immune suppression ```

Corticosteroids used for asthma - examples

Budesonide Fluticasone Combination for long term control could be advair and symbicort

ASthma - mast cell stabilizer - mechanism

Prevents release of histamine from mast cells which reduces the frequency and severity of the attacks Has mild antiinflammatory effects Used to reduce CS usage No BD activity

Asthma - mast cell stabilizer - side effects

``` transient bronchospasm cough/dry throat bitter taste nausea vomit ```

Asthma - mast cell stabilizer - how long do you have to take it before see max benefit

4-6 weeks

Asthma - mast cell stabilizer examples (2)

Cromolyn | Nedocromial

Asthma - Leukotriene modifier - mechanism

blocks LT synthesis or the receptor binding to decrease inflammation

Asthma - leukotriene used as

an alternative to reduce corticosteroid use

ASthma - long term acting ones are never used alone for the tx of asthma T or F

TRUE

Examples of leukotriene modifiers used for asthma

Singulair | Zileuton

Asthma - methylxanthines - mechanism

``` phosphodiesterase inhibitor Will dec Ca influx and elicit BD by inhibiting cAMP Dec histamine release Narrow therapeutic index Weak BD but is long lasting ```

COPD treatment - what is used

bronchodilators!!! - anticholinergics - B2 agonsits (long acting) - methylxanthines

COPD - only antinflammatory approved for COPD

advair

For pts who are hypoxemic at rest - only therapy documented to improve progression of COPD is what

supplemental oxygen

Hypoxemia is what

reduced oxygen in blood

Hypoxia is what

reduced oxygen in tissues

Oxygen tx - goals

eliminate hypoxia get SaO2 to 90 percent Ensures tissue oxygenation Reduces compensatory hypoxic responses

Oxygen tx - if inc in hypoxia can lead to

inc in sympathetic tone which causes inc hR, inc contractility, VC

Oxygen tx - if hypoxic in lungs can result in

pulmonary hypoxic VC | Vessels close down

Pros and cons to pulmonary hypoxic VC

we can push blood to areas of better gas exchange | inc resistance - harder on heart - inc afterload to R heart

Causes of hypoxemia

altitude (decrease PO2) hypoventilation (dec PAO2) Inadequate oxygenation of blood (dec PaO2) Impaired transport (poor tissue delivery) Inadequate of excessive O2 utilization - high metabolic demand

Effects of hypoxia

Vetilation - inc rate and depth Cardiovascular function - inc sympathetic activity Autoregulation of coronary and cerebral vasculature (VD) Pulmonary hypoxic VC

Big problem with hypoxia -

loss of ability to respond or loss of consciousness before the recognition of the problem

Effects of O2 on arterial blood gases

inc dissolved composition (PO2) High PaO2 impairs CO2 transport - and if CO2 accumulated can lead to acidosis Absorption atelectasis from nitrogen washout (from giving 100% oxygen)

Effects of 100% O2 on normal patient

``` 1 initial mild resp depression 2 CNS can have long term or concurrent stimulation or depression 3 dec sympathetic tone 4 VC of coronaries and cerebral vessels 5 no change in metabolism ```

Oxygen toxicity - as you lower the oxygen delivery amount a patient can

tolerate it for a longer period of time

100% oxygen at 1atm is safe for how long

24 hours

Effects of oxygen toxicity

1 absorptive atelectasis 2 resp depression 3 retrolental fibroplasia

Nature and severity of oxygen toxicity is determined by

degree of hyperoxygenation duration of exposure individual cell type

Guidelines for oxygen use

1 no problems with 100% O2 at 1 atm for 24 hrs 2 no sig problem if concentration of O2 is less than 50% at 1 atm 3 period breaks to dec toxicity 4 toxicity inc if pre existing pulm disease

Cause of toxicity is

PO2 NOT the concentration | Measure PaO2 and PaCO2 instead of just the saturation

Oxygen tx should be aimed at correcting

arterial hypoxemia

If tissue hypoxia occurs in absence of arterial hypoxemia, then tx should be directed at

underlying causes