Asthma
See also
Status
Asthmaticus |
Bronchitis |
COPD
REF: ACP Medicine Best Dx/Best Rx 2006
|
Definition/Key Clinical
Features | Differential Diagnosis
| Best Tests | Best Therapy |
Best References |
Drugs for Asthma/COPD |
Definition/Key
Clinical Features
-
Reversible narrowing of airways in response
to various stimuli and airway inflammation
-
During periods of normal lung function,
no abnormal physical findings
-
Symptoms: always try to quantifye.g.,
mild-moderate-severe, scale 15
-
Wheezing
-
Cough (nonproductive or with copious
sputum)
-
Shortness of breath
-
Chest tightness (often confused with
angina pectoris)
-
Desperate hunger for air with severe
attacks
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Classification of asthma severity
and step-wise therapy
For All Patients - Quick Relief Rx:
-
Short-acting bronchodilator: 2-4 puffs short-acting inhaled beta2-agonists
as needed for Sx.
-
Intensity of Rx will depend on severity of exacerbation; up
to 3 Rx at 20-minutes intervals or a single nebulizer Rx as needed. Course
of systemic corticosteroids may be needed.
-
Use of short-acting beta2-agoniss > 2 x/week in intermittent asthma
(daily, or increasing use in peersistent asthma) mah indicate the need
to initiate (increase) long-term therapy.
-
Mild intermittent
Treat patients with mild intermittent asthma with a quick relief
medication (e.g., a short-acting
ß-agonist).
- Symptoms <=2 per week, Asymptomatic and normal PEF between exacerbations,
Exacerbations brief (a few hours to a few days); intensity may vary: nocturnal
Sx <=2 per month;
- FEV1 or PEF >=80% predicted; PEF variability
<20%
Long-term control: No daily medication needed
-
Mild persistent
Treat patients with mild persistent asthma with one long-term controller
medication.
- Symptoms >2 per week but <1 per day; Exacerbations may affect activity;
Nocturnal Sx >2 per month
- FEV1 or PEF >=80% predicted; PEF variability 20%-30%;
Long-term control: One daily medication:
Anti-inflammatory*: either inhaled corticosteroid
(low doses) or cromolyn* or nedocromil* (children usually begin
with a trial of cromolyn or nedocromil); Sustained-release theophylline to
serum concentration of 5-15 µg/mL is an alternative, but not preferred,
therapy. Montelukast, zafirlukast, or zileuton may also be considered for
patients age 12 and older, although their position in therapy is not fully
established
-
Moderate persistent
Treat patients with moderate persistent asthma with one or two long-term
controller medications.
- Daily symptoms;Daily use of inhaled short-acting Beta2-agonist; Exacerbations
may affect activity; Exacerbations >=2 per week; may last days; Nocturnal
Sx >1 per week
- FEV1 or PEF >60%-<80% predicted; PEF variability
>30%
Long-term control:
Preferred treatment: Low-to-medium dose inhaled corticosteroids and
long-acting inhaled Beta2-agonists.
Alternative treatment: Increase inhaled corticosteroids within medium-dose
range, OR Low-to-medium dose inhaled corticosteroids and either leukotriene
modifier or theophylline.
If needed (particularly in patients with recurring severe exacerbations):
Preferred treatment: - Increase inhaled corticosteroids within medium-dose
range, and add long-acting inhaled Beta2-agonists.
Alternative treatment: Increase inhaled corticosteroids in medium-dose
range, and add either leukotriene modifier or theophylline
-
Severe persistent
Recognize that patients with severe persistent
asthma may require at least three
daily medications to manage their disease.
- Continual symptoms; Limited physical activity; Frequent exacerbations;
Nocturnal Sx frequent;
- FEV1 or PEF <60% predicted; PEF variability >30
%
Long-term control:
Preferred treatment: High-dose inhaled corticosteroids AND Long-acting
inhaled ?2-agonists AND, if needed, Corticosteroid tablets or syrup long
term (2 mg/kg·d, generally do not exceed 60 mg/d). (Make repeat attempts
to reduce systemic corticosteroids and maintain control with high-dose inhaled
corticosteroids.)
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Differential Diagnosis
-
Upper airway obstruction
-
Viral tracheobronchitis
-
Chronic obstructive pulmonary disease
-
Congestive heart failure
-
Pulmonary embolism
-
Churg-Strauss syndrome
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Definition/Key Clinical
Features | Differential Diagnosis
| Best Tests | Best Therapy |
Best References |
Drugs for Asthma/COPD |
Best Tests
No single lab test can establish diagnosis; bronchodilator responsiveness
provides supportive evidence
-
Spirometry
-
> 15% increase in airflow (FEV1 or FVC) after bronchodilator
inhalation suggests asthma
-
Lacks sensitivity and specificity
-
False negatives occur during asymptomatic periods
-
False positives occur with chronic bronchitis, emphysema, or other diseases
with chronic airflow obstruction
-
Bronchoprovocation with methacholine
-
May be helpful if pulmonary function is normal
-
Abnormal response is > 20% decline in FEV1
-
Other provocative agents are cold, exercise, and histamines
-
CXR may exclude alternative diagnoses; not recommended for screening
or diagnosis
-
CBC, sputum exam, IgE measurement, allergy skin test not useful in
most cases
Red Flags
-
Following factors suggest greater risk:
-
Advanced age
-
Greater airway reactivity
-
Previous use of mechanical ventilation
-
Long-term steroid therapy
-
Previous hospitalizations for asthma
-
Problems with compliance
-
Major psychiatric diagnoses
-
Use of major tranquilizers
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Definition/Key Clinical
Features | Differential Diagnosis
| Best Tests | Best Therapy |
Best References |
Drugs for Asthma/COPD |
Determine the Need for
Hospitalization
Assess peak flow and patient respiratory symptoms
to determine need for hospitalization.
* Hospitalize patients with:
-
An incomplete response to therapy during an exacerbation (PEFR >=50%,
but <70% of predicted)
-
Mild-to-moderate symptoms
* Admit to intensive care unit any patients with:
-
A worse response to therapy (FEV1 or PEFR <50% of predicted)
-
An elevated partial pressure of carbon dioxide (PaCO2)
-
Severe symptoms
Recognize that certain historical factors reflect
risk for near-fatal and fatal events and lower the threshold for hospital
admission for a person with an acute exacerbation.
Lower the threshold for admission for patients having:
o An asthma exacerbation with a history of:
-
Prior intubation
-
Multiple asthma-related hospitalizations
-
Emergency department visits during the previous 12 months
-
Low adherence to inhaled corticosteroids
o Acute asthma exacerbations with a history of:
-
Depression
-
Substance abuse
-
Personality disorders
-
Unemployment
-
Recent bereavement
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Definition/Key Clinical
Features | Differential Diagnosis
| Best Tests | Best Therapy |
Best References |
Drugs for Asthma/COPD |
Best
Therapy
Emergency
-
Assess oxygenation by pulse oximetry
-
Increase O2 sat to
>90%
-
Measure ABGs
-
Rapidly evaluate for hypercapnia,
pneumothorax, atelectasis, or pneumonia
-
Administer shorter-acting beta-adrenergic agonist by inhalation
1. Remove underlying precipitating causes, as infection, chemical irritation,
anxiety, etc.
2. O2 supplement, hydration, antibiotics, & sedatives cautiously
3. Bronchodilators
4. Anti-inflammatory Meds
5. Bronchoscopic removal of mucus plugs, etc.
6. Mechanical ventilator
7. Misc: Magnesium 1.2 g in 150ml NS IV over 20 min after albuterol nebulizer
Rx.
8. Lung Volume Reduction Surgery (LVRS) in selected patients with
symptomatic upper lobe emphysema.
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Definition/Key Clinical
Features | Differential Diagnosis
| Best Tests | Best Therapy |
Best References |
Drugs for Asthma/COPD |
Best
References
-
Busse W, Raphael
GD, Galant S, et al: Low-dose fluticasone propionate compared with montelukast
for first-line treatment of persistent asthma: a randomized clinical trial.
J Allergy Clin Immunol 107:461, 2001
-
Busse WW, Lemanske RF Jr: Asthma. N Engl J Med 344:350, 2001
-
Busse, et al: J
Allergy Clin Immunol 107:461, 2001
-
Busse, et al: N Engl J Med 344:350, 2001
-
Cochrane, et al:
Chest 117:542, 2000
-
NIH Guidelines (NIH Publication No 97-4051), Bethesda, Maryland,
1997 (www.nhlbi.nih.gov/health/prof/lung/asthma/practgde.htm)
-
Shrewsbury, et al: BMJ 320:1368, 2000
-
Suissa, et al:
J Allergy Clin Immunol 107:937, 2001
-
Taylor, et al:
Thorax 55:595, 2000
-
Virchow, et al:
Am J Respir Crit Care Med 162:578, 2000
July 2004 |
Definition/Key Clinical
Features | Differential Diagnosis
| Best Tests | Best Therapy |
Best References |
Drugs for Asthma/COPD |
Treatment of
Status Asthmaticus in Children
Definition of
Status
Asthmaticus:
A sudden intense and continuous aggravation of a state of asthma, marked
by dyspnea to the point of exhaustion and collapse and not responding to
the usual therapeutic efforts.
REF: E-Medicine January 17, 2006 Adam Schwarz, MD,
http://www.emedicine.com/ped/topic2150.htm
Overall care for a child with asthma includes intensive outpatient treatment
with medications and alteration of the environment.
Admission to the hospital represents a failure of outpatient management.
This discussion is limited to inpatient treatment for status asthmaticus.
* Oxygen
-
Oxygen is the primary therapeutic modality.
Supplemental oxygen must be provided in any patient who presents with status
asthmaticus. Oxygen helps to correct V/Q mismatch. Oxygen can be provided
via nasal cannula or face masks.
-
In the event of significant hypoxemia, nonrebreathing masks may be used to
deliver as much as 98% oxygen. The goal in supplemental oxygen therapy is
to maintain oxygen saturation above 90%.
* Inhaled beta-agonists
-
Beta-agonist agents, typically albuterol or salbutamol,
and terbutaline, are the mainstays of acute therapy in asthma.
They act via stimulation of cyclic adenosine monophosphate (AMP)mediated
bronchodilation. The airway is rich in beta-receptors; the stimulation of
these receptors relaxes airway smooth muscles, increases mucociliary clearance,
and decreases mucous production.
-
The nebulized inhaled route of administration is generally the most effective
route of delivery, though some patients with severe refractory status asthmaticus
may benefit by the addition of beta-agonists delivered intravenously.
Beta-agonists are generally most effective in the early asthma reaction phase.
However, patients who present with status asthmaticus despite frequent use
of beta-agonists at home may have tachyphylaxis and resistance to these agents.
Therefore, these patients may not respond as well when these agents are given
in the hospital. Inhaled beta-agonists can be administered intermittently
or as continuous nebulized aerosol in a monitored setting.
* Corticosteroids
-
Corticosteroids, such as methylprednisolone or
prednisone, are critical in the therapy of status asthmaticus
and are used to decrease the intense airway inflammation and swelling in
asthma. In addition, corticosteroids potentiate the effects of beta-agonist
agents and improve capillary leak. Therefore, corticosteroids affect the
late asthma reaction phase.
-
Corticosteroids may be administered intravenously or orally. Although
most practitioners administer corticosteroids intravenously during status
asthmaticus, some studies indicate that early administration of oral
corticosteroids may be just as effective.
* Anticholinergics
-
Anticholinergic agents act via inhibition of cyclic guanosine monophosphate
(GMP)mediated bronchoconstriction. They may also decrease mucus production
and improve mucociliary clearance
-
Ipratropium bromide (Atrovent), a quaternary
amine that does not cross the blood-brain barrier, is the recommended
sympathomimetic agent of choice. Atropine, a tertiary amine, may also be
used and nebulized but may cause CNS effects because it may enter the CNS.
In patients with severe airflow obstruction, the combination of ipratropium
and albuterol can provide better bronchodilatation than albuterol alone.
* Further therapy: Although not as well investigated in large-scale, randomized,
controlled trials, other therapies may be helpful when the standard combination
of oxygen and intermittent or continuous beta-agonists (ie, albuterol),
intermittent inhaled anticholinergics (ie, ipratropium bromide), and
corticosteroids are insufficient in relieving significant respiratory distress
in severe acute asthma. These include the following:
o Magnesium sulfate
-
Magnesium can relax smooth muscle and
hence cause bronchodilation by competing with calcium at calcium-mediated
smooth muscle binding sites. The published doses used range from 25-75
mg/kg infused over 20 minutes, with a maximum of 2-2.5 g/dose. One
double-blind placebo-controlled study reported a significant increase in
peak expiratory flow, FEV1, and forced vital capacity in children who had
asthma and were treated with a single 40-mg/kg dose of magnesium sulfate
(MgSO4) infused over 20 minutes, along with steroids and inhaled bronchodilators,
compared with control subjects who received saline placebo. In addition,
patients who received intravenous magnesium were significantly more likely
to be discharged home from the presenting ED than control subjects (8/18
vs 0/14; P = .002).
-
No data currently exist regarding duration of effect or efficacy with repeated
doses, and no guidelines describe the monitoring of serum magnesium levels
if more than an initial magnesium dose is administered. In one small study
of 4 children who received 40-50 mg/kg MgSO4, serum magnesium levels were
all less than 4 mg/dL, whereas ECG changes are generally not seen until levels
exceed greater than 4-7 mg/dL. Adverse effects may include facial warmth,
flushing, tingling, nausea, and hypotension.
o Intravenous beta-agonists
-
Some patients with refractory status asthmaticus may respond to intravenous
administration of beta-agonists. Intravenous albuterol
and salbutamol may be administered where available but are not
available in the United States. Intravenous terbutaline
is most commonly used in the United States. Reported doses
for intravenous terbutaline have ranged from 0.4-10 mcg/kg/min in
children. Historically, isoproterenol has been used, but its potent beta1
stimulation may lead to significant tachycardia and inotropy, which has caused
myocardial infarction in adults.
-
The dose administered should be titrated to effect and adverse cardiac effects
(tachycardia, arrhythmias, ECG changes). Some practitioners advocate monitoring
cardiac enzyme levels in patients who receive prolonged significant infusions
of intravenous beta-agonists.
o Ketamine
-
Ketamine is a short-acting pentachlorophenol (PCP) derivative that exerts
bronchodilatory effects because it leads to an increase in endogenous
catecholamine levels, which may bind to beta-receptors and cause smooth muscle
relaxation and bronchodilation.
-
Case reports have also described the use of ketamine as a sedative to reduce
anxiety and agitation that can exacerbate tachypnea and work of breathing
and potentially obviate further respiratory failure in small children with
status asthmaticus.
o Methylxanthines
-
The role of methylxanthines, such as theophylline
or aminophylline, in the treatment of severe acute asthma has
been seriously challenged since the advent of potent selective beta-agonists
and their use at higher doses. At therapeutic doses, methylxanthines are
weaker bronchodilators than beta-agonists and have many undesirable adverse
effects, such as frequent induction of nausea and vomiting. Furthermore,
most studies have failed to show additional benefit when methylxanthines
are administered to patients who are already receiving frequent beta-agonists
and steroids.
-
Nevertheless, several recent prospective, randomized, controlled studies
in children with refractory status asthmaticus have reexamined the role
of the methylxanthines theophylline and aminophylline and demonstrated
improvement in the clinical asthma scores when compared with placebo
control. One study compared intravenous theophylline with intravenous
terbutaline in critically ill children with refractory asthma and demonstrated
equal therapeutic efficacy but significantly lower costs associated with
theophylline use. Among the theophylline effects that are important in managing
asthma are bronchodilatation, increased diaphragmatic function, and central
stimulation of breathing.
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Definition/Key Clinical
Features | Differential Diagnosis
| Best Tests | Best Therapy |
Best References |
Drugs for Asthma/COPD |
|
Medications for Asthma & COPD
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Beta-2 Agonist
* * Aerochamber - better delivery. Spacer device
Inhaled short-acting beta2
agonists:
first-line p.r.n. therapy;
no significant differences in efficacy among inhaled short-acting
beta2 agonists; dilute aerosols to minimum of 4 ml at gas
flow of 6-8 L/min
-
Albuterol (Ventolin, Proventil)
-
Nebulizer, 5 mg/ml 0.5 ml in 2.5 ml NS(2.5
mg)
-
Dose: maintenance, 1.255.0 mg
q. 48 hr p.r.n; exacerbation, 5 mg q. 2 hr
-
MDI, 84 ¼g/puff:
MDI as effective as nebulizer when
used with spacer
-
Dose:
maintenance,
24 puffs q. 6 hr p.r.n; exacerbation, 38 puffs q. 2
hr
-
Pirbuterol (Maxair)
-
MDI, 200 ¼g/puff
-
Dose: maintenance, 24 puffs q. 6 hr p.r.n.;
exacerbation, not studied
-
Alupent 0.3 ml in 2.5 ml
NS (15 mg) (Metaproterenol)
Combined short-acting beta2 agonist
and anticholinergic:
use when both are indicated
-
MDI
Combivent albuterol (90 ¼g/puff)
+ ipratropium bromide (18 ¼g/puff)
Dose: maintenance, not recommended;
exacerbation, 38 puffs q. 2 hr
Inhaled long-acting beta2 agonists:
first-line scheduled bronchodilator
therapy
-
Salmeterol
(Serevent Diskus): Slower onset of action;
not used as a rescue bronchodilator
-
MDI, 21 ¼g/puff
-
Dose: maintenance, 2 puffs q. 12 hr;
exacerbation, not recommended
-
Cost/mo: $50.0069.99
-
DPI, 50 ¼g/blister
-
Dose: maintenance, 1 blister q. 12 hr
-
Arformoterol tartrate
(Brovana) inhalation solution 15 mcg/2mL twice daily dosing by jet nebulizer.
-
Rapid onset: Median time to onset was 6.7-20
min after first dose; however it is not indicated for the Rx of acute
episodes of bronchospasm; it provided sustained bronchodilation over
the 12-hour dosing interval; it decreased the use of rescue albuterol and
supplemental ipratroium.
-
Dose: twice daily dosing
by jet nebulizer
-
Formoterol
(Foradil)
: faster onset of action than
salmeterol; may be used as a rescue bronchodilator
-
DPI, 12 ¼g/capsule
-
Dose: maintenance, 1 capsule q. 12 hr; exacerbation,
not recommended
Combined long-acting beta2 agonit and
corticosteroid:
-
Advair (fluticasone/Flovent +
salmeterol/Serevent) DPI 100/50, 250/50, 500/50) 1 puff bid
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Anticholinergic
drugs:
Atrovent (Ipratropium) inhaler 2-4 puffs
q6h
Atrovent 0.5mg (1 unit dose) nebulizer soln
in 2.5 mL NS 3-4x/d
Atropin 0.5 mg in 2.5 ml NS q6-8h
Spiriva HandiHaler (Tiotropium) 1 capsule
once daily
|
Inhaled Corticosteroids:
first choice of anti-inflammatory agents; various
inhaled corticosteroid agents differ in potency
-
Fluticasone (Flovent): highest
potency; also formulated in combination with salmeterol in DPI
-
Dose: low, 83-264 µg; medium, 264-660 µg;
high, > 660 µg
-
44 µg/puff: low, 2-4 puffs/day
-
110 µg/puff: low, 2 puffs/day; medium, 2-6
puffs/day; high, > 6 puffs/day
-
220 µg/puff: medium, 1-2 puffs/day; high,
> 3 puffs/day
-
Budesonide (Pulmocort): second-highest
potency; DPI inhaler
-
Dose: low, 200-400 µg; medium, 400-600 µg;
high, > 600 µg
-
220 µg/puff: low, 1-2 puffs/day; medium,
2-3 puffs/day; high, > 3 puffs/day
-
Beclomethasone
(QVAR): third-highest
potency; available in HFA MDI, possibly improving effectiveness
-
Dose: low, 168-504 µg; medium, 504-840 µg;
high, > 840 µg
-
42 µg/puff: low, 4-12 puffs/day; medium,
12-20 puffs/day; high, > 20 puffs/day
-
40-80 mcg 1-2 puffs bid
-
Flunisolide (Aerobid): lowest potency
-
Dose: low, 500-1,000 µg; medium, 1,000-2,000
µg; high, > 2000 µg
-
42 µg/puff: low, 4-12 puffs/day; medium,
12-20 puffs/day; high, > 20 puffs/day
-
Triamcinolone (Azmacort): lowest potency;
provided with spacer
Dose: low, 400-1,000 µg; medium, 1,000-2,000
µg; high, > 2,000 µg
100 µg/puff: low, 4-10 puffs/day; medium,
10-20 puffs/day; high, > 20 puffs/day
-
Asmanex (Mometasone) Twisthaler 220 mcg 1-2 inhalations daily PM
Systemic Corticosteroids
-
Prednisone: usual oral agent; q.d. initially, then wean off, if possible,
or switch to q.o.d.
-
Dose: initial, 0.5-1.0 mg/kg/day; maintenance, none or minimal
-
Methylprednisolone, oral: less
commonly used oral agent; q.d. initially, then wean off, if possible,
or switch to q.o.d.
-
Dose: initial, 24-48 mg/day; maintenance, none or minimal
-
Methylprednisolone, I.V.:
usual I.V. agent; oral therapy is as effective
-
Dose: initial, 60-125 mg IV q. 6-8 hr;
maintenance, none
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Leukotriene
Inhibitors:
less effective than inhaled corticosteroids; help with associated allergic
rhinitis; use for aspirin-sensitive patients
-
Montelukast
(Singulair): first choice of
leukotriene inhibitors; note q.h.s. dosing; no lab monitoring or restrictions
related to meals
-
Dose: 10 mg q.h.s.
-
Cost/mo: $60.00-69.99
-
Zafirlukast (Accolate): should
be taken at least 1 hr before or 2 hr after meals
-
Dose: 20 mg b.i.d.
-
Cost/mo: $50.00-59.00
-
Zileuton (Zyflo): must monitor
LFTs
-
Dose: 600 mg q.i.d.
-
Cost/mo: $79.00-89.99
-
Methotrexate (Rheumatrex, Trxall): efficacy
controversial; toxic drug, must monitor blood counts and LFTs closely; should
be given only by asthma expert
-
Dose: 7.5 mg/wk (adjust to effect; maximum 25
mg/wk)
-
Cost/mo:
$10.00-19.99
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OTHERS RX:
Cromolyn Sodium
(Intal): much less potent than
inhaled steroids; used more often in children; no steroid side
effects
-
Dose: initial, 2-4 puffs q.i.d.; maintenance,
2 puffs q.i.d.
-
Cost/mo:
$30.00-39.99/canister
Nedocromil:
much less potent than inhaled steroids; no steroid side
effects
-
Dose: initial,
2 puffs
q.i.d.; maintenance,
2 puffs q.i.d.
Nonselective beta-2 agonists
-
* Patients whose bronchoconstriction is resistant to continuous handheld
nebulizer treatments with traditional beta-2 agonists may be candidates for
nonselective beta-2 agonists (eg, epinephrine 0.3-0.5
mg SC q 30 min x 3; or
terbutaline 0.25 mg SC) administered
subcutaneously. However, systemic therapy has no proven advantage over aerosol
therapy with selective beta-2 agents.
Susphrine 0.1-0.3 ml 1:200 SQ
*Avoid or use cautiously in heart or HBP pts.
* Aminophylline
The loading dose is usually 5-6 mg/kg, followed
by a continuous infusion of 0.5-0.9 mg/kg/h
-
o Conflicting reports on the efficacy of aminophylline therapy have made
it controversial.
-
o Starting intravenous aminophylline may be reasonable in patients who do
not respond to medical treatment with bronchodilators, oxygen, corticosteroids,
and intravenous fluids within 24 hours.
-
o Recent data suggest that aminophylline may have an anti-inflammatory effect
in addition to its bronchodilator properties.
-
o The loading dose is usually 5-6 mg/kg, followed by a continuous infusion
of 0.5-0.9 mg/kg/h.
-
o Physicians must monitor a patient's theophylline level. Traditionally,
the level was targeted to the higher end of the local therapeutic range;
however, many authorities suggest that the lower portion of the range (ie,
>5 but <10) may be preferable if the patient can obtain the benefits
of the drug in the lower range.
-
o Adverse effects can include tachyarrhythmia, nausea, seizures, and anxiety.
Theophylline: third choice; relatively
weak bronchodilator; used only when all other agents optimized;
significant toxicity; must monitor levels
-
Dose: maintenance, 100200 mg b.i.d.;
exacerbation, adjust to serum level 1020 µg/ml
Proventil (Albuterol) 2-4mg tablet qid PO
REF: http://www.emedicine.com/MED/topic2169.htm 2004
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|
* [DPIdry-powder
inhaler; MDI--metered-dose inhaler] |
On the basis of careful serial studies of sputum specimens from patients
with chronic obstructive pulmonary disease, obtained during both stable periods
and exacerbations, the authors found that the appearance
of Streptococcus pneumoniae
or
Moraxella
catarrhalis in sputum cultures was
significantly associated with symptoms of exacerbation.
Furthermore, they subjected the sputum isolates to molecular typing
in order to identify different bacterial
strains. Exacerbations were more strongly associated with
changes in the bacterial strain than with the simple
presence or absence of a pathogen in cultured sputum. Most
striking was the case of Haemophilus
influenzae; the presence or absence of this pathogen in sputum
was not related to the risk of an exacerbation, but the presence of
a new strain of the organism was.
Finally, should the results of the study by Sethi et al. change clinical
practice?
Probably not, since the findings support the
current empirical use of antibiotics to treat exacerbations of chronic
obstructive pulmonary disease and illustrate the difficulties
in interpreting the results of routine sputum cultures. The study does, however,
point to a major gap in our knowledge namely, which antibiotics should
be used. The studies demonstrating the efficacy of antibiotics are old and
involved the use of inexpensive agents with a relatively narrow spectrum.
Bacterial resistance to these antibiotics has increased, and expensive,
broad-spectrum agents are often used now, though there is little evidence
that they have superior benefits.