keywords: asthmatic, reactive airway disease, wheeze, bronchiolitis, bronchial asthma, acute asthma, allergies, bronchial airways, bronchial airway narrowing, inflammation of the bronchi, bronchial smooth muscle contraction, wheezing, dyspnea, airway narrowing, noisy breathing, difficult breathing, difficulty breathing
Asthma Symptoms & Signs
wheezing
usually begins suddenly
is episodic
may be worse at night or in early morning
aggravated by exposure to cold air
aggravated by exercise
aggravated by heartburn (reflux)
resolves spontaneously
relieved by bronchodilators (drugs that open the airways)
cough with or without sputum (phlegm) production
shortness of breath that is aggravated by exercise
breathing that requires increased work
intercostal retractions (pulling of the skin between the ribs when breathing)
Emergency symptoms:
extreme difficulty breathing
bluish color to the lips and face
severe anxiety
rapid pulse
sweating
decreased level of consciousness (severe drowsiness or confusion) during an asthma attack
Additional symptoms that may be associated with this disease:
nasal flaring
chest pain
tightness in the chest
abnormal breathing pattern, in which exhalation (breathing out) takes more than twice as long as inspiration (breathing in)
breathing which temporarily stops
coughing up blood
Clinical Features: The most characteristic features of Asthma are--- breathlessness, cough and wheezing. The attack often occurs at night but may also occur abruptly due to one of the precipitating factors mentioned above.
The patient often experiences a tight sensation in the chest along with dry cough. Sometimes a long standing dry cough maybe the only indication of Asthma.
Physical:
Accessory muscle use
Ability to lie flat: Patients with mild acute asthma are able to lie flat. In more severe cases, the patient assumes a sitting position. As the severity increases, the patient increasingly assumes a hunched-over sitting position with the hands supporting the torso, termed the tripod position. If symptomatology becomes more severe, profuse diaphoresis occurs. The diaphoresis presents concomitantly with a rise in PCO2 and hypoventilation. In the most severe form of acute asthma, the patient may struggle for air and/or be bradypneic and be profusely diaphoretic; almost no breath sounds may be heard, and the patient is willing to lie recumbent.
Ability to speak/staccato speech
Central cyanosis
Level of alertness
Presence or absence of peripheral edema
Stridor
Subcutaneous emphysema
Bilateral breath sounds
Wheezing: Inspiration-expiration ratio reveals prolongation of the expiratory phase (eg, 1:1 mild, 1:3 severe).
Air entry: In children, assess supraclavicular and intercostal retractions, accessory muscle use, and nasal flaring.
Emergency Department Care:
The mainstay of therapy for acute asthma in the ED is inhaled beta2-agonists. The most effective particle sizes are 1-5 microns. Larger particles are ineffective because they are deposited in the mouth and central airways. Particles smaller than 1 micron are too small to be effective since they move in the airways by Brownian motion and do not reach the lower airways.
Standard delivery systems and routes are as follows:
Albuterol 7.5 mg inhaled over 60-90 minutes divided tid. Dilution of 2.5 mg in 3 mL of saline or use of premixed nebules is standard. Oxygen or compressed air delivery of the inhaled beta-agonists should be at a rate of 6-8 L/min. For children, use 0.15 mg/kg every 20 minutes for 3 doses.
An equivalent method of beta-agonist delivery is the MDI, which has a standard 90 mcg of drug per inhalation and is used in conjunction with a spacer or holding chamber. The dose is 6-8 puffs into the spacer, which is then inhaled by the patient. For most patients who respond to the first treatment, hourly treatments at the same dose are effective. If the patient has a poor response to the MDI/holding chamber, an increase in treatment frequency to every 30 minutes is warranted. The advantage of the MDI/holding chamber is that it requires little or no assistance from the respiratory therapist; the patient can be discharged from the ED with the same spacer and albuterol canister. This modality is especially effective in areas where patients may be unable to afford their inhaled beta-agonists.
Continuous nebulization may be superior to the MDI/holding chamber method in a patient with PEFR less than 200 L/min. The dose of albuterol is 5-15 mg in 70 mL of isotonic saline. For children, this method is reserved for severe asthma at an albuterol dose of 0.3-5 mg/kg/h. Based on meta-analyses, there is no advantage of intravenous albuterol over inhaled albuterol, even in severe asthma.
Metabolic effects include a slight tendency toward tachycardia. Many patients who present with tachycardia and acute asthma actually decrease their heart rate with inhaled beta-agonist therapy. Also, inhaled beta-agonists decrease potassium by an average of 0.4 mEq/L.
Patients who respond poorly or not at all to an inhaled beta-agonist regimen usually respond to parenteral beta 2-agonists, such as 0.25 mg terbutaline or 0.3 mg of 1:1000 concentration of epinephrine administered subcutaneously. This is the treatment of choice, along with continued beta-agonist/anticholinergic therapy, if bronchospasm does not improve after 2-3 treatments with inhaled beta2-agonists and the patient is seriously ill.
Ipratropium 0.5 mg has had variable benefit in controlled trials demonstrating most consistent efficacy in children and smokers. The NAEPP guidelines of 1997 recommend its use in acute asthma exacerbations.
For severe asthma, magnesium has been shown to be beneficial (see Cochrane review) with 2 g over 30 min often recommended. However, higher and faster doses have been effective in asthma and demonstrated safety has been shown for almost 50 years in the obstetrics literature with rates as high as 1 g/min for 3g.
Intravenous leukotriene antagonists can be recommended at this time (montelukast) 7 mg IV (not available currently and in phase III studies), or 10-20 mg orally may produce a prompt dramatic increase in FEV1 in severe ED asthmatics.
In severe asthmatics, to avoid intubation, many of these therapies including inhaled albuterol, ipratropium, steroids, magnesium, parenteral terbutaline, and leukotrienes are administered simultaneously. Which, if any, are effective at that time is difficult to discern.
Endotracheal intubation, once achieved, requires careful ventilation in an asthmatic because of the risk of high pressures lowering systemic blood pressure (auto-PEEP) and less common circumstances of barotrauma, pneumothorax, or pneumomediastinum. It is the better initial response to assess auto-PEEP and disconnect the patient from the ventilator (as tolerated by the patient's oxygenation) than immediately and blindly decompress the chest for a presumptive pneumothorax. One often will induce a pneumothorax, possible under pressure, under these circumstances by needling an overexpanded lung and the chest tube insertion with the unrelieved auto-PEEP will give a rush of air (falsely leading the physician to believe he has relieved a tension pneumothorax) without clinical improvement.
In general, 3-4 hours in the ED is adequate time to determine if patients with acute asthma can improve symptomatically and demonstrate pulmonary flow rates sufficiently improved for safe discharge from the ED. To allow time for glucocorticoids to take effect, extended treatment in a clinical holding area has been demonstrated to be effective. Such units have avoided 60% of admissions to the hospital for acute asthma by treating and observing the patient for as long as 12 hours. These units are appropriate if nursing care and monitoring are adequate. They provide an excellent site for specialized asthma education.
In one holding unit, asthma study patients were discharged within 12 hours at 50% of predicted PEFR if they had no high-risk relapse factors (see list above) or at 60% of predicted PEFR if they had one or more high-risk relapse factors. At time of discharge, patients were given albuterol inhalers and prednisone tablets, avoiding delay and inconvenience of filling the prescriptions and possible noncompliance. At 2 weeks following the ED visit, a 9% relapse rate was noted, considerably less than the 20% for most EDs.
Inability to obtain medications due to socioeconomic factors should lower the threshold for hospital admission for patients who have asthma and PEFR of 50-70% of predicted or personal best rate.
The goals of therapy are to maintain SaO2 greater than 92% and treat dehydration if it is clinically apparent.
Antibiotics should be administered only if bacterial sinusitis, bronchitis, or pneumonia is suspected clinically. Asthma exacerbation severity and therapeutic choices instituted should be evaluated according to the percent of predicted FEV1 or PEFR.
Drug Category: Glucocorticoids -- These anti-inflammatory agents restore the beta2-agonist receptors in the bronchial smooth muscles and, therefore, restore the response to beta2-agonists.
Glucocorticoids are indicated if response to the first or second beta2-agonist inhaler treatment is incomplete.
Additional high-risk patients for whom steroids may be recommended are those who require frequent ED visits, have been admitted with asthma exacerbations, have been intubated, are already on outpatient steroids, or have been experiencing an episode for longer than 3 days.
The onset of action of steroids is approximately 4 h in children and 6 h in adults. Bioavailability of orally and parenterally administered steroids is no different.
Methylprednisolone (Solu-Medrol, Depo-Medrol) -- For treatment of inflammatory and allergic reactions. By reversing increased capillary permeability and suppressing PMN activity, may decrease inflammation. Depo-Medrol is long-lasting and avoids compliance issues and financial issues, which may affect patients' ability to obtain outpatient glucocorticoids.
Adult Dose 80-125 mg IV
Pediatric Dose Loading dose: 2 mg/kg IV
Maintenance dose: 0.5-1 mg/kg/dose IV q6h for up to 5 d
Contraindications Documented hypersensitivity; viral, fungal, or tubercular skin infections
Interactions Coadministration with digoxin may increase digitalis toxicity secondary to hypokalemia; estrogens may increase levels; phenobarbital, phenytoin, and rifampin may decrease levels (adjust dose); monitor patients for hypokalemia if taking concurrent diuretics
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions Hyperglycemia, edema, hypokalemia, euphoria, psychosis, myopathy, and infections are possible complications
Drug Name
Prednisone (Deltasone, Orasone, Meticorten) -- Useful in treatment of inflammatory and allergic reactions. By reversing increased capillary permeability and suppressing PMN activity, may decrease inflammation.
Adult Dose 40-60 mg PO (often administered once in ED in place of IV/IM glucocorticoids) followed by discharge from hospital with 40 mg/d for 5 d; most effective if ingested at about 3 pm
Pediatric Dose 4-5 mg/m2/d PO; alternatively, 1-2 mg/kg PO qd
Contraindications Documented hypersensitivity, viral infection, peptic ulcer disease, hepatic dysfunction, connective tissue infections, fungal or tubercular skin infection, GI disease
Interactions Coadministration with estrogens may decrease clearance; concurrent use with digoxin may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics
Pregnancy B - Usually safe but benefits must outweigh the risks.
Precautions Abrupt discontinuation may cause adrenal crisis; adverse effects include hyperglycemia, edema, myopathy, hypokalemia, euphoria, psychosis, myasthenia gravis, and infections
Drug Name
Triamcinolone (Aristocort) -- Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing capillary permeability.
Adult Dose 60 mg IM, followed by additional doses of 20-100 mg IM; doses given when signs and symptoms recur
Pediatric Dose <6 years: Not recommended
6-12 years: 0.03-0.2 mg/kg IM at 1- to 7-d intervals
>12 years: Administer as in adults
Contraindications Documented hypersensitivity; fungal, viral, and bacterial skin infections
Interactions Coadministration with barbiturates, phenytoin, or rifampin decreases effects
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions Multiple complications (eg, severe infections, hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression) may occur; abrupt discontinuation may cause adrenal crisis
Drug Name
Albuterol (Proventil, Ventolin) -- Bronchodilator in reversible airway obstruction due to asthma. Relaxes bronchial smooth muscle by action on beta2-receptors with little effect on heart rate.
Adult Dose 7.5 mg INH over 60-90 min divided tid; dilute 2.5 mg in 3 mL of saline or use premixed nebules
Pediatric Dose 0.15 mg/kg INH q20min for 3 doses
Contraindications Documented hypersensitivity
Interactions Beta-adrenergic blockers antagonize effects; inhaled ipratropium may increase duration of bronchodilatation; cardiovascular effects may increase with MAOIs, inhaled anesthetics, tricyclic antidepressants, or sympathomimetic agents
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions Caution in hyperthyroidism; excessive use may result in tolerance and hypokalemia and hypomagnesemia; adverse reactions may occur more frequently in children aged 2-5 y
Drug Name
Epinephrine (EpiPen, Adrenaline, Bronitin) -- Alpha-agonist effects increase peripheral vascular resistance and reverse peripheral vasodilatation, systemic hypotension, and vascular permeability. Beta-agonist activity of epinephrine produces bronchodilatation.
Adult Dose 0.01 mL/kg SC; not to exceed 0.3-0.5 mL (0.3-0.5 mg) of 1:1000 solution
Pediatric Dose Not established
Contraindications Documented hypersensitivity, cardiac arrhythmias, angle-closure glaucoma, use as local anesthetic in areas such as fingers or toes (vasoconstriction may produce sloughing of tissue); use during pregnancy (decreases uterine blood flow causing uteroplacental insufficiency)
Interactions Increases toxicity of halogenated inhalational anesthetics
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions Rapid IV infusions may cause death from cerebrovascular hemorrhage or cardiac arrhythmias; caution in elderly and hyperthyroidism
Drug Name
Terbutaline (Brethaire, Bricanyl) -- Selective beta2-agonist acts directly on beta2-receptors, relaxing bronchial smooth muscle, relieving bronchospasm, and reducing airway resistance.
Adult Dose 0.25 mg SC; repeat q15-30 min prn
2 puffs MDI q4-6h
5 mg PO tid; not to exceed 15 mg/d
Pediatric Dose <12 years: 0.25 mg SC; repeat q15-30min prn; 2 puffs MDI q4-6h; 0.05 mg/kg/dose PO tid, not to exceed 5 mg/d
>12 years: Administer as in adults
Contraindications Documented hypersensitivity, tachycardia resulting from cardiac arrhythmias
Interactions Concomitant beta-blockers may inhibit bronchodilating, cardiac, and vasodilating effects of beta-agonists; concomitant MAOIs may result in hypertensive crisis; concurrent oxytocic drugs such as ergonovine may result in severe hypotension
Pregnancy B - Usually safe but benefits must outweigh the risks.
Precautions Through intracellular shunting, terbutaline may decrease serum potassium levels, which can produce adverse cardiovascular effects; decrease is usually transient and may not require supplementation
Drug Name
Ipratropium (Atrovent) -- Chemically related to atropine, has antisecretory properties. When applied locally, inhibits secretions from serous and seromucous glands lining nasal mucosa.
Adult Dose Nebulizer: 1 unit dose vial (500 mcg) INH tid/qid, with doses 6-8 h apart
MDI: 2 INH qid; not to exceed 12/d
Pediatric Dose 0.25-0.50 mg INH after first dose of beta2-agonist inhaler
1997 NAEPP guidelines recommend 0.25 mg INH q20min for 3 doses, then q2-4h prn, or by MDI 4-8 puffs
Contraindications Documented hypersensitivity
Interactions Drugs with anticholinergic properties, such as dronabinol, may increase toxicity; albuterol increases effects
Pregnancy B - Usually safe but benefits must outweigh the risks.
Precautions Not indicated for acute episodes of bronchospasm; caution in narrow-angle glaucoma, prostatic hypertrophy, and bladder neck obstruction
Drug Name
Ipratropium and albuterol (Combivent) -- Ipratropium is chemically related to atropine. It has anti-secretory properties and, when applied locally, inhibits secretions from serous and seromucous glands lining the nasal mucosa.
Albuterol is a beta-agonist for bronchospasm refractory to epinephrine. Relaxes bronchial smooth muscle by action on beta2-receptors with little effect on cardiac muscle contractility.
Recommended to "test spray" 3 times before using first time and in cases where aerosol has not been used for >24 h.
Adult Dose 2 INH qid; may take additional INH prn; not to exceed 12 INH/24 h
Pediatric Dose Not established
Contraindications Documented hypersensitivity
Interactions Drugs with anticholinergic properties (eg, dronabinol) may increase toxicity; albuterol increases effects of ipratropium
Beta-adrenergic blockers antagonize effects; inhaled ipratropium may increase duration of bronchodilatation by albuterol; cardiovascular effects may increase with MAOIs, inhaled anesthetics, tricyclic antidepressants, and sympathomimetic agents
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions Caution in hyperthyroidism, diabetes mellitus, and cardiovascular disorders; caution in narrow-angle glaucoma, prostatic hypertrophy, and bladder neck obstruction
Drug Name
Theophylline (Theo-Dur, Theo-24, Aminophylline) -- Purported efficacy thought to be due to potentiation of exogenous catecholamines, stimulation of endogenous catecholamine release, and diaphragmatic muscular stimulation.
Effects as bronchodilator are mild, and toxicity (levels >20 mg/dL) is common.
Adult Dose Loading dose: 6 mg/kg lean body weight IV over 20-30 min
Drip (1 g in 250 mL D5W): 0.5-0.7 mg/kg/h IV
Pediatric Dose 1 mg/kg/h IV
Contraindications Documented hypersensitivity, uncontrolled arrhythmias, peptic ulcers, hyperthyroidism, uncontrolled seizure disorders
Interactions Aminoglutethimide, barbiturates, carbamazepine, ketoconazole, loop diuretics, charcoal, hydantoins, phenobarbital, phenytoin, rifampin, isoniazid, and sympathomimetics may decrease effects; effects may increase with allopurinol, beta-blockers, ciprofloxacin, corticosteroids, disulfiram, quinolones, thyroid hormones, ephedrine, carbamazepine, cimetidine, erythromycin, macrolides, propranolol, and interferon
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions Caution in hyperthyroidism; do not inject IV solution faster than 25 mg/min; patients with pulmonary edema or liver dysfunction at greater risk of toxicity because of reduced drug clearance
Drug Name
Ketamine (Ketalar) -- Acts on cortex and limbic system, decreasing bronchospasm. A dissociative anesthetic agent.
Adult Dose Initial dose: 1-4.5 mg/kg IV
Maintenance dose: One third to one half initial dose IV
Pediatric Dose Initial dose: 0.5-2 mg/kg IV
Maintenance dose: One third to one half initial dose
Contraindications Documented hypersensitivity; thyrotoxicosis
Interactions Increases CNS effects of narcotics, barbiturates, and hydroxyzine; thyroid hormones and muscle relaxants increase toxicity
Pregnancy D - Unsafe in pregnancy
Precautions Caution in patients with intracranial hypertension; may increase bronchial secretions, prompting some practitioners to administer concomitant antisecretory agent (ie, glycopyrrolate) routinely as preventive measure
Resuscitative equipment should be immediately available when administering this medication
Drug Category: Inhaled volatile anesthetics -- These agents may aid in smooth muscle relaxation.Drug Name
Halothane (1-2%) -- Leads to moderate effects on bronchial muscular relaxation and causes bronchodilation.
Adult Dose 24 years: 0.84 MAC
42 years: 0.76 MAC
81 years: 0.64 MAC
Pediatric Dose Infants: 1.08 MAC
3 years: 0.91 MAC
10 years: 0.87 MAC
15 years: 0.92 MAC
Contraindications Documented hypersensitivity
Interactions Caution when administering epinephrine or norepinephrine
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions Hepatic dysfunction may occur
2006-07-16 19:53:19
·
answer #10
·
answered by Justin L 1
·
0⤊
0⤋