Asthma

HISTORY

Sx: Mode of onset, setting in which occurred. Manifestations - ChLoRIDE PP.

• • SOB, cough, wheeze – daytime/nighttime frequency?

  • Activity limitations?

  • Frequency in use of rescue inhalers?

  • Any post-nasal drip/GERD symptoms?

• Any ED visits/hospitalizations/ICU admission/intubations since last visit?

  • Number of yearly ED visits/hospitalizations/ICU admission/intubations

  • Any history of seizures during asthma?

  • Current maintenance therapy and rescue therapy.

  • Compliance with medicaitons and appropriate f/up

• Known triggers

  • Exposure to cigarette smoke (sensitization in childhood - passive smoker), wood smoke (barbeque lovers)

    • Any exposure to animal dander/cockroaches/dustmites/pollen/molds/fragrances or perfumes/detergents.

    • Sesasonal onset exposure to pollen, ragweed, grass, molds.

  • Any carpeting in the room, mattress box not wrapped in plastic, feather pillow?

  • Cold air, strong emotional stimuli, and exercise.

  • Viral upper respiratory infections.

  • Medications such as BB (including ophthalmic), aspirin, NSAIDS,

    • Pts with ASA sensitivity and nasal polyps usually have asthma onset in their 30s or 40s.

  • Baseline Peak Flows

  • Any PFTs in the past?

  • Last systemic steroids use

• Last Pneumovax and flu shot

• Last influenza vaccination.

• Any childhood illnesses (RSV and rhinovirus)

• Any h/o OSA?

• FH of atopy.

Pt. >50 years old or with >20 pack years of smoking presenting with SOB is less likely to be asthma as the cause of respiratory symptoms.

PHYSICAL EXAM

• • Peak Flows – each visit if patient brings in their meter.

• General – shortness of breath, unable to speak in full sentences, level of consciousness, accessory respiratory muscle use.

  • Ears – tympanic membrane

  • Sinuses - tenderness

  • Nose – enlarged turbinates, polyps, rhinitis

  • Throat and Oral Cavity – posterior pharyngeal wall erythema or exudates

  • Lungs – Inspiratory/expiratory wheezes, rhonchi, signs of consolidation. Silent chest with Pt in respiratory distress may be a sign of severity of disease.

  • Subcutaneous emphysema signifies presence of PTx or pneumomediastinum.

• Abdomen – epigastric tenderness

INVESTIGATIONS

• Routine lab test not needed for dx; should not delay in initiating treatment.

• Peak Flows – each visit if patient brings in their meter. Peak expiratory flow rate (PEFR) is the greatest flow velocity that can be obtained during a forced exhalation starting with the lungs fully inflated. It is important to observe the patient during the peak flow maneuver to determine if a maximum effort is being expended. If not, the measurement is unreliable and should be discarded.

  • PEFR in men: 500 - 700 L/min

  • PEFR in women: 350 - 500 L/min

  • PEFR in both sexes is 10 - 20% lower at age 70 than at age 20.

  • PEFR is lowest early morning.

  • The personal best PEFR is obtained when the Pt is free of sx.

• PFTs: Pt's baseline.

  • essential to Dx; demonstrates obstructive pattern as decrease in expiratory flow rates:

    • FEV1/FVC ratio <0.75. Normal ratio in mild disease with only abnormality being decrease in midlung volumes (forced exp flow 25 - 75% is lowered).

    • Obstructive pattern improves after bronhodilator therapy; FEV1 improves by 12% and 200 cc after 2 - 4 puffs of short acting bronchodilator. Most patients will not demonstrate reversibility at each assessment.

    • A methacholine challenge is done when spirometry is normal. It is considered positive when a provocative concentration of 8 mg/mL or less causes a drop in FEV1, of 20% (PC₂₀)

  • The severity of exacerbation should be classified accordingly.

    • Mild (PEF or FEV1 > 70% of predicted or personal best)

    • Moderate (PEF or FEV1 40% - 69%)

    • Severe (PEF or FEV1 < 40%), or

    • Life-threatening/impending respiratory arrest (PEF or FEV1 < 25%).

  • In chronic severe asthma, airway reversibilty may no longer be completely reversible. In such patients the most effective way to demonstrate reversibility is by repeating PFTs after a course of oral corticosteroids (usually 40 mg/day x 10 days). The lack of demonstrable airway obstruction or reactivity does not rule out a diagnosis of asthma.

• CXR – baseline. Routine not needed. Done if complicating process such as pneumonia or PTx is suspected or to rule out other causes that may present as asthma.

• HRCT of chest using PE protocol in patients with severe asthma refractory to treatment.

• ABG in Pts with severe distress or with an FEV1 or PEF <40%.

  • PaO2 <60 mm Hg signifies severe bronchospastic disease or complicating condition, such as pulmonary edema or penumonia.

  • PaCO2: normal or >40 mm Hg signifies severe airway obstruction, increased dead space ventilation, and respiratory muscle fatigue leading to impending respiratory failure. Patient needs ICU admission.

Tx:

• Asthma action plan: chronic management and acute exacerbations management.

• When initiating therapy for a patient not on controller medication, assign severity level based on any feature that has occurred over the previous 2 - 4 weeks.

• Assessment of control on subsequent visit for patient already on controller medication.

• Response to initial treatment ( 3 treatments every 20 min with SABA) is a better predictor of the need for hospitalization than is the severity of an exacerbation.

• Bronchodilator Need: The PEFR can help by providing a bedside test of bronchodilator responsiveness. The PEFR can be recorded just before, and again 20 minutes after, a bronchodilator aerosol treatment. If the PEFR increases by 15% or more after the treatment (indicating a favorable response), then therapy with bronchodilator aerosols can be continued. If the post-bronchodilator PEFR does not change or increases by less than 10% (indicating a poor response), inhaled bronchodilators are not justified. The test must be done more than once to add validity to the results.

• In Pt. on mechanical ventilation bronchodilator benefit decreases the PIP (positive inspiratory pressure) and also auto-PEEP.

• SABA (albuterol), LABA/ICS.

• Patients d/c from ED should get oral CS, prednisone, 40 mg qd x 5 - 7 days.

• LTM. LTRAs (Montelukast 10 mg PO daily, Zafirlukast 20 mg PO bid). Zileuton ER 1200 mg PO bid is an oral 5-lipoxygenase inhibitor. LTMs are strongly recommended for patients with ASA induced asthma or Pt who can't use MDIs.

• Anti-IgE therapy

  • Omalizumab is a monoclonal ab against IgE. that is approved in patients who have moderate to persistent asthma due to perennial aeroallergens, and incomplete control with ICS. Administered SC q2-4 wk, is dose based upon the patient's baseline IgE level (between 30 - 700 IU/mL) and weight.

• Methylxanthines: Theophylline SR at low doses 300 mg/day, for control of nocturnal attacks.

• Magnesium sulfate, IV. Severe exacerbation refractory to standard treatment x 1 hour. Magnesium sulfate, 2 g IV over 20 minutes x 1 dose in the ED should be considered.

• Inhaled Heliox: Severe exacerbation refractory to standard treatment x 1 hour, heliox-driven albuterol neb in a mixture with oxygen 70:30 is considered.

• Mechanical Ventilation may be required in respiratory failure:

  • Chose large ETT > 7.5 mm, low Vt, prolonged exp time with high insp flow and low resp rate. In some Pts. permissive hypercapnia with a goal to avoid hyperinflation, autoPEEP.

• Lifestyle risk modification:

  • Diet: avoid sulfites (beer, wine, processed potatoes, dried fruit)

  • Activity: Exercise. If exercise is a trigger, give prophylactic LTM or albuterol 2 - 4 puffs 20 min prior to exercise.

• Patients with ASA sensitivity and nasal polyps typically have onset of asthma in their 30s or 40s.

Complications:

• SABA: Sympathomimetic-type (tremor, anxiety, tachycardia), decrease in serum potassium and magnesium, mild lactic acidosis, prolonged QT.

• ICS

  • Increased risk of systemic effect at high doses (>1000 mcg of beclomethasone daily), skin bruising, cataracts, elevated IOP, and accelerated loss bone mass.

  • Pharyngeal and laryngeal effects are common such as sorethroat, hoarse voice, and oral candidiasis.

  • Patients should be instructed to rinse their mouths after each administration to reduce the possibility of thrush.

• LABA should only be used in combination with ICS.

• LTM

  • Cases of newly dx Churg-Strauss vasculitis after exposure to LTRA have been described. Inconclusive.

  • Zileuton can cause a reversible hepatitis. Check baseline LFTs prior to initiating treatment. Monitor LFTs q mo x 3 mo, then q3 mo x 1 yr, and then periodically.

• Omalizumab (anti-IgE) therapy: Anaphylaxis in 1 to 2 per 1,000, usually within 2 hours of the first doses. Patients should be observed 2 hours after initial doses and then 30 min for subsequent dosing as well as possess self-administered epinephrine (Epipen) for 24 hours after each dose.

• Methylxanthines

  • Theophylline has a narrow therapeutic window and has significant toxicities, such as arrhythmias and seizures, as well as potential drug interactions with antibiotics.

  • Serum concenteration of theophylline is monitored on a regular basis, maintaining a level of 5 - 10 mcg/mL.

Patient education:

• Symptoms based asthma action plans are equivalent to PEF-based plans in terms of overall self-management and control.

  • The personal best PEF is identified (the highest PEF obtained when the disease is under control), and PEF is checked when sx escalate or in the setting of an asthma trigger. This is incorporated into an asthma action plan, setting 80% - 100% of personal-best PEF as the "green" zone, 50% - 80% as the "yellow" zone, and < 50% as "red" zone.

• Monitoring sx is more effective than relying on PEF.

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