athsma why?

Introduction to Asthma Diagnostics and Monitoring

  • Focus on diagnostic and monitoring tests for asthma.

FEV1 and Diagnosis

  • FEV1 Change:

    • An increase of greater than or equal to 12% or 200 milliliters after administration of a bronchodilator (typically albuterol, a short-acting beta agonist, SABA) indicates reversible airflow limitation consistent with asthma.

    • Note on COPD: COPD is also an obstructive disease but lacks this reversibility characteristic.

    • Potential future change in guidelines may lower the threshold for FEV1 change to greater than or equal to 10%, though this has not yet been implemented.

FEV1/FVC Ratio

  • FEV1/FVC ratio or FEV1 percentage is crucial for diagnosing airflow limitation:

    • It helps differentiate between restrictive and obstructive processes.

    • Normal Range: Typically a ratio greater than 0.75 to 0.80.

    • Values below this indicate an obstructive process.

    • Asthma is considered reversible while COPD is not.

Peak Expiratory Flow Rate (PEFR)

  • Criteria for Asthma Diagnosis:

    • Improvement of 60 liters per minute or greater than or equal to 20% of pre-bronchodilator peak flow post-bronchodilator.

    • Diurnal variation of more than 20% with morning and evening recordings.

    • Pre and post bronchodilator measurements must be taken around the same time each day for accuracy.

Bronchopulmonary Challenge Tests

  • Methodology for Testing:

    • Use of agents such as methacholine, histamine, or mannitol.

    • Exercise in cold air can also be utilized as a challenge if the patient shows symptoms upon these stimuli.

Allergy Testing

  • RAST (Radioallergosorbent Test):

    • Skin prick tests done on the forearm to test for allergens like tree pollen, animal dander, etc.

    • Reaction signifies a positive test indicating an allergen is a trigger for the patient.

Exhaled Nitric Oxide (FeNO) Testing

  • Values for Diagnosis:

    • An exhaled nitric oxide level greater than 25 parts per billion indicates eosinophilic airway inflammation, common in extrinsic or atopic asthma.

    • Levels greater than 50 parts per billion may necessitate an increase in controller medication.

Asthma-COPD Overlap Syndrome (ACOs)

  • Evaluation factors:

    • Lung function tests, medical history, and chest x-ray findings are critical in distinguishing asthma from COPD.

    • Note: Asthma may show normal x-ray during an exacerbation, while COPD rarely shows normal findings.

Management of Asthma

  • Therapeutic Approaches:

    • Differentiate between acute management and ongoing pharmacological therapy.

    • Access guidelines through GINA (Global Initiative for Asthma).

Noninvasive and Mechanical Ventilation

  • Indications:

    • Noninvasive ventilation (like BiPAP) for patients nearing respiratory failure, while mechanical ventilation may be needed in severe cases.

  • Acute Intervention Criteria:

    • Significant respiratory failure indicated by a pH around 7.2.

Specific Medications & Treatments

  • Initial Treatments:

    • SABA: Albuterol for immediate bronchoconstriction relief.

    • Systemic Corticosteroids: To address inflammation during exacerbations. Administered intravenously if the patient is severely short of breath.

    • Bronchodilators fail during late-phase inflammation.

  • Oxygen Therapy: Ensuring appropriate SpO2 levels, typically less restricted in younger populations.

  • Continuous Albuterol Infusion: Between 5 to 20 milligrams per hour during treatment.

  • Heliox: A mix of helium and oxygen may be used to facilitate delivery of medication past airway obstructions.

  • Magnesium Sulfate and Low Dose Ketamine: Used as adjunct therapies to relax smooth muscle during exacerbations.

Pharmacological Management Strategies

  • Long-Acting Beta Agonists (LABA):

    • Typically formoterol, used in conjunction with inhaled corticosteroids (ICS).

  • Inhaled Corticosteroids (ICS):

    • Should be a staple in asthma management, both for inflammation control and preventing exacerbation. Should be given as soon as possible for effective management.

Upregulation of Receptors

  • Importance of Systemic Corticosteroids:

    • They increase the number and affinity of beta-2 receptors, mitigating the downregulation that occurs due to frequent beta agonist use.

Leukotriene Receptor Antagonists (LTRAs)

  • Anti-inflammatory effects targeting leukotriene pathways.

    • Vary by drug, blocking either all or specific leukotrienes.

Education and Patient Involvement

  • Patient Education Involves:

    • Understanding medications, triggers, maintenance plans, and when to seek help.

    • Use of asthma journals to track symptoms and peak flow readings for better self-management.

  • Peak Flow Zones:

    • Green Zone: No action required.

    • Yellow Zone: Indicate need for SABA.

    • Red Zone: Urgent medical attention needed.

Comorbidities Management

  • Consider factors like obesity and gastroesophageal reflux disease (GERD) that can affect asthma control.

Lifestyle Recommendations

  • Encouragement of Physical Exercise: Requires patient mobility to prevent complications in hospitalization.

  • Hydration: Important for maintaining proper mucus viscosity.

  • Dietary Considerations: Minimize processed foods, optimize omega-3/-6 balance, and ensure adequate hydration for asthma management.

Summary of Important Testing

  • PFTs (Pulmonary Function Tests): Initial diagnosis and monitoring.

  • Sputum Induction Test: For microscopic analysis of exacerbations and eosinophilia.

  • CBC and Differential Counts: To assess white blood cell responses specific to asthma, especially eosinophil counts.

  • Follow-Up Tests: Including FeNO, chest x-rays, and peak flow testing.

Conclusion

  • These comprehensive strategies for managing asthma patients must be consistently utilized and personalized based on individual patient needs, with emphasis on education, monitoring, and responding to symptoms effectively.