BRONCHIAL ASTHMA

• Main diagnostic criteria for bronchial asthma is reversibility of airflow obstruction which is demonstrated by spirometry.

                             

SPIROMETER :

• Patient is made to perform forceful inspiration and expiration and flow volume curves are obtained

• Baseline curve for inspiration part remain same but expiration part patient is not able to push out the air as asthma is disease of expiratory. so, marked concavity in expiration part is present
• Now salbutamol is given and test is repeated in 10 - 15 min, concavity will reduce significantly (see above)
• FEV1 decreased ⟶⟶ after S.A.B.A (short acting beta2 agonist) ➝➝ FEV1 normal

• Methacholine provocation test : It is of historical importance. not done now as may lead to imminent respiratory failure.

• Eucapnic hyperventilation test : Person is made to breathe in cold air. asthmatics has bronchial hyper reactivity to cold air and FEV1 will fall

DIAGNOSTIC CRITERIA :

• Reversibility (Absolute criteria): asthma is reversible airflow obstruction disease
• Asthma is episodic
• Most attacks are nocturnal. possible explanation is  that at night time air is cold
• Main test for diagnosis is spirometry
• Chest x - ray may show hyperinflation and flattening of diaphragm or it can be normal also, so it has no role in diagnosis asthma
• No role of HRCT chest in diagnosis of asthma
• Allergic bronchopulmonary aspergilloma - Hypersensitivity reaction to aspergillus fumigatus which is associated with central bronchiectasis. steroids and itraconazole are given as treatment

GINA 2019 (Global initiative for asthma)

• New studies have suggested that patients treated only with salbutamol (SABA) are found to have higher asthma related death incidence
• Controller - Prevention : low dose inhaled corticosteroid (ICS) with formoterol
• Reliever - low dose inhaled corticosteroid (ICS) with formoterol

• Earlier - SABA (short acting beta2 agonist)

• Steroids given in both conditions as it treat the disease by inhibiting enzyme phospholipase A2 and decreases release of Leukotrienes.

Controller :

• Intermittent asthma :

 Symptoms < 2days/week 

Interference - none

FEV1 - Normal (>80%)

Treatment - STEP 1

• Mild persistent asthma :

Symptoms > 2days/week

Interference - none

FEV1 - Normal

Treatment - STEPS 2

• Moderate persistent asthma :

Symptoms - Daily

Interference - Some limitation

FEV1 - 60 -80%

Treatment - STEPS 3

• Severe persistent asthma :

Symptoms - All through day

Interference - Extreme limitation

FEV1 - < 60%

Treatment - STEPS 4 or 5

• STEP 1 : Low dose ICS(budesonide) with formoterol as needed, patient advised to rinse his mouth with water to minimize risk of oropharyngeal candidiasis.
• STEP 2 : Low dose ICS(Daily) - should be continued at least for next 3 - 6 months. formoterol when required
• STEP 3 : Low dose ICS + LABA daily
• STEP 4 : Medium dose ICS + LABA
• STEP 5 : High dose ICS + LABA + add on therapies

- Sputum microscopic examination : Eosinophils > 3% indicates requirement of up gradation of therapy

- Sputum guided therapy is used to done standardization of therapy

Add on :

- Tiotropium - Long acting muscarinic agents (LAMA) - anticholingeric

- Omalizumab - Anti IgE given subcutaneously

- Mepolizumab - Anti IL - 5/5R

- Dupilumab - Anti IL - 4/4R (useful in severe type 2 asthma)

Acute asthma exacerbation :

PEFR meter is advised (Peak expiratory flow rate) 

- Flow rates can be observed according to age , sex  and height

Management of acute exacerbation :

1. Increase the dose of controller medication - can be increased up to 4 times of normal dose
2. Add S.A.B.A (Salbutamol)
3. Add oral corticosteroids

Mild Exacerbation - FEV1 (> 70%) and PaO2 - Normal

Moderate Exacerbation - FEV1 (40 - 69%) and PaO2 - >60 mm of Hg

Severe Exacerbation - FEV1 (< 40 %) and PaO2 - <60 mm of Hg

Indications of hospitalization :

• Inability to lie in bed
• Cannot speak/ talk
• Patient is drowsy and can't obey commands due to co2 nacrosis
• FEV1 < 25% of predicted valve 
• Post treatment FEV1 < 40%

SEVERE ACUTE ASTHMA ;

1. Talks in words
2. Agitated
3. Tripod position
4. Accessory respiratory muscles used by patient
5. Respiratory rate > 30/min
6. Heart rate > 120/min
7. Pulsus paradoxus +/-
8. Loud rhonchi

TREATMENT : Nebulization with salbutamol, O2 driven (Humidified). done every 20 min in first hour.

• Curschmann spirals are casts of mucus plugs which can block the airways

Disappearance of loud Rhonchi may be indicative of underlying blockage of airways

• Terbutaline subcutaneous
• I.V Hydrocortisone (can also potentiate effect of bronchodilators)
• Consider Mgso4 (magnesium sulphate) - as magnesium antagonize effect of calcium mediated bronchoconstriction.
• Aminophylline +/_ (Toxicity)
• Ipratropium

Imminent Respiratory Arrest :

• Can't talk , silent
• Drowsy due to CO2 narcosis
• > 30 /min Respiratory rate, bradycardia
• Shallow rapid breathing
• Cyanosis
• Pulsus paradoxus disappears

 TREATMENT :

1. Hydration - As neuromuscular blockade for intubation causes vasodilation and severe fall in occur so before intubation I.V fluids should be given to patient.
2. Neuromuscular + E.T tube + Assisted contracted mechanical ventilation (ACMV) - Barotrauma can occur if inspiratory pressure is increased to decrease the pCO2
3. To minimize risk of barotrauma, permissive hypercapnia is allowed pH = 7.3 , pCO2=50 mm Hg

Brittle  Asthma :

Diurnal variation of PEFR > 40%

Epi - PEN is advised to keep along and injected subcutaneously when patient feels attack.

• Permissive hypercapnia is contraindicated in patient with raised ICT as it may cause vasodilation and worsen cerebral edema.
• It is allowed in patient of Imminent respiratory arrest, severe acute exacerbation of COPD.