3. ASTHMA Flashcards
DEFINITION of ASTHMA
Hallmark of asthma
Asthma is a chronic inflammatory airway disease associated with airway irritability and hyper responsiveness leading to respiratory symptoms such as wheezing, shortness of breath, chest tightness and cough. These vary over time and intensity together with variable expiratory airway limitation. It is a common and potentially serious chronic disease imposing a substantial burden on patients and their families and all of us of society.
Definition of asthma exacerbations
Asthma exacerbation’s are defined as episodes of increased breathlessness, cough, wheezing, chest tightness or a combination of the symptoms which may have a progressive or abrupt onset and are always related to decreased expiratory or in severe cases inspiratory air flows
Prevalence of asthma
About one out of 12 Filipinos or 8% are braided by asthma and about 11 out of 100,000 dies from it. Annual mortality rate from asthma increases by 0.1% every year, men being more at risk than women. In children the risk of mortality is equal between both sexes. This underscores the importance of early recognition and management of asthma exacerbations to decrease morbidities and mortalities from this disease
Give the pathogenesis of asthma
On the background of airway hyperresponsiveness and irritability, asthmatics when exposed to allergens, viruses and other chemical mediators which I will discuss later develop airway obstruction brought about by
- bronchoconstriction
- airway thickening due to Mucosal edema,
- increased airway secretions
- inflammation.
Combination of these 4 key factors in asthma eventually leads to —> non-uniform ventilation —> V/Q mismatch. This creates a shunt effect. In turn, there will be a —> significantly decreased alveolar ventilation.
On the other hand, because of expiratory airflow limitation associated with asthma, there will be a trapping —> (+) hyperinflation —> increased compliance of the chest wall. This leads to increased work of breathing
Alveolar hypoventilation together with increased work of breathing —> hypoxia & hypercarbia which induced PULMONARY VASOCONSTRICTION leading to decrease blood flow to the lungs.
—> With decreasing blood flow, lungs me undergo atelectasis or collapse** due to decreased surfactant production** as well as respiratory muscle fatigue**
Give the precipitating factors of Asthma
For precipitating factors, it could be caused by intrinsic or non-IGE mediated factors. Also we have extrinsic or IGE mediated factors. GERD could also be one course and under assessment and port control of asthma could also exacerbate the disease. Examples of intrinsic factors would be called ear, viral respiratory tract infections which could cause mucosal damage and impaired mucocele your clearance. Bacterial infections could release exotoxins or endotoxins. Environmental pollutants or occupational pollutants such as tobacco smoke, wet mean, clearing Asians, greens and flowers, and nauseous fumes. Drugs or medication such as aspirin or NSAIDs could also exacerbate asthma because the inhibit cyclooxygenase pathway in arachidonic acid metabolism causing shift to live oxygenase and EHETEE pathways leading to formation of Luca trains and 5-hetes (eicosanoids) Which are both that bronco constrictors and inflammatory agents.
Extrinsic or IGE mediated factors would include allergen such as dust mites, animal dander (dogs & cats), food (milk, nuts, vegetables, fruits, preservatives and seafood)
Gerd causes direct damage to respiratory epithelium leading to airway spasm. Here risk factors should be investigated such as obesity, caffeine intake, alcohol, fatty and spicy food
Clinical manifestations
Most of the time, patient experiencing an acute asthma exacerbation welcome to the emergency department with a previous diagnosis of partially control, uncontrolled or an unknown control Of asthma.
However, occasionally, an acute exacerbation may be the initial presentation of asthma.
This is the reason why a good history and physical exam must be obtained to come up with the right diagnosis provided that these patients have been relieved of severe respiratory distress and life-threatening conditions be ruled out first.
Even if the patient is a non-asthmatic, other differential diagnosis must also be considered. These include foreign body obstruction and other causes of acute upper airway obstruction including anaphylaxis, pneumothorax, pneumonia or even cardiac dysfunction. Ancillaries may be requested if diagnosis is questionable.
Signs and symptoms of acute asthma exacerbation includes cough, wheezing, shortness of breath and chest tightness.
Coughing usually sounds tight and non-productive early in the course. It is particularly more severe at night or upon waking up in the morning.
Wheezing usually becomes louder as the degree of obstruction increases. However, it may strikingly be absent especially in cases of severe or complete obstruction so the more severe the exacerbation is the Moore Probable that wheezing will not be observed.
Due to breathlessness, patients may only be able to speak in phrases or words and or prefer a sitting or hunched forward and tripod position instead of lying down
Perception of chest tightness may be apparent due to increased work of breathing.
Because of increased respiratory effort and work of breathing, patient’s may sweat profusely and may even have low-grade fever which must be differentiated from infectious causes of respiratory distress
Other signs which may be noted include:
(+) tachypnea, tachycardia
(+) prolonged expiration - d/t premature closure of airway
(+) chest retractions and use of accessory muscles
(+) barrel chest - due to hyperinflation and airway trapping
(+) cyanosis - in cases of extreme hypoxemia
(+) abdominal pain - usually in children d/t strenuous use of abdominal muscles
(+) altered sensorium - drowsiness and lethargy
(+) andominal paradox - when diaphragmatic fatigue has already ensued
(+) pulsus paradoxus - >10 mmHg up to 40 mmHg difference in inspi BP, extremely difficult to perform in children who are in severe respiratory distress
O2 Sat <95% or even <90% in some cases
The better indicators of severity fo airflow obstruction are:
Decreases in lung function measured either by spirometry FEV1 or peak flow meters (PEFR)
It is important to note that FEV1 measurement by spirometry may be difficult or impossible to perform in children who are in severe respi distress
On the other hand, PEFR measurement is a better alternative byt may not be totally representative of the degree of airway obstruction since it only measures those of the larger airways.
In cases where in PEFR shows normal results but the rest of the PE findings reveal otherwise, the results of the latter must be respected.
Chest radiographs (PA Lat) may be requested if potential complications are suspected such as pneumothorax
Things to consider in the DX
The better indicators of severity fo airflow obstruction are:
Decreases in lung function measured either by spirometry FEV1 or peak flow meters (PEFR)
It is important to note that FEV1 measurement by spirometry may be difficult or impossible to perform in children who are in severe respi distress
On the other hand, PEFR measurement is a better alternative byt may not be totally representative of the degree of airway obstruction since it only measures those of the larger airways.
In cases where in PEFR shows normal results but the rest of the PE findings reveal otherwise, the results of the latter must be respected.
Chest radiographs (PA Lat) may be requested if potential complications are suspected such as pneumothorax
Overview of asthma exacerbation management
- Rapid relief of acute asthma attack
- Prevention of recurrence with controller medications
- Arrangement for follow-up and patient education
What to do under
1. Rapid relief of acute asthma attack?
The goals are always to:
- RAPID REVERSAL of AIRWAY OBSTRUCTION
- CORRECTION of HYPOXEMIA
In the primary care setting, if the patient presents with signs and symptoms of acute asthma exacerbation such as shortness of breath, wheezing, cough and chest tightness, you should first assess and confirm if it is really asthma dn rule out other diff fx. Based on signs/symptoms, you should first assess the severity of exacerbation.
Based on the signs and symptoms, you should rapidly assess the severity of exacerbation.
We must be able to recognize a severe or life-threatening asthma exacerbation since these two will require urgent transfer to an acute care facility such as the ER or an ICU for possible intubation and mechanical ventilation.
In severe exacerbations, patient: 1. 2. 3. …
- Only talks in words, sits hunched forward, appears agitated
- RR >30/min, PR >120 bpm
- Accessory muscles in use
- O2 sat <90%
- PEF <50% of predicted or best
In life threatening exacerbations, patient may appear:
- Drowsy/lethargic
- Confused
- Silent chest
It is important to note that while waiting for the patient to be transferred to an acute care facility, we must start giving:
- ) Inhaled SABA **IPRATROPIUM BROMIDE (MDI or nebulization)
- ) SYSTEMIC CORTICOSTEROID (oral or IV) depending if patient is able to take oral medication
- ) OXYGEN
On the other hand, in MILD to MOD exacerbation:
- Patient talks in phrases, prefers sitting to lying, not agitated
- RR is increased, pulse rate is 100-120 bpm
- Accessory muscles not used
- O2 sat 90-95%
- PEF >50% predicted or best
In mild-mod exacerbation of asthma, we start treatment by performing:
- SALBUTAMOL CHALLENGE TEST 4 mg/kg/dose
-Give 4 to 10 puffs of SABA by PMDI + spacer
-Repeat every 20 mins for 1 hr
-Monitor parameters every 15-20 mins to assess if the patient is improving or worsening
Parameters:
Vital signs
Wheezing
Crackles
Retractions
PEFR
If the patient is improving —> continue tx with SABA as need
If worsening —> assess need for transfer to an acute care facility
- Give PREDNISOLONE to address inflammatory component of asthma
Adults 1mg/kg max 50 mg
Children 1-2 mg/kg max 40 mg - If available, give Controlled Oxygen and target O2 saturation of
Adults 93-95%
Children 94-98%
While doing these management steps, we must simultaneously identify RISK FACTORS FOR ASTHMA-RELATED DEATH since this will affect our decision whether to discharge or admit the patient.
- History of near-fatal asthma requiring intubation & ventilation
- Hospitalization or Emergency care for asthma in the last 12 MONTHS
- Not currently using ICS, or poor adherence with ICS
- Currently using or recently stopped using OCS (this indicates severity of recent events)
- Over-use of SABA, more than 1 canister/month
- Lack of written asthma action plan
- HIstory of psychiatric disease of psychosocial problems
- Confirmed food allergy in a patient with asthma
If patient has 1 or more risk factor, even if symptoms are mild-moderate, there may be a need to ADMIT patient for further observation
