13. Respiratory Flashcards
What is Asthma?
Asthma = a chronic respiratory disorder characterised by variable airway obstruction and hyper-responsiveness to stimuli.
What is the narrowing of the airways due to in Asthma ?
Narrowing of the airways due to:
* – Bronchial smooth muscle spasm.
* – Swelling of bronchial mucosa.
* – Excess viscous mucus secretion.
What are the hallmark symptoms of asthma?
Hallmark symptoms: Wheeze, intermittent shortness of breath, chest tightness and dry cough.
Describe an asthma attack?
- Initially shortness of breath, coughing, or chest tightness.
- May be itching of the chest or neck, especially in children.
- Wheezing when breathing out (expiratory wheeze).
- May start slowly with gradually worsening symptoms.
- Can last minutes, hours, or even days.
- Dry cough at night or while exercising (may be the only symptoms).
- Anxiety and sweating are common during an acute attack.
What is the pathophysiology of asthma?
1* Usually mediated by immunoglobulin E (IgE) and precipitated by an allergic response to an allergen (e.g., pollen, animal dander).
2* Leads to the release of inflammatory mediators such as histamine leukotrienes, and prostaglandins, which cause bronchospasm, triggering an asthma attack.
3* If untreated, eosinophils, T-helper cells and mast cells migrate into the airways.
4* Mucus production by goblet cells is ↑ plugging the airway and, together with increased airway tone and hyper-responsiveness, causes the airway to narrow, further exacerbating symptoms.
5* Airway remodelling — chronic inflammation causes bronchial smooth muscle hypertrophy, formation of new vessels and interstitial collagen deposition. Results in persistent airflow obstruction, similar to COPD.
6* Lipoxygenase products: Most potent chemical mediators in asthma. Leukotrienes are 1000 times more potent stimulators of bronchial constriction than histamine.
7* Asthmatics have an imbalance in arachidonic acid metabolism, leading to relative increases in lipoxygenase products.
8* COX is downregulated in favour of LOX leading to ↑ leukotrienes.
Causes and risk factors of asthma x15
1* Immune tolerance: Th1 / Th2 balance is important as excessive Th2 response encourages IgE release, ↑ inflammatory mediators.
2* Heightened Th2 immune response during pregnancy predisposes infant to allergic disease.
3* In asthma, inadequate antigen exposure causes abnormal responses to innocuous stimuli.
4* Development of oral tolerance ↓ Th2 response as the GI immune system gradually differentiates between antigens.
5* ‘Hygiene Hypothesis’ (see immune lecture). Pathogen exposure supports neonatal immune development by increasing Th1.
6. Antibiotics
7. not breastfeeding
8. obesity
9. Female sex hormones fluctuations
10* Preservatives — benzoates, sulphur dioxide, sulphites in food / drink may aggravate asthma in children.
11* Molybdenum deficiency — can contribute to sulphite sensitivity as it is a co-factor for sulphite oxidase (oxidises sulphite to sulphate, enabling safe urinary excretion).
12* Food colourings — azo dyes (esp. tartrazine) may trigger attack.
13* Low vitamin D and magnesium status (see later slides).
14* Drugs — aspirin, NSAIDs, β-adrenergic & opiates==>bronchospasm.
15* Aspirin and NSAID sensitivity in asthma cannot be predicted, thus they are best avoided.
Causes and risk factors of asthma - antibiotics
Antibiotics: Pre- or post-natal exposure to antibiotics can ↑ the risk and severity of asthma in children.
* First year of life critical in development of the gut microbiome — gut dysbiosis linked to early disruption of the immune system and the development of chronic atopic and inflammatory diseases.
* Compromised gut microbiome leads to antigen stimulation of antibody pathway causing heightened Th2 response with increased antigen sensitivity and abnormal responses.
* The presence of pathogenic bacteria and fungi (e.g., Candida albicans) in the gut and lungs of infants and children has been linked with development of allergic sensitisation and asthma.
Causes and risk factors of asthma - not breastfeeding
Not breastfeeding: Breastfeeding is protective via several mechanisms including immune development and gut microbiome.
* Early weaning (< 6 months): Longer breastfeeding shown to result in ↓ risk of wheeze and to have a protective effect until school age.
* Ideally, exclusively breastfeed for 6–9 months; early weaning, and feeding infant formula, ↑ risk of food allergy, including asthma.
Causes and risk factors of asthma - obesity
Obesity: Increases risk, symptoms and frequency / severity of attacks.
Factors implicated in obese asthma include:
* Lung function: Changes in mechanical properties of lungs and chest wall significantly ↓ ERV and FRC.
* Diets that promote obesity: (↑ saturated fat and sugar, ↑ omega 6:3, low fibre and antioxidants) increase asthma risk.
* Microbiome changes: Obesity is linked with low Bacteroidetes bacteria (major producer of SCFAs). Alterations in circulating SCFAs increase allergic airway disease.
* Systemic inflammation: ↑ cytokines released from adipose tissue contribute to airway hyper-responsiveness and remodelling.
ERV = expiratory reserve volume
FRC = functional residual capacity
Causes and risk factors of asthma - Female sex hormone fluctuations:
Female sex hormone fluctuations:
* Raised oestrogen (oestrogen favours Th2) — see women’s health lecture.
* HRT — linked with ↑ risk of severe exacerbations in asthmatic women versus non-use, with greater risk seen in those with previous rather than current use.
* Perimenstrual asthma — a cyclical worsening of asthma during the luteal phase and / or first few days of menstruation.
* Relates to hormone fluctuations, particularly the impact of oestrogen changes at ovulation and prior to menstruation.
Hormonal balancing may be central to asthma management.
How is asthma diagnosed?
Diagnosis: Medical history, physical examination, lung function tests (spirometry / peak expiratory flow). No gold standard test.
What are the two classifications for asthma?
Extrinsic (allergic / atopic) asthma (60–90% of cases):
– Involves an IgE mediated response.
– Common triggers include pollen, mould, dust mites, pet dander.
Intrinsic (non-allergic) asthma (10–40% of cases):
– More common in females, typically develops later in life.
– Bronchial reaction, IgE can sometimes be involved.
– Possible triggers cold temperatures, humidity, stress, exercise, pollution, irritants in air such as smoke, and respiratory infections.
Asthma natural approach - what dietary/lifestyle evaluations to do to help identify contributing factors: ? x5
- Dietary / lifestyle evaluation: Diet diary, thorough case history, elimination diet (see GI lecture), identification of triggers.
- IgG / IgE food profile: e.g., York Test IgG foods and IgE foods test. Assess potential food allergy or intolerances.
- IgG / IgE inhalant allergy profile: e.g., Genova’s inhalants / IgE moulds test. Assess for chemical or environmental irritants.
- Food / chemical intolerance test: e.g., Genova’s toxic element clearance profile, elemental analysis. Assess specific food additives, colourings, pharmaco-active agents, environmental chemicals
- GI profile or digestive analysis: e.g., Genova’s NutrEval. To ensure optimal digestion, microflora colonisation and immune health.
Natural approach to asthma what to include? x5
1* Allergies and sensitivities: Reduce pre-disposition in child; consider nutritional status of parents and pre-conception toxin exposure.
2* Follow CNM Naturopathic Diet — see previous lectures.
3* Eat only fresh, natural, unprocessed organic food pre-conception / pregnancy. Eliminate / reduce common allergenic foods. Eat fish / purified fish oil supplement (during pregnancy / lactation).
4* Breastfeeding reduces incidence and severity of asthma. 1st year of child’s life critical — minimise chemical exposure as immature liver is unable to detoxify many compounds.
5* Ensure good sleep; minimise stress (see previous lectures)
Natural approach to asthma what to avoid? x12
1* Dietary exclusions — most common foods associated with asthma are cows’ milk, eggs, chocolate, rice, soy, corn, citrus fruit, apple.
2* Salicylate sensitivity — may cause delayed intolerance reaction. Assess client tolerance.
3* Avoid dietary sulphites — alcohol, dried fruits, bagged / prepared salads.
4* Avoid nitrates: Cured meat ↑ symptoms.
5* MSG and its derivatives.
6* Avoid very cold drinks (can trigger bronchial spasm).
7* Care with gas-producing foods (↑ pressure on diaphragm).
8* Reduce intake — sugar, dairy, processed foods, wheat, additives, preservatives, colourings.
9* Reduce red meat — arachidonic acid link to ↑ series 2 prostaglandins and leukotrienes (transient airway hyper-responsiveness).
10* Dehydration — may exacerbate exercise-induced asthma.
11* Excess salt — potentially increases bronchial reactivity.
12* Stress and anxiety contribute to asthma exacerbations. Occurs through various mechanisms e.g., oxidative stress pathways, glucocorticoid resistance, nerve-mast cell interaction.
Natural approach to asthma what to include to avoid oxidative stress? x13
Dietary inclusions: To reduce oxidative stress.
1* Antioxidants: Include vitamins A, C, E, carotenes, co-factors — zinc, selenium, copper, and flavonoids (particularly quercetin). These:
2* – Inhibit leukotriene formation and histamine release.
3* – Increase epithelial lining integrity.
4* – Protect lung against free radicals and oxidising agents that may stimulate bronchial constriction and ↑ hyper-responsiveness.
5* Increase selenium (a co-factor of GPO) — often low in asthmatics.
6* Increase vitamin E — potent antioxidant, improves lung function, optimises Th1 and suppresses Th2, ↓ IgE and atopy.
7* Flavonoids — such as quercetin inhibit histamine release from mast cells and basophils when stimulated by antigens. Quercetin decreases airway inflammation and hyper-responsiveness. Increase in diet and / or supplement up to 3 g / day (adult dose) before meals.
8* Support SIgA levels — probiotics incl. S. boulardii, zinc, A, D, colostrum for immune tolerance and reduced food reactions.
9* Optimise omega-6:3 ratio — an inflammatory omega 6:3 profile causes ↑ prostaglandin E2 (PGE2)IgE = atopy and inflammation.
10* Ensure optimal digestive function (see digestion lecture). Low HCl and protein maldigestion is linked to asthma in children.
11* Dietary fibre — associated with improvements in lung function — anti-oxidant and anti-inflammatory effects (25 g / d women; 35 g / d man).
12* Studies show an inverse association between fibre intake and pro-inflammatory interleukin-6 (IL-6), tumour necrosis factor-α receptor-2, and C-reactive protein.
13* Fibre is metabolised by gut bacteria into SCFAs which positively influence immune and metabolic responses.
Nutrients for Asthma x7
- Vitamin C: 2–3 g / day in divided doses
- Vitamin D: Optimise levels
- Magnesium: 200‒400 mg / day
- Zinc: 15‒30 mg / day
- Probiotics: L. rhamnosus GG and GR-1 Dosage as per label
- Fish oils: 1 g of actual EPA or higher as required.
- Coenzyme Q10: 150 mg / day
VitC for asthma - functions and dose
- Antioxidant, anti-histamine, stimulates neutrophils, increases lymphocyte and interferon production.
- ↓ release of arachidonic acid which impedes prostaglandin E2 (PGE2) synthesis = ↓ inflammation and bronchoconstriction.
- ↓ bronchial spasm (1 g daily), prevents exercise-induced asthma (500 mg).
Vitamin C:
2–3 g / day in divided doses
VitD for asthma - functions and dose
- Modulates genes for asthma / allergy. Maternal levels linked to allergy — higher levels protective against asthmatic wheezing in young children.
- Inhibits eosinophils (involved in pathogenesis of asthma).
Vitamin D:
Optimise levels
Magnesium for asthma - functions and dose
- Improves lung function, reduces bronchial reactivity.
- Antagonises movement of calcium across membranes, ↓ calcium uptake in bronchial smooth muscles leads to relaxation / dilation bronchial airways.
- Used as bronchodilator in acute asthma attacks. Linked with↓ bronchial reactivity
Magnesium:
200‒400 mg / day
Zinc for asthma - functions and dose
- Improves cell-mediated immunity — increases production of T-lymphocytes, regulates function of white blood cells.
- Deficiency may shift Th1 / Th2 response, favouring Th2 response characteristic of asthma.
Zinc:
15‒30 mg / day
Probiotics for asthma - functions and dose
- Balance Th1 / Th2 immunity — ↑Th1 cytokines profile (IL-12, IFN-γ, and TGF-β), ↓Th2 cytokine profile (IL-4, IL-5, IL-10, and IL-13).
- ↓ eosinophil and lymphocytes infiltration to the respiratory tract, ↓ IgE, IgG1, IgG2a production.
- ↑ butyrate / IgA production, alleviate symptoms, ↑ quality life.
Probiotics:
L. rhamnosus GG and GR-1 Dosage as per label
