The Patient - Semester 2 Flashcards
What are the conducting airways and what are the components?
Anatomic dead space
Nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronichioles
What adaptation prevents the trachea and bronchi from collapsing?
Cartilage in the walls
What are the respiratory airways and what are the components?
Sites of gas exchange
Respiratory bronchioles, alveolar ducts, alveoli
What does one respiratory cycle consist of?
One inspiration and one expiration
Define ventilation
Bulk air entry caused by a drop in pressure as a result of increased lung volume
What are the pleural sacs and what are they connected to?
Fluid filled sacs surrounding the lungs
Inner membrane is connected to the lung and outer membrane is connected to the thoracic wall (spinal column, ribs and intercostal muscles) and diaphragm by connective tissue
How do the lungs expand?
Contraction of the diaphragm and intercostal muscles pulls on the pleural sacs which subsequently pulls on the elastic lung tissue, causing them to expand
What are the functions of the conducting airways?
- Low resistance airflow pathway
- Speech (larynx)
- Efficient O2/CO2 exchange - Warms and moistens air entering
- Infection defence by macrophages
- Mucus secretion - immune defence
How does mucus provide a barrier to infection in the conducting airways?
Mucus traps dust and microorganisms, cilia then wafts mucus towards pharynx where it can be swallowed to kill bacteria
How is movement of the mucus maintained?
Cl- moves out of epithelial cells through CFTR channel in apical membrane, watery fluid follows by osmosis
What is cystic fibrosis?
Defective CFTR results in inefficient Cl- movement and therefore a build up of mucus, increasing chances of infection as pathogens are not removed
What is a pneumothorax?
Breakage of pleural sac as a result of disease or injury - this results in air entering the chest cavity
The external air pressure causes the chest wall to expand and the lungs to collapse
How is injury to the lung contained to one side?
Lungs are isolated in pleural cavities so damage to one side prevents both lungs collapsing
What diseases can cause a pneumothorax?
Pneumonia and emphysema
What are the treatments for a minor, moderate and severe pneumothorax?
- Minor: Monitor by x ray and let body absorb air
- Moderate: Remove external air using a needle and tube
- Severe: Surgically repair lung or remove if damage is too severe
Define tidal volume, residual volume and vital capacity
- Tidal volume is the amount of air inhaled and exhaled during normal breathing
- Residual volume is the amount of air left in the lungs even after a forced exhalation
- Vital capacity = total volume - residual volume, can be worked out by measuring air expelled after taking a deep breath and and then a forced exhalation
What is the volume of an approximate inhalation/exhalation?
~500ml
What are the two ways of measuring ventilation and why are they important?
- Minute ventilation: Tidal vol. x Resp. Rate (ml/min)
- Alveolar Ventilation: (Tidal vol. - Dead Space) x Resp. Rate (ml/min)
Differences can highlight respiratory issues (e.g. shallow breathing which would result in inefficient gas exchange)
What is the volume of anatomical dead space?
~150ml
What are the lung function tests and what measurements are taken?
Spirometry, peak flow meter
FVC: Forced vital capacity
FEV1: Forced expiratory volume (in 1 sec) - Usually about 80% of FVC
What observations are made in Obstructive Lung Disease?
Give examples of conditions
- Normal FVC but FEV1 less than 80% due to resistance in airways
Asthma, COPD, CF
What observations are made in Restrictive Lung Disease?
Give examples of conditions
- Reduced FVC and FEV1 but FEV1 still ~80% due to poor expansion of the lungs
Fibrosing alveolitis, malignant infiltrations (e.g. tumours)
What is lung compliance?
How is it worked out?
Ease of expansion of the lungs - depends on relationship between transpulmonary pressure (difference in pleural and alveolar pressure) and lung volume
Cl = Change in vol/Change in pressure
Describe what would be seen in normal, low and high compliance
List conditions that may alter compliance
Normal: Increase in TP causes increase in lung volume
High: Small increase in TP causes large increase in lung volume (emphysema)
Low: Large increase in TP causes small increase in lung volume (fibrosis, pneumonia, oedema)
What are the two types of cells in the lungs?
Type 1: Gaseous exchange cells
Type 2: Cuboid cells, surfactant producers
What is the purpose of surfactant in the lungs?
Reduces lung surface tension to prevent alveoli collapsing
What is Newborn Respiratory Distress Syndrome?
Underdeveloped type 2 cells result in less surfactant production so lungs cannot stay open
What other conditions (generic) can cause low lung compliance?
Disorders affecting rib/spinal column articulation as the pleural sacs are connected to these
Why do ventilation and perfusion need to be matched?
Inequality results in reduced O2 entry to body
What is emphysema?
What causes it and how is it treated?
Degeneration of alveolar/bronchiole walls by proteases (produced by leukocytes), surrounding capillaries may also be affected
Usually caused by smoking and insufficient oxygen intake results in patient being put on O2
What is asthma? What causes it?
Inflammation of the conducting airways due to excess mucus and contraction of smooth muscle
Caused by environmental allergens
How are bronchodilators used to treat asthma?
- Beta receptors agonists: Mimic action of adrenaline by activating adenylate cyclase so ATP is converted to cAMP, cAMP caused relaxation of smooth muscle
- Phosphodiesterase inhibitors: These inhibit cAMP breakdown, maintaining relaxation of the airway smooth muscle
How are corticosteroids used to treat asthma?
- Corticosteroid binds to glucocorticoid receptor in epithelial cell cytoplasm
- Heat shock proteins dissociate from the receptor, allowing the receptor-drug complex to move to the nucleus where is binds to regions of DNA that transcribe for cytokines
- Reduction of cytokines results in reduced inflammation
What is the allergic component of asthma?
Overproduction of IgE - IgE binds to Fce region on mast cells, basophils and dendritic cells which causes release of histamine, cytokines, prostaglandins and leukotrienes
How are monoclonal antibodies used to treat asthma?
Give an example of one
- MAbs bind to Fc region on IgE to prevent binding to inflammatory cells
- Release of inflammatory markers inhibited
Omalizumab
What structures control breathing?
Pons and Medulla in the brainstem
What neurones are involved in breathing control and how do they have this effect?
Inspiratory, expiratory and mixed neurones from the pontine respiratory group
Impulses from neurones cause contraction of diaphragm and intercostal muscles
Where are central chemoreceptors found and what do they monitor?
- Brain stem medulla
- pH and pCO2 of cerebrospinal fluid
Where are peripheral chemoreceptors found and what do they monitor?
- Carotid and aortic bodies
- pH, pCO2 and pO2 of arterial blood
Why is high CO2 dangerous and how is it controlled?
High CO2 is toxic to respiratory neurones in the medulla
High levels detected by receptors which results in increased contraction of intercostal muscles and diaphragm
What causes reversible bronchospasm in asthma?
Release of cytokines by T-lymphocytes
What are the symptoms of asthma?
Shortness of breath, cough, dyspnoea, wheeze
What are the aims of asthma treatment?
Symptom control, prevent exacerbations and requirement of rescue pack, improve lung function, promote self care, minimise side effects
How can asthma be managed without medicines?
Avoid trigger Avoid cold air exposure Lifestyle changes (weight, smoking) Avoid use of NSAIDs and beta-blockers Buteyko breathing technique - slow, gentle breathing through nose to prevent drying airways
What routes can be used for administration of asthma drugs?
Oral or inhaled
What are the types of inhaled formulations?
Inhalers as relievers (SABAs), controllers (LABAs) and preventers (ICS)
Nebulisers in cases where coordination cannot be controlled
How are beta-2 agonists used in asthma treatment?
Relaxation of bronchial smooth muscle and enhanced mucus clearance by cilia
What are the side effects of b-2 agonists?
Tremor, nervous tension, headache, peripheral vasodilation, tachycardia, hyperkalaemia
What are the different types of corticosteroid treatment in asthma?
- Inhaled for prevention (beclometasone)
- 40-50mg orally for 5 days post-acute attack (prednisolone)
- IV in case of inability to take orally (hydrocortisone)
When is an ICS used as a preventer in asthma treatment?
- Exacerbation in the last 2 years
- Experiencing symptoms and use of b-agonist more than 3 times weekly
- Experiencing waking frequently
What are the side effects of an ICS?
Dysphonia, oral thrush, adrenal suppression, hypertension, osteoporosis, skin thinning, hyperglycaemia, moon face, acne
How are leukotriene antagonists used in asthma treatment?
- Given orally
- Prevention of bronchoconstriction, oedema and mucus production
Give two examples of leukotriene antagonists
Montelukast, Zafirlukast
What are the side effects of leukotriene antagonists?
Abdominal pain, headache, thirst, rash, sleep disturbance, effects on the CNS
How are methylxanthines used in asthma treatment?
Phosphodiesterase inhibitors - maintain bronchodilation (cAMP)
Prevent synthesis of leukotrienes
Give two examples of methylxanthines and their RoA
Theophylline - Oral
Aminophylline - Oral/IV
What are the issues with methylxanthines?
Narrow therapeutic index
CYP450 metabolism - drug interactions
What are the side effects of methylxanthines?
Nausea, diarrhoea, nervousness, headache, vomiting, insomnia, arrhythmia, hyperglycaemia, convulsions, death by overdose
What factors can reduce clearance of methylxanthines?
Congestive heart failure
Liver disease
Obesity
Enzyme inhibition
How are cromones used in asthma treatment? Give an example
Inhibit histamine release from mast cells
Nedocromil
What are the side effects of cromones?
Nausea and vomiting, bitter taste, indigestion (dyspepsia)
Give some examples of immunosuppressants used in asthmas treatment
Methotrexate
Ciclosporin
Gold
How are MAbs administered and how long is treatment?
Subcutaneously for 2-4 weeks
What are the steps for managing chronic asthma in adults?
- SABA prn
- Low dose ICS for prevention
- Add LABA if required
- If still uncontrolled, increase ICS dose
- Stop LABA and increase ICS further
- Trial LTA, SR theophylline or long-acting muscarinic antagonist (LAMA)
- Consider fourth drug
- Specialist referral
What factors affect Peak Expiratory Flow? What percentage of expected should it be?
Effort, age, height, sex
At least 80% of expected
What characterises acute severe asthma?
PEF <50%, dysphonia, RR >25, HR >110
What characterises acute life threatening asthma?
Severe PLUS silent chest, cyanosis, bradycardia, confusion, exhaustion, coma, inability to speak full sentences, PEF <33%
What drugs would be given if a patient is hospitalised for acute asthma?
- Nebulised b2-agonist, IV/oral steroid
- Possibly ipratropium nebuliser, IV MgSO4, IV aminophylline/salbutamol
What are the monitoring requirements in acute asthma?
PEF, O2 saturation, ABGs, HR, RR, theophylline level, K+ level, glucose level, hydration, WCC, CRP
What should be checked before discharging an asthma patient?
Inhaler technique
What is COPD?
Parenchymal damage (damage to functional parts of airways) Progressive airway obstruction Treatable but not curable
At what age is COPD a more likely diagnosis than asthma?
Above 35 years
What are the symptoms of COPD?
Chronic cough, mucus production, breathlessness
How is COPD diagnosed?
Spirometry, chest xray and FBC
What are the systematic effects of COPD?
Weight loss, skeletal muscle loss, osteoporosis, depression, increased risk of CVD
What increases the risk factor for COPD?
Smoking, age, gender (male) occupational hazards, previous lung impairment
Name a genetic risk factor for COPD
Alpha-1 antitrypsin deficiency
What are the aims of COPD treatment?
Improve day-to-day symptoms, prevent acute infective exacerbations, slow progression of disease, maintain nutritional intake, improve quality of life, smoking cessation
How do antimuscarinics reduce airway constriction?
Acetylcholine stimulates M3 receptors which cause bronchoconstriction, antimuscarinics prevent the action of acetylcholine
What are the side effects of antimuscarinics?
Dry mouth, blurred vision, urinary retention, constipation, hypotension
When are corticosteroids used in treatment of COPD?
If patient has FEV <50% and SABA has little or no effect
What should be avoided if patient is on oxygen therapy?
Smoking due to flammability
When is oxygen therapy used in COPD?
if FEV <35%
What oxygen concentration is used to prevent respiratory depression and why?
24-28% to prevent hypoxic drive (body responds to low O2 rather than high CO2 - oxygen treatment then takes away requirement to breath as body registers O2 levels as high)
How are infectious exacerbations prevented and how are they treated?
Administration of influenza and pneumococcal vaccines
Chest infections are treated with antibiotics
What are mucolytics and when are they used in COPD treatment?
Reduce viscosity of mucus so it is easier to expel from the airways
Used when patient has a chronic productive cough
How are LAMAs/LABAs used in COPD treatment?
Unmanaged COPD, if FEV <80% give combination inhaler of LABA/ICS
If still unmanaged give LAMA + combination inhaler
What lifestyle changes can be made to improve COPD symptoms?
Smoking cessation, exercise, nutrition management
How often is COPD reviewed and what parameters and checked?
Annually
FEV, dyspnoea, BMI, depression, inhaler technique and medication review
What is the danger of using steroids in COPD treatment?
Steroid increase susceptibility to infection so infective exacerbations (chest infections) are more likely
What antibiotics are used to treat a chest infection?
Amoxicillin 500mg TDS, tetracycline, doxycycline 200mg STAT then 100mg OD
May use broad spectrum cephalosporin or macrolide
What is cor pulmonale?
Right side heart death due to damage to the pulmonary circuit as a result of hypertension
What is polycythaemia?
RBC and haematocrit level rises due to hypoxia, blood viscosity increases
What are the functions of the tissues and organs in the GIT?
Specialised for digestion and absorption
Define alimentary
Relating to nutrition
What are the components of the GIT?
Mouth, pharynx, oesophagus, stomach, small intestine (duodenum, jejunum, ileum), large intestine (colon,), rectum, anus
What are the accessory structures to the GIT and what are their functions?
Salivary glands (sublingual, submandibular and parotid)
Secretion of amylase and lipase, mucin production (glycoprotein that provides lubrication for swallowing)
What does the Mumps virus affect and what are the symptoms?
Affects parotid glands
Swelling to side of face and neck
Describe the mechanism of swallowing
Food bolus sensed by tactile receptors in the back of the throat, signal sent to medulla oblongata which then sends impulses to throat musculature, causing coordination of swallowing
What 6 nerve groups are involved in coordination of swallowing?
Trigeminal, facial, glossopharyngeal, vagus, spinal accessory and hypoglossal
What patients may develop dysphagia?
Stroke patients due to nerve damage
Describe the journey of a food bolus
Mouth -> Oesophagus -> Stomach (past oesophageal hiatus)
What is a hiatus hernia?
Stomach pushes through diaphragm resulting in acid reflux
What is Barrett’s Oesophagus?
Squamous epithelial cells damaged by acid reflux and then replaced with abnormal columnar cells (pre-cancerous)
Patients at higher risk of developing adenocarcinoma
What adaptation prevents stomach acid from entering the oesophagus?
Lower oesophageal sphincter seals stomach
What are the four types of gastric cells?
Mucus cells, G-Cells, Chief Cells, Parietal Cells
What are the functions of G-Cells?
Gastrin secretion, gastrin binds to parietal cells causing HCl release
What are the functions of Chief Cells?
Secrete pepsinogen (pepsin in inactive form) Secrete gastric lipase
What are the functions of Parietal Cells?
HCl release (p. cell pumps H+ into stomach lumen):
Food receptors send impulses to stomach causing release of acetylcholine
Gastrin binds to parietal cells causing HCl release
Stomach distension causes release of histamine which causes release of HCl
How are H2 receptor antagonists used to treat acid reflux? Give two examples
Histamine effects reduced or abolished by blocking receptor
Cimetidine and Ranitidine
How are PPIs used to treat acid reflux?
Inhibition of H+/K+ ATPase pump, preventing H+ entering stomach so no formation of HCl
Why are enteric coatings used in drug formulations? Give two examples that may need enteric coatings
Some drugs may undergo degradation by HCl in the stomach, enteric coating protects active ingredient
Penicillin G and erythromycin
What structures are best absorbed in the BIT and why?
Lipid-soluble, weakly acidic drugs because they remain unionised and can cross the lipid membrane
What is the main site of absorption in the GIT?
Small intestine
What are the protective adaptations of the stomach?
- Pepsin secreted as inactive pepsinogen to prevent breakdown of stomach proteins
- Mucus layer produced by foveolar cells protects stomach epithelium - neutralises stomach acid and protects from protease digestion
- Epithelial cells connected by tight junctions prevents exposure of epithelium to acid/pepsin
- Cells are replaced every 2-3 days
How gastric/duodenal ulcers formed?
Breakdown of protective adaptations leads to damage of the stomach epithelium
If damage extends deep enough it can damage blood vessels and cause a haemorrhage
If damage erodes GIT wall (perforated ulcer) chyme may enter peritoneal cavity
What is peritonitis?
Inflammation of the peritoneum due to contact with chyme, can lead to sepsis
What is the relationship between Helicobacter pylori and gastric ulcers?
Infections are a common cause of ulcers, eradication of H. pylori dramatically reduced incidence of ulcers
What are the treatments and doses of H.pylori infections?
Two antibiotics and PPI:
Clarithromycin (500mg BD) + Amoxicillin (1g BD) + Omeprazole/Esomeprazole (20mg BD)
Clarithromycin (250mg BD) + Metronidazole (400mg BD) + Omeprazole/Esomeprazole (20mg BD)
What is peristalsis?
Coordinated contraction of intestine to push a food bolus along the lumen
Circular muscles contract to prevent the backwards movement of a food bolus whereas longitudinal muscles contract to push the food bolus along