Respiratory Flashcards
Describe constituents and production of surfactants
Lipoprotein composed mainly of dipalmitoyl phosphatidylcholine.
Secreted by type 2 pneumocytes
Functions to increase compliance of alveoli
Fetuses begin production of surfactant between 24-28 weeks with maximum level at 36 weeks
Management approach for pulmonary hypertension
Specific therapeutic recommendations for Class I PAH
For all classes, treat the underlying cause.
Also:
- Pulmonary rehabilitation - improves QoL, VO2max
- Exercise training - improves endurance and aerobic capacity
- O2 if hypoxic
- Anticoagulation for IPAH, drug induced PAH, hereditary PAH and CTEPH (but not for CTD associated PAH as they bleed more)
For class I PAH, If positive vasoreactivity test on RHC, trial CCB (although large doses are often needed, eg nifedipine upto 240mg, diltiazem upto 900mg etc) Trial ERA, PDE5 inhibitors, GC stimulators, prostacyclin analogues
Role of tiotropium in COPD
Improves exacerbations, FEV1, symptom scores and QoL.
It however does NOT slow the rate of loss of lung function
Haldane effect
Increase in PO2 means CO2 binds less well to Hb
Name 5 strongest risk factors for VTE (OR >10)
- Fracture of lower limb
- Hip/knee replacement
- Heart related issues (admission for heart failure or AF or MI within last 3 months)
- Previous VTE
- Spinal cord injury
Action of Ivacaftor
CFTR potentiator, indicated in CF patients with G551D mutation in the CFTR gene.
Management of HACE?
- Descent
2. Dexamethasone
What is the risk of VTE recurrence after 12 months?
Around 10%
Recurrence risk is higher in unprovoked VTE and after multiple VTE episodes, continuing OCP, PE, proximal DVT, elevated d dimer
Which types of cancers are associated with highest risk of VTE? (name 5)
- Haematological Ca
- Lung
- GI
- Pancreatic
- Brain
Vareniciline
Nicotine receptor partial agonist.
Most effective - compared to placebo, NRT, bupropion.
Main SE is nausea in 30%, NOT dose dependent.
Also possible neuropsychiatric side effects such as suicidal ideation.
Classification of alpha 1 antitripsyn deficiency
Inherited in codominant fashion Alleles classified by their electrophoretic mobility - M for normal, S for slow, and Z for very slow normal = PiMM homozygous PiSS (50% normal A1AT levels) homozygous PiZZ (10% normal A1AT levels)
Patients who manifest disease have PiZZ.
Indications for home O2 therapy
PO2 <7.3 kPa
PO2 7.3-8 kPa and:
Secondary polycythaemia
Nocturnal hypoxemia
Cor pulmonale
Efficacy of triple therapy in COPD
OPTIMAL study in 2007 showed addition of seretide to tiotropium significantly improved disease specific QoL, frequency of all cause hospitalizations, lung function.
Efficacy of ICS in COPD - pros and cons
ICS + LABA reduced the rate of exacerbations RR 0.7, improved QoL and daily symptoms. One exacerbation was prevented for every 2-4 years of treatment.
However the caveat is:
- Increased oral candidiasis and skin bruising RR ~2
- Increased risk of pneumonia (OR 1.78 with fluticasone, less with budesonide OR 1.62)
Risk factors for pneumothorax recurrence?
- Male
- Tall
- Low body weight
- Persistent smoking
- Emphysematous lung blebs
What is the efficacy of PDE 5 inhibitors?
Includes sildenafil, tadalafil, vardenafil.
Improves haemodynamics, exercise capacity, WHO functional class and QoL, but actual mortality benefit is unknown.
What options of airway secretion management are available in CF?
- Inhaled Dornase alpha (DNase)
Improves FEV1 by 6%, reduces exacerbation - Inhaled hypertonic saline - no impact on FEV1 but reduces exacerbation frequency and absenteeism
- PEP therapy (positive expiratory pressure) - reduces exacerbation frequency.
Epidemiology of PE according to age, sex and race
- Increased risk with increasing age - risk doubles every decade after 40 years of age
- Females have lower recurrence rates of PE
- Males have higher incidence of PE
- Higher incidence in African Americans, but lower incidence in Asians and Pacific Islanders
5 Secondary causes of restless leg syndrome
- Iron deficiency
- Neurological disorders - spinal cord, peripheral nerve, vertebral disc
- Pregnancy
- Uraemia
- Drug induced -TCA, SSRI, dopamine antagonist, lithium
What is the role of inhaled antibiotics in bronchiectasis?
- CF associated
- Non - CF associated
In CF-associated bronchiectasis, inhaled antibiotics have been associated with reduced exacerbation, reduced airway inflammation and reduced bacterial load.
Current role is uncertain in non-CF bronchiectasis.
Indications for LTOT in COPD
- PaO2 <55 mmHg or
- PaO2 <60mmHg with pulmonary hypertension/RHF
Mortality benefit only with usage of more than 16 hours a day
Approximate carriage rate for CF gene
1:25
In CF, why do people undergo double lung transplant vs single lung transplant?
Contamination of the transplanted lung occur from the native lung as CF causes purulent disease.
Which is the only drug that has been proven ‘prospectively’ to have mortality benefit in class I PAH?
IV epoprostenol (prostacyclin) Improved symptoms, exercise tolerance and haemodynamics.
2 other drugs which have shown mortality benefit are Bosentan (against historical controls) and Macitentan (as a composite end point of mortality and morbidity)
6 causes of raised DLCO
- Asthma
- Polycythaemia
- Pulmonary haemorrhage
- Severe obesity
- Mild heart failure with increased pulmonary capillary blood volume
- Exercise prior to testing causing increased cardiac output
Causes of methaemoglobinaemia
Oxidization of Ferrous Fe2+ to Fe3+ (Ferric)
- Dapsone
- Topical anaesthetic agents such as lidocaine
- Inhaled NO
- Aniline dye
Methemoglobinemia is strongly suggested when there is clinical cyanosis in the presence of a calculated normal arterial pO2 (PaO2) as obtained by arterial blood gases. Arterial blood gas analysis is deceptive because the partial pressure of oxygen is normal in subjects with excessive levels of methemoglobin.
Indications for NIV in COPD exacerbation
- Hypercapnic respiratory failure
Consider instituting early when RR >30 and pH 7.35
Aim of reducing RR and increasing pH within an hour with repeat ABG to monitor.
What does a REDUCED TLC in the presence of ELEVATED RV/TLC ratio indicate?
Mixed obstructive/restrictive defect, or neuromuscular disease.
What is the purpose of BAL in diagnostic investigation of ILD?
To exclude chronic hypersensitivity pneumonitis
Retrospective data suggests that 8% with HRCT UIP pattern have BAL findings of an alternative diagnosis
Adverse prognostic factors for VTE on the basis of imaging findings?
- RV dysfunction on echo - 2x mortality
- RV thrombus - doubles 14 day mortality and 3 month mortality
- Coexistent DVT - increase in all cause mortality and PE specific mortality
Antibiotic rules for treatment of CF infections
One antibiotic for each organism isolated on culture
2 antibiotics for each gram negatives isolated if possible
Higher dose of antibiotics often required due to poor tissue penetration.
4 pathways targeted in PAH
- Endothelin pathway - prevents vasoconstriction
- NO pathway - NO produces vasodilation and inhibits proliferation
- Prostacyclin pathway - prostaglandins produce vasodilation and anti proliferation
- Soluble guanylate cyclase pathway
5 major causes of ILD
- Drug induced
- Granulomatous lung disease - sarcoidosis, hypersensitivity pneumonitis
- Connective tissue disease
- Others (pLAM, histiocytosis X)
- Idiopathic:
Idiopathic causes include: IPF, NSIP, COP, AIP, RBILD, DIP, LIP
5 treatment approach to bronchiectasis
- Screen and treat potentially treatable cause (eg: ABPA, CVID, MAC, AAT deficiency)
- Aid sputum clearance
- Pulmonary rehab - will reduce exacerbation and improve 6MWT
- Sputum culture - monitor future cultures for MAC, and attempt eradication of pseudomonas if first culture
- Macrolide therapy if frequent exacerbation - 3 ore more exacerbations in a year or 2x hospitalization in 12 months (modulation of inflammation)
What is the significance of mediastinal lymph node involvement in lung cancer?
If mediastinal lymph nodes are pathologically involved by tumour, then the patient has at least stage III disease and a combined modality therapy approach is most appropriate.
If mediastinal lymph nodes are negative by pathologic evaluation, then the patient has clinical stage I or II disease and resection of the primary tumour along with further mediastinal lymph node assessment at surgery is in order.
Bohr vs Haldane effect
Bohr effect - under the conditions of acidity, O2 binds less well to Hb facilitating unloading of O2
Haldane effect - increasing PO2 at the lungs lead to better unloading of CO2.
What is the role of PESI score?
Identifies very low risk to very high mortality risk at 30 days to determine who would be suitable for outpatient management.
If intermediate or high risk, requires further investigations such as echo to define RV function and to consider primary reperfusion.
Lancet study 2011 showed that PESI class 1/2 patients can be safely treated in outpatient setting without significance increase in VTE rates at 3 months or differences in bleeding rates.
Paraneoplastic syndromes associated with squamous cell carcinoma of the lung
- Parathyroid hormone-related protein (PTH-rp) secretion causing hypercalcaemia
- Clubbing
- Hypertrophic pulmonary osteoarthropathy (HPOA)
- Hyperthyroidism due to ectopic TSH secretion
Paraneoplastic phenomena associated with adenocarcinoma
Gynaecomastia
Mechanism of action of Riociguat?
Stimulates soluble guanylate cyclase and has 2 modes of action:
- Increases the sensitivity of sGC to endogenous NO and causes vasodilation
- Direct stimulation of NO receptor.
Improves 6MWT, WHO functional class, symptoms and PVR.
Has shown similar benefit in both class I PAH and CTEPH.
Mortality impact unknown.
Effect of long term macrolide therapy in bronchiectasis
Reduces exacerbation frequency
However increased macrolide resistance, no changes in FEV1, no changes in QoL, and benefit appears to be temporary.
Treatment of restless leg syndrome?
- Narcotics such as codeine
- Pregabalin - most useful, start at low dose
- Dopamine agonist such as sinemet or pramipexole
5 factors which affect TLCO measurements
- Anaemia decreases TLCO and vice versa
- COHb - decrease in TLCO due to decreased diffusiong radient and anaemia like effect caused by COHb
- Alveolar pCO2 - increased TLCO due to reduction in PAO2 and less competition for CO to bind to Hb
- Pulmonary capillary blood volume
- Body position - supine causes increased TLCO due to changes in blood flow distribution.
Why is pseudomonas colonization important in bronchiectasis?
Associated with more rapid FEV1 decline.
Upon being identified for the FIRST TIME, eradication with ciprofloxacin +/- nebulized colistin therapy or IV therapy can reduce exacerbation frequency.
At median 14 month follow up after eradication, 50% remain pseudomonas free.
Classification of pulmonary hypertension
- Pulmonary arterial hypertension (idiopathic, heritable PAH eg BMPR2 mutation, drugs or toxin induced, associated diseases such as CTD, HIV, schistosomiasis)
- PH due to left heart disease
- PH due to lung disease/hypoxia
- CTEPH
- PH due to multifactorial mechanisms - haematological, systemic disorders such as sarcoidosis
What does a normal TLC with increased RV on a lung volume measurement suggest?
- Gas trapping due to airflow limitation
- Neuromuscular disease (TLC often reduced as well)
If you have a normal TLC and increased FRC and RV, it means lungs are hyperinflated due to airflow limitation, and require breathing at higher resting lung volume to reduce airways resistance.
What is the role of ICS in bronchiectasis?
Not much evidence of benefit…
ICS may reduce sputum volume
However do not reduce exacerbation frequency or alter rate of FEV1 decline.
When should thrombophilia screen be undertaken?
- Positive family history (1 or more 1st degree relatives with VTE age <45)
If family history is -ve:
- Recurrent VTEs in patients <45 years
- Unusual sites of thrombosis or multiple sites (eg: portal, hepatic, mesenteric, cerebral veins)
- Warfarin induced skin necrosis
- Patients with arterial thrombosis
6 absolute contraindications in thrombolysis
- Haemorrhagic stroke or stroke of unknown origin at any time
- Ischaemic stroke within the last 6 months
- CNS neoplasm
- Recent major trauma/surgery/head injury in the preceding 3 weeks
- GI bleed within the last 1 month
- Known bleeding risk
What is the expected rate of FEV1 decline per year for CF?
2% per year
Endothelin 1 in PAH
Implicated in pathogenesis of PAH.
ET-A/ET-B receptors are present on smooth muscles - causes vasoconstriction and proliferation
ET-B receptors only are present on endothelium - causes NO release and vasodilation
Endothelin-1 levels are increased in plasma and lung in PAH and higher level correlates with disease activity and mortality.
Characteristics of UIP
- Lower zone and subpleural predominance
- Reticular pattern with honeycombing
- Traction bronchiectasis and architectural distortions
- Temporal heterogeneity on pathology with fibroblastic foci in ‘old’ collagen
Diagnostic criteria for ABPA?
Predisposing condition - asthma or CF (1 needs to be present)
Obligatory criteria - Positive skin prick test or Aspergillus specific IgE, PLUS elevated IgE needs to be present (both)
Other criteria: (at least 2)
Raised eosinophil >0.5 in steroid naïve individual
Radiology consistent with ABPA (CT normal in 20%)
Positive aspergillus precipitant or IgG to A fumigatus1