Periop respiratory Flashcards
What are the goals of COPD assessment?
To determine:
- Severity of airflow limitation
- Severity of symptoms
- Risk of future events (exacerbation, hospital admission, death)
What is the GOLD crtieria for COPD relating to FEV1?
Defined as FEV1/FVC <0.7
GOLD 1: Mild = FEV1 > 80% (needs symptoms) and FEV1/FVC < 0.7
GOLD 2: Moderate = FEV1 50-80%
GOLD 3: Severe = FEV1 30-50%
GOLD 4: Very severe = FEV1 <30%
What are the treatments for COPD?
- Smoking cessation
- Pharmacological treatment: Bronchodilators: combination LABA + LAMA (long acting muscarinic antagonists), + short acting SABA/SAMA + inhaled corticosteroids
- vaccinations
- Pulm rehab
- Long term Oxygen
- Surgical or endobronchial interventions
- Lung transplant
What is the pathophysiology of COPD?
- Inflammatory condition that leads to poorly reversible narrowing of the airways, remodelling of smooth muscle and increased number of goblet and mucus secreting glands
- Characterised by expiratory airflow obstruction due to a combination of small airways inflammation and parenchymal destruction
What are the anaesthetic considerations for COPD?
- Pre op:
S - functional status and recent control
C - IHD, smoking
O - nutritional support (low BMI and albumin are strong predictors of post op complciations)
M- consider stress dosing if >20mg/day for 3 weeks - Intra op issues:
- Laryngospasm
- Bronchospasm
- CVS instability
- Hypoxia
- Barotrauma
- aim for local/sedation/regional
- monitor for gas trapping
- lung protective strategies include low RR, longer expiratory times
- Optomise patient prior to extubation (full reversed, warm, oxygenated, normal PaCO2 for baseline, bronchodilated)
- consider extubation onto NIV
Post op:
- Analgesia
- Close monitoring
- Suction/physiotherapy/saline nebs for sputum plugging
What is asthma?
- reversible airflow obstruction due to airway hyper-responsiveness
- Bronchial wall inflammation results in mucus hypersecretion, epithelial damage and constriction of airways
- well controlled asthma -> limited issues
- poorly controlled asthma -> increased risk of periop pulm complications (bronchospasm, laryngospasm, sputum plugging, atelectasis, infection, resp failure)
What are preop considerations for a patient with asthma?
- level of asthma control
- triggers
- last attack
- med hx
What are the levels of severity for asthma?
- FEV1 (% predicted)
Mild: 65-80
Moderate: 50 -64
Marked: 35 - 49
Severe : <35
What are the anaesthetic implications of asthma?
- Pre op should be asymptomatic and free of wheeze
- Avoid airway instrumentation
- Blunt airway relfexes (deep anaesthesia, topical LA, opioids)
- Bronchodilation, avoid histamine release eg morphine
- Permissive hypercapnia (increased exp time, decrease RR, adequate tidal volumes, minimise PEEP)
- Monitor intrinsic PEEP, presence of dynamic hyperinflation
- Post op monitor for bronchospasm or resp failure
What is bronchiectasis?
- chronic localised, irreversible dilation of parts of bronchial tree
- These are inflamed, easily collapsible that lead to airflow obstruction and implaired clearance of secretions
What are common causes of bronchiectasis?
Acquired:
-necrotising bacterial infections
-chronic partial obstruction e.g. from tumour or foreign bodies
Congenital:
- cystic fibrosis
- ciliary dysmotility – e.g. Kartagener’s syndrome
What are clinical features of bronchiectasis?
- Haemoptysis
- Recurrent LRTI
- Chronic cough with purulent sputum
- positional cough
what are anaesthetic goals of anaesthetics with bronchiectasis?
- elcucidate cause and severity eg may be CF or systemic disease
- Optomise per op resp function
eg delay surgery ? if active sx
eg Pre op ABx
eg Pre op chest physio
eg Regional vs general
eg increase steroid dose - protect healthy lung from soiling of other
eg induce slightly head up
consider DL ETT - Manage risk of haemorrhage
due to chronic inflam
eg large Venous access
cross match
Post op:
- regular physiotherapy
- monitor sats
- continue ABx post op
What is cystic fibrosis?
- autosomal recessive multisystem disorder
- Due to issues with gene for Cl- channel transport
What are the clinical manifestations of cystic fibrosis?
- Resp: thick secretions, frequent URTI, nasal polyps
- CVS: right heart failure
- GIT: portal hypertension, focal biliary cirrhosis, pancreatic insufficiency, bowel obstructions
- Endo: CF related diabetes, osteoperosis
- Impaired sweating
What are anaesthetic considerations of patients with CF?
Pre op:
- Severity and stability etc
- Recent PFTs
Intra op:
- Regional if possible, avoid airway
- Avoid nasal intubations
- consider art line for regular ABGs
Post op:
- Consider HDU
- early extubation
- early chest physio
What are the types of sleep disordered breathing?
- OSA
- Hypercapnic central sleep apnoea (eg Obesity hypoventilation syndrome)
- Non-hypercapnic central sleep apnoea (common in heart failure)
What is the diagnosis of OSA?
- can be assisted with STOP BANG
- Gold standard is overnight polysomnography
- AHI > 5 = mild
- AHI > 15 = moderate
- AHI > 30 = severe
AHI is the sum of apnoea and hypopnoea episodes divided by sleep duration ( in hours)
Apneoea = ventilation pause >10 secs
Hypopoea = 50% reduction in airflow with spo2 desat >3%
- Other way is oxyden desaturation index, >5 episodes of desat >4% per hour
What are the physiological effects of OSA?
- Increased mortality
- CVS: HTN, arrhythmia, AMI, CCF, stroke
- CNS: tiredness, impaired cognitive function, depression
ENDO: impaired glucose tolerance, dyslipidaemia, increased cortisol, PCOS
What are anaesthetic issues with patients with OSA?
- Preop optomisation: - if strong suspicion should have formal sleep study prior to major surgery
- If signs of CCF or PaCO2 > 48 then should delay surgery until optomised
- Intraoperative:
- avoid premeds and opioid spare (multimodal)
- Plan for difficult BMV + intubation
- Consider regional
- Adequate pre-oxygenation and PEEP
- Extubate fully reversed, awake, sitting up
- Post op:
- Have CPAP available
- Close monitoring as required
- consider overnight oximetry
What is restrictive lung disease?
- conditions where lung expansion is reduced
- All lung volumes are decreased, decreased lung compliance but expiratory flow rates are preserved
What are causes of restrictive lung disease?
- Acute intrinsic eg Pulmonary oedema and its various causes, aspiration
- Chronic intrinsic eg interstitial lung disease such as sarcoidosis, drug induced pulmonary fibrosis
- Chronic extrinsic: eg diseases of chest wall, pleura and mediastinum eg skeletal deformities, pleural effusion, pneumothorax, neuromuscular disorders
What are anaesthetic implications of restrictive lung disease?
- worsened FRC when lying flat -> quick desat
- Reduce peak pressure if possible (lung protective ventilation, low TV and high RR)
What are the 3 invesigations for pre thoracotomy resp assessment?
- Respiratory mechanics, FEV1 > 40%
- Cardiopulm reserve VO2 max > 15ml/kg/min
- Lung parenchymal function, DLCO >40%
