Thoracics Flashcards
What are the indications for one-lung ventilation?
Surgically - to facilitate access:
- Oesophageal surgery
- Cardiothoracic surgery
- Spinal surgery in lateral position
Therapeutically
- Prevent contents of one lung (blood/pus/secretions) entering another
- Prevent ventilation of lung with significant air leak e.g. trauma/bullae rupture
3 methods of one-lung ventilation
- Double lumen ETT
- Standard ETT + bronchial blocker
- Standard ETT inserted endobronchially
Advantages and disadvantages of DLT?
Advan
- Most definitive.
- Tracheal outlet allows option of ventilating either lung and accessing non dependent lung for suction, bronchoscopy, application of CPAP
Disadvantages
- Large and bulky. Insertion may be traumatic or difficult
- Must be changed to standard prior to transfer if patient remains intubated
Advantages and disadvantages of bronchial blocker
Placed via bronchoscope into non-ventilated lung
Advan
- Can be inserted via existing ETT or tracheostomy - good for difficult airways
Disadvantages
- More likely to migrate on repositioning
- Doesn’t allow suction or application of CPAP
Advantages and disadvantages of standard ETT advanced endobronchially
Advan
- Simplest technique, no specialist equipment
- Useful in emergencies
Disadvantages
- No access to non-dependant lung for suction/CPAP/bronchoscopy
- Collapse unpredictable
Talk me through insertion of a DLT
Preparation:
- Airway assessment to anticipate difficulty
- Full team brief
- Appropriate size (Male 39-41 fr, Female 37-39 fr)
Induction:
- Careful induction, full AAGBI monitoring, fibreoptic scope set up
- Use stylet, tip positioned anteriorly
- Rotate anticlockwise Left DLT, clockwise Right DLT, 90deg
- Advance until resistance around 26-29cm
Confirmation:
- Auscultation vs fibreoptic
- Auscultation
- Inflate tracheal cuff confirm capnography and bilateral lung ventilation
- Clamp tracheal circuit (+ open port), inflate bronchial cuff 1-3ml and check unilateral ventilation
- Release clamp and confirm bilateral
Or fibreoptic
Confirmation DLETT placement
Strategies if you encounter hypoxaemia with DLT?
Start with usual spiel about recognising and announcing issue to team members
Increase fiO2 to 1.0
Check fgf, quick check of patient/equipment
Reconfirm position with fibreoptic scope
Ensure adequate haemodynamics (fluid/vasopressors)
Recruit ventilated lung
Increase PEEP ventilated lung
Application of CPAP and O2 to NON-ventilated lung
Intermittent reinflation NON-ventilated lung
Severe desat - resume bilateral ventilation (inform surgeons!)
In pneumonectomy - clamping pulmonary arteries
How might PEEP worsen hypoxaemia in recruitment manouvre to dependent lung
Balance between increasing pulmonary shunt due to increased resistance to blood flow
AND
Advantages of peep - prevention of de-recruitment and atelectasis
Complications of lateral positioning?
Airway
- Difficult to access
- May become dislodged
Ventilation
- Ventilation/perfusion better in dependent position
- If bad lung was down then could lead to V/Q mismatch
Pressure injuries
- Radial nerve / common peroneal nerve / saphenous nerve
- Miticulous positioning
- Avoid overstretching of neck and pressure areas to eyes
- Impeding IJV drainage may lead to poor lymphatic drainage of tongue and maccroglosia
What 3 areas do BTS guidelines recommend assessing prior to lung resections?
- Pos-op cardiac risk
Cardiac risk tools for non cardiac risk surgery - Revised Cardiac Risk Index
Cardiac optimisation
Echocardiogram
Other tests e.g. right heart cath prior to pneumonectomy if indicated
- Perioperative death
Thoracoscore, logistic model based on 9 variables
- Age
- Sex
- ASA
- Performance status
- Dyspnoea score
- Surgical urgency
- Surgical extent
- Malignancy
- Co-morbidity score - Post-operative dyspnoea
- Lung volumes / spirometry to assess mechanics
- DLCO / transfer factor to assess parenchyma
How are patients risk stratified for surgery and surgery decision made?
Made by MDT combining history, examination, investigations
Patients can be risk stratified using post-operative dyspnea prediction
PPO = predicted post-op value
= pre-op value x (19- no. of segments resected / 19)
Compare to normal predicted
If ppoFEV1 and ppoDLCT >40% consider for surgery , > 50% if pneumonectomy
High risk e.g. <30% consider for non-surgical
Counsel borderlines patients for long term dyspnoea / O2 therapy
Other modalities for making a decision for thoracic surgery
- CPET - NICE recommends >15mlO2/kg/min as threshold
- Shuttle walk test, walk between 2x 10m points with increasing pace, <400m completed poor prognostic sign
Causes of bronchopleural fistula?
Iatrogenic
- Surgical (lobectomy, pneumonectomy)
- Line insertion
- Chest drain insertion
- Lung biopsy
- Barotrauma - mechanical ventilation
Infective
- Pneumonia, TB
Other
- Trauma
- Chemo/radiothrapy
Risk factors for bronchopleural fistula?
Right-sided pneumonectomy (exposed bronchial stump)
Pleural/pulmonary infection
Pre-op steroids
Pre-op radiotherapy
Diabetes
Malignancy
Post-op mechanical ventilation
Ventilatory strategy for intubated patient with bronchopleural fistula?
Goal is to maintain adequate oxygenation/ventilation whilst minimising air flow through fistula so it heals
Spont breathing/PSV when possible
Low tidal volumes, permissive high PaCO2
Low PEEP, permissive low sats
Short i. time
Indications for rigid bronchoscopy
May be diagnostic or therapeutic
Diagnostic
= inspection of tracheobronchial lesions
= biopsy of lesions
Therapeutic
= application of stent to airway
= removal of foreign body
What are the anaesthetic considerations for rigid bronchoscopy?
Airway/breathing:
- Risk of airway obstruction
- Shared airway, need good communication
- Plan for maintanance of ventilation and gas exchange
- Induction of anaesthesia with periods of unprotected airway - assess reflux risk
Cardiovascular:
- Stimulating procedure with potential cardiovascular instability
Maintanance of anaesthesia
- TIVA technique
Surgical stimulation
- Coughing ++
- Topicalisation and short acting agents
Bleeding
- Strategies include turning biopsy side down, monitoring for obstruction post procedure
Ventilation options during rigid bronchoscopy
Positive pressure ventilation
- Rigid bronchoscope with jet ventilator
- Low frequency, delivers O2 at 4 atm, entrains air
- Expiration is passive
- No control of FiO2, hypercapnoea may result, risk of barotrauma
Apnoeic oxygentation
- Up to 70L/min humidified
- Rise in PaCO2 if long procedure but less than apnoea without HFNO
- May not be possible in obese patients or airway abnormalities
Spont vent
- Open breathing system
- TIVA
- Difficult if need high dose opioid or muscle paralysis
Anaesthetic considerations airway stenting procedure?
In addition to usual anaesthetic assessment focus on
Hx/exam/Ix
Hx:
- Co-morbidities. Cancer dx. Smoking. Resp/cardiovascular disease
Exam:
- Airway assessment, nutritional status, cardiovascular, resp
Ix:
- CXR
- CT chest/neck
- Pulmonary function - flow-volume loop spirometry, fixed or dynamic obstruction
Optimisation of comorbidities whilst balanaced against procedure urgency
Anaesthetic “how to” - airway stent surgery
PRIMADE TIME
General anaesthesia required for placement of stents
Arterial line prior to induction
TIVA for maintanence
Choice of airway depends on patient and surgical options (e.g. rigid vs. flexi bronchoscope)
FLexi
- Maintain by volatile or TIVA
- Can be LMA or ETT or tubeless (e.g. THRIVE)
- ETT can cause coughing and dislodge stent
Rigig
- Maintanence with TIVA
- Volatile can be delivered by side port but no ET monitoring
- Oxygenation with JET
How does gas exchange occur with jet ventilation
- Bulk convection
- Negative pressure arises as greater volume of O2 absorbed than CO2 produced - Pendelluft
- Movement of gas between lung units with different time constants - Convective streaming
- Fast flowing gas found at centre of airways, slow flowing at periphery
Three specific risks in thoracic surgery
- Subglottic obstruction
- Extra vs. intra-luminal
- Recognition and planning with surgeon - Dynamic hyperinflation
- Know how to recognise and choose appropriate ventilation strategy - Mediastinal shifts
- Lateral positioning / pleural effusions / PTX
Name 5 complications of thoracic surgery
- PPCs (postoperative pulmonary complications
- Atelectasis / pneumonia / PTX / pleural effusions / resp failure
- Inc risk with prolonged surgery, tissue handling
LPV and goal directed fluid therapy - Bronchopleural fistula
- Expecially right sided pneumonectomy - Cardiac arrythmias
- Especially after pneumonectomy - Pulmonary oedema
- Cardiac herniation - RARE, high mortality, shock, SVC obstruction, cyanosis, needs surgery
Anaesthetic “how to” - emergency thoracic sympathectomy
Pre-op:
Usually young, fit patients
Thorough cardiac work up - ?intractable angina , long QT
Preparation:
AAGBI standard monitoring
Art line if cardiac hx
Trained assistant
Wide bore IV access (occasional sig. blood loss)
Intra-op:
Airway - DLT, Single lumen with CO2 insuflation, single lumen bronchial blocker
Reinflate lung under direct vision then remove trochar
Local anaesthetic infiltration
Systemic analgesia: paracetamol, NSAID, opioid
Complications of ETS surgery?
- Bleeding risk
- Damage to subclavian/intercostal vessels
- Conversion to open thoracotomy - Dangers of insufflation
- Tension PTX
- Persistent PTX - Sympathetic blockade causing horner’s
- Persistent sweating elsewhere
- Hypoxaemia - DLETT, bronchial blocks
How to manage hypoxaemia during one-lung ventilation - just specifics, not all the phases
Increase FiO2 to 1.0
Suction catheter to lumen
Check position of DLT using fibreoptic scope
Check circuit, connection and anaesthetic machine
Insufflate oxygen to non-ventilated lung using suction cathter
Apply PEEP to ventilated lung (may worsen shunt)
Apply CPAP 5-10cm to non-ventilated lung, may improve shunt when PEEP applied to dependant lung
Intermittent inflation of collapsed lung i.e. 2 lung ventilation
Clamp pulmonary artery (in pneumonectomy)
Airway management options in massive haematemesis
- Uncut single-lumen tube (large as can be)
- Suction blood clots, may be tricky with flexi scope
- Guide bronchial blocker into BLEEDING lung
- Railroad single lumen tube into NON BLEEDING lung to protect it from contamination if B blocker not available - DLT
- May be tricky if bleeding
- May not have wide enough lumen to accomodate standard flexi bronchoscope
Non-surgical options to manage bleeding in patient intubated with haematemesis
- Tamponade - use bronchial blocker
- Ice cold saline lavage
- Vasoconstrictor usage adrenaline 1:20,000 instilled
- Rigid bronchoscopy
- Interventional radiology e.g. to bronchial vessels
