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One Lung Anaesthesia

Last modified: 26 September 2022, 5:08:29 PM AEST

Gems1 / 10

attempts to treat hypoxia with OLV may worsen hypoxia\n
- ⬆O2 upper lung = ⬇HPV = ⬆BQ = ⬆shunt
- ⬆PEEP to ventilated lung
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Description2 / 10

deliberate intraoperative collapse of one lung
maintain oxygenation and ventilation with the other lung

Physiology3 / 10

lateral position = awake\n
- upper lung = ⬆FRC, ⬆compliance
- lower lung = ⬆ventilation, ⬆perfusion (gravity) = better V/Q matching
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lateral position = anaesthetised\n
- upper lung = ⬇FRC\n
  - SHUNT = perfused, but not ventilated
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- lower lung = ⬇FRC (pressure of mediastinum), ⬆perfusion = ⬆V/Q mismatch
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Indications (Absolute)4 / 10

Protection\n
- prevent cross-contamination = blood, pus
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Ventilation = Pathological impact of PPV\n
- control distribution of ventilation, eg. bronchopleural fistula
- ineffective ventilation (with ICC in situ)
- tension PTX (without ICC)
- systemic air embolus
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Lavage\n
- Cystic fibrosis
- Pulmonary alveolar proteinosis
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Indications (Relative)5 / 10

Surgery (Strong)\n
- Thoracic, oesophageal, and mediastinal surgery
- Thoracic aortic aneurysm
- Pneumonectomy
- Lung volume reduction surgery
- Minimally invasive cardiac surgery
- Upper lobectomy
- Video Assisted Thorascopic Surgery
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Surgery (Weaker)\n
- Oesophageal Surgery
- Middle and lower lobectomy
- Mediastinal mass reduction
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Preop assessment6 / 10

PPO = Predicted Post-Operative
based on anatomic calculation, V/Q scans / CT scans
PPO FEV1
DLCO
PPO FEV1 / DLCO\n
- 60% = low risk
- 30-60% = intermediate\n
  - ET, eg shuttle walk assessment; good = low risk
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high risk\n
- PPO FEV1 / DLCO < 30%
- poor exercise tolerance
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CPT for high risk patients\n
- VO2max > 10 mL/kg/min = moderate risk
- VO2 max < 10 mL/kg/min = high risk
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Technique7 / 10

TV 4-5 mL/kg\n
- balance between\n
  - ⬆Paw
  - atelectasis
  \n
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be prepared to suction lower lung
suction upper lung before re-inflating

Airway Options8 / 10

DLT\n
- Left
- Right
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Bronchial blockers\n
- Arndt = Yellow
- Cohen = Green
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SLT\n
- Endotracheal tube
- Endobronchial tube
- Parkerflex tube
- MLT tube
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Common questions / related topics9 / 10

Hypoxia on OLV

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Risk factors
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- Operative lung = high V/Q on scan
- Low PaO2 during 2-lung ventilation
- Right thoracotomy
- Normal FEV1/FVC / Restrictive lung disease
- Supine position during OLV
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Approach
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- Consider WAKING UP
- Treat reversible causes
- Improve physiology for OLV
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Key points
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- 100% O2
- FOB + suction + check position
- Lower lung = Optimise PEEP lower lung 5-8 cm H2O, minimise HPV
- Upper lung = catheter, PEEP device 1-2 cm H2O
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A = Airway
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100% O2
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- caution loss of N2 splinting
- Except if bleomycin
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take over manual ventilation of patient
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causes
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- disconnection
- dislodgement = re-check DLT position with FB
- SECRETIONS = SUCTION / bronchoscopy
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B = Ventilation
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auscultate chest
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check compliance
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check capnograph waveform
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causes
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- bronchospasm = bronchoD
- PTX of ventilated lung = decompression
- inadequate NMB = re-paralyse
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Recruitment
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- Transient ⬇BP and transient hypoxia if more blood is diverted to non-ventilated lung
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C = Circulation
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Optimise haemodynamics
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correct hypotension / optimise CO
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causes
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- hypotension = ⬇BQ = worse VQMM
- check for haemorrhage
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if assessment is normal, then cause is likely physiology from OLV
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management
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B = Ventilation
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- 1: lower / ventilated / non-operative lung\n
  - recruitment manoeuvre = improve FRC
  - maintain normocarbia = minimise HPV (⬇BQ)
  - ⬆PEEP = to counteract the effect of mediastinal weight on FRC\n
    - 5 cm H2O
    - can check compliance curves on machine to determine ideal PEEP ***
    \n
  - ⬆Paw = to ⬆Vt (caution ⬆Paw, causing ⬇BQ)
  - caution = ⬆⬆PEEP = ⬇BQ (lung volume) = ⬆Vd
  - \"optimal PEEP\"
  \n
- 2: upper / non-ventilated / operative lung\n
  - main problem is SHUNT = BQ without ventilation
  - reduce shunt = ⬆ventilation
  - CPAP = inform surgeons\n
    - CPAP connector
    - 1-2 cm H2O
    \n
  - O2 insufflation via suction catheter (give O2, without ventilating)\n
    - 300 mL/min
    - can also use T-piece connected to auxiliary O2
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  - high-frequency oscillatory ventilation
  - intermittent 2-lung ventilation\n
    - ie. intermittent reinflation
    - improves HPV reflex by repeated hypoxic exposures
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  - caution = ⬆FiO2 = ⬇HPV = ⬆BQ = ⬆shunt
  - Clamp pulmonary A
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C = Circulation
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- upper lung\n
  - ONLY IF pneumonectomy, early clamping / surgical ligation of PA
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- optimise CO / Hb to ensure O2 delivery\n
  - doesn't improve hypoxia but mitigates its effects
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if intractable
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- 2-lung ventilation\n
  - or intermittent ventilation of operative side
  - increases difficulty for surgeon
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- ECMO (V-V ECMO)
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When to inform surgeon about hypoxia on OLV

When PEEP > 8 in lower lung
When intermittent ventilation may be required
Good practice to have predefined limits, eg. SpO2 90

References10 / 10

Final FRCA In A Box
Final FRCA SAQs

Hypoxic pulmonary vasoconstriction, BJAE 2017

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