One-Lung Ventilation (OLV): Thoracic Anaesthesia Cheat Sheet

For trained anaesthesia clinicians. Follow local thoracic, ICU, and surgical protocols.

1. Physiology of OLV

What changes?

• The non-dependent operative lung is collapsed and not ventilated but remains perfused.
• This creates an obligatory right-to-left intrapulmonary shunt.
• The dependent lung receives all delivered tidal volume and is prone to:
  • Atelectasis from lateral positioning, anaesthesia, paralysis, mediastinal compression, and secretions
  • Barotrauma/volutrauma if tidal volume or pressures are excessive
  • Hyperinflation and auto-PEEP, particularly in COPD

1. Perfusion of the non-ventilated lung, producing shunt.
2. Atelectasis or low V/Q in the dependent ventilated lung.
   Miller’s Anesthesia, 10e, p. 1318.

Hypoxic pulmonary vasoconstriction (HPV)

• Hypoxia in the collapsed lung causes local pulmonary arteriolar constriction.
• Blood is diverted toward the oxygenated dependent lung.
• HPV begins within seconds, has an early phase over minutes, and reaches substantial effect by about 15-20 minutes.
• Despite HPV, shunt during OLV commonly remains around 20%-30%.

Factors that worsen oxygenation / inhibit HPV

• Hypoxia in the dependent lung
• Excessive airway pressure, excessive PEEP, hyperinflation
• Hypotension or low cardiac output
• Severe anaemia or low mixed venous oxygen saturation
• Excessive volatile anaesthetic concentrations
• Vasodilators delivered systemically
• Nitrous oxide
• Pulmonary vasodilators reaching the non-ventilated lung

2. Preoperative Assessment

Assess respiratory reserve

• Symptoms, exercise tolerance, recent infection/exacerbation, smoking, home oxygen, OSA.
• Spirometry and DLCO where lung resection is planned.
• ABG if severe disease, hypercapnia, hypoxaemia, or concern about CO2 retention.
• CT: tumour location, airway distortion, bullae, pleural adhesions, bronchial obstruction.
• Consider perfusion scan or predicted postoperative FEV1/DLCO for major resection.

Identify patients likely to desaturate during OLV

• Poor baseline oxygenation
• Low FEV1/DLCO, severe COPD, interstitial lung disease
• Contralateral lung disease
• Right-sided thoracic surgery, because the non-ventilated right lung usually represents more perfused lung
• Obesity
• Previous contralateral lung resection
• Pulmonary hypertension or impaired RV function
• Large shunt fraction or dependent-lung atelectasis

Preparation

• Discuss operation, anticipated OLV duration, need for CPAP or intermittent two-lung ventilation, risk of major haemorrhage, and postoperative destination.
• Large-bore IV access; arterial line for major resections, pneumonectomy, significant cardiopulmonary disease, or expected blood loss.
• Blood available for major resections/decortication.
• Thoracic epidural, paravertebral block, erector spinae plane block, or surgeon-performed intercostal blocks according to operation and contraindications.
• Avoid routine sedative premedication in severe respiratory disease.

3. Lung Isolation

Device choice

DLT safety steps

1. Insert in supine position.
2. Confirm with flexible bronchoscopy.
3. Reconfirm after lateral positioning, after surgical manipulation, and whenever oxygenation or airway pressures change.
4. Maintain minimal effective bronchial cuff pressure.
5. Ensure a patent suction channel and facilitate lung deflation before pleural opening.

4. Standard OLV Ventilation Strategy

Initial settings

• FiO2: 1.0 at initiation of OLV, then reduce only if oxygenation is stable and clinically appropriate.
• Tidal volume: 4-6 mL/kg ideal body weight.
• PEEP: Begin about 5 cmH2O, then individualise.
• Respiratory rate: Adjust for pH/PaCO2. Mild permissive hypercapnia is often acceptable if haemodynamically tolerated.
• I:E: Allow adequate expiratory time, particularly in COPD.
• Plateau pressure: Aim <25-30 cmH2O.
• Driving pressure: Keep as low as practical. PEEP titration guided by compliance and driving pressure is reasonable.
• Recruitment manoeuvre of the dependent lung after positioning and after disconnection/reconnection, followed by individually titrated PEEP.

PEEP principle

Haemodynamics

• Maintain adequate MAP, preload, RV perfusion, and cardiac output.
• Avoid both fluid overload and reflexive under-resuscitation.
• Treat clinically relevant hypotension with small fluid challenges only when indicated and use vasopressors early where appropriate.
• Excessive inotropy can raise pulmonary blood flow and shunt; low cardiac output lowers mixed venous saturation and can markedly worsen arterial oxygenation.

5. Hypoxaemia During OLV: Immediate Algorithm

First: call for help and communicate with surgeon

• Inform surgeon immediately.
• Ask whether the operative field permits temporary reinflation, CPAP, or intermittent two-lung ventilation.
• If severe/refractory hypoxaemia: resume two-lung ventilation immediately.

Stepwise checklist

A. Ensure oxygen delivery

1. Set FiO2 1.0.
2. Check circuit, oxygen supply, ventilator, flowmeters, sampling line, and pulse oximeter waveform.
3. Manually ventilate if uncertain about mechanics or equipment.

B. Exclude DLT/blocker malposition or obstruction

1. Flexible bronchoscopy is the priority.
   • DLT displaced proximally or distally?
   • Bronchial cuff herniation?
   • Right upper-lobe obstruction by a right DLT?
   • Blood, secretions, mucus plug, tumour obstruction?
   • Kinked lumen or blocker migration?
2. Suction both lumens and correct tube/blocker position.

C. Optimise the dependent, ventilated lung

1. Check for:
   • Low tidal volume/minute ventilation
   • Dependent-lung atelectasis
   • Excessive PEEP or auto-PEEP
   • Bronchospasm
   • Pneumothorax of the dependent lung
   • Endobronchial secretions
2. Perform dependent-lung recruitment if appropriate.
3. Titrate PEEP using compliance, plateau pressure, driving pressure, and oxygenation.
4. Treat bronchospasm and clear secretions.
5. Avoid excessive tidal volume and high airway pressure.

D. Optimise perfusion and oxygen carrying capacity

1. Correct significant hypotension, low cardiac output, severe anaemia, arrhythmia, or major blood loss.
2. Maintain normothermia.
3. Avoid unnecessary pulmonary vasodilators and high concentrations of volatile anaesthetic.

E. Improve oxygenation from the operative lung

1. If surgery permits, apply CPAP 1-5 cmH2O with oxygen to the non-dependent lung.
   • Start low because higher CPAP can impair exposure.
   • In VATS, CPAP may significantly interfere with the field and is generally a later manoeuvre.
2. Consider apnoeic oxygen insufflation to the operative lung in selected cases.
3. Intermittent two-lung ventilation is appropriate if hypoxaemia is persistent or severe.

F. Rescue

1. Request temporary surgical pause and reinflation of the operative lung.
2. Convert surgical approach if necessary.
3. If oxygenation remains unacceptable, abandon OLV until the cause is corrected.

6. VATS Anaesthetic Management

Key differences from open thoracotomy

• Usually requires reliable lung isolation and complete operative-lung collapse.
• VATS port insertion occurs before the lung may be fully collapsed. During this phase, shunt can increase and desaturation may occur.
• Limited direct access to the patient after positioning and draping.
• High risk events: pulmonary artery injury, major haemorrhage, sudden conversion to thoracotomy, capnothorax-related hypotension/arrhythmia when CO2 insufflation is used.

VATS plan

• Standard monitoring plus arterial line for major resections/high-risk patients.
• Left DLT in most cases; bronchoscopy after positioning.
• Protective OLV, judicious fluids, temperature management.
• Have a clear conversion plan:
  • Access to patient’s airway
  • Unobstructed side for emergency thoracotomy
  • Rapid infusion/blood availability
  • Team briefing for massive haemorrhage
• Multimodal analgesia: paravertebral/ESP block or intercostal blocks plus regular non-opioids if appropriate.
• Encourage early extubation, mobilisation, chest physiotherapy, and nausea prophylaxis.

7. Pneumonectomy Management

Intraoperative

• Arterial line and large-bore access.
• Consider central access when vasoactive support, complex fluid management, or major blood loss is anticipated.
• Careful OLV: protect the future single remaining lung.
• Avoid fluid excess. Use haemodynamic assessment and vasopressors rather than indiscriminate fluid administration.
• Prevent hypoxaemia, hypercapnia, acidosis, hypothermia, and high airway pressures, all of which may increase pulmonary vascular resistance and RV load.
• Expect haemodynamic changes when the pulmonary artery is clamped and after lung removal.

Postoperative priorities

• Extubate early when feasible. Avoid prolonged positive-pressure ventilation.
• ICU/HDU monitoring for major comorbidity, right pneumonectomy, borderline physiology, significant blood loss, or intraoperative instability.
• Effective regional/multimodal analgesia to allow cough and mobilisation.
• Manage atrial fibrillation, ischaemia, RV failure, and hypoxaemia promptly.
• Chest radiograph on arrival in PACU/ICU to assess mediastinal position.

Postpneumonectomy chest drain warning

• Do not apply routine suction to an empty postpneumonectomy space.
• A standard underwater seal or suction can cause mediastinal shift and haemodynamic collapse.
• Drain management must follow the thoracic surgeon’s specified plan, often using no drain, a balanced system, or temporary controlled aspiration.

Postpneumonectomy pulmonary oedema / acute lung injury

• Restrictive, individualised fluid strategy
• Avoid excessive transfusion where possible
• Protective ventilation
• Avoid high airway pressures and unnecessary hyperoxia
• Early recognition of RV dysfunction and pulmonary hypertension

• ICU care
• Exclude cardiogenic oedema, aspiration, pneumonia, pulmonary embolism, transfusion-related lung injury, and bronchopleural fistula
• Conservative fluid strategy and gentle diuresis if volume overloaded
• Lung-protective ventilation if intubation is unavoidable
• Early senior thoracic, ICU, and cardiology input where RV failure is present

8. Pleural Decortication Management

Major anaesthetic issues

• Sepsis, malnutrition, anaemia, chronic infection, restrictive physiology, hypoxaemia.
• Dense pleural adhesions make lung collapse incomplete and surgical dissection prolonged.
• Bleeding can be substantial due to inflamed pleura/chest wall adhesions.
• Air leaks and visceral pleural injury are common.
• Re-expansion pulmonary oedema is a concern when a chronically collapsed lung is re-expanded.
• Severe postoperative pain impairs cough and secretion clearance.

Management plan

• Correct dehydration, electrolyte disorders, coagulopathy, and anaemia where possible.
• Culture-directed antimicrobial therapy for empyema.
• Assess sepsis, respiratory reserve, and contralateral lung.
• Plan blood availability and postoperative critical-care level.

• DLT usually preferred for suction, isolation, and intermittent reinflation.
• Arterial line and blood products for extensive decortication.
• Protective dependent-lung ventilation.
• Anticipate difficult exposure, incomplete deflation, sudden bleeding, air leaks, and conversion from VATS to thoracotomy.
• Avoid excessive fluids while maintaining perfusion.
• Re-expand the released lung gradually, with surgeon communication, and avoid aggressive high-pressure recruitment.

• Extubate if gas exchange, haemostasis, and temperature allow.
• Monitor for bleeding, persistent air leak, bronchopleural fistula, sepsis, recurrent collection, and re-expansion pulmonary oedema.
• Regional analgesia, humidification, chest physiotherapy, early mobilisation, and lung expansion measures.
• Chest drain strategy is surgical-pathology specific. Unlike pneumonectomy, decortication commonly requires drains, often with suction initially if the surgeon requests it.

9. Postoperative Thoracic Anaesthesia Bundle

• Multimodal analgesia plus regional technique when appropriate.
• Avoid oversedation and excessive opioids.
• Incentive spirometry or coached deep breathing where used locally.
• Cough support, chest physiotherapy, early mobilisation.
• VTE prophylaxis.
• Treat nausea so the patient can mobilise and cough.
• Watch for: atelectasis, pneumonia, air leak, bronchopleural fistula, bleeding, atrial fibrillation, pulmonary embolism, respiratory failure, and post-resection lung injury.

One-line exam summary