2. 1. Anesthetic Techniques
• Anesthesia begins with intravenous induction for patient comfort.
• Endobronchial intubation, particularly with double-lumen tubes
(DLTs), is vital for lung isolation.
• The choice between inhalational agents and intravenous techniques
depends on various factors, including the nature of the surgery.
3. Table 10.1 Anaesthetic techniques suitable for major thoracic surgery
Induction
Propofol
Satisfactory in most patients; repeat, as necessary, to prevent awareness during preoperative bronchoscopy.
Target-controlled infusion useful for longer procedures and prolonged bronchoscopy
Etomidate
Elderly or those with cardiovascular instability
Neuromuscular blockade
Choice of non-depolarizing agent not critical
Consider suxamethonium for difficult intubation, or airway fistula
Maintenance of anaesthesia
Inhalational agent
Isoflurane most suitable
Avoid halothane: has marked inhibitory effect on hypoxic pulmonary vasoconstriction
Inspired gas mixture: 50% oxygen in nitrous oxide or air
Avoid nitrous oxide with abnormal air spaces
Increase inspired oxygen concentration for one-lung ventilation (air/oxygen combination preferable)
Total intravenous anesthesia
Propofol by target controlled infusion: combine with remifentanil infusion?
Intraoperative analgesia
Morphine (0.1–0.2 mg/kg) based on age/physical status, etc., supplement at end of surgery
Fentanyl (5–15 µg/kg): alternative
Avoid intravenous opioids if epidural opioids used
Epidural analgesia
Thoracic/high lumbar/lumbar: all feasible
Opioids alone or combined with low-dose local anesthetic agents
Anaesthesia
for
thoracic
surgery
129
4.
5. 2. Monitoring
• Comprehensive monitoring involves tracking vital signs such as heart
rate, blood pressure, and oxygen levels.
• While routine use of pulmonary artery catheters is debated, other
forms of invasive monitoring might be employed based on the
complexity of the thoracic surgery.
6. Table 10.2 Monitoring: major thoracic surgery
• Electrocardiogram
• Pulse oximetry
• End-tidal gas analysis
Oxygen
Carbon dioxide (invaluable during one-lung ventilation) Inhalational
agent
• Flow/volume loop
Useful during one-lung ventilation
• Invasive arterial pressure measurement
Arterial cannula in radial artery contralateral to side of surgery because of
the position of the arm
• Central venous pressure measurement/volume line
Multilumen catheter in the internal jugular on the side of surgery
• Nasopharyngeal temperature
Heat loss significant during thoracotomy
• Urinary output measurement
7. 3. Lung Isolation
• Lung isolation is a critical aspect of thoracic surgery to facilitate one-
lung ventilation (OLV).
• Various techniques are employed, including double-lumen tubes
(DLTs), bronchial blockers, and Univent tubes.
• DLTs have a tracheal limb and an endobronchial limb with cuffs for
sealing. Bronchial blockers selectively block individual lobes, and the
Univent tube combines an endotracheal tube with a movable bronchial
blocker.
• The choice depends on the surgical requirements and the patient's
condition.
8. Tracheal limb Pilot balloon-tracheal cuff
Bronchial
limb
Pilot balloon-bronchial cuff
Tracheal cuff
Tracheal ventilation
lumen for left lung
Bronchial cuff
Oropharyngeal curve Bronchial curve
Ventilation slot for
upper right lobe
Endobronchial
ventilation lumen
to middle and
lower lobes
Basic pattern of a right-sided double-lumen endobronchial
tube
9. 4. Placement of DLT
• Proper placement of the double-lumen tube (DLT) is crucial for
effective lung isolation.
• Clinical checks involve observing chest movements and auscultation.
Fiberoptic bronchoscopy (FOB) is increasingly preferred for its
precision.
• The FOB is used to ensure a clear view of the main bronchus, confirm
proper placement of cuffs, and assess any obstructions.
10.
11. 5. Bronchial Blockade
• Bronchial blockers and Univent tubes offer flexibility in selectively
blocking lobes during OLV.
• The Univent tube integrates a movable bronchial blocker within the
endotracheal tube, allowing precise control over lung isolation.
• This technique is particularly useful for certain thoracoscopic surgeries
where collapsing the lung on the side of the surgery is necessary for
safe access.
12. 6. Ventilation during Thoracotomy
• The lateral position during thoracotomy presents physiological
challenges.
• Inspiratory muscle tone decreases, and lung volume reduces.
• Paralysis and intermittent positive pressure ventilation are used, and
selective ventilation of the lower lung (OLV) is common to facilitate
surgical access.
• However, this introduces issues like ventilation/perfusion mismatch,
requiring careful management.
13. 7. Hypoxic Pulmonary Vasoconstriction
• Hypoxic pulmonary vasoconstriction (HPV) is a mechanism diverting
blood flow away from hypoxic or collapsed lung areas during OLV.
• Volatile anesthetic agents can depress HPV, while intravenous agents
like propofol might enhance arterial oxygenation during OLV.
• Understanding and managing HPV are crucial for optimizing
oxygenation during thoracotomy.
14. 8. Cardiac Output
• Changes in cardiac output during thoracotomy can impact arterial
oxygenation.
• Factors like blood loss, fluid depletion, high inflation pressures, and
the application of positive end-expiratory pressure (PEEP) to the
dependent lung can decrease cardiac output.
• Surgical manipulations around the mediastinum, leading to a reduction
in venous return, are common causes of sudden drops in cardiac output
during lung resection.
15. 9. Principles of Ventilation
• Optimal one-lung ventilation (OLV) requires adequate lung inflation
while minimizing intra-alveolar pressure.
• Overinflating the single lung can lead to 'volutrauma,' contributing to
acute lung injury.
• Limiting ventilation to low tidal volumes is essential to improve
outcomes, particularly in patients with adult respiratory distress
syndrome.
16. 10. Hypoxia during One-Lung Ventilation
• Predicting which patients are likely to experience hypoxemia during
OLV is challenging.
• Monitoring oxygen saturation (SpO2) and adjusting the position of the
endobronchial tube are essential if hypoxia occurs.
• Measures to improve oxygenation include increasing inspired oxygen
concentration, introducing PEEP to the dependent lung, or supplying
oxygen to the upper lung.
17. 11. High-Frequency Jet Ventilation
• High-frequency jet ventilation (HFJV) is an alternative ventilation
method during thoracotomy, using either endotracheal or
endobronchial tubes.
• HFJV provides ventilation with low peak airway pressures, but its
adoption is limited due to challenges in administering gaseous
anesthetic agents and difficulties with surgical access when the lung is
distended.
18. 12. New Modalities and One-Lung
Anesthesia
• Ongoing research explores new modalities to reduce hypoxia during
one-lung anesthesia.
• Pharmacological manipulation of pulmonary blood flow using
substances like prostaglandin E1 and nitric oxide is an area of interest
for improving outcomes during OLV.
19. 13. Termination of Surgery and Anesthesia
• After completing lung resection, testing for air leaks in bronchial
suture lines and lung surfaces is crucial.
• Sterile water is instilled into the pleural cavity, and any leaks are
identified through the appearance of gas bubbles.
• The termination of anesthesia involves steps such as lightening
anesthesia, re-establishing spontaneous ventilation, and ensuring
proper reinflation of the lungs.
• Postoperative care is often supervised in a high-dependency or
intensive care unit, ensuring the patient's stable recovery.
