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Thoracic Analgesia

Thoracic Incisions

Median Sternotomy and Partial Sternotomy

• Allow access to midline structures.

Thoracotomy Incisions

• Determined by their relationship to the latissimus dorsi muscle.
  • Standard Posterolateral Thoracotomy:
    • Transects the latissimus dorsi muscle.
    • Provides good exposure to the entire hemithorax, including lung, oesophagus, mediastinum, cardiac structures, and the aorta on the left.
  • Anterolateral Thoracotomy:
    • Transects the serratus anterior muscle.
    • Used in minimally invasive cardiac and thoracic surgery, trauma front room thoracotomy for rapid access to the aorta, pericardium, and other structures.

Anatomy and Physiology

Sensory Afferents

• Skin incision and intercostal muscles: Intercostal nerves T4–T6.
• Chest drains: Intercostal nerves T7–T8.
• Mediastinal pleura, lung, and mediastinal structures: Vagus nerve (CN X).
• Central diaphragmatic pleura: Phrenic nerve (C3–C5).
• Ipsilateral shoulder: Brachial plexus.
• Parietal pleura: Innervated by intercostal and phrenic nerves; pain-sensitive.
• Visceral pleura: Sensitive mainly to stretch.
• Latissimus dorsi and serratus anterior muscles: Thoracodorsal and long thoracic nerves (C5 to C7 roots of the brachial plexus).

Reasons for Intense Pain

• Muscle division, rib retraction or resection, and destruction of the intercostal nerves.
• Posterolateral thoracotomy incision spans approximately six dermatomes, from the third dermatome posteriorly to the seventh or eighth dermatome anteriorly.
• Up to three chest drains may be required after thoracotomy, often inserted in the eighth or ninth intercostal space, which falls outside the analgesia provided by the epidural or paravertebral block.
• No single analgesic technique can inhibit all these pain afferents.

Epidemiology and Importance

• Persistent Pain:
  • 25% of patients experience moderate to severe pain at six months post-thoracotomy.
  • Severely affects the quality of life in 40% of these patients.
• Risk Factors for Chronic Post-Thoracotomy Pain:
  • Male sex, age > 60 years, preoperative pain, and acute pain postoperatively.
  • Incidence: 30%–60%.
• Consequences of Poor Analgesia:
  • Poor ventilatory mechanics, shallow breathing, impaired coughing leading to atelectasis, retention of secretions, hypoxaemia, hypercapnia, and respiratory failure.
  • Cardiovascular dysfunction due to increased sympathetic tone resulting in increased myocardial oxygen demand, afterload, myocardial dysfunction, and arrhythmias.
  • Increased incidence of deep venous thrombosis and pulmonary embolism.
  • Longer hospital stays and increased ICU admissions.

Choice of Analgesic Technique

• Ideal technique includes opioids (PCA), anti-inflammatory agents, and local anesthetics (epidural, intrathecal, paravertebral blocks, intercostal nerve blocks, cryoprobe neurolysis).

Surgical Strategies

• Non-spreading VATS procedures, muscle-sparing techniques, less rib retraction, and rib preservation.
• Strict layered closure, approximating each individual layer of muscle correctly, and avoiding over-approximation of the ribs.

Systemic Agents

• Opioids: Effective for background pain but not for acute pain with cough or movement.
• NSAIDs and Paracetamol:
  • Reduce opioid consumption by more than 30% after thoracotomy.
  • Particularly useful for treating ipsilateral shoulder pain postoperatively.
• Ketamine:
  • Low-dose intravenous infusions may be effective for refractory pain or contraindications to more common techniques.
• Dexmedetomidine:
  • Maintenance infusion doses for analgesia: 0.3 to 0.4 μg/kg/hr.

Nerve Blocks

Intercostal Nerve Blocks

• Placed near the posterior axillary line to cover the lateral cutaneous branch of the intercostal nerve.
• Total bupivacaine dose should not exceed 1 mg/kg.

Interpleural Analgesia

• Unreliable in its analgesic effect.

Cryoprobe Neurolysis and TENS

• Cryoprobe Neurolysis:
  • Application of a −60 °C probe to the exposed intercostal nerves intraoperatively.
  • Produces an intercostal block lasting up to six months but associated with chronic neuralgia.
• TENS:
  • Useful in mild to moderate pain but ineffective for severe pain.

Paravertebral Blocks

• Paravertebral space is deep to the endothoracic fascia.
• Provides sensory and sympathetic block of multiple thoracic dermatomes unilaterally or bilaterally.
• Comparable to thoracic epidural infusion for post-thoracotomy pain.
• Advantages:
  • Comparable analgesia, fewer failed blocks, decreased risk of neuraxial hematoma, less hypotension, nausea, or urinary retention.
• Disadvantages:
  • Single-level block may only cover 2 to 4 dermatomes, requiring multiple injections.
  • Cannot be used in patients on antithrombotic or thrombolytic therapy.

Serratus Anterior Plane (SAP) Block

• Considered the transversus abdominis plane (TAP) block of the chest wall.
• Local anesthetic into the facial plane superficial or deep to the serratus anterior muscle.
• Blocks the lateral cutaneous branches of the intercostal nerves T2 to T9.
• Advantages:
  • No autonomic block, risk of pleural puncture, or serious spinal cord injury.
  • Complements thoracic PVB, TEA, or intercostal nerve blocks for chest drain-related pain.
  • Easy to perform.

Continuous Erector Spinae Plane (ESP) Block

• Local anesthetic is injected into the tissue plane deep to erector spinae muscle but superficial to the transverse processes.
• Promotes extensive craniocaudal spread of local anesthetic, providing good analgesia.
• Simple to perform using ultrasound, with reduced risk of pleural puncture and epidural spread.

Erector Spinae Plane Block

Indications:

• Analgesia for rib fractures
• Back and chest wall surgeries

Goal:

• Injection of local anesthetic in the plane deep to the erector spinae muscles and superficial to the transverse processes, to achieve a craniocaudal distribution along several vertebral levels.

Equipment:

• Transducer: Linear or curved
• Needle: 22 gauge, 5-10 cm short bevel
• Local Anesthetic Volume: 20-30 mL

Essential Fact:

• At higher thoracic levels, e.g., above T5, the trapezius, rhomboid major, and erector spinae muscles can be identified as three layers superficial to the transverse processes. In the lower and mid-thoracic levels, only the trapezius and erector spinae muscles can be seen.

Thoracic Epidural Analgesia (TEA)

• Gold standard for post-thoracic and upper abdominal surgery analgesia.
• Failure rate of 15% and poor coverage of chest-tube insertion sites.
• Commonly placed between T3 and T8 with bupivacaine and fentanyl or hydromorphone infusions.
• Synergy: Opioids and local anesthetics produce segmental epidural analgesia.
• Lipid-Soluble Agents:
  • E.g., fentanyl, sufentanil; narrow dermatomal spread, rapid onset, low incidence of pruritus/nausea.
  • Significant systemic effects when used as epidural infusions.
• Hydrophilic Opioids:
  • E.g., morphine, hydromorphone; preferable for extensive incisions covering many dermatomes.
• Paramedian approach at mid-thoracic levels decreases the difficulty of placing thoracic epidurals.

Links

• Thoracic emergencies
• Thoracic pre-op assessment
• Truncal blocks
• Pain regional blocks

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References:

1. Shatri G, Singh A. Thoracic Segmental Spinal Anesthesia. [Updated 2023 Jul 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572087/
2. FRCA Mind Maps. (2024). Retrieved June 5, 2024, from https://www.frcamindmaps.org/
3. Anesthesia Considerations. (2024). Retrieved June 5, 2024, from https://www.anesthesiaconsiderations.com/

Summaris
Thoracic Anaesthesia
Thoracic anaesthesia analgesia

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© 2025 Francois Uys. All Rights Reserved.

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