What are the anaesthetic considerations and management for patients undergoing thoracic surgery?

Anaesthetic Considerations and Management for Thoracic Surgery

Preoperative Assessment

Comprehensive preoperative evaluation must prioritize cardiac, pulmonary, and renal function assessment, as these directly impact perioperative morbidity and mortality. 1

Cardiac Evaluation

• Patients older than 40 years or those with history of MI, angina, or heart failure require cardiac evaluation with echocardiography and potentially cardiac catheterization 1
• Elderly patients with thoracic disease commonly have coexisting coronary artery disease, though the benefit of prior coronary revascularization remains controversial 1
• Carotid duplex imaging and brachiocephalic angiography should be performed in patients with stroke history, TIA, or cerebrovascular risk factors to minimize stroke risk 1

Pulmonary Assessment

• Smoking history and chronic pulmonary disease are the most important predictors of postoperative respiratory complications 1
• Pulmonary function tests and arterial blood gas analyses are essential for risk stratification in patients with chronic lung disease 1
• Administer antibiotics and bronchodilators for reversible restrictive disease or excessive sputum production; smoking cessation is mandatory 1

Renal Function

• Preoperative renal dysfunction is the single most important predictor of acute renal failure after thoracic aortic operations 1
• Preoperative hydration and avoidance of hypotension, low cardiac output, and hypovolemia are critical preventive measures 1

Intraoperative Anaesthetic Management

Anaesthetic Technique Selection

The choice of anaesthetic techniques and agents must be tailored to individual patient needs to facilitate surgical and perfusion techniques while monitoring hemodynamics and organ function (Class I recommendation). 1

General Anaesthesia Approach

• General anaesthesia with endotracheal intubation using volatile halogenated agents (sevoflurane or isoflurane) with opioid supplementation is the standard approach 1, 2
• Propofol or etomidate for induction, with fentanyl or remifentanil for intraoperative analgesia 1
• Use intermediate-acting nondepolarizing neuromuscular blockers (rocuronium, vecuronium) rather than pancuronium, which causes higher intraoperative heart rates and delayed extubation 1
• Adequate neuromuscular blockade confirmed by peripheral nerve stimulator is mandatory before all airway interventions 1

Airway Management and Lung Isolation

Double-lumen endotracheal tubes or endobronchial blockers are essential for surgical exposure in open thoracic procedures, providing better visualization, reduced pulmonary retraction, and protection from contamination. 1

Critical Safety Considerations:

• Pre-oxygenation to achieve end-tidal oxygen concentration >90% before all airway interventions 1
• Release positive pressure within the breathing circuit by opening the adjustable pressure-limiting valve before airway interventions 1
• Large descending thoracic aneurysms may compress the left main bronchus—use right-sided tubes with caution and confirm position endoscopically 1
• Forceful endobronchial tube placement risks thoracic aortic aneurysm rupture; alternative methods may be required with severe airway distortion 1
• Do not routinely change double-lumen tubes to single-lumen tubes when significant upper airway edema or hemorrhage is present (Class III recommendation) 1

Monitoring Requirements

Transesophageal echocardiography (TEE) is reasonable in all open surgical repairs of the thoracic aorta unless specific contraindications exist (Class IIa recommendation). 1

• TEE provides critical intraoperative assessment of aortic valve function, dissection extent, pericardial/pleural effusions, and appropriate flow in the true lumen 1
• Motor or somatosensory evoked potential monitoring can be useful when data will guide therapy, based on individual patient needs and surgical techniques 1
• Standard monitoring includes ECG, pulse oximetry, non-invasive blood pressure, capnography, temperature, and neuromuscular monitoring 3

Regional Anaesthesia Considerations

Regional anaesthetic techniques are NOT recommended in patients at risk of neuraxial hematoma formation due to thienopyridine antiplatelet therapy, low-molecular-weight heparins, or clinically significant anticoagulation (Class III recommendation). 1

Thoracic Epidural Anaesthesia (TEA):

• TEA combined with general anaesthesia maintains better arterial oxygenation during one-lung ventilation compared to total IV anaesthesia alone 4
• TEA prevents the significant increase in cardiac output seen with one-lung ventilation, potentially benefiting patients with preexisting cardiopulmonary disease 4
• However, concerns about neuraxial bleeding with heparinization, platelet inhibitors, and CPB-induced thrombocytopenia limit routine use in many centers 1
• Consideration should be given to performing thoracic epidural anaesthesia in high-risk surgery for patients with cardiac disease (Class IIa recommendation) 1

Ventilation Strategy During One-Lung Ventilation

Protective lung ventilation strategies should include small tidal volumes, positive end-expiratory pressure, low peak and plateau airway pressures, low inspired oxygen fraction, and minimized surgical time. 5

• These strategies may not prevent acute lung injury but can decrease overall lung injury magnitude 5
• One-lung ventilation itself contributes to pulmonary complications despite being essential for surgical visualization 5

Fluid Management

• Ensure adequate intravascular volume with careful fluid administration 3
• Target near-zero fluid balance 3
• Be prepared for potential rapid blood loss with appropriate vascular access and blood products available 3

Temperature Management

• Maintain normothermia (core temperature ≥36°C) with active warming for operations lasting longer than 30 minutes 3
• Continuous core temperature monitoring is crucial 3

Postoperative Pain Management

A multimodal analgesic strategy combining regional anaesthesia with scheduled paracetamol and NSAIDs provides optimal pain control after thoracotomy, with opioids reserved strictly as rescue medication. 6

Regional Anaesthesia: First-Line Treatment

Paravertebral block is the primary recommended regional technique for thoracotomy pain management due to superior efficacy and fewer side effects compared to thoracic epidural analgesia. 6

• Erector spinae plane (ESP) block is equally recommended as a first-choice alternative to paravertebral block, demonstrating non-inferiority with potentially easier placement and fewer complications 6
• Continuous catheter infusion is preferred over intermittent bolus techniques 6
• For thoracoscopic procedures, ultrasound-guided continuous paravertebral block with long-acting local anaesthetic combined with clonidine is recommended 6

Systemic Multimodal Analgesia

Paracetamol should be administered pre-operatively or intra-operatively and continued at regular intervals postoperatively as foundational multimodal analgesia. 6

• NSAIDs or COX-2 inhibitors should be initiated pre-operatively or intra-operatively and continued postoperatively unless contraindicated by renal impairment, heart failure, or bleeding risk 6
• NSAIDs and COX-2 inhibitors are NOT recommended for postoperative pain control in patients with renal and heart failure, myocardial ischaemia, elderly patients, or those taking diuretics or having unstable haemodynamics (Class III recommendation) 1
• Short-course NSAID therapy improves pain control, enhances recovery, and reduces hospital length of stay 6
• A combination of two non-opioid drugs (NSAID, metamizole, paracetamol) should always be used to reduce opioid rescue requirements 6

Opioid Management

Opioids should be used exclusively as rescue analgesics for breakthrough pain, not as primary analgesics in the multimodal regimen. 6

• For immediate post-procedure breakthrough pain, intravenous fentanyl in divided doses is the preferred opioid 6
• Consider IV patient-controlled analgesia with adequate monitoring for patients requiring frequent rescue dosing 6
• Intravenous morphine or other suitable agent as rescue with pulse oximetry monitoring 6

Adjunctive Therapies

• Methylprednisolone or dexamethasone to reduce postoperative swelling 6
• Intraoperative addition of alpha-2 agonists (clonidine) as adjunct to regional anaesthesia 6
• Intraoperative ketamine as co-analgesic drug 6
• Local wound infiltration or port-side infiltration with long-acting local anaesthetic 6
• Intravenous lidocaine as alternative 6

Critical Implementation Algorithm

1. Continue scheduled paracetamol and NSAID (oral or IV) during entire postoperative period 6
2. Continue regional anaesthesia infusion 6
3. Transition to oral medications as soon as tolerated 6
4. Aggressive early mobilization and chest physiotherapy once pain is controlled 6

Special Considerations

COVID-19 Pandemic Modifications

• Minimize staff present during aerosol-generating procedures 1
• Use appropriately placed HEPA viral filters and clamps when opening double-lumen tubes to atmosphere 1
• Only open double-lumen tube to atmosphere after releasing positive pressure through HEPA filter 1
• Flexible bronchoscopes pose significant contamination risks—store in designated area and dispose of outer gloves after use 1

Pediatric Neurotoxicity Warning

• Anesthetic agents blocking NMDA receptors and/or potentiating GABA activity increase neuronal apoptosis in developing brains when used >3 hours 2
• The vulnerability window correlates with third trimester through first several months of life, potentially extending to three years 2
• No specific medications have been shown safer than others; decisions should weigh procedure benefits against potential risks 2

Malignant Hyperthermia Risk

• Sevoflurane can trigger malignant hyperthermia in susceptible individuals, particularly with concomitant succinylcholine administration 2
• Early signs include hyperthermia, hypoxia, hypercapnia, muscle rigidity, tachycardia, and hemodynamic instability 2
• If suspected, immediately discontinue all triggering agents, administer IV dantrolene sodium, and initiate supportive therapies 2

Enhanced Recovery Considerations

• Enhanced recovery after thoracic surgery aims to improve organ function, decrease postoperative complications, and reduce hospital length of stay 5
• Elements include multimodal analgesia, early mobilization, optimized fluid management, and prevention of thromboembolism 7