What is the standard of care for anesthesia in spine surgery?

Standard of Care for Anesthesia in Spine Surgery

For spine surgery, general anesthesia with comprehensive intraoperative monitoring (ECG, SpO2, NIBP, capnography, quantitative neuromuscular monitoring when paralytics are used, and processed EEG when TIVA is administered) represents the standard of care, though spinal anesthesia is a reasonable alternative for selected lumbar procedures of short duration.

Core Monitoring Requirements

The 2021 Association of Anaesthetists guidelines establish mandatory monitoring standards that apply to all spine surgery cases 1:

Minimum monitoring must include:

• ECG - continuous throughout
• SpO2 (pulse oximetry) - continuous throughout
• NIBP (non-invasive blood pressure) - continuous throughout
• Capnography - mandatory from induction through recovery until airway device removal and verbal response re-established
• Core temperature monitoring - routine use recommended
• Age-adjusted MAC monitoring when using inhaled anesthetics

Additional mandatory monitoring when specific techniques are used:

• Quantitative neuromuscular monitoring - required whenever neuromuscular blocking drugs are administered, continuing until train-of-four ratio >0.9 confirmed 1
• Processed EEG (pEEG) monitoring - mandatory when TIVA is combined with neuromuscular blockade; should be considered for high-risk patients and during inhalational anesthesia 1

An anesthetist must be continuously present throughout the entire procedure - this is non-negotiable 1.

Anesthetic Technique Selection

General Anesthesia (Primary Standard)

General anesthesia remains the predominant technique for spine surgery 2. The approach should include:

Induction considerations:

• Reduced doses of intravenous induction agents, particularly in elderly or compromised patients 3
• Inhalational induction is well-tolerated in elderly patients and maintains spontaneous ventilation 3

Airway management:

• Tracheal intubation with mechanical ventilation is standard for most spine procedures
• While paralysis and intubation cause greater physiological derangement than spontaneous ventilation, mechanical ventilation reduces aspiration risk and allows better CO2 control 3
• Higher inspired oxygen concentrations may be required as intraoperative hypoxemia is common 3

Monitoring during GA:

• All standard monitors as outlined above
• Point-of-care hemoglobin analyzers should be used routinely at surgery end to assess anemia and guide transfusion 3
• Somatosensory evoked potential (SSEP) monitoring is available at 94% of institutions and utilized in approximately 75% of major spine cases 2
• Motor evoked potential monitoring is available at 50% of institutions 2

Spinal Anesthesia (Alternative for Selected Cases)

Spinal anesthesia is a reasonable alternative for lumbar spine procedures of short duration in appropriately selected patients 4, 5. Recent evidence suggests potential benefits including:

• Shorter operative time (class III credibility) 5
• Reduced length of stay (class III credibility) 5
• Lower intraoperative blood loss (class IV credibility) 5
• Less postoperative nausea and vomiting 4, 5
• Lower early pain scores 4
• Reduced postoperative analgesic requirements 5

Critical monitoring requirements for spinal anesthesia:

• ECG, NIBP, and SpO2 must begin before the procedure and continue for at least 30 minutes after block completion 1
• Supplemental oxygen should always be provided 3

Important caveats:

• Evidence quality is low-to-moderate with substantial heterogeneity 4, 5
• Many anesthesiologists lack familiarity with this technique for spine surgery 6
• Airway management concerns in prone position and variable surgery duration are significant barriers 6
• Do not combine spinal and general anesthesia simultaneously - this is associated with precipitous intraoperative hypotension 3

Multimodal Analgesia Strategy

Opioids as sole adjunct to anesthesia should be avoided due to respiratory depression and postoperative confusion risk 3.

Recommended multimodal approach includes 7:

• Pregabalin or gabapentin
• COX inhibitors
• Acetaminophen
• Judicious opioid use only when other modalities optimized
• Consider peripheral nerve blockade as adjunct to extend postoperative non-opioid analgesia 3
• Local anesthetic infiltration (evidence for liposomal bupivacaine is mixed and requires more robust trials) 7

Blood Conservation

The two most frequent strategies utilized are 2:

1. Intraoperative cell salvage
2. Autologous blood donation

Common Pitfalls to Avoid

1. Never administer spinal and general anesthesia simultaneously - precipitous hypotension will occur 3
2. Do not rely solely on opioids for analgesia - use multimodal approach 3
3. Do not disable audible alarms - they must remain enabled with patient-specific limits 1
4. Do not remove capnography monitoring prematurely - continue until airway device removed and verbal response established 1
5. Do not extubate without confirming adequate neuromuscular recovery - train-of-four ratio must be >0.9 when paralytics were used 1

Documentation

An accurate anesthetic record summarizing all monitoring data is mandatory. Automated electronic anesthetic record systems integrated into the hospital's electronic health record are recommended 1.