Patients with spinal cord injury (SCI) undergoing anesthesia require specialized care to address their unique needs and potential complications. The choice of anesthetic technique, monitoring, premedication, induction, maintenance, and other considerations should be tailored to the individual patient’s SCI level and specific surgical requirements.
Introduction
A comprehensive medical history and anesthesia-directed physical examination are essential for all patients undergoing anesthesia, with a particular focus on systemic complications related to SCI. Chronic complications of SCI, such as autonomic dysreflexia (AD), cardiovascular issues, pulmonary complications, musculoskeletal challenges, and others, must be carefully considered during anesthesia management. This article outlines the key aspects of anesthesia management for patients with SCI.
Cardiovascular Complications
Patients with SCI are at an increased risk of cardiovascular complications during surgery, making preoperative assessment and planning crucial.
| Complication | Autonomic Dysreflexia |
|---|---|
| Description | An exaggerated sympathetic response to stimuli below the level of SCI, leading to symptoms such as vasoconstriction, hypertension, headache, diaphoresis, brady- or tachycardia. |
| Inciting Stimulus | Distended viscus (usually bladder), constipation, pain from pressure sores, and other stimuli. |
| Preoperative Assessment | Obtain a detailed history of AD episodes, inciting events, prior treatments, and surgical/anesthesia histories. |
Coronary Artery Disease (CAD)
- SCI patients have a higher prevalence of CAD.
- CAD risk is 3-10 times higher in SCI patients compared to the general population.
- Consider preoperative pharmacologic stress testing, especially before major surgery.
Other Cardiovascular Considerations
- Baseline blood pressure (BP) is typically reduced in SCI patients above T6.
- Baseline heart rate (HR) may be as low as 50-60 bpm.
- Approximately 50% of these patients are anemic.
- Adjust anesthetic doses and use vasoactive medications cautiously to avoid hypotension.
- Be mindful of orthostatic hypotension during position changes in surgery.
- Address impaired thermoregulation to prevent hypothermia or hyperthermia.
Pulmonary Complications
Pulmonary complications in SCI patients vary based on the level and completeness of the injury.
| Complication | Description |
|---|---|
| Pulmonary Infection | Increased risk due to impaired cough and difficulty mobilizing lung secretions. |
| Reduced Lung Volumes | Lung volumes may deteriorate over time, leading to quick desaturation during anesthesia induction. |
| Assisted Ventilation | Patients with intact bulbar function may require various assisted ventilation techniques. Plan for perioperative management. |
| Phrenic Nerve Pacing | Consideration for independence from a ventilator in patients with an intact phrenic nerve. |
Musculoskeletal Complications
Contractures and muscle spasms are common after SCI and can complicate positioning for surgery.
Pressure Ulcers
Patients with SCI are at risk for skin breakdown and pressure ulcers, requiring careful preoperative examination, positioning, and padding.
Chronic Pain
Many SCI patients develop chronic pain, affecting anesthesia and postoperative pain management.
Airway Evaluation
Patients who have undergone cervical fusion for spine stabilization may have limited neck motion, necessitating alternative intubation devices.
General Anesthesia
Induction of Anesthesia
Induction of anesthesia in SCI patients may require specific considerations due to their sensitivity to anesthetic agents.
| Induction Considerations | Recommendations |
|---|---|
| Choice of Induction Agents | Select agents based on individual patient factors and airway management plan. |
| Induction Agents for SCI Patients | – Administer a fluid bolus (500 to 1000 mL Ringer’s lactate) before induction. |
| – Reduce the dose of induction agents. | |
| – Consider a vasopressor infusion (e.g., phenylephrine) to prevent hypotension, especially in bradycardic patients. |
Neuromuscular Blocking Agents
Avoid succinylcholine in SCI patients present for longer than 48 hours to prevent severe hyperkalemia.
| Neuromuscular Blocking Agents | Recommendations |
|---|---|
| Avoidance of Succinylcholine | – Choose non-depolarizing neuromuscular blocking agents (NMBAs) or intubation with remifentanil as alternatives. |
| Hyperkalemia Risk | – Succinylcholine can cause life-threatening hyperkalemia in SCI patients after 48 to 72 hours post-injury. |
Airway Management
Patients with limited neck mobility due to cervical spine stabilization may require careful airway management.
| Airway Management | Recommendations |
|---|---|
| Choice of Airway Management Device | Select the device based on the patient’s specific condition and surgical needs. |
| Tracheostomy | Consider a cuffed tracheostomy device or replace it with a flexible cuffed endotracheal tube (ETT) if necessary. |
Maintenance of Anesthesia
Patients with SCI may be more sensitive to anesthetics, necessitating adjustments.
| Maintenance Considerations | Recommendations |
|---|---|
| Sensitivity to Anesthetics | – SCI patients may be more sensitive to vasodilatory and myocardial depressant effects. |
| Processed EEG Monitoring | Useful to guide anesthetic agent dosing. |
| Extubation | Ensure complete reversal of neuromuscular blockade. |
| Ventilatory Support | – Patients with ventilatory compromise may require BIPAP or CPAP for ventilation support. |
| – Optimal respiratory mechanics may be achieved in the supine or slightly-head-up position. |
Regional Anesthesia
Regional anesthesia options, such as spinal or peripheral nerve blocks, are suitable alternatives to general anesthesia for specific surgeries.
| Regional Anesthesia | Considerations |
|---|---|
| Spinal Anesthesia | – Effective in preventing autonomic dysfunction. |
| – Challenging to determine the level of spinal block in patients with high spinal cord lesions. | |
| – Low hypotension risk from spinal anesthesia-induced sympathectomy. | |
| Epidural Anesthesia | – Less suitable than spinal anesthesia for SCI patients due to unreliable sacral anesthesia and patchy block. |
| – May not effectively prevent AD. | |
| – Sensory deficits can complicate interpretation of the epidural test dose. |
Positioning for Surgery
Meticulous attention to detail is essential when positioning SCI patients for surgery to prevent pressure injuries.
Hemodynamic Management
Maintaining hemodynamic stability is crucial for SCI patients, particularly those at risk for cardiovascular complications.
| Hemodynamic Management | Recommendations |
|---|---|
| Goal Blood Pressure | – Maintain mean arterial pressure within 20-25% of baseline to preserve spinal cord and coronary perfusion. |
| Fluid Management | Address hypovolemia and anemia with volume preloading. |
| Vasoactive Medications | Tailor medications to the level of SCI and individual patient needs. |
| Vagal Tone | – Be cautious of increased vagal tone during airway manipulation and tracheal suctioning. |
| – Achieve adequate depth of anesthesia before such procedures. | |
| – Consider pretreatment with a vagolytic medication (e.g., glycopyrrolate) for patients with a history of bradycard |
ia.
Management of Intraoperative Autonomic Dysreflexia
Autonomic dysreflexia (AD) can occur during surgery in patients with spinal cord injury (SCI) and requires prompt recognition and intervention to prevent severe complications. AD is characterized by a sudden sympathetic response to stimuli below the SCI level, resulting in a range of symptoms, including hypertension, dysrhythmias, cutaneous changes, headache, and more. This article outlines the signs and symptoms of AD and provides a comprehensive guide to its management during surgery.
Signs and Symptoms of Intraoperative Autonomic Dysreflexia (Table 1)
| Symptom | Description |
|---|---|
| Sudden Hypertension | Rapid increase in systolic blood pressure (>200 mmHg). |
| Dysrhythmias | May include bradycardia, tachycardia, heart block, and sinus arrest. |
| Cutaneous Changes | Vasoconstriction below the spinal lesion with blanching and vasodilation, flushing, and sweating above the lesion. |
| Headache and Nasal Congestion | Awake patients may complain of headache and nasal congestion. |
| Cardiovascular Effects | Severe AD can lead to myocardial ischemia, myocardial infarction, and acute left heart failure. |
| Neurologic Complications | Intracranial hemorrhage and seizures are possible. |
Management of Intraoperative Autonomic Dysreflexia
1. Remove Inciting Stimulus
- Pause surgery if possible and address the inciting stimulus (e.g., empty the bladder, remove endoscope).
2. Deepen Anesthesia
- For patients under general anesthesia, administer a bolus of propofol or deepen the inhalation agent.
3. Position Head Up
- Tip the operating table head-up to take advantage of orthostatic blood pressure drop.
4. Administer 100% Oxygen
- Increase the fraction of inspired oxygen (FiO2) until AD resolves.
5. Administer a Vasodilator
- Administer a rapid-onset, short-acting vasodilator to prevent hypotension when AD resolves:
- Nicardipine: 0.2 to 0.5 mg IV bolus with a nicardipine infusion (2.5 to 15 mg/hour).
- Nitroglycerin infusion: Start at 5 mcg/minute and titrate as needed (up to 200 to 500 mcg/minute).
- Nitroprusside infusion: For severe hypertension, start at 0.2 to 10 mcg/kg/minute.
- Be cautious with nitrates in patients using sildenafil for erectile dysfunction.
6. Consider Longer-Acting Vasodilators
- Longer-acting vasodilators may be administered cautiously. Hypotension can occur once the AD event resolves. Options include:
- Hydralazine: 5 mg IV every 10 minutes, titrated to effect (up to 20 mg total dose).
- Labetalol: 5 mg every 5 minutes, titrated to effect (up to 50 mg total dose); be cautious with beta blockers.
7. Treat Arrhythmias
- Treat arrhythmias as necessary with beta blockers, anticholinergics, and advanced cardiac life support (ACLS) medications.
8. Treat Myocardial Ischemia
- Treat ST and T-wave changes on electrocardiogram (ECG) as necessary, e.g., with nitroglycerin infusion.
9. Invasive Monitoring
- Consider arterial catheter placement for continuous blood pressure monitoring if AD does not resolve quickly.
In most cases, rapid intervention, a pause in surgery, and deepening anesthesia can quickly resolve AD. However, it is crucial to be aware of potential severe complications such as intracranial hemorrhage, acute heart failure, and even death.
Temperature Control
Patients with SCI are susceptible to temperature fluctuations during surgery. Proper temperature management is essential to prevent hypothermia or hyperthermia.
- Monitor temperature during and after anesthesia.
- Utilize warm air blankets and fluid warming intraoperatively.
- Continue temperature management into the recovery period.
Postoperative Care
The postoperative period is critical for SCI patients, with ongoing monitoring and management of AD and other potential complications.
Extended Recovery Room Stay
Patients with chronic SCI may require an extended recovery room stay to allow for stabilization of blood pressure (BP), breathing, airway control, and temperature. Additionally, the management of postoperative pain is a key consideration.
Ongoing Vasodilator Infusion
If ongoing vasodilator infusion is required, the patient should be transferred to the intensive care unit (ICU) for close monitoring and specialized care.
Autonomic Dysreflexia in the Postoperative Period
AD may occur in the postoperative period, often related to bladder distention. The principles for managing postoperative AD are similar to those during surgery.
Multimodal Pain Management
The plan for postoperative pain control must be individualized and is influenced by the surgical procedure, the level of sensory impairment, and preoperative chronic opioid use. In many cases, a multimodal approach to pain management, combining opioids with non-opioid analgesics, may be appropriate to achieve effective pain control while minimizing side effects.
This comprehensive guide outlines the critical considerations for anesthesia management in patients with spinal cord injury. Careful assessment, individualization of care, and close monitoring are paramount to ensuring the safety and well-being of these patients throughout the surgical and postoperative phases. Always consult with healthcare professionals experienced in SCI management for specific patient care.
