Anesthesia for adults with acute spinal cord injury

INTRODUCTION — Spinal cord injury (SCI) is a common, often devastating event, with approximately 17,730 new cases in the United States each year [1].

This topic will discuss anesthetic management in the operating room (OR) for adults with acute SCI. Diagnosis, emergency department (ED) management, medical therapy, and anesthesia for patients with chronic SCI are discussed separately.

●(See "Cervical spinal column injuries in adults: Evaluation and initial management".)

●(See "Acute traumatic spinal cord injury".)

●(See "Anesthesia for adults with chronic spinal cord injury".)

For the purpose of this discussion, the acute period will be defined as the first several weeks after the injury.

SYSTEMIC EFFECTS OF ACUTE SPINAL CORD INJURY — In addition to neurologic injury, cervical and upper thoracic acute spinal cord injuries (ASCIs) are associated with cardiovascular and pulmonary complications that affect the plan for anesthetic management.

Spinal shock — Spinal shock and neurogenic shock are two distinct entities:

●Spinal shock refers to the altered physiologic state that can occur immediately after a spinal cord injury (SCI), manifested by loss of spinal cord function caudal to the level of the injury, with flaccid paralysis, anesthesia, absent bowel and bladder control, and loss of reflex activity [2,3]. Spinal shock can last days to weeks after SCI [2].

●Neurogenic shock is part of the spinal shock syndrome and refers to the hemodynamic state, which includes hypotension, bradycardia, and hypothermia, as a result of loss of sympathetic tone after SCI [2].

Cardiovascular complications — ASCI can produce a number of cardiovascular complications including hypotension, bradycardia and other arrhythmias, and early autonomic dysreflexia. Therefore, patients presenting for anesthesia may be in an unstable hemodynamic condition. In addition, patients with SCI may have other traumatic injuries; when appropriate, hemorrhagic shock, cardiac tamponade, and pneumothorax should be ruled out as causes for hypotension.

●Neurogenic shock – Clinical manifestations of neurogenic shock include hypotension, bradycardia, and hypothermia. SCI that disrupts descending sympathetic pathways results in altered regulation of autonomic cardiovascular function. The predominance of parasympathetic influence causes neurogenic shock, with hypotension and bradycardia [4]. Impaired sympathetic tone reduces vascular resistance in large vascular beds (ie, skeletal muscles and splanchnic vessels), resulting in increased venous capacitance, decreased venous return to the heart, and hypotension. In addition, disruption of cardiac sympathetic influences can leave vagal tone from higher centers unopposed, resulting in bradycardia, bradyarrhythmias, and heart block. Neurogenic shock develops within 30 minutes following injury and may last up to six weeks [5]. Orthostatic hypotension can be severe early after injury, even in patients with SCI below T6, with loss of reflex vasoconstriction in skeletal muscle beds [6].

Neurogenic shock is more common with complete cervical spine injury (19 to 29 percent) than with thoracolumbar and incomplete cervical injury [5,7-9].

Maintenance of blood pressure (BP) is critical, as hypotension may result in spinal cord hypoperfusion and exacerbate secondary injury to the spinal cord. (See "Acute traumatic spinal cord injury", section on 'Cardiovascular complications' and 'Hemodynamic management' below.)

●Arrhythmias – Bradycardia is the most common heart rate (HR) abnormality seen after SCI and may require treatment with atropine or pacing [8]; heart block, supraventricular tachycardia, ventricular tachycardia, and cardiac arrest have also been reported [7]. Almost all patients with complete cervical SCI will have a resting HR <60 beats/minute (bpm), and approximately 70 percent will have a HR <45 bpm [7]. Bradyarrhythmias peak on day 4 after injury, and other hemodynamic abnormalities typically resolve over two to six weeks.

●Autonomic dysreflexia – Autonomic dysreflexia is a constellation of signs and symptoms of excess sympathetic activity in response to a stimulus below the level of a spinal injury of T6 or higher. It is usually defined as an increase in systolic BP (SBP) of >20 percent, often accompanied by bradycardia or arrhythmias, flushing, sweating, headache, blurred vision, and nasal congestion [10]. Autonomic dysreflexia is more common in the chronic phase after injury, but it can occur in the acute phase as well [10-12]. Patients with severe cervical SCI are at particular risk, with episodes related to somatic pain, abdominal distention, fecal impaction, and bladder distention.

Autonomic dysreflexia should be treated immediately with removal of the stimulus and, if necessary, vasodilating medication in order to prevent complications of severe hypertension. (See "Chronic complications of spinal cord injury and disease", section on 'Autonomic dysreflexia' and "Anesthesia for adults with chronic spinal cord injury", section on 'Management of intraoperative autonomic dysreflexia'.)

●Deep vein thrombosis – Deep venous thrombosis (DVT) is a common complication of ASCI, and patients are typically treated with antithrombotic therapy and pneumatic compression devices. (See "Acute traumatic spinal cord injury", section on 'Venous thromboembolism and pulmonary embolism'.)

Pulmonary complications — Pulmonary complications including ventilatory failure, pneumonia, atelectasis, mucous plugging, pulmonary edema, and pulmonary embolism constitute the most frequent category of complications during acute hospitalization after traumatic SCI and contribute substantively to early morbidity and mortality [13-17]. The respiratory complications following SCI vary depending on the level and completeness of injury and preexisting respiratory status.

High cervical injuries affect the diaphragm and accessory muscles of respiration. Respiratory complications have been reported in 80 percent of patients with injuries above C4 and 60 percent of patients with C5 to C8 injury. Those with complete lesions have a flaccid chest wall, often accompanied by hypoxia and hypoventilation, and usually require immediate endotracheal intubation and mechanical ventilation. Patients with complete mid- to lower-cervical lesions may initially oxygenate and ventilate adequately but often progress to respiratory failure, with the peak time for ventilatory failure at 3 to 4.5 days [18,19].

The sympathectomy associated with injuries above T6 can result in bronchospasm and increased pulmonary secretions, which, when combined with the inability to produce an effective cough, lead to significant mucous plugging, obstruction of bronchioles, pneumonia, increased work of breathing, and ventilator failure.

Respiratory complications in patients with thoracic SCIs are often related to direct chest trauma (eg, traumatic pneumothorax, flail chest from rib fractures, rupture of the diaphragm or a bronchus, pulmonary contusions or lacerations, or hemopericardium). A high index of suspicion for such injuries should be maintained for patients with thoracic vertebral injuries [19].

Respiratory complications following SCI, as well as their management, are discussed in detail separately. (See "Respiratory complications in the adult patient with chronic spinal cord injury".)

Other medical complications — A number of other medical complications of SCI are of particular concern to the anesthesiologist, including the following (see "Acute traumatic spinal cord injury", section on 'Other medical complications'):

●Gastrointestinal complications – Patients with ASCI should be considered at high risk of aspiration on induction of anesthesia. In the acute phase of SCI above the midthoracic level, gastric dilatation with delayed gastric emptying [20], paralytic ileus [21], acute gastroduodenal ulceration and hemorrhage [22], and acute acalculous cholecystitis [23] can all occur as part of spinal shock.

●Electrolyte disorders – Electrolyte abnormalities have been associated with ASCI. Hyponatremia is common and may relate to disruption of the renal sympathetic pathways that regulate the renin–angiotensin response [24]. Glucose tolerance may be impaired by the stress response or because of administration of glucocorticoids, especially in patients with preexisting diabetes [25].

●Urologic complications – Patients with SCI are at risk for urinary retention, bladder distension injury, and autonomic dysreflexia, and require bladder catheterization in the acute phase of the injury. A distended bladder is a common stimulus for autonomic dysreflexia. During surgery, the catheter output should be monitored for kinking to avoid bladder distention.

●Temperature control – The sympathectomy associated with high SCI can cause vasodilation and heat loss below the level of injury. Patients with neurogenic shock are frequently warm to the touch but hypothermic centrally [26]. Core temperature should be monitored closely during anesthesia, with in-line fluid warmers and forced-air warming blankets used as necessary. Hyperthermia should be avoided, particularly in patients with associated traumatic brain injury (TBI).

Timing of surgery — The ideal timing for surgical decompression following traumatic spinal cord injury is controversial. The decisions to operate and the timing of surgery are typically made by the surgeon in consultation with other specialists caring for the patient, and may be different for patients with complete versus incomplete traumatic injury. In some cases, these decisions must balance the possibility of improved surgical outcome against the need to optimize hemodynamics or correct other physiologic derangements, particularly in patients with multi trauma. Timing of surgery after acute traumatic spinal cord injury is discussed separately. (See "Acute traumatic spinal cord injury", section on 'Timing'.)

PREOPERATIVE EVALUATION — Preanesthesia evaluation should be as thorough as the urgency of the situation allows. When possible, the full extent of the patient's injuries, course since injury, and medical history should be reviewed, and an airway assessment and directed physical examination should be performed.

Other injuries often occur at the time of spinal cord injury (SCI). Facial fractures, TBI, thoracoabdominal trauma, and bony fractures are common and can affect anesthetic management [27]. As an example, patients with significantly elevated intracranial pressure (ICP) from an associated TBI may not tolerate prone positioning for instrumentation of spinal fractures until cerebral edema has been treated or has subsided. Similarly, patients who develop severe acute lung injury will also require special perioperative management. In many cases, the anesthesiologist, surgeon, and intensivist must discuss the relative risks and benefits related to the timing of surgery.

Airway evaluation — In all but the most urgent situations, an airway evaluation should be performed, including assessment of mouth opening, dentition, presence of other facial injuries, head trauma, blood in the airway, and the patient's level of cooperation. Until the cervical spine has been appropriately imaged to rule out an injury in a trauma patient, the anesthesiologist should assume that it is unstable. When possible, spinal imaging should be reviewed.

The patient may present with the cervical spine immobilized with a halo, a collar, or other devices that may affect the ability to mask ventilate or instrument the airway.

ANESTHETIC MANAGEMENT — Anesthesiologists can be involved in initial airway management for patients with acute spinal cord injury (ASCI), in resuscitation in the intensive care unit (ICU), and in the operating room (OR) for spinal or other surgical procedures.

Choice of anesthetic technique — In most cases, patients with SCI will require general anesthesia for surgical procedures. For very peripheral procedures (eg, closed reduction of distal extremity fractures, closure of superficial extremity wounds), peripheral nerve block can be utilized if it can be performed without moving the spine and is not otherwise contraindicated.

Monitoring — Standard monitors (blood pressure [BP] monitoring, pulse oximetry, electrocardiogram [ECG], end-tidal carbon dioxide [ETCO₂], oxygen [O₂] analysis, and temperature) are used for all patients having general anesthesia. In addition, patients with high thoracic and cervical spine injuries should usually have BP monitored continually with an intraarterial catheter, which should be placed before induction of anesthesia to allow immediate response to changes in hemodynamics. (See 'Induction of anesthesia' below.)

In addition to continuous BP monitoring, arterial catheterization facilitates serial blood sampling for laboratory evaluation of hematocrit, coagulation parameters, electrolytes, blood gases, and serum lactate level. Pulse pressure variation of the arterial trace can provide a measure of the patient's volume status [28]. (See "Intraoperative fluid management", section on 'Dynamic parameters to assess volume responsiveness'.)

When neuromonitoring is used during spine surgery, the choice of anesthetic agents must be modified to allow optimal monitoring. (See "Neuromonitoring in surgery and anesthesia".)

Venous access — Adequate venous access should be obtained before positioning the patient for surgery. Spine surgery may result in massive blood loss; we place two large-bore intravenous (IV) catheters (if possible, 14- or 16-gauge) for multilevel fusion and instrumentation. We use a fluid warmer in the line connected to the largest IV. (See 'Temperature management' below.)

Central venous catheterization may be indicated when necessary for adequate access, and for administration of vasoactive drugs.

Premedication — Administration of anxiolytic and opioid medications should be done cautiously in ASCI patients as they may have associated TBI, pulmonary contusions, or other conditions that may predispose them to inadequate ventilation and oxygenation. The clinical circumstance and associated injuries should guide the choice of these medications administered immediately prior to surgery. Premedication should be administered in small doses or not at all, titrated to effect (eg, midazolam 1 to 2 mg IV in divided doses).

Preoxygenation — Patients should be preoxygenated prior to induction of anesthesia. While a head-up position is often beneficial, particularly for patients at risk for aspiration, patients with high SCI may become hypotensive when placed head-up. If airway management is anticipated to be difficult, and facemask preoxygenation also deemed difficult (eg, patients with facial fractures)or ineffective, administration of O₂ via nasal cannulae during airway manipulation may delay oxygen desaturation [29-31]. (See "Preoxygenation and apneic oxygenation for airway management for anesthesia".)

Induction of anesthesia — Induction of anesthesia with IV medication is appropriate for most adults who require general anesthesia. Rarely, induction is performed with inhalation of a volatile anesthetic. Choices of induction agents relate to the plan for airway management, as well as other patient factors. Rapid sequence induction and intubation (RSII) is often indicated for patients with ASCI, though the technique may require modification when difficult airway management is anticipated. (See "Rapid sequence induction and intubation (RSII) for anesthesia" and "Management of the difficult airway for general anesthesia in adults", section on 'Airway Approach Algorithm'.)

For patients with acute cervical SCI, we do not routinely apply cricoid pressure during RSII, to avoid cervical spine motion. (See 'Cervical spine motion and success during airway management' below.)

●Induction agents – The most common IV anesthesia induction agents are propofol, ketamine, and etomidate. Outside the United States, sodium pentothal may be used. These agents are discussed more fully separately. (See "General anesthesia: Intravenous induction agents".)

Patients with thoracic and cervical ASCI are at high risk for hypotension with induction of anesthesia, a result of direct effects of induction agents, hypovolemia, and sympathetic denervation. Doses of induction agents should be reduced for these patients, and hypotension should be avoided to prevent secondary injury to the spinal cord. (See "General anesthesia: Intravenous induction agents", section on 'Dosing considerations'.)

We connect a vasopressor infusion to the IV line and often start a low dose (eg, phenylephrine 20 to 40 mcg/minute) prior to or with induction as prophylaxis for hypotension if the patient is not bradycardic, as phenylephrine usually causes reflex bradycardia. For bradycardic patients, we often administer ephedrine 5 to 15 mg or glycopyrrolate 0.2 to 0.4 mg IV with or without phenylephrine to prevent hypotension. (See 'Hemodynamic management' below.)

●Neuromuscular blocking agents (NMBAs) – Succinylcholine is a rapidly acting depolarizing NMBA used for endotracheal intubation. It causes a transient increase in serum potassium level of approximately 0.5 mEq/L in normal patients but can cause life-threatening, severe hyperkalemia in patients with SCI after 48 to 72 hours postinjury [32]. We avoid succinylcholine after 48 hours after SCI.

Alternatives to succinylcholine include nondepolarizing NMBAs and intubation with remifentanil. The choice of NMBA may be affected by neuromonitoring for spine surgery. If neuromonitoring is planned, rocuronium can be used for intubation and rapidly reversed with sugammadex to allow monitoring soon after intubation and/or patient positioning. One randomized trial confirmed that in addition to reversing paralysis, sugammadex allows neuromuscular monitoring. In this trial including 66 patients who had spine surgery with transcranial motor evoked potential monitoring, reversal of rocuronium with sugammadex increased the train of four ratio, and simultaneously increased the motor evoked potentials (MEP) amplitude [33].

Although infrequent, patients should be monitored closely for symptoms of anaphylaxis and cardiac arrhythmias including profound bradycardia if sugammadex is administered. (See "Rapid sequence induction and intubation (RSII) for anesthesia", section on 'Neuromuscular blocking agents (NMBAs)' and "Neuromonitoring in surgery and anesthesia", section on 'Neuromuscular blocking agents' and "Clinical use of neuromuscular blocking agents in anesthesia", section on 'Sugammadex'.)

●Anticholinergic medication – Patients with high thoracic and cervical spine injuries, especially those with neurogenic shock and preoperative bradycardia, are at high risk for severe bradycardia and even cardiac arrest with airway manipulation [34,35]. Anticholinergic medication (ie, atropine 0.4 mg IV, glycopyrrolate 0.2 to 0.4 mg IV) should be administered prior to induction of anesthesia for these high-risk patients with preoperative bradycardia.

Airway management — For patients with cervical and high thoracic SCI, movement of the cervical spine must be avoided during airway management to avoid further injury of the spinal cord. No technique for airway management has been shown to be superior to others for prevention of neurologic deterioration in the patient with an unstable cervical spine [36,37]. The technique chosen should reflect the clinical circumstance, patient factors, and the expertise of the clinician. The use of some form of spine immobilization during airway maneuvers has become a standard of care. (See "Cervical spinal column injuries in adults: Evaluation and initial management", section on 'Airway management'.)

Airway management may be difficult in patients with cervical spine injury because of limited neck extension, associated facial or head injuries, retropharyngeal hemorrhage or edema, and the presence of cervical spine stabilization devices. As always, experienced personnel and equipment for difficult airway management should be immediately available. (See "Airway management for induction of general anesthesia", section on 'Prediction of the difficult airway' and "Management of the difficult airway for general anesthesia in adults".)

Airway management strategy — Our strategy for airway management for patients with SCI, without considerations required for other injuries, is as follows:

●We use manual in-line stabilization (MILS) during all aspects of airway management for patients with cervical or high thoracic ASCI. (See 'Manual in-line stabilization (MILS)' below.)

●We avoid succinylcholine after 48 hours after injury. (See 'Induction of anesthesia' above.)

●If mask ventilation is required for patients with cervical or high thoracic SCI, when necessary, we insert an oral or nasal airway using outward jaw thrust without neck extension to improve ventilation while minimizing cervical spine movement. (See 'Cervical spine motion and success during airway management' below.)

●For emergency procedures without anticipated difficulty with airway management, we use the following approach:

•For patients with low thoracic or lumbar SCI, we perform RSII with direct or indirect laryngoscopy (eg, video laryngoscopy [VL]) depending on patient factors.

•For patients with cervical or high thoracic injury, we perform RSII with VL to minimize neck extension, though flexible scope intubation (FSI) or direct laryngoscopy with MILS are reasonable alternatives for experienced clinicians in this setting.

The use of cricoid pressure for RSII is controversial, including for patients with cervical spine injury. We avoid cricoid pressure for patients with cervical spine injury, using a gentle backward-upward-rightward pressure (BURP) maneuver if necessary to improve laryngoscopic view. Caution should be used with cricoid pressure with lower cervical spine injury, as it has been shown to increase distraction, angulation, and translation in an unstable C5 to C6 cadaveric model [38]. (See 'Cervical spine motion and success during airway management' below.)

●For nonemergency procedures, we perform RSII as indicated by the patient's clinical condition and airway assessment. (See "Airway management for induction of general anesthesia", section on 'Airway assessment' and "Airway management for induction of general anesthesia", section on 'Prediction of the difficult airway' and "Airway management for induction of general anesthesia", section on 'Creation of a strategy for airway management'.)

•When RSII is not required, for patients with low thoracic or lumbar SCI, we perform direct or indirect laryngoscopy.

•For patients with cervical or high thoracic SCI, we intubate with a video laryngoscope or flexible scope to minimize spine motion.

●Our decision to intubate awake or asleep depends on the level of patient cooperation, and the expected degree of difficulty with all aspects of airway management. If awake intubation is required, we intubate with a flexible scope. (See "Management of the difficult airway for general anesthesia in adults", section on 'Awake intubation' and "Management of the difficult airway for general anesthesia in adults", section on 'Airway Approach Algorithm' and 'Awake versus asleep intubation' below.)

●For patients with facial trauma or other features predicting difficult intubation, we prepare for a surgical airway, with necessary personnel and equipment immediately available. (See "Management of the difficult airway for general anesthesia in adults", section on 'Surgical airway'.)

Manual in-line stabilization (MILS) — We suggest the use of MILS during airway management for patients with cervical ASCI or high thoracic ASCI, unless the patient presents with a halo apparatus in place. Cervical spine motion during airway maneuvers is reduced but not eliminated by MILS [39].

For MILS, an assistant grasps the mastoid process with the fingertips, with the occiput in the palms of the hands, standing at the head of the operating table beside the intubating clinician. Alternatively, the assistant may stand at the patient's shoulder, holding the mastoid with the palms, and the occiput with the fingertips. Either way, the assistant should apply enough force to counter forces applied during laryngoscopy to keep the head and neck in a neutral position, without applying traction. Unopposed traction during MILS carries risk of excess spinal distraction and should be avoided (figure 1) [40-42].

When a hard collar is in place for preoperative spine immobilization, MILS should be established, and then the front of the collar may be removed if more space is needed for adequate mouth opening. Once the airway is secured, the collar can be replaced.

MILS may prolong the time to intubation by worsening the view of the glottis; indirect laryngoscopy with a video laryngoscope or flexible scope, or alternative airway management strategies may be required. A prospective randomized study of 200 elective surgical patients without SCI compared endotracheal intubation with and without MILS [43]. MILS increased the rate of failed intubation at 30 seconds (50 percent with MILS versus 5.7 percent without MILS). All patients who failed intubation in the MILS group were successfully intubated when MILS was released. The application of cricoid pressure or use of a gum elastic bougie may improve the rate of successful intubation with MILS [44]. However, caution should be used with cricoid pressure with lower cervical injuries as it has been shown to increase distraction, angulation, and translation in an unstable C5 to C6 cadaveric model [38]. (See 'Cervical spine motion and success during airway management' below.)

Choice of airway device — Most patients with SCI are at high risk of aspiration with induction of anesthesia and therefore require endotracheal intubation for general anesthesia. The decision to intubate awake or asleep, the decision to perform an RSII, and the choice of intubation technique depend on the urgency of the clinical situation, the level of SCI, anticipated difficulty with airway management, availability of equipment, and clinician expertise. (See "Airway management for induction of general anesthesia", section on 'Creation of a strategy for airway management' and "Rapid sequence induction and intubation (RSII) for anesthesia" and "Management of the difficult airway for general anesthesia in adults", section on 'Planning the anesthetic approach'.)

Awake versus asleep intubation — Awake endotracheal intubation is an option for cooperative patients with ASCI. Blind nasal intubation can be performed, but for general anesthesia, FSI is the most commonly used awake technique [13]. Retrospective reviews have reported no difference in neurologic outcome with asleep versus awake intubation for patients with cervical ASCI [36,45]. The choice between awake and asleep intubation should be individualized based on the clinical situation, the patient's level of cooperation, the expected difficulty with airway management, and clinician expertise. (See "Management of the difficult airway for general anesthesia in adults", section on 'Planning the anesthetic approach'.)

Advantages of awake intubation for patients with cervical ASCI include:

●The head and neck can be left in a neutral position, with little or no motion during airway management.

●Spontaneous ventilation is maintained until the airway is secured, which is of particular value for patients in with anticipated difficult airway management.

●Neurologic evaluation can be performed after airway management.

Disadvantages to awake intubation include:

●In most cases, awake intubation takes longer than asleep intubation.

●Even with airway topicalization, coughing and gagging may occur during awake intubation, with potential for movement of the injured spine.

●Presence of blood, secretions, or vomitus in the airway and distortion of anatomy by trauma can make FSI difficult or impossible.

●Sedation is often required for smooth awake intubation, which may reduce the likelihood of useful neurologic assessment after intubation or positioning.

●FSI requires specific expertise, especially for difficult intubations. (See "Flexible scope intubation for anesthesia".)

Cervical spine motion and success during airway management — All airway maneuvers are associated with some degree of cervical spine movement [46]. In general, the degree of movement during careful airway management is small when compared with normal physiologic motion, but the implications of even small movements for patients with SCI are unclear. Neurologic deterioration after careful airway management in patients with ASCI appears to be very rare, but this conclusion is based on retrospective reviews and accumulated clinical experience, rather than prospective randomized trials [36,45,47-51].

For emergency procedures in patients with cervical or high thoracic SCI without anticipated difficulty with airway management, we perform RSII with a video laryngoscope to minimize spine motion, and avoid cricoid pressure. If mask ventilation is required in these patients, when necessary, we insert an oral or nasal airway using outward jaw thrust without neck extension to improve ventilation while minimizing cervical spine movement.

The degree of cervical spine motion associated with airway management maneuvers has been studied in human volunteers and cadavers.

●Mask ventilation – Mask ventilation can cause significant cervical spine movement. Therefore, we apply MILS with induction of anesthesia and throughout airway manipulation and, if necessary, place an oral airway with jaw thrust, but without chin lift/extension of the neck, to improve ventilation [52].

In cadaver studies with destabilized cervical spines, chin lift and jaw thrust were found to result in more cervical spine displacement and increase in disc space than either oral or nasal intubation [53,54], but jaw thrust without chin lift/neck extension resulted in significantly less displacement [52].

●Supraglottic airway (SGA) placement – SGA devices can cause cervical spine motion and exert pressure on the cervical spine during insertion, inflation, and removal [14,55], though the clinical relevance of these effects in patients with SCI is undetermined.

SGAs are not usually used as primary airway devices in patients with ASCI because of full stomach concerns, but we do not hesitate to use SGAs in these patients as part of difficult or failed airway management. (See "Supraglottic devices (including laryngeal mask airways) for airway management for anesthesia in adults", section on 'Supraglottic airways and the difficult airway'.)

●Cricoid pressure – We do not routinely use cricoid pressure during RSII for patients with acute cervical SCI; we use gentle BURP only if necessary to improve the view during laryngoscopy.

Cricoid pressure may be used during airway management as part of the RSII technique to prevent passive regurgitation of stomach contents or to improve the view of the glottis during direct laryngoscopy. The use of cricoid pressure in patients with ASCI is controversial for two reasons:

•Forceful pressure over the site of a cervical spine fracture may result in as much motion as direct laryngoscopy. A cadaver destabilized spine study found that cricoid pressure caused distraction, angulation, and translation of the injured spine [38].

And

•Efficacy of cricoid pressure for prevention of regurgitation has been questioned. (See "Rapid sequence induction and intubation (RSII) for anesthesia", section on 'Cricoid pressure controversies'.)

●Direct laryngoscopy – Direct laryngoscopy has been shown to move the cervical spine in patients without SCI and in cadavers with destabilizing spine injury [53,54,56,57]. However, the clinical significance of this degree of motion in patients with SCI is unknown.

The type of laryngoscope blade employed does not appear to significantly affect movement of the spine. Studies of patients without spinal pathology [58,59] and of fresh cadavers with destabilizing injury [15] have found no difference in the degree of spinal movement with the use of Macintosh or Miller blades, the most commonly used laryngoscope blades.

●Indirect laryngoscopy – The use of VL (eg, C-MAC, Airtraq, GlideScope, McGrath, or Bullard) allows endotracheal intubation without the need for a direct line of sight to the glottis. When used for intubation with MILS, these devices have been shown to improve the view of the glottis and usually (though not always) reduce the degree of cervical spine motion compared with direct laryngoscopy [14,16,17,58,60,61]. Importantly, spine motion occurs with VL and the safe degree of motion is unknown.

In one trial, 60 patients without SCI who were intubated for surgery were randomly assigned to direct laryngoscopy (DL) with a Macintosh blade versus VL with a Glidescope, both without MILS [62]. The median angle deviation of the neck was 11.8 degrees with VL, compared with 14.3 degrees with DL. Maximum angle deviations were 19.2 and 29.3 degrees with VL versus DL, respectively. Increased experience with Glidescope intubation was associated with decreased median total neck motion.

Video laryngoscopy may improve intubation success in patient with difficult direct laryngoscopy. Most studies comparing video laryngoscope with direct laryngoscope in a wide range of patient populations have reported similar numbers of intubation attempts, respiratory complications, and time to intubation. (See "Video laryngoscopes and optical stylets for airway management for anesthesia in adults", section on 'VL versus DL'.)

A 2021 network meta-analysis of 80 randomized trials (8039 patients) that evaluated the use of a variety of intubating devices in patients with various methods of cervical spine immobilization (eg, MILS, cervical collar, other alternatives) found that the McGrath, Airtraq, King Vision, C-MAC; and Glidescope with a tube guide, all increased first pass success compared with a standard Macintosh laryngoscope blade [63]. Only the Airway Scope increased first pass success in patients who had MILS, versus other methods of immobilization. (See "Video laryngoscopes and optical stylets for airway management for anesthesia in adults", section on 'Channeled VL'.)

The increase in use of video laryngoscopes for intubation during anesthesia has significantly reduced the use of FSI for patients with unstable cervical spines [37]. Video laryngoscopy may increase first pass success and decrease the time to intubation compared with FSI.

•In a randomized trial including 330 patients undergoing cervical spine surgery who had a cervical collar in place during induction of anesthesia, video laryngoscopy improved first attempt success (98.8 percent versus 90.9 percent) and reduced time to intubation (median 50 versus 81 seconds) compared with FSI [64].

•In another trial of 140 patients who had manual in line stabilization during intubation attempts and were randomly assigned to the use of a C-MAC video laryngoscope versus a flexible scope for intubation, first attempt success was similar in the two groups (82.8 with C-MAC versus 78.5 percent with flexible scope), and time to intubation was faster with the C-MAC (35 ± 22 versus 59 ± 36 seconds) [65].

●Flexible scope intubation – Flexible scope intubation, either asleep or awake, causes little motion of the cervical spine [66]. However, coughing or gagging can occur during topicalization for awake intubation or during intubation if not adequately topically anesthetized, resulting in motion of the injured spine. In fact, FSI in an emergency situation with providers who are inexperienced with this device has a high failure rate [67] and can be very challenging if the patient is uncooperative or with blood or emesis in the airway. (See "Awake tracheal intubation".)

Maintenance of anesthesia — Choice of medications for maintenance of anesthesia depends on patient factors, the planned procedure, and, if applicable, intraoperative neuromonitoring. When neuromonitoring is used during spine surgery, the choice of anesthetic agents must be modified to allow optimal monitoring. (See "Maintenance of general anesthesia: Overview" and "Neuromonitoring in surgery and anesthesia", section on 'Maintenance of anesthesia'.)

Hemodynamic management — Acute spinal cord injury (ASCI) is often associated with hypotension as a result of sympathetic denervation, hypovolemia caused by associated injuries, or both. Blood pressure (BP) should be carefully managed in these patients to preserve spinal cord perfusion and to prevent secondary spinal cord injury (SCI). Spinal cord perfusion is dependent on mean arterial pressure (MAP) and is autoregulated over a wide range of systemic BP [68,69]. Autoregulation may be lost after SCI, rendering the cord more susceptible to ischemia with hypotension [68].

Prospective controlled data to guide specific recommendations for goal BP after SCI are lacking. Standards and guidelines are therefore based on animal studies, case series, and expert opinion [70-73]. The American Association of Neurological Surgeons guidelines for BP management include maintenance of a MAP of 85 to 90 mmHg for five to seven days after acute cervical SCI and avoidance of a systolic BP (SBP) below 90 mmHg, both as level 3 (optional) recommendations [74]. BP control may require administration of intravenous (IV) fluid and blood products, vasopressors, and inotropes.

●Fluid management – All patients with ASCI with a significant sympathectomy require initial volume resuscitation starting with IV crystalloid, with addition of colloid and blood products as necessary. In patients with traumatic brain injury, which is common in patients with ASCI, albumin should be used with caution. This concern is discussed separately. (See "Anesthesia for patients with acute traumatic brain injury", section on 'Intraoperative fluid management'.)

Volume overload should be avoided in order to prevent pulmonary and spinal cord edema, though optimal clinical endpoints for volume resuscitation have not been established. Acid–base status, lactate levels, estimated blood loss, and urine output should be utilized to guide fluid resuscitation [75].

Pulse pressure variation (PPV) of the arterial trace and stroke volume variation provide a measure of the patient's volume status during positive pressure mechanical ventilation and can help guide fluid administration [28]. During mechanical ventilation in the supine position, PPV >11 to 13 percent predicts that the patient will respond to a fluid challenge with an increase in cardiac output. (See "Intraoperative fluid management", section on 'Respiratory variations in arterial pressure waveform'.)

In the prone position, trends in PPV, rather than the absolute number, along with other indicators of volume status should be used to guide fluid management. In the prone position, the threshold PPV that predicts volume responsiveness is higher than the threshold PPV in the supine position [76]. In a study of 30 patients who underwent prone spine surgery, PPV predictive of fluid responsiveness was higher in the prone position compared with the supine position (PPV >15 percent versus >11 percent). However, variability in intraabdominal and intrathoracic pressures in the prone position alters venous return and prevents identification of an absolute threshold PPV for volume responsiveness for all prone patients.

Assessment of intraoperative volume status and choice of intraoperative fluids are discussed more fully separately. (See "Intraoperative fluid management", section on 'Monitoring intravascular volume status' and "Intraoperative fluid management", section on 'Choosing fluid: Crystalloid, colloid, or blood'.)

●Antifibrinolytics – The perioperative use of antifibrinolytics (ie, tranexamic acid, epsilon aminocaproic acid, or outside the US aprotinin) has been shown to significantly reduce blood loss and red blood cell transfusion in various surgical procedures, including spine surgery (see "Anesthesia for elective spine surgery in adults", section on 'Antifibrinolytics'). Several studies have reported no increased risk of major thromboembolic complications (ie, stroke, deep vein thrombosis, or pulmonary embolism) in healthy patients who receive perioperative antifibrinolytics. However, the safety of these drugs in patients at high baseline risk of thromboembolic events is less certain, and many experts avoid antifibrinolytics in patients with a history of venous or arterial thromboembolism. (See "Anesthesia for total knee arthroplasty", section on 'Thrombotic complications'.)

Therefore, in patients with acute trauma, caution should be exercised when considering the use of antifibrinolytics if the patient's full medical history is unavailable. In addition to thromboembolic risks, there is a dose-related risk of seizures after administration of tranexamic acid, and doses should be reduced for patients with renal dysfunction, lower body weight, or malnutrition. (See "Anesthesia for total knee arthroplasty", section on 'Seizures'.)

●Postoperative visual loss (POVL) – While not a direct effect of SCI itself, patients with SCI who undergo spinal stabilization and other prolonged surgery in the prone position are at increased risk for POVL. Recommendations for fluid management in this setting include the administration of colloids and crystalloid, as well as the frequent measurement of hemoglobin during surgery. Strategies for anesthetic management for patients at risk for POVL are discussed separately. (See "Postoperative visual loss after anesthesia for nonocular surgery", section on 'Strategies for prone spine surgery'.)

●Intraoperative transfusion – The optimal hematocrit for patients with SCI has not been established. In general, as for other acutely ill patients, we aim for a hematocrit of 21 to 30 percent. The threshold for intraoperative transfusion depends on multiple factors, including the patient's age, presence of acute lung injury, coronary artery or cerebrovascular disease, and ongoing blood loss. The target threshold transfusion trigger should be made on a case-by-case basis with consideration of the rate and quantity of expected blood loss, the patient's coexisting illnesses, and the potential for postoperative bleeding into surgical drains. Setting a threshold means that a hematocrit lower than the threshold will have to occur before transfusion is triggered. (See "Indications and hemoglobin thresholds for RBC transfusion in adults".)

●Vasoactive medications – In addition to volume resuscitation, vasoactive medications are required for most patients with SCI. With injury above the cardioaccelerator sympathetic innervation (T1 to T4), vasopressors with inotropic and chronotropic properties in addition to vasoconstriction (ie, dopamine, norepinephrine, epinephrine) are often required. Norepinephrine may slightly improve spinal cord perfusion in these patients, compared with dopamine. In a prospective crossover study including 11 patients with cervical and thoracic SCI, norepinephrine was able to maintain MAP with a lower intrathecal pressure (17 mmHg versus 20 mmHg), and a correspondingly slightly higher spinal cord perfusion pressure (67 mmHg versus 65 mmHg), compared with dopamine [77]. Neurologic recovery was not assessed.

With lower spinal injuries, peripheral sympathectomy and vasodilation often require treatment with a pure vasoconstrictor once euvolemia is achieved (eg, phenylephrine). (See "Use of vasopressors and inotropes".)

Temperature management — Temperature control is impaired in patients with ASCI and is further reduced by general anesthesia. Core temperature should be monitored throughout the anesthetic. Fluid warmers and forced-air warming or cooling blankets should be used as necessary. (See "Perioperative temperature management".)

Hyperthermia should be avoided, particularly in patients with associated acute traumatic brain injury (TBI). (See "Anesthesia for patients with acute traumatic brain injury" and "Management of acute moderate and severe traumatic brain injury", section on 'Temperature management'.)

Emergence from anesthesia — Many patients with ASCI come to the operating room (OR) from the intensive care unit (ICU) and go back to the ICU after surgery.

Patients with severe cervical SCI are most often left intubated at the end of surgical procedures, with the expectation that they will require assisted ventilation and possibly tracheostomy in the acute period after injury.

The decision to extubate patients with partial and lower SCI depends on associated injuries, the length and position of the surgical procedure, blood loss, and IV fluid administration. The surgeon may want to perform a neurologic examination as soon as possible after surgery; the timing and doses of anesthetic and analgesic medication should be tailored to accommodate this request, even if the patient is to remain intubated postoperatively. If the patient requires postoperative mechanical ventilation and the surgeon requests an immediate postoperative neurologic examination, we wean anesthetics such as sufentanil or propofol starting up to one hour prior to the end of the procedure, and use low-dose volatile anesthetic thereafter as needed. Use of an electroencephalogram (EEG) obtained from evoked potential monitoring or from a processed EEG monitor may be helpful in guiding the depth of anesthetic. Once the patient moves all extremities, we reanesthetize prior to transport to the ICU. (See "Anesthesia for elective spine surgery in adults", section on 'Postoperative care' and "Management of the difficult airway for general anesthesia in adults", section on 'Extubation'.)

Postoperative pain control — The plan for postoperative pain control must be individualized and will be affected by the degree of spinal injury (eg, level of sensory impairment), associated injuries, perioperative cognitive function, preoperative chronic use of opioids, and the need for postoperative ventilation and sedation. In many cases, a multimodal approach to pain management will be appropriate. (See "Approach to the management of acute pain in adults", section on 'Creating a plan for analgesia'.)

Chronic pain may develop in 26 to 96 percent of SCI patients [78,79] and may be refractory to medical care.

SUMMARY AND RECOMMENDATIONS

●Systemic effects of acute spinal cord injury – Cervical and high thoracic spinal cord injuries (SCIs) are associated with spinal and neurogenic shock, hypotension, bradycardia, and other arrhythmias. Systemic complications of acute SCI (ASCI) can be widespread and can also include pulmonary, gastrointestinal, urologic, and electrolyte disorders. In addition, deep vein thrombosis and loss of thermoregulation are common. (See 'Systemic effects of acute spinal cord injury' above.)

●Prevention of further injury – When general anesthesia is required for patients with SCI, a goal for airway and hemodynamic management should be the prevention of secondary injury to the spinal cord. (See 'Airway management' above and 'Hemodynamic management' above.)

●Airway management

•For patients with cervical and high thoracic SCI, movement of the cervical spine should be minimized during airway maneuvers and throughout the perioperative period. No technique for airway management has been shown to be superior to others for prevention of neurologic deterioration in the patient with an unstable cervical spine. All airway maneuvers are associated with some degree of cervical spine movement. The degree of movement during careful airway management is small, but the implications of even small movements for patients with SCI are unclear. (See 'Cervical spine motion and success during airway management' above.)

•Our general strategy for airway management of patients with cervical SCI, without considerations required for other injuries, is as follows:

-We suggest the use of manual in-line stabilization (MILS), without traction, during all aspects of airway management (figure 1) (Grade 2C). MILS reduces spine motion during airway manipulation. When a hard collar is in place for preoperative spine immobilization, MILS should be established, and then the front of the collar may be removed if more space is needed for adequate mouth opening. Once the airway is secured, the collar can be replaced. (See 'Manual in-line stabilization (MILS)' above.)

-For emergency procedures without anticipated difficulty with airway management, we perform rapid sequence induction and intubation (RSII) with indirect or direct laryngoscopy for patients with low thoracic or lumbar SCI. For patients with cervical or high thoracic SCI, we perform RSII with a video laryngoscope to minimize spine motion and we avoid cricoid pressure. (See 'Cervical spine motion and success during airway management' above.)

-If mask ventilation is required for patients with cervical or high thoracic SCI, when necessary, we insert an oral or nasal airway using outward jaw thrust without neck extension to improve ventilation while minimizing cervical spine movement. (See 'Cervical spine motion and success during airway management' above.)

-We avoid succinylcholine after 48 hours after injury to avoid severe hyperkalemia. (See 'Induction of anesthesia' above.)

-For nonemergency procedures, we perform RSII as indicated by the patient's clinical condition. When RSII is not required, we perform flexible scope intubation (FSI) or indirect laryngoscopy with a video laryngoscope.

-Our decision to intubate awake or asleep depends on the level of patient cooperation and the expected degree of difficulty with all aspects of airway management. (See 'Awake versus asleep intubation' above.)

●Hemodynamic management

•Blood pressure (BP) should be carefully managed in patients with ASCI to preserve spinal cord perfusion and prevent secondary SCI. We suggest maintenance of a mean arterial pressure (MAP) of 85 to 90 mmHg during anesthesia for five to seven days after acute cervical SCI (Grade 2C).

We reduce the dose of anesthetic induction agents for these patients and often start a low-dose phenylephrine infusion (eg, 20 to 40 mcg/minute) during induction for patients without bradycardia. For bradycardic patients, we often administer ephedrine 5 to 15 mg or glycopyrrolate 0.2 to 0.4 mg IV with or without phenylephrine to prevent hypotension. (See 'Induction of anesthesia' above.)

•All patients with ASCI require initial volume resuscitation starting with intravenous (IV) crystalloid, with addition of colloid and blood products as necessary. Many will require administration of vasopressors and/or inotropes for BP support. (See 'Hemodynamic management' above.)

●Postoperative care – The plan for postoperative care of patients with ASCI depends on the level of injury, associated injuries, the intraoperative course, and the need for immediate postoperative neurologic assessment. Many patients with severe cervical cord injuries remain intubated and require mechanical ventilation and intensive care. (See 'Emergence from anesthesia' above.)