Anesthesia for elective spine surgery in adults

INTRODUCTION — Surgical procedures on the spine and spinal cord are common and are performed for a wide variety of conditions. They range in complexity from minimally invasive, single-level decompression to highly complex, multi-stage extensive reconstruction. Operative procedures for degenerative spine disease and herniated disks are most common in those under 60 years of age, while those over 60 years of age most commonly undergo spine surgery for spinal stenosis [1].

Anesthesia providers will increasingly care for patients having spine surgery as the population ages and clinical innovation and technology continue to advance. This topic will discuss preoperative evaluation and intraoperative management of adult patients having elective spine surgery. Selection of patients for surgical treatment and options for surgical treatment are discussed separately.

●(See "Lumbar spinal stenosis: Treatment and prognosis", section on 'Surgical approach'.)

●(See "Subacute and chronic low back pain: Surgical treatment", section on 'Indications for spinal surgery'.)

●(See "Scoliosis in the adult", section on 'Surgical intervention'.)

Postoperative visual loss after prone spine surgery is discussed in detail separately. (See "Postoperative visual loss after anesthesia for nonocular surgery", section on 'ION associated with spine surgery'.)

PREOPERATIVE EVALUATION — Preoperative evaluation should focus on assessment of the airway and the respiratory, cardiovascular, musculoskeletal, and neurologic organ systems.

●Airway evaluation – Airway management may be difficult for patients who undergo cervical or upper thoracic spine surgery, and/or with diseases that distort airway anatomy or restrict neck or jaw movement (eg, osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, neuromuscular disorders, or previous head or neck radiation). In addition, these patients may have instability of the cervical spine, which will affect the choice of intubation technique. (See 'Airway management' below.)

Airway evaluation and management are discussed more fully separately. (See "Airway management for induction of general anesthesia", section on 'Airway assessment'.)

●Pulmonary evaluation – Significant spinal deformity may result in restrictive respiratory physiology, with decreases in vital capacity and total lung capacity, and in some cases pulmonary hypertension and cor pulmonale. For patients with known lung disease who undergo thoracotomy for spine surgery, pulmonary function testing with diffusing capacity (ie, diffusing capacity for carbon monoxide [DLCO]) may be useful for predicting the need for advanced one lung ventilation techniques. (See "One lung ventilation: General principles", section on 'Management of hypoxemia'.)  

●Cardiovascular evaluation – Important considerations for preoperative cardiovascular evaluation include the following:

•Cardiovascular compromise may be the result of the pathology for which spine surgery is being performed (eg, pulmonary hypertension in patients with severe kyphoscoliosis).

•Pulmonary hypertension and congestive heart failure are highly associated with perioperative adverse events after spine surgery [2].

•Many patients who undergo spine surgery are unable to exercise and cannot provide functional assessment.

•When evaluating cardiac perioperative risk, most spine surgeries involving fusion and instrumentation should be classified as intermediate-risk surgery [3,4]. One- or two-level decompression without fusion is classified as low-risk. Preoperative cardiac evaluation is discussed more fully separately. (See "Preoperative evaluation for anesthesia for noncardiac surgery", section on 'Surgical risk'.)

•Most spine surgery is performed in the prone position, which is associated with reduction of cardiac index of 12 to 24 percent compared with supine, due to reduction of venous return and left ventricular compliance in the prone position. (See "Patient positioning for surgery and anesthesia in adults", section on 'Physiologic effects of prone positioning'.)

●Musculoskeletal evaluation – Positioning may be challenging in patients with conditions that restrict range of motion. Patients should be placed in positions that would be comfortable awake. Trial positioning before sedation or induction of anesthesia may be helpful, as limitations may affect decisions about positioning. (See 'Positioning' below and "Patient positioning for surgery and anesthesia in adults", section on 'Trial positioning'.)

●Neuromuscular evaluation – Existing motor and sensory neurologic deficits should be recognized and documented prior to surgery, to facilitate diagnosis of new postoperative deficits. Existing motor deficits may impact both the choice of neuromuscular blocking agent and the site for placement of the neuromuscular block monitor. (See 'Neuromuscular blocking agents (NMBAs)' below.)

●Laboratory evaluation – Existing comorbidities and invasiveness of the anticipated procedure should dictate preoperative laboratory evaluation. Laboratory testing is usually unnecessary for single-level decompressive procedures performed in patients with limited comorbid disease. We perform a baseline hemoglobin, platelet count, serum creatinine and blood bank type and screen for surgical procedures that involve more than two vertebral levels, vertebral fusion and/or instrumentation, or require osteotomies.

ENHANCED RECOVERY AFTER SURGERY (ERAS) — Protocols focused on enhanced recovery are typically initiated preoperatively. ERAS protocols for spine surgery have been published, and like other major surgery, benefits of reduced opioid use and length of stay have been reported, without an increase in adverse effects [5-8]. Principles of enhanced recovery protocols are discussed separately. (See "Anesthetic management for enhanced recovery after major noncardiac surgery (ERAS)".)

CHOICE OF ANESTHETIC TECHNIQUE — General anesthesia is most commonly used for spine surgery, but neuraxial anesthesia may be an option for one- or two-level lumbar laminectomy or disc surgery if the surgeon agrees. Considerations when choosing between neuraxial anesthesia and general anesthesia for all patients are discussed separately. (See "Overview of neuraxial anesthesia", section on 'Preoperative evaluation'.)

For patients who undergo spine surgery:

●We consider spinal anesthesia for patients who will tolerate lying prone for the duration of surgery after assessing the patient's level of anxiety and range of motion of the neck, shoulders, and arms.

●We generally avoid spinal anesthesia for patients for whom we would anticipate difficult airway management; should an airway emergency occur, the patient may have to be turned supine and the airway rapidly secured. (See "Airway management for induction of general anesthesia", section on 'Prediction of the difficult airway'.)

A number of randomized trials have compared regional anesthesia with general anesthesia for lumbar discectomy or laminectomy [9]. No clear difference in morbidity or mortality has been identified, though several short-term benefits of regional anesthesia have been demonstrated. A metaanalysis of 11 trials comparing general with neuraxial anesthesia for lumbar surgery found reduced early postoperative pain, reduced postoperative nausea and vomiting, improved patient satisfaction, and modestly reduced length of hospital stay with neuraxial anesthesia [9]. The quality of evidence for most outcomes was very low or low.

General anesthesia

Intravenous access and hemodynamic monitoring

●For spine surgery that may result in significant blood loss (eg, multilevel spinal fusion, instrumentation, and/or tumor surgery), we place two large bore intravenous (IV) catheters (14 or 16 gauge) or a rapid infusion catheter.

●The decision to use intraarterial or other advanced monitoring depends on patient comorbidities and the planned surgery. We place an arterial catheter for blood pressure monitoring and repeated blood sampling for most major spine procedures with expected significant blood loss (eg, multilevel fusion, tumor surgery).

Choice of anesthetic agents — General principles of the selection of medications for induction and maintenance of anesthesia are discussed in multiple other UpToDate topics. (See "Induction of general anesthesia: Overview" and "Maintenance of general anesthesia: Overview".)

If neuromonitoring is planned during spine surgery, the choice of anesthetic drugs should be tailored to the monitoring modalities used. The effects of anesthetics on various modalities are discussed in detail separately and are shown in a table (table 1). (See "Neuromonitoring in surgery and anesthesia", section on 'Anesthetic effects on neuromonitoring'.)

Neuromuscular blocking agents (NMBAs) — Choice of NMBA for intubation and relaxation during surgery must take into account the plan for neuromonitoring, if applicable, and patient factors. Clinical use of NMBAs during anesthesia is discussed in detail separately. (See "Clinical use of neuromuscular blocking agents in anesthesia".)

●Nondepolarizing NMBAs – If neuromonitoring with electromyography or motor evoked potential is planned, administration of nondepolarizing NMBAs (eg, rocuronium, vecuronium, cisatracurium) should be coordinated with the monitoring team and surgeon, since electromyography (EMG) and motor evoked potential (MEP) monitoring is not possible with complete paralysis. Choice of NMBA in this setting is discussed separately. (See "Neuromonitoring in surgery and anesthesia", section on 'Neuromuscular blocking agents'.) If neuromonitoring is not planned, nondepolarizing NMBAs can be used for intubation, to facilitate surgical positioning, and for muscle relaxation during surgery.

●Succinylcholine – When neuromonitoring is planned, succinylcholine may be used for intubation, with no further NMBA administered, to allow for baseline motor testing within a few minutes of intubation. However, succinylcholine is contraindicated for some patients who are likely to present for spine surgery, such as patients with some neuromuscular disorders (eg, muscular dystrophies) and significant denervation lesions. Use of succinylcholine in such patients can cause severe, potentially life-threatening hyperkalemia. (See "Clinical use of neuromuscular blocking agents in anesthesia", section on 'Adverse effects of succinylcholine'.)

For patients with contraindications to succinylcholine, intubation with high dose remifentanil rather than NMBAs is another option that will not affect neuromonitoring. (See "Rapid sequence induction and intubation (RSII) for anesthesia", section on 'Remifentanil intubation'.)

Airway management — The strategy for airway management for general anesthesia for spine surgery depends on the expected degree of difficulty with mask ventilation, supraglottic airway device ventilation, endotracheal intubation, and the stability of the cervical spine. These issues are discussed separately. (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" and "Anesthesia for adults with acute spinal cord injury", section on 'Airway management'.)

Thoracic spine surgery via thoracotomy may require lung isolation with a double lumen tube or bronchial blocker. (See "Lung isolation techniques".)

Hemodynamic management — We maintain mean arterial pressure (MAP) close to the preoperative baseline blood pressure, when possible, to optimize perfusion of the spinal cord, optic nerve and other visual system structures, and other organs. Vasopressor infusion (eg, phenylephrine) is an effective intervention to maintain mean arterial pressure during spine surgery and does not adversely impact postoperative renal function [10].

Reasons to avoid hypotension during spine surgery include the following:

●Patients with severe spinal stenosis are at risk for spinal cord ischemia.

●Spinal instrumentation and distraction can reduce spinal cord perfusion and result in ischemia.

●Postoperative visual loss (POVL) is a rare but potentially devastating complication of prone spinal surgery; maintaining adequate perfusion of the optic nerve and the brain is an unproven but recommended strategy to minimize the risk of some types of POVL (table 2). POVL is discussed in detail separately. (See "Postoperative visual loss after anesthesia for nonocular surgery".)

●Sustained hypotension may be associated with increased 30 day mortality, and there is increasing evidence that even brief periods of hypotension may be associated with increased risks of acute kidney injury, myocardial and neurologic injury. (See "Hemodynamic management during anesthesia in adults", section on 'Adverse effects of hypotension'.)

We do not use deliberate hypotension in an attempt to reduce blood loss for spine surgery. In addition to the risks associated with hypotension, the benefits with respect to blood loss may be insignificant. Epidural venous plexus pressure and intraosseous pressure, both important determinants of blood loss in spine surgery, are independent of arterial blood pressure [11].

Neuraxial anesthesia — Spinal anesthesia is typically used for neuraxial anesthesia for spine surgery. A continuous epidural technique may be used for postoperative analgesia. (See 'Analgesia after major spine surgery' below.)  

Spinal anesthesia for lumbar surgery can be performed with a variety of techniques and medications. It can be done in the sitting or lateral position using isobaric or hyperbaric local anesthetic, with or without the addition of opioid or epinephrine. For spinal anesthesia, we typically inject 3 mL 0.5% bupivacaine without epinephrine intrathecally, with the dose adjusted for patient factors (eg, height, age, body mass index). We lightly sedate most patients, aiming to avoid respiratory depression. If necessary, the surgeon supplements the anesthetic with a subarachnoid injection of 0.5 to 1 mL of 0.5 percent isobaric bupivacaine under direct vision in the surgical field.

Spinal anesthesia technique is discussed in detail separately. (See "Spinal anesthesia: Technique".)

POSITIONING — Patient position for spine surgery depends on the spinal level and the surgical approach. The surgical plan may require repositioning during the procedure. Goals for positioning are to avoid injury to the eyes, peripheral nerves, and bony prominences, reduce the risk of facial edema, and to maintain low venous pressure at the surgical site. If neuromonitoring with motor evoked potentials is to be used, bilateral bite blocks should be placed between molars after intubation, making sure the tongue and lips will not be injured with jaw clench. Bite blocks should be taped in place and rechecked once the patient is turned prone. Positioning for various levels of spine surgery is described here. Further details of these positions are discussed in detail separately. (See "Patient positioning for surgery and anesthesia in adults".)

●Cervical spine surgery

•The patient's arms are usually tucked at the sides for cervical procedures.

•Anterior procedures are usually done with the patient's head on a padded head rest or relatively immobilized with Tongs.

•For posterior cervical procedures or for procedures requiring intraoperative traction, the Mayfield device with skull pins is often used.

•Cervical spine procedures are rarely performed in the sitting position. Patients in the sitting position are at high risk for intraoperative venous embolism, which is discussed separately. (See "Intraoperative venous air embolism during neurosurgery".)

●Thoracic spine surgery

•The anterior approach requires a thoracotomy with the patient in the lateral position. A double-lumen endotracheal tube may be required to allow deflation of one lung for surgical exposure.

•Posterior thoracic spine surgery is done in the prone position with the head on a foam or gel head rest, in the horseshoe head rest of the Mayfield apparatus, or with skull pins. Depending on the level of the surgery, arms will be either tucked at the sides or placed with the shoulders at 90 degrees with the arms on arm rests.

●Lumbar spine surgery – The anterior approach to the lumbar spine requires a laparotomy, which is done in the supine position, while posterior procedures are usually performed in the prone position.

●The prone position – Pregnant patients scheduled for spine interventions should be positioned in a manner that optimizes utero-placental perfusion. Posterior procedures are usually performed with the patient in the prone position. The process of turning prone, safety precautions, and the physiologic effects of the prone position are discussed in detail separately. (See "Patient positioning for surgery and anesthesia in adults", section on 'Prone'.)

Abdominal compression in the prone position can increase pressure in the epidural venous plexus, and thereby increase blood loss during spine surgery [12]. Prone positioning devices (eg, frames, padding systems, specialized operating tables) that allow positioning so that the abdomen is free from compression and maintain or reduce intraabdominal or bladder pressure are associated with reduced blood loss during spine surgery [13].

BLOOD LOSS DURING SPINAL SURGERY — Major spine surgery can result in significant, and occasionally massive, blood loss. The severity of blood loss increases with increased number of spinal levels fused, age over 50, obesity, surgery for tumors, increased intraabdominal pressure in the prone position, and the performance of transpedicular osteotomy [14-17].

Perioperative transfusion — The decision to transfuse must reflect the patient's comorbidities and the clinical situation in the operating room, including the rate of blood loss. For most patients, a restrictive transfusion strategy is appropriate, with a target hemoglobin of 7 to 8 g/dL. Rationale for transfusion, risks of transfusion, and transfusion thresholds are discussed more fully separately. (See "Indications and hemoglobin thresholds for RBC transfusion in adults".)

Reduction of blood loss and transfusion — Intraoperative blood loss can be reduced by careful positioning to avoid venous congestion at the surgical site, by meticulous surgical technique, by the use of antifibrinolytic agents, and by intraoperative hemodilution. Transfusion can be reduced by intraoperative blood salvage. Induced hypotension is no longer recommended for patients having spine surgery [11,18]. (See "Perioperative blood management: Strategies to minimize transfusions".)

For patients undergoing spinal fusion, we suggest administration of tranexamic acid or epsilon aminocaproic acid and the use of intraoperative cell salvage, to minimize blood loss and transfusion, respectively.

Antifibrinolytics — Antifibrinolytics have been successfully used for decades in many surgical populations. In orthopedic surgical patients, the use of the lysine analogs tranexamic acid (TXA) and epsilon-aminocaproic acid (EACA) are effective when administered as a single dose [19] and when used in multiple dose regimens (ie, multiple boluses or bolus plus infusion) [20]. The optimal dosing and administration for spine surgery has not been determined. Recommendations here are based on available literature and pharmacokinetic properties of the antifibrinolytic medications.

Both TXA and EACA have been consistently shown to reduce estimated blood loss, the need for transfusion, and the total amount of blood transfused during spine surgery [21-24]. There is insufficient evidence to recommend an ideal time to stop the infusion (end of skin closure or extension into the postoperative period). The side effect profiles for both agents have not been shown to cause substantial morbidity or increase the risk of thromboembolic events. For spine fusion cases, we administer either tranexamic acid or epsilon-aminocaproic acid, as follows:

●TXA – Bolus 10 mg/kg IV, followed by infusion 2 mg/kg/hour IV, discontinued at the end of the procedure, dose of maintenance infusion reduced for patients with renal insufficiency

●EACA – Bolus 100 mg/kg IV, followed by infusion 10 to 15 mg/kg/hour, discontinued at the end of the procedure

The decision to use antifibrinolytics in patients deemed at higher risk for thrombotic events should be individualized, taking into consideration patient’s risks for bleeding, transfusion, and thrombotic events. The risk of thromboembolic events is overall low, but the safety of antifibrinolytics in patients at high baseline risk of thromboembolism is uncertain. Patients with coronary stents do not appear to be at increased risk of major adverse cardiac events due to intraoperative use of antifibrinolytics. However, we do not administer antifibrinolytics for patients who will undergo vascular anastomosis or free fibular grafting, or who have a hypercoagulable condition [25]. (See "Perioperative blood management: Strategies to minimize transfusions", section on 'Antifibrinolytic agents'.)

Intraoperative hemodilution — We do not routinely use intraoperative hemodilution for spine surgery, though others do. Hemodilution is labor intensive, there is risk of error, and the effect on transfusion is likely small.

Acute normovolemic hemodilution involves removal of blood (typically 500 to 1500 mL) from the patient shortly after induction of anesthesia, and replacement with crystalloid and/or colloid to maintain normovolemia. The withdrawn blood is reinfused during or shortly after the surgical procedure.

The rationale for intraoperative hemodilution is that fewer red blood cells are lost during surgery because the hemoglobin of the shed blood is lower.

Intraoperative hemodilution is discussed more fully separately. (See "Surgical blood conservation: Acute normovolemic hemodilution".)

Intraoperative blood salvage — A 2010 Cochrane database report found that for orthopedic surgery, intraoperative cell salvage reduces both exposure to allogeneic blood and the number of units of blood transfused [26]. Intraoperative blood salvage complements other methods of blood conservation. Given the high cost of current technology, it becomes cost effective compared with allogeneic blood transfusion when ≥2 units of blood can be salvaged and reinfused. Some Jehovah's Witnesses who will not accept blood transfusion will accept autologous blood transfusion with a closed collection and administration system. Intraoperative blood salvage is discussed in greater depth separately. (See "Surgical blood conservation: Intraoperative blood salvage".)

ANALGESIA AFTER MAJOR SPINE SURGERY — A multimodal opioid sparing pain control strategy should be used for all patients who have surgery, based on patient factors and the expected degree of pain. Pain after one- or two-level decompressive procedures may be controlled with nonopioid analgesics and as-needed low dose opioid, whereas multilevel spine surgery may require an intensive multifaceted postoperative pain control regimen. In addition, many patients who undergo spine surgery are opioid tolerant, making postoperative pain control more challenging. (See "Management of acute pain in the patient chronically using opioids for non-cancer pain" and "Management of acute pain in adults with opioid use disorder".)

Perioperative pain control strategies usually include acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) in patients without contraindications, other nonopioid analgesics in selected patients (ketamine, gabapentinoids, lidocaine infusion, dexamethasone), regional anesthesia techniques when possible, and opioids if necessary.

The overall approach to perioperative pain management, creation of an individualized analgesic strategy, the use of nonopioid analgesics and opioids are discussed in detail separately.

●(See "Approach to the management of acute pain in adults".)

●(See "Nonopioid pharmacotherapy for acute pain in adults".)

●(See "Use of opioids for postoperative pain control".)

Issues specific to spine surgery are discussed here.

●NSAIDs – NSAIDs are effective components of multimodal analgesic regimens. However, there is a concern that NSAIDs may affect bone healing. We use oral or intravenous NSAIDs as part of multimodal pain control in the first 48 hours after spine surgery for patients without contraindications to its use, who have no additional risk factors for nonunion (eg, smoking, long-term NSAID use), and in consultation with the surgeon (table 3). (See "Nonopioid pharmacotherapy for acute pain in adults".)

The literature on the effects of NSAIDs on bone healing is inconclusive. A 2010 systematic review and meta-analysis of 11 case-control and cohort studies, which compared 2067 NSAID-exposed patients with 9984 non-exposed controls, found that the degree of risk (pooled odds ratio [OR]) for nonunion was significantly elevated in NSAID-exposed patients when both moderate quality studies of long-bone fractures and higher-quality studies of spinal fusion were analyzed together (OR 3.0, 95% CI 1.6-5.6) [27]. However, when only the higher-quality studies were considered, a significant increase in risk was not observed (OR 2.2, 95% CI 0.8-6.3). There were no randomized trials that qualified for inclusion in the meta-analysis.

One study included in this systematic review retrospectively analyzed the use of ketorolac as an adjunctive analgesic after spinal fusion surgery, limited to 1.5 mg/kg/day for 48 hours [28]. There was no significant effect on ultimate fusion rates or pseudoarthrosis following posterior spinal fusion and instrumentation.

●Intrathecal opioid – We do not routinely administer intrathecal opioids for analgesia after spine surgery, though others do. Some surgeons prefer to administer intrathecal long-acting opioid (eg, morphine 0.1 to 0.2 mg or hydromorphone 50 to 200 mcg), under direct vision during surgery.  

In one study, intrathecal morphine, administered preoperatively or intraoperatively at a dose of <20 mcg/kg in children and 0.4 mg in adults, was safe and resulted in reduced pain scores and opioid use both adults and adolescents for up to 24 hours after spine surgery [29,30].

●Epidural analgesia – Epidural analgesia is an option for postoperative analgesia after spine surgery, with the catheter placed after the surgical procedure. At our institution, for selected patients the surgeon places an epidural under direct vision just prior to wound closure and tunnels the catheter such that the insertion site is as lateral to the incision as possible. Epidural local anesthetic can cause motor block, which may complicate postoperative neurologic assessment. For patients who have an epidural catheter placed, we administer opioid as the initial dose (hydromorphone 0.5 to 1 mg), and await the postoperative neurologic examination for further epidural dosing. If necessary, low-dose local anesthetic is added postoperatively, adjusted as needed. (See "Continuous epidural analgesia for postoperative pain: Technique and management".)

●Peripheral nerve blocks – The role of peripheral nerve blocks for postoperative analgesia after posterior major spine surgery is unclear. Use of erector spinae plane (ESP) blocks for analgesia after spine surgery has been reported, with conflicting results with respect to pain scores and opioid consumption, and overall a lack of high quality data [31-34]; the author does not use ESP blocks in this setting. ESP block is discussed separately. (See "Erector spinae plane block procedure guide".)

Transversus abdominis (TAP) and quadratus lumborum (QL) blocks may be beneficial for patients who have anterior spinal surgery. For patients who have anterior lumbar spine surgery and when requested by the surgeon, we perform bilateral TAP blocks (20 mL bupivacaine 0.25% with epinephrine for each side). TAP and QL blocks are discussed separately. (See "Transversus abdominis plane (TAP) blocks procedure guide" and "Quadratus lumborum block procedure guide".)

POSTOPERATIVE CARE — Both patient and procedural factors correlate with perioperative morbidity and mortality and should be taken into consideration when developing a plan for postoperative care.

Extubation — The decision to extubate at the end of surgery must take into account the duration of surgery, blood loss and fluid replacement, the surgical procedure performed as it relates to the potential for airway compromise, and patient factors that increase the risk of obstruction (eg, obesity, sleep apnea) or make reintubation more difficult. Patients who have long procedures in the prone position and who receive large volumes of intravenous fluid may develop airway and facial edema, increasing the risk of airway obstruction after extubation. Extubation risk stratification and management of high risk extubation are discussed in detail separately. (See "Extubation following anesthesia", section on 'Extubation risk stratification'.)

Some procedures confer especially high risk of postoperative airway edema, such as anterior-posterior cervical spine surgery. These procedures usually last more than eight hours, with the majority of the procedure performed with the patient in the prone position. In addition, these procedures can result in >1000 mL blood loss and involve surgery and tissue dissection on structures around the airway. All of these factors make airway edema more likely.

Though specific patient and surgical factors affect the decision to extubate, in general our approach to extubation after spine surgery is as follows:

●Patients who have had general anesthesia for one- or two-level decompression in the prone position are routinely extubated at the end of the procedure.

●Patients who have had surgery lasting more than four hours in the prone position are assessed after turning supine at the end of the procedure. If there is significant facial edema, extubation may be delayed, even for a short period in the operating room. The patient is positioned with the head elevated to 30 degrees to allow edema to recede. When the patient is extubated, if there has been significant edema we extubate over a tube changer.

●Patients who have had surgery in the prone position with significant blood loss (>2000 mL); large volume resuscitation with crystalloid, colloid, and blood products; or who have had anterior-posterior spine surgery remain intubated and receive postoperative care in the intensive care unit (ICU).

Retrospective studies have shown correlation between operative duration, intravascular volume replacement, obesity, and number of levels of spinal surgery and the decision to delay extubation at the end of surgery [35-37]. Most patients who required delayed extubation after spine fusion procedures will be extubated in the first 24 hours postoperatively. However, even a limited period of postoperative mechanical ventilation after spine surgery is associated with a higher incidence of postoperative pneumonia [35].

Postoperative disposition — Patients with limited comorbid disease undergoing uncomplicated decompressive procedures may be candidates for short-stay or even outpatient surgery. Patients having more complex spinal surgery require inpatient, and in some cases ICU, postoperative care. Morbidity and mortality after spinal fusion can approach 23 and 0.5 percent, respectively, and up to 10 percent of lumbar spine fusion patients will require care in an ICU [38]. Factors independently associated with increased morbidity after spine surgery include advanced age, male sex, and increased comorbidity burden. Specific comorbid conditions highly associated with perioperative adverse events include pulmonary hypertension, congestive heart failure, renal failure, and presurgical coagulopathy [39].

Long procedures (longer than five hours), combined anterior/posterior spinal procedures, and some procedures involving only the anterior spine, particularly anterior thoracic procedures, are associated with increased perioperative complications and mortality when compared with posterior spine procedures [2,40]. Risk factors for extended hospital length of stay and dismissal to a health care facility other than home after adult spinal deformity surgery include advanced age, osteoporosis, the need for blood transfusion and three level osteotomies [41].    

SPECIAL CONSIDERATIONS

Neuromonitoring — Multimodal intraoperative neuromonitoring (eg, motor evoked potential [MEP], somatosensory evoked potential [SSEP], and electromyography [EMG]), is often used to monitor spinal cord function during surgery on the spinal cord or the vertebral column. Anesthetics and neuromuscular blocking agents must be chosen to minimize effects on neuromonitoring. Intraoperative changes in the expected electrophysiologic responses may be due to anesthetics, physiologic changes, technical monitoring issues, or surgical events (table 4).

Appropriate anesthetic strategy during neuromonitoring and management if changes in electrophysiologic responses occur during surgery are discussed in detail separately (table 1). (See "Neuromonitoring in surgery and anesthesia".)

Staging complex spine procedures — Procedures requiring a combined approach (anterior-posterior) to the spine are commonly longer in duration and are associated with significant blood loss and increased postoperative complications when compared with procedures requiring an isolated anterior or posterior approach. Depending on the planned procedure, the anterior portion can include ureteral stenting, laparotomy, colonic and vascular mobilization, bony exposure, and osteotomies. The posterior portion, again depending on the surgery, can include tumor resection and spinal stabilization procedures.

The anterior and posterior portions of these procedures can be done sequentially during one anesthetic or can be staged with the two approaches performed days apart. Literature comparing outcomes during and after staged or sequential spine procedures is conflicting [42-46]. Planning for these potentially long and complicated procedures requires collaboration between surgery and anesthesia, including plans for postoperative care, giving consideration to staging spine procedures in an effort to reduce prolonged procedures with significant blood loss. A collaborative approach has been endorsed by the American Society of Anesthesiologists and the North American Neuro-Ophthalmology Society and supported by the North American Spine Society [47,48].

SUMMARY AND RECOMMENDATIONS

●Choice of anesthetic technique – General anesthesia is most commonly used for spine surgery. Neuraxial anesthesia is possible for one- or two-level lumbar decompression or discectomy. For patients who will tolerate lying prone, for whom we do not anticipate difficulty with airway management, and with a willing surgeon and patient, we sometimes administer spinal anesthesia. (See 'Choice of anesthetic technique' above.)

●Airway management – Airway management may be difficult for patients having spine surgery, who may present with instability of the cervical spine, decreased range of motion of the neck, or conditions that distort airway anatomy. (See 'Airway management' above.)

●Choice of anesthetic agents – If intraoperative neuromonitoring is used, anesthetic agents must be chosen to minimize interference (table 1). (See 'Neuromonitoring' above and "Neuromonitoring in surgery and anesthesia".)

●Positioning – Positioning for prone surgery should be meticulous, avoiding abdominal compression, pressure on eyes, and soft tissue pressure injury. The head should be positioned level with or above the level of the heart whenever possible to reduce venous congestion and edema of the face, airway, and periorbital tissues. (See 'Positioning' above and "Patient positioning for surgery and anesthesia in adults", section on 'Prone'.)

●Blood loss – Blood loss may be significant or even massive for some spine procedures. We place two large bore intravenous catheters or a rapid infusion catheter and use invasive monitoring (eg, arterial line) for long procedures and for those in which we anticipate significant blood loss. For all patients having prone spine surgery, patients should be positioned to minimize intraabdominal pressure as a measure to reduce blood loss. For patients undergoing spinal fusion, we suggest administration of tranexamic acid or epsilon aminocaproic acid and the use of intraoperative cell salvage (Grade 2B). (See 'Intravenous access and hemodynamic monitoring' above and 'Antifibrinolytics' above and 'Intraoperative blood salvage' above.)

●Hemodynamic management – We maintain mean arterial pressure (MAP) close to the preoperative baseline blood pressure, when possible, to optimize perfusion of the spinal cord, optic nerve and other visual system structures, and other organs. We do not use induced hypotension in an effort to reduce blood loss. (See 'Hemodynamic management' above.)

●Postoperative analgesia – Multimodal opioid sparing analgesia should be used for all patients. (See "Approach to the management of acute pain in adults" and 'Analgesia after major spine surgery' above.)

•Pain after one- or two-level decompressive procedures may be controlled with nonopioid analgesics and low dose as-needed opioids.

•Patients often have severe pain after major spine surgery, and they usually require an intensive multimodal analgesic strategy including opioids. Many patients take opioids chronically, further complicating postoperative analgesia.

•Whether nonsteroidal anti-inflammatory drugs impair bone healing has not been determined. We administer nonsteroidal anti-inflammatory drugs (NSAIDs) postoperatively after consultation with the surgeon.

•Intrathecal opioids and postoperative epidural analgesia are options. For patients who have abdominal incisions for anterior procedures, transversus abdominis plane block or quadratus lumborum blocks are options as well.

●Extubation and postoperative care – The plan for postoperative care for patients having major spine surgery may include delayed extubation and intensive care, especially after long procedures with significant blood loss and large-volume fluid resuscitation. We delay extubation in patients at risk for edema and airway obstruction. (See 'Postoperative care' above.)