Cardiac Assessment Cardiovascular abnormalities are most commonly caused by pulmonary hyper- tension (secondary to chronic hypoxia and hypercapnia). Right ventricular hypertrophy and cor pulmonale may develop as a result of the elevated pulmo- nary resistance. ECG changes associated with pulmonary hypertension and right atrial enlargement (P wave greater than 2.5 mm, R greater than S in V 1 and V 2 ) maybeseenbutareusuallynotevidentuntillateinthediseaseprocess. Mitral valve prolapse can be associated with idiopathic scoliosis Scoliosis is also associated with congenital heart abnormalities [30]. Mitral valve prolapse is common in patients with idiopathic scoliosis with a prevalence of about 25%. If a murmur is heard on physical examination, an echocardiogram is recommended. Echocardiogram is recommended to assess pulmonary hypertension and congenital heart abnormalities Marfan syn drome may be associated with mitral valve prolapse, dilatation of the aortic root and aortic insufficiency. Prophylaxis against infective endocardi- tis should be administered to patients who have mitral valve prolapse or other lesions resulting in disturbances of flow. Neuromuscular Disease Duchenne muscular dystrophy warrants thorough cardiac assessment The most common neuromuscular disease is Duchenne muscular dystrophy, with an incidence of one in 3300 male births. It is inherited as a sex-linked reces- sive condition affecting skeletal, cardiac and smooth muscle. Over 90% of these patients develop a progressive scoliosis when they become wheelchair bound. Patients lack the membrane cytoskeletal protein dystrophin and typically pre- sent between the ages of 2 and 6 years with progressive weakness of proximal muscle groups. Up to one-third of patients have intellectual impairment. Duchenne muscular dystrophy patients have a high incidence of deteriorating lung function and cardiac abnormalities (50±70%). In the later stages of the dis- ease, a dilated cardiomyopathy may occur associated with mitral valve incompe- tence. Dysrhythmias occur and up to 50% of patients have cardiac conduction defects [31]. Cardiac arrest in patients with Duchenne muscular dystrophy has been reported during spinal surgery [32]. Cerebral Palsy Cerebral palsy is a non-progressive disorder of motion and posture and is the result of an injury to the developing brain. Clinical manifestations relate to the area affected and these children require special consideration because of their various disabilities. Visual and hearing deficits are common and will make com- munication difficult. This often leads to anxiety, but premedication has to be bal- anced with the unpredictable response. These patients should be accompanied by their carers at induction and in the recovery room, as they usually know how to communicate with the patient. Their understanding may be greater than seems apparent on first meeting. About one-third of these patients suffer from Anticonvulsive therapy should be continued perioperatively epilepsy and the anticonvulsive therapy should be continued. Respiratory prob- lems can include pulmonary aspiration from reflux, recurrent respiratory infec- tionsandreducedabilitytocough.Theairwayshouldbeassessedfordifficultlar- yngoscopy because of loose teeth and temporomandibular joint dysfunction. Other problems during the perioperative period that require caution may include hypothermia, nausea and vomiting and pain induced muscle spasm [33]. Preoperative Assessment Chapter 14 383 Malignancy Patients with primary or secondary malignant disease of the vertebral column and spinal cord are increasingly being considered for surgery. Metastatic tumors occurthreetofourtimesmorefrequentlythanprimaryneoplasmswithinthe vertebral column, and solitary vertebral lesions are often metastatic in the elderly. The vast majority of neoplastic cord compressions derive from meta- static tumors of the breast, lung, prostate or hematopoietic system. The thoracic spine is the most commonly affected [35]. Cancer patients are prone to complications Thesepatientshavecommonlylostalargeamountofweightandhavereduced physiological reserve. Respiratory complications of malignancy are common in such patients. Further risks include [36]: wound healing disturbance (protein loss) infection pleural effusion pulmonary toxicity (secondary to chemotherapy) increased risk for myocardial infarction (secondary to chemotherapy) metabolic derangements (e.g., hypercalcemia, SIADH) risk of coagulopathies (prostate cancer, hypernephroma) The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is associated with small cell lung tumors, carcinoma of the prostate, pancreas and bladder, and central nervous system neoplasms [37]. Surgery for malignant tumors often requires extensive blood transfusions Prior to surgery enough units of packed red blood cells should be available since spinal decompressive surgery for malignant processes often leads to a large blood loss. Spinal Cord Injury Spinal shock begins immediately after the insult and lasts up to 3 weeks Patients with traumatic spinal injury frequently present for surgical spinal stabi- lization during the period of spinal shock, which is the result of a traumatic sym- pathectomy. It begins almost immediately after the insult and may last for up to 3 weeks [38]. The clinical effects depend on the level of the lesion to the spinal cord and may involve several organ systems. A traumatic sympathectomy occurs below the level of the spinal cord lesion with the risk of hypotension secondary to arteriolar and venular vasodilatation. Injuries at or above T6 are particularly associated with hypotension, as the sympathetic out- flow to splanchnic vascular beds is lost. Bradycardia will occur if the lesion is higher than the sympathetic cardioaccelerator fibers (T1–T4), with the parasympathetic cranial outflow being preserved. A complete cervical cord injury produces a total sympathectomy and therefore hypotension will be more marked. Above the level of the lesion, sympathetic outflow is preserved. Vasoconstriction in the upper body vascular beds and tachycardia may be observed in response to the hypotension resulting from reduced systemic vascular resistance in the lower part of the body. Hypotension associated with spinal cord injury responds poorly to i.v. fluid load- ing, which may cause pulmonary edema. Vasopressors are the treatment of choice. Hypoxia or manipulation of the larynx or trachea during intubation may cause pro- found bradycardia or asystolia in these patients because of the unopposed vagal tone. In these situations atropine may be administered to attenuate the vagal effects. Other causes of hypotension should be excluded such as blood loss associated with other injuries, since a hemorrhagic shock will not be accompanied by a compensa- tory tachycardia. Positive pressure ventilation causes marked arterial hypotension as the systemic vascular resistance cannot be raised to offset the changes in intra- thoracic pressure caused by positive pressure ventilation [38, 39]. 384 Section Peri- and Postoperative Management Ventilatory impairment increases with higher levels of spinal injury. A high cer- vical lesion that includes the diaphragmatic segments (C3–C5) will result in Perioperative management of spinal cord injured patients is demanding respiratory failure and death unless artificial pulmonary ventilation is insti- tuted. Mid to low cervical spine injuries (C5–C8) spare the diaphragm but the intercostal and abdominal muscles may be paralyzed. Further complications [39] of the paralysis due to a cervical spinal cord injury include: an inadequate cough mechanism ineffective secretion clearing paradoxical rib movement on spontaneous ventilation decreased vital capacity (20–50%) decrease in functional residual capacity (10–20%) loss of active expiration paralytic ileus gastric distension thromboembolism The paralytic ileus and the gastric distension increase abdominal pressure, fur- ther compromising diaphragmatic excursion. This gastric distension can be reduced by placement of a nasogastric tube and attaching it to suction. Autonomic dysreflexia is a syndrome associated with chronic spinal cord injury and may be present after 3–6 weeks following the spinal cord injury. This condition is characterized by extreme autonomic responses such as: severe paroxysmal hypertension associated with bradycardia ventricular ectopy various degrees of heart block Autonomic dysreflexia may be present after 3 – 6 weeks following the spinal cord injury The initiation of these events can be stimulation of nerves below the level of the spinal cord lesion (for example, cutaneous, rectal, urological, peritoneal stimula- tion). Injuries higher than T7 have an 85% chance of producing serious cardio- vascular derangement [40]. Treatment involves removal of the noxious stimulus (e.g., bladder distension), increasing the level of analgesia and/or anesthesia and the administration of direct-acting vasodilators. If left untreated, the syndrome can provoke a hypertensive crisis causing seizures, myocardial ischemia or cere- bral hemorrhage. Avoidance of this phenomenon in scheduled patients with chronic spinal injury necessitates either regional or general anesthesia despite a lack of motor or sensory function in the area of the surgery. Recapitulation Patient assessment. The preanesthetic evaluation of patients for spinal surgery follows the general ap- proach used before any patient is given anesthesia. Particular care should be given to the respiratory, cardiovascular, and neurological systems that can all be affected by the spinal pathology. The aim of the preoperative visit is to explain the anesthetic proce- dure and reduce the patient’s anxiety. The need for preoperative testings is determined by the patient’s age and health and by the scope of the procedure. Organ-specific assessment. When assessing the airway, difficulties should always be considered. Traumatized patients or those with head injury are assumedtohaveanunstablecervicalspineuntil this has been ruled out; the stability of the spine should be discussed preoperatively with the sur- geon. These patients may be managed with awake fiberoptic intubation after topical anesthesia. Re- spiratory function should be assessed by a thor- ough history, focusing on functional impairment, and reversible causes of pulmonary dysfunction should be optimized. Because of the increased prevalence of coronary heart disease, cardiac as- sessment is a challenge to the anesthesiologist. Specialattentionshouldbepaidtopatientsbear- Preoperative Assessment Chapter 14 385 ing an increased risk where coronary heart disease has not been proven. Most pediatric cardiac com- promise is a result of the underlying pathology, e.g., in patients with Duchenne muscle dystrophy, Mar- fan syndrome or scoliosis. Preoperative neurologi- cal examination should be documented since the anesthesiologist is responsible for avoiding further neurological deterioration during tracheal intuba- tion and patient positioning. In scoliosis the tho- racic deformity causes restrictive lung disease that can progress to irreversible pulmonary hyperten- sion and cor pulmonale. Duchenne muscle dystro- phy is a neuromuscular disease with a high inci- dence of lung function and cardiac abnormalities. Patients with malignancy have impaired physiolog- ical reserves, and metabolic derangements and sur- gery for malignant processes often lead to large blood loss. Spinal injury patients frequently present during spinal shock, a traumatic sympathectomy below the lesion which begins almost immediately after the insult and which may last up to 3 weeks. Vasopressors are the treatment of choice for the resulting hypotension. Autonomic dysreflexia may be present after 3 –6 weeks following the spinal cord injury and is characterized by extreme auto- nomic responses such as severe paroxysmal hyper- tension. Avoidance of this phenomenon necessi- tates regional or general anesthesia for patients with chronic spinal cord damage scheduled for sur- gery. Perioperative drug therapy. It is important to decide which drugs to stop, continue or add. Peri- operative prophylaxis with beta-blocking agents in patients with increased cardiac risk can improve postoperative survival rate. Key Articles Mangano DT (1999) Assessment of the patient with cardiac disease: an anesthesiolo- gist’s paradigm. Anesthesiology 91:1521 –6 Systematically presented suggestions for selection of preoperative tests and therapy, based on the presence of coronary artery disease (or risk factors) and the patient’s func- tional capacity. Lee TH, Marcantonio ER, Mangione CM, Thomas EJ, Polanczyk CA, Cook EF, Sugar- baker DJ, Donaldson MC, Poss R, Ho KK, Ludwig LE, Pedan A, Goldman L (1999)Deriva- tion and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation 100:1043 – 9 Useful and clinically applicable index for cardiac risk stratification in the context of elec- tive major non-cardiac surgery. The authors outlined six risk factors for cardiac compli- cations such as high risk type of surgery, ischemic heart disease, congestive heart failure, history of cerebrovascular insult, insulin dependent diabetes mellitus and increased pre- operative serum creatinine. Hambly PR, Martin B (1998) Anaesthesia for chronic spinal cord lesions. Anaesthesia 53:273 – 89 An excellent review of this topic. Mangano DT, Layug EL, Wallace A, Tateo I (1996) Effect of atenolol on mortality and car- diovascular morbidity after noncardiac surgery. Multicenter Study of Perioperative Ischemia Research Group. N Engl J Med 335:1713 – 20 In patients who have or are at risk for coronary artery disease and who are undergoing non-cardiac surgery, it has been shown by these authors that the administration of ateno- lol throughout hospitalization can substantially reduce mortality and cardiovascular events after discharge from the hospital, particularly during the first 6–8 months after surgery, and the effects on survival persist for at least 2 years. 386 Section Peri- and Postoperative Management References 1. Ali FE, Al-Bustan MA, Al-Busairi WA, Al-Mulla FA, Esbaita EY (2006) Cervical spine abnor- malities associated with Down syndrome. Int Orthop 30:284–289 2. American Society of Anesthesiologists Task Force on Management of the Difficult Airway (2003) Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 98:1269–77 3. Amzallag M (1993) Autonomic hyperreflexia. Int Anesthesiol Clin 31:87–102 4. Boushy SF, Billig DM, North LB, Helgason AH (1971) Clinical course related to preoperative pulmonary function in patients with bronchogenic carcinoma. Chest 59:383–91 5. Bramlage P, Pittrow D, Kirch W (2005) Current concepts for the prevention of venous thromboembolism. Eur J Clin Invest 35 (Suppl 1):4–11 6. Byrne TN (1992) Spinal cord compression from epidural metastases. N Engl J Med 327:614–9 7. Cabana F, Pointillart V, Vital JM, S´en´egas J (2000) Postoperative compressive spinal epidural hematomas: 15 cases and a review of the literature. Rev Chir Orthop 86:335–345 8. Chen SH, Huang TJ, Lee YY, Hsu RW (2002) Pulmonary function after thoracoplasty in ado- lescent idiopathic scoliosis. Clin Orthop 399:152– 61 9. CrosbyET,CooperRM,DouglasMJ,DoyleDJ,HungOR,LabrecqueP,MuirH,MurphyMF, Preston RP, Rose DK, Roy L (1998) The unanticipated difficult airway with recommenda- tions for management. Can J Anaesth 45:757–76 10. Dearborn JT, Serena SH, Clifford BT, Bradford DS (1999) Thromboembolic complications after major thoracolumbar spine surgery. Spine 24 (14):1471–1476 11. Desbordes JM, Mesz M, Maissin F, Bataille B, Guenot M (1993) Retrospective multicenter studyofpreventionofthromboemboliccomplicationsafterlumbardiscsurgery.Neurochi- rurgie 39 (3):178–181 12. Dzankic S, Pastor D, Gonzalez C, Leung JM (2001) The prevalence and predictive value of abnormal preoperative laboratory tests in elderly surgical patients. Anesth Analg 93:301–8 13. Engelhardt T, Webster NR (1999) Pulmonary aspiration of gastric contents in anaesthesia. Br J Anaesth 83:453–60 14. Faciszewski T, Winter RB, Lonstein JE, Denis F, Johnson L (1995) The surgical and medical perioperative complications of anterior spinal fusion surgery in the thoracic and lumbar spine in adults. A review of 1223 procedures. Spine 20:1592–9 15. Ferguson MK (1999) Preoperative assessment of pulmonary risk. Chest 115:58S–63S 16. Findlow D, Doyle E (1997) Congenital heart disease in adults. Br J Anaesthesia 78:416–430 17. Geerts WH, Pineo GF, Heit JA, Bergqvist D, Lassen MR, Colwell CW, Ray JG (2004) Preven- tion of venous thromboembolism. The seventh ACCP conference on antithrombotic and thrombolytic therapy. Chest 126:338–400S 18. Gerlach R, Raabe A, Beck J, Woszczyk, Seifert V (2004) Postoperative nadroparin adminis- tration for prophylaxis of thromboembolic events is not associated with an increased risk of hemorrhage after spinal surgery. Eur Spine J 13:9–13 19. Hall JC, Tarala RA, Tapper J, Hall JL (1996) Prevention of respiratory complications after abdominal surgery: a randomised clinical trial. BMJ 12:148–52 20. Hambly PR, Martin B (1998) Anaesthesia for chronic spinal cord lesions. Anaesthesia 53:273–89 21. Kawakami N, Mimatsu K, Deguchi M, Kato F, Maki S (1995) Scoliosis and congenital heart disease. Spine 20:1252–5 22. Kearon C, Viviani GR, Kirkley A, Killian KJ(1993) Factors determining pulmonary function in adolescent idiopathic thoracic scoliosis. Am Rev Respir Dis 148:288–94 23. Kinnear WJ, Johnston ID (1993) Does Harrington instrumentation improve pulmonary function in adolescents with idiopathic scoliosis? A meta-analysis. Spine 18:1556–9 24. Kou J, Fischgrund J, Biddinger A, Herkowitz H (2002) Risk factors for spinal epidural hema- toma after spinal surgery. Spine 27 (15):1670–1673 25. Lee TH, Marcantonio ER, Mangione CM, Thomas EJ, Polanczyk CA, Cook EF, Sugarbaker DJ, Donaldson MC, Poss R, Ho KK, Ludwig LE, Pedan A, Goldman L (1999) Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation 100:1043–9 26. Mangano DT, Layug EL, Wallace A, Tateo I (1996) Effect of atenolol on mortality and cardio- vascular morbidity after noncardiac surgery. Multicenter Study of Perioperative Ischemia Research Group. N Engl J Med 335:1713–20 27. Mangano DT (1999) Assessment of the patient with cardiac disease: an anesthesiologist’s paradigm. Anesthesiology 91:1521–6 28. Mansel JK, Norman JR (1990) Respiratory complications and management of spinal cord injuries. Chest 97:1446– 52 29. Matti MV, Sharrock NE (1998) Anesthesia on the rheumatoid patient. Rheum Dis Clin North Am 24:19–34 Preoperative Assessment Chapter 14 387 30. Meyer B, Jende C, Rikli D, Moerloose de P, Wuillemin WA (2003) Periinterventionelles Man- agement der oralen Antikoagulation: Fallbeispiele und Empfehlungen. Schweiz Med Forum 9:213 31. Morris P (1997) Duchenne muscular dystrophy: a challenge for the anaesthetist. Paediatr Anaesth 7:1–4 32. Munro J, Booth A, Nicholl J (1997) Routine preoperative testing: a systematic review of the evidence. Health Technology Assessment 1:I–IV; 1–62 33. Nolan J, Chalkiadis GA, Low J, Olesch CA, Brown TC (2000) Anaesthesia and pain manage- ment in cerebral palsy. Anaesthesia 55:32–41 34. Oda T, Fuji T, Kato Y, Fujita S, Kanemitsu N (2000) Deep venous thrombosis after posterior spinal surgery. Spine 25 (22):2962–2967 35. Pehrsson K, Larsson S, Oden A, Nachemson A (1992) Long-term follow-up of patients with untreated scoliosis. A study of mortality, causes of death, and symptoms. Spine 17:1091 – 6 36. Poldermans D, Boersma E, Bax JJ, Thomson IR, van de Ven LL, Blankensteijn JD, Baars HF, Yo TI, Trocino G, Vigna C, Roelandt JR, van Urk H (1999) The effect of bisoprolol on periop- erative mortality and myocardial infarction in high-risk patients undergoing vascular sur- gery. Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography Study Group. N Engl J Med 341:1789–94 37. Raskob GE, Hirsh J (2003) Controversies in timing of the first dose of anticoagulant prophy- laxis against venous thromboembolism after major orthopaedic surgery. Chest 124:379S– 385S 38. Reid JM, Appleton PJ (1999) A case of ventricular fibrillation in the prone position during back stabilisation surgery in a boy with Duchenne’s muscular dystrophy. Anaesthesia 54:364–7 39. Sethna NF, Rockoff MA, Worthen HM, Rosnow JM (1988) Anesthesia-related complications in children with Duchenne muscular dystrophy. Anesthesiology 68:462–5 40. Sidi A, Lobato EB, Cohen JA (2000) The American Society of Anesthesiologists’ Physical Status:categoryVrevisited.JClinAnesth12:328–34 41. Sorensen JB, Andersen MK, Hansen HH (1995) Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in malignant disease. J Intern Med 238:97–110 42. Stiller K, Montarello J, Wallace M, Daff M, Grant R, Jenkins S, Hall B, Yates H (1994) Efficacy of breathing and coughing exercises in the prevention of pulmonary complications after coronary artery surgery. Chest 105:741–7 43. Supkis DE, Varon J (1998) Uncommon problems related to cancer. In: Benumof J (ed) Anes- thesia and uncommon diseases, 4th edn. Philadelphia: WB Sanders Co., 545–60 44. Vedantam R, Lenke LG, Bridwell KH, Haas J, Linville DA (2000) A prospective evaluation of pulmonary function in patients with adolescent idiopathic scoliosis relative to the surgical approach used for spinal arthrodesis. Spine 25:82–90 45. Wolfs JF, Peul WC, Boers M, Tulder van MW, Brand R, Houwelingen van HC, Thomeer RT (2006) Rationale and design of The Delphi Trial – I(RCT)2: international randomized clini- cal trial of rheumatoid craniocervical treatment, and intervention-prognostic trial compar- ing ’early’ surgery with conservative treatment. BMC Musculoskelet Disord 7:14 46. Yentis SM (2002) Predicting difficult intubation – worthwhile exercise or pointless ritual? Anaesthesia 57:105–9 47. Zaugg M, Tagliente T, Lucchinetti E, Jacobs E, Krol M, Bodian C, Reich DL, Silverstein JH (1999) Beneficial effects from beta-adrenergic blockade in elderly patients undergoing non- cardiac surgery. Anesthesiology 91:1674–86 388 Section Peri- and Postoperative Management 15 Intraoperative Anesthesia Management Juan Francisco Asenjo Core Messages ✔ Communicate with your anesthetist. Talk to him before surgery if you have particular concerns aboutthepatientortheprocedureyouare planning. Let him know constantly about how things are going during the surgery. Share your thoughts and team up ✔ Patients having major spine procedures must be properly assessed by the anesthesia team beforehand to increase safety and success in the perioperative period ✔ Special airway management and positioning could be challenging for the anesthesia team, sometimes involving longer preparation ✔ The anesthesia technique must allow for reli- able neuromonitoring; SSEP recordings and wake-up test, short-acting drugs, TIVA and low- dose gases are indicated ✔ Blood preservation is a must. Careful surgical technique and positioning, antifibrinolytics, blood predeposit, cell recovery and controlled hypotension (CH) are the way to go. CH is con- traindicated in the presence of spinal cord com- pression (tumor, trauma, etc.) ✔ Some cervical spine surgeries, long cases or those with massive transfusions might require postoperative ventilation ✔ Good pain control after surgery is associated with lower rates of postoperative chronic pain conditions and faster recovery. Multimodal analgesia is the cornerstone. NSAIDs could be controversial, but in low doses they are 17 times less likely than smoking to be linked to malunion ✔ Anesthesia should be tailored to fast-track min- imally invasive spine surgery, emphasizing pre- vention of nausea, vomiting and pain control Historical Background Precise information is not available about the first anesthesia for spine surgery. Definitive improvements began in the 1950s with the use of muscle relaxants, oro- tracheal intubation, introduction of halothane and more generous use of intrave- nous crystalloids. In the 1970s the wake-up test was described to assess the integ- rity of the spinal function. At the same time larger doses of opiates became popular to help maintain stable hemodynamic conditions and better pain control intra- and postsurgery. In the 1980s and 1990s new short-acting drugs contributed to the enhancement of the perioperative experience in patients having day surgery pro- cedures, as well as permitting better neurophysiologic monitoring. Goals of Anesthesia in Spinal Surgery Optimal teamwork between the surgeon and anesthetist is a prerequisite for success- ful surgery The role of anesthesia care in spinal surgery must be appreciated within the context of comprehensive perioperative care where a dedicated team takes care of a patient from preoperative planning and perioperative care to rehabilitation and discharge. In many places this is accomplished through the design of “Clinical Pathways,” a Peri- and Postoperative Management Section 389 road map for a particular surgical procedure with standardization of each step to reduce variability, cost and errors. The anesthesia contribution is a key component in this continuum. In a successful Clinical Pathway all players have agreed upon a road map, they have contributed the best evidence from their fields and everybody understands his or her own role and each other’s inputs. In this chapter the most relevant features of anesthesia for spinal surgical procedures are discussed. Partic- ular emphasis on trauma, scoliosis, and degenerative and cancer surgery is given. Preoperative Patient Assessment Anesthesia for spine surgery canonlybeasgoodasthe preoperative assessment and optimization Recommendations for preoperative assessment, diagnostic work-up and condi- tion dependent patient optimization have been provided in Chapter 14 .Safe and efficient anesthesia for spinal interventions depends crucially on the quality of the preoperative assessment and patient optimization. A detailed preoperative assessment minimizes life-threatening risks and helps to avoid intra- and post- operative complications. Optimal communication between surgeon and anesthetist is mandatory for successful surgery The surgeon and anesthesiologist must team up, discuss and plan the opera- tive procedure in advance, particularly in nonroutine cases. Good preoperative communication and a clear bilateral understanding of the procedure and the overall condition of the patient are prerequisites to successful surgery. Although seemingly trivial, the consequences of these rules being ignored are often seen in daily clinical practice. Induction of Anesthesia Patients being admitted for surgery of the spine benefit from premedication with gabapentin. Our experience confirms recent publications [80] supporting the use of 300–600 mg before going to the operating room. It provides mild sedation and a powerful antihyperalgesic effect. If a wake-up test (WUT) is considered, benzodiaz- epines or other amnesic drugs are not recommended since the patient will not retain theinformationabouttheWUTprovidedbeforethe inductionofgeneralanesthesia. Patient identification and type and level of procedure must be checked prior to anesthesia Prior to starting the anesthetic procedures, the identification of the patient, the type of procedure and the level to be operated at (which is key in spine sur- gery) must be checked and confirmed to avoid “wrong patient, wrong side and wrong site surgery” particularly if patients with identical surnames are on the operating list. Before starting the anesthetics, the minimum standard monitoring for gen- eral anesthesia in an otherwise healthy patient undergoing low risk spine surgery encompasses: hemoglobin-O 2 saturation noninvasive blood pressure end-tidal CO 2 continuous ECG The patient’s preoperative condition and type of surgery will dictate the use of other monitoring before starting the operation. At least one large bore i.v. cannula should be in place prior to the induction of anesthesia and for major cases. A second cannula is inserted after the patient is asleep unless a central venous catheter is considered. The choice of induction agent (propofol, thiopental, opiates, etomidate or inhaled agents in children) will depend on the general condition of the patient and the presence of trauma associated hypovolemia, cardiac conditions and cord com- 390 Section Peri- and Postoperative Management pression with marginal blood perfusion. The choice of muscle relaxants to facilitate the intubation will be influenced by conditions like full stomach, gastroesophageal reflux and trauma. Nondepolarizing agents such as rocuronium, vecuronium and cisatracurium have a safe record and are widely used today in spine surgery. Suc- Succinylcholine should be avoided in patients with muscular dystrophy and spinal cord injury cinylcholine should be avoided in patients with muscular dystrophy as well as in patients with spinal cord injury between 3 and 180 days postdenervation because of the potential for hyperkalemia, secondary arrythmias, and cardiac arrest. Acute denervation induces an increment in the number of cholinergic receptors in the perijunctional area. Succinylcholine is a depolarizing type of muscle relaxant; therefore in this condition it will release massive amounts of potassium [30, 70]. Airway Control and Endotracheal Intubation A decision should be made whether to gain control of the airway in advance of or after the induction of anesthesia to assess neurological status after airway manipu- lation and positioning the patient on the table. Patients with unstable C-spine or using a halo vest might need fiberoptic intubation and awake positioning to ensure preservation of neurological function. If awake positioning is needed with traction devices anchored to the skull (e.g., a skull clamp or Mayfield head support), infiltrat- ing the areawherethepinsare going to be placed(with 4–6ml ofbupivacaine0.25% with epinephrine 5 μg/ml at each point) at least 10 min prior to pin insertion is sug- gested. Occasionally a low-dose infusion of remifentanyl (0.05–0.1 μg/kg/min) is maintained during the whole procedure of intubation and positioning. In the event that the patient’s mental status is not reliable enough to ensure a safe surgical posi- tioning, an alternative is to do a baseline somatosensory evoked potential (SSEP)/ motor evoked potential (MEP) recording before anesthesia and positioning and compare it to the one immediately after installation on the surgical table ( Table 1 ). Table 1. Indications for awake fiberoptic intubation Absolute Relative prior occipitocervical fusion history of difficult intubation cervical spinal cord compression prior extensive C-spine fusion patient to be positioned awake on the table risk of aspiration cervical spine trauma halo vest in position atlantoaxial instability severe kyphoscoliosis orofacial malformations There is controversy as to whether direct laryngoscopy is a major factor contrib- uting to cord injuryin patients with cervical spine instability [48]. In this setting, however, other factors such as hypotension and patient positioning may be even more important. Laryngoscopy with manual inline stabilization by the surgeon Direct laryngoscopy should be avoided in patients with spinal cord compromise or with a stiff collar is an accepted means of intubation for many patients with an unstable cervical spine as long as movement of the neck can be avoided [48]. Patients with difficult airways may require fiberoptic intubation, a GlideScope device (a fiberoptic laryngoscope with a screen, see Fig. 1) or a laryngeal airway mask (the “fast track”) to gain airway control. Careful freezing of the airway with local anesthetic is important to avoid coughing during tube placement in patients with unstable C-spine. Inthecaseofanterioraccesstothethoracicspine,selectivecollapseofthe ipsilateral lung facilitates performance of the procedure by the surgeon. Some choices exist in this situation between: a regular orotracheal (OT) tube with a bronchial blocker, which is possibly thefirstoption.ItrequiresaregularOTtubetobeplaced,followedbyfiber- Intraoperative Anesthesia Management Chapter 15 391 Figure 1. GlideScope Direct laryngoscopy without moving the head or C-spine. Observe on the screen the deflated cuff of the endotra- cheal tube under the epi- glottis crossing the vocal cords. optic deployment of a bronchial blocker (type Cohen or Arndt) similar to a Fogarty catheter to restrict the ventilation to the nondependent lung. It is the simplest way of isolating and deflating the lung. aUniventOTtube,whichisaslightlylargertubebecauseofabronchial blocker channel built-in to its wall. This tube is placed in the trachea like a regularOTtube.Thebuilt-inbronchialblockerisadvancedunderdirect fiberscopic vision through its channel to the main bronchus of the nonde- pendent lung. It is the fastest way of isolating the lung. a classic double lumen device which is very reliable, but which can be more traumatic for the airway and vocal cords. If the patient remains intubated in thepostop,thisistheonlytypeoftubethatwillneedtobechangedfora regular one. Placement of this type of tube may also be more difficult in patients with complex airways. Standard use of the more expensive reinforced armored orotracheal tube in patients operated on in the prone position is not clearly justified in the literature [34]. Furthermore, if the patient bites the armored tube (for instance, face-down during a WUT or while on ventilator support in the recovery room or ICU), it will remain deformed and collapsed, diminishing or totally blocking the gas flow, causing a major problem to breathing. Changing the tube with the patient in the prone or lateral position or during cervical spine surgery might be catastrophic. A nasogastric or orogastric tube is routinely passed intraoperati- vely and removed before extubation in anterior C-spine procedures to help the surgeon identify the esophagus and decrease postoperative nausea and vomiting. For anterior lumbar approaches, the stomach is decompressed of gas and secre- Careful eye and face protection is crucial tions by using the gastric tube. Careful eye protection with cream, occlusive tape and peripheral padding is mandatory in particular in patients positioned prone or in anterior approaches to the cervical spine ( Fig. 2). In prepping the neck for posterior approaches, irritant solutions might reach the eyes from behind, remaining there for hours with the potential for severe corneal damage. 392 Section Peri- and Postoperative Management . degrees of heart block Autonomic dysreflexia may be present after 3 – 6 weeks following the spinal cord injury The initiation of these events can be stimulation of nerves below the level of the spinal. chance of producing serious cardio- vascular derangement [40]. Treatment involves removal of the noxious stimulus (e.g., bladder distension), increasing the level of analgesia and/ or anesthesia and the. integ- rity of the spinal function. At the same time larger doses of opiates became popular to help maintain stable hemodynamic conditions and better pain control intra- and postsurgery. In the 1980s and