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J Bone Joint Surg 83A(8):1285–92 Intraoperative Anesthesia Management Chapter 15 415 16 Postoperative Care and Pain Management Stephan Blumenthal, Alain Borgeat Core Messages ✔ The necessity for careful postoperative assessment of the different organ systems is self-evident ✔ Perioperative tachycardias are often combined with ischemic episodes, and their treatment is mandatory because of the high mortality of perioperative myocardiac infarction ✔ Intensive insulin therapy can reduce morbidity and mortality ✔ Following cervical spine surgery, perform air- way assessment before extubation. Suction drainage and close surveillance minimize the risk of unrecognized bleeding ✔ Aggressive postoperative pulmonary care mini- mizes the risk of respiratory complications ✔ Close neurological surveillance is mandatory to detect deterioration ✔ Postoperative paralytic bowel dysfunction can be ameliorated by thoracic epidural analgesia ✔ Spinal surgery is painful and a multimodal approach for peri- and postoperative analgesia is mandatory ✔ Opioid-related side-effects are independent of the route of administration ✔ Administration of regional anesthesia (e.g., epi- dural techniques) following complex spinal sur- gery may be of great help Postoperative Care Major spinal surgery is prone to complications but can be minimized with proper postoperative care Despite advances in anesthesia care and surgical techniques, major surgery is still prone to undesirable consequences [6] such as: infection thromboembolic complications cardiorespiratory morbidity cerebral dysfunction postoperative nausea and vomiting gastrointestinal paralysis pain fatigue prolonged convalescence The key pathogenetic factor in postoperative morbidity is the surgical stress response with subsequent increased demands on organ function [6]. One of the key issues for the anesthesiologist is to decrease this surgical stress response as far as possible to limit its adverse effects. Patients undergoing spinal surgery frequently have significant comorbidities which can have a significant impact on the postoperative recovery. Surgery can further compromise the organ system as a result of: significant blood loss requiring mass transfusions coagulopathy Peri- and Postoperative Management Section 417 prolonged anesthesia with the problem of hypothermia residual impaired pulmonary function difficulties in acute postoperative pain management Perioperative tachycardia often is combined with ischemic episodes Even a single perioperative ischemic episode increases the risk of cardiac mor- tality within the ensuing 2 years. Most of these ischemic events are clinically silent and can only be detected with continuous ECG control. They are usually combined with perioperative tachycardia, which can be either a cause of or a reaction to ischemia. Treatment of a perioperative tachycardia is mandatory since it corrects the imbalance between oxygen supply and oxygen consumption and therefore has a cardioprotective effect. Perioperative myocardiac infarction has a high mortality P erioperative myocardiac infarction most often occurs during the first post- operative day and has a mortality rate which remains high, although it decreases with duration after surgery [25]. Intensive insulin therapy can reduce morbidity and mortality Hyperglycemia and insulin resistance arecommoninpostoperativeandcriti- cally ill patients, even if the patients have not previously had diabetes mellitus. Intensive insulin therapy to maintain blood glucose at or below 6.1 mmol/l can reduce morbidity and mortality, compared to a more conventional treatment with insulin infusion only when blood glucose exceeds 11.9 mmol/l [28]. Since diabetes mellitus is recognized as a risk factor of infection after spinal surgery [9, 14], appropriate insulin therapy may help to reduce the incidence of postopera- tive wound infection as has been shown in the context of other operations [11]. Postoperative Ventilation or Extubation Most spinal surgery patients, including those who have undergone posterior fusion, can be extubated shortly after the procedure if preoperative pulmonary function was acceptable. Extubation is also advantageous since the neurological assessment is facilitated. However, residual narcotics or muscle relaxants can lead to hypoventilation or apnea, especially in patients with an associated neuro- muscular disease. The need for postoperative ventilation [23, 29] is determined by patient and surgery related factors ( Table 1). Frequently, it is necessary only to provide artificial ventilation for a few hours in the postoperative care unit, until hypothermia and metabolic derangements have been corrected. Table 1. Influences on the need for postoperative ventilation Patient-related factors Surgery-related factors presence of a preexisting neuromuscular disorder prolonged procedure (>5 h) severe restrictive pulmonary dysfunction with a preopera- tive < 35 % predicted vital capacity congenital cardiac abnormality right ventricular failure obesity exposing > 3 vertebral bodies thoracic approach blood loss >30 ml/kg transfusion of large volumes of blood and fluid hypothermia Cervical Spine Surgery Perform airway assessment before extubation At the conclusion of anterior cervical spine surgery, before extubation, it is advis- able to perform a thorough airway assessment, in order to avoid a “can’t intubate, can’t ventilate” situation. This can be done by direct laryngoscopy, fiberoptic evaluation or by performing a cuff test. Suction drainage and close surveillance minimize the risk of unrecognized bleed- ing after anterior cervical spine surgery Postoperative bleeding after anterior cervical spine surgery can become a life- threatening situation when reintubation is impossible due to the hematoma pres- sure. In such cases, on-site emergency opening of the wound and reintubation or tracheotomy is the only means to save the patient. We therefore recommend rou- 418 Section Peri- and Postoperative Management tine suction drainage after anterior cervical spine surgery to minimize the risk of this delirious complication and we keep these patients in the recovery room over- night for surveillance. Thoracic Spine Surgery Anterior thoracic and thoracolumbar approaches usually require chest tube placement. These drains should be checked regularly to ensure patency. Obstruc- tion may lead to a pneumo- or hemothorax. This should always be considered as a potential cause of postoperative respiratory distress. Aggressive postoperative pulmonary care minimizes the risk of atelectasis and pneumonia Aggressive pulmonary care, including spirometry, physiotherapy and early mobilization, is necessary to avoid postoperative atelectasis and pneumonia. If prolonged periods of mechanical ventilation are necessary because of respi- ratory insufficiency, the endotracheal tube should be replaced by a cuffed trache- ostomy tube. This should be performed sooner rather than later if prolonged ventilation is anticipated. Hemodynamic Assessment Continued hemorrhage remains a concern during the postoperative period and careful monitoring is essential with regard to: blood pressure urine output central venous pressure wound drainage Gravity suction drainage and correction of hemo- stasis reduce excessive postoperative bleeding If postoperative bleeding is considerable, removal of the vacuum can solve the problem in the vast majority of cases. If coagulation abnormalities are suspected from clinical findings, the hemostasis parameter should be checked. Neurological Assessment Neurological surveillance is mandatory to detect neurological deterioration Surgeons prefer patients to be conscious and able to respond to commands immediately after anesthesia for early neurological assessment [20]. Therefore, postoperatively patients should be adequately analgo-sedated to allow neurolog- ical evaluation, and motor control of the extremities should be possible at any time. Neurological control should be performed regularly at short intervals to detect neurological deterioration. Magnetic resonance imaging should be per- formed to determine thecauseofadenovo neurological deficit When such a finding is noted, an immediate investigation should be done to determine the cause and reversibility of the process. When available, magnetic resonance imaging should be performed to detect extrinsic spinal cord compres- sion by bone, intramedullary swelling or hematoma. After correction of severe spinal deformities, postoperative (late onset) neuro- logical deterioration can arise because of interference with the circulation to the spine leading to anterior spinal artery syndrome [26]. After anterior cervical fusion, recurrentlaryngealnerveinjuryhas been reported [15]. Dissection involving levels T1–2 can result in a postoperative Hor- ner syndrome caused by injury to the stellate ganglion [8]. A case of bilateral phrenic nerve palsy as a complication of anterior decompression and fusion has been described [10]. After iliac crest bone grafting, one has to be aware of possi- ble neurological deficits involving the lateral femoral cutaneous, ilioinguinal and superior cluneal nerves [19]. Postoperative Care and Pain Management Chapter 16 419 Gastrointestinal Function Postoperative paralytic bowel dysfunction can be ameliorated by thoracic epidural analgesia Intraoperative irritation of sympathetic splanchnic nerves causes postoperative paralytic bowel dysfunction, which can be made worse by activation of the sym- pathetic system due to pain and the large amounts of opioids necessary for suffi- cient analgesia. After major spinal surgery, a more rapid recovery of bowel func- tion has been documented if postoperative analgesia is performed through a tho- racic epidural catheter [2, 3]. Thromboembolic Prophylaxis Low-molecular-weight heparins prevent deep vein thrombosis and thrombo- embolic complications Although deep vein thrombosis and thromboembolic complications occur after spinal surgery at a lower rate compared to other orthopedic procedures, they can contribute disproportionately to morbidity and mortality [7]. Patients undergo- ing spinal surgery may be at increased risk of thromboembolic disease as a result of prolonged surgery, prone positioning, malignancy, and extended periods of postoperative recumbency. Appropriate preventive measures include the use of compressive stockings, early mobilization and prophylactic administration of low-molecular-weight heparins [22]. Postoperative Pain Management Consequences of Pain Postoperative pain after spinal surgery can be severe Pain management can be a major challenge after spinal surgery (see Chap- ter 5 ). The alleviation of postoperative pain is primarily provided for hu- manitarian reasons, but also to reduce nociception-induced responses, which may adversely influence organ functioning and contribute to morbidity [16]. A common feature shared by all surgical patients is the widespread changes in several biological cascade systems, including a predominance of catabolic hormones, activation of cytokines, complement arachidonic acid metabolites, nitric oxide, and free oxygen radicals, all of which may secondarily lead to organ dysfunction and morbidity. Pain may obviously be considered as another neurophysiological response to surgery but with its own secondary effects on biological functions. Pain amplifies the metabolic response, auto- nomic reflexes, ileus, and nausea and delays mobilization and feeding. Effec- tive treatment of postoperative pain, therefore, results in modification of the biological response to surgery, but the extent of modification is dependent on the choice of analgesic technique [18]. Patients undergoing spinal surgery, particularly through a thoracic ap- proach, may have a large incision extending over several dermatomes. Many patients have preexisting chronic pain conditions, may be cognitively im- paired (some have neuromuscular disorders), or may be very young. A multi- modal approach to analgesia (see Chapter 5 ) is recommended [17], using an appropriate combination of ( Table 2 ): Table 2. Multimodal analgesia acetaminophen (paracetamol) non-selective cyclooxygenase inhibitors COX-2 inhibitors opioids local anesthetics 2 -agonists ketamine regional anesthesia techniques A multimodal approach to analgesia facilitates ambula- tion and respiratory care Adequate analgesia facilitates early ambulation and aggressive respiratory care, which are important to decrease patient morbidity postoperatively. 420 Section Peri- and Postoperative Management Non-narcotics Acetaminophen and NSAIDs exhibit an opioid-sparing effect Non-opioid analgesics (acetaminophen) and non-steroidal anti-inflammatory drugs (NSAIDs) play a central role in the management of postoperative pain, since they have shown an opioid-sparing effect, but there is little evidence for an additive analgesic effect of two non-opioid analgesics. Acetaminophen should not begiveninpatientswith impaired liver function Acetaminophen can be part of a multimodal pain therapy without great risk, with the exception of patients with impaired liver function. It has an additional antipyretic potency. Non-steroidal Drugs Both non-selective cyclooxygenase inhibitors (NSAIDs) and the selective cycloo- xygenase-2 (COX-2) inhibitors have been used successfully for pain therapy in different orthopedic surgical contexts, including spinal surgery [21]. The use of non-selective NSAIDs may increase bleeding time by 30±35%, cause gastritis and be associated with acute renal failure, particularly in the pres- ence of hypovolemia and hypotension. COX-2 inhibitors have an analgesic effi- cacy comparable to non-selective NSAIDs, but are associated with an absence of antiplatelet activity and reduced gastrointestinal side effects. However, because both COX-1 and COX-2 are present in the kidney, COX-2 inhibitors require the same caution with their use regarding renal toxicity as non-selective NSAIDs, and special caution is warranted not to further decrease an already impaired renal function, especially in diabetic patients under concomitant ACE-inhibitor therapy for blood pressure control. The influence of these drugs on bone healing and bone-tendon healing is con- troversial [12]. The results of experimental and animal studies with long-term administration probably cannot be transferred to the perioperative setting when these drugs are prescribed for a limited duration of some days. Non-selective NSAIDs and selective COX-2 inhibitors should be used for a short postoperative period The concerns regarding increased cardiac risk following the long-term administration of COX-2 inhibitors have to date only been demonstrated for rofecoxib, which therefore has been withdrawn from the market. In our hands, the use of NSAIDs and COX-2 inhibitors for up to 10 days after surgery has become a standard of (our) care and does not seem to have noticeable side effects. Opioids Subcutaneous or intramus- cular opioid administration exhibit a poorly predictable time course for the maximum analgesic effect Opioids can be administered by different routes. The use of parenteral opioids has been the mainstay of analgesia for all patients undergoing spinal surgery. Subcutaneous or intramuscular administration has the major drawback of uncontrolled absorption and distribution, unpredictable time to maximal effect and unpredictable duration of action. Because of the aspects mentioned, intravenous administration [con tinuous infusion and p atient-controlled anal- gesia (PCA) devices with or without background infusions] should be pre- ferred. Opioids can also be given epidurally or intrathecally. The thecal sac is readily accessible during spinal surgical procedures and intrathecal medication can be injected with technical ease before wound closure. Early reports of the use of intrathecal opioids for analgesia in children after spinal surgery and other major surgeries have suggested that the use of morphine 20–30 mg/kg is associated with excellent analgesia for up to 24 h. More recent studies suggest the optimum dose of morphine to be 2±5 mg/kg, which provides a comparable analgesia for 24 h but with fewer side effects [5, 13]. Postoperative Care and Pain Management Chapter 16 421 Independently of the way they are administered, the use of opioids is associated with side effects such as: respiratory depression nausea and vomiting pruritus urinary retention sedation ileus Opioid-related side-effects are independent of the route they are administered The latter gastrointestinal side-effect may be especially disadvantageous after major spinal surgery, when some degree of paralytic ileus is common. There is the possibility of reducing postoperative parenteral opioid consump- tion by the administration of an oral slow release opioid formula, which is intro- duced preoperatively [4]. Patients with cancer or other patients who have received long-term opioids preoperatively by different routes (e.g., enteral, trans- dermal) must be assumed to have acquired a degree of opioid tolerance and these drugs should also be restarted as early as possible postoperatively. Local Anesthetics Administration of local anesthetics through epidural catheters allows for excellent pain control The use of local anesthetic agents alone or in combination with opioids by the epidural route after spinal surgery has been described [27]. For scoliosis correc- tion surgery with a dorsal or ventrodorsal approach, the use of continuous epidu- ral analgesia with plain local anesthetic solution through one or two epidural catheters placed intraoperatively by the surgeon has been shown to provide effi- cient postoperative pain control with early recovery of bowel function, few side- effects and a high patient satisfaction [2, 3]. Epidural analgesia with local anesthetic agents can make neurological assess- ment difficult. Since the early postoperative period is critical for the appearance of a postoperative neurological deficit, there is the possibility of performing anal- gesia with a potent opioid (e.g., remifentanil) up to the first postoperative morn- ing. After a thorough assessment of the neurological status, epidural analgesia canbeintroduced.Theadministrationrateofthelocalanestheticcanbeguided according to the level of motor and sensory blockade [2, 3]. Continuous administration of local anesthetics to the iliac crest after bone grafting relieves donor site pain The continuous administration of local anesthetics to the iliac crest after bone grafting through a catheter placed by the surgeon at the end of the procedure is another new indication for these drugs [1]. N-Methyl-D-aspartate Antagonists Low-dose ketamine is helpful for acute postoperative pain TheroleoftheN-methyl-D-aspartate (NMDA) receptor in the processing of noci- ceptive input has led naturally to renewed clinical interest in NMDA receptor antagonists such as ketamine. It is a well-known general anesthetic and short- acting analgesic which has been in use for almost three decades. The efficacy of low-dose ketamine in the management of acute postoperative pain when admin- istered alone or in conjunction with other agents via the oral, intramuscular, sub- cutaneous, intravenous or epidural routes has been described and evidence sug- gests that low-dose ketamine may play an important role in postoperative pain management when used as an adjunct to local anesthetics, opioids or other anal- gesic agents [24]. Low-dose ketamine is defined as a bolus dose of less than 2 mg/ kg body weight when given intramuscularly or less than 1 mg/kg body weight when administered via the intravenous or epidural route. For continuous i.v. administration, low-dose ketamine is defined as a rate of at most 20 μg/kg body weight per minute. 422 Section Peri- and Postoperative Management Ketamine may provide clinicians with a tool to improve postoperative pain man- agement and to reduce postoperative opioid consumption and consecutively opi- oid-related adverse effects. The S-enantiomer of this drug, which is not available in all countries, has about a two times increased potency with a preferable side- effect profile. Recapitulation Postoperative care. Patients for spinal surgery often have significant comorbidities, and surgery imposes further stresses of blood loss, mass transfusion, coa- gulopathy, hypothermia, impaired pulmonary func- tion and acute postoperative pain. Perioperative tachycardia has to be treated since it is often com- bined with ischemia, which increases the risk of pe- rioperative myocardiac infarction.Intensivepost- operative insulin therapy can reduce mortality. The need for postoperative ventilation is suggested by patient and surgical factors, but most spinal surgery patients can be extubated shortly after the proce- dure or need artificial ventilation only for a few hours. Aggressive postoperative pulmonary care helps to avoid atelectasis and pneumonia. Monitor- ing of blood pressure, urine output, central venous pressure, chest tubes and wound drainage is essen- tial. Neurological assessment to detect neurologi- cal deterioration is important, and immediate inves- tigation (and when available magnetic resonance imaging) should follow any suspicious finding. In- traoperative irritation of sympathetic splanchnic nerves, activation of the sympathetic system due to pain and large amounts of opioids cause postopera- tive paralytic bowel dysfunction. Preventive mea- sures for thromboembolic disease include the ad- ministration of low-molecular-weight heparins. Postoperative pain management. A multimodal approach to analgesia is recommended since ade- quate analgesia allows early ambulation and ag- gressive respiratory care. Non-opioid analgesics haveshownanopioid-sparingeffect.Acetamino- phen can be given without great risk. Non-selective NSAIDs cannot be recommended for intraoperative and early postoperative analgesia. COX-2 inhibitors have analgesic efficacy comparable to non-selective NSAIDs,butareassociatedwithanabsenceofanti- platelet activity and reduced gastrointestinal side effects, while requiring the same cautions regarding renal toxicity as non-selective NSAIDs. Opioids are potent analgesics and can be administered by dif- ferent routes. Intravenous administration (continu- ous infusion or patient-controlled) is preferred. In- dependently of the way they are administered, their use is associated with side effects such as respirato- ry depression, nausea and vomiting, pruritus, uri- nary retention, sedation, and gastrointestinal ileus. Continuous local anesthetic agents through the epidural route after spinal surgery have been shown to provide efficient postoperative pain control with early recovery of bowel function, few side effects and high patient satisfaction. Continuous local an- esthetic administration to the iliac crest after bone grafting is another new indication for these drugs. The efficacy and opioid-sparing effect of low-dose ketamine in the management of acute postopera- tive pain has been described. The S-enantiomer of this drug has an increased potency with a preferable side-effect profile. Key Articles van den Berghe G, Wouters P, Weekers F, Verwaest C, Bruyninckx F, Schetz M, Vlassela- ers D, Ferdinande P, Lauwers P, Bouillon R (2001) Intensive insulin therapy in the criti- cally ill patients. N Engl J Med 345:1359 – 67 It was proven for the first time in this prospective study of 1548 adults admitted to the surgical intensive care unit that intensive intravenous insulin therapy to maintain blood glucose at between 4.4 and 6.1 mmol/l can reduce mortality during intensive care and during hospital stay, decrease the incidence of infectious complications and shorten mechanical ventilation. Kehlet H (1997)Multimodalapproachtocontrolpostoperativepathophysiologyand rehabilitation. Br J Anaesth 78:606 – 17 The author demonstrates why no single technique or drug has been shown to eliminate postoperative morbidity and mortality, and why multimodal interventions may lead to a Postoperative Care and Pain Management Chapter 16 423 . often combined with ischemic episodes, and their treatment is mandatory because of the high mortality of perioperative myocardiac infarction ✔ Intensive insulin therapy can reduce morbidity and. ileus, and nausea and delays mobilization and feeding. Effec- tive treatment of postoperative pain, therefore, results in modification of the biological response to surgery, but the extent of modification. application of intraoperative monitoring during surgery for spinal deformity. Spine 24:2649–62 58. ParkChK(2000)Theeffectofpatientpositioningonintraabdominalpressureandblood loss in spinal surgery.