Anesthesia for spine 13มค66

ANESTHESIA FOR SPINE SURGERY R2 Itsarapong Vetchagama Advisor. Wantanee Kananon 1

OUTLINE Preoperative assessment Intraoperative management Positioning concerns Intraoperative neuromonitoring Management of bleeding Pain management 2

GENERAL INDICATION FOR SPINE SURGERY • Neurological dysfunction • Structural instability • Pathological lesion • Deformity • Pain 3

SPINAL CONDITION REQUIRING SPINAL SURGERY Intervertebral disc lesions Spondylolosthesis 4

SPINAL CONDITION REQUIRING SPINAL SURGERY Spinal stenosis scoliosis kyphosis Spinal tumor 5

SURGICAL PROCEDURE laminotomy laminectomy disectomy 6

Fusion and fixation SURGERY PROCEDURE instrumentation 7

PREOPERATIVE ASSESSMENT • GENERAL ASSESMENT • Full Neurological evaluation function and symptoms deficits associated spinal disorder • Muscular dystrophies maybe risk of postoperative aspiration • Level of injury and time elapsed since the insult are prediction of physiologic of cardiovascular and respiratory system intraoperatively • <3 weeks of injury spinal shock maybe still present • After 48 hrs after SCI succinylcholine should be avoid 8

PREOPERATIVE ASSESSMENT • Airway assessment • The potential for difficulty in airway management should always considered in patient with cervical and thoracic spine disease • Stability of the cervical spine • Restriction of movement due to disease or level of injury or equipment support • Mouth opening • The essential discussion preoperatively the stability of the spine with surgeon 9

PREOPERATIVE ASSESSMENT • Respiratory assessment • Any existing ventilation impairment • Any sign of pulmonary disease • Infection URI LRI asthma COPD • Level of deformity • Upper C-spine level surgery • Special deformity • Scoliosis • Kyphosis • ankylosis 10

PREOPERATIVE ASSESSMENT • Cardiovascular assessment • comprehensive review of the patient cardiovascular history • Hypertension • Diabetic mellitus • Congestive heart failure • Coronary artery disease • Basic renal function and liver function and rehabilitation nees to be considered 11

SUGGEST PREOPERATIVE INVESTIGATION Suggest minimal investigation Optional investigation Airway X rays Cervical spine lateral view CT scan Pulmonary with flextion/extension CVS CXR Spirometry ABG Plumorany function test ECG Echocardiogram Blood test CBC Additional as co-morbidity requirement Electrolyte renal function 12 PT/PTT Blood component

SPECIFIC PREOPERATIVE ASSESSMENT FOR DIFFERENT SPINE PROCEDURES • Procedures of the upper cervical levels • spine tumors • Genetic abnormality • cervical surgery on the middle and lower level • degenerative disease to decompress the spinal cord and nerve roots • the anterior approach of laryngeal • phrenic nerve damage 13

SPECIFIC PREOPERATIVE ASSESSMENT FOR DIFFERENT SPINE PROCEDURES • procedures at the thoracic level • Scoliosis • congenital defects idiopathic or neuromuscular • complex cases • preoperative assessment of pulmonary function • severe blood loss and massive transfusion • lumbar level • multilevel spinal fusion and instrumentation for more complex pathologies • truncal obesity • coronary artery disease • sleep apnea • metabolic syndrome 14

SPINAL TRAUMA • The initial SCI may be cause by mechanical injury • Following of the initial injury systemic inflammation, ischemia and excitotoxicity and progression of the neurological symptoms • If facial or cervical spine injury are present airway management can be particularly challenging • Manual in-line stabilization (MILS) • MILS can worsen laryngeal visualization • Video laryngoscope is reasonable alternative to conventional • Obiviously Fiberoptic intubation is often the safest approach in patient with cervical spine instability 15

SPINAL TRAUMA • Neuromuscular blockade • risk of hyperkalemia associate with depolarized neuromuscular blocking agent • SUCCINYLCHOLINE should be avoid after initial 48-72 hours following SCI • important challenge • patient with SCI is systemic hypotension • hemorrhage, hypovolemia. • neurogenic or spinal shock • bradycardia as well as vasodilation associate with loss of supraspinal sympathetic control • The American assocination of neurological surgeons (AANS) recommended systemic arterial pressure maintain greater than 90 mmHg for 5-7 day after SCI 16

INTRAOPERATIVE MANAGEMNET 17 • Airway management • common principles general anesthetics • standardized difficult airway algorithm • cervical myelopathy or instability, • maintaining a neutral neck position • video laryngoscopy • flexible fiberoptic equipment • in-line stabilization • Signifcant deformities ankylosing spondylitis • severely limited cervical mobility and mouth opening • awake fiberoptic intubation • preoperative tracheostomies

INTRAOPERATIVE MANAGEMNET • IV access and monitoring equipment • complex spine surgery, • significant blood loss is a frequent occurrence • multiple large bore peripheral cannulas • central venous access and Intraarterial monitoring as indication • all access should be planned at the beginning of the case 18

INTRAOPERATIVE MANAGEMENT • Choice of maintenance • general anesthesia is warranted for most complex spine cases • maintenance of general anesthesia • factors including hemodynamic stability • intraoperative neuromonitoring • a balanced anesthetic including volatile agent, propofol, opioids, and various intraoperative adjuncts can typically be utilized • total intravenous anesthesia (tiva) must be utilized to allow for neuromonitoring 19

POSITIONING CONCERNS • Prone position is the most use in spine surgery • The airway is usually secured via an endotracheal tube • The ETT should be disconnected during change position • Ventilation should be reestablished as rapidly as possible • Head is usually neutral position by use surgical pillow, horseshoe headset or headpin • Weight on bony facial prominences not soft tissue and not on the eyes • If motor-evoked potential are use tongue and bite block are check 20

POSITIONING CONCERNS Prone position • Legs on padded and slightly flex hip and knee • Arm on neutral position or outstretched above head with slignt flextion elbow and abduction not greater than 90 degrees • The prone position is the risk factor for postoperative visual loss (POVL) • When patient are in prone position weight should be disturb to the thoracic and bony pelvis abdomen should hang freely • Placement of bolsters beyond iliac crests can cause compression on femoral vessel and femoral nerve • Pulmonary function is better in the prone position because the lung volume and oxygenation are not adverse effects on lung mechanism 21

POSITIONING CONCERNS • Supine position with head traction in anterior approach to cervical spine • Sitting or lateral decubitus position occasionally 22

POSTOPERATIVE VISION LOSS Anterior or posterior ischemic of optic neuropathy retinal ischemia cortical blindness • Risk factor • Male • Obesity • Wilson frame • Greater blood loss • Lower percent colloid administration • Goal • Manage of reduce risk factor • Adequate fluid resuscitation • Reduce of perioperative blood loss • Maintain in neutral position and avoid 23

INTRAOPERATIVE NEUROMONITORING • Wake up test is used to assess the integrity of the spinal motor pathway and is performed by “lightening“ the depth of anesthesia sufficiently to allow the patient to follow commands • Anesthetic techniques • Volatile-based anesthesia • Propofol-based anesthesia 24

INTRAOPERATIVE NEUROMONITORING Wake up test • Disadvantages • Requires patients co-operation • risks falling and extubation • Requires practice • Prolong the duration of surgery • Provides information at the time of the wake-up only • Does not assess sensory pathways 25

INTRAOPERATIVE NEUROMONITORING • Historically the Wake-Up test was considered the gold standard for intraoperative neuromonitoring • SSEPs involve a stimulus at a peripheral nerve, which travels up through the neural pathways up to the cortex where the signal is recorded. an increase in the latency or a decrease in the amplitude can indicate pathologic change. • MEPs involve a transcranial stimulus, which then travels down motor pathways to the target musculature where amplitude and latency are then recorded • EMGs can be used to identify either surgical irritation of nerve roots or nerve roots at risk of postoperative 26

INTRAOPERATIVE NEUROMONITORING Sensory-evoked responses (SER) are electric CNS response to electric stimuli SERs are produce by stimulating a sensory system and recording the electric response at varies site along sensory pathway SER recording are two general types determined by distance of recording from generator near-field potential 3-4 cm from generator Far-field potential are record far from generator SERs technique cortical record probe place on the scalp subcortical and peripheral are place in standard anatomical location 27

INTRAOPERATIVE NEUROMONITORING Evoked potential all type are describer in terms of latency and amplitude Latency = time measure from the application of the stimulus to the onset or peak of the response Amplitude = the voltage from record response 28

INTRAOPERATIVE NEUROMONITORING SSEP are the most common recorded intraoperative because they are less influenced by change in anesthetic drug level The pathway is the large fiber sensory nerve -> dorsal root ganglion ->ipsilateral posterior column of spinal cord synapsing in the dorsal column nuclei 29

INTRAOPERATIVE NEUROMONITORING Motor-Evoked potentials (MEPs) stimulation electrode are place over motor cortex recording electrode usually placement at peripheral nerve or (the most) at innervated muscle MEP monitoring are quite invasive. Use much higher stimulus 30

INTRAOPERATIVE NEUROMONITORING Electromyography (EMG) intraoperative EMG response by cranial and peripheral motor nerve allow early detection of surgical induce nerve damage and assessment of lever of nerve function intraoperatively 31

INTRAOPERATIVE NEUROMONITORING 20XX PRESENTATION TITLE 32

EFFECT OF ANESTHETIC AGENT ON IONM • Volatile Agents • a dose-dependent decrease in amplitude and increase in latency of evoked responses • SSEP <1 minimum alveolar concentration • MEP is affected by even lower concentrations • EMG are resistant to inhalational agents • Intravenous Agents • SSEP signals are unaffected by high barbiturate doses • MEP signals are sensitive to barbiturates. • Ketamine can enhance SSEP and MEP responses • Etomidate can augment the amplitude of cortical SSEP recordings without affecting the peripheral evoked potentials or subcortical responses. • There are limited studies on the effect of dexmedetomidine on evoked potentials. • propofol suppresses SSEPs and MEPs in a dose-dependent manner but to a much smaller extent, allowing adequate measurements at commonly used clinical doses. • It is considered the anesthetic agent of choice to facilitate IOM, especially when MEP monitoring is used. 33

EFFECT OF ANESTHETIC AGENT ON IONM Muscle Relaxants If a muscle relaxant has to be used intraoperatively while monitoring MEP or EMG, the level of paralysis should be carefully controlled and monitored Neuromuscular blockade should be maintained at a stable and mild level throughout the monitoring period with a neuromuscular blocker infusion, aiming for not more than two twitches on train-of-four stimulation. 34

MINIMIZE BLOOD LOSS IN SPINE SURGERY 35

MINIMIZE BLOOD LOSS IN SPINE SURGERY • Preoperative Autologous Blood Transfusion and Erythropoietin • we recommend 2 steps. In patients considering PABD • hemoglobin (Hb) 3 to 4 weeks prior to surgery • anemic (Hb < 11 g/dL) should be dissuaded from PABD or optimized using erythropoietin and iron supplementation • Similarly, for those pursuing PABD that subsequently demonstrate signs of PABD-induced anemia • Food and Drug Administration (FDA) approval is only for those with perioperative hemoglobin levels between 10 and 13 g/dL who are unwilling to donate blood preoperatively 36

MINIMIZE BLOOD LOSS IN SPINE SURGERY Intraoperative blood loss management • Positioning • Appropriate surgical positioning is an underappreciated means of decreasing intraoperative blood loss. Two considerations include (1) the relative positions of the surgical site and right atrium • lumbar and lower thoracic spine, • Trendelenburg position can reduce pressure in IVC and decrease bleeding from the epidural and vertebral venous plexuses • Reverse Trendelenburg offers similar benefits in cervical procedure (2) the intra-abdominal pressure (IAP) • Conventional surgical tables elevate IAP, • congestion of the epidural venous plexus—a common source of bleeding. 37

MINIMIZE BLOOD LOSS IN SPINE SURGERY Intraoperative blood loss management • Normothermia • Maintaining core temperature at physiological levels has also been proposed to reduce blood loss by preventing hypothermia induced coagulopathy • Strategies to prevent hypothermia include • forced air warming • warm socks • warmed intravenous fluids • warmed irrigation fluids 38

MINIMIZE BLOOD LOSS IN SPINE SURGERY Hypotensive Anesthesia • The reported that maintaining a MAP of 65 mm Hg or less reduced blood loss in deformity cases by 33% • low MAPs can place the spinal cord at risk of infarction • Hypotensive anesthesia (MAP 70 mm Hg) may be best reserved for the approach and instrumentation, where bleeding risk is highest. 39

MINIMIZE BLOOD LOSS IN SPINE SURGERY Hypotensive Anesthesia • This recommendation is strongest for patients with increased risk of ischemic complications at baseline, such as those with peripheral vascular disease, a history of ischemic events (e.g., stroke), chronic renal failure, or uncontrolled diabetes mellitus Overall, we caution against the use of hypotensive anesthesia when there is risk of neurologic injury from poor perfusion 40

MINIMIZE BLOOD LOSS IN SPINE SURGERY Surgical approach • midline approach is the most common approach employed for posterior spine surgeries • During dissection, care is taken to remain in the avascular plane formed by the fascial sheaths of the 2 paraspinal muscular bundles • Electrocautery • a recent meta-analysis by Lan and colleagues suggested that the use of a bipolar sealer can reduce operative times, intraoperative blood loss, and transfusion rates 41

MINIMIZE BLOOD LOSS IN SPINE SURGERY antifibrinolytic agents • Tranexamix Acid (TXA) • A recent meta analysis of demonstrated a mean decrease in intraoperative blood loss of 229 mL • the most commonly used regimen employs a loading dose of 10 mg/kg and maintenance dosing of 1 to 2 mg/kg/h • Both TXA and EACA are powerful agents in minimizing blood loss compared with placebo controls. • Meta-analysis using either TXA or EACA for adults undergoing spinal fusionfound antifibrinolytic use to reduce intraoperative blood loss by a mean of 127 mL and postoperative blood loss by a mean of 95 mL 42

MINIMIZE BLOOD LOSS IN SPINE SURGERY Intraoperative Cell Salvage • A final intervention capable of minimizing the effect of blood loss during spine surgery is the use of intraoperative cell salvage (ICS). • ICS works by draining fluid and blood from the dissection cavity and filtering out clotting factors, platelets, and other debris to form an RBC-enriched unit that can then be returned to the patient 43

MINIMIZE BLOOD LOSS IN SPINE SURGERY Postoperative Drain • Postoperative “hidden” blood loss may also substantially contribute to postoperative anemia and the need for transfusion • prior studies suggesting that these losses may account for 40% to 47% of total blood loss • The use of closed suction drains postoperatively is one intervention that has been suggested to decrease these hidden losses. 44

PAIN MANAGEMENT • Multimodal analgesia : combined analgesics with different model or site of action can improve analgesia reduce opioid requirement “opioid sparing effect” and the therapy reduce adverse effect of opioids in the postoperative period • Preventive analgesia : preoperative, intraoperative, postoperative preriod • Minimize opioid consumption by optimize non-opioid analgesics • Use evidence-base,procedure-specific pain management guidelines, there available 45

PAIN MANAGEMENT Pre-operative and intra-operative interventions • Oral or IV paracetamol (Grade D) • Oral or IV NSAIDs/COX-2 specific inhibitors (Grade A) • IV ketamine infusion (Grade A) Postoperative interventions • Epidural analgesia with local anaesthetics with or without opioids (Grade B) • Oral or IV paracetamol (Grade D) • Oral or IV NSAIDs/COX-2 specific inhibitors (Grade A) • Opioids as rescue medication (Grade D) 46

REFERENCE • Miller's anesthesia byMichael A. Gropper , Ronald D. Miller • Singleton M, Ghisi D, Memtsoudis S. Perioperative management in complex spine surgery. Minerva Anestesiol. 2022 May • Introduction to Intraoperative Neurophysiological Monitoring for Anaesthetists G E N E R A L A N A E S T H E S I A Tutorial 397 www..wfsahq.org • Global Spine Journal 2020, Vol. 10(1S) 71S-83S ª The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions • Acute Pain Management: Scientific Evidence 5th edition • Prospect recommendations for complex spine surgery 47

THANK YOU 48