What the Anesthesiologist Should Know before the Operative Procedure?
Total knee arthroplasty (TKA) is considered an elective procedure. It typically involves the use of a thigh tourniquet, and consequently expected intra operative blood loss is minimal. Blood loss, however, can be considerable in the Post Anesthesia Care Unit (PACU) if the case is a simultaneous bilateral TKA. The surgery itself carries an intermediate peri-operative risk of complication.
1. What is the urgency of the surgery?
What is the risk of delay in order to obtain additional preoperative information?
TKA is considered to be a completely elective procedure and a full investigation of the patient’s health status should be obtained prior to proceeding with the surgery.
Emergent:TKA is not an emergent surgery.
Urgent:TKA is not an urgent surgery.
Elective:Typically, this type of procedure is elective in nature, and the patient must be optimized for surgery.
2. Preoperative evaluation
Osteoarthritis, rheumatoid arthritis (RA), and traumatic arthritis are usually the major causes for knee joint degeneration that is severe enough to warrant this procedure. Obesity can accelerate the degeneration process and comes with a host of medical issues, including hypertension, diabetes, and obstructive sleep apnea (OSA). More specifically, one should always evaluate cardiac and respiratory comorbidities in these patients.
Medically unstable conditions warranting further evaluation include: recent myocardial infarction, unstable angina, unstable dysrhythmia, hypertension with evidence of end organ damage, poorly controlled diabetes, chronic obstructive airway disease that is not well optimized, active pulmonary infection, and uninvestigated anemia or thrombocytopenia.
Delaying surgery may be indicated if: any of the above conditions are present and are not controlled, investigated, or optimized.
3. What are the implications of co-existing disease on peri-operative care?
b. Cardiovascular system
Patients with a history of chest pain that has not been investigated should be referred to a cardiologist for further evaluation. These conditions should be optimized prior to elective surgery and evaluated according to the ACC/AHA guidelines.
Baseline coronary artery disease or cardiac dysfunction
All patients should undergo a thorough history and physical examination prior to surgery to assess the severity of their disease. If the patient has had a percutaneous intracoronary stent (within 12 months prior to surgery), a perioperative plan should be devised between the surgeon, the cardiologist, and the anesthesiologist to determine if the patient should remain on dual antiplatelet therapy (aspirin and or clopidogrel) or to create an appropriate “bridging” plan. If the patient is on beta-blockers or aspirin, these drugs should be continued on the day of surgery. Most antihypertensive drugs may also be continued on the day of surgery, save for angiotensin-converting enzyme inhibitors and angiotensin receptor blockers.
A history of moderate to severe reactive airway disease would favor a technique that did not involve general anesthesia.
Chronic Obstructive Pulmonary Disease (COPD)
Perioperative Evaluation:A thorough history and physical examination will be the best evaluation for severity of disease (admission to the hospital, oxygen requirements at home, or steroid use). Pulmonary function tests and arterial blood gas may also be helpful in evaluating the patient’s disease state.
Perioperative Risk Reduction: Continuing the patient’s home medication on the day of surgery and avoiding instrumentation of the airway will reduce the likelihood of postoperative pulmonary complication.
Reactive airway disease (Asthma)
Perioperative Evaluation:Similar to COPD, a thorough history and physical will identify the severity of the patient’s disease (number of hospitalizations, active wheezing, steroid use).
Perioperative Risk Reduction:Similar to COPD, an anesthetic technique that avoids general anesthesia would be the preferred method.
Perioperative Evaluation:Patients officially diagnosed with OSA will be categorized by their severity. A thorough history from the patient can elicit this information as well as their compliance with their Continuous Positive Airway Pressure (CPAP) machine at home.
Perioperative Risk Reduction:Any anesthetic technique that does not secure the patient’s airway will risk obstruction from the patient should they become sedated. Vigilance in titrating their sedation during the course of the procedure to keep their airway patent will be necessary to prevent any intraoperative complications. Also, respiratory therapy will need to be consulted postoperatively when the patient is discharged from the PACU, as they will be in a less monitored setting while receiving intravenous opioid therapy for their analgesic needs, which may increase the risk of respiratory depression and airway obstruction.
Perioperative Evaluation:In patients with end-stage renal disease, electrolytes should be evaluated prior to the procedure to see if hemodialysis is needed to correct any abnormalities. Perioperative medication dosing should consider current estimated creatinine clearance.
Patients with liver disease will need coagulation laboratory results prior to surgery to ensure that central neuraxial anesthesia can safely be performed without increased risk of spinal hematoma.
In patients with a history of severe gastroesophageal reflux disease, either a central neuraxial technique with mild sedation or a general endotracheal anesthetic with a rapid sequence induction and intubation should be advocated.
Perioperative Risk Reduction:Patients with severe renal disease that is causing electrolyte abnormalities will need suitable corrections with hemodialysis prior to surgery. Nephrology consultation should also be involved in the patient’s postoperative care to ensure continued optimized medical care.
Severe liver disease resulting in coagulation disorder may need to be corrected prior to surgery.
Neurologic disorders are extremely variable in nature, and have important implications in the ultimate selection of anesthetic technique.
Perioperative Evaluation:Acute onset of new neurological deficits should be assessed prior to the procedure, requiring a full history and physical examination. A neurology consultation may be warranted, and deferring the elective procedure until such time as these issues can be evaluated and/or stabilized is absolutely indicated.
Perioperative Risk Reduction:As TKA is an elective procedure, any acute neurologic changes should be fully investigated before proceeding with the surgery.
Perioperative Evaluation:As part of the complete history and physical examination, recent exacerbations of disease states or chronic neuropathies should be evaluated.
Perioperative Risk Reduction:Chronic medications should be continued on the day of surgery. Also, dependent upon the chronic neuropathy, both central neuraxial and peripheral perineural analgesia should be evaluated to determine if suitable for the patient.
Perioperative Evaluation:Complete history and physical examination should look for a history of diabetes (common in obese patients), thyroid disorders, or adrenal dysfunction.
Perioperative Risk Reduction:In diabetes mellitus patients, the patient’s blood glucose should be evaluated on the morning of surgery. Oral hypoglycemic agents should not be continued on the day of surgery. If the patient is taking insulin, a reduction in their usual dose should occur due to their NPO status. These patients generally resume normal diets on their first postoperative day and should return to their pre-operative regimen, recognizing that the state of surgery may create elevated glucose levels, which could have a deleterious effect on wound healing.
Patients with either thyroid or adrenal dysfunction should be stabilized appropriately prior to surgery, which may potentially require an endocrine consultation.
g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)
Perioperative Evaluation: Rheumatoid arthritis and obesity are both implicated in the degeneration process leading to total knee arthroplasty. A thorough examination of the airway in both patient subgroups is necessary.
Perioperative Risk Reduction: In the case of patients with rheumatoid arthritis, cervical spine films can be obtained if atlantoaxial subluxation is suspected. A regional anesthetic technique is preferred for these patients, as securing the airway can be difficult, at times requiring awake fiberoptic intubation. In the case of obese patients, regional techniques are possible but may be more challenging. Sedation also becomes challenging, as redundant oropharyngeal soft tissues make them prone to airway obstruction.
4. What are the patient’s medications and how should they be managed in the perioperative period?
Patients may be on a variety of medications. It is important to review the medications to see which will be safe to continue in the perioperative period based on the anesthetic techniques employed.
h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?
Due to the high risk of potential DVT or PE postoperatively, an anticoagulation plan will be in place prior to surgery. There are numerous options available to the patient, which will affect the use of a central neuraxial anesthetic technique.
NSAIDs are not a contraindication for neuraxial anesthesia. The ACCP Anticoagulation Guidelines must be consulted if the anesthesiologist intends to employ a central neuraxial technique. Generally, because of the elective nature of the procedure, patients will not be on dual antiplatelet therapy at the time of the operation, but a “bridging” therapy may be in place.
i. What should be recommended with regard to continuation of medications taken chronically?
Cardiac: continue aspirin and beta-blockers. Cease angiotensin-converting enzyme inhibitors and angiotensin receptor blockers prior to surgery.
Pulmonary: continue all medications prior to surgery.
Renal: continue all medications prior to surgery.
Neurologic: continue all medications prior to surgery.
Anti-platelet: aspirin is safe to continue prior to surgery for any method of anesthesia employed. Other antiplatelet modalities (i.e. clopidogrel) will usually have been terminated prior to this type of procedure due to its elective nature. However, if after a consultation with both the cardiologist and orthopedic surgeon, it has been deemed that this is a mandatory therapy, a “bridging” therapy plan might be in place. This will affect the choice of regional anesthesia techniques.
Psychiatric: continue all medications preoperatively. Lithium is a consideration if a general anesthetic is employed, but usually regional anesthesia is preferred for this type of surgery.
Blood conservation: Anti-fibrinolytic therapy (either systemic and/or topical) with tranexamic acid (TXA) has been consistently shown to decrease perioperative blood loss and more importantly, decrease perioperative allogeneic red blood cell transfusion requirements. Due to the overwhelming evidence basis for its efficacy, the perioperative administration of TXA should be considered for all TKA procedures (in the absence of contraindications that may potentially increase the risk of postoperative VTE).
j. How To modify care for patients with known drug allergies –
Avoid medications that the patient is allergic to. Preoperative multimodal analgesia is common for this type of surgery. Sulfa allergy should not be considered a contraindication to utilizing celecoxib as part of a perioperative oral multimodal analgesic regimen.
k. Latex allergy- If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.
The OR staff must be aware of the patient’s latex allergy.
l. Does the patient have any antibiotic allergies- – Common antibiotic allergies and alternative antibiotics]
Antibiotics are required prior to incision in every TKA. If the patient is allergic to a typical antibiotic used for this procedure, the severity of the allergy must be determined and possible alternatives, such as vancomycin or clindamycin, discussed with surgical colleagues. Administration of vancomycin should take into consideration the time needed to administer the full perioperative dose required prior to surgical incision.
m. Does the patient have a history of allergy (or adverse effect) to anesthesia?
i. Malignant hyperthermia (MH)
Documented- avoid all triggering agents such as succinylcholine and inhalational anesthetic agents (ensure that both are removed from the OR and that the machine has been prepared appropriately)
Proposed general anesthetic plan: Total intravenous anesthetic with non-depolarizing muscle relaxant
Insure MH cart available
Family history or risk factors for MH: A thorough history should determine the patient’s risk for this condition. If it is determined that the patient is at high risk for acquiring MH intraoperatively, then a nontriggering general anesthetic technique should be utilized. A regional technique is the best anesthetic choice in this case.
ii. Local anesthetics/ muscle relaxants
There are two types of local anesthetics: esters and amides. Most allergies associated with local anesthetic agents are to esters because of metabolite (para-aminobenzoic acid). Amide allergies are exceedingly rare. A thorough patient history can elucidate what the reaction was and what type of local anesthetic was used. If the patient is a poor historian, avoidance of regional anesthesia may be necessary (provided old records cannot be obtained). If the patient has allergies to neuromuscular blocking agents (the most agents associated with anaphylaxis include succinylcholine or rocuronium), alternative neuromuscular blocking agents (such as cistracurium) should be utilized, or alternatively a central neuraxial anesthetic technique should be used.
5. What laboratory tests should be obtained and has everything been reviewed?
There are no specific laboratory tests recommended for patients undergoing TKA. Preoperative testing will depend on the patient’s review of systems, co-existing disease, and medications.
Hemoglobin levels: Ensure that this is optimized prior to the procedure in patients with anemia or severe cardiac disease.
Electrolytes: Ensure that patients with electrolyte disturbances are normalized prior to surgery and if renal dysfunction warrants adjustment dosing of medications intraoperatively.
Coagulation panel: Ensure the patient does not have any significant abnormalities of either primary and/or secondary hemostasis prior to the consideration of any regional technique.
Imaging: No specific imaging required.
Other tests: Availability of packed red cells may be necessary for bilateral TKA surgery, as blood loss is significant.
Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?
There are several anesthetic techniques that can be employed for this procedure, including neuraxial anesthesia with or without peripheral nerve block, general anesthesia with or without peripheral nerve block, and a combination of peripheral nerve blocks only. The knee itself is innervated, in most cases, by the femoral and sciatic nerves, with a small minority of patients also having some innervation from the obturator nerve.
a. Regional anesthesia
Options include epidural, spinal, femoral nerve block, sciatic nerve block, lumbar plexus nerve block, and high volume local infiltration by the surgeon.
1. Neuraxial (Epidural/Spinal)
Benefits: Reliable and simple technique that avoids general anesthesia. The advantage of epidural over spinal is that the block duration may be extended with an epidural catheter if an extended surgical duration is expected (revision TKA or sequential bilateral TKA performed by a single surgeon). There is substantial epidemiological data that central neuraxial anesthesia significantly decreases the incidence of perioperative complications and surgical site infection compared to general anesthesia.
Drawbacks: Risk for postdural puncture headache and a more challenging technique in obese patients.
Issues: Not suitable for patients who have uncorrected coagulation disorders or who are on anticoagulation therapy (not including monotherapy with aspirin). If epidural anesthesia is continued postoperatively, then the timing of removal must coincide with American Society of Regional Anesthesia (ASRA) Guidelines to reduce the risk of epidural hematoma. This generally means removal on the first post-operative day.
2. Peripheral Nerve Block
Benefits: Reduce postoperative pain, reduced incidence of nausea, reduced length of hospital stay.
Drawbacks: Requires some degree of technical expertise. Quadriceps weakness (femoral, lumbar plexus) may predispose patient to falls.
Issues: Most peripheral nerve blocks are safe in patients who have coagulation disorders or who are on anti platelet therapy, save for deeper tissue blocks like the lumbar plexus nerve block. For TKA, femoral nerve block (FNB) and lumbar plexus nerve block (LPNB) have been shown to provide similar levels of postoperative analgesia. The difference between these two techniques is that the lumbar plexus block requires a higher level of expertise and has the potential for more complications than the femoral nerve block. Finally, when using either a FNB or LPNB, motor weakness of the quadriceps muscles is a concern for the recovery of the patient, as they may have a greater risk of suffering a fall and will be limited in the scope of their physical rehabilitation. This last issue has become a concern for many orthopedic surgeons.
There has been a significant shift away from femoral nerve blocks due to concerns of quadriceps motor block associated weakness. Concerns related to quadriceps weakness are primarily a possible contribution to an increased risk of falls, as well as a delaying initiation of active ambulation. Due to the concerns regarding quadriceps weakness, adductor canal block (single-injection or continuous techniques) has become the predominant postoperative regional anesthetic-analgesic technique for TKA. Current evidence supports that adductor canal block provides analgesia that is noninferior and consistently results in significantly less quadriceps motor block compared to femoral nerve block.
3. Local Infiltration
High volume local anesthetic infiltration (LAI) into the subcutaneous and periarticular tissues surrounding the joint capsule is a rather simple technique that should be routinely performed by the surgical team to reduce postoperative pain. Local anesthetic infiltration analgesia has become an integral part of multimodal perioperative analgesia.
b. General Anesthesia
Benefits: This is a simple technique that has a near 100% success rate and has no contraindications in the setting alterations of primary or secondary hemostasis.
Drawbacks: Longer OR and PACU recovery times, increased incidence of nausea/vomiting (which may continue post-operatively if systemic opioids alone are relied on for post-op analgesia), longer hospital length of stay.
Other issues: In some patient populations (RAD), instrumentation of the airway will result in more postoperative complications. Also, patients with rheumatoid arthritis might be challenging, given the potential of atlantoaxial instability.
Airway concerns: This is dependent upon the patient prior history and identified risk factors for possible difficult intubation and/or difficult mask ventilation.
c. Monitored Anesthesia Care
Benefits: This is only possible through neuraxial anesthesia or a combination of peripheral nerve blocks. See Regional Anesthesia above.
Drawbacks: See Regional Anesthesia above.
Other Issues: See Regional Anesthesia above.
6. What is the author’s preferred method of anesthesia technique and why?
The author’s preferred technique is a combination of oral multimodal analgesia (typically consisting of celecoxib, gabapentin, and acetaminophen), continuous adductor canal blockade, and spinal anesthesia. A multi-faceted approach to TKA is often necessary given the intensity of postoperative pain. Using PO multimodal analgesics prior to surgery and continued postoperatively is a very simple but efficacious way of reducing opioid consumption postoperatively.
Recent data has demonstrated that adductor canal block has been shown to not only reduce postoperative opioid consumption and postoperative pain, but also facilitates more rapid ambulation. Finally, the avoidance of general anesthesia through the use of a neuraxial technique reduces recovery time and the incidence of surgical site infections.
a. What prophylactic antibiotics should be administered?
Cefazolin 1-3 g IV is the preferred antibiotic for TKA. However, if the patient has significant reactions (anaphylaxis and or airway edema) to penicillin, then clindamycin or vancomycin should be employed. Finally, if the patient has a known history of methicillin-resistant staphylococcus aureus (MRSA) infection, vancomycin should be used.
b. What do I need to know about the surgical technique to optimize my anesthetic care?
Because of the use of a thigh tourniquet over the course of the operation, when it is deflated, there may transient hypotension and hypercarbia (especially if both tourniquets are deflated simultaneously with bilateral TKA). This should be treated over the short-term, until the locally-mediated inflammatory cytokines can be reabsorbed systemically. If surgical hemostasis is inadequate, blood loss can become substantial in the PACU, necessitating volume resuscitation.
c. What can I do intraoperatively to assist the surgeon and optimize patient care?
If a regional technique has been employed, the limb being operated on is completely insensate to the surgical trauma. At this point it is a matter of carefully titrating your sedation to the preference of the patient while maintaining adequate monitoring. If the patient is having a general anesthetic, the usual ASA monitoring is required.
d. What are the most common intraoperative complications and how can they be avoided/treated?
Prioritize them by urgency.
Cardiovascular collapse in the setting of local anesthetic systemic toxicity (LAST) can be seen following a peripheral nerve block due to severe bradycardia and hypotension in the setting of high spinal anesthesia. LAST is a rare complication, but should it occur, all resuscitation should include early administration of Intralipid™. Cardiovascular collapse associated with high spinal anesthesia should be aggressively treated with volume resuscitation and escalating doses of vasopressor therapy.
Pulmonary complications are unlikely to occur with regional anesthesia involving the lower extremities, but may occur in general anesthesia.
Unique to procedure: All neuraxial and peripheral nerve blocks carry the potential of LAST and nerve injury. Both are exceedingly rare, but may occur.
Clinical signs of LAST include: confusion, tinnitus, perioral numbness, seizures, and cardiovascular collapse. Early administration of Intralipid™ is recommended prior to or during cardiovascular collapse. Persistent nerve injury should be evaluated by a neurologist.
Finally, tourniquet pain is a complication of prolonged surgery whose definitive treatment is the deflation of the tourniquet itself.
b. If the patient is intubated, are there any special criteria for extubation?
If the patient has had a general anesthetic, then the usual criteria for extubation should apply.
c. Postoperative management
What analgesic modalities can I implement?
Postoperative pain is a large concern with these patients and can be managed with a combination of oral multimodal analgesic therapy, LAI, and adductor canal blockade.
What level bed acuity is appropriate?
A regular floor bed is appropriate for patients undergoing total knee arthroplasty, unless there are co-existing medical conditions that require escalation of care, in which case a more intensive setting may be appropriate (such as oxygenation monitoring in the presence of severe OSA).
What are common postoperative complications, and ways to prevent and treat them?
Common postoperative complications include hemarthrosis resulting in either thrombosis within the joint or anemia if a drain is placed. In the case of the thrombosis, pain can be severe enough for wound exploration. If bleeding persists despite repeated transfusion and correction of coagulation disorders, re-examination of the surgical site may also be necessary. Finally, deep vein thrombosis is a common complication for lower extremity joint replacement surgery and can be prevented by early ambulation and postoperative VTE prophylaxis (enoxaparin, heparin, warfarin).
What’s the Evidence?
Webb, CA, Mariano, ER. “Best multimodal analgesic protocol for total knee arthroplasty”. Pain Manag. vol. 5. 2015. pp. 185-96.
Seangleulur, A. “The efficacy of local infiltration analgesia in the early postoperative period after totally arthroplasty: a systematic review and meta-analysis”. Eur J Anaesthesiol. vol. 33. 2016. pp. 816-831.
Macrinici, GI. “Prospective, double-blind, randomized study to evaluate single injection adductor canal nerve block versus femoral nerve block: postoperative functional outcomes after total knee arthroplasty”. Reg Anesth Pain Med. vol. 42. 2017. pp. 00
Jiang, X, Wang, QQ, Wu, CA, Tian, W. “Analgesic efficacy of adductor canal block in total knee arthroplasty: a meta-analysis and systematic review”. Orthop Surg. vol. 8. 2016. pp. 294-300.
Sorenson, JK. “The isolated effect of adductor canal block on quadriceps femoris muscle strength after total knee arthroplasty: a triple-blinded, randomized, placebo-controlled trial with individual patient analysis”. Anesth Analg. vol. 122. 2016. pp. 553-8.
Liu, J. “Neuraxial anesthesia decreases postoperative systemic infection risk compared with general anesthesia in knee arthroplasty”. Anesth Analg. vol. 117. 2013. pp. 1010-6.
Chang, CC, Lin, HC, Lin, HW, Lin, HC. “Anesthetic management and surgical site infections in total hip or knee replacement: a population base study”. Anesthesiology. vol. 1134. 2010. pp. 279-84.
Alyshryda, S. “Tranexamic acid in total knee replacement: a systematic review and meta-analysis”. J Bone Joint Surg Br. vol. 93. 2011. pp. 1577-85.
Hallstrom, B. “The Michigan experience with the safety and effectiveness of tranexamic acid use in hip and knee arthroplasty”. J Bone Joint Surg Am. vol. 5. 2016. pp. 1646-1655.
Nielsen, CS. “Combined intra-articular and intravenous tranexamic acid reduces blood loss in totally arthroplasty: a randomized, double-blind, placebo-controlled trial”. J Bone J Surg Am. vol. 98. 2016. pp. 835-41.
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- What the Anesthesiologist Should Know before the Operative Procedure?
- 1. What is the urgency of the surgery?
- What is the risk of delay in order to obtain additional preoperative information?
- 2. Preoperative evaluation
- 3. What are the implications of co-existing disease on peri-operative care?
- b. Cardiovascular system
- c. Pulmonary
- d. Renal-GI:
- e. Neurologic:
- f. Endocrine:
- g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)
- 4. What are the patient’s medications and how should they be managed in the perioperative period?
- i. What should be recommended with regard to continuation of medications taken chronically?
- j. How To modify care for patients with known drug allergies -
- k. Latex allergy- If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.
- l. Does the patient have any antibiotic allergies- - Common antibiotic allergies and alternative antibiotics]
- m. Does the patient have a history of allergy (or adverse effect) to anesthesia?
- 5. What laboratory tests should be obtained and has everything been reviewed?
- 6. What is the author’s preferred method of anesthesia technique and why?
- a. What prophylactic antibiotics should be administered?
- b. What do I need to know about the surgical technique to optimize my anesthetic care?
- c. What can I do intraoperatively to assist the surgeon and optimize patient care?
- d. What are the most common intraoperative complications and how can they be avoided/treated?
- Cardiac complications
- a. Neurologic:
- b. If the patient is intubated, are there any special criteria for extubation?
- c. Postoperative management