What the Anesthesiologist Should Know before the Operative Procedure

The choice of which anesthetic technique to use, general or regional, is a key decision. This depends on many factors, including patient and surgeon preference, the anticipated duration of the procedure, the patient’s overall health, surgical site, and the positioning of the patient.

The planned patient positioning is of paramount importance and is usually the preference of the surgeon. Both the beach-chair and the lateral decubitus positions are used, and each have advantages and disadvantages.

If a regional technique is planned, it is important to know what area of the shoulder the procedure will focus on and where the surgeons will insert their instruments, as the skin of the shoulder is not entirely innervated by the brachial plexus. Local infiltration of portal sites by the surgeon, especially the posterior ones, is important.

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1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

The author has never seen an instance where a shoulder arthroscopy needed to be done on anything but an elective basis.

Emergent: If a true emergency arose and a shoulder arthroscopy was called for, one would most likely prefer to use general anesthesia with a rapid sequence induction and endotracheal intubation to limit the risk of aspiration.

Urgent: An urgent case would most likely allow enough time for proper emptying of the stomach so that a decision about which anesthetic technique to use could be based on factors others than the time of the patient’s last meal. Any additional preoperative information needed could be obtained during this time.

Elective: The vast majority of shoulder arthroscopies are done on an elective basis. There is usually no risk to the patient by delaying the case to obtain additional information.

2. Preoperative evaluation

End stage pulmonary disease

Careful preoperative evaluation is warranted, and part of the preoperative evaluation in these patients should be oriented towards deciding whether general or regional anesthesia offers the prospect for the better outcome. Choosing general anesthesia could result in prolonged postoperative ventilation, which could lead to ventilator-associated pneumonia. Most regional techniques can lead to respiratory difficulties, as they cause concomitant phrenic nerve paralysis, which may lead to intolerable respiratory depression in an already compromised patient.

Regional techniques that may decrease the incidence of phrenic nerve compromise are considered below. A careful history should be elicited, with particular attention to exercise tolerance and whether or not there is a reversible, brochospastic component to the pulmonary disease. Medications should be reviewed, as should an assessment of compliance with administration. Recent history of steroid utilization should be noted.

Physical exam should be directed at observing the pattern of breathing, to determine if accessory muscles are used. Careful auscultation should assess the presence of wheezes or rales, which are both potentially reversible. Primary care physicians may need to be consulted to see if the current assessment is consistent with the patient’s optimal state. Pulmonary function tests may help document a reversible component to the pulmonary disease or to assess whether the patient could tolerate the loss of tidal volume associated with a phrenic nerve paralysis.

If the likelihood of prolonged intubation and ventilation, either from general anesthesia or as a result of phrenic nerve paralysis, is significant, the patient may not be a candidate for this elective procedure. At a minimum, the patient and surgeon should be apprised of these risks.

Obstructive cardiomyopathy

It is appropriate to assess the degree of obstruction and the level of exercise tolerance. If there are limitations, a recent echocardiogram should be reviewed and consultation with the treating cardiologist might be appropriate. Medications should be reviewed, with a particular emphasis on beta-blockers and whether the patient seems appropriately beta-blocked. If not, delay and referral to the cardiologist for further therapy is warranted. Remember that these procedures can be associated with significant blood loss, which could lead to hypovolemia and to a potentially critical exacerbation of their obstruction.

Difficult airway

The evaluation of the difficult airway will influence the anesthetic choice somewhat. If the practitioner is confident in his or her regional skills, and if ample time is available to assess whether the block is working properly prior to the procedure, regional anesthetic techniques would be a reasonable option. If general is chosen or if the block is deemed inadequate, the practitioner should choose whatever difficult airway technique he or she has the greatest facility (fiberoptics, Glidescope etc.). It is imperative to avoid an inadequate block after the procedure has started.

Patient positioning

Beach-chair and lateral decubitus positions each present their own unique advantages and challenges. Most surgeons select one technique or the other. If the beach-chair is chosen, practitioners should search carefully for signs and symptoms of cerebral insufficiency or cerebrovascular disease. If present, a careful consideration of anesthetic technique should ensue. Some would choose a regional block with minimal sedation to continually assess gross cerebral function. If general anesthesia is chosen, a minimum tolerable blood pressure should be determined.

Local infection

Local infections at the site where a regional anesthetic technique would be administered are a contraindication to its use. Therefore, a decision to proceed with general anesthesia should be made.

Sepsis

Preoperative evaluation should assess the source of sepsis, adequacy of antibiotic administration, and the extent of hemodynamic compromise. General anesthesia in the floridly septic patient is problematic, but this type of elective surgery is not normally considered for these patients. Sepsis is a relative contraindication to neuraxial anesthesia, although there are data to suggest its safety if dural puncture is initiated after antibiotic administration (PUBMED:1581264, PUBMED:8896004).

Although rare, there have been reports of dural puncture and central nervous system complications with interscalene nerve blocks (PUBMED:19641049, PUBMED:7848937). Although data are extremely limited regarding sepsis and peripheral nerve blocks, the American Society for Regional Anesthesia (ASRA) guidelines should be applied to all regional anesthetic techniques.

Coagulation disorders

The type of coagulation disorder should be assessed through history and appropriate laboratory testing. Consultation with a hematologist might be appropriate. ASRA guideline should be followed; most practitioners feel that ultrasound- guided blocks are relatively safe in most patients with coagulation disorders. However, little or no data exist for peripheral nerve blocks of the shoulder in these patients. Vascular injuries with ultrasound-guided regional anesthetic techniques for the shoulder are rare (PUBMED:20686013).

There are case reports that demonstrate success using a peripheral nerve block in patients with coagulation problems: a patient with Hemophilia A successfully underwent foot surgery without bleeding complications (PUBMED:1932901) and a child undergoing a laparotomy for bowel resection with elevated PT and PTT values, but normal TEG ultrasound, received placement of bilateral paravertebral catheters without complication (PUBMED:21241416).

Antithrombotic medications

Patients receiving antithrombotic medications should not have them automatically discontinued preoperatively. Discussion with the surgeon and medical physician should address the relative benefits of continuing and discontinuing these medications. Elective surgery for those less than one year from placement of drug-eluting cardiac stents should be postponed if at all possible. In all patients with these stents, aspirin should be continued throughout the perioperative period.

There are no studies detailing the bleeding risks or frequencies following peripheral nerve blocks in anticoagulated patients. The few cases that are available show that significant blood loss and not neural injury are the most serious complications of non-neuraxial regional techniques in anticoagulated patients. The ASRA guidelines state that additional information is needed to make definitive recommendations. A conservative approach would be to apply the Consensus Statements on Neuraxial Anesthesia and Anticoagulation to peripheral nerve blocks, although this might be too restrictive (PUBMED:12772135).

Time from last meal

No solid foods should be ingested 6 to 8 hours prior to surgery to prevent risk of aspiration.

Ambulatory vs. inpatient

Most shoulder arthroscopy patients can be cared for on an ambulatory basis. Occasionally, patients require admission for observation of a preexisting medical condition or for intractable pain or nausea and vomiting.

Anesthetized patients

It is very controversial whether peripheral nerve block should be performed in the anesthetized patient. Approximately the same complication rate has been shown to exist for patients receiving interscalene blocks both in anesthetized and nonanesthetized patients (PUBMED:20708419). Benumof, however, has urged that interscalene block not be performed with the patient under general anesthesia.

Economics

Regional anesthesia using interscalene nerve block has been shown to be more cost effective than general anesthesia for shoulder arthroscopy (PUBMED:19586958). In addition, when compared to general anesthesia alone, regional anesthetic techniques for shoulder arthroscopy have been shown to allow patients to recover more quickly with fewer side effects and less post operative pain, especially when catheters and infusion pumps are used to provide extended analgesia (PUBMED:12651666, PUBMED:18299092, PUBMED:7727331, PUBMED:15851888, PUBMED:15271745).

  • Medically unstable conditions warranting further evaluation include: Any medically unstable condition would warrant further evaluation, since the vast majority of arthroscopic shoulder procedures are done on an elective basis.

  • Delaying surgery may be indicated if: any potentially reversible unstable medical condition is present.

3. What are the implications of co-existing disease on perioperative care?

N/A

b. Cardiovascular system

Acute/unstable conditions

Perioperative evaluation- Any acute or unstable condition as defined by the ACC/AHA guidelines (PUBMED:11973163) should be further evaluated.

Perioperative risk reduction strategies- Any unstable cardiac condition should be addressed and maximized. If an unstable condition cannot be improved upon, elective shoulder surgery should probably not be attempted.

Baseline coronary artery disease or cardiac dysfunction – Goals of management

Perioperative evaluation- The ACC/AHA guidelines for perioperative evaluation for noncardiac surgery state whether a patient with baseline coronary artery disease or cardiac dysfunction should be further evaluated after an initial history, physical exam, and electrocardiogram have been completed. In general, shoulder arthroscopy is considered low-risk surgery, although extensive procedures with significant blood loss may cross the line into intermediate risk. In any event, clinically stable patients with coronary disease or cardiac dysfunction can usually be successfully cared for.

Perioperative risk reduction strategies- Maintain cardiac and antihypertensive medications through the day of surgery. Physical exam should be directed toward assessing degree of beta-blockade (if appropriate), effectiveness of antihypertensive therapy, and the presence of new angina or heart failure. If any of these issues seem problematic or unclear, delay the surgery.

c. Pulmonary

COPD

Perioperative evaluation- A patient’s history and physical exam should include an evaluation of the patient’s functional capacity with activity and at rest. Spirometry may be useful, particularly to document the effect of bronchodilators and to establish the patient’s baseline condition. Arterial blood gas analysis is rarely indicated.

Perioperative risk reduction- In a patient suspected of having compromised pulmonary function, a trial of bronchodilator therapy is acceptable. As most shoulder arthroscopies are done on an elective basis, it is reasonable to postpone the case if the patient is currently experiencing an exacerbation of his or her condition.

If a decision is made to go forward with the surgery, a regional anesthetic technique may have advantages over general anesthesia. In an effort to preserve the patient’s respiratory function by not blocking the phrenic nerve, a combined suprascapular and axillary nerve block or combined suprascapular and infraclavicular plexus block are viable options (see below), although with these blocks some areas of the shoulder are not anesthetized. These areas include the acromioclavicular articulation, the subscapular muscle, and the anterior part of the glenohumeral articular capsule.

Only a limited number of procedures can be safely carried out with this type of anesthesia, including repair of supraspinatus muscle tendon lesions, excisions of intratendinous calcifications of the supraspinatus muscle, acromioplasties, bursectomies, bicepital tenotomies, and humeral head surgery (PUBMED:18514113, PUBMED:12606927).

Reactive airway disease (asthma)

Perioperative evaluation- A patient’s history and physical examination should focus on triggering factors, recent hospitalization, medication compliance, steroid dependence, and the identification of wheezing.

Perioperative risk reduction- Bronchodilator medications should be continued through the day of surgery. Administration of an “extra” dose of beta-agonist inhalers immediately prior to entering the OR may be appropriate.

d. Renal-GI:

Renal

The stability of the patient’s renal function should be assessed in those with known renal dysfunction. Those with significant deterioration should be postponed to assess the need for dialysis. Those receiving dialysis should probably be dialyzed the day before the procedure. The patient with end-stage renal disease on dialysis might benefit from a regional technique, unless he or she has a history of or laboratory data showing issues with coagulation.

GI

Patients with severe acid reflux uncontrolled with medication would probably benefit from a general anesthetic after rapid sequence induction.

e. Neurologic:

A preexisting neurological deficit, such as a neuropraxia, especially in the cervical spine or shoulder region, should be carefully documented. In these patients, a general anesthetic might be more appropriate than a regional anesthetic technique.

Those with a history of cerebrovascular accident or transient ischemic attack need to be carefully considered. The ability of the patient to tolerate the beach chair position and the intraoperative target blood pressure need to be considered. A risk-reduction strategy in these patients might be a regional technique with minimal sedation in order to use the patient’s sensorium as a monitor of cerebral perfusion.

f. Endocrine:

In the diabetic patient, preoperative blood sugar should be determined, as should compliance with medications. Using a regional anesthetic technique in a diabetic patient allows additional assessment of the patient for possible hypoglycemic episodes. Any patient with severe endocrine abnormalities, such as pheochromocytoma or thyrotoxicosis, should have his or her elective shoulder arthroscopy postponed until the issue is resolved.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Any patient with severe anxiety, claustrophobia, or fear of needles should not have regional anesthesia.

4. What are the patient's medications and how should they be managed in the perioperative period?

In general, most medications should be continued through the day of surgery. Diuretics may be held, and some centers advise that angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blocking (ARB) drugs be withheld to limit intraoperative hypotension. Antiplatelet drugs should be withheld for 7-14 days prior to surgery, depending on the agent, but only after consultation with the internist/cardiologist. In some situations, the risk/benefit ratio favors continuation.

Aspirin can usually be continued through surgery. Oral hypoglycemic agents should be withheld and attention paid to insulin administration strategies. One common approach is to administer half the usual insulin dose the morning of surgery and then monitor blood sugars perioperatively. Certain herbal therapies have been shown to increase the risk of bleeding, including garlic, ginko, and ginseng. These should be stopped 7 days, 36 hours, and 24 hours, respectively, prior to surgery (PUBMED:12772135).

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Patients undergoing shoulder arthroscopy will most likely be taking some type of pain medicine. Although NSAIDs exert an effect on platelet function, they do not appear to add any major risk to the development of spinal hematoma when used at the time of neuraxial anesthesia. It can be extrapolated that they would also be safe to use during peripheral nerve blocks.

COX-2 inhibitors do not cause significant platelet dysfunction, but may be procoagulant in the patients with coronary artery disease. In patients using narcotic pain medications, the effects of tolerance should be taken into consideration.

i. What should be recommended with regard to continuation of medications taken chronically?

  • Cardiac- continue, except for diuretics and possibly ACE inhibitors and ARBs

  • Pulmonary- continue

  • Renal- continue

  • Neurologic- continue

  • Anti-platelet- clopidogrel and ticlopidine should be discontinued 7 days and 10-14 days prior to surgery, respectively, with internist/cardiologist consultation. If the patient has had a drug-eluting stent inserted during the past 12 months, every attempt should be made to delay elective surgery.

  • Psychiatric- continue

j. How To modify care for patients with known allergies –

Avoid administration of agents known to be allergens.

k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

If the patient has a sensitivity or an anaphylactic reaction to latex, a latex-free environment should be provided for the patient.

l. Does the patient have any antibiotic allergies- [Tier 2- Common antibiotic allergies and alternative antibiotics]

Patients with certain antibiotic allergies should be given an alternative antibiotic, usually at the surgeon’s discretion.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia
Documented

avoid all trigger agents such as succinylcholine and inhalational agents:

  • Proposed general anesthetic plan: If a patient has had a documented episode of malignant hyperthermia, it would be advisable to pursue a regional anesthetic approach for the procedure.

  • Insure MH cart availability:Be sure staff is familiar with MH treatment protocols.

Family history or risk factors for MH

Consider regional anesthesia administration.

Local anesthetics/ muscle relaxants

If the patient has an allergy to local anesthetics, a plan to proceed with general anesthesia is warranted. If the patient has an allergy to muscle relaxants, a plan to proceed with regional anesthesia is warranted. If general anesthesia is planned, a muscle relaxant-free technique should be utilized.

5. What laboratory tests should be obtained and has everything been reviewed?

There are no specific laboratory tests that are indicated for this procedure. Preoperative testing should be guided by the history and physical exam. For example, the diabetic patient should have blood sugar assessed, and the patient with a history of bleeding or bruising could have platelets and coagulation status assessed.

There are no age criteria for testing, including for an electrocardiogram in the healthy patient. EKG may be warranted in patients with cardiac disease, but is usually unhelpful in the stable patient, except to have a baseline for later comparison.

Common laboratory normal values will be same for all procedures, with a difference by age and gender.

  • Hemoglobin levels: Males 13.5-16.5 (g/dL), Females12-15 (g/dL).

  • Electrolytes: Sodium 135-147 (mEq/L), Potassium 3.5-5.2 (mEq/L), Chloride 95-107 (mEq/L), Magnesium 1.6-2.4 (mEq/L), Phosphate 2.5-4.5 (mg/dL), Calcium 8.8-10.3 (mg/dL), Ionized Calcium 2.24-2.46 (mEq/L).

  • Coagulation panel: PT 10-14 seconds, PTT 32-45 seconds.

  • Imaging: No specific imaging is needed for this procedure, except for a postoperative CXR if a supraclavicular nerve block is used to rule out pneumothorax in patients with symptoms.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

With arthroscopic shoulder procedures, there are basically two main options for providing adequate anesthetic coverage. General and regional anesthesias both have relative indications and contraindications. It is up to the anesthesiologist to decide which approach is best suited to the patient and procedure.

Regional anesthesia

Peripheral nerve and plexus blocks are the preferred type of regional anesthesia for arthroscopic shoulder procedures. As the vast majority of shoulder arthroscopies are now being done on an outpatient basis, regional anesthesia for these procedures has gained popularity because it has been shown to allow patients to recover more quickly, with fewer side effects and less postoperative pain, especially when catheters and infusion pumps are used to provide extended analgesia (PUBMED:12651666, PUBMED:18299092, PUBMED:7727331, PUBMED:15851888, PUBMED:15271745).

The extended analgesia allows patients to start rehabilitation almost immediately, which is a vital part of recovery from arthroscopic shoulder surgery. From an economic point of view, regional anesthesia has been shown to be more cost effective (PUBMED:19586958). There are a variety of peripheral nerve and plexus blocks that can be used to anesthetize the shoulder. Each has its own benefits and drawbacks.

Interscalene nerve block

One of the most widely used nerve blocks for shoulder surgery.

Benefits: Provides complete intra- and postoperative analgesic coverage of the entire shoulder. Can easily be used as a single shot or continuous infusion. There are several approaches/techniques that can be used with this block: Classic technique (Winnie), Posterior approach (Pippa), and two modified lateral techniques (Meier and Borgeat).

Issues: Contraindicated in patients with severe pulmonary insufficiency or contralateral phrenic or recurrent laryngeal nerve paralysis. Also associated with a high incidence of transient Horner’s syndrome, as well as phrenic and recurrent laryngeal nerve paralysis. Rare cases of dural puncture have been reported in association with interscalene nerve blocks.

Cervical paravertebral block

A newer technique for blockade of the brachial plexus is now being used as an alternative to interscalene nerve block for shoulder surgery.

Benefits:Similar surgical success rates and postoperative pain scores as compared to interscalene nerve block. Decreased block performance time (6.2 vs. 8.4 minutes) and decreased incidence of side effects: symptomatic diaphragmatic paralysis (5% vs. 15% of patients), recurrent laryngeal nerve paralysis (5 % vs. 21% of patients), and Horner’s syndrome (16% vs. 50% of patients) compared with interscalene nerve block (PUBMED:16786913). Can easily be used as a single shot or continuous infusion.

Issues: Although this block produces less symptomatic diaphragmatic paralysis in healthy patients, it should not be used in patients with severe pulmonary insufficiency or contralateral phrenic or recurrent laryngeal nerve paralysis. Spread of local anesthetic to the epidural and subarachnoid spaces has produced transient numbness in the contralateral hand in 4% of reported cases (PUBMED:14556130). Patients also report pain at the catheter site in approximately 22% of cases.

Supraclavicular nerve block

Owing to its distance from the cervical nerve roots, supraclavicular nerve block was originally thought to be unsuitable for surgical anesthesia of the shoulder, unless combined with a superficial cervical plexus block to cover cutaneous innervation. Radiologic studies have confirmed the cephalad spread of local anesthetic between the anterior and medial scalene muscles, causing it to function similarly to an interscalene block (PUBMED:19901774).

Benefits: Similar success rates for anesthesia of the shoulder during shoulder arthroscopy compared with interscalene block (PUBMED:20686013). Better visualization of the brachial plexus in the supraclavicular fossa. Lower incidence of hoarseness compared with interscalene block.

Issues: Risk of pneumothorax due to proximity of pleural dome, although several recent studies have reported a 0% incidence of pneumothorax after supraclavicular block (PUBMED:20686013, PUBMED:19282715). Most studies report a similar incidence of hemidiaphragmatic paresis compared with interscalene block. One study reported no hemidiaphragmatic paresis in 30 patients using 20mL of 0.75% ropivacaine under ultrasound guidance, compared with an incidence of 50% using nerve stimulator (PUBMED:19916254).

Combined suprascapular and axillary nerve blocks

New technique for regional anesthetic coverage during shoulder arthroscopy. Hypothesized benefit of reduced respiratory complications.

Benefits: Satisfactory intraoperative analgesia without the use of opiates or general surgery (PUBMED:18514113). Potential to reduce respiratory complications such as pneumothorax and phrenic and recurrent laryngeal nerve paralysis, thus allowing it to be used in patients with severe respiratory dysfunction.

Issues: Limited number of procedures that can be safely carried out with this type of anesthesia, which include: repair of supraspinatus muscle tendon lesions, excisions of intratendinous calcifications of the supraspinatus muscle, acromioplasties, bursectomies, bicepital tenotomies, and humeral head surgery. There is only one small study with 20 patients to validate this evidence, with no comparison to other peripheral nerve blocks and no analysis of respiratory function.

Combined Infraclavicular Plexus and Suprascapular Nerve Block

Another option to consider in patients with respiratory failure needing shoulder surgery.

Benefits: A case report shows success of this type of combined block in a patient with acute bronchospasm for humeral head surgery. It was reported to provide complete shoulder blockade (PUBMED:12606927).

Issues:Small sample size of only one case report. Possibility of pneumothorax. Need for comparison of effectiveness with other nerve blocks.

Patient positioning related to regional anesthesia

Benefits: Both general and regional anesthesia are tolerated in this position. It is usually possible to place a laryngeal mask airway if there is a need to convert from regional to general anesthesia. It is easier for the surgeon to convert to an open procedure from this position.

Issues: There is considerable concern about cerebral perfusion in this position, particularly during general anesthesia.The surgeon often requests that the blood pressure be lowered to limit “bone bleeding” and to improve visualization. This lowering of blood pressure, in combination with the elevated position of the head, makes the possibility of cerebral ischemia quite real, and there are case reports of devastating neurological outcome.

Beach chair position:Anesthesiologists should carefully consider what mean blood pressure will be tolerable and maintain it during the procedure. Monitoring of cerebral perfusion by transcranial Doppler or cerebral oximetry has been described and may have a role. Moreover, it is important to appreciate that blood pressure recorded in the arm with the patient in the beach chair position may dramatically overestimate the pressure in cerebral vessels, and a mathematical correction of 2 mmHg for every inch of vertical displacement should be applied.

In addition, reports show that between 21-28% of patients undergoing shoulder arthroscopy in the beach chair position under interscalene block experience episodes of sudden hypotension and/or bradycardia (PUBMED:9842820, PUBMED:7762845). These episodes are thought to be caused by an activation of the Bezold-Jarish reflex (BJR). In the beach chair position, the blood pools in the lower extremities, decreasing venous return, preload, and ultimately ventricular filling. Exogenous epinephrine, either from the arthroscopic irrigation solution or mixture with local anesthetics, is thought to exacerbate the situation by increasing ventricular contractility, thus activating the BJR.

Patients receiving metoprolol were found to have a significantly lower incidence of hypotension/bradycardia. It is this author’s opinion that episodes of hypotension/bradycardia could happen just as easily with other nerve blocks, and is most likely not due to interscalene nerve block, but to patient positioning and epinephrine use.

Seung et al. proposed a mechanism for ventricular tachycardia and arrhythmias in arthroscopic shoulder procedures secondary to epinephrine flow patterns in the arthroscopic irrigation solution (PUBMED:19184069). They demonstrated that epinephrine injection into a 1-L bag of irrigation solution, if not shaken and properly mixed, has the potential to deliver a concentrated bolus of epinephrine to the patient.

Lateral decubitus position

Benefits: There is less chance of cerebral hypoperfusion and little or no risk of hypotension and/or bradycardia related to the BJR.

Issues: Traction injuries in this position have been shown to damage peripheral nerves and the brachial plexus, with incidences of paresthesias and palsies as high as 30% (PUBMED:3233114). Compression injuries to the peroneal and digital nerves and soft tissue injuries at the site of traction have also been reported.

General anesthesia

Any shoulder arthroscopic procedure can be performed with general anesthesia.

Benefits: General anesthesia provides a completely controlled environment of analgesia, muscle relaxation, and hypnosis for the patient. It provides an effective and safe option for the patient who is extremely anxious, claustrophobic, has a fear of needles, or simply refuses regional anesthesia. If the patient is allergic to local anesthetics or has an infection at the site where regional anesthesia would be administered, general anesthesia is a valuable option.

Although controversial, patients with coagulation disorders or who are taking antithrombotic medication should be considered candidates for general anesthesia. General anesthesia is always a possible backup plan in the setting of a failed block.

Issues: General anesthesia has been shown to have more side effects, with slower recovery and less postoperative pain control when compared with regional anesthesia. Although it can be used in patients with end-stage pulmonary disease, there is a risk that a pulmonary cripple may require prolonged postoperative ventilation. In patients with documented cases of malignant hyperthermia, it is probably best to use a regional technique to avoid potential triggers associated with general anesthesia.

Patient positioning related to general anesthesia
Beach chair position

Benefits-Both general and regional anesthesia are tolerated in this position. It is easier for the surgeon to convert to an open procedure from this position.

Issues- Potentially detrimental and catastrophic outcomes have been reported in relation to shoulder surgery under general anesthesia in the beach chair position. These include ischemic brain and spinal cord damage, visual loss, and ophthalmoplegia (MID:16171668, PUBMED:12598282) The beach chair position predisposes patients to reductions in cerebral profusion pressure.

During general anesthesia, autoregulation of the cerebral perfusion pressure is reduced. The risk is further increased by the use of deliberate hypotension and inaccurate blood pressure monitoring, such as placing the blood pressure cuff around the calf. It is recommended to avoid deliberate hypotension, maintain accurate blood pressure values, and promptly treat any unexpected hypotension (PUBMED:20810089, PUBMED:19412145).

Lateral decubitus position

Benefits- Little or no risk of ischemic events due to decreased cerebral perfusion pressure.

Issues- Traction injuries in this position have been shown to damage peripheral nerves and the brachial plexus, with incidences of paresthesias and palsies as high as 30% (PUBMED:3233114). Compression injuries to the peroneal and digital nerves as well as soft tissue injuries at the site of traction have also been reported.

Monitored anesthesia care

Most shoulder arthroscopic procedures are too painful to be done under monitored anesthesia care without the use of regional or general anesthesia.

6. What is the author's preferred method of anesthesia technique and why?

The author strongly believes that regional techniques are beneficial for most people. In most patients, the possible neurological consequences of a regional technique are mentioned with an opportunity provided for questions. In patients whose livelihood requires fine motor skill of the arm (professional musicians, professional athletes, etc.), a more detailed discussion of risk vs. benefit is undertaken. The most conservative approach in these patients would be a general anesthetic, but the author believes patients should have the option of selecting a regional technique.

Ultrasound vs. neurostimulation

The author is convinced that ultrasound is a superior technique because it is faster to perform and is at least as reliable as neurostimuation techniques.

The added benefit of watching the plexus being surrounded by local anesthetic cannot be overemphasized.

Agent used

The author finds either 0.5% bupivacaine or 0.5% ropivacaine to be acceptable agents. Occasionally, 0.75% ropivacaine will be administered, but, in the author’s experience, it is usually unnecessary. When working a situation where the block needs to work quickly, the author will substitute some of the volume with 2% lidocaine; this will speed the onset of the block but will diminish the duration.

The author does not add bicarbonate or epinephrine because, in his experience, it is more trouble than it is worth. However, the author will often add 4-10 mg dexamethasone, as it seems to prolong a quality block. Other adjuvants, such as clonidine and ketorolac, are not part of the author’s practice.

What prophylactic antibiotics should be administered?

Utilize current Surgical Care Improvement Project (SCIP) recommendations. Most patients will receive a dose of a cephalosporin, such as cefazolin, within an hour prior to surgical incision.

What do I need to know about the surgical technique to optimize my anesthetic care?

It is helpful to know what procedure is planned and where the surgeon plans to place the portals. With nerve blocks, it is important to ask the surgeon to supplement the cutaneous aspect of the block, especially in the posterior area of the shoulder.

What can I do intraoperatively to assist the surgeon and optimize patient care?

The major issue with this procedure is blood pressure management. As there is often a component of periosteal shaving and drilling into bone, the surgeon may encounter difficulty with bleeding and visualization. You may be asked to lower the blood pressure. This should be carefully considered, especially in the beach chair position. It is often possible for the perfusion pressure of the arthroscopic fluid to be increased, but this will contribute to increased local tissue edema.

What are the most common intraoperative complications and how can they be avoided/treated?

  • Hypotension/inadequate cerebral perfusion: this should be avoided with careful blood pressure measurement and pressor administration

  • Bezold-Jarish reflex (BJR): maintain venous return through leg elevation

  • Local anesthesia toxicity: careful aspiration, use divided doses, and have 20% Intralipid immediately available for rescue.

Cardiac complications

There are no cardiac complications specifically associated with this procedure.

Pulmonary

Although phrenic nerve paresis is very common following regional anesthesia of the shoulder, it is very unlikely to produce notable respiratory compromise. This happens only in the most fragile of patients. For most patients, it is an annoyance. It is very helpful to warn patients preoperatively, especially the asthmatic patient, as the sensation of phrenic paresis apparently feels very similar to an asthma attack. Those who have received a supraclavicular block, or any needle near the dome of the lungs, should be advised about the possibility of pneumothorax, with instructions to seek medical care if breathing difficulties arise.

Neurologic

When carefully looked for, there is a fairly high incidence of transient neurologic symptoms following regional anesthesia of the upper extremity. These are usually sensory (dysesthenia etc.) and of short duration. Patients should be advised of this preoperatively and reassured that these will essentially all resolve over time.

Motor issues that remain following the expected duration of the block should be addressed. These patients should be seen and examined and the extent of the issue should be documented. Because these can often be due to positioning, intraoperative traction, or a preexisting condition such as carpal tunnel syndrome, the anesthesiologist should not automatically assume “ownership” of the issue, but should be actively involved with appropriate referral to a neurologist for consideration of nerve conduction studies, etc.

a. Neurologic:

Unique to procedure: As above, neurologic issues following surgery, especially following regional anesthesia, should be addressed. Often this involves a discussion over the phone, but if there is a motor issue, it has been the author’s practice to see and examine the patient and to be in active communication with the surgeon and a consulting neurologist. Neuropraxias from regional anesthesia almost always resolve over time. However, the symptoms may be from some other etiology, such as carpal tunnel or carpal ulnaris syndrome, so other causes should be pursued.

b. If the patient is intubated, are there any special criteria for extubation?

There are no unusual extubation criteria for patients who have received a general anesthetic.

c. Postoperative management

What analgesic modalities can I implement?

For those who have received general anesthesia, a multimodal approach is usually effective. This involves the administration of NSAIDs, acetaminophen, and opioids. Some centers use preoperative pain protocols that involve administration of these medications preoperatively and often include the addition of pregabalin.

There is evidence-based information to support the administration of small amounts of intraoperative ketamine (0.1 to 0.3 mg/kg) to help with postoperative analgesia.

Our center also offers postoperative “rescue” blocks to those patients who had originally chosen a general anesthetic, but who are in excessive pain postoperatively or are not tolerating postoperative pain medications. The patient who has received a single-shot regional technique needs to be instructed about the experience of block resolution. It is advisable for the patient to have taken an NSAID and some form of opioid before the expected resolution of the block. The author instructs patients to begin these medications when the first indication of discomfort arises.

What level bed acuity is appropriate?

Most of these procedures are done on an outpatient basis. Obviously, any medical complication may lead to hospitalization, as may the occasional situation of a patient with intractable pain or nausea and vomiting. In the author’s experience, it is very rare for the regional anesthetic patient to return for inadequate postoperative pain control, but this does occur occasionally.

What are common postoperative complications, and ways to prevent and treat them?

The most common issues are pain, which should be anticipated and treated with appropriate multimodal therapies; nausea, which can be addressed by providing patients with a prescription for antiemetic medications that can be filled if necessary; and neuropraxia, which should be addressed as above.

What's the Evidence?

Eagle, KA, Berger, PB, Calkin, BR, Chaitman, BR, Ewy, GA, Fleischman, KE. “ACC/AHA Guideline Update for Perioperative Cardiovascular Evaluation for Noncardiac Surgery–Executive Summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery)”. Anesth Analg. vol. 94. 2002 May. pp. 1052-64. (Guidelines and flowchart on perioperative cardiac evaluation.)

Horlocker, TT, Wedel, DJ, Benzon, H, Brown, DL, Enneking, FK, Helt, JA. “Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation)”. Reg Anes Pain Med. vol. 28. 2003 May-Jun. pp. 172-97. (Good discussion and guidelines on the risks associated with anticoagulated patients.)

Checcucci, C, Allegra, A, Bigazzi, P, Giansesello, L, Ceruso, M, Gritti, G. “A new technique for regional anesthesia for arthroscopic shoulder surgery based on a suprascapular nerve block and an axillary nerve block: an evaluation of the first results”. Arthroscopy. vol. 24. 2008 Jun. pp. 689-96. (Explains a new technique for shoulder arthroscopy using regional anesthesia without hemidiaphragmatic paresis.)

Martinez, J, Sala-Blanch, X, Ramos, I, Gomar, C. “Combined infraclavicular plexus block with suprascapular nerve block for humeral head surgery in a patient with respiratory failure: an alternative approach”. Anesthesiology. vol. 98. 2003 Mar. pp. 784-5. (Explains a new technique for shoulder arthroscopy using regional anesthesia without hemidiphragmatic paresis.)

Liu, SS, Gordon, MA, Shaw, PM, Wilfred, S, Shetty, T, Yadeau, JT. “A prospective clinical registry of ultrasound-guided regional anesthesia for ambulatory shoulder surgery”. Anesth Analg. vol. 111. 2010 Sep. pp. 617-23. (Shows that supraclavicular nerve blocks can be just as effective as interscalene blocks for shoulder arthroscopy.)

Renes, SH, Spoormans, HH, Gielen, MJ, Rettig, HC, van Geffen, GJ. “Hemidiaphragmatic paresis can be avoided in ultrasound-guided supraclavicular brachial plexus block”. Reg Anesth Pain Med. vol. 34. 2009 Nov-Dec. pp. 595-9. (Shows that it is possible to avoid hemidiaphragmatic paresis with the proper use of ultrasound guidance in supraclavicular brachial plexus blocks.)

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