Open reduction of humeral fracture

What the Anesthesiologist Should Know before the Operative Procedure

Humeral fractures occur in all age groups from pediatric to the elderly. They can be treated in a variety of ways depending on the nature and location of the fracture. They can be classified into three groups.

Upper end including the humeral neck near the shoulder joint. This fracture can involve the head of the humerus and disruption of the rotator cuff tendons. Surgical neck fractures are the most common. Age groups can be any but often most often seen in the elderly from a fall or in the younger population from trauma. The axillary nerve can be injured with a fracture in this location.

Mid-shaft fractures can injure the radial nerve as it lies in the mid-shaft radial groove.

Lower end, in the supracondylar area. Involves the lower humerus and elbow joint area, the most common site in children, or older women with osteoporosis. Etiology is usually from a fall on an outstretched hand. The ulnar nerve can be involved in the medial condyle area; the median and radial are associated with a fracture in the supracondylar area.

Treatment options depend on the severity and displacement of the fracture, include reduction and cast placement, reduction and percutaneous pinning, open reduction and internal fixation.

1. What is the urgency of the surgery?

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

Emergent- Supracondylar fractures are very common emergent procedures secondary to associated vascular compromise, possible positional displacement that could cause a nerve injury if left untreated (most commonly the ulnar or radial nerve, but any nerve can be involved); if not reduced, impending compartment syndrome.
Urgent- Any of the above in lesser degree or an open fracture. An open fracture should be repaired within 6-8 hours.
Elective- Surgery can be elective if the patient needs to be stabilized for other injuries, swelling needs to be decreased, or the patient has other injuries that necessitate treatment first.

2. Preoperative evaluation

Usually most children are otherwise healthy. In any trauma-associated injuries such as head injuries, abdominal trauma or other fractures, they must be evaluated with appropriate triage. In the elderly, the origin of the fall should be elucidated including dizziness, TIA, stroke, MI, seizures, diabetes.

Time and content of food and beverages should be documented.

Medically unstable conditions warranting further evaluation include: Myocardial infarction and active ischemia, unstable arrhythmias, evolving stroke, seizures, unstable diabetes, untreated hypertension.
Delaying surgery may be indicated if: the patient shows any signs of instability such as continued fall in hematocrit from trauma, full stomach; NPO guideline in the elective case only. Cardiac clearance and testing may be unnecessary for a peripheral procedure with a small amount of blood loss.

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

Perioperative evaluation- Should contain all systems and physical exam. The neurologic exam, sensory and motor nerves of the extremities and vascular integrity should be documented. Often a diagram is helpful.
Perioperative risk reduction strategies- Routine cardiac clearance is often not necessary. But if the patient fits into the elective category, patients with minor abnormalities per the American Heart Association/American College of Cardiology (AHA/ACC) may proceed with surgery. The amount of blood loss is small. The beginning tolerated Hgb should be adjusted to the patient’s need for oxygen-carrying capacity in regard to their cardiovascular system impairment.

b. Cardiovascular system

Acute/unstable conditions: Acute/unstable conditions should be investigated for possible cause of injury, arrhythmia or MI, TIA or stroke. Testing includes laboratory testing for troponin, EKG, transthoracic echo, possible cardiac consultation. Obtain a good clinical history of the patient’s functional status and any prior cardiac evaluations.
Rheumatoid patients can have chronic pericardial effusions, valvular disease and cardiac conduction defects.

Baseline coronary artery disease or cardiac dysfunction – Goals of management: – risk reduction strategies:

Monitoring- Full intraoperative monitoring. Invasive only if warranted by patient’s CV status.
Goals- optimize myocardial oxygen supply and demand ratio.

c. Pulmonary

COPD :be cautious of the effect of regional block on the diaphragm. Shortness of air can be a reason for admission for observation or supplemental oxygen. Rare complication of pneumothorax in this group can be serious in this group of patients; consider a different site of block such as infraclavicular rather than interscalene or supraclavicular.
OSA, Sleep Apnea : This subset of patients can benefit substantially from a regional anesthesic and analgesia of this type by decreasing the pain and the resultant sparing of the use of opioids; the risk of over-sedation from post-op analgesics is decreased.
Perioperative evaluation- clinical history of smoking, shortness of air, exacerbations, home oxygen, exercise tolerance
Perioperative risk reduction strategies- continue current medications, may need preoperative nebulizer treatment or possibly additional steroids. The choice of regional depends on the dependency of the diaphragm for breathing. That needs to be evaluated carefully based on functional capacity, arterial blood gas results, chest x-ray, medications and past history.
Reactive airway disease -assess severity of disease, triggers, frequency of attacks, medication history, ER visits, hospitalizations.
Rheumatoid patients may have pulmonary fibrosis, pulmonary effusion.
Perioperative risk reduction strategies: Continue medications, possible nebulizer treatment pre- or intra-operatively. Inhalational vs intravenous general anesthesia, maintaining full muscle relaxation. Regional may be important component for intraoperative and postoperative management to avoid bronchospasm.

d. Renal-GI:

i. Perioperative evaluation- assess renal function for chronic renal insufficiency, volume status- history of oral intake, vital signs, urine output. if indicated- laboratory testing of BUN, creatinine, sodium, hemoglobin.

ii. Perioperative risk reduction strategies- avoid NSAIDs, aminoglycosides in chronic renal insufficiency

Gastrointestinal- evaluate for full stomach, last intake and content. Delayed emptying occurs with trauma and conditions of stress.

ii,. Perioperative risk reduction strategies- H2 blocker, oral antacid, rapid sequence induction, regional anesthesia in the face of a difficult airway must be evaluated. Oral NG tube after induction to decompress stomach.

e. Neurologic:

Acute issues: Evaluate for possible etiology of injury- seizures, TIA, stroke,
Detailed history of the injury if possible, loss of consciousness, neurologic deficits- central and peripheral in regards to the injury, sensory and motor with a diagram.
Chronic disease:- History of carotid disease, seizures, medication history. Rheumatoid arthritis and osteoarthritis common in the adult population, Examine cervical spine and jaw for adequate movement. Hoarseness can indicate cricoarytenoid joint involvement with possible difficulty intubation.
Risk reduction strategy- maintain baseline blood pressure if carotid disease is present with intermittent vasopressors or continuous infusion, cerebral function monitor.

f. Endocrine:

Evaluate for diabetes

Perioperative- obtain history, medications, test for preoperative glucose level

Risk reduction strategies- maintain glucose at normal level; avoid hypoglycemia or hyperglycemia. Tight control is controversial and not recommended at this time.

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) Hematologic: If increased INR or decreased platelets, a superclavicular is indicated rather than the deeper infraclavicular. ASRA guidelines state to consider the depth of the block vs the risks and benefits.

Examination of the peripheral nervous system including dermatome deficits, sensory deficits and motor deficits. Examine radial and ulnar pulses both at the wrist and elbow.

Helpful to include a diagram of any deficits that are found.

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

All medications should be documented including herbals, vitamins, and relevant OTC drugs. All medications can be continued except as noted below.

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

Most patients will already be on pain medication when they arrive in the operating room.

The additive effect of additional pain medication should be considered to avoid undue respiratory depression.

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

All prescription medications can be continued except as mentioned above. Herbals should be discontinued.

Cardiac – ACE inhibitors are best held to avoid intraoperative hypotension.

If beta blockers are not routinely taken, there is currently no indication to routinely institute them preoperatively or intraoperatively unless the patient’s condition warrants.
Pulmonary
Renal
Neurologic
Anti-platelet -any anti-platelet medication including clopidogrel should be discontinued, unless indicated for a coronary stent. ASA is usually not a contraindication for surgery or for a regional block. A superficial block is not contraindicated in the situation of hemostatic prophylaxis. ASRA guidelines state to consider the depth of the block vs the risks and benefits
Psychiatric

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

The allergy should be documented for type and extent of reaction. Prior operative record is helpful to obtain.

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.

Notify the Operating Room personnel to avoid latex products and multiuse vials.

l. Does the patient have any antibiotic allergies-

Antibiotic sensitivity must be based on type of allergy. The past oral history of antibiotic treatment is helpful.

If PCN allergy is positive, the reaction should be characterized before a non-cefazolin family is substituted. Most PCN allergies will be nonresponsive to a cephalosporin. A test dose is recommended if a history of a mild reaction is given. Caution and careful observation is warranted. Otherwise, vancomycin, clindamycin or alternative antibiotic is indicated.

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:

Insure MH cart available:

[- MH protocol]

Family history or risk factors for MH:
Local anesthetics/ muscle relaxants: It is very rare to have a true allergy to local anesthetics. Most are a reaction to injected epinephrine-containing solutions or methylparaben in solution. Allergic reactions to esters have been reported. No cross reactivity to amides so amides can be used. Difficult to obtain a skin test if time is available to do one. Best to obtain careful history and avoid if positive. More common is for a patient to say local anesthetics do not work on me which has been reported. Can switch the class from amide to ester or vice versa if history is well documented. Must temper risk vs benefit in all cases.

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

Hemoglobin- evaluate in light of volume status so a hematocrit is helpful as well.

Electrolytes- if on potassium-wasting diuretics or patient history indicated.

INR PT/PTT platelets- indicated if abnormality is suspected, regional block, or extensive resuscitation.

EKG- age and comorbidity indications

Hemoglobin levels: Normal levels for age. If low, evaluation should be based on the need for oxygen-carrying capacity of the individual in light of their comorbidities.
Electrolytes: within normal limits. Adjust medications if renal insufficiency is shown. Use esters local anesthetics instead of amides.
Coagulation panel: within normal limits

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

The humeral fracture has a broad scope of treatment regimens. The simple fracture may require only sedation for a percutaneous pin. The fracture may initially be treated with an external fixator or progress to an open plating and screws. The humerus fracture presents the most possibilities for different positions. These positions present their own various challenges. Possibilities include supine, beach chair, lateral, or prone. The surgeon should discuss the desired position along with the anticipated reduction technique. All but the simple pin are amenable to a regional block for pain control in conjunction with general anesthesia or a regional block for the surgery itself with sedation.

a. Regional anesthesia -Is often indicated for pain control post fracture treatment. Regional anesthesia can be the sole anesthetic or an avenue for intraoperative and postoperative pain control. Often the anesthetic of choice in the elderly patient to reduce the risks with general anesthesia with co-morbidities and also general anesthesia in the presence of a full stomach. Supplemental sedation with a small amount of propofol augments a total regional anesthetic technique.

A single shot block may be indicated or a continuous catheter may be more appropriate and would first depend on the extent and duration of anticipated pain post operatively. Secondly the indication for placement of a continuous catheter must take into consideration the patient qualifications and the physician’s ability to care for the postoperative patient in hospital and/or on an outpatient basis.

Neuraxial-not indicated for humeral fracture
Peripheral Nerve Block

Benefits- and upper extremity block can be approached in several locations along the brachial plexus for a humeral fracture. An interscalene, supraclavicular, vertical infraclavicular block or infraclavicular block may cover the nerve supply to the affected area of the upper arm. Can be performed in patients who are on antiplatelet therapy. Risks of vessel puncture where compression is not possible may favor other more superficial sites such as interscalene or supraclavicular approaches. Do not need to hold antiplatelet prophylactic therapy for catheter removal. Catheter placement will provide for early physical therapy which is very important and especially in distal fractures involving the elbow to allow for early mobilization with minimal pain, incidence of hoarseness, Horners syndrome

Interscalene- is well suited for any of the fractures but especially the proximal to mid-shaft fractures. The inferior trunk, which includes the ulnar distribution, can occasionally be missed and should be considered in the fracture location but should not be a factor for a humeral fracture. Can be approached from the anterior or posterior side of the neck. The anterior is the most common. Can be done with ultrasound or nerve stimulator. Ultrasound provides a measure of exactness of the endpoint of the needle which, although not proven, may add additional safety.

The interscalene block does not provide anesthesia for the entire posterior capsule. The suprascapular nerve may need to additionally be blocked; this can often be done in the operating room by the surgeon.

Drawbacks-the phrenic nerve has to be thought of as possibly or reliably being blocked which can affect diaphragmatic function. This should enter into the decision of performing this approach on a patient dependent on diaphragmatic function. Rarely, even in the non-COPD patient, a small amount of air hunger may necessitate additional observation or even admission. Other complications include: intravascular injection with seizures or cardiac depression, total spinal, epidural, laryngeal block causing hoarseness, pneumothorax, stellate ganglion block with Horners syndrome. Another drawback is that the superficial location of this block makes it difficult but not impossible to maintain a catheter in place for an extended length of time. A catheter in this location will often leak at the skin level and need reinforced dressings. Another site of blockade such as supraclavicular or vertical infraclavicular block can be chosen.

Issues- must respect the surrounding structures such as the spinal cord, vertebral artery and carotid vessels. Compressibility of blood vessels not optimal.

Supraclavicular block-provides anesthesia to the upper and lower arm. A high incidence of pneumothorax is reported with a non-ultrasound guided approach in inexperienced hands. Low incidence of pneumothorax in ultrasound approach, much lower incidence of phrenic nerve paralysis, provides complete anesthesia of the lower arm if the C8 root is targeted (corner pocket).

Vertical infraclavicular blocks -site is the midpoint of the clavicle. Most often performed with nerve stimulator but can be done with ultrasound as well.

Drawback- cannot provide compression if vessel puncture occurs.

Issues. If needle is too medial or too deep (greater than 4 cm) chance of pneumothorax occurs.

Infraclavicular coracoid approach- occurs outside of the thorax as the brachial plexus crosses underneath the coracoid process to enter the axillary area

Can be done with ultrasound or nerve stimulator approach.

Drawback- the deepest site of blockade of the upper extremity. Usually cannot discern the nerves themselves but their relation to the axillary artery is a reliable landmark. Requires the most local to ascertain spread to the medial cord of the brachial plexus. Cannot compress if vessel puncture. Intravascular injection possible.

Axillary approach- usually not indicated for humeral fracture. Only if the fracture was in the most distal humerus and pain does not limit ability to position patient for the block.
Dose of local anesthetics- varies by operator. Reports exist for 10-40 cc or more. Some studies report that lesser doses are desirable to minimize possible phrenic nerve paralysis.

The upper limit of amount of local anesthetic does not follow currently published tables due to the decrease in uptake in the periphery. It is commonplace to perform multiple blocks at the same time and exceed the published amounts without having signs of toxicity.
Choice of local anesthetics

The main principle is to match the concentration and choice for the desired effect.

An anesthetic dose vs an analgesic dose is a matter of concentration.

For example- Ropivacaine 0.5% or higher is anesthetic, 0.2 or less is analgesic

Ropivicaine, Bupivacaine provide a 10-12 hour block

Mepivacaine, Lidocaine provide a 1-2 hour block

Mepivacaine and Lidocaine may be given in conjunction with a longer acting block to speed the onset. Although this is not proven, it is commonly practiced.

Adjuncts are up to the provider. Some examples are: epinephrine to act as a vascular marker and to delay uptake to prolong the action. It has been shown to increase the extent of nerve injury if injected intraneurally in the fascicles of the nerve. Butorphanol and dexamethasone have been shown to increase analgesia after dissipation of the original block. Clonidine has mixed studies but often does not outlast the original block. Sedation is a common side effect. Bicarbonate to increase speed of onset by several minutes. Precipitates easily with ropivacaine and bupivacaine

Match the duration for the desired duration of the block. Bear in mind that for single shot blocks, longer is not always better. Discuss with the patient, taking into consideration the probable postoperative pain intensity. Most patients would rather have an analgesic block post surgery rather than an anesthetic arm.

Toxicity of local anesthetics- central nervous excitation with seizures followed by depression in higher doses, cardiovascular depression, possible irreversible cardiac channel bonding with bupivacaine. Treatment consists of prevention first with sequential incremental aspiration during injection, rapid recognition and treatment consisting of ACLS implementation, maintenance of the airway to avoid an increase in carbon dioxide, supplemental oxygen. Seizures can be suppressed with propofol but this may exacerbate cardiac depression if cardiotoxicity is present; therefore, dose with appropriate caution. Early use of 20% Intralipid for intravascular injection is now becoming more commonplace and the only true treatment for toxicity. Intralipid should be readily available wherever regional blocks are utilized.

b. General Anesthesia- Is often chosen as the primary anesthetic with or without regional anesthesia to ascertain a secure airway because this surgery often occurs in positions other than supine positions. Patients are often trauma victims and have other associated injuries and will better tolerate the positions required for surgery under general anesthesia.

Benefits- controlled, secure airway in situations including multiple injuries, prone, lateral or beach chair positions.
Drawbacks- positioning and proper padding of vulnerable areas in the lateral, prone and beach chair positions. Blood pressure maintenance and a remote possibility of air embolism in the beach chair position.
Other issues- usually blood transfusion is not necessary; possibility to overdose anesthetic when analgesia if covered with a regional block. Cognitive function monitoring recommended.
Airway concerns- Usual airway precautions. With multiple trauma victims, caution with positive pressure ventilation if rib fractures are present. Consider the need for a prophylactic chest tube.

c. Monitored Anesthesia Care –

Usually only indicated for percutaneous pinning, which is more common in the pediatric population. Most, due to age, will need general anesthesia.

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

Utmost is communication with the surgeon after the preoperative evaluation of the patient to determine readiness for surgery. Unless there is a dislocation, open fracture, nerve or vascular compromise, humeral fracture treatment can allow for optimization of the patient. Other necessary critical information is how the fracture is to be treated and the desired position of the patient. If the patient’s co-morbidities preclude a desired position, such as a beach chair, I will discuss the risks with the surgeon.

After a careful documentation of the neurovascular status of the patient, I will explore the possibilities of a regional block and possible catheter placement. Preexisting nerve damage does not preclude a block but should be documented. The humeral fracture has a significant incidence of neurologic injury.

The block will optimally be placed preoperatively but can be placed postoperatively as well with consent obtained preoperatively. If the patient and position are amenable, it may be the operative anesthetic technique. This will need to be decided on a case by case basis. If a combined technique is indicated, I prefer to maintain hypnosis with an inhalational or total intravenous anesthetic with a regional block. Multimodal technique with small doses of ketamine, intravenous acetaminophen and gabapentin or pregabalin are used to complement pain modulation.

The goal is to obtain an analgesic block and not an anesthetic block in this case, so a lesser concentration (0.2% ropivacaine) will be used. I will use consciousness monitoring intraoperatively to optimize hypnotic level and use narcotics only to blunt the response to intubation or for associated injuries. I will use fluids and pharmacology to manage blood pressure fluctuations. If a catheter is placed, I plan to leave it in for 2-3 days. If the patient is discharged, a disposable pump is given to the eligible patients. This does not preclude SVT prophylaxis during the postoperative course.

What antibiotics should be administered?

Cefazolin, Cefuroxime, or Vancomycin or Clindamycin if B-lactam allergy

Proximal Humerus Fractures: are the third most common fracture after hip fractures and distal radius fractures. A great majority can be treated non-operatively. Operative treatment can include an intramedullary nail, internal fixation, or in some cases hemiarthroplasty. Surgical management of proximal humerus fractures include closed reduction with no fixation, percutaneous fixation, open reduction with internal fixation, and humeral head replacement including hemiarthroplasty.

Midshaft Humerus Fractures: Treatment

Most closed fractures of the humeral shaft can be treated successfully with closed methods. Surgical therapy operative techniques include surgical fixation using plates and screws, intramedullary (IM) fixation or external fixation of humeral shaft fractures often for open fractures.

The patient’s position for surgery is determined by the method chosen for fixation. Antegrade nailing of the humerus is performed with the arm draped free and the patient in either a beach chair or a supine position. Retrograde nailing is performed with the patient in the prone position. Positioning for placement of plates and screws is determined by the approach chosen. During a posterior approach, the patient is positioned prone. The patient is positioned supine for an anterior approach. External fixation is performed with the patient supine.

Distal Humerus Fractures

Distal humerus fractures are uncommon injuries in adults. These fractures occur near the elbow joint and are much more common in children. They are usually treated with percutaneous pin placement under general anesthesia. Nerve injuries can occur with pin placement to the ulnar nerve and the radial nerve. In adults they are more commonly treated by internal fixation or possibly elbow hemiarthroplasty.

Percutaneous pinning- usually in children who rarely tolerate anesthesia awake until possibly age 6 or greater.

d. What are the most common intraoperative complications and how can they be avoided?

Cardiac complications- Avoid undue stress on the heart by adequate suppression of sympathetic nervous system during intubation including adequate opioids, intravenous lidocaine at the suppression dose of 1.5 mg/kg and not that used to minimize the pain of propofol. Limit the induction dose and allow enough time for the patient’s circulation time and cardiac output for the propofol dose to reach the brain if rapid sequence induction is not indicated to avoid unnecessary hypertension, tachycardia, or hypotension on induction. Continue beta blockers if indicated or use esmolol to control tachycardia on induction.
Pulmonary- lower extremity compression devices, prophylactic chest tube if rib fractures are present, avoid an interscalene block in the diaphragm-dependent patient
Neurologic- Document pre-operative neurologic status of the extremity and provide adequate muscle relaxation to optimize reduction of the fracture with opposing musculature. Diligent detail to position and padding all pressure points, maintain tight blood pressure control especially if the beach chair position is required.
Compartment syndrome- is possible, especially with supracondylar fractures. Close neurologic monitoring is necessary

Unique to this procedure.

Surgical Position Beach Chair

In the beach chair position, anesthesia-related complications are more common than in the lateral decubitus position, including spinal and cerebral ischemia and death.

The beach chair position can cause impaired venous return from the dependent lower extremities, and, coupled with vasodilatation from anesthetic agents, can result in difficulty in maintaining the blood pressure. Careful monitoring of the blood pressure is essential to avoid extreme hypotension and cerebral hypoperfusion. Blood pressure cuffs should be placed at the level of the heart. Leg placement of the cuff should be avoided. The placement of the head and neck should receive special attention to avoid compression of blood flow both for congestion and a compression of the carotid resulting in a decrease in cerebral blood flow. When supporting the head, undue pressure on the hypoglossal nerve should be avoided. Visual loss has been reported and the possibility exists of the risk of air embolus simply from being in this position.

In a study of patients undergoing elective shoulder surgery who had similar anesthetic management, those operated on in the beach chair position while maintaining the same hemodynamic values as patients placed in the lateral decubitus position, still experienced lower regional cerebral tissue oxygen saturation or Sct0₂values intraoperatively and a higher incidence of cerebral desaturation events.

The Anesthesia Patient Safety Foundation recently introduced a position statement questioning the risks related to using the beach chair position. The global ischemic brain damage related to surgery in this position may reflect an unrecognized cerebral hypoperfusion. Murphy showed an 80% incidence of cerebral desaturation events in the beach chair group vs. 0% in the lateral decubitus group.

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

Normal criteria for extubation

c. Postoperative management

What analgesic modalities can I implement? regional block and catheter for 2-3 days in an analgesic concentration placed either pre- or post- operatively. Multimodal therapy with ketamine in the propofol or bolus intraoperatively, gabapentin or pregabalin, intravenous or oral acetaminophen preop and into the postoperative period. A PCA for the first night may be indicated, then oral narcotics as necessary. Suresh has reported on postop supraclavicular blocks for children after neurologic and compartment syndrome has been ruled out.
What level bed acuity is appropriate? Not indicative of procedure but based on patient’s condition
What are common postoperative complications, and ways to prevent and treat them? (Example: postop delirium, postop DVT/PE, reoperation for bleeding, functional decline, increased mortality)
The elderly have a high incidence of delirium and cognitive dysfunction – a regional block will help to diminish the amount of hypnotic anesthetic needed and will decrease the incidence of delerium.
DVT prophylactics – LMWH and early ambulation will be facilitated with adequate pain control
Complications of beach chair- tight control of blood pressure, cuff or align at the level of the heart, possible cerebral oximetry and conscious monitoring.

What's the Evidence?

Murphy, GS, Szokol, JW, Marymont, JH. “Cerebral oxygen desaturation events assessed by near-infrared spectroscopy during shoulder arthroscopy in the beach chair and lateral decubitus positions”. Anesth Analg. vol. 111. 2010. pp. 496-505.

Suresh, S, Sawark, JP. “Performing US-guided nerve blocks in the postanesthesia care unit (PACU) for upper extremity fractures: is this feasible in children”. Correspondence. Pediatric Anesthesia. vol. 19. pp. 1237-1252.

Martínez, J, Sala-Blanch, X, Ramos, I, Gomar, C. “Anesthesiology . Uses Infraclavicular approach in a patient with significant lung disease”. Anesthesiology. vol. 98. 2003. pp. 784-5.

Liu, SS, Gordon, MA, Shaw, PM, Wilfred, S, Shetty, T, Yadeau, JT. “Details large series of 1000 shoulder surgery with regional anesthesia and associated incidence of success and complications”. Anesth Analg. vol. 111. 2010 Sep. pp. 617-23.

Koscielniak-Nielsen, ZJ, Frederiksen, BS, Rasmussen, H, Hesselbjerg, L. “Supraclavicular more reliably blocked the axillary nerve. Both were effective for the arm. The site of surgery determines the block. Infraclavicular was preferred for lower arm surgery”. Acta Anaesthesiol Scand. vol. 53. 2009 May. pp. 620-6.

Neal, JM, Gerancher, JC, Hebl, JR. “Upper extremity regional anesthesia: essentials of our understanding, 2008”. Reg Anes Pain Med. vol. 34. 2009. pp. 134-70.

Fredrickson, MJ, Abeysekera, A, Price, DJ, Wong, AC. “Continuous interscalene ropivacaine 0.2% 2 ml; with mandatory 6 hourly (and PRN) boluses provides similar analgesia after rotator cuff repair but with reduced side-effects compared with 5 ml; with PRN only boluses”. Br J Anaesth. vol. 106. 2011 Feb. pp. 239-45.

Fredrickson, MJ, Smith, KR, Wong, AC. “Ropivacaine interscalene block requires a threshold volume and concentration, with concentration primarily determining motor block”. Anesthesiology. vol. 112. 2010 Jun. pp. 1374-81.

Clark, LD. “Infraclavicular Blockade. Regional Anesthesia”. 2005.

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