Anesthesia for Orthopedics and Podiatry Flashcards
Purpose of the Pneumatic Tourniquet
Maintains a relatively bloodless field during intraoperative blood loss
Aids in the identification of vital structures
Expedites the procedure
Components of the tourniquet
Inflatable cuff
Connective tubing
A pressure device
A timer
Safety Measures for Preventing Tourniquet Complications
Tourniquet should be applied where the nerves are best protected in the underlying musculature
Test equipment for proper functioning before use
Tourniquet should not be used for > 2 hours
Use the widest cuff possible (use lower cuff pressure to occlude the
blood flow)
A minimum of 2 layers of padding should be placed around the extremity
Tourniquet size should be half the limb diameter and the cuff should overlap 3-6 inches
Tourniquet size should allow placement of 2 fingers between the tourniquet and the cast padding
When possible, extremity should be exsanguinated prior to tourniquet inflation
Only minimally effective pressure should be used for occluding blood flow:
Upper extremity: 70-90 mm Hg > SBP
Lower extremity: 2X the SBP
The pressure display must accurately reflect the pressure in the tourniquet bladder
Use the ____ cuff possible (use ___ cuff pressure to occlude the blood flow)
widest, lower
Tourniquet size should be ____ the limb diameter and the cuff should overlap ___to___ inches
half, 3-6 inches
Only minimally effective pressure should be used for occluding blood flow:
Upper extremity: __to__ mm Hg > SBP
Lower extremity: ___ the SBP
Upper extremity: 70-90 mm Hg > SBP
Lower extremity: 2X the SBP
Physiologic Changes Caused by Limb Tourniquets: neuro
Abolition of somatosensory evoked potentials and nerve conduction occurs within 30 minutes
> 60 minutes tourniquet time causes tourniquet pain and hypertension
> 2 hours tourniquet time may result in postoperative neurapraxia
Evidence of nerve injury may occur at the skin level underlying the edge of the tourniquet
Physiologic Changes Caused by Limb Tourniquets: muscle
Cellular hypoxia develops within 2 minutes
Cellular creatinine level declines
Progressive cellular acidosis occurs
Endothelial capillary leak develops after 2 hours
Systemic Effects of Tourniquet Inflation
Elevations in arterial and pulmonary artery pressure occur (this is usually slight to moderate if only one limb is occluded)
Systemic Effects of Tourniquet Release
Transient decrease in core temperature
Transient metabolic acidosis
Transient decrease in central venous oxygen tension occurs, but systemic hypoxemia is unusual
Acid metabolites (i.e., thromboxane) are released into the central circulation
Transient fall in pulmonary and systemic arterial pressure occurs
Transient increase in end-tidal carbon dioxide occurs
Non-Pneumatic Tourniquets
A silicone ring tourniquet (SRT) may be used for brief procedures
Consists of a silicone ring wrapped in a sleeve, with 2 pull handles connected by straps
At the end of surgery, the silicone ring tourniquet is removed by cutting the silicone ring
These tourniquets are not electronic. Therefore, tourniquet time must be closely monitored.
Tourniquet Pain
Tourniquet pain occurs 45-60 minutes after tourniquet inflation
Once the pain begins, it is resistant to analgesics and anesthetic agents, regardless of anesthetic technique
Ischemic pain of associated with tourniquet application is similar to the pain of thrombotic vascular occlusion and peripheral vascular disease
What are the symptoms of tourniquet pain?
Dull aching, which progresses to burning and excruciating pain that may require general anesthesia
The specific neural and metabolic factors responsible for tourniquet pain are still unknown, but researchers have identified the nerve fibers responsible for transmitting the impulses:
Small and slow unmyelinated C fibers:
Responsible for burning and aching
Large, fast myelinated A-delta fibers:
Responsible for pinprick, tingling, and buzzing sensations
Small and slow unmyelinated C fibers responsible for
burning and aching
Large, fast myelinated A-delta fibers are responsible for
pinprick, tingling, and buzzing
*True/False: Properly placed tourniquets inflated to appropriate pressures rarely cause injury
TRUE!
Prevention of post-op parasthesias
Use of proper padding
Appropriate choice of tourniquet size
Following recommendations for appropriate tourniquet pressure and usage time minimizes the incidence of complications
Goals of patient positioning
Optimal exposure of the surgical site
Protect all body systems
Enable appropriate monitoring throughout the procedure
Provide good access to the patient’s airway
Allow for comfort and warmth
Minimize or prevent physiologic functioning compromise
Protect all body systems
Maintain patient dignity
How is arthroscopy managed?
Can be managed by any available anesthetic technique:
General anesthesia
Combined regional and general anesthesia
Local blockade with sedation
Positioning for arthoscopy
Lower extremity arthroscopy:
Most often the supine position
Shoulder arthroscopy:
Lateral decubitus or “beach chair” position
Elbow arthroscopy:
Supine, lateral decubitus, or prone
What are the complications of arthoscopy?
Subcutaneous emphysema
Pneumomediastinum
Tension pneumothorax
Fluid volume overload due to irrigation fluid
What are the benefits of arthoscopy?
Minimally invasive, reduced blood loss, less post-op discomfort, reduced length of rehab
Signs and Symptoms of Tension Pneumothorax
Sudden, inexplicable hypoxemia
Elevated central venous pressure (CVP)
Tachycardia
Absent breath sounds on the affected side
Cyanosis
Diaphoresis
Decreasing oxygenation
Tracheal shift (away from the pneumothorax)
Agitation (may be observed in patients receiving regional anesthesia)
Hypotension
Jugular vein distention
Increased airway pressure
Asymmetric chest wall movement
Percussive hyperresonance over the affected side
Extreme anxiety (may be observed in patients receiving regional anesthesia)
Position related complications of beach chair
hypotension and bradycardia with interscalene blocks
air embolism/pneumo
DVT
unilateral vision loss
cerebral hypoperfusion
cervical plexus and hypoglossal nerve neurapraxias
Position related complications of lateral decubitus
temporary parasthesia
neurapraxis of the dorsal digital nerve of the thumb and musculoscutaneous, ulnar, axillary nerves
permanent neuropraxia
post-op stroke
DVT
fluid-related airway compromise
How to prevent position injuries with these..
beach chair - use level of brain systolic, attention to head positioning, prophylaxis for hypotensive bradycardic episodes
lateral decub - 45 degrees of forward flexion with 90 degrees abduction
45 degrees forward flexion with 0 degrees abduction
general anesthesia for longer cases
place anterior inferior portal out of traction
Arthroplasty terms
Total Arthroplasty:
Replacement of all of the joint
Hemiarthroplasty:
Replacement of part of the joint
Joint materials:
Originally stainless steel
Currently use nonferrous metal alloys (cobalt or titanium)
What is the most common approach for hip surgery?
Posterior approach
Requires a large incision extending from near the iliac crest across the joint to the midthigh level
What is the purpose of the direct anterior approach for hip surgery?
Minimally invasive, muscle-sparing approach with shorter incision
Benefits:
Shorter hospital stay
Faster postoperative recovery
What is the positioning for the two methods of hip surgery?
Posterior approach: Lateral decubitus
Anterior approach: Supine
Are hip surgery patients at an increased risk for VTE, DVT, and P.E’s?
Yes.
Treatment up to 35 days
Prevention of VTE:
Anticoagulation therapy (i.e, LMWH)
Intermittent pneumatic compression device (IPCD) for 10-14 days
What is the prevention for DVT/PE with hip surgery?
Anticoagulation therapy (i.e, LMWH)
Intermittent pneumatic compression device (IPCD) for 10-14 days
Treatment up to 35 days
What facilitates the surgical process for hip arthroplasty?
The muscle relaxation produced by a subarachnoid block (SAB)
What type of anesthesia is common for total hip arthroplasty?
Regional anesthesia is common
What is bone cement implantation syndrome (BCIS)?
Hypoxia, hypotension, cardiac arrhythmias, increased pulmonary vascular resistance and cardiac arrest
Methyl methacrylate (MMA) may be instilled into the femoral canal
Usually occurs at the following stages of surgery: femoral canal reaming, acetabular or femoral cement implantation, insertion of prosthesis or joint reduction, and occasionally after tourniquet deflation
*What is the first sign of clinically significant BCIS?
absence of EtCO₂ in a patient under general anesthesia
What are the clinical features for BCIS in the awake patient under regional anesthesia?
dyspnea and altered sensorium
What is the treatment for BCIS?
Increase FiO₂ to 100%
Aggressive fluid resuscitation
Treat hypotension with α-agonists
What increases the risk of getting BCIS?
Preexisting cardiovascular disease
Preexisting pulmonary hypertension
American Society of Anesthesiologists (ASA) class III or higher
New York Heart Association class 3 or 4
Canadian Heart Association class 3 or 4
Surgical technique
Pathologic fracture
Intertrochanteric fracture
Long-stem arthroplasty
Risk of BCIS increased by what during total knee arthroplasty?
Both FEMORAL and TIBIAL surfaces are covered with MMA cement
The high-density polyethylene patellar component is cemented and seated with a vise-like clamp
Are tourniquets used during total knee arthoplasty and ankle arthroplasty?
Yes
DVT, PE and fat embolus are a risk of ankle arthroplasty thromboprophylaxis
Most popular intraarticular procedures for ankle arthroplasty
Osteochondral lesion
Ankle or subtalar debridement
Subtalar fusion
Partial talectomy
Most common extraarticular procedures
Os trigonum excision
Tenolysis of the flexor hallucis longus tendon
Endoscopic partial calcanectomy
Anesthetic Management of Knee and Ankle Arthroplasty
Regional or General anesthetic (or a combination)
Regional anesthesia combining femoral and sciatic nerve blocks are sufficient for all surgeries below the knee that do not require a thigh tourniquet
The femoral nerve innervates the medial leg to the medial malleolus
The common peroneal and tibial nerve (branches of the sciatic nerve) innervate the rest of the leg below the knee, including the foot
Regional anesthesia combining which nerve blocks are sufficient for all surgeries below the knee that do not require a thigh tourniquet?
Femoral and sciatic nerve blocks
Upper Extremity Arthroplasty: Shoulder Arthroplasty
Reverse Total Shoulder Arthroplasty provides a better treatment option for more complex pathologies, rotator cuff tears, and revision of failed TSA
Best for shoulders?
RTSA
Indications for TSA/RTSA:
Posttraumatic brachial plexus injuries
Paralysis of deltoid muscle and rotator cuff
Chronic infection
Failed revision arthroplasty
Severe refractory instability
Proximal humerus fracture
Bone deficiency after resection of a tumor in the
proximal aspect of the humerus
What are the two goals of TSA/RTSA?
Pain reduction and Improved range of motion
Positions for shoulders
beach chair and lateral decubitus
Why are shoulder associated with more blood loss?
Because you can’t use a pneumatic turniquet
Elbow arthroplasty positions
supine, lateral, prone
Indications for elbows
Rheumatoid arthritis
Traumatic arthritis
Ankylosis of the joint
Goals for elbows
Pain reduction
Improved joint function
What type of anesthesia do you use for upper extremity arthroplasty?
Supraclavicular block or interscalene block
Combined general/regional anesthesia commonly used
Anesthetic considerations for upper extremity arthroplasty
Be vigilant re: the risk of extubation
Surgical manipulation can increase risk of cervical injury
Monitor patient’s eyes for pressure throughout the procedure - consider foam goggles
Beach chair issues with upper extremity arthroplasty
Pulmonary function will resemble more “normal” function than lateral position
Increased risk of venous air embolism
*Reaming of the shaft of the humerus leads to risk of fat or bone marrow embolism
Cerebral ischemia can occur with hypotension
Significant hydrostatic gradient between the brain and the site of BP measurement
**Approximately 2 mm Hg per 1 inch of height differential
*What is the difference between arm cuff measurement and brain pressure with beach chair?
**Approximately 2 mm Hg per 1 inch of height differential
What leads to risk of fat or bone marrow embolism in beach chair position with upper extremity athroscopy
*Reaming of the shaft of the humerus leads to risk of fat or bone marrow embolism
Postoperative visual loss
A result of intraoperative cerebral ischemia due to hypotension
What defines Hypotensive bradycardic episodes (HBEs)
Decrease in HR of at least 30 bpm within a 5-minute interval, any HR < 50 bpm
and/or a decrease in systolic BP of more than 30 mm Hg in a 5-minute interval or any systolic BP < 90 mm Hg
What is the most common mechanism of hypotensive bradycardic episodes?
The Bezold-Jarisch Reflex
Hypotensive Bradycardic Episodes (HBEs) and the bezold-jarisch reflex
An inhibitory reflex mediated through cardiac sensory receptors with a vagal efferent limb.
Clinically, the Bezold-Jarisch reflex is an inhibitory reflex usually denoted as a cardioinhibitory reflex defined as bradycardia, vasodilation, and hypotension resulting from stimulation of cardiac receptors
In the beach chair position, venous pooling in the lower extremities leads to an increase in sympathetic tone and ultimately a low-volume, hypercontractile ventricle
Cardiac hypercontraction leads to activation of the Bezold-Jarisch reflex with an abrupt autonomic withdrawal of sympathetic response and activation of increased vagal tone
The combination of venous pooling and paradoxical increased vagal tone results in sudden, profound bradycardia and hypotension that can be difficult to reverse rapidly
*Prophylaxis of HBEs
Aggressive treatment of fluid deficits and blood loss
Minimize venous pooling in the beach chair position with support stockings
With regional anesthesia, avoid use of local anesthetics using epinephrine
- Absorbed slowly, mimicking low-dose IV
epinephrine administration
- Increased cardiac contractility
- Resulting in ventricular emptying
- Increased heart rate (which reduces cardiac
filling)
- Increased peripheral vasodilation and pooling
(decreased afterload)
- Resulting in ventricular hypovolemia with
hypercontraction
Consider intraoperative β-blockade in select patients
Most common position for spinals
prone
Most Common Indications for spines:
Intervertebral disc herniation
Spinal stenosis
Scoliosis
Laparoscopic approach
Contraindications for spinal surgery:
Abdominal adhesions
Abdominal trauma
Severe cardiac or pulmonary disease (may not tolerate hypercarbia from insufflation)
Thoracic approach contraindicated in patients that cannot tolerate one lung ventilation
Patients requiring extensive instrumentation of the anterior spine
Anesthetic Challenges for spinal surgery
Airway control
Positioning
Fluid and blood transfusion management
Hemodynamic control
Postoperative analgesia
Advantages for laparoscopy for anterior spinal surgery
Slide 30.
So many things.
Shorter rehab, better view, decreased infection, better cosmetics, etc.
Anesthesia for spines
General
Patient Positioning for spines
Prevent eye injury/corneal abrasions
Use rolls or positioning devices to prevent abdominal compression in the prone position to prevent:
- Displacement of organs (including diaphragm) cephalad
Reduced functional residual capacity (FRC)
Reduced tidal volume (TV)
Increased airway pressures
Engorgement of the epidural venous network
Contributes to increased blood loss
Symptoms of aortic injury during a spine
Suspect with sudden, dramatic, unanticipated, sustained hypotension
Main causes of post-op visual loss
Ischemic optic neuropathy
Retinal vascular occlusion
Spinal Surgery: Postoperative Visual Loss (POVL) risk factors
Male sex
Obesity
Use of Wilson frame
Anesthesia duration > 6 hours
Large blood loss
Colloid as percent of nonblood fluids
Spinal Surgery: Postoperative Visual Loss facts
Visual loss occurs 24 to 48 hours after surgery
Usually bilateral
Painless vision loss
Afferent pupil defect or nonreactive pupil
No light perception
Decreased or absent color vision
Elevated intraocular pressures (IOP) > 40 mm Hg
Positioning to avoid visual loss during spines
Position patient’s head in a neutral position level with or above the heart
Use a foam headrest
Do NOT cover the eves with goggles when using a square foam headrest
Perform and document eye checks every 20 minutes
Recommendations from task force for visual loss
- Consider informing patients who will undergo spine operations in the prone position anticipated to involve prolonged duration and/or substantial blood loss that they have a small but unpredictable risk of perioperative visual loss.
- Continually monitor systemic blood pressure.
- Colloids should be used along with crystalloids for maintaining euvolemia.
- Hemoglobin or hematocrit values should be monitored periodically during surgery, but no optimal transfusion threshold to prevent perioperative visual loss has been identified.
- The decision to use α-adrenergic agents should be made on a case-by-case basis.
- Direct pressure on the eye should be avoided to prevent central retinal artery occlusion.
- Position the head in a neutral position with the face down and the head level with or higher than the heart to minimize venous outflow obstruction.
- Consider staging very prolonged procedures in high-risk patients with careful consideration of the risk: benefit ratio.
- Assess vision when the patient becomes alert.
- An urgent ophthalmologic consultation should be obtained if there is concern for postoperative visual loss.
- Consider optimizing hemoglobin, hematocrit, hemodynamic status, and arterial oxygenation.
- Consider magnetic resonance imaging to rule out intracranial causes of visual loss.
- Antiplatelet agents, steroids, or intraocular pressure–lowering agents have not been shown to be effective for treatment of perioperative ION.
Foot and Ankle Surgery
Most common ankle procedures:
Repair of ankle fracture
Ankle fusion
Achilles tendon repair
Most common foot procedures:
Bunionectomy
Hammertoe correction
Plantar fasciotomy
Anesthetic Management:
Regional anesthesia
MAC anesthesia
General anesthesia
Forearm and Hand Surgery
Indications:
Fractures
Nerve compression (carpal tunnel release)
Anesthetic Management:
Full stomach? (traumatic injury)
Regional anesthesia
IV regional (Bier block)
Brachial plexus block
Tourniquet pain with prolonged procedure and regional anesthesia
MAC anesthesia
General anesthesia
Rheumatoid Arthritis (RA):
The most prevalent chronic systemic inflammatory disease
Autoimmune disease
Signs and symptoms:
Joint swelling
Joint tenderness
Destruction of synovial joints
Anesthetic concerns:
Airway!
- Effects on cervical spine, temporomandibular
joint, larynx, and pulmonary system
- Limited ROM
*Cricoarytenoid joints are common sites for rheumatoid nodule deposition
Ankylosing Spondylitis (AS):
Chronic inflammatory process
Primary target: Spinal column and surrounding tissues
Additional effects:
- Cardiac valve dysfunction
- Conduction delays
- Bundle branch blocks
- Restrictive lung disease
Anesthetic Management:
Airway!
- Position patient so no neurologic symptoms
are present prior to induction of anesthesia
- Cervical spine in neutral position
Regional anesthesia is a safe approach
