AP 2 Test 4 Flashcards
What vessel supplies the anterior 2/3rds of the spinal cord with blood
Anterior spinal artery
From what vertebral levels does the Artery of Adamkiewicz stem from in the majority of patients (60%)?
T9-T12
What is a collective term for disorders of the spinal cord?
Myelopathy
What is a collective term for disorders of the spinal nerve roots?
Radiculopathy
Between which layers of the spinal cord are the vessels supplying the cord with blood located?
Between the arachnoid and pia mater
What is spina bifida
Failure of fusion of one or more vertebral arches
What is special about the anatomy of the vessels in the vertebral plexus?
They are valveless
Which vertebrae do the vertebral arteries travel through?
C1-C6
Which directions do most herniations of the spinal cord occur in?
Posteriorly and laterally b/c the posterior ligament is not very wide
What is important to ask pre-op when assessing pain of a patient presenting for a spinal surgery?
Where their pain is and what medication they are taking for it
Which table used in spinal surgeries helps decompress the epidural veins and prevent bleeding?
Jackson table
What is the most common intubation technique for a C1-C2 fusion surgery?
Fiberoptic intubation
What are the extubation considerations for a C1-C2 fusion surgery?
Delayed extubation so swelling can go down
What is an important structure that the surgeon must be careful of during an ACDF that could injure the patient’s airway if damaged?
Recurrent laryngeal nerve
What is a cervical laminoplasty?
A small section of the lamina is moved to expand the spinal canal to relieve pressure on the spinal cord or nerves
What test is done after a posterior cervical fusion to test dural closure?
Valsalva
What airway device may be needed during thoracic spine reconstruction and fusions of the T1-T8 spine?
Double lumen tube
What is scoliosis?
Lateral curvature and rotation of vertebrae
What measurement indicates the severity of respiratory impairment due to scoliosis?
Cobb angle
The lungs develop until what age?
8
How is FEV1/FVC affected in a patient with scoliosis?
Not affected - normal ratio
What pulmonary pattern presents on a flow-volume loop of a patient with scoliosis?
Restrictive
A patient with scoliosis has a vital capacity that is __-__% the normal value
60-80%
How does scoliosis affect lung volumes?
Decreased TLC, FRC, inspiratory capacity, expiratory reserve
Worsening pulmonary function due to scoliosis has to do with what aspects of the disease?
- How many vertebrae are involved
- How cephalad the discurvature lies
What cardiovascular issues occur in patients with scoliosis?
- Pulmonary HTN
- Right ventricular hypertrophy
- Mitral valve prolapse
- Cardiomyopathy
What pre-op workups are standard for almost every scoliosis surgery?
- CBC
- Type and screen
- Chest X ray
What pre-op test is needed if a patient with scoliosis has a history of pulmonary HTN?
ABG
What is a common anesthetic plan for patients with osteoporosis coming for a kypho- or vertebro- plasty?
Prone MAC
What huge nerve creates pain in the lower back and hip and down the back of the thigh when it is impinged?
Sciatic nerve
Vertebral roots of the sciatic nerve
L4-S3
If there is a spinal cord herniation between L4 and L5, which nerve root is being compressed?
L5
Most surgeons want a MAP above __ during lumbar fusion/laminectomies to maintain spinal cord perfusion
80
What regions of the spinal cord are the largest?
Cervical and lumbosacral b/c they’re innervating the limbs
Somatosensory evoked potentials monitor what part of the spinal cord?
Posterior cord
Motor evoked potentials monitor what part of the spinal cord?
Anterior cord
What nerves are stimulated during SSEP?
- Median
- Ulnar
- Posterior tibial
What spine surgeries use evoked potentials?
- Scoliosis
- Laminectomy w fusion
- Fractures
- Cord tumor
What MAC level can be run when monitoring SSEPs?
0.5-1 MAC
How does propofol affect SSEPs?
- Decreases amplitude
- Increases latency
How does etomidate affect SSEPs?
- Increases amplitude
- Increases latency
How does ketamine affect SSEPs?
Increases amplitude
How does nitrous affect SSEPs?
Decreases amplitude
Where is stimulation occuring during MEP?
Transcranial stimulation
What airway adjunct must you use during MEPs to avoid a swollen tongue?
Bilateral bite blocks
Where is the response to SSEPs monitored?
In the brain
Where is the response to MEPs monitored?
Hands, feet, teeth
During which evoked potential monitoring can you not use NMB?
Motor
What is the max MAC level you can use during MEP monitoring?
0.5 MAC
What anesthetic technique is commonly used when monitoring MEPs?
TIVA
What does spontaneous EMG monitor?
Muscle activity in a specific peripheral nerve when stimulated
What nerve is stimulated with a NIMs tube?
Recurrent laryngeal nerve
What is the purpose of triggered EMG?
To determine whether a pedicle screw is properly located
When should you considering setting up blood for spinal surgeries?
- When the patient has a tumor b/c usually you cannot use cell saver
- Multiple redo
- Multilevel surgery
- If surgeons are working near great vessels
- If the patient is anemic
- ESRD
What is spinal shock?
Flaccid paralysis below a spinal cord injury that causes loss of sensation and vascular reflexes
How are vitals affected when a patient has spinal shock?
Hypotension and bradycardia due to increased vagal tone
If a patient with spinal shock does not have tachycardia in response to hypovolemia, you know the injury occurred at what levels
T1-T4 - cardiac accelerators
Patients with spinal shock can only have succinylcholine in the first __ hours of the injury
48
When does hyperkalemia due to spinal shock peak?
2 weeks
How should CO2 levels be maintained in a patient with spinal shock?
Avoid hypocarbia because that will decrease spinal blood flow
Autonomic hyperreflexia can occur with a complete transection above what spinal level?
T6
What is autonomic hyperreflexia?
Vasoconstriction below the level of a spinal transection but vasodilation above the transection - occurs after spinal shock has worn off and is set off by a stimulation below the level of the injury
What are the cardiovascular signs of autonomic hyperreflexia?
Hypertension with bradycardia
Treatment for autonomic hyperreflexia
- Stop surgery
- Deepen anesthetic
- Nitroglycerin
Which spine surgeries have the highest incidence of post-op blindness
- Scoliosis
- Posterior lumbar fusion
How does ischemic optic neuropathy occur (ION)?
Decreased blood supply and O2 delivery to the optic nerve
What type of ION is more common after spine surgeries?
Posterior
Patients in the prone position are at risk of what eye injury?
Central retinal artery occlusion
What treatments are available for central retinal artery occlusion?
- Stellate ganglion block
- Ocular massage
- Acetazolaminde
- 5% CO2 in oxygen inhaled
- Local hypothermia
What are the surgical risk factors for post-op vision loss?
- Prone positioning
- Wilson frame
- Prolonged robotic surgery with head down
- Surgery greater than 6 hours
- EBL greater than 1 liter
What is the anesthetic risk factor for post-op vision loss?
Decreased percent colloid
What are the patient risk factors for post-op vision loss?
- Male
- Obese
What are the ASA’s recommendation for avoiding post-op vision loss?
- Decrease venous congestion and edema in the head
- Keep head at or above level of the heart
- Include colloid in fluid replacements
Venous air embolism is most common in what position?
Sitting
What methods can we use to detect venous air emboli?
- TEE
- Precordial doppler
- Mill wheel murmur
Cardiovascular signs of a VAE
- Hypotension
- Tachycardia
- Increased PA pressure
- Decreased cardiac output
Effect of VAE on saturation
Decreases saturation
Effect of VAE on end tidal gases
- Decreased ETCO2
- Exhaled nitrogen
Treatment of VAE
- Flood field with fluid
- 100% O2
- Aspirate if you have CVP
- Fluid bolus
- Pressors
- Jugular compression to prevent further entrainment
- CPR
What position is used to treat VAE
Left side down
What should be included in your post-op assessment of a patient who’s undergone spinal surgery?
- Edema of face/eyes
- Vision
- Position
- Neuro exam
What are the risks involved in laser surgery for ENT cases?
- Airway fires
- Eye injury
What are the risks associated with jet ventilation techniques used in ENT surgery?
- Hypercapnia
- Barotrauma
What risks are associated with fiberoptic intubations used for ENT surgery?
A failed intubation means an emergency surgical airway is the backup
What risks are associated with nasal intubations?
Epistaxis
What risk is associated with TIVAs used for ENT surgery?
Awareness
What risk is associated with controlled hypotension in ENT surgeries?
Ischemia
What abnormal patient characteristics are commonly found in ENT?
- Head/neck cancers
- Limited c-spine ROM
- Decreased mouth opening
- Decreased tissue compliance
- Receding jaw
- Distorted airway anatomy
- Vocal cord dysfunction
- Large tongue
How should analgesia be managed for most ENT surgeries?
Good intraop and postop analgesia is necessary because most procedures are performed on highly reflexogenic areas
It’s common to keep the patient’s systolic pressure under ___ mmHg to maintain a bloodless field for ENT surgeries
100
What is the goal MAP for patient’s undergoing ENT surgery in order to maintain a bloodless field?
60-70
What are the various types of endoscopies used in ENT surgeries?
- Laryngoscopy
- Microlaryngoscopy
- Esophagoscopy
- Bronchoscopy
What are common indications for endoscopies?
- Voice disorders
- Stridor
- Hemoptysis
What are pre-op considerations for endoscopies?
- Focus on H&P to look for any potential airway problems
- Review prior notes and imaging from ENT clinic
If you aren’t expecting to be able to easily mask ventilate or DL your patient in an ENT surgery, what should be done?
Secure the airway before induction with a fiberoptic bronchoscope or awake tracheostomy
What are the critical steps when preparing for a fiberoptic intubation?
- Have patient mentally and pharmacologically prepared
- Have ALL equipment prepared
- Make sure the ENT surgeon is in the room so they can assist
What is the dose of atropine when used as an antisialagogue for fiberoptic intubation?
0.5-1mg IV or IM
What is the dose of glycopyrrolate when used as an antisialagogue for fiberoptic intubation?
0.2-0.4mg IV or IM
What is the loading dose of dexmedetomidine when used as a sedative?
1mcg/kg over 10 min
What is the infusion dose of dexmedetomidine when used for sedation?
0.2-0.7mcg/kg/hr
Dose of Alfentanil
100-1000mcg IV
When should antisialogogues be given for a fiberoptic intubation?
20-30min prior to airway manipulation
1 side effect of dexmedetomidine
Bradycardia
Which commonly used antisialogouge crosses the blood brain barrier and can cause psychosis, confusion, and dizziness?
Atropine
What are the advantages to using Afrin nasally before local topicalization for nasal intubation?
It provides vasoconstriction and keeps the lidocaine from getting absorbed systemically
How should lidocaine swabs be used before a fiberoptic intubation?
Swab the patient’s nose with 2-4% lidocaine and leave for 5-15 minutes before intubation
What cranial nerve innervates the nasal cavity and turbinates?
Trigeminal
What are the topicalization options available for the oropharynx and larynx?
- Gargle with lidocaine
- Benzocaine spray (hurricaine)
- Facemask or oral nebulizer with 2-4% lidocaine
- Lidocaine ointment to posterior pharynx with tongue depressor
- Trans-tracheal block
What issue can occur when too much hurricane (benzocaine) spray is applied?
Methemoglobinemia
What membrane is pierced during a trans-tracheal block?
Cricothyroid membrane
What cranial nerve innervates the oropharynx and posterior third of the tongue?
Glossopharyngeal
What cranial nerve innervates the epiglottis and more distal airway structures?
Vagus
How must muscle relaxation be managed for a laryngeal endoscopy?
There must be masseter muscle relaxation until the end of the case, can be achieved with intermittent non-depolarizing blockade boluses or a SUX infusion
What can occur if you run a sux infusion too long?
You can get a Phase II blockade and the sux will act like a non-depolarizing blockade
What tube is often used for a laryngeal endoscopy?
Specialized microlaryngoscopy tube
What is special about a specialized microlaryngoscopy tube?
- Longer than standard ETT tube
- High volume/low pressure cuff
- Stiffer so it is less prone to compression
What is the issue with jet ventilation that you must be very careful with?
It does not ensure ventilation so you must be very careful to allow a full exhalation by watching the chest rise and fall completely
How long and at what pressure should inspiration with a jet ventilator be administered?
1-2 seconds at 30-50psi
How long should you allow for expiration after a breath with a jet ventilator?
4-6 seconds
What anesthetic method is required when using jet ventilation?
TIVA
What monitor is not available when using jet ventilation?
ETCO2
What cardiovascular considerations should be accounted for during a laryngeal endoscopy?
There are alternating times of extreme stimulation and no stimulation so there is frequent alternations between hypo- and hyper- tension
What are the advantages of a metal ETT tube used for laser surgery?
- Combustion resistant
- Kink resistant
- Double cuff
What are the disadvantages of a metal ETT tube used for laser surgery?
- Thick walled
- Transfers heat
- Reflects laser beams
What are the advantages of a silicone ETT tube used for laser surgery?
- Small
- Non-reflective
- Atraumatic
What are the disadvantages of a silicone ETT tube used for laser surgery?
- Silicone is combustible
- Teflon ignition=toxic ash
- Metal foil can unwrap and cause occlusion of airway
What is the ideal FiO2 for laser surgery?
21%
What should be placed in the airway during laser surgery to limit risk of ETT ignition?
Saline-soaked pledgets
What is the fire triad?
1) Oxidizer (O2, N2O)
2) Ignition source (laser, scopes, surgical devices)
3) Fuel (ETT, gauze, alcohol solutions)
What should be done when an airway fire occurs?
1) Stop the procedure
2) Stop ventilation and flow of all airway gases
3) Remove the tube and flammable materials
4) Pour saline in patients airway
5) Ventilation with facemask on room air
6) Reintubate as soon as you can
What are special pre-op considerations for nasal and sinus surgeries
- Could be a difficult mask ventilation
- Asthma/allergic disorders
- Recent use of ASA/Plavix
What airway equipment is often needed for nasal and sinus surgeries?
- Oral airway during mask ventilation
- Oral RAE
What are positioning considerations for nasal and sinus surgeries?
- Arms often tucked
- Slight head up positioning (make sure patient doesn’t have risk factors for CVA)
Extubation technique for nasal and sinus surgeries
Usually deep extubation
Why is the NIMs tube often used for anterior neck surgeries?
To preserve superior laryngeal, recurrent laryngeal, and vagus nerve branches
How does the NIMs tube work?
Stimulates motor nerves and records EMG response
How should NIMs ETT be secured?
Midline
What muscle relaxants can be used with a NIMs tube?
Sux - NO non-depolarizers!!
Pre-op considerations for head/neck cancer surgeries
- Abnormal airway
- Obstruction lesions
- History of radiation
- May need awake fiberoptic/tracheostomy
Flap protocol at EUHM states to keep crystalloid fluids under __ liters
5
Flap protocol at EUHM states to keep PRBC administration under __ units
3
Flap protocol at EUHM states to keep albumin administration under __ liters
2
Flap protocol at EUHM states to keep operative time under __ hours
10
What are the potential contraindications for immediate post-op extubation according to flap protocol at EUHM?
- Over 75 years old
- Asa 4+
- CV unstable
- Current alcohol abuse
- Greater than 7L fluids intraop
- Major pharyngeal reconstrution
Lines/access necessary according to flap protocol at EUHM
- 2 peripheral IVs 18G or larger
- A line
Where should the a-line transducer be zeroed for a flap procedure?
At the level of the brain
What nerves need to be preserved during a flap procedure?
Facial and spinal accessory
When is it okay to remove anesthesia’s ETT during a tracheostomy?
After correct positioning is confirmed by ETCO2 and chest movement and/or auscultation by the surgeon
What could be causing increased PIPs after a tracheostomy?
- Malpositioned tube
- Bronchospasm
- Debris/secretions in trachea
- Pneumothorax
Intraop considerations for maxillofacial reconstruction and orthognathic surgery
- Long procedure with high EBL
- Throat pack in place
- Head up positioning
- Controlled hypotension
- Local infiltration with epi solutions
- Laser precautions
What gas is rarely used for ear surgeries?
N2O
What is a post-op risk of ear surgeries?
Increased PONV and vertigo, fall risk
How can we decrease risk of PONV from ear surgeries?
- Propofol drip
- Decadron
- Zofran
What nerve comes out from under the earlobe and innervates the orbicularis oculi?
Facial
What causes a “brain stem anesthetic” that can occur during a retrobulbar block?
There is a subarachnoid space in the orbit, so there can be inadvertent local injection into this space in the eye that will travel to the brain stem
How soon after injection do signs of a brain stem anesthetic show up?
4-7 minutes after injection
What are the most common symptoms of a brain stem anesthetic?
Patient becomes apneic and unresponsive
At the least, what monitor should be used when placing a retrobulbar block?
Pulse ox
Functions of the ciliary body
- Secrete aqueous humor
- Fatten/thin lens to accommodate and focus light
What are the long term effects of undiagnosed/treated glaucoma?
It can lead to optic nerve atrophy and causes a shrinking of the visual field until full blindness occurs
What supplies the back of the eye with blood?
Choroid plexus
What is normal intraocular pressure
Less than 22mmHg
How much phenylephrine is contained in 1 drop of 10% phenylephrine?
7mg
3 determinants of intraocular pressure
1) Extrinsic pressure
2) Scleral rigidity
3) Alteration of intraocular contents
What structure divides the eye into anterior and posterior chambers?
Iris
What are the 2 most important determinants of intraocular pressure?
- Rate of formation
- Drainage
4 contributors to increased intraocular pressure
- Acute HTN
- Hypoxia
- Hypercarbia
- Succinylcholine
Contributors to decreased intraocular pressure
- Inhaled anesthetics
- CNS depressants
- ND-NMBs
- Hyperventilation
- Hypothermia
- Ganglionic blockers
- Diuretics
Afferent nerve in the oculocardiac reflex
Trigeminal (opthalamic branch)
Efferent nerve in the oculocardiac reflex
Vagus
What events can set off the oculocardiac reflex?
- Pressure on the globe
- Retrobulbar block
- Pressure on orbital contents after enucleation
- Traction on EOM
- Ocular trauma
Most common side effect of oculocardiac reflex
Bradycardia
Effects from oculocardiac reflex
- Bradycardia
- V tach
- V fib
- Sinus arrest
- Asystole
Treatment of oculocardiac reflex
Ask the surgeon to stop - symptoms will quickly end
Anesthetic method for cataract surgery
Very minimal sedation
What is the issue with using succinylcholine for strabismus procedures?
It causes contractions of the muscle that prevent forced duction testing
What is forced duction testing?
Tests to see how well the eye moves and if there is tension in the extraocular muscles
Patients with strabismus are susceptible to what intra-op crisis?
MH
Strabismus surgery is one of the major risk factors for ____ due to oculo-gastric reflex
PONV
What glaucoma medications should we be aware of when managing a patient for glaucoma surgery?
- Timolol - a nonspecific beta blocker that decreases production of aqueous humor, but can get systemic absorption and get bronchospasm and bradycardia
- Pilocarpine
- Meds with epi
What block is used for glaucoma and retinal detachment surgeries?
Opthalamic block
Intraocular gas used for retinal detachment surgery
Sodium hexaflouride
Most common eye injury in ophthalmic surgery
Corneal abrasion
What is the result of patient movement during eye surgery?
Blindness
What is expulsive subchoroidal hemorrhage?
Sneezing or coughing with the eye open forces the retina outward and squeezes eye contents through the anterior eye wall
Additive in local anesthetic for retrobulbar block to penetrate fat surrounding the eyeball
Hyaluronidase
Needle used for retrobulbar and peribulbar blockers
Single bevel flat-ground needle
Why is a retrobulbar block like a spinal?
Low volume and rapid onset
Which facial nerve block only supplies the orbicularis oculi?
Van Lint
What block for eye surgery avoids injection into the muscle cone and lowers the risk of globe perforation?
Peribulbar block
Advantages of peribulbar block
- Avoids need for facial nerve block
- Avoids muscle cone injection
- Lowers risk of globe perforation
- Direct effect on orbicularis oculi
Disadvantages of peribulbar block
- Requires large volume
- Frequently requires supplementation
Indications for peribulbar block
- Long axial length (near-sighted)
- Previous extra-ocular surgery
Patients with spherical correction less than ____ need a peribulbar block
-5.00D
Normal axial length
20-22mm
Appropriate sedation level for a patient getting an eye block
- Arousable
- Responds to verbal commands
- Not moving
Sedation techniques for eye blocks
1) Give small amounts of versed and fentanyl then titrate in propofol until patient is breathing but doesn’t respond
2) Give small amounts of fentanyl and versed and give incremental doses of alfentanil (~3-5cc at 1000mcg/cc), monitoring patients respiratory rate and level of consciousness
Which type of pain, chronic or acute, is associated with neuroendocrine stress?
Acute pain
How long can pain persist and still be labeled “acute pain”
3-6 months
What term is defined as “a state of adaption in which exposure to an opioid drug induces changes that result in a decrease of the drug’s effect over time”?
Opioid tolerance
What is opioid induced hyperalgesia (OIH)?
Prolonged administration of opioids results in a paradoxic increase in atypical pain that appears to be unrelated to the original nociceptive stimulus
What is the treatment for OIH?
Decrease opioid administration and work in something that is not working strictly at Mu receptors, such as ketamine
What is the most prescribed opioid?
Tramadol
What schedule is Tramadol?
Schedule IV
What is Actiq?
A fentanyl lollipop that is very short acting
What are the receptor actions of Methadone (Dolaphine)
Mu agonist, NMDA antagonist
How long does it take for Methadone to reach a steady state for its analgesic action?
5-7 days
Why is there a black box warning for Methadone?
Respiratory depression when combined with short acting narcotics
How does Methadone affect cardiac conduction/EKG in doses over 60mg?
- Prolongs QT interval
- Torsades de Pointes
What opioid is contained in a Duragesic patch?
Fentanyl
What is the black box warning for Duragesic patch?
Don’t give unless the patient has been taking…
- 60mg Morphine
- 30mg Oxycodone
- 8mg Hydromorphone for a WEEK or longer
When is the Duragesic patch contraindicated?
- Acute pain
- Post-op pain
Opioid side effects
- Resp. depression
- Sedation
- Confusion
- Pruritus
- N/V
- Constipation
- Urinary retention
- Myosis
- Muscle twitching
What are the receptor actions of ketamine?
- Mu agonist
- Non competitive antagonist at the NMDA receptor
What metabolite of ketamine can cause prolonged analgesic action?
Norketamine
“GINTL” (gin and tonic with lime) encompasses which non-opioid methods of pain management?
G - gapapentin/neuronitin I - ice N - NSAIDs (ketorolac, celebrex, ibuprofen) T - tylenol/acetaminophen L - lidocaine patches
How do the pupils look when a patient has taken narcotic analgesics such as heroin and various pain pills?
Pinpoint
How do the pupils look when a patient has taken meth, cocaine, ritalin, diet pills, or hallucinogens?
Very dilated
High doses of methamphetamine may induce what physiologic crisis
Malignant hyperthermia
How much does an epidural allow the dosing of narcotics to decrease?
1/10th the dose
Benefits of an epidural
Decreases….
- Post-op resp. complications
- Incidence of post-op MI
- Stress response to surgery
- Blood transfusion requirements
Surgical regions that indicate epidural placement
- Thoracic
- Abdominal
- Pelvic
- Lower extremity
Epidurals are contraindicated when the platelets are below…
100,000
Epidurals are contraindicated when what lab value is elevated and indicating infection?
WBC
What central nervous system diseases contraindicate epidural placement?
- Multiple sclerosis
- Syringomyelia
In what common surgeries is toradol a contraindication?
- Spinal surgeries
- Tonsillectomies due to the increase in bleeding
Appropriate dose of toradol for most patients older than 60 years old
15mg
An epidural can stay into place for up to…
2 weeks
Can a patient with a spinal nerve stimulator receive an epidural?
No
Can a patient with an intrathecal pump receive an epidural?
Yes
A dose of heparin cannot be given within __ hours of an epidural placement
6
Low molecular weigh heparins such as Enoxaprin, Dalteparin, Tinazaprin cannot be given within ___ hours of an epidural placement
24
How long before an epidural placement must Coumadin be discontinued
3-4 days
What lab must be checked before an epidural if the patient has been taking Coumadin
PT
How long before an epidural placement must the anti-platelet Ticlopidine be discontinued
14 days
How long before an epidural placement must the anti-platelet Plavix be discontinued
7 days
How long before an epidural placement must the direct thrombin inhibitor Dibigatran (Pradaxa) be discontinued?
5 days
How long before an epidural placement must the Factor Xa inhibitor Xarelto be discontinued?
9 hours
How long before an epidural placement must the Factor Xa inhibitor Arixtra be discontinued?
21 hours
Complications of epidural placement
- Infection
- Bleeding
- PDPH
- Nerve damage
- Hematoma
- Abcess
- Seizures
- Cardiac arrest
Side effects of opioids in epidurals
- Hypotension
- Sedation
- Pruritus
If a patient has opioids in their epidural, can you still give them opioids IV or PO?
No
Treatment of hypotension from an epidural in the recovery room
- Fluid bolus
- Hold or decrease epidural infusion
- Consider opioid only
What are some examples of surgeries that should have opioid only in their epidurals?
- AAA
- HIPECCS
- Lobectomy
Primary narcotics given in a spinal
Morphine, hydromorphone
Should a patient who comes into preop with a fentanyl patch take it off before they go back for surgery?
No
If a patient has intrathecal narcotics, they shouldn’t get more than ___ mcg of fentanyl during the case
250
Geriatric patients are defined as being __ years or older
65
Pharmacokinetic considerations in geriatric patients
- Decreased protein binding so higher unbound drug levels in the plasma
- Slower redistribution
- Increased elimination half life
*ALL LEAD TO INCREASED DRUG LEVELS AT TARGET ORGANS
Changes in body compartments in geriatric patients
- Loss of skeletal muscle/lean body mass
- Increased percentage of fat
- 20-30% reduction in blood volume
Changes in drug metabolism in geriatric patients
Drug metabolism slows because…
- Clearance decreases b/c liver blood flow, liver mass, and kidney function decreases
- Volume of distribution increases because of increased body fat and decreased albumin levels
In general, by what percentage should you reduce the dose of propofol for geriatric patients
20-50%
In general, by what percentage should you reduce opioid doses in geriatric patients
50%
How does the action of muscle relaxants change in geriatric patients?
The dose needed doesn’t change but it may take longer to see effects
How does the MAC values of volatile agents change per decade after 40?
MAC decreases by 6%
Considerations for benzodiazepine use in geriatric patients
They are more sensitive to CNS effects of drugs so if you are using them reduce the dose
Considerations for using anticholinergics and antihistamines in geriatric patients
Can lead to confusion and increased risk of post up delirium
What specific drugs should you consider avoiding in elderly patients
- Scopolamine
- Diphenhydramine
- Meperidine
How does aging affect arterial function?
- Loss of elasticity causes arterial stiffening
- Increased pressure in aortic root leading to increased SVR
- Can lead to ventricular hypertrophy and impaired diastolic filling
How does aging affect venous function?
- Veins stiffen
- Veins are less able to adapt to changes in blood volume
- Volume shifts can cause exaggerated changes in cardiac filling
Ventricular changes in geriatric patients
The ventricle stiffens and causes impaired lusitropy (rate of myocardial relaxation) which can lead to dependence on higher filling pressures
What is the most common cause of heart failure in patients over 75?
Diastolic dysfunction
Elderly patients have less responsiveness to which receptor?
Beta receptors - which decreases their increase in heart rate with stress
What cardiovascular qualities do NOT diminish with age?
- Intrinsic quality of the muscle (heart does not weaken due to age alone)
- Peripheral vasoconstriction (patients have enhanced sympathetic tone at rest)
How do elderly patient’s blood pressures tend to trend in response to anesthetics?
You are likely to see labile blood pressures - very high one minute and very low the next
How is vital capacity changed in elderly patients
Decreased vital capacity
How is residual volume changed in elderly patients
Increased residual volume
How is gas exchange in the airways changed in elderly patients?
- There is a breakdown of elastin connections in the lower airways, making them prone to collapse
- Decreased surface area for gas exchange
- Increased shunting
- Increased dead space
How does the time needed for adequate preoxygenation change in elderly patients?
Preoxygenation takes longer in elderly due to the increasing V/Q mismatch
Mean PaO2 in patients over 60
81 mmHg (71-91 range)
How is the ventilatory response to hypercapnia and hypoxia changed in elderly patients?
They have a blunted response, the change in minute ventilation in response to hypoxia/hypercapnia is about half of what it is in a healthy 25 year old
Airway changes in elderly patients
- Decreased C spine mobility
- Smaller mouth opening
- Smaller glottic opening (consider smaller tube)
- Fragile/missing teeth
- Decreased sensitivity of protective airway reflexes (increased risk of aspiration)
What factors make elderly patients more prone to hypoxia in the PACU?
- Longer time for preO2
- More difficult airway
- Lower PaO2
- Prone to airway collapse
- Increased work of breathing
- Slower drug clearance
Why are elderly patients more prone to hypo- and hyperthermia?
- Don’t vasoconstrict or shiver until temps are very low
- Lower resting metabolic rate
- Decreased ability to adjust peripheral and cutaneous blood flow
GI changes in elderly
- Decreased HCl
- Decreased saliva
- Decreased taste buds
Endocrine hormones that are decreased in elderly
- T3
- Testosterone
Endocrine hormones that are increased in elderly
- Insulin
- Norepinephrine
- Parathyroid hormone
- Vasopressin
Lab values that are changed in elderly patients
- Sed rate
- Creatinine
- Alkaline phosphatase
- PSA
- Serum iron
- Total iron binding capacity
What is a common finding in elderly patient’s urinalysis? Abnormal finding?
- Pyuria common
- Hematuria not normal
CNS structural changes in elderly
- Brain mass decreases
- Decreased cerebral blood flow
- Decreased CMRO2
- Decreased Ach, dopamine, NE
What is the most common manifestation of perioperative CNS dysfunction?
Post op delirium
What are the signs of post op delirium?
- Acute confusion
- Decreased alertness
- Misperception
- Agitation
Post op delirium is __ times as common in elderly patients when compared to younger populations
2
What factors pre-dispose geriatric patients to post-op delirium?
- Drug withdrawal
- Benzos
- Tricyclic antidepressants
- Anticholinergics
- Pre-existing depression/dementia
- Metabolic disturbances
What metabolic disturbances might cause post op delirium?
Abnormal levels of…
- Na+
- K+
- Glucose
- Albumin
- BUN/Cr
Strategies to reduce post op delirium
- Minimize benzos/anticholinergics/antihistamines
- Maintain BP greater than 2/3rds of baseline
- O2 sat greater than 90%
- Gct greater than 30%
Common treatable causes of post op delirium
- Hypoxemia
- Hypercarbia
- Hypotension
- Pain
- Sepsis
- Metabolic disturbances
Using Haloperidol to treat post op delirium is contraindicated in patients with what disease?
Parkinson’s
Post op cognitive dysfunction is more common in which types of patients?
1) Elderly
2) Less well educated
3) Previous history of CVA
Risk factors for POCD (post-op cognitive dysfunction)
- Advanced age
- Long operation
- Limited education
- Second operation
- Infection
- Respiratory complications
- Cardiopulmonary bypass
- Orthopedic surgery
Which pre-existing conditions make elderly patients at a significantly increased risk for POCD?
- MI within 6 months
- Pulmonary edema
- Unstable angina
- Aortic stenosis
What is the most important part of a medical history of elderly patients?
Assessing functional status
Which type of hypersensitivity reactions are cytotoxic
Type II
Which type of hypersensitivity reactions are delayed
Type IV
Which type of hypersensitivity reactions are immune complex reactions
Type III
Which type of hypersensitivity reactions are immediate
Type I
Examples of Type I hypersensitivity reactions
- Atopy
- Urticaria
- Angioedema
- Anaphylaxis
Examples of Type II hypersensitivity reactions
- Hemolytic transfusion rx
- HIT
Example of Type III hypersensitivity reaction
Serum sickness
Example of Type IV hypersensitivity reaction
Contact dermatitis
Signs of contact dermatitis (type IV rxn)
- Pruritus
- Red weepy skin
What is required in order for a type I anaphylactic reaction to occur
Prior exposure to antigen
Systems affected by type I anaphylactic reaction
- Cardiovascular
- Pulmonary
- Cutaneous
What mediates type I anaphylactic reactions
Antigen:antibody reaction of the immune system
Grade IV anaphylactic reaction
Cardiac arrest
What exposure causes the fastest and most severe anaphylactic reactions?
IV and mucous membrane
Risk factors for anaphylactic reactions
- Mastocytosis (large concentration of mast cells)
- Allergic to drug used
- Risk factors for latex allergy
- Atopy
- History of uninvestigated life threatening event
Mechanism of anaphylactic reaction
A susceptible person is exposed to an antigen and their body produces antigen-specific IgE antibodies against it. Re-exposure to this antigen results in mass release of chemical mediators from mast cells and basophils
What effect of anaphylaxis do histamine, leukotrienes, and prostaglandins all cause?
Bronchoconstriction
What is an anaphylactoid reaction
A reaction that is NOT dependent on IgE antibodies. Mast cells and basophils cause a massive release of histamine
Does a patient have to be previously exposed to an antigen in order to have an anaphylactoid reaction to it?
No
Patients who are predisposed to anaphylactoid reactions
- Pregnant
- Young
- Patients with atopy
What is often the first sign of an anaphylactic reaction under anesthesia?
Hypotension
Signs of anaphylaxis under anesthesia
- Hypotension w/ tachycardia
- Circulatory collapse
- Bronchospasm
- Flush
- Edema
- Cardiac arrest
Pulmonary signs of anaphylaxis
- Wheezing
- Bronchospasm
- Increased PIP
- Laryngeal edema/stridor
- Acute pulmonary edema
- Acute respiratory failure
- Hypoxia
Cutaneous signs of anaphylaxis
- Urticaria
- Flushing
- Periorbital and perioral edema
Treatment of anaphylactic reaction
- Stop administration
- 100% O2
- Positive pressure ventilation
- Discontinue volatile anesthetics
- Volume expanders (1-4L)
- Epinephrine
- Put patient’s head down
- Cardiac massage
- TEE
How does epinephrine treat an anaphylactic reaction?
- Increases cAMP which inhibits mediator release and increases Ca2+
- It’s a B2 agonist so it relaxes bronchial smooth muscle
- It’s an alpha agonist so it vasoconstricts vessels and increases SVR
Why might a patient not respond to catecholamines if they are in anaphylactic shock?
- On beta blockers
- Increased synthesis of nitric oxide
What drugs are helpful if your patient is resistant to epinephrine during an anaphylactic rxn?
- Norepi
- Glucagon
- Phenylephrine
Why does vasopressin treat anaphylactic rxns if epinephrine isn’t working?
- Causes a non-adrenergic vasoconstriction via V1 receptors
- Decreases nitric oxide
How long after the onset of anaphylactic shock should you wait to give vasopressin?
10-20min
What has been shown to treat anaphylaxis when epi and vasopressin aren’t working? Why?
Methylene blue because it interferes with nitric oxide
Dosage of diphenhydramine to treat anaphylaxis
1-2mg/kg
Dosage of hydrocortisone to treat anaphylaxis
2mg/kg
Why would Aminophylline be used to treat symptoms of anaphylaxis?
To treat resistant bronchospasm
What is indicated by an increase in plasma histamine after a suspected anaphylactic reaction
It indicates mast cell/basophil activation
What test can be used to determine immune vs. nonimmunologic anaphylactic reaction?
Tryptase
If a patient has both increased tryptase and histamine, what type of reaction did they have?
Immunologic anaphylaxis
If a patient has increased histamine but NO increase in tryptase, what type of reaction did they have?
Nonimmunologic anaphylaxis
What is the gold standard for detection of IgE-mediated reactions that identifies the culprit agent?
Intradermal skin testing
Common offenders of anaphylactic reactions
1) Sux/vec/atracurium
2) Latex
3) Antibiotics
4) Opioids
5) PABA ester local anesthetics
6) Hypnotics (propofol)
Is there cross-reactivity between non-depolarizing and depolarizing relaxants?
Yes
Is there cross-reactivity between cephalosporins and PCNs?
Yes
Is there cross-reactivity between ester and amide local anesthetics?
No
Populations at high risk for latex allergy
1) Spina bifida
2) Spinal cord injury
3) Healthcare workers
4) Allergies to bananas, avocados, kiwis
Risk factors for protamine allergy
- Seafood allergy
- Diabetics on NPH insulin
- Prior vasectomy