Transcript Perianesthetic Pharmacology

Perianesthetic Pharmacology
Drug Apps
2
 Epocrates
 http://www.epocrates.com
 Medscape
 http://www.medscape.com/public/mobileapp
 Drugs.com
 http://www.drugs.com/mobile.html
Anesthetic Agents
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 Inhalation agents (IAs)
 CNS is the target system.
 Depresses the reticular activating system, which
causes unconsciousness.
 Alters neuronal excitability throughout
the CNS.
General Effects of IAs
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
CNS
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

Cause unconsciousness through depression of excitable
tissue at all levels.
Decrease ICP through vasodilatation.
Hyperventilation counteracts this by causing hypocarbia
and vasoconstriction.
General Effects of IAs
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 Cardiovascular
 Depressant effect on the myocardium and vasculature.
  cardiac output, PVR, and SVR.
 Variable effect on the heart rate.
General Effects of IAs
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 Respiratory
 Bronchodilatation.
 Affects the ventilatory control.
 Dulls the response to a rising CO2.
 This effects continues into the postop period.
General Effects of IAs
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 GI – decreased motility.
 Mild to moderate relaxation of skeletal muscle.
 Temperature regulation
 Hypothalamic regulation is diminished.
 Body’s effector mechanisms (shivering, vascular control,
behavior choices) are inactivated.
Fluothane – halothane
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 Introduced in 1956.
 Sweet, non-irritating odor.
 Rapid onset.
 Slow arousal.
 High incidence of postop shivering.
 Sensitizes the myocardium to adrenergic agents 
ventricular ectopy, VT and V fib.
Fluothane – halothane
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 60-80% excreted unchanged by the lungs.
 Rest is metabolized by hepatic microsomal
enzymes.
 Halothane hepatitis – caused by a metabolite that
attaches to the liver and causes the body to not
recognize the liver as “self”.
 Is a trigger for malignant hyperthermia.
Forane - isoflurane
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 Has a pungent odor.
 Not used for induction, but for maintenance of
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anesthesia after induction with IV agents.
Excellent skeletal muscle relaxation.
Eliminated almost exclusively by the lungs.
Higher incidence of PONV.
Postop shivering may be increased due to intraop
vasodilation.
Suprane - desflurane
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 Newest inhalation anesthetic.
 Used for maintenance of anesthesia.
 Rapid onset and offset.
 Rapid offset leaves no lingering analgesia; must be
supplemented.
 Is an airway irritant.
 High incidence of breath-holding, apnea, coughing,
and increase in oral secretions.
 Not used in children, as it has a high incidence of
laryngospasm.
Ultane - sevoflurane
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
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Is non-irritating to the respiratory tract, and has a
pleasant smell.
Can be used for induction and maintenance of anesthesia.
Fast onset and offset, but not as fast as desflurane.
 Rapid offset leaves no lingering analgesia; must be
supplemented.
Does not sensitize the myocardium to adrenergic agents.
Fluoride metabolites – use with caution in renal
dysfunction.
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SevoFlo
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 Unlike many other inhalation anesthetics, which
have a pungent or irritating odor, SevoFlo smells
sweet, similar to fruit-flavored chewing gum. Your
pet . . . will fall asleep quickly and with minimal
stress. When the medical procedure is complete,
your pet will usually begin waking up within a few
minutes.
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Waste Anesthetic Gases in PACU
 Most inhalation agents and nitrous oxide are
excreted unchanged by the lungs.
 Prolonged exposure  reproductive and
neurologic problems, liver and kidney disease.
Diprivan - propofol
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 Is a sedative-hypnotic in a class by itself.
 Is a milky emulsion composed of eggs and soy.
 Effects:
 Rapid induction with frequent apnea.
 No analgesia.
 Rapid offset, with minimal PONV.
 Not a triggering agent for MH.
Diprivan - propofol
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 Less hangover
 Pts are responsive earlier
 Less PONV
 Pts more alert and can eat and drink earlier
 Less psychomotor impairment – earlier ambulation
Ketamine - Ketalar
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 Produces dissociative anesthesia.
 Feeling of dissociation from environment.
 Used for induction and maintenance of anesthesia.
 Intense analgesic properties.
 Almost half of pts over 30 yo exhibit delirium or
excitement on emergence.
 Can induce hallucinations.
Stages of Anesthesia
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Stage IV: Medullary depression


Overdose of anesthetic.
Stage III: Surgical anesthesia
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Cessation of spontaneous respirations
No reflexes.
Stages of Anesthesia
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 Classic reference points.
 Stage II: Stage of delirium
 Hallmark is involuntary activity.
 High risk of aspiration, laryngospasm, bronchospasm.
 Dysphoria, restlessness, muscle rigidity, urinary and
fecal incontinence,  BP and HR.
 Stage I: Stage of analgesia
 Can follow simple commands.
 Protective reflexes are intact.
Reflexes as a guide to depth of anesthesia
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 Reflexes come back in this order:
 lid or corneal reflex 
swallow  cough
 pupillary
Neuromuscular Junction
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Neuromuscular Junction
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 Nerve impulse causes release of acetylcholine (ACh)
into the synaptic cleft.
 ACh diffuses across the synaptic cleft, and binds on
the post-synaptic fibers of a muscle fiber.
 Results in a membrane depolarization, and a muscle
contraction.
Neuromuscular Junction
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 ACh is rapidly broken down by acetylcholinesterase
(AChE), which is stored on the muscle fiber.
 In addition, ACh is no longer released.
 The muscle contraction is terminated.
Depolarizing Muscle Relaxant
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 succinylcholine – Anectine – Quelicin - Sucostrin
 Is the only DMR in use in the US.
 Works in 1-1.5 min., and wears off in 4-8 min.
 A molecule of sux is 2 linked molecules of ACh.
 Works as an agonist; occupies the receptor and
stimulates it is exhausted.
Succinylcholine
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 Effects:
 Paralysis
and apnea.
 No effect on CNS.
 No analgesia.
 Fasiculations.
 Myalgias.
Succinylcholine
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 Effects:
 Hyperkalemia
in susceptible pts.
Can cause cardiac standstill due to
hyperkalemia.
 Is a triggering agent for MH.
 Avoid in children for this reason.
Succinylcholine
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 Is broken down by pseudocholinesterase, also
called plasma cholinesterase (PC).
 This enzyme can be under produced or absent; this
deficit is genetic, and runs in families.
 PC and serum albumin tend to be directly related.
 Sux in the absence of PC will result in paralysis
that lasts for several hrs to a day.
Non-Depolarizing Muscle Relaxants
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 NDMR occupy the cholinergic receptor
on the muscle fiber, resulting in
paralysis.
 ACh is still released, and competes for
the binding site.
Non-Depolarizing Muscle Relaxants
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 Paralysis occurs from fine to gross movement.
 As the pt recovers from the paralysis, it progresses
from gross to fine movement.
 Sequence of return:

Diaphragm  intercostal muscles  limbs & neck  hands 
jaw  eyes
Non-Depolarizing Muscle Relaxants
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 Effects of NDMR
 Paralysis with apnea.
 No effect on CNS.
 None of the effects seen with sux, i.e., fasciculations, myalgia,
hyperkalemia.
 No analgesia.
 Onset is variable, but averages several minutes.
Offset depends on the agent; can be 20-30 minutes
to 4-5 hours.
Curare
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
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Comes from an arrow poison used in the Amazon.
First discovered by the Europeans in the 16th
century.
First used in the US in the 1940s.
Causes histamine release.
Is cumulative, and can cause reparalysis, or
recurarization.
Not commonly used.
NonDepolarizing Muscle Relaxants
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 Tracrium – atracurium
 Intermediate acting
 Hoffman degradation
 Nimbex – cisatracurium
 Intermediate acting
 80% by Hoffman degradation
 Pavulon – pancuronium
 Long acting
 Histamine release
NonDepolarizing Muscle Relaxants
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 Zemuron – rocuronium
 Short acting
 Onset 1 min; offset 15-20 min
 No histamine release
 Norcuron – vecuronium
 Intermediate acting
 No histamine release
 No CV effects – useful in cardiac surgery
Awareness During Anesthesia
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 Incidence of 0.1-0.2%.
 Very frightening experience.
 One-half are reported in PACU.
 70% experience post traumatic stress syndrome:
sleep disturbances, nightmares, panic attacks,
flashbacks, avoidance of medical care.
Awareness During Anesthesia
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 Higher incidence during C-sections, cardiac
surgery and trauma.
 Lighter anesthesia is used due to limited cardiac
reserve, hypovolemia, hypotension, or fear of
decreasing the uterine tone and increasing blood
loss.
 Higher incidence with total IV anesthesia.
 Lower incidence with inhalation anesthetics.
BIS Monitor
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 Bispectral Index Monitor.
 Is an EEG-based monitor of anesthetic effect.
 Is used as an indicator of the level of sedation.
 Can greatly eliminate intra-operative recall.
 Used as an indicator to the depth of anesthesia.
Items for Further Review
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 Specific muscle relaxants
 How
they are metabolized
 How long they last
 Specific uses
Neuromuscular Junction
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NDMR Reversal Agents
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 Are anticholinesterase agents.
 Block the enzyme AChE, resulting in more Ach in the
neuromuscular junction.
 Results in reversal of the paralysis, and normal
muscle contraction.
NDMR Reversal Agents
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
Also cause:
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
Bradycardia,  CO.
Bronchoconstriction.
 GI peristalsis: urination, defecation.
To counteract these effects, must co-administer an
antimuscarinic agent.
 Atropine
 Robinul - glycopyrrolate

Effects of Antimuscarinics
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

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 HR.
Inhibit peristalsis and micturation.
Cause mydriasis.
Atropine crosses the blood brain barrier, and can
cause a central anticholinergic syndrome.
Robinul does not cross the BBB.
Anticholinergics
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 Neostigmine - prostigmine
 Enlon - edrophonium
 Enlon Plus – edrophonium and atropine
 Regonol - pyridostigmine
 To reverse a block, must have some recovery of
muscle function.
Inadequate Muscle Strength
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 Pt can be brought to PACU not fully reversed.
 Pt can be WNL on admission to PACU, and
reparalyze.
 It is rare, but could happen in OPS.
 Ask the pt to hold head up x 5 sec.
 Very frightening experience.
Malignant Hyperthermia
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 Rare, potentially fatal disorder of skeletal muscle
triggered by certain anesthetic agents.
 Before 1970, mortality was 70%.
 Dantrolene was introduced in 1979; now the
mortality is 6-7%.
Malignant Hyperthermia
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 MH is an autosomal dominant genetic trait, and runs
in families.
 Ask this question in anesthesia questionnaires.
 Incidence is 1:20000 to 1:50,000 in adults, and
1:15,000 in children.
 Many cases undetected
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Never anesthetized
Short anesthetic period
Triggering Agents
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 All inhalational anesthetics
 halothane
 isoflurane
 desflurane
 sevoflurane
 Succinylcholine
 NOT triggering agents:
 All muscle relaxants EXCEPT sux
 Propofol
 Nitrous oxide
Diagnosis
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 No lab test for MH.
 Must obtain a thumb-sized skeletal muscle biopsy
from the thigh that can only be done at 4 hospitals in
the US, and 1 in Canada.
 Cost is $6000 to $10,000.
 Muscle contracture testing.
 Genetic testing can be done at 2 hospitals in US.
Clinical Presentation
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 Triggering agent  release of abnormal amounts
of calcium from skeletal muscle.
 Results in sustained skeletal muscle contraction.
 Subsequently causes hypermetabolism, muscle
injury and muscle rigidity.
 Increased O2 consumption and CO2 production
precede hyperthermia.
Initial Signs and Symptoms
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 Increasing ETCO2
 Tachypnea and tachycardia
 Hypoxemia
 Muscle rigidity

Trismus – masseter muscle rigidity
Later Signs and Symptoms
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 Acidosis
 Oliguria
 Myoglobinuria; cola-colored urine
 Caused by rhabdomyolysis
 Ventricular irritability – V tach
 Hyperthermia
 Hypertension followed by hypotension
 Flushing, mottling of skin
Lab Values
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  CK
 Severe respiratory and metabolic acidosis.
 Altered coagulation indices.
  magnesium, calcium, potassium.
Prognosis
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 The combination of high temperature, acidosis,
hypoxemia and rhabdomyolysis can result in death.
 Recrudescence (reoccurrence) can occur in 25% of
cases.
Treatment
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 Follow the instructions on the MHAUS poster.
www.mhaus.org. 1.800.MH.HYPER.
 Dantrolene is the drug of choice. It is a muscle
relaxant that decreases the calcium release from
the skeletal muscle.
 All facilities that use IAs should have 36 vials of
dantrolene.
Dantrolene
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Initial dose is 2.5 mg/kg.
More than 10 mg/kg can be needed for treatment.
Should be fully effective in 5-10 min. after
administration.
Is not very soluble in water.
Mix with sterile water without bacteriostatic agents.
Revonto
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 Is a new preparation of Dantrolene.
 Enhanced reconstitution time of 20 seconds or until
the solution is clear.
 Use sterile water without a bacteriostatic agent.
Other Treatments
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 Hyperventilation with 100% O2
 Treat acidosis with bicarb.
 Avoid LR, as it can worsen the acidosis.
 Treat hyperkalemia with insulin and glucose.
 Use lidocaine to treat ventricular ectopy.
Other Treatments
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 Do not use calcium channel blockers. Can cause
severe hyperkalemia and myocardial depression.
 Active cooling of core, using several modalities.
Elective surgery for MH-susceptible pts
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 Avoid triggering agents.
 Can give propofol, opioids, NDMRs, local
anesthetics.
 Will use TIVA.
 Do not need to be pretreated with oral dantrolene;
can worsen pre-existing muscle disease.
MH Pts in an OPS
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 May be done in an out-patient setting.
 A minimum of 1 hr in PACU and 1.5 hrs in Phase II
are recommended.
Discharge after MH Symptoms
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 Masseter spasm
 Severe spasm requires overnight observation.
 Milder spasm requires 12 hrs observation; any additional
symptoms will require admission.
 Symptoms include: cola-colored urine,  temp,  pulse,
abnormal acid-base
Moderate Sedation
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 Midazolam approved in 1986.
 From 1986-88, there were over 80 midazolam-
related deaths.
 In 1991, a position statement on The Role of the RN
in the Management of Patients Receiving Conscious
Sedation was published.
Continuum of Sedation
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 Minimal sedation (anxiolysis): pt responds
appropriately to verbal commands.
 Moderate sedation
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Depressed LOC.
Pt responds to verbal commands; may be accompanied with
light tactile stimuli.
Can maintain own airway.
Protective reflexes are intact.
Continuum of Sedation
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 Deep sedation
 Pt may need assistance maintaining the airway.
 Spontaneous ventilation may be inadequate.
 Cannot easily be aroused.
 Respond purposefully after repeated or painful stimuli.
 Anesthesia
Criteria
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 Pre-sedation evaluation.
 Medications must be ordered by a qualified
physician who is credentialed to perform
conscious sedation at your facility.
 A qualified RN must administer the meds and
monitor the pt. Must have no other duties that
would leave the pt unattended, or compromise
the continuous monitoring of the pt.
Criteria
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 Need emergency equipment available.
 Need protocols for potential complications.
 Monitoring must include: BP, HR, ECG, SpO2,
resp. rate, and level of sedation.
 Vital signs must be taken every 5 minutes.
 Pt is discharged according to specific criteria.
Benzodiazepines
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Bind to specific receptor sites in the CNS, and
inhibit excitatory impulses.
 Effects:
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Anxiolysis
Sedation
Hypnosis
Anticonvulsant properties
Skeletal muscle relaxation
Valium - diazepam
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 Introduced in 1961.
 Is the ‘gold standard’ against which all other benzos
are compared.
 Duration is 3-4 hrs; active metabolite has a duration
of action of 21-37 hrs.
 Has a high incidence of venous irritation.
 Diazemuls.
Versed - midazolam
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 Is 3-4 times stronger than Valium.
 Duration of action is 60-90 minutes; has no
active metabolites.
Does not burn on injection.
Causes antegrade amnesia, but not retrograde
amnesia.
Dose is 0.5 – 2.5 mg to 5 mg.
Titrate to effect:
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
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somnolence, slurring of speech, nystagmus.
Romazicon - flumaxenil
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 Is a competitive benzodiazepine antagonist.
 Rapidly and effectively antagonizes the sedation.
 Is partially effective in reversing the respiratory
depression.
 Side effects: tachydysrhythmias, hypertension,
convulsions.
Romazicon - flumaxenil
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 Dose: 0.2 mg IV over 15 sec.
 May repeat in 1 minute intervals up to a maximum of
1.0 mg.
 Onset: 1-2 minutes.
 Duration: 45-90 minutes.
 Monitor the pt for resedation.
Diprivan
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 Is used in many settings, such as endoscopy or
cardiac cath labs.
 Routinely causes deep sedation.
 In Oklahoma, RNs may not administer anesthetic
agents.
 Diprivan is an anesthetic agent.
Analgesia
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 Pain is what the pt says it is.
 Need to use an objective pain tool or tools.
 Anticipate pain in almost all postsurgical pts.
Chronic Pain Pts
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 May be on many kinds of meds.
 Opioids.
 Tri-cyclic antidepressants are used for neuropathic
pain in the absence of depression.
 Anticonvulsants, such as Neurontin, Dilantin,
Tegretol, Depakote or Klonopin, are used to treat
peripheral nerve syndromes such as posttraumatic
neuralgia.
Tolerance vs. Addiction
75
 Tolerance
 Larger dose of opioid is needed to maintain the original effect.
 Physical dependence develops.
 Addiction
 Pattern of compulsive drug use.
 Continuing craving for an opioid.
 For effects other than pain relief.
Abstinence Syndrome
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 Anxiety, irritability.
 Chills alternating with hot flashes.
 Salivation, lacrimation, rhinorrhea.
 Diaphoresis, piloerection.
 Nausea/vomiting, abdominal cramps.
 Insomnia.
Morphine
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 Is the ‘gold standard’ against which all other opioids
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are measured.
Made from opium or poppy straw.
Affects the  (mu) receptors.
Expected effects are analgesia and constipation.
Onset: 1-5 minutes.
Peak: 20 minutes.
Duration: 4 hrs.
Morphine
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 Other effects:
 Drowsiness
 Mental clouding
 Respiratory depression which is enhanced by general
anesthetics, sedatives
  GI motility and nausea/vomiting
 Urinary retention
 Miosis
 Histamine release that causes hypotension.
 Altered thermoregulation  slightly lower body
temperature
Sublimaze - fentanyl
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 Is 80-100 times stronger than morphine.
 Is a synthetic meperidine derivative.
 Most commonly abused drug in the perioperative
arena.
 Onset is 30-60 seconds; duration of action is 3060 minutes.
 Respiratory depression can outlast analgesia.
 Can cause muscle rigidity with high doses.
 No histamine release.
Demerol - meperidine
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 Produces a metabolite called normeperidine.
 Is a CNS excitotoxin that causes anxiety, tremors,
muscle twitches, and seizures.
 These effects are not seen for 2-3 days; will not
occur immediately after surgery.
 Should not be used for more than 48 hrs for acute
pain, and should not be used for chronic pain.
Demerol - meperidine
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 Is metabolized in the liver. In pts with cirrhosis, the
half-lives of both meperidine and normeperidine are
prolonged by up to 80%.
 Demerol 75-100 mg is equivalent to MS 10 mg.
 Usual dose of Demerol is 50 mg.
 Demerol is frequently under dosed.
Demerol
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 Is useful for postoperative shivering, esp. in the
absence of hypothermia.
 Dose is 12.5-25 mg.
 Is thought to act through a K receptor mechanism.
Dilaudid - hydromorphone
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 5-10 times more potent than morphine.
 Less sedating than morphine.
 No histamine release.
 Less nausea and vomiting.
 More potent analgesia.
Dilaudid - hydromorphone
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 Dose is 0.2mg (equianalgesic to 1 mg of morphine).
 Onset 1 min.
 Peak 5-20 minutes.
 Duration of action 2-4 hrs.
Intramuscular Injections
85
 Not recommended.
 Pain from injection itself.
 Erratic analgesia due to varied absorption.
 Useful occasionally in outpatient settings.
Narcan - naloxone
86
 Is an opioid antagonist that works at the mu
receptor.
 Reversal of respiratory depression is seen in 1-2
minutes, and lasts for 60 minutes.
 Dose: mix 0.4 mg of Narcan in 9 ml NSS. Results
in a concentration of 0.04 mg/ml.
 Give 1 ml or 0.04mg at a time until desired results
are achieved.
Negative Pressure Pulmonary Edema
87
 Is caused by generating negative intrapleural
pressures against an obstructed airway.
 Creates an elevated hydrostatic pressure that
forces fluid out of the vasculature and into the
lungs.
 Accompanying hypoxia causes vasoconstriction
and an increased venous return.
 Negative intrathoracic pressures decrease the
ejection fraction of the heart.
 All result in pulmonary edema.
Negative Pressure Pulmonary Edema
88
 Also seen after laryngospasm or croup.
 There is no intrinsic defect in the myocardium.
 Signs and symptoms:
 Frothy sputum
 Hypoxemia
 Tachypnea
 SOB
 Rales
 CXR that shows diffuse infiltrates.
Negative Pressure Pulmonary Edema
89
 Treat with:
 Diuretics.
 Supplemental oxygen.
 Intubation and PEEP if necessary.
 Morphine, Versed.
 Usually resolves quickly – within 24 hours.
Oral Analgesics
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 Mainstay of outpatient pain management.
 Useful for longer pain control.
Oral Analgesics
91
 Hydrocodone



Mod. to severe pain
1-2 tabs q4-6 hrs
Max 8 tabs/day
 Oxycodone




Mod. to severe pain
1-2 tabs q4-6 hrs
Max 8 tabs/day
Better analgesia than
hydrocodone
Hydrocodone
92
 Lortab –500 mg acetaminophen.
 Lorcet 10/650 – 10 mg hydrocodone and 650 mg
acetaminophen.
 Vicodin – 5 mg hydrocodone and 500 mg
acetaminophen.
 Vicodin ES – 7.5 mg hydrocodone and 750 mg
acetaminophen.
Oxycodone
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 Percocet 5/325 - 5 mg oxyocodone and 325 mg
acetaminophen.
 Percocet 7.5/500 – 7.5 mg oxyocodone and 500 mg
acetaminophen.
 Percocet 10/650 - 10 mg oxyocodone and 650 mg
acetaminophen.
 Percodan – 5 mg oxyocodone and 325 mg aspirin.
Acetaminophen
94
 3 gms a day is max dose.
 This maximum is new as of July 2011.
 Can cause liver damage, especially with impaired
liver function.
 Is the leading cause of liver failure.
 8 Lortabs a day are max.
 Percocet 10/650 – 6 pills a day are max.
Analgesia Prior to Discharge
95
 Give pt oral analgesic.
 IV meds will wear off before the pt gets the
prescription filled.
 Pt will frequently be unable to get pain under control
without this sequence.
Chronic Pain Control
96
 Meds don’t contain acetaminophen due to potential
for liver toxicity.
 Have an immediate release med and a time-release
med, i.e. OxyIR and Oxycontin, MSIR and MsContin.
 Have pt take their time-release med the morning of
surgery.
Items for Further Review
97
 Theories of pain – transmission, receptors,
modalities of pain control.
 Onset, duration of action, and specific side effects of
analgesics.
NSAIDs
98
 Can be given preoperatively as well as
postoperatively.
 Their anti-inflammatory effects are a logical choice
for the inflammation that accompanies surgery.
 Diminish or prevent central as well as peripheral
sensitization.
 No sedation; no impairment of GI motility.
Toradol - ketorolac
99
 Can be given parenterally.
 Effective in relieving moderately severe pain, esp.
when given in conjunction with opioids.
 Can only be given for 5 days, due to increased risk
of GI bleeding.
 Lower dose with renal impairment.
 Contraindicated in pts with prior hx of allergic
reactions to ASA or other NSAIDS, GI bleeding or
peptic ulcer disease.
Ofirmev - acetaminophen
100
 Can be given IV
 Approved in pts 2 y/o and older
 Indicated for:
 Mild to moderate pain.
 Moderate to severe pain in conjunction with opioids
 Reduction of fever
 Do not exceed maximum recommended daily dose of
acetaminophen.
 Cost: $10.75/vial.
Lidocaine
101
 Medium-acting, quick, potent.
 High incidence of sleepiness and dizziness.
 Duration 30-120 minutes.
 Depresses laryngeal and tracheal reflexes.
 Also available in Lidoderm patches.
Bupivicaine
102
 Trade names: Marcaine, Sensorcaine.
 High potency, long duration of action of 3-10 hrs.
 Prolonged anesthetic and analgesic action.
Ropivicaine
103
 Trade name: Naropin.
 High potency, similar to bupivicaine.
 Produces less motor blockade than bupivicaine.
Local Anesthetics
104
 Does help with postop pain.
 Can result in systemic absorption.
 Infusion pumps of local anesthetic into incision.
Systemic Absorption of Local Anesthetics
105
 CS stimulation followed by CNS depression.
 Restlessness, muscle twitching, tremor, lightheadedness,
tinnitus, circumoral tingling progressing to seizures.
 CNS stimulation phase may be skipped entirely and
progress straight to CNS depression.
 Lethargy may be the only symptom.
 CV: Decreased myocardial electrical activity,
conductivity, and force of conduction.
Treatment of Systemic Absorption
106
 Administer oxygen.
 Be prepared to administer a benzodiazepine for
seizure activity.
 Monitor HR and ECG carefully.
Scalene Block
107
 Infiltration of a local anesthetic into the brachial
plexus using a nerve stimulator to ascertain correct
placement.
 Provides analgesia after shoulder surgery for 12-36
hours.
 Should be done preop not postop.
Scalene Block
108
 Side effects:
 Droopy or reddened eye or eyelid.
 Dysphagia.
 Raspy cough.
 Hoarse voice.
 Diaphragmatic hemi paralysis resulting in hypoventilation,
hypoxia, and dyspnea.
 Contraindicated in pts with impaired pulmonary status.
Scalene Block
109
 Adverse effects:
 Pneumothorax.
 Permanent nerve injury. Paresthesia lasting more than 1 week.
 Systemic toxic reactions to the local anesthetic.
Femoral Block
110
 Infiltration of a local anesthetic into the sciatic and
femoral nerve plexus using a nerve stimulator to
correctly place the needle.
 Provides analgesia for 12-36 hours after knee
surgery – ACLs, lateral release.
 Side effects:
Inability bear weight on affected leg.
 Urinary retention.
 Delayed diagnosis of compartment syndrome.

Bier Block
111
 Exsanguination of the surgical arm with an
Esmarch bandage.
 Application of a tourniquet, then infusion of a local
anesthetic through a previously placed saline lock.
 Provides regional anesthesia during the surgery.
 Pt will require additional analgesia
postoperatively.
 Monitor for systemic effects of the local anesthetic.
Epidural and Intrathecal Analgesia
112
 Epidural: drug in injected outside the dura mater,
and must cross the blood brain barrier.
 Intrathecal: drug is injected through the dura
mater into the CNS. Smaller doses of drugs are
used.
 Provides potent analgesia without the systemic
side effects of parenteral opioids.
 Must use preservative-free meds.
Epidural and Intrathecal Analgesia
113
 Intrathecal: dose is 0.2 – 1.0 mg MS. Duration of
analgesia is 8-16 hrs.
 Epidural:
Morphine – onset of action is 45-60 minutes. Duration
of action is 12-24 hrs. Rostral spread of morphine can be
a problem.
 Fentanyl – onset of action is 5-10 minutes. Duration of
action is 5-6 hrs. Less chance of rostral spread due to
chemical structure o the drug.

Pain Control
114
 Be cautious with parenteral opioids.
 In PACU, will probably need to give opioids until
epidural begins working.
 Parenteral opioids will augment the potential for
respiratory depression caused by epidural.
Side Effects
115
 Delayed respiratory depression – due to rostral
spread of morphine; not really a factor with fentanyl.
 Pruritis - treat with antihistamines, low-dose
Narcan.
 Nausea/vomiting – treat with anti-emetics.
Side Effects
116
 Urinary retention – assess frequently for bladder
distention. May require a catheter.
 Hypotension – due to sympathetic blockade. Treat
with fluids.
 Systemic local anesthetic toxicity (if local anesthetic
is used).
 Epidural hematoma.
Spinal Anesthesia
117
 Injection of local anesthetic through the dura mater,
into the CNS.
 Provides anesthesia to the lower half of the body.
 Local anesthetic can spread upward from the
injection site; is controlled by pt position and
addition of dextrose.
Spinal Anesthesia
118
Spinal Anesthesia
119
 Ventilatory inadequacy:
 Pt may feel dyspneic due to inability to feel intercostals.
 Numbness of hands.
 Hypotension.
 Apnea.
 Sympathetic blockade is 3-6 dermatomes higher
than the sensory block.
Spinal Anesthesia
120
 Sympathetic blockade results in hypotension due to
vasodilatation.
 Treat with:



Hydration.
Put the foot of the bed up to increase venous return.
Ephedrine 5-10 mg IV.
Side Effects
121
 Bradycardia progressing to asystole.
 Urinary retention.
 Loss of temperature regulation below level of spinal.
 Postdural headache.
Spinal Anesthesia
122
 Reappearance of neurologic functions:
 Deep pressure  motor function  proprioception  cold and
warmth  pain  autonomic functions.
 Autonomic functions include:
 Vasomotor.
 Bladder control.
Discharge Criteria after Spinal Anesthesia
123
 Normal perianal pinprick sensation.
 Plantar flexion of the foot; normal proprioception of
the big toe.
 No residual motor block.
 Absence of orthostatic hypotension.


BP in sitting and supine positions.
Less than 10% drop between BPs.
PCA Pumps
124
 Need a basal infusion as well as the intermittent
infusion.
 Initiate prior to leaving PACU.
 Need additional analgesia to obtain adequate pain
control in PACU.
Postoperative Nausea and Vomiting
125
 Implications of PONV:
 Is often feared by pts more than surgical pain.
 Incidence of the literature ranges from 20-30%. The
incidence among high risk pts can be as high as 70-80%.
 Raises institutional costs due to the cost of the
antiemetics and increased nursing time.
 Each incidence of vomiting delays discharge from PACU
by an average of 20 minutes.
 Can lead to an increased LOS.
Factors That Increase the Risk of PONV
126
 Age.
 Children
 Decreases after 70 y/o.
 Female gender.
 History of previous PONV.
 History of motion sickness.
 Delayed gastric emptying.
 Pregnancy
 Obesity
 Diabetes
Factors That Increase the Risk of PONV
127
 Type of surgery:
 ENT
 ophthalmic
 Plastic and reconstructive
 Gynecologic and breast
 Laparoscopy and abdominal
 Increasing duration of surgery increases the risk of
PONV.
 Use of opioids, nitrous oxide, reversal agents.
Factors That Decrease the Risk of PONV
128
 Smokers have a lower incidence of PONV.
 Propofol, TIVA.
 Regional anesthesia.
Physiology of PONV
129
 NV is a complex process regulated by the emetic
center in the medulla.
 This center receives input from:


Chemoreceptor trigger zone.
From the brainstem, cortex, and certain organs, such as the
heart, testes, gastrointestinal tract.
Chemoreceptor Trigger Zone
130
 Serotonin; sometimes called 5-HT3 receptors.
 Dopamine.
 Histamine.
 Cholinergic.
Antiemetic Drugs
131
 Serotonin antagonists – appear to be the most
efficacious of the antiemetics.



Zofran – ondansetron
Kytril - granisetron
Anzemet – dolasetron
 Zofran
 Appears to have better antivomiting effect than
antinausea effect.
 No value of additional dose if maximum dose of 4 mg
has been given within 24 hours.
Dopamine Blockers
132
 Reglan – metaclopramide.
 Enhance gastric emptying.
 Most common dose of 10 mg IV not effective for prophylaxis.
 Can cause extrapyramidal reactions.
 Phenothiazines:
 Compazine – chlorpromazine.
 Phenergan – promethazine.
 Extravasation risk.
 Can cause extrapyramidal reactions.
Dopamine Blockers
133
 Inapsine – droperidol.
 FDA black box warning in 2001.
 ECG monitoring for 2-3 hrs after dose.
 Can cause extrapyramidal reactions.
 Scopolamine
 Transdermal patch should be applied 4 hrs before the end of
surgery, of preop for short surgeries.
 Dose is delivered for 3 days if left on.
 Side effects: dry mouth, dizziness, dilated pupils, urinary
retention, drowsiness.
Prophylaxis of Pts at High Risk for PONV
134
 Several kinds of antiemetics are given.
 Dexamethasone 4-8 mg; give at least 2 hours before




the end of surgery.
Serotonin antagonist – Zofran, Anzemet.
An phenothiazine – Phenergan.
An anticholinergic – Scop patch.
Hydrate the pt.
Prophylaxis of Pts at High Risk for PONV
135
 Use propofol; avoid nitrous oxide and IAs.
 Minimize use of postop opioids by using regional
anesthesia.
 Relief Band – provides acustimulation.
Treatment of PONV
136
 Give a 5HT3 blocker if not already given. Don’t give




if one was already given.
Treat with a drug from a different class.
Hydrate.
Propofol 20 mg – sub hypnotic dose.
Ginger ale.
Items for Further Review
137
 Nitrous oxide.
 Acid-base and interpretation of ABGs.
 Induction agents.