Dr. CATHERINE GALLANT Department of Anesthesiology University
of Ottawa General Campus
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OUTLINE Definition Indications for use Contraindications
Pharmacology Complications
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DEFINITION A technique to provide an altered state of
consciousness by administration of medications that permits a
patient to undergo painful procedures but still respond to verbal
commands while maintaining an unassisted airway
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INDICATIONS Used to facilitate many diagnostic and therapeutic
procedures May be used intra-operatively May be performed in a
location remote from the operating room Ever increasing demand
fuelled by patients Limited capacity for anesthesiologists to
provide these services
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APPLICATIONS Primarily day surgeries Lack of dependence on
hospital beds More flexibility in scheduling Shorter waiting lists
Improved efficiencies Low morbidity and mortality Low rates of
complications Lower costs Less special investigations required
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APPLICATIONS Dental Dermatology Gynecology General surgery
Ophthalmology Orthopedics Pain Clinic Plastic surgery Urology
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DEFINITIONS Analgesia - Relief of pain without intentionally
producing a sedated state. Altered mental status may occur as a
secondary effect of medications administered for analgesia.
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DEFINITIONS Minimal sedation drug induced state where the
patient responds normally to verbal commands. Cognitive function
and coordination may be impaired but ventilatory and cardiovascular
function are unaffected. Anxiolysis alternate term
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DEFINITIONS Moderate sedation and analgesia a drug induced
depression of consciousness where the patient responds purposefully
to verbal commands alone or when accompanied by light touch.
Protective airway reflexes and adequate ventilation are maintained
without intervention. Cardiovascular function remains stable.
Conscious sedation
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DEFINITIONS Deep sedation and analgesia - A drug induced
depression of consciousness where the patient cannot be easily
aroused but responds purposefully to noxious stimulation.
Assistance may be needed to ensure the airway is protected and
adequate ventilation maintained. Cardiovascular function is usually
stable.
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DEFINITIONS General anesthesia a drug induced loss of
consciousness, during which the patient cannot be aroused, even
with painful stimuli, and often requires assistance to protect the
airway and maintain ventilation. Cardiovascular function may be
impaired.
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EUROPEAN UNION OF MEDICAL SPECIALISTS Level 1 Fully awake Level
2 Drowsy Level 3 Rousable by normal speech
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OBJECTIVES To achieve sedation level 2 and 3 (minimal to
moderate sedation) which allows patients to undergo and tolerate
unpleasant procedures To avoid deeper levels of sedation and the
related complications This cannot be completely avoided! Continuum
which is difficult to divide into discrete stages Always maintain
verbal contact
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BENEFITS Appropriate sedation/analgesia will allow the patient
to tolerate unpleasant procedures by relieving anxiety, discomfort
or pain In the uncooperative patient, sedation/analgesia may
facilitate those procedures which are not uncomfortable but which
require that the patient not move
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QUALIFIED INDIVIDUALS Competency based education, training and
experience in: Patient evaluation Performance of sedation Knowledge
of pharmacology of drugs used Rescuing the patient from
complications of deeper levels of sedation Airway compromise
Inadequate ventilation Cardiovascular instability
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PATIENT EVALUATION Screening for medical risk factors How will
these alter response to sedation? Abnormalities of major organ
systems? Previous adverse reactions with sedation/analgesia as well
as regional and general anesthesia? Allergies to drugs? Medications
drug interactions? History of drug and alcohol abuse? NPO
status
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PATIENT EVALUATION Abnormalities of major organ systems Cardiac
Respiratory Renal Hepatic
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PATIENT EVALUATION Previous adverse reactions with
sedation/analgesia as well as regional and general anesthesia
Details Where it happened
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PATIENT EVALUATION Allergies to drugs? What is the reaction?
When did it occur? Family history?
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PATIENT EVALUATION History of drug and alcohol abuse? May
indicate tolerance Cross tolerance between classes of drugs
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PATIENT EVALUATION Review medications possible drug
interactions? MAOIs such as phenelzine (Nardil), tranylcypromine
(Nardil), moclobemide
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PATIENT SELECTION Focused physical exam Evaluation of airway
Auscultation of heart and lungs Assessment vital signs Review labs
Consider consult prn
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PATIENT SELECTION Airway issues that may present concerns
History Previous problems with anesthesia or sedation Snoring,
stridor or sleep apnea Advanced rheumatoid arthritis Chromosomal
abnormalities e.g. trisomy 21 Physical examination Obesity
especially involving neck and facial structures
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PATIENT SELECTION Airway issues that may present concerns
Physical examination Short neck, limited neck extension, decreased
TMD of < 3 cm in adult, neck mass, c-spine disease or trauma,
tracheal deviation, dysmorphic features Small mouth opening (< 3
cm in adult), protruding incisors, loose or capped teeth, dental
appliances, high arched palate, macroglossia, tonsillar hypertrophy
Micrognathia, retrognathia, trismus, significant malocclusion
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DIFFICULT AIRWAY
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PATIENT SELECTION Who is a candidate for sedation? ASA 1 and
ASA 2 ASA 3 in stable condition Must be compatible with the
procedure Must be capable of giving informed consent
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PATIENT SELECTION Who is at increased risk of complications?
Extremes of age Multiple co-morbidities Severe systemic disease
Drug and/or alcohol abuse Uncooperative patient Morbidly obese
patient Potential difficult airway Obstructive sleep apnea
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ADVANCED AGE Higher risk of adverse events Increased
sensitivity to sedative drugs Medication interactions Higher peak
serum levels of medications
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MULTIPLE CO-MORBITIES ing ASA status correlates with ing risk
of adverse events (ASA III or >) Any co-morbidity that increases
risk of cardio- respiratory depression with sedatives is
significant CHF, neuromuscular disease COPD, dehydration
Anemia
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PATIENT SELECTION Who is not a candidate? Language barrier
History of problems with previous anesthesia Known or suspected
difficult ventilation or difficult intubation No person to
accompany them home
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PREPARATION Do you have informed consent? Is patient aware of
risks and the limitations? Have they been given alternative choices
to procedure? Have questions been answered? What is the NPO status?
Risks versus benefits Machine and drug check? Drugs and antagonists
Emergency equipment available and checked? Defibrillator and skills
of use
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ASPIRATION RISK Fasting pre-procedure decreases risks during
moderate sedation and strongly decreases risks during deep sedation
ASA guidelines recommend if procedure is elective fasting
guidelines should be as for GA If not met then consider delaying
procedure, reducing sedation level or ETT If emergency then may
have to reconsider approach
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SUMMARY OF ASA PRE- PROCEDURE FASTING GUIDELINES INGESTED
MATERIALMINIMUM FASTING PERIOD Clear liquids2 hours Breast milk4
hours Infant formula6 hours Nonhuman milk6 hours Light meal6
hours
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EQUIPMENT Dedicated qualified personnel Must be uninterrupted
and continuous presence IV access Airway adjuncts Bag valve mask,
oral and nasal airways, equipment for endotracheal intubation
Suction for secretions
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MONITORING Does monitoring level of consciousness decrease
risks of complications when administering procedural sedation?
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MONITORING Maintain verbal contact with patient Blood pressure,
heart rate, respiratory rate measured at regular intervals Oxygen
saturation, cardiac rhythm and ETCO2 should be monitored
continuously
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MONITORING Monitor patients response to medication and
procedure Level of alertness, depth of respiration and response to
painful stimuli all determine subsequent dosing
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MONITORING Supplemental oxygen often recommended to maintain
oxygen reserves and prevent hypoxemia May delay recognition of
hypoventilation ETCO2 monitoring useful Brief episodes hypoxemia
and hypoventilation may occur clinical significance?
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TECHNIQUES Technique will vary from patient to patient Dosing
of analgesics and anxiolytics vary widely Dosing depends on
procedure as well as the anxiety of the patient Comfort measures
contribute to reducing anxiety and pain
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TECHNIQUES Anxiety may be reduced by other methods than
pharmacological Preoperative explanation of the procedure Calm and
reassuring manner Quiet atmosphere with appropriate music
Comfortable room temperature or warm blankets
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AGENTS USED Ideal drug has rapid onset of action and short
duration of action, will maintain hemodynamic stability and have no
side effects No single drug available with all of these
features
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AGENTS USED Anxiolytics Benzodiazepines Diazepam, midazolam,
lorazepam Benzene ring fused to diazepine ring All highly
lipophilic Highly protein bound All absorbable after po
administration
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MIDAZOLAM Midazolam most commonly used Rapidly enters CNS then
redistributed Works through GABA pathways Distribution of GABA
receptors restricted to CNS Minimal effects outside of CNS Most
important clinical effects Sedative-hypnotic Amnestic Anxiolysis
Anti-convulsant No analgesia
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MIDAZOLAM Favorable side effect profile Minimal depression of
ventilation May cause mild BP esp in hypovolemic patient
Synergistic with narcotics Combo may cause severe respiratory
depression Antagonist available: Flumazenil Dosage 10 to 25 cg/kg q
3 to 5 minutes
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AGENTS USED Propofol Phenol derivative, highly lipophilic Can
be painful on injection Rapidly metabolized in liver with high
plasma clearance Onset within 40 seconds with duration 8 - 10
minutes Causes peripheral vasodilatation BP more pronounced with
age, intravascular volume or with rapid injection
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PROPOFOL Potent respiratory depressant with doses MV through TV
and RR Has anti-emetic effects Sedative and amnestic not analgesic
No reversal agent Difficult to titrate in some cases, can cause
very deep sedation
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PROPOFOL Dosage unchanged if renal or liver impairment
Metabolism appears to be slower in elderly Reduce doses by 20% and
increase dosing interval 100 to 500 cg/kg every 3 to 5 minutes
bolus Continuous infusion 25 to 100 cg/kg/min May require addition
of short acting opioids due to absence of analgesic activity. This
increases risk of respiratory complications
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KETAMINE Highly lipid soluble derivative phencyclidine Rapid
onset of action Use limited by side effects Dreams,
halllucinations, out of body experiences Significant cardiovascular
effects Sympathomimetic BP, HR, CO Minimal respiratory depression
Bronchodilatation
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KETAMINE Profound analgesia Multiple routes of administration
May supplement inadequate regional anesthesia 50 to 100 mcg/kg
usual single dose No more than 10 mg/hour to avoid side
effects
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PENTOTHAL IV barbiturate, induction agent Hypnotic, sedatives,
anticonvulsants Undergoes hepatic metabolism Recovery after bolus
comparable to propofol because of redistribution to inactive tissue
sites Even single boluses can lead to psychomotor impairment for
several hours
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PENTOTHAL CNS depressant Anti-analgesic properties May reduce
pain threshold BP due to peripheral vasodilation Transient as
compensatory HR Respiratory depressant TV and RR transient
apnea
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ETOMIDATE IV anesthetic with minimal hemodynamic effects
Hypnotic but no analgesic properties Rapid onset of anesthesia
almost immediate - with minimal changes in HR and CO Usual dosing
0.1 to 0.15 mg/kg IV for PSA Causes adrenocortical suppression so
not widely used Myoclonus also seen frequently
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AGENTS USED Miscellaneous agents Chloral hydrate Pentobarbital
Methohexital Dexmedetomidine Local anesthetics May reduce doses of
sedatives and narcotics Useful as co-analgesics
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OPIOIDS High degree of variability in dose response
Inter-individual variation Analgesia, euphoria, sedation,
concentration Clearance primarily hepatic metabolism May be active
metabolites
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SIDE EFFECTS Cardiovascular May produce orthostatic hypotension
Respiratory Dose dependent depression of ventilation Decreased
responsiveness to CO2 May persist for several hours Apnea CNS Do
not reliably produce unconsciousness Skeletal muscle rigidity
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SIDE EFFECTS Sedation Nausea and vomiting Direct stimulation
CRTZ dopamine receptors Biliary tract Spasm of biliary smooth
muscle May be confused with angina
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AGENTS USED Fentanyl Synthetic opioid structurally related to
meperidine (phenylpiperidine derivative) 75 to 125 times more
potent than morphine More lipid soluble than morphine crosses BBB
Short acting with rapid redistribution to tissue Clinically rapid
onset (2 to 3 minutes) No amnestic properties
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FENTANYL Primary side effect is respiratory depression Will
potentiate sedative effects of other drugs Wide range of doses 0.25
to 0.5 cg/kg q 3 to 5 minutes 1 to 2 cg/kg for analgesia With
multiple bolus doses or continuous infusion the duration of action
is prolonged
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ALFENTANIL 1/5 to 1/10 th potency fentanyl More rapid onset and
shorter duration 1.4 minutes May be useful for retrobulbar blocks
10 fold inter-individual variation in dosing 0.1 to 0.4 cg/kg/min
by infusion
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REMIFENTANIL Unique because of ester linkage and metabolism by
plasma esterases Short acting, titratable, rapid onset and offset,
rapid recovery after infusion Boluses excellent for short painful
procedures Doses 0.25 to 1 cg/kg Infusions for sedation Doses 0.05
to 0.2 cg/kg/min
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TECHNIQUES May be by intermittent bolus or by continuous
infusion Target controlled infusions Plasma levels Effect site
levels
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TECHNIQUE Monotherapy may be desirable Short acting drugs may
be desirable Onset of action Small increments If synergistic action
reduce to usual dose Antagonists readily available
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TECHNIQUE Sedation and inadequate block Surgeon may have to
supplement if block is inadequate Duration of surgery may exceed
duration of local anesthetic Restlessness and hypoxia Consider in
differential diagnosis
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TIPS If elderly or co-morbid disease then may be more
conservative with approach Start with lower dose Administer meds
more slowly Be aware of slower circulation times Redose at less
frequent intervals
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TIPS NEVER BE AFRAID TO CALL FOR HELP
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COMPLICATIONS Serious complications rare All sedatives and
narcotics will cause adverse reactions in some patients even within
recommended doses Extremes of age most at risk Most sedatives cause
dose dependent respiratory depression Risk of desaturation up to
11% with propofol, even with supplemental oxygen Hypoventilation
and apnea usually easily treated
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COMPLICATIONS Treat respiratory complications with patient
stimulation, oxygen, airway positioning or brief ventilatory
support Cardiovascular instability uncommon More likely to occur if
significant cardiac morbidity Hypotension and bradycardia may
develop in patients on CV depressants Usually transient
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COMPLICATIONS Vomiting Seen in approximately 5% PSA More common
if narcotics given Little evidence regarding prophylaxis Inadequate
sedation preventing completion of procedure Over sedation Agitation
Allergic reactions
RECORDS Vital signs and level of consciousness Document at
baseline Regular, frequent intervals during the procedure Regular,
frequent intervals during recovery Prior to discharge
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RECOVERY PERIOD Requires monitoring as during procedure
Patients may be at increased risk after removal of painful stimulus
What is ideal length of recovery period? Various criteria available
such as Aldrete ConsciousnessActivity RespirationSaturation
Circulation Consider pain and nausea
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DISCHARGE CRITERIA Fully conscious Respond appropriately Walk
unassisted Baseline vital signs Pain, nausea and vomiting, bleeding
all under control Must have accompanying responsible person
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AFTERCARE Responsible accompanying person for 24 hours Written
detailed instructions for dealing with complications Medical
assistance readily available Should be contacted next day by phone
No major life decisions, driving or alcohol for 24 hours
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REFERENCES Practice Guidelines for Sedation and Analgesia by
Non-Anesthesiologists - ASA Basics of Anesthesia 5 th edition -
Stoelting
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CLINICAL SCENARIOS You are asked to provide sedation for
cataract surgery to an 80 year old male. He has a history of
controlled hypertension. NKDA. Medications: Atenolol 50 mg bid Any
concerns? What would you choose for sedation for this patient?
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The procedure finishes and you bring the patient back to the
PACU in stable condition. 15 minutes later you receive a call that
your patient is no longer responsive What is your differential
diagnosis? How do you approach the management?
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You are monitoring a 62 year old patient under spinal
anesthesia for a total knee replacement when she suddenly becomes
bradycardic - HR drops to 45 (from 70) What are your first steps?
What treatment would you give if any?
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You are in the endoscopy suite providing sedation for
colonoscopy. Your patient is a 50 year old for routine screening
with no significant past medical history. 10 minutes into the
procedure BP drops to 100/60 from baseline 135/72 Any
concerns?
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You are monitoring a 73 yo male under SAB who is undergoing
TURP. One hour into the procedure he is becoming increasingly
restless. You give 1 mg midazolam IV. He becomes more confused and
pulls out his IV Differential??