1. Managing “Anesthesia” in Radiology
Local anesthesia to conscious sedation
Collan Simmons, B.Sc., M.D.
PGY-5 Anesthesia
(Anisa’s husband)

2. Warm Up Questions What are you typical doses of
Fentanyl?
Midazolam?
What is the name of the antidote for benzodiazepines?
Maximum dose of lidocaine (/kg)? With Epi?

3. Objectives Basics of Sedations Local Anesthesia Monitors & Support
Opioids
Benzodiazepines
Local Anesthesia
Toxicities & Management

4. What you need before you start
Sedation
What you need before you start

5. Monitors Required: Suggested Oxygen Saturation/HR Blood pressure ECG
Tells you about oxygenation (not ventilation)
Blood pressure
Suggested
ECG
Respiratory Rate

6. Sedation Basics IV access Oxygen Backup Equipment
Nasal prongs (Fi02 = 30% max)
Face mask (Fi02 = 50% max)
Backup Equipment
IV fluids
Self-inflating resuscitation bag
Oral/Nasal Airways
Antidotes

7. Fasting Guidelines: Any procedure that may require IV sedation:
8 hours after a meal that includes meat, fried or fatty foods
6 hours after a light meal (such as toast and a clear fluid), or after ingestion of infant formula or nonhuman milk
4 hours after ingestion of breast milk
2 hours after clear fluids.

8. Sedative Agents

9. Sedation Goals Analgesia Anxiolysis +/-Amnesia
Intra-procedural vs long acting
Anxiolysis
+/-Amnesia
Return to baseline shortly after procedure

10. Ideal Properties of Sedative Agents
Titratable
Fast Onset
Short duration
Wide therapeutic index
Minimal Side effects
Antidote/Reversal Agent available

11. Sedation
Typical Agents Used
Opioids
Benzodiazepines
Propofol

12. Propofol Titratable Amnesia Sedation No analgesia Fast Onset
Short duration
Amnesia
Sedation
No analgesia

13. } Propofol NARROW Therapeutic index Hemodynamics: Sedation Apnea
Loss of airway reflexes
Loss of consciousness
Hemodynamics:
Direct myocardial depressant
Vasodilator }

14. = Best left to Anesthesia
Propofol
Prior to use
Ready for general anesthesia
A/W control
Possible ventilation
Ready for hemodynamic consequences
Fluids
Short acting vasoactive agents
= Best left to Anesthesia

15. Opioids

16. Opioids
Common Drugs
Fentanyl
Morphine
Hydromorphone

17. Opioids Good Characteristics Bad Characteristics Analgesia
Respiratory depression
Pruritus
Nausea

18. Fentanyl Synthetic opioid 100X more potent than morphine Fast onset
Highly lipid soluble
Minimal pruritus, nausea
100X more potent than morphine
Fast onset
No active metabolites
Clinically effective for approximately 30 min
dose dependent

19. Fentanyl Supplied as: Dosing: (by ideal weight) Onset
50 mcg/ml (equivalent in potency to 5 mg morphine)‏
Dosing: (by ideal weight)
Sedation: 0.5 – 1 mcg/kg, titrated to effect
50kg Woman: mcg
80kg Man: mcg
Induction of Anesthesia:
Typical: 1-3 mcg/kg
Cardiac: 5-10 mcg/kg
Onset
Subjective: 1 min
Peak effect: 5 min

20. Fentanyl Elimination half life Clinical half life Surprisingly long
T ½ = h
Morphine = h
Hepatic elimination
Clinical half life
Short because of distribution (highly lipid soluble)

21. Elimination vs. Distribution
Rapid onset:
IV injection  vessel rich group –(BBB) CNS
Termination clinical effect is due to
Washout from brain
Distribution to clinically irrelevant tissues (muscle, fat)
Plasma concentration falls below threshold
Elimination
Exceptions to the above:
Repeat doses (fill up the inactive tissues)
Large doses
Cardiac Surgery
Infusions
ICU

22. Fentanyl & Organ Failure
Hepatic
Inactivated by hepatic metabolism
dependent on hepatic blood flow
elderly
Reduce dose, but still safe
Renal
Inactive metabolites excreted via kidneys

23. Side effects:
Nausea, Vomiting, Constipation…

24. Side effects: Depressed level of consciousness Respiratory Depression
Airway reflexes
Aspiration (fasted)
Respiratory Depression
Dose dependent decrease in respiratory rate
Hypoventilation
Hypercarbia
Hypoxia

25. Side effects: Cardiovascular No direct myocardial depressant effects
No direct vasodilating effects
BUT:
Does decrease patients sympathetic outflow
Decr HR
Decr BP
Decr vascular tone

26. Patients to be WEARY of:
Prone to respiratory depression, desaturation
COPD
Sleep Apnea
Obesity
Hypovolemic/Critically Ill
Limited distribution of drug = “sensitive”
More likely to experience apnea and hypotension
Elderly
Decreased reserve, hepatic blood flow
Slow “arm-brain” time  be patient in dosing

27. Initial Treatment of (Serious) Opioid Side Effects
Respiratory Depression:
Airway & Breathing
(Oxygen already on)
Upgrade to FM
Stimulate patient/check resp rate
Adjust upper airway (jaw thrust)
Look for respiratory effort (?obstruction)
Oral A/W, Jaw thrust
Bag Mask Ventilation (100% O2)
Antidote

28. Naloxone (Narcan) Narcotic antagonist Supplied as 0.4 mg in 1 cc
Route: IV, SC, IM, (ETT)
Onset: <2 min
Dose:
ER: 0.4mg IV, double every 2-3min until desired LOC/RR achieved
Reserve for RR = 0. ACUTE REVERSAL OF ANALGESIA
Selective reversal: dilute 0.4 mg to total of 10cc = 0.04 mg/cc
1st dose = 0.04mg IV, double q 2min until desired LOC/RR achieved
Rarely need to give more than 2-3 doses
Elimination half-life: 60-90min
Shorter that most opioid elimination half-lives
May need repeat doses or infusion

29. Fentanyl Summary Short-acting, potent analgesic
Termination of effect by distribution
Only redose after enough time for peak effect
5 min
Dose dependent respiratory depression
Oxygen for all patients
Keep an eye on the RR
Simple A&B’s will get you out of most trouble
Narcan

30. Be patient in your dosing:
You can always give some more, but you can’t take a big dose back

31. Benzodiazepines

32. Benzodiazepines Anterograde Amnesia Anxiolysis
Anticonvulsant properties
Somnolence/Hypnotic
No analgesia

33. Typical Benzos
Midazolam
Diazepam
Lorazepam

34. Midazolam Water soluble 2x more potent than diazepam
Amnesia > Sedation
Route: IV, IM, PO, IN
Supplied as:
1 mg/ml
5 mg/ml
Oral preparation (facility dependent, 2mg/ml)‏
Onset:
IV: s
Peak: min

35. Midazolam Dosing: IV 0.5 – 2.5 mg aliquots
5 min between doses (allow peak effect)
Duration: min

36. Midazolam Duration Elimination Metabolites Distribution to/from brain
Rapid hepatic clearance
Elimination
Half-time 1-4 h
Doubled in elderly
Metabolites
Partially active (50%), rapidly cleared via kidneys

37. Midazolam & Organ Failure
Hepatic
Metabolism dependent on hepatic blood flow and enzyme activity
Elderly, liver failure
Reduce dose, but still safe
Faster metabolism than other benzos
Renal
Not affected by renal failure
Caveat: renal failure + infusion (ICU setting)

38. Midazolam Side Effects Depressed level of consciousness Ventilation
Depressed airway reflexes
Ventilation
Decrease hypoxic drive (COPD)
Midazolam as sole agent
Minimal respiratory depression (unless COPD or elderly)
Synergism with other agents
Worsen respiratory depression of fentanyl
More significant than diazepam/lorazepam

39. Midazolam
Side Effects
Cardiovascular
Decr BP
Incr HR
CO maintained

40. Diazepam “Valium” ½ as potent as midazolam Long elimination time
21-37h
Directly proportional with age
Active metabolites
Renal excretion:
even longer elimination half-life
Organ failure
Hepatic: prolonged elimination
Renal: prolonged elimination

41. Lorazepam 3x as potent as midazolam PO, SL, IV, IM
Slow peak effects (20-30 minutes)
Long clinical effects (6-10 hours)
More potent sedative and amnestic
Long elimination time
10-20 hours
Non-active metabolites, no adjustments for organ failure

42. Benzodiazepines Most common side effects: Prolonged sedation
Respiratory depression
COPD
Elderly
... synergistic with other CNS depressants
Opioids etc.

43. Initial Treatment of (Serious) Benzo Side Effects
Respiratory Depression:
Airway & Breathing
(Oxygen already on)
Upgrade to FM
Stimulate patient/check resp rate
Adjust upper airway (jaw thrust)
Look for respiratory effort (?obstruction)
Oral A/W, Jaw thrust
Bag Mask Ventilation (100% O2)
Antidote

44. Flumazenil Specific and exclusive benzodiazepine antagonist
Dose dependent reversal of
Sedation
Respiratory Depression

45. Flumazenil Dosage: Duration of action
Titration to desired level consciousness
0.1 mg IV q 1 min
Typical dose 0.3 – 0.6mg to reverse side effects
mg to abolish any benzo effect
In overdose: mg/hr to maintain LOC
Duration of action
30 to 60 min
May require redosing

46. Flumazenil Side effects Nausea/Vomiting Possible seizures
Chronic benzo user
On anti-epileptic drugs

47. Local Anesthetics

48. Classification Amides Esters Lidocaine Bupivacaine Ropivacaine ...
Chloroprocaine
Procaine
...

49. Typical Use
Infiltration
?Blocks

50. +/- Epinephrine Vasoconstrictor Decrease systemic absorption
Decrease risk of toxicity
Increase duration of block
Greatest effect with lidocaine
Less so with bupivacaine

51. +/- Epinephrine Contraindications: Anything that could fall off:
Fingers/Toes
Ears
Nose
Ankle  foot
Male genitalia
Unstable Cardiac condition
CAD etc
Arrhythmia

52. Infiltration Agent Lidocaine Bupivacaine Ropivacaine Max Dose+
350/500*
175/225*
200
mg/kg
5/7*
2.5/3.2* 3
Duration (min)
30-120
60-360
* = with epinephrine
+ Assumes 70 kg patient

53. Systemic Toxicity
Due to excess plasma concentration of any local anesthetic drug
Different agents have different thresholds for major effects, but all can cause toxicity
Main concerns
Neurologic
Cardiovascular

54. Neurologic Toxicity:
Dose dependent effects (with increasing plasma concentrations):
(Cardiovascular depression)
Coma, Respiratory arrest
Seizures, Unconsciousness
Lightheadedness, Tinnitus, Numbness of tongue
Analgesia

55. Cardiovascular Toxicity:
Progression to (with increasing plasma concentrations):
Sinus bradycardia, ventricular dysrhythmias, ARREST
Decreased cardiac output, hypotension
Hypertension, tachycardia

56. Toxicity Index Ratio of the dose required to produce each
Cardiovascular Collapse : CNS toxicity
Lidocaine: ~ 7
Bupivacaine: ~ 3.7

57. Avoiding LA Toxicity: Avoid: Good practice: Overdoses (absorption)
Intravascular injection (short lived, high plasma concentration)
Good practice:
Give less than maximum dose
Avoid intravascular injection
Aspirate prior to injection
Incremental dosing
Use of epinephrine (where appropriate)
Signs of intravascular injection (tachycardia, hypertension)
Decrease rate of absorption

58. Treatment of LA Toxicity
Avoidance
Neurologic symptoms (i.e. Seizures)
Supportive
ABC’s
Acidosis/hypoxia worsens effects of toxicity
Oxygen
+/- Ventilate
+/- ETT
Increase seizure threshold
Midazolam
Thankfully brief

59. Treatment of LA Toxicity
Cardiovascular symptoms
Supportive
Call for HELP (CODE)
ABC’s
Control a/w
Oxygen
Ventilate +/- intubate
Fluids
Cardiopulmonary bypass (bupivacaine)
Intralipid (bupivacaine)
Lipid emulsion (similar to propofol carrier)