Anesthesia in Remote Locations: Radiology and Beyond

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Anesthesia in Remote LocationsRadiology and
Beyond

• Irene P. Osborn, MD
• Mount Sinai Medical Center
• New York, NY

2
Lecture Plans

• Understanding of the goals for anesthetic
  management in a remote setting
• Review of considerations and techniques for
  magnetic resonance imaging (MRI) and other remote
  areas
• Explore safe techniques for various procedures

3
Mount Sinai Medical Center

• 1000 beds
• Anesthesia department
• 150 faculty/trainees
• 15 nurse anesthetists
• Over 50,000 anesthetics/year
• 12,000 procedures performed outside the OR

4
Considerationsfor Remote Procedures

• Anesthetic Equipment-must maintain ASA standards
• Scheduling for efficient use of time
• Type of procedure,level of anesthetic
  intervention
• Recovery-where and when

Anesthesiology 84459, 1996.
5
Risk factors associated with sedation
complications

• Depth of sedation/anesthesia
• Skill and training of practitioner
• Age of the patient
• Drugs used
• Monitors used

6
Why bother?

• OR is very comfortable and familiar
• We know where everything is and have lots of help
• Outside locations can be a hostile environments
  in many ways

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Why you should go

• Provide comfort and safe conditions for
  procedures
• Demonstrate the abilities of the anesthesia
  department
• Learn new techniques
• Its a break from the OR

8
Anesthesia Standards Outside the OR

• Anesthesia equipment should be of the same
  caliber as that in the OR
• Pre-anesthetic evaluation process should be the
  same as that for patients undergoing surgical
  procedures

9
ASA Guidelines

• Reliable source of Oxygenwith back-up
• Piped O2 encouraged, 1 full bottle
• Checked before cases begin
• Reliable suction
• Anesthetic gas Scavenger
• Equipment
• Self inflating bag capable of FiO2 90
• Adequate Drugs, Monitoring Equipment
• Standard Anesthesia machine (if inhalational
  used)

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Monitoring Includes

• 1) Ventilation (Etco2, visual, precordial)
• 2) Oxygenation (pulse Ox)
• 3) CV status (EKG)
• 4) Temp
• 5) Neuromuscular function (if given a NMB)
• 6) Positioning (moving tables etc...)

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Potential complications

• Respiratory depression
• Cardiovascular instability
• Drug reaction

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Risks of Anesthesia at Remote Locations

• ASA Closed Claims Project database (1990-)
• 87 remote location claims
• Pts older, sicker and in need of emergency care
• More likely to involve sedation vs GA

Metzner JI, ASA Newsletter 20107417-18
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Metzner J, Posner KL, Domino KB. The risk and
safety of anesthesia at remote locations. The US
closed claims analysis. Curr Opinion
Anaesthesiol. 200922502-508
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Metzner J, Posner KL, Domino KB. The risk and
safety of anesthesia at remote locations. The US
closed claims analysis. Curr Opinion
Anaesthesiol. 200922502-508
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DISTINGUISHING MONITORED ANESTHESIA CARE
(MAC) FROM MODERATE SEDATION/ANALGESIA
(CONSCIOUS SEDATION)

• Committee of Origin Economics (Approved by the
  ASA House of Delegates on October 27, 2004 and
  last amended on October 21, 2009)

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Monitored anesthesia care (MAC) includes

• Diagnosis and treatment of clinical problems that
  occur during the procedure
• Support of vital functions
• Administration of sedatives, analgesics,
  hypnotics, anesthetic agents or other medications
  as necessary for patient safety
• Psychological support and physical comfort

ASA House of delegates- 2008
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MAC

• Monitored anesthesia care may include varying
  levels of sedation, analgesia and anxiolysis as
  necessary
• If the patient loses consciousness and the
  ability to respond purposefully, the anesthesia
  care is a general anesthetic, irrespective of
  whether airway instrumentation is required

ASA House of delegates- 2008
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Anesthesia outside the OR

• Emergency Department
• ICU
• CCU
• PACU
• OB
• Radiology
• Psychiatric Ward/Hospital
• Dental Clinic
• Endoscopy
• Office based
• Private Clinics

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MRI

• Painless
• Beautiful studies

• Magnetic field
• Specialized equipment
• Lack of access
• Longer studies
• Movement delays procedure

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MRI Techniques

• TIVA (propofol)
• Volatile agent with ETTor LMA
• Miscellaneous- pentobarbital, chloral hydrate,
  ketamine

• Presence of IV
• Availability of machine, ventilator

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MR Techniques - Propofol infusion

• Presence of IV
• Following mask induction
• Infusion pump/buretrol
• Maintenance dose 100-180 ug/kg/min

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Propofol total intravenous anaesthesia for MRI
in children

• 100 children for MRI
• 93 had no signs of airway obstruction
• Mean infusion rate 193ug/kg/min
• No resp or cardiac complications
• Mean time from scan to discharge- 44 min
• Good preservation of upper airway patencyand
  recovery

Usher A, et al. Pediatric Anesthesia 1523, 2005
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MRI - compatible infusion pump

• Medrad
• 1-2 separate infusions
• Close proximity to scanner

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LMA for MRI

• Easily inserted
• Provides patent airway
• Tolerated with minimalanesthesia
• Smooth emergence
• Potential cuff artifact

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Sedation and Anesthesia Protocols Used for
Magnetic Resonance Imaging Studies in Infants
Provider and Pharmacologic Considerations

• Dallal P, et al
• Anesth Analg 2006103863

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Study On Pediatric Sedation

• 258 infants who required MRI
• Chloral hydrate vs Pentobarbital vs Propofol
• The time to discharge was longest in the
  pentobarbital and shortest in the propofol group
• Infants in the chloral hydrate group moved more
  frequently during MRI scanning (with four
  sedation failures of 102) compared to 12.2 in
  the pentobarbital group and 1.4 in the propofol
  group

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MRI Anesthesia

• Mask induction w sevoflurane
• IV, ETT
• Maintenance with sevoflurane

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Do you stay in the scanner?Why?

• If pt is unstable
• Study requires suspended respirations
• Sound is 90-100 decibels
• No one can hear YOU scream

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a2 Agonists

• Clonidine
• Selectivitya2 a1 20011
• T1/2 ß 10 hrs1
• PO, patch, epidural2
• Analgesic adjunct1
• IV formulation not available in US

• Dexmedetomidine
• Selectivitya2 a1 162013
• T1/2 ß 2 hrs3
• Intravenous3
• Primary sedative
• Only IV a2 available for use in the US

1. Maze. White paper 2000.2. Khan etal.
Anesthesia. 199954150.3. Kamibayashi, Maze.
Anesthesiology. 2000931345-1349
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Sedation
Analgesia
Amnesia
Anxiolysis
Hypnosis
a2 Agonists
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Dexmedetomidine sedation in a pediatric cardiac
patient scheduled for MRIElizabeth T. Young, MD

• 8 month old infant with congenital cardiac
  defects
• 5 mg of propofol followed by infusion of dex at
  .4 ug/kg/hr
• Headphones on infant to shield from noise
• Stable course and rapid recovery

Canadian Journal of Anesthesia 52730-732 (2005)
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Conclusions

• Chloral hydrate, pentobarbital and midazolam are
  unfavourable for MRI sedation
• Dexmedetomidine appears to be convenient for
  sedation in patients without cardiac risk
• Propofol can be effectively used for sedation or
  anaesthesia in the presence of anaesthesiologists
  or paediatric intensivists
• General anaesthesia should be preferred in
  preterm or small children as safety and success
  are predictable

Curr Opin Anaesthesiol. 2008
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Adults for MRI
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Jaw elevation device (JED)
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MRI with JED
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MRI - Monitoring

• Capnography
• Pulse oximetry
• NIBP
• ECG
• Temperature (?)

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MRI- monitoring
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Pediatric Radiotherapy

• Painless
• Brief procedure
• Debilitated patient
• Tolerance to anesthetic?

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CT scan

• Usually shorter than MRI
• Considerable radiation exposure
• Procedure may be interrupted for patient
  interaction/care

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CT scan8 y.o. for CT scan-stereotactic radiation
neurofibroma
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CT scan
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Dexmedetomidine for pediatric sedation for
computed tomography imaging studies

• 62 patients (mean age- 2.8 yrs)
• Loading dose followed by infusion
• Patients were then maintained on 1 mcg/kg/hr
  infusion until imaging was completed
• 15 decrease in HR and MAP
• No change in resp rate
• Mean recovery time was 32 /- 18 minutes.

Mason K, et al Anesth Analg 2006 10357
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Interventional Radiology Procedures

• Angiography/ embolization
• PIC lines
• Ureteral stents
• Trauma interventional procedures

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Complications minor

• Contrast reactions
• Femoral artery hematoma/ pseudoaneurysm
• Problems related to sedation

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Airway Techniques

• Spontaneous ventilation
• LMA
• ETT

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Pre-proceduralAssessment - History

• The condition itself
• Pre-morbid state
• GERD
• Orthopnea
• Seizures
• Renal function

• Drug therapy
• anticonvulsants
• anticoagulants
• tricyclics
• cardiac medications

49
What is MAC?

• Monitored anesthesia care?
• Minimal airway control?
• Mostly apneic and cyanotic?

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Interventional Neuroradiology

• May be instead of or in preparation for surgery
• Done with coils, sclerosing agent (EtOH), or
  thrombolytic agent (tPA)
• Arterial aneurysms
• Light GETA with muscle relaxant, a-line
• Arteriovenous malformations
• Light GETA with muscle relaxant
• Acute stroke
• MAC (as light as possible) if patient cooperative

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Neuroradiology

• Endovascular embolization of AVMs
• Sclerotherapy of venous angiomas
• Balloon angioplasty of occlusive cerebrovascular
  disease
• Thrombolysis of acute thromboembolic stroke
• Embolization for epistaxis
• Aneurysm ablation

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Goals of INR Anesthesia

• Optimize/maintain intracranial dynamics,CBF
  physiology
• Provide superior operating conditions or
  diagnostic studies
• Allow for rapid return to consciousness for
  neurologic evaluation

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Complicationsof Endovascular Embolization

• Radiocontrast reactions
• Embolization of particles
• Aneurysm perforation
• Obliteration of physiologic arteries
• Embolization via dangerous arterial anastomoses

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Pelz DM, Lownie SP,Fox AJ, Hutton
C.Symptomatic Pulmonary Complications from
Liquid Acrylate Embolization of Brain AVMs

• AJNR 19951619-26

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Asystole during endovascular embolization of a
duralarterio-venous fistulain the brain

• Glaser C, Krenn C, Gruber A, et al.Anesth Analg
  891288, 1999

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Embolic Agents

• GDC coils
• NBCA glue
• Balloons
• Spheres
• Onyx

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What is Onyx?

• Liquid embolic system
• Hardens upon contact with blood/ fluids
• Reduced blood flow through AVM

59
Intracranial Aneurysms Radiology Suite vs. OR

• Location/ anatomy of the aneurysm
• Age and grade of the patient
• Skill of the facility
• Luck of the draw

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Endovascular coiling

• Anterior or posterior circulation aneurysm
• Medical contraindications to surgery
• Advanced age
• Pt. preference (unruptured)

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What is ISAT?

• International Subarachnoid Aneurysm Trial
• Multicenter prospective randomised clinical trial
• Neurosurgical clipping vs. endovascular coiling

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ISAT primary objective

• Determine whether endovascular treatment when
  compared to neurosurgical treatment would cut the
  proportion of either dead or dependent by a
  quarter one year after the procedure.

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ISAT results

• 1,594 patients
• 27.2 dead or dependent
• 30.6 after neurosurgery
• 23.7 after coiling
• Overall mortality
• 10.1 neurosurgery
• 8.1 coiling

Lancet October 26, 2002
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Anesthetic technique?
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3-D Angiogram
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Disasters

• Occlusion
• clot, intima, dissection
• manage BP, lytic therapy
• Hemorrhage
• catheter, balloon, coil, run of dye, BP
• reverse heparin
• respond to BP changes
• Surgery?

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Procedural Complications of Coiling of Ruptured
Intracranial Aneurysms Incidence and Risk
Factors in a Consecutive Series of 681 Patients

• van Rooij WJ, Sluzewsk M, et al.
• American Journal of Neuroradiology 2006
  271498-1501

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Complications of endovascular coiling

• Procedural perforation
• -from microcatheter, guidewire or coil
• Thromboembolic complication
• -clotting inside the guidewire,
• -clotting in the parent vessels caused by
  vasospasm or malpositioned coils.

American Journal of Neuroradiology 2006
271498-1501
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Aneurysm perforation!

• Decrease MAP
• Hyperventilate
• Rapid placement of coils to halt bleeding
• Urgent ventriculostomy
• Craniotomy for hematoma evacuation

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Zero bispectral index during coil embolization
of an intracranial aneurysm

• 55 yo with hemorrage into interpedencular cistern
• 2.4 cm basilar tip aneurysm (and wide neck)
• BIS and routine monitors (97 at awake state)
• After GA BIS between 40-60
• BIS decreased abruptly to 15 (aneurysm had
  ruptured)
• Immediate coiling done (pt could not be revived)

Anesth Analg 2007105887.
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Effect of clipping, craniotomy, or intravascular
coiling on cerebral vasospasm and patient outcome
after aneurysmal subarachnoid hemorrhage

• One center (515 patients)
• clipping (413 patients), coiling (79 patients) 23
  who underwent coiling as well as craniotomy
• no effect on total vasospasm or symptomatic
  vasospasm in good- or poor-grade patients

Neurosurgery. 2004 Oct55(4)779-86
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New improved tehniques!

• Softer catheters
• 3-D rotational angiography
• Consider an external drain (ventriculostomy)
  prior to coiling a ruptured aneurysm

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Airway strategiesvideo- laryngoscopy
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Video laryngoscopes -GlideScope Ranger
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Carotid artery stent

• 82 y.o retired physician for left carotid stent
  placement
• HTN, angina

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Carotid stent

• MAC/ sedation
• Hemodynamic control
• Ability to lie supine
• Potential for bradycardia/asystole with
  angioplasty
• Radial artery monitoring for close control

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LMA ProSeal

• 58 yo for angiography and possible vertebral
  artery stent
• OSA with CPAP at night
• Very anxious
• Desaturation and apnea with minimal sedation

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Post-Procedural Care

• Distance to travel to Recovery Room
• Same recovery room standards as for OR
• Recovery Room staff less familiar with procedure
• Non-surgical staff less familiar with protocols
  procedures of the Recovery Room
• Ongoing anti-coagulation monitoring and lines

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Propofol

• Sedative, hypnotic
• Respiratory depression
• Hypotension
• Anti-emetic
• How did we practice before this agent?

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Ketamine

• Analgesia
• Sedation
• Cardiovascular stability
• Bronchodilation
• Cheap!

• Tachycardia?
• Secretions
• Hallucinations

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• The Use of a Ketamine-Propofol Combination During
  Monitored Anesthesia Care
• Badrinath S et. al., Anesth Analg 200090858-62
• Summary -Premed midaz 2mg. NCO2 3L. -Propofol
  ketamine (0.94-1.88 mg/ml)
• effective deep sedation/analgesia
• 40-56 needed chin lift
• VSS
• no delay in discharge
• less opioid required intraop

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COMPARATIVE PHARMACOKINETICS
Fentanyl
Remifentanil
Alfentanil
Vdss (L/kg)
0.25-0.75
3-5
0.3-0.4
Cl (mL/min/kg)
3-8
10-20
40-60
t1/2 ? (min)
60-120
180-300
8-20
t1/2 keo (min)
0.6-1.2
4-5
1.0-1.5
Context-sensitivehalf time
50-55
100
3-6
Time required for drug concentrations in blood
or at effect-site to decrease by 50. Based on
3-hour infusion duration. Vdss Volume of
distribution at steady state Cl Clearance t1/2
keo Blood-brain equilibration half-time t1/2 ?
Terminal half-life Adapted from Egan TD et al.
Anesthesiology 199379881-892. Glass PSA. J Clin
Anesth 19957558-563.
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REDUCTION OF PROPOFOL
Relationship between Remifentanil and Propofol
for Probability of Response to Skin Incision
(n47 patients)
6 5 4 3 2 1 0
Move
No move
Target Propofol Concentration (µg/mL)
0 5 10 15 20 25 30 35 40
Remifentanil Concentration (ng/mL)
Adapted from data on file, Glaxo Wellcome Inc.
87
Anesthetic Techniques

• Sedation
• Conscious Procedural Local with Sedation
• Monitored Anesthetic Care (MAC)
• Sedation/Local with GA stand-by
• Regional
• General Anesthesia

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Advantages of TIVA

• Components can be regulated independently
• Anesthetic area remains unpolluted by trace
  concentrations of nitrous oxide/volatile agents
• Vaporizers are not needed
• Prevents delivery of hypoxic mixtures
• Non-triggering of malignant hyperthermia

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GI Endoscopy

• Colonoscopy
• Polypectomy (both pedunculated and sessile)
• Heavy MAC with midazolam and propofol infusion
• Minimal fentanyl
• Endoscopic ultrasound (EUS)
• Endoscopic retrograde cholangiopancreatography
  (ERCP)

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GI Endoscopy

• Colonoscopy
• Endoscopic ultrasound (EUS)
• Pancreatic cyst drainage, pancreatic mass biopsy
• Patients usually healthy
• Topical Cetacaine (benzocaine/tetracaine) to
  oropharynx
• Heavy MAC with midazolam and propofol infusion
• Minimal fentanyl
• Endoscopic retrograde cholangiopancreatography
  (ERCP)

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Why do they need anesthesia?

• Older, sicker patients
• New procedures
• Training of gastroenterology fellows
• Safer, more efficient practice

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Intubation for EGD?

• Patients with high risk for aspiration
• Severe Gastric reflux
• Achalasia
• Bowel obstruction
• Uncontrollable bleeding
• Otherwise patients receive MAC for upper endoscopy

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GI Endoscopy

• Colonoscopy
• Endoscopic ultrasound (EUS)
• ERCP Special Considerations
• Balloon evacuation, sphincterotomy, stent
  placement
• May be instead of or in preparation for surgery
• Patients often sick, e.g. coagulopathic,
  cholangitic
• Consider pre-procedure gram negative antibiotics,
  such as Zosyn (piperacillin/tazobactam)
• Prone position required for optimal scope
  navigation

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ERCP- Technique

• Unless morbid obesity, MAC with propofol infusion
  and ketamine
• Midazolam- 1-2 mg
• Propofol induction- 1-2 mg/kg
• 25-50mg ketamine in 20cc propofol infusion at
  30-40ug/kg/min
• Decrease/eliminate ketamine and continue with
  propofol

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Setting Up Services Outside the OR

• Modify existing facilities if necessary
• Ensure presence of necessary support services and
  equipment
• Educate involved personnel
• Establish mutually agreeable scheduling procedure