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Anesthesia at Remote Locations


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Title: Anesthesia at Remote Locations

Anesthesia at RemoteLocations
  • Dr Abdollahi

Remote anesthesia
  • Anesthesiologists are increasingly being asked to
    provide anesthetic care in locations outside of
    the OR.
  • It is the responsibility of the anesthesiologist
    to ensure that the location meets the ASA
    guidelines for safety.

  1. Radiology suites (MRI, CTSCAN)
  2. Cardiac catheterization laboratories
  3. Psychiatric units
  4. Radiation therapy
  5. Gastroentrology
  6. Pulmonary medicine
  7. Urology (ESWL)
  8. General dentistry

  • Anesthesiologists must maintain the same high
    standard of anesthetic care provided in the
    operating suite.

  • Large, mobile pieces of radiologic equipment,
    radiation hazards, intense magnetic fields,
    paramedical personnel not familiar with the
    anesthesia team, and other factors may make the
    delivery of quality anesthetic care problematic.

  • Remember that the key to efficient and safe
    remote anesthetic relies on open communication
    between the anesthesiologist and non-operating
    room personnel

1994 Guidelines for non-operating room
anesthetizing locations
  • Reliable oxygen source with backup.
  • Suction source.
  • Waste gas scavenging.
  • Adequate monitoring equipment.
  • Self-inflating resuscitator bag.
  • Sufficient safe electrical outlets.
  • Adequate light and battery-powered backup.
  • Sufficient space.
  • Emergency cart with defibrillator, emergency
    drugs, and emergency equipment.
  • Means of reliable two-way communication.
  • Compliance with safety and building codes.

Remote monitoring
  • Qualified anesthesia personnel must be present
    for the entire case.
  • Continuous monitoring of patients oxygenation,
    ventilation, circulation, and temperature.
  • Oxygen concentrations of inspired gas low
    concentration alarm.
  • Blood oxygenation pulse oximetry.
  • Ventilation end-tidal carbon dioxide detection
    and disconnect alarm.
  • Circulation EKG, ABP (q 5min), invasive BP, and

  • Anesthesia techniques used in non-operating room
    anesthetizing locations range from no anesthesia,
    to sedation/ analgesia, to general anesthesia.

  • Radiologic procedures that may require
    sedation/analgesia include a number of imaging
    modalities such as radiology,
  • ultrasonography, CT, and MRI, as well as various
    interventions that may be directed by the imaging

  • Advances in imaging capability, as well as the
    availability of advanced endovascular devices and
    RF probes, has increased the use of radiology
    suites and increased the demand for anesthesia
    services in these areas

  • Percutaneous drain placement,
  • Nephrostomy tube placement,
  • Percutaneous placement of feeding tubes,
  • Placement of intravascular access catheters,
  • Thrombolysis,
  • Dilation of stenotic vessels,
  • Embolization of tumors or arteriovenous
    malformations (AVMs),
  • Tissue biopsy specimens may be obtained under
    radiologic guidance

Conditions may be treatable in the radiology suite
  • Some solid tumors may be treated by guided tissue
  • Painful metastases may be treated by guided
    radiofrequency (RF) ablation.
  • Cerebrovascular lesions may be treated
    endovascularly with guidance by digital
    subtraction angiography.

General consideration
  • Medical history
  • Immobile
  • Claustrophobia
  • Environment (Crowded, Bulky radiology equipment
    ,high voltage,change of position )
  • Lack of gas scavenging

Radiation Safety
  • Radiation exposure is potentially harmful both in
    terms of its somatic effects during an exposed
    individual's lifetime (e.g., production of
    leukemia) and in terms of genetic injury
    resulting in fetal abnormalities caused by damage
    to the gonadal cells or developing fetus.

  • The maximal permissible radiation dose for
    occupationally exposed persons is 5O
    millisieverts (mSv) annually, a lifetime
    cumulative dose of 10 mSv x age, and monthly
    exposure of 0.5 mSv for pregnant women.

  • Radiation exposure can be limited by wearing
    appropriate lead aprons and thyroid shields,
    using movable leaded glass screens, and using
    innovative techniques such as video monitoring
    and remote mirroring of monitor data to allow
    remote conduct of anesthesia when appropriate and
    required for the safety of anesthesia personnel.
    Clearly, open communication between the radiology
    and anesthesia teams is essential to minimize
    radiation exposure. Adequate warning of
    initiation of imaging by the radiology team
    allows the anesthesia personnel to take
    appropriate precautions in a timely fashion

Iodinated Contrast Media
  • Iodinated contrast agents are often used in
    diagnostic and therapeutic radiologic procedures
    to assist imaging.
  • Adverse reactions to contrast media range from
    mild to immediately life-threatening, and
    etiologies include direct toxicity,idiosyncratic
    reactions, and allergic reactions, either
    anaphylactic or anaphylactoid Crable

  • Predisposing factors include a history of
    bronchospasm, history of allergy, underlying
    cardiac disease, hypovolemia, hematologic
    disease, renal dysfunction, extremes of age,
    anxiety, and medications such as B-blockers,
    aspirin, and nonsteroidal anti-inflammatory
  • Prompt recognition plus treatment of contrast
    media reactions is important to prevent
    progression of less severe reactions and lessen
    the impact of severe reactions

  • Treatment is symptomatic, for example, oxygen and
    bronchodilators to treat bronchospasm. Severe or
    resistant bronchospasm may require treatment with
    epinephrine. Typically, corticosteroids and
    antihistamines are given to symptomatic patients
    under the assumption that the etiology is

  • pretreatment with prednisolone, 5O mg 12 hours
    before a procedure requiring contrast media, and
    diphenhydramine, 5O mg immediately before the

  • Renal dysfunction is well documented in
    association with radiologic contrast media,
    particularly in patients with preexisting renal
    dysfunction and most especially in patients with
    preexisting renal dysfunction related to

  • Most cases of new or worsened renal function
    related to contrast media are self-limited and
    resolve within 2 weeks.
  • However, some patients may progress to the point
    of requiring dialysis.

  • Recent studies have demonstrated a reduction in
    contrast media nephrotoxicity by the
    administration of acetylcysteine.Life-
    threatening lactic acidosis may develop in
    non-insulin-dependent diabetic patients who are
    receiving metformin and have preexisting renal
    dysfunction if their renal function declines
    further. Extra care is needed when patients
    taking metformin receive radiologic contrast

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Anesthesia in the Radiology Suite
  • Minimal to moderate sedation/analgesia is the
    technique used for most patients undergoing these

  • For most adults, combinations of intravenous
    benzodiazepines and opioids (i.e., titration of
    midazolam and fentanyl) are sufficient to ensure
    comfort during the procedure. The use of more
    potent anesthetic agents such as propofol,
    methohexital, and ketamine is best reserved for
    specialists in anesthesia.However, understanding
    the procedure in question is important in
    selection of the appropriate anesthetic
  • The patient's condition, the anticipated level of
    stimulation, and patient position during the
    procedure are all important considerations.

  • A patient undergoing ultrasound-guided hepatic
    biopsy might have ascites, which would render
    that patient prone to aspiration if sedated, and
    penetration of the hepatic capsule by the biopsy
    needle would be anticipated to be quite painful.
    Such a patient might benefit from general
    anesthesia rather than sedation/analgesia.

  • Procedures that might be anticipated to last
    several hours may best be performed with general
    anesthesia at the outset rather than late
    conversion after failure of sedation/ analgesia,
    when patient access might be limited by catheter
    placement and radiologic equipment.

  • Pediatric patients merit special consideration.
    Some radiologic procedures require patients to
    remain still for prolonged periods, which may not
    be possible for infants and children, even with
    sedation/analgesia. (chloral hydrate orally for
    radiologic procedures 25 to 5O mg/kg for infants
    younger than 4 months, 5O mg/kg for older

  • Patients with difficult airways, whether
    anticipated or not, can be problematic in
    settings outside the operating suite . I prefer
    to perform anticipated difficult endotracheal
    intubations in the operating suite with its
    improved availability of skilled assistants and
    specialized equipment. Once the airway is
    controlled, the patient can be transported to the
    site of the planned procedure
  • should it be necessary to perform the procedure
    outside the operating suite.

  • The most significant risk posed in the MRI suite
    is the effect of the magnet on ferrous objects.

  • MRI scanning has a number of limitations. Imaging
    is time consuming, and individual scans may take
    up to 20 minutes, with an entire examination
    lasting more than 1 hour.
  • Switching on and off of the RF generators
    produces loud noises (gt90 dB).

  • Hearing protection is mandatory for both the
    patient and health care personnel who must be
    present in the scanning room. Heating resulting
    from the RF energy of nonferromagnetic prosthetic
    devices has not proved to be a problem. Body
    surfaces do absorb this RF energy, but it is
    unlikely that the patient's temperature will
    increase by more than 1C.

  • The most significant risk posed in the MRI suite
    is the effect of the magnet on ferrous objects.
  • Dislodgement and malfunction of implanted
    biologic devices or other objects containing
    ferromagnetic material are also real
    possibilities. Such items include shrapnel,
    vascular clips and shunts, wire spiral
    endotracheal tubes, pacemakers,automatic
    implantable cardioverter-defibrillators (ICDs),
    mechanical heart valves, and implanted biologic

  • Tattoo ink may contain high concentrations of
    iron oxide. Burns at tattoo sites have been
    reported after exposure to MRI magnetic fields,
    but such incidents are very rare and the presence
    of, for example, permanent eyeliner should not
    exclude the patient from MRI examination.

Anesthetic Management for MRI
  • Anesthesia in the MRI suite poses several unique
    problems, including the following
  • 1. Limited patient access and visibility,
    especially when the patient must be placed head
    first into the magnet
  • 2. Absolute need to exclude ferromagnetic
  • 3. Interference/malfunction of monitoring
    equipment produced by the changing magnetic field
    and RF Currents
  • 4. Potential degradation of the imaging caused by
    the stray RF currents produced by the monitoring
    equipment and leads
  • 5. The necessity to not move the anesthetic and
    monitoring equipment once the examination has
    started to prevent degradation of magnetic field
  • 6. Limited access to the MRI suite for emergency
    personnel in accordance with the recommended
    policies noted earlier

  • A common approach now is to induce anesthesia in
    an induction area adjacent to the MRI suite
    outside the magnetic field by using conventional
    equipment with the patient on a dedicated MRI
    transport table that is not ferromagnetic.

  • Because the patient's airway is not easily
    accessed during the MRI scan and because patient
    assessment and communication are limited by both
    the magnet bore in which the patient is placed
    and the loud noise associated with MRI scanning,
    deep sedation/analgesia is not advisable.
    Patients requiring more than moderate
    sedation/analgesia are probably most safely
    administered a general anesthetic with airway
    control by either endotracheal intubation or a
    laryngeal mask airway (LMA).

Contraindications for MRI include
  • Shrapnel, vascular clips and shunts, wire spiral
    ETTs, pacemakers, ICDs, mechanical heart valves,
    recently placed sternal wire, implanted
    biological pumps, tattoo ink with high
    concentrations of iron-oxide (permanent
    eyeliner), and intraocular ferromagnetic foreign

  • Ferromagnetic items should never be allowed in
    the vicinity of the MRI magnet, including
    scissors, pens, keys, gas cylinders, anesthesia
    machine, syringe pump, beeper, phone, and steel
  • Cards with magnetic strips will be de-magnetized,
    including credit cards and ID badges.

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  • Include embolization of cerebral and dural AVMs,
    coiling of cerebral aneurysms, angioplasty of
    atherosclerotic lesions, and thrombolysis of
    acute thromboembolic stroke.

  • These procedures may involve deliberate
    hypotension, deliberate hypercapnia, or
    deliberate cerebral ischemia as part of the
    procedure a requirement for rapid transition
    between deep sedation/ analgesia and the awake,
    responsive state and severe potential procedural

Anesthetic Management
  • Preprocedural anesthetic evaluation is similar to
    that before neurosurgical procedures. Airway
    examination is important in as much as airway
    manipulation during the procedure is not possible
    because of interference with head positioning for
    imaging. Particularly important is a history of
    previous experience with radiologic procedures
    and any history of contrast media reaction.
    Because blood pressure management is important
    for these procedures, preoperative evaluation for
    hypertension is important, as is good
    preoperative control of existing hypertension.

  • Heparin is commonly administered during these
    procedures, with a target activated clotting time
    (ACT) of 2 to 2.5 times the baseline value.
    Deliberate hypotension is frequently used during
    AVM embolization to decrease flow to feeding
    vessels, as well as during some trial balloon
    occlusions. Agents such as esmolol, labetalol, or
    sodium nitroprusside are all useful in this
    situation. Deliberate hypertension is called for
    during cerebral ischemia in an attempt to
    maximize collateral flow.

  • Phenylephrine is generally used, both as a bolus
    and as an infusion titrated to increase systolic
    blood pressure 30to 40 above baseline. Close
    monitoring of ECG parameters for signs of
    myocardial ischemia is critical in this case.
    Smooth emergence from anesthesia is important in
    these patients, who may be prone to device
    migration or intracranial hemorrhage.
    Administration of antiemetics before emergence is
    certainly reasonable, and precautions to avoid
    coughing andl/bucking" should be taken.

  • lnterventional cardiology procedures include
    coronary angiography and cardiac catheterization,
    coronary artery angioplasty/stenting, valvotomy,
    closure of intracardiac defects,
    electrophysiologic studies with pathway ablation,
    and cardioversion.
  • Electrophysioiogic Studies and Catheter Ablation
    of abnormal Conduction Pathways , Pacemaker and
    Cardioverter- defibrillator implantation.

  • The usual anesthesia management is by
    sedation/analgesia, with general anesthesia
    reserved for sedation failure, uncooperative
    patients, or those who require airway control to
    manage respiratory failure.
  • Anesthetic agents used commonly include fentanyl
  • midazolam, sometimes supplemented with propofol.
  • Sedation and analgesia are helpful in reducing
    the discomfort .

  • Typical heparin doses range from 2500 to 5000 IV
    intravenously. For interventional procedures,
    higher heparin doses (i.e., 10,000 IV
    intravenously) are given, with a target ACT of
    over 300 seconds. Patients must be monitored
    carefully after protamine administration to
    detect the predictable peripheral vasodilation,
    as well as less predictable anaphylactic and
    anaphylactoid reactions or the rare catastrophic
    pulmonary vasoconstrictive crisis associated with
    protamine administration.

  • Heparin are increasingly commonly being
    administered during interventional cardiac
    catheterization and have resulted in improved
    outcomes despite the reduction in heparin dose.
    Platelet aggregation inhibitors used have
    included abciximab, ticlopidine, and clopidogrel.
    Numerous studies have shown the benefits of anti
    platelet therapy in both acute and chronic
    coronary syndromes.
  • A notable side effect of abciximab is elevation
    of the ACT
  • independent of heparin.

  • Coronary artery disease is assessed by detection
  • stenoses after injection of contrast medium
  • into each main coronary artery. Stenoses greater
  • 50to 70f the normal arterial diameter are
  • hemodynamically significant, although lesser
  • may be clinically important. Coronary artery
    disease is
  • classified as one-, two-, or three-vessel disease
    or left main
  • coronary disease.

  • after dilation of the stenotic coronary artery,
    ventricular arrhythmias may develop and require

Pediatric Cardiac Catheterization
  • Medications administered for sedation include
    fentanyl, midazolam, propofol, and ketamine.
  • Premedication with midazolam, 0.5 mg/kg orally,
    can be particularly helpful. Some evidence has
    indicated that ketamine can increase oxygen
    consumption, so care must be taken to ensure that
    it does not impair diagnostic accuracy.

  • Hypothermia
  • Arrhythmia
  • Tamponad
  • Bleeding

Elective Cardioversion
  • Elective cardioversion is uncomfortable, and
    general anesthesia is required. Many medications
    have been used, including barbiturates, propofol,
    etomidate, and benzodiazepines.

  • It should be noted that muscle relaxants are not
    typically needed for this procedure.
  • Etomidate cause myoclonus and interfere by EKG
    and airway managment.

  • Indications for ECT include major depression,
    mania, certain forms of schizophrenia, and
    perhaps Parkinson's syndrome.

  • Pheochromocytoma is a contraindication to ECT.
  • Relative contraindications include
  • Increased intracranial pressure,
  • Recent cerebrovascular accident,
  • Cardiovascular conduction defects,
  • High-risk pregnancy,
  • Aortic and cerebral aneurysms.
  • In these conditions, the risk of the patient's
    psychiatric illness and the side effects of
    antidepressant medications must be weighed
    against the risk associated with ECT and

  • ECT therapeutic effects are thought to result
    from release of neurotransmitters during the
    electrically induce grandmal seizure.

  • Seizure activity causes an initial
    parasympathetic discharge manifested by
    bradycardia, occasional asystole, premature
    atrial and ventricular contractions, or a
    combination of these abnormalities. Hypotension
    and salivation may be noted and then sympatric
  • ECG changes, including ST-segment depression and
    T-wave inversion, may also be seen after ECT
    without any of the myocardial enzyme changes
    consistent with myocardial infarction.

  • Arrhythmias associated with ECT, even in patients
    with preexisting arrhythmias, are self-limited
    and not in themselves a contraindication to
  • ECT has been found to be relatively safe even in
    high-risk cardiac patients, provided that careful
    management is provided.

  • The most common causes of death are MI and

  • Neuroendocrine responses to ECT include increased
    levels of stress hormones, including
    adrenocorticotropic hormone, cortisol, and
    arginine vasopressin, as well as prolactin and
    growth hormone.Norepinephrine and epinephrine
    increase immediately after ECT,and epinephrine
    levels decrease more rapidly thereafter. Glucose
    homeostasis is variably affected by
    ECT.Improvement in control of non-insulin-dependen
    t diabetes is generally noted, whereas
    hyperglycemia may be seen when the diabetes is
    insulin dependent.

  • Pre-op the pt. These pts have often had this
    procedure multiple time, therefore you can use
    old records as templates.
  • Place IV and give glyco (0.2 mg IV). Treats the
    bradycardia/ asystole from the initial
    parasympathetic discharge from the seizure
  • Hyperventilate the pt. with 100 O2.
  • Inflate the manual BP cuff in the arm opposite
    the IV and then give Sux.
  • Place the bite block.
  • Goal is a seizure 30-60 seconds long.
  • Ventilate until spontaneous respirations return.
  • The parasympathetic discharge is often followed
    by a sympathetic discharge associated with HTN
    and tachycardia. This is treated with esmolol.

Antidepressant Drug Therapy
  • Antidepressants, monoamine oxidase inhibitors
    (MAOIs),serotonin reuptake inhibitors, lithium
    carbonate, or a combination of these drug.

  • Tricyclic antidepressants block the reuptake of
    norepinephrine, serotonin, and dopamine into
    presynaptic nerve terminals, thereby increasing
    central sympathetic tone. Tricyclic
    antidepressants have anti. histaminic,
    anticholinergic, and sedative properties and also
    slow cardiac conduction. These side effects are
    less common with the newer types of
    antidepressant drugs such as trazodone,
    bupropion, and fluoxetine. The combination of
    centrally acting anticholinergics, such as
    atropine, with tricyclic antidepressants can
    increase postprocedural delirium.

  • MAOIs can inhibit hepatic microsomal enzymes.
    They may interact with opioid analgesics and
    cause excessive depression. Used concomitantly
    with meperidine, MAOIs may result in severe,
    possibly fatal excitatory phenomena.

  • Lithium carbonate prolongs the action of
    neuromuscular blocking agents. Elevated lithium
    levels, higher than the therapeutic range, can
    prolong the action of benzodiazepines and
    barbiturates. Patients receiving lithium may
    demonstrate more cognitive side effects after
    ECT. The American Psychiatric Association
    recommends discontinuation of lithium therapy
    before ECT.

  • Hypothyroidism is known to occur in patients who
    have been tacking lithium for long time (15 years
    or more) .

Anesthetic Management of Electroconvulsive
  • Anesthesia and neuromuscular blockade are
    necessary during ECT to prevent psychological and
    physical trauma. Rapid recovery is desirable.

  • particular attention paid to coexisting
    neurologic and cardiac disease, osteoporosis and
    other causes of bone fragility, and medications
    that the patient may be receiving. The patient
    may be a poor historian because of the
    psychiatric condition, and accompanying
    caregivers may need to provide the necessary
    history and assurance of fasting status.

  • Glycopyrrolate (0.2 mg intravenously), which does
    not cross the blood-brain barrier, can reduce the
    occurrence of bradycardia and the amount of oral
    secretions associated with ECT. After
    preoxygenation, anesthesia is administered by
    peripheral intravenous catheter, and
    neuromuscular blockade is induced. When
    relaxation is adequate and satisfactory mask
    ventilation with oxygen is ensured, a bite block
    is placed and a stimulus is delivered to induce
    the seizure.

  • If the patient has a hiatal hernia and
    gastroesophageal reflux, rapid-sequence induction
    and endotracheal intubation with cricoid pressure
    may be a reasonable approach. Adequate
    ventilation is ensured during the procedure
    because among other detrimental effects, hypoxia
    and hypercarbia decrease seizure duration and
    thus the efficacy of ECT.

  • Many intravenous anesthetics have been used to
    induce anesthesia for ECT, including
    methohexital, thiopental, propofol, and ketamine.
    Methohexital (0.75 to 1.0 mg/kg) is the most
    commonly used drug for ECT anesthesia and is
    considered the "gold standard. "Propofol (0.75
    mg/kg) was found to reduce seizure duration,
    which was believed to decrease the efficacy of

  • Thiopental(1.5 to 2.5 mg/kg) avoids pain on
    injection, but it is associated with more
    hypertension and tachycardia than propofol .

  • Etomidate may prolong seizures and recovery, but
    prolongation of the seizure may be useful in
    patients in whom seizure duration is deemed too
    short with other agents. Benzodiazepines have
    anticonvulsant activity and should be avoided
    before ECT.
  • Ketamine has been demonstrated to not increase
    seizure length or produce excessive
    postprocedural agitation.
  • Given the hemodynamic response expected after
    ECT, ketamine would seem to be a less desirable

  • Prophylactic medications have been advocated to
    avoid various side effects of ECT. Transient
    asystole is rare during ECT, but it may be
    prevented with anticholinergic pretreatment.
    Glycopyrrolate is preferred over atropine because
    glycopyrrolate has no central anticholinergic
    side effects. In addition, glycopyrrolate is an
    effective antisialagogue.

  • Both esmolol and labetalol have been successfully
    used to control hypertension and tachycardia
    after ECT.Some evidence has shown that esmolol
    reduces seizure duration.Routine treatment with
    esmolol or labetalol is not recommended because
    the hypertension and tachycardia are usually
    self-limited, as are premature ventricular
    contractions. Should treatment be necessary,
    these drugs can be administered immediately after
    the stimulus.

Extracorporeal shock wave lithotripsy(ESWL)
  • ESWL used focused shock waves (high intensity
    pressured wave of short duration) to pulverize
    renal and ureteral calculi into very small
    fragment which are then washout by normal urine

  1. Electrohydrulic lithotripsy (immersion)
  2. Nonimmersion lithotriptor (shock tube)

  • No pain
  • Immobile is necessary
  • Immersion cause increase CVP and increase WOB
    and shallow breathing and rapid. Decrease VC and
  • Arrhythmia (best is shock delivered 20 mesc
    after Rwave )
  • Hypertension or hypotension
  • CHF ,MI
  • Hematuria
  • Pulmonary contusion and pancreatitis
  • Flank pain for several days
  • Petechia and soft tissue swelling (1)
  • No interface with pacemaker

Management of anesthesia
  • Sedation /analgesia
  • GA or RA (T6)
  • LMA
  • Adequate intravenous fluid for washout

Dental surgery
  • Anesthesia is necessary for very young or
    mentally patients.
  • CHD (down )

Management of anesthesia
  • Rapid induction and prompt recovery
  • Ketamine IM for induction for IV line
  • Sevoflurane
  • Intubation
  • Antiemetic drug
  • Short acting opioid

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