Anaesthesia Outside the Operating Room Dr. Samanthi

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Anaesthesia Outside the Operating Room
Dr. Samanthi GodawelageSenior Registrar -
Anaesthesiology
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-Radiology Dept -Cardioversion -ECT
-Dental Anaesthesia
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Problems related to isolated environment

• Equipment might be old, not regularly serviced
  and not in standard use as in the rest of the
  hospital
• Monitoring standards may not be adequate
• Piped medical gases may not be supplied
• Other personnel may be unaware of the problems
  facing the anaesthetist
• Space may be limited by bully equipment making
  access to the patient difficult
• Poor environmental conditions (eg Lighting,
  temperature)
• Recovery facilities may not be available
• Inadequate ventilation/scavenging causing
  pollution
• Problem related to transferring patients

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Problems related to patient

• Patients who require general anaesthesia are
• Infants or uncooperative children
• Older children or adults with psychological
  behavioural or movement disorders
• Intubated patients such as acute trauma victims
  and patients receiving intensive care
• Interventional procedures radio-guidance or
  painful procedures like ECT, cardioversion which
  require amnesia

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Problems related to the procedure

• MRI related problems
• Bleeding
• Conversion from sedation to anaesthesia
• Contrast related problems
• Radiation

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Anaesthetist may be asked to administer lV
contrast to the patient

• Check the timing of injection with the
  radiographer
• Contrast is viscous and can be difficult to
  inject
• Automated contrast injectors can cause high
  pressures to be developed
• Reactions
• Renal effects
• Oral contrast can cause aspiration

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Anaesthesia for CT
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• Anaesthetist can remain in the room wearing X-ray
  protection or view the patient and monitors from
  the control room
• The CT scanner does not interfere with monitoring
  equipment, but..
• The scans are short and can be interrupted
• The patient couch moves during examination
• Temporarily interruption of ventilation to
  improve image quality immediately re-ventilate
• Patient positioning

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Anaesthesia for MRI
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• MRI has superceded CT for the examination of CNS
  and many orthopaedic conditions
• MRI uses a static magnetic field which is
  permanently on and super-imposed rapidly changing
  magnetic fields and radio-frequency currents
• Low ionising radiation is used and there are no
  known ill effects
• Everyone must be screened before entering
  magnetic area and all ferro-magnetic items
  removed
• MRI can last over an hour and an individual scan
  can last upto 20 minutes

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MRI poses several unique problems to the
anaesthetist
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• High magnetic field which is always on
• The bore of the magnet is narrow, noisy and
  claustrophobic. Access to the patient is
  difficult so air-way must be secured
• Monitoring equipment can introduce stray
  radiofrequency current causing degradation of the
  image
• The magnetic fields and radiofrequency currents
  interfere with monitoring. Currents induced in
  leads can cause burns

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Solutions for MRI Anaesthesia
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• MRI compatible anaesthetic equipment or
  anaesthetic equipment kept outside the magnetic
  field
• Monitoring during MRI
• To minimize interference, use of Faraday cage and
  low band filters
• ECG the ECG is distorted by the magnetic field
  due to currents induced on leads
• Pulse oxymetry-prone to interference and burns
• Capnography- for monitoring of adequacy of
  ventilation and as a disconnect alarm
• Blood pressure-automated blood pressure
  recording can be performed using extended cable
  and nylon threads on cuff attachment. Invasive
  blood pressure measurements need long extension
  tubing

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• Anaesthesia for ECT
• Electroconvulsive therapy (ECT) is an effective
  treatment for severe depression often not
  responding to drug treatment
• General anaethesia is used to provide a brief
  period of amnesia and modify the motor effects of
  the seizure to protect the patient
• Physiologic effects of ECT
• Electrical stimulus- brief period of muscular
  contraction followed by the tonic and then clonic
  phases of the seizures
• Cardiovascular effects of ECT- immediate
  parasympathetic response followed within seconds
  by a sympathetic response
• The muscular activity of the seizure and the
  increased sympathetic activity causes a rise in
  myocardial oxygen consumption, increases CMRO2,
  cerebral blood flow, intracranial, intra-ocular
  intra-gastric pressure briefly

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• Contraindications
• Recent myocardial infarction, intracranial
  pathology
• Anaesthetic management
• Many have medical problems
• Effects of long term psychotropic drugs
• An appropriate period of fasting is difficult to
  guaranty
• Patients may already have had several
  anaesthetics
• Pre-oxygenation and IV access
• Induction agent
• Sux to reduce muscle contraction
• 100 O2 till spontaneous breathing resumes

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Anaesthesia for Cardioversion
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• Elective Cardioversion
• Adequate fasting and IV access.
• Emergency Cardioversion
• Haemodynamically compromised patient
• un-fasted patient
• Dose of induction agent should be adequate
• To obtund the hypertensive response to intubation
• But care must be taken not to compromise the
  blood pressure further

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Thank You