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You are in Home >> Exams >> Mitchell Anaesthetic Notes

Remote anaesthesia

Created: 29/11/2006
Updated: 8/1/2007

Anaesthesia in a hyperbaric chamber

  • Hyperbaric chamber
    • Increased atmospheric pressure, usually up to 3 atm
      • Commonly chamber contains air, but oxygen headboxes or masks are used to deliver high FiO2
    • Indications
      • CO poisoning, gas embolism, decompression illness
      • Acute infections, sports injuries
      • Maintenance of oxygen transport in anaemia
      • Increased arterial oxygenation in anaesthesia
  • Physiological effects
    • Increased barometric pressure
      • Pressure reversal of anaesthesia requires much higher pressures
    • Increased partial pressure of oxygen, risk of toxicity
  • Practical use
    • Limited duration
      • Oxygen toxicity
      • Decompression obligation
      • Monitoring difficulty
      • Patient discomfort
    • Equilibration
      • Middle ear and lung
  • Equipment
    • Increased fire hazard so minimal use of electrical devices
    • Monitors usually placed outside chamber with long cables
      • Pressure devices need adjustment
      • Catheter balloons need deflation prior to compression or decompression (e.g. Swan)
      • Blood gas assessment is complicated by decompression of sample
    • Defibrillation is hazardous
    • IV giving set air-fluid level changes with pressure change
    • Anaesthetic machine
      • Flow meters under read
      • Vaporizers deliver same partial pressure but reduced vol%
      • Special ventilators required
  • Anaesthesia
    • Trials in
      • Carotid, caesarean, lung lavage

Would you anaesthetize in a dental surgery?

College Policy T5 (1995)

  • Principles of anaesthetic care
    • Suitable medical practitioner
    • Medical preanaesthetic consultation
    • Compliant monitoring
    • Anaesthetist has discretion to cancel cases
  • Staffing
    • Assistant to the anaesthetist
    • Assistance for positioning
    • Technical assistance for equipment service
  • Equipment
    • Anaesthetic machine for each anaesthetizing location
      • Calibrated vaporizers
      • Suitable breathing systems
      • Paediatric breathing systems if children are being anaesthetized
      • Safety devices
        • Indexed gas connection, oxygen reserve supply, oxygen failure warning device, oxygen analyzer, anti-hypoxic interlock, pressure relief valve, non-slip common gas outlet connection, scavenging
    • Separate ventilating device with independent oxygen supply
    • Compliant suction equipment
    • Other equipment
      • Gloves, masks, eye protection etc.
      • Stethoscope, sphygmomanometer, compliant monitoring
      • Range of face masks, airways, ETTs and connectors
      • Two laryngoscopes and a range of blades
      • Introducers, syringe, clamps, Magill’s forceps, tapes, scissors, lube, throat pack
      • Tourniquets, IV equipment, sharps container
      • Regional equipment
      • Defibrillator
  • Environment
    • Good lighting
    • Emergency lighting
    • Telephone or intercom
    • Refrigerator
    • Environmental temperature control
    • Chair which allows rapid head-down or horizontal positioning
  • Drugs
    • Anaesthetic agents
    • Emergency drugs for initial management of
      • Anaphylaxis, arrhythmias, cardiac arrest, pulmonary oedema, hypotension, hypertension, bronchospasm, respiratory depression, hypoglycaemia, hyperglycaemia, adrenal dysfunction, malignant hyperpyrexia (dantrolene at nearby hospital), coagulopathy
    • Mechanism for checking use-by dates
  • Maintenance
    • Routines for checking equipment
    • Twice yearly service of anaesthetic machine with documentation
    • Protocol for checking the anaesthetic machine
  • Recovery
    • Compliant recovery room
    • Contingency plan for emergency transfer to hospital care

Problems in transporting patients

  • Assistance
    • Two staff minimum for patient transport
      • One to resuscitate, one to get help
      • At least one must be familiar with the route and destination
  • Airway and breathing
    • If intubated, the ETT must be well-secured
    • Ventilation
      • Apnoeic for short periods (e.g. induction room to OR)
      • Self-inflating bag
      • Gas-powered ventilator (e.g. Dräger Oxylog)
      • Battery-powered ventilator (e.g. some Siemens models, Dräger Julian)
    • Portable oxygen source adequate for expected duration of transport
    • Portable suction
    • N2O and anaesthetic vapours usually not available
      • Vaporizers do not operate correctly when shaken
  • Circulation
    • External pacing device must have adequate battery power and leads secure
    • Intravenous infusions must have adequate length and be well-secured
      • Best attached to bed
    • Warming devices will not operate without AC power
    • Circulatory support devices must have adequate tubing length and battery power and triggering not subject to interference (e.g. IABP, LVAD)
  • Monitoring
    • SpO2, ECG, NIBP or invasive pressure usually available
      • Adequate lead length and battery power required
    • Gas analysis, complex monitors usually not available
    • Vibration in transport may interfere with all monitors
      • Greater dependence on clinical signs: pulse, colour, chest movement
      • Conflicts with need to keep patient covered and warm
  • Drugs and equipment
    • Awake patient
      • Emergency induction drugs and airway equipment
    • Maintenance of anaesthetized patient
      • Sedative or hypnotic agents
        • e.g. midazolam, morphine, thiopentone, propofol
      • Relaxants
        • Longer-acting agents preferred
    • Emergency drugs
      • Resuscitation drugs, pressors
      • Specific agents depending on patient’s condition
        • e.g. anticonvulsants, vasodilators
  • Other
    • Surgical drains
      • Chest drains clamped or placed so as to ensure no “backflow”

College Policy: Minimum Standards for Transport of the Critically Ill (P23)

  • Administrative guidelines
    • Central coordination to minimize delays
    • Clear determination of responsibility
    • Appropriate documentation
    • Quality assurance mechanism
  • Categories of transport
    • Prehospital, interhospital (emergency and semi-elective), intrahospital
  • Staffing
    • Prehospital: appropriate ambulance service personnel
    • Interhospital: experienced medical, nursing, technical and ambulance staff
      • Specifically trained personnel for neonatal and infant transport
    • Intrahospital: appropriate medical and nursing personnel
  • Transport
    • Vehicle determined by availability, urgency, distance, conditions
    • Requirements for safety, space, gases and energy, access, lighting, temperature control, restraints, noise and vibration, speed, communication, pressurization, headsets for auditory alarms
    • Special issues with aircraft: pressure, space, motion, noise
      • Fundamental requirement for stable vital signs, secure airway, secure IV, secure catheters and appropriate monitoring before departure
  • Equipment
    • Regard to size, weight, durability, battery life, restraint
    • Respiratory
      • Oxygen, airways, masks, nebulizer, self-inflating bag with PEEP, suction, ventilator with pressure and disconnect alarms, intubation set, cricothyroidotomy set, pleural drainage set
    • Circulatory
      • Monitor, defibrillator, pacer, oximeter, anaeroid sphygmomanometer, cannulae, fluids, pump set, infusion pumps, arterial pressure transducer, syringes, needles, MAST
    • Other
      • NGT, IDC, Cophenylcaine, instruments, sutures, dressings, prep, gloves, insulation, thermometer, splints
    • Drugs
      • Resuscitation drugs for all likely emergencies
        • Arrest, hypotension, hypertension, arrhythmia, APO, anaphylaxis, bronchospasm, hypoglycaemia, hyperglycaemia, raised ICP, uterine atony, adrenal dysfunction, narcotic depression, convulsions, agitation, pain, vomiting, electrolyte disturbance
  • Monitoring
    • Appropriate to the situation
    • Clinical monitoring is fundamental
    • Circulation: pulse and BP
    • Respiration: frequent assessment
    • Oxygenation: observation and pulse oximetry
    • Minimum standards
      • O2 supply failure alarm, pulse oximeter, disconnect or ventilator failure alarm, high airway pressure alarm, ECG

Kindly provided by Dr James Mitchell from his pharmacodynamics series

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