9. ANAESTHESIA OUTSIDE A HOSPITAL SETTING Flashcards
Clinical governance
In
all cases where anaesthesia services are provided, a record
must be kept, even if this is limited to a retrospective progress
note
all cases should be recorded in a central database
or registry, and all adverse events should be subjected to a morbidity and mortality review process.
Knowledge, skills and personal preparation
Practitioners must fully understand
the environment’s and mission’s demands, including duration,
working conditions, baseline infrastructure requirements of
self-care, self-sustainability, physical demands, what personal
protective equipment (PPE) is required, environmental hazards,
endemic diseases, and requirements for vaccination
the practitioner must be competent to work and care for
themselves in the environment so as not to be an additional
burden on other staff, or in turn, become a casualty.
Equipment for out-of-hospital anaesthesia
- Patient monitoring devices which can read and display heart rate, O2 saturation and NIBP. ECG and capnography monitoring and the ability to automatically record measurements for later recall are highly advisable.
- Basic diagnostic equipment including stethoscope, pupil
torch and blood glucose test kit. Expanded POC diagnostics including handheld blood gas and chemistry, Hb concentration, core temperature and field US are desirable. - Advanced airway equipment and adjuncts which allow the full standard spectrum of airway management, including face mask ventilation, intubation, rescue supraglottic airway device placement, and front-of-neck access.
- Provision for suctioning is essential, whether using a hand-held manual device or pump apparatus.
- A means of providing ventilation independent of pressurised gas supplies must be present.
- A means of providing supplemental O2 is highly recommended. This may be from cylinder supply or through the use of an O2 concentrator.
- Equipment for IV access, including disposables and appropriate fluids. In transport environments where height limitations reduce the ability to achieve sufficient gravity pressure for infusions, pressure bags and/or infusion pumps are advisable.
- A securely packaged and well-selected range of anaesthetic,
analgesic and resuscitation medications is essential. Specific
reversal agents such as naloxone and flumazenil should be included. Careful consideration should be given to whether a specific antidote to rare anaesthetic complications can or should be included (such as provision for malignant hyperthermia or local anaesthetic systemic toxicity). - Equipment must be available for patient positioning. This may be a portable operating table, gurney or bed, or may be improvised using a stretcher, cot or wilderness equipment.
Ideally, it must allow 360-degree access to the patient, leg elevation, and the ability to rapidly put the patient in the left lateral position. - An independent, hands-free light source of sufficient (ideally adjustable) brightness and suitable colour temperature is essential. This may be a simple commercially available headlamp, adequate room lighting or portable theatre lights.
Medical gasses in the austere/remote setting
Prehospital ventilators usually rely on pressurised O2 from
cylinders but may incorporate a piston or turbine, which allows
varied inspired oxygen fraction (FiO2), or ventilation with air in
the absence of an O2 source. Care must be given to the estimation
of the duration of ventilation depending on the O2 demand
and capacity available, especially when ventilators use O2 as a
drive gas. In the austere setting, it often falls to the anaesthetist
to assess and manage gas supplies and scavenging/vacuum.
Medical air, N20 and scavenging are rare. Where electrical power
is available, O2 concentrators are an excellent alternative to
cylinders, require little maintenance and have excellent service
lifetimes but are limited in output flow and pressure to drive
many conventional anaesthesia devices. In this setting, even low
flow rates can give a high FiO2 when used in conjunction with a
draw-over anaesthesia system (see next section). Suction may be
manual or by using stand-alone pumps, and scavenging may be
limited to venting exhaust gasses into the atmosphere. Attention
should thus be given to good ventilation of anaesthesia spaces.
Draw-over anaesthesia
practitioners should
undergo specific training and initial supervised practice on
draw-over systems before use for anaesthesia. The application
of standardised checklists before use is highly recommended.
Intravenous anaesthesia
avoidance of requirement for
vaporisers and complex gas administration systems
In very constrained settings, ketamine
by intramuscular bolus or drip-controlled infusion is widely used,
but the increasing capability and compactness of TCI syringe
drivers make this option attractive and familiar where electrical
power is available.
Performance of out-of-hospital anaesthesia: Patient assesment
- Patients should be assessed before anaesthesia. In the prehospital environment, this may amount to a primary survey concurrent with resuscitative efforts; in a humanitarian setting, it may occur with screening days before surgery.
Performance of out-of-hospital anaesthesia: Preparation
- Preparation of the area and patient should occur before the provision of anaesthesia. This may include positioning, creation of 360-degree access, and equipment preparation
using a standardised ‘kit dump’ so that all items are immediately at hand.
Performance of out-of-hospital anaesthesia: Practitioner
- Out-of-hospital anaesthesia care should not be initiated without a dedicated practitioner, who is ideally supported during critical phases (such as peripheral nerve blockade
or airway management) by a suitably trained assistant.
Patients under anaesthesia in the out-of-hospital setting must always have a dedicated practitioner providing care who is not also undertaking other clinical interventions (such as surgery).
Performance of out-of-hospital anaesthesia: Team briefing
- Before or concurrent with preparation, the care team
should be briefed on the plan, anticipated steps, and initial
responses to adverse events.
Performance of out-of-hospital anaesthesia: Safety checklist/ algorithms
- The use of algorithms and challenge-response checklists is
highly recommended during the preparation, briefing and
performance phases
Performance of out-of-hospital anaesthesia: Regional anaesthesia
- Local, regional and neuraxial anaesthesia are desirable in highly resource-constrained settings. The core prerequisites are practitioner experience and capability with the chosen technique, and having suitable skills, equipment, and med-
ications immediately available to deal with complications (such as LA systemic toxicity or high spinal anaesthesia).
The absence of skills or equipment to perform general anaesthesia or advanced resuscitation is a contraindication, not an indication, to use loco-regional anaesthesia. Field-
expedient peripheral nerve blocks which do not require needle positioning adjacent to critical structures (such as the pleura or large vessels) should be preferred.
Performance of out-of-hospital anaesthesia: Oxygen supply/ Preoxygenation
- Where available, O2 supplementation and preoxygenation should always be provided. Exceptions include procedures
purely under regional anaesthesia, and where draw-over anaesthesia is provided in the absence of supplemental O2 supplies. Ideally, adequate time for preoxygenation or measurement of end-tidal expired O2 fraction of > 0.8 should always be achieved before induction of general anaesthesia.
Performance of out-of-hospital anaesthesia: GA agent selection
- Agent selection for general anaesthesia should be based on
safety, titratability, and broad utility across various settings.
Ketamine is favoured as IV anaesthesia for its preservation
of spontaneous ventilation, relative cardiovascular stability,
wide therapeutic index, and multiple administration
methods. Sevoflurane is attractive as an inhalational agent
using conventional plenum or draw-over vaporisers,
although the utility of halothane and isoflurane to be used
interchangeably in the same vaporiser is desirable in some
settings
Performance of out-of-hospital anaesthesia: Advanced airway management
- Advanced airway management in the out-of-hospital setting should follow the accepted guidelines in the field. Attempts at intubation should be limited, and progression through the airway algorithm prompted by the assistant according to the preanaesthesia team briefing. Equipment for the entire airway algorithm must be immediately at hand (prepared in the kit dump) if not already open and prepared. It is not
necessary to wait for the onset of hypoxaemia to progress through the chosen algorithm if attempts are unsuccessful.
