Overview of Anaesthesia Flashcards
What is an anaesthetist?
Anaesthetists are perioperative physicians who care for patients before, during, and after their journey through surgery
Differentiate between general and local/regional anaesthesia.
In general anaesthesia, patient is unconscious (induced, reversible coma). Depending on surgery and drugs used, patient may breathe spontaneous or be ventilated artificially. Analgesia administered separately
Local/regional anaesthesia- part of the body is rendered insensitive to pain and sensation by blocking nerves with a local anaesthetic agent. Patient is still fully conscious.
What is the components of the triad of general anaesthesia.
Hypnosis, analgesia and immobility
Explain what the term hypnosis refers to in anaesthesia.
Loss of consciousness.
Achieved with general anaesthetic agents (intravenous and/or inhalational).
Typically anaesthesia is induced with IV agents and maintained with inhalationals.
Most of these agents ONLY CAUSE HYPNOSIS and are not analgesic
Under pure regional anaesthesia (e.g. spinal anaesthesia) a patient will be fully awake, but if appropriate, sedative medication can be
Anaesthesia is NOT sleep, although we use the terms “asleep” and “going to sleep” and “waking up” as surrogate terms
Why is analgesia a component in the triad of general anaesthesia?
Body still experiences pain under general anaesthesia. Pain activates the sympathetic nervous system which causes harmful effects.
Thus, for patient’s comfort.
additional analgesic agents are given, usually intravenously
What is another term(used interchangeably) for immobility (w.r.t triad of genral anaesthesia)?
Muscle relaxation
What are the benefits of muscle relaxation/immobility during surgery?
An immobile surgical field is essential for optimal surgical access
Surgery in large body cavities (such as the chest and abdomen) requires the use of paralytic agents (neuromuscular blockers)
Immobility may also be required for delicate microsurgery
What occurs during the pre-induction phase of the perioperative process?
Patient assessed. Consent checked. Theatre prepared Equipment checked IV access sited Pre-induction drugs (sedatives) Patient connected to monitors Preoxygenation Opioids given
What occurs during the induction phase of the perioperative process?
Induction of anaesthesia proceeds either with intravenous or certain inhalational agents
Loss of consciousness is confirmed
The anaesthetist is now responsible for maintaining the patient’s airway
A definitive airway strategy is implemented (mask ventilation or a supraglottic airway or an endotracheal tube)
If intubation is required, a neuromuscular blocking agent needs to be administered first and requires time to start working (1-5 minutes depending on the drug used)
The airway is secured and checked
What occurs during the maintenance phase of the perioperative process?
Maintenance of anaesthesia is usually by inhalational agents
Propofol can be given via infusion instead of inhalational agents
Ventilator settings are adjusted (if used)
Additional monitoring may be sited or techniques employed (regional anaesthetic blockade to augment analgesia)
The surgical area is cleaned and prepared
Surgical, nursing, and anaesthetic staff implement the WHO Surgical Safety Checklist and discuss their concerns for the case
Surgery proceeds
The patient is monitored throughout with the anaesthetist attending to analgesic, physiologic, and surgical requirements as needed
What occurs during the emergence phase of anaesthesia?
Surgery must be concluded and the surgical and nursing teams satisfied
Returning control of respiration to the patient is crucial prior to emergence
Any muscle relaxant is checked to be reversed (reversal is given for non-depolarizing agents)
Respiration and oxygenation must be assessed to be adequate (spontaneous, regular breathing with normal vital signs)
The anaesthetic agent is discontinued
Airway devices (e.g. ET tubes) are removed either deep or on awakening
The patient is assessed on the table for a few moments before transfer onto the trolley
List and explain Guedel’s 4 stages of general anaesthesia.
Stage 1: “Analgesia”
–>from induction to loss of consciousness
Stage 2: Excitatory phase –>paradoxical disinhibition (excitement, hiccupping, swallowing, writhing about)
Stage 3: Surgical anaesthesia–>eyeballs become fixed, diaphragmatic respiration
Stage 4: Overdose: diaphragmatic paralysis, loss of all reflexes–>death
As anaesthesia deepens, what is the first reflex to leave?
Voluntary control of eye movement
As anaesthesia deepens, what is the last reflex to leave?
Pupillary light reflex.
Which reflex is quite important to note during anaesthesia, as loss of this reflexes renders the airway vulnerable to vomiting and regurgitation.
Glottic reflexes and control of respiration.
