General Anesthesia II, Introduction to General Anesthesia Flashcards
- General Anesthesia is:
Reversible process of depression of the central nervous system with drugs that produce unconsciousness
ideal anesthetic technique has these 3 components?
-loss of consciousness
-stability of systems
-analgesia
what is analgesia? are all anesthetics analgesics?
– Reduced or absent perception of pain
* Some anesthetics are analgesics; however not all anesthetics are analgesics
ADVANTAGES OF PRE-MEDICATION
- Sedation to facilitate handling of patient
- Lowers the dose of induction anesthetic drugs
- Lowers the dose of inhalational anesthetics
– Decreases MAC - Smooth induction
– Calm, non-anxious patient - Smooth recoveries
– If pre-medication drug(s) is still present in sufficient amounts in blood/tissues during recovery phase - ± Analgesia
common drug combos for induction?
– Diazepam or Midazolam + Ketamine
– Diazepam or Midazolam + Propofol or Alfaxalone
– Opioid + Benzodiazepine
* Need to be sick for this to work
– Propofol and Ketamine
– Inhalational anesthetic
ADVANTAGES OF INJECTABLE
INTRAVENOUS
Rapid induction
Rapid control of airway (intubation)
Rapid adjustments in depth of anesthesia
Smooth loss of consciousness
All Injectable routes:
No environmental pollution
Sophisticated equipment not required
DISADVANTAGES OF INJECTABLE
- Restraint required for IV administration
- Dependence on patient hepatic and renal function for metabolism and excretion
- Cardiopulmonary depression if administered inappropriately
– Requires knowledge and monitoring - Association of a prolonged recovery when used for the maintenance of anesthesia
– Exception- propofol & alfaxalone
INDUCTION WITH INHALANTS how does it work? what are the methods? what problems may arise?
- Deliver a high concentration from the start with a relative high O2 flow
- Deliver desired concentration in gradual increments with relative high O2 flow
– Odour of inhalant may cause aversion and struggling (excitement) - Isoflurane has strong odour
INDUCTION WITH INHALANTS how does it work? what are the methods? what problems may arise?
- Deliver a high concentration from the start with a relative high O2 flow
- Deliver desired concentration in gradual increments with relative high O2 flow
– Odour of inhalant may cause aversion and struggling (excitement) - Isoflurane has strong odour
ADVANTAGES WITH INHALANTS
- Lack of requirement of an intravenous access
– But there is a risk if problems arise - Rapid recovery with newer agents
– There is no requirement of metabolism or excretion of these drugs to terminate their effect
DISADVANTAGES OF INHALANTS
- Requirement of sophisticated equipment
- Significant cardiopulmonary depression when used at high doses
– Dilution of inhalant in the anesthetic system and uptake by the patient counteracts the delivered concentration - Excitement/discomfort
- Pollution
INTUBATION purpose and advantages
- Secures the airway
- Spontaneous or mechanical breathing
- Seals the airway with cuffed endotracheal tube
- Minimizes risk of aspiration
- LESS environmental contamination if using inhalant anesthetics
- Minimizes airway resistance
- Large diameter tubes IDEAL
- Maximize the inspired oxygen fraction
- Allows delivery of inhalant anesthetics
- Allows ventilation
DISADVANTAGES OF INTUBATION
- Damage to larynx
- Laryngospasm
– More likely in cat, sheep, pigs - Over-inflated cuff
– Compresses the tracheal mucosa and may cause ischemia - Long tubes
– May result in endobronchial intubation (one-lung ventilation)
GENERAL ANESTHESIA OPTIONS
Maintenance
1. Inhalational Anesthesia only
2. PIVA- partial intravenous anesthesia
3. TIVA- total intravenous anesthesia
what is PIVA- partial intravenous anesthesia
Combined use of inhalation and intravenous anesthetics to produce the desired degree of general anesthesia
