General Anaesthesia Flashcards
Triad of genreal anesthesia:
- 1 - Unconsciousness
- 2 - Analgesia
- 3 - Muscle relaxation
1st of GA:
Analgesia and sedation
Stage of GA no longer found in modern medicine:
Erratic breathing, heart rate, nausea, pupil dilation breath-holding
Choking can occur due to irregular breathing and a risk of vomiting
3rd stage of anesthesia:
Surgical anesthesia
Begins with lackof lid reflex
4 substages:
- Roving eye balls
- Loss of corneal and laryngeal reflexes
- Pupil starts dilating and light reflex is lost
- Intercostal paralysis, shallow abdominal respiration, dilated pupils
4th potential stage of GA:
Intoxication - resp. arrest, cardiac arrest, widely dilated pupils, muscles are flabby, low BP, no pulse
Pharmacodynamics in GA is?
MAC value
PA (alveolar partial pressure) is equal to?
Input into alveoli - loss of IA from alveoli into arterial blood
Input is dependent on 3 factors:
PI (inspired partial pressure), alveolar ventilation, characteristics of anesthetic breathing system
Alveolar uptake is dependent on 3 factors:
Solubility, CO, alveolar to venous pressure difference
PA is determined by __ factors
6 (the factors affecting input and alveolar uptake
Increased PI (partial pressure)
accelerates induction
Second gas effect is typical for?
NO
Increased alveolar ventilation…
For exmaple, hyperventialtion, increases induction
Solubility:
lower blood-gas partition coefficient =
faster induction and recovery
lower CO (shock) causes ____ induction
faster induction
MAC definition:
Minimum concentration in lungs for more than 50% of people to not respond to pain
high MAC = low _____
potency
___MAC prevents movemtn in all patients
1.3
Factors increasing MAC:
Hyperthermia
Hypernatremia
Hyperthyroidism
Drugs increasing catecholamine levels (Cocaine, trycyclics, MAOI’s)
Chronic alcohol abuse
Factors decerasing MAC
Hypothermia
Hypoxia
Hyponatremia
Pregnancy
Lidocaine
Lithium
a2 agonsits
PaO2 < 38mmhg
BP <40mmhg
preoperative meds
Drugs decreasing catecholamines (clonidine, a-methyldopa, clonidine, chronic amphetamine ingestion)
Acute ethanol ingestion
Nitrous oxide
Sweet, colorless odorless
Powerful analgesic, not potent anesthetic
low potency
non-flammable, non-irritating
Inhibits B12 metabolism
MAC value = 104%
Halothane:
Halogenated alkane
Pungent odor
Thymol preservative and amber-colored bottles to retard spontaneous oxidative decomposition
Overall decrease in CVS
Rapid shallow breathing
Decreased renal blood flow
Potentiates NM relaxants
Myometrial relaxation
Decrease hepatic blood flow
Oxidative CYP450 metabolism
Halothane hepatitis (allergic rxn)
Enflurane:
Colorless
Mild, sweet etheral odor
Decreases BP
Increased sensativity to epinephrine
Increased ICP
Seizures
Decreased renal output
Potentiates relaxants
Myometrial relaxation
Decreased hepatic blood flow
Elimination primarily by ventilation
Metabolite of fluoride
Fluoride-induceed nephrotoxicity
Isoflurane
Mild, sweet, ethereal odor
Colorless
Least cardiac depression
IRRITANT TO UPPER AIRWAY
MAC value 1.3%
Desflurane:
PUNGENT ODOR
Decfrease BP
Increase HR
Increase ICP
Irritates upper airways
Sevoflurane:
Colorless
Pleasent odor
Smooth mask induction
Bronchodilator
Not irritating
Malignant hyperthermia
Hypermetabolism of skeletal muscle
Large calcium release from SR
TRIGGERED BY IA AND SUCCINYLCHOLINE
Increased CO2
Metabolic and resp. acidosis
Accelerated O2 consumption
Increased heat production
SNS activation
Hyperkalemia
DIC
Multiple organ dys. and failure
Increased end-tidal CO2, tachycardia, muscle rigidity, tachypnea
Fever, myoglobinuria, multiple organ failure
Ideal IA has ____ solubility in blood
low
3321 measurement
3 interincisial
3 hyoid-mental
2 hyoid-thyroid
1 sublaxation of mandible
Mallampati score
1 uvula fauces soft pallate pillars
2 uvula fauces soft palate
3 base of uvula, soft palate
4 hard palate
Intubation equipment
Suction
Airway
Laryngoscope - adults macintosh, curved - children miller, straight
Tube (F is 7-8mm while M is 8-9mm)
Physiological response to intubation:
HTN, tachcardia, intracranial HTN, laryngospasm
Does not cause histamine release:
Etomidate
_____ and _____ can cause histamine induced bronchospasm
Mopprhine
Meperidine
Opioid indicated in asthma:
Fentanyl
Factors not affecting MAC:
- Potassium disorders
- Duration of anesthesia
- Magnitude of anaesthetic metabolism
- Gender
- PaCO2 of 15-95mmHg
- PaO2 >38mmHg
- Blood pressure >40mmHg
Main side effect of NO
Inhibition of vit b12 metbolism
Inhlaed anesthetics basics, MAC value:
NO - MAC 104%
Halothane - Hepatitis - pungent odor
Enflurane - Sweet - Fluoride - induced nephrotoxicity
Isoflurane - sweet - IRRITANT- 1.3%
Desflurane - pungent odor - IRRITANT - 6.6%
Sevoflurane - sweet - 2%
3321 locations:
3 - interincisor
3 - thyreomental
2 - hyoid-thyroid
1 - sublaxation of mandible
Complications of endotracheal intubation:
- Trauma
- Hypoxia
- Dysrhythmias
- Aspiration
- Intubation of oesophagus or right mainstem bronchus
- Laryngospasm
- Bronchospasm
