Anesthesiology Flashcards
1
Q
Who was the first person to use N2O clinically?
A
Horace Wells
2
Q
Who was the first anesthesiologist?
A
John Snow
3
Q
What was Carl Koller first with?
A
Use of cocaine in ophthalmology
4
Q
What is the major inhibitory neurotransmitter?
A
GABA
5
Q
What is the major excitatory neurotransmitter?
A
Glutamate
6
Q
What is the ASA physical status classification system?
A
A system for assessing the fitness of patients before surgery.
- Healthy person.
- Mild systemic disease.
- Severe systemic disease.
- Severe systemic disease that is a constant threat to life.
- A moribund person who is not expected to survive without the operation.
- A declared brain-dead person whose organs are being removed for donor purposes.
If the surgery is an emergency, the physical status classification is followed by “E” (for emergency) for example “3E”
7
Q
What is monitored during anaesthesia?
A
- Arterial blood pressure (obligatory)
- Usually non-invasively - ECG (Obligatory)
- 12 lead if possible
- Also gives heart rate - Pulsoxymetry (Obligatory)
- Capnometry (obligatory)
- Measures exhalder CO2 from the body - Central venous pressure, Pulmonary artery catheter
- Obligatory in cardiac procedures
- Normal central venous pressure is between 2-5 mmHg
- PAC is done by Swan-Ganz catheter - Temperature
- Surface temperature is important in long surgeries
- Esophageal temperature is measured in thoracic in abdominal operations - Nerve stimulation
- Gives you an idea of how much neuromuscular relaxants the patient needs
8
Q
What preanesthetic medications can be used and what are the indications?
A
- H2-blockers
- Used to reduce gastric acidity
- Used in pregnant women, emergency surgery, patients with hiatal hernia, morbidly obese - Benzodiazepines
- Used to relieve anxiety and facilitate amnesia. - Opioids
- Used to reduce postoperative pain - Antihistamines
- Used to avoid allergic reactions - Antiemetics
- Prevents nausea and possible aspiration of stomach contents - Anticholinergics
- Used to prevent bradycardia and secretion of fluids into the respiratory tract
9
Q
What is minimum alveolar concentration (MAC)?
A
It is used as a measure of potency, defined as the % gas concentration determined to produce immobility to noxious stimuli in 50% of patients. Essentially, the higher the MAC, the less the potency of the gas for sedative purposes.
10
Q
What factors affect anesthetic uptake?
A
- Solubility in blood
- Alveolar blood flow
- The difference in partial pressure between alveolar gas and venous blood
11
Q
Why does lipid solubility matter when it comes to anesthetics?
A
Because higher lipid solubility means more potency
12
Q
What are inhaled anesthetics primarily used for?
A
Maintenance of anesthesia after administraion of an IV agent
13
Q
What are factors that increase MAC (and makes the patient more sensitive to anesthesia)?
A
- Hyperthermia (>42 degrees)
- Drugs that increase CNS catecholamines
- Chronic ethanol abuse
14
Q
What are factors that decrease MAC (and makes the patient more sensitive to anesthesia)?
A
- Increased age
- Hypothermia
- Pregnancy
- Sepsis
- Acute ethanol poisoning
- Concurrent administration of IV anesthetics
- a2-adrenergic agonists
15
Q
Nitrous oxide
A
- MAC = 105%
- It is an NMDA receptor antagonist
- Can cause analgesia, depersonalisation, derealisation, dizziness, euphoria, sound distortion
- Depresses myocardial contractility but stimulates sympathetic nervous system
- Dilates coronary arteries (Very potent)
- Does NOT relax muscles (unlike other inhalation anesthetics)
- Decreases renal blood flow (which leads to decreased urinary output)
- Long term exposure can cause reproductive side effects in pregnant women
16
Q
Halothane
A
- Mostly been replaced in developed countries
- MAC = 0,75%
- Sensitizes the heart to arrythmogenic effects of sympathomimetic agents
- Lowers blood pressure and cardiac output
- Causes rapid, shallow breathing
- Depresses clearance of respiratory tract mucus
- Lowers cerebral vascular resistance and increases cerebral blood flow
- Reduces renal blood flow
- Can cause Halothane hepatitis (1/35000)
- Use with care in patients with intracranial mass lesions => possibility of intracranial hypertension due to increased cerebral blood flow
17
Q
Isoflurane
A
- MAC = 1,2%
- Causes low blood pressure, but cardiac output is maintained by a rise in heart rate due to a partial preservation of carotid baroreflexes
- Increases skeletal muscle blood flow
- Decreases systemic vascular resistance
- Dilates coronary arteries (not as potent as N2O)
- Decreases renal blood flow
- Potentiates non-depolarizing neuromuscular blocking agents
18
Q
Desflurane
A
- MAC = 6,0%
- Very low solubility in blood and tissues => causes rapid induction and emergence
- 1/4 potent as the other volatile agents
- Ultrashort duration of action, moderate potency
- Decreases tidal volume but increases respiratory rate
- Dose-dependant decrease in the response to peripheral nerve stimulation
19
Q
Sevoflurane
A
- MAC = 2,0%
- Useful in pediatric patients as inductiondue to its nonpungency and rapid increase in alveolar anesthetic concentration
- Fast and smooth induction
- May prolong QT-interval, unknown significance
- SVR and BP decreases, but less than with isoflurane or desflurane
20
Q
Barbiturates
A
- They depress the reticular activating system (RAS).
- They bind to GABA type A receptors and potentiate the action of GABA
- Example of a barbiturate: Thiopental
21
Q
Do barbiturates alter the blood flow in the brain?
A
Yes, they constrict cerebral vasculature causing a decrease in cerebral blood flow, cerebral blood volume and intracranial pressure
22
Q
Benzodiazepines
A
- Binds to a different site on the GABA-receptors
Examples of benzodiazepines:
- Diazepam
- Midazolam
- Lorazepam
Antidote:
- Flumezanil
- Apnea is uncommon, but can occur with even small doses of benzodiazepines!
- Should not be used routinely during labour because of resultant temporary hypotonia and altered thermoregulation in the newborn
23
Q
Ketamine
A
- NMDA-receptor antagonist
- It dissociates the thalamus from the limbic cortex
- Increases BP, HR and cardiac output
- Used for IV induction of anesthesia in settings where sympathetic stimulation is needed, such as hypovolemia or trauma
- May cause hallucinogenic effects
24
Q
Etomidate
A
- Depresses reticular activating system (RAS)
- Mimics inhibitory effects of GABA
- 30-60% incidence of myoclonus with etomidate induction
- Minimal effects on the cardiovascular system
- Can produce adrenocortical suppression
25
Propofol
- Most commonly used IV agent for induction of anesthesia
- Produces unconsciousness within 30-40 seconds
- Decreases systemic vascular resistance => decreased blood pressure
- Propofol formulations can support the growth of bacteria, so sterile technique must be observed in preparation and handling
26
Opioids
- Principally used to produce analgesia, although they can give sedation in large doses
- Opioid receptors are distributed throughout the nervous system
- CNS effects: Analgesia, sedation, euphoria, nausea and vomiting, miosis, depressed ventilation, depression of vasomotor centre
- Respiratory effects: Antitussive, bronchospasm in susceptible parts
- Cardiovascular effects: Bradycardia
- GIT effects: Reduced persitalsis => constipation and delayed gastric emtpying
Examples of opioids:
- Morphine, fentanyl, oxycodone
27
What are some important questions to ask the patient before anesthesia?
1. When was the last time you had anesthesia?
2. Did you have any problems with the anesthesia?
3. Do you have any allergies?
4. Have you had any blood tests done in the last 6 months?
5. Have you had an X-ray in the last 2 months?
6. Do you take any medications?
7. Any drinking problem?
8. Any blood disorder?
28
What is the Mallampati score?
A test that helps you assess the difficulty of intubiation
29
What is Thyromental distance?
Thyromental distance measurement is a method commonly used to predict the difficulty of intubation
It is measured from the thyroid notch to the tip of the jaw with the head extended.
If it is less than 7.0 cm with hard scarred tissues, it indicates possible difficult intubation.
30
What is delayed emergence from general anesthesia?
Failure to regain consciousness within 60-90 minutes following general anesthesia
31
What are causes for delayed emergance from general anesthesia?
Common causes:
- Residual anesthetics
- Sedative and analgesic effects
Other causes:
- Hypothermia
- Hypoxemia and hyperarbia
- Hypercalcemia
- Hypermagnesemia
- Hyponatremia
- Hypo/hyperglycemia
- Perioperative stroke
32
What medications are given in case of delayed emergance from general anesthesia?
Naloxone (0,2 mg)
- Blocks the effects of opiods
Flumezanil (0,5 mg)
- Reverses effects of benzodiazepines
Physostigmine (1-2 mg)
- Reverses neuromuscular blocking
33
What is the definition of hypotension in the OR?
- We need to know preanesthesia BP and what medications the patient takes
- A drop in systolic BP > 40-50 mmHg from baseline
- Systolic value <95 or mean arterial pressure <65 may be considered as criteria for hypotension
34
Which position is safest for a central venous line?
Usually the right side of the body because the veins are shorter and they are easier to reach.
1. Subclavian
2. Jugularis (2nd due to a lot of nerves passing by it)
3. Femoral (Can only be used for short times due to high infection rates)
35
What is important when placing a central venous line in jugularis interna?
Position of the patient. The patient should lie with the head down due to risk of air embolism.
