Anesthetics (General) Flashcards
A variety of drugs are used in general anesthesia with the overall aim of ensuring _____________, _____________, ____________, _______________, and in some cases _________________
Unconsciousness
Analgesia
Amnesia
Loss of reflexes of the autonomic NS
Muscle relaxation/paralysis
General anesthesia is a ______________________ resulting from the administration of one or more general anesthetic agents
Medically induced coma (with loss of protective reflexes)
Anaesthesia is induced with either a ________ drug or with a(n) _____________-administered drug
volatile
intravenously
Anesthesia is maintained with a(n) ____________ or _______________ anaesthetic
intravenous
inhalational
Analgesics , usually _______________, are also used in general anesthesia
short-acting opioids
In general anesthesia, the use of neuromuscular blocking drugs necessitates ______________.
intermittent positive-pressure ventilation
Following surgery, _________________ can be given to reverse the effects of neuromuscular blocking drugs used in GA
acetylcholinesterase inhibitors
Individual requirements vary considerably and the recommended doses are only a guide. Smaller doses are indicated in ___________, ____________, or ____________ patients and in significant _____________, while robust individuals may require larger doses.
ill
shocked
debilitated
hepatic impairment
A ______________ can be used to reduce pain at the injection site when GA is being administered
local topical anaesthetic
The required dose of ____________ may be less if the patient has been premedicated with a sedative agent or if an opioid analgesic has been used.
induction agent
The required dose of induction agent may be less if the patient has been _____________ with a ____________ or if a(n) ______________ has been used.
premedicated
sedative agent
opioid analgesic
Intravenous anaesthetics may be used either to ____________ anaesthesia or for ____________ of anaesthesia
induce
maintenance
Intravenous anaesthetics nearly all produce their effect in one ______________ time.
arm-brain circulation
Extreme care is required in surgery of the ____________, ___________, or ___________ where the airway may be difficult to maintain
mouth
pharynx
larynx
To facilitate tracheal intubation, induction is usually followed by a ________________ or a ________________.
neuromuscular blocking drug
short-acting opioid
The doses of all _____________ drugs should be titrated to effect (except when using ‘rapid sequence induction’); lower doses may be required in premedicated patients.
intravenous anaesthetic
What is the purpose of ‘rapid sequence induction and intubation’ (RSII)?
To induce anesthesia in patients who are at higher risk of aspiration of gastric contents into the lungs
The aim is to intubate the trachea as quickly and safely as possible and is employed during emergency surgery
What is involved in ‘rapid sequence induction and intubation’ (RSII)? (5)
- Pre-oxygenation
- IV induction using predetermined induction dose, followed immediately by NM blocking agent
- Cricoid pressure (to occlude the esophagus and prevent regurgitation)
- Insertion of tracheal tube
- Mechanical ventilation of the lungs
*opioids may be used
What is the main difference between rapid sequence intubation and routine tracheal intubation?
In RSI, the practitioner does not typically manually assist the ventilation of the lungs after the onset of GA and cessation of breathing, until the trachea has been incubated and the cuff has been inflated
*this is why pre-oxygenation is so important (maximizes the oxygen available to the patient from their functional residual capacity during induction)
_________________ is a technique in which major surgery is carried out with all drugs given intravenously
Total intravenous anesthesia
In _________________, respiration can be spontaneous, or controlled with oxygen-enriched air. Neuromuscular blocking drugs can be used to provide relaxation and prevent reflex muscle movements
Total intravenous anesthesia
The main problem to be overcome in _________________ is the assessment of depth of anaesthesia.
Total intravenous anesthesia
The main problem to be overcome in total intravenous anesthesia is _________________.
the assessment of depth of anaesthesia
Which drugs are used for IV anesthesia? (4)
- Propofol (most widely used)
- Thiopental sodium
- Etomidate
- Ketamine
Is propofol used for induction and/or maintenance of anesthesia?
Both induction and maintenance
Is thiopental sodium used for induction and/or maintenance of anesthesia?
Induction
What side-effects are associated with thiopental sodium induction in GA? (2)
- Dose-related CV and respiratory depression
2. Sedative effects that persist for 24 hours (slow recovery especially after repeated doses)
____________ is a barbiturate that is used for induction of anaesthesia, but has no analgesic properties
Thiopental sodium
Which GA induction agents are administered intravenously? (4)
- Propofol
- Ketamine
- Etomidate
- Thiopental sodium
Is etomidate used for GA induction and/or maintenance?
Induction
Is ketamine used for GA induction and/or maintenance?
Induction AND maintenance
Which IV anesthetics can be used for induction AND maintenance of GA?
Propofol and ketamine
Which IV anesthetics are used for GA induction ONLY?
Etomidate and thiopental sodium
_____________ is associated with rapid recovery and less hangover effect than other intravenous anaesthetics
Propofol
_____________ can also be used for sedation during diagnostic procedures and sedation in adults in intensive care.
Propofol
Thiopental sodium is a barbiturate that is used for induction of anaesthesia, but has no ____________ properties
analgesic
Awakening from a moderate dose of thiopental sodium is ___________ (slow/rapid) because the drug redistributes into other tissues, particularly fat.
Rapid
Is metabolism of thiopental sodium fast or slow?
Slow; sedative effects can occur particularly after repeated doses
Etomidate is an intravenous agent associated with __________ (rapid/slow) recovery __________ (with/without) a hangover effect
Rapid
Without
Etomidate causes _________ (more/less) hypotension than thiopental sodium and propofol during induction
Less
Like ketamine
Etomidate produces a ___________ (high/low) incidence of extraneous muscle movements
High
can be minimised by an opioid analgesic or a short-acting benzodiazepine given just before induction
_______________ produces a high incidence of extraneous muscle movements, which can be minimised by an opioid analgesic or a short-acting benzodiazepine given just before induction
Etomidate
Is ketamine often used in GA?
Rarely used
Mainly for pediatric anesthesia, particularly when repeated administration is required
Ketamine causes _____________ (more/less) hypotension than thiopental sodium and propofol during induction
Less
Like etomidate
Recovery from ketamine is relatively __________ (fast/slow) and there is a ___________ (high/low) incidence of extraneous muscle movements
Slow
High
What is the main disadvantage of ketamine?
high incidence of hallucinations, nightmares, and other transient psychotic effects
The transient psychotic effects of ketamine can be reduced by a ______________
Benzodiazepine (eg diazepam or midazolam)
Inhalational anaesthetics include ___________ and ______________
gases
volatile liquids
Volatile liquid anaesthetics are administered using calibrated vaporisers, using _______, _______, or ____________ as the carrier gas.
air
oxygen
nitrous oxide-oxygen mixtures
To prevent hypoxia, the inspired gas mixture of inhaled anesthetics should contain a minimum of _____% oxygen at all times.
25
Higher concentrations of oxygen (greater than 30%) are usually required during inhalational anaesthesia when nitrous oxide is being administered.
Higher concentrations of oxygen (greater than 30%) are usually required during inhalational anaesthesia when ___________ is being administered.
nitrous oxide
Are volatile liquid anesthetics used for induction and/or maintenance of anesthesia?
Induction AND maintenance
Also, may be used for maintenance following induction with an IV anesthetic
At are the different types of volatile liquid anesthetics? (3)
- Isoflurane
- Desflurane
- Sevoflurane
Isoflurane is a(n) ___________ anaesthetic
volatile liquid
______________ is generally stable during isoflurane anaesthesia, but heart-rate can rise, particularly in younger patients.
Heart rhythm
During administration of isoflurane, ____________ and _____________ can fall, owing to a decrease in _____________
Systemic arterial pressure
cardiac output
systemic vascular resistance
During administration of isoflurane, systemic arterial pressure and cardiac output can _________ (rise/fall), owing to a _____________ (increase/decrease) in systemic vascular resistance
Fall
Decrease
_________________ occurs with isoflurane administration and the effects of _____________ drugs are potentiated
Muscle relaxation
muscle relaxant
What is the preferred inhalational anesthetic for use in obstetrics?
Isoflurane
How does desflurane compare to isoflurane?
Desflurane is reported to have about one-fifth the potency of isoflurane
Emergence and recovery from anaesthesia with desflurane are particularly __________ (slow/rapid) because of its ________ (high/low) solubility.
Rapid
Low
Desflurane ________ (is/ is not) recommended for induction of anaesthesia as it _______ (is/is not) irritant to the upper respiratory tract
Is not
Is
How does sevoflurane compare to desflurane?
More potent than desflurane
Emergence and recovery from sevoflurane are particularly rapid, but _________ (faster/slower) than desflurane.
Slower
Is sevoflurane irritant to the upper respiratory tract?
Non-irritant, therefore often used for inhalational induction of anesthesia (unlike desflurane)
_____________ is non-irritant and is therefore often used for inhalational induction of anaesthesia
Sevoflurane
Sevoflurane has __________ (little/significant) effect(s) on heart rhythm compared with other volatile liquid anesthetics
Little
Is nitrous oxide used for maintenance and/or induction of anesthesia?
Maintenance (in combination with other agents)
And for analgesia in sub-anesthetic concentration
For ____________, nitrous oxide is commonly used in a concentration of 50 to 66% in oxygen as part of a balanced technique in association with other inhalational or intravenous agents.
anaesthesia
Nitrous oxide is unsatisfactory as a sole anaesthetic owing to lack of ___________, but is useful as part of a combination of drugs since it allows a significant reduction in dosage.
potency
Can nitrous oxide be used as a sole anesthetic?
No, should be used in combination with other drugs (and allows a subsequent significant dose reduction of these other drugs)
_____________-administration of nitrous oxide using a demand valve is popular in obstetric practice, for changing painful dressings, as an aid to postoperative physiotherapy, and in emergency ambulances.
Self
__________ may have a deleterious effect if used in patients with an air-containing closed space since it diffuses into such a space with a resulting increase in pressure (eg pneumothorax, intracranial air after TBI, etc)
Nitrous oxide
In which clinical situations should nitrous oxide be avoided? (4)
patients with an air-containing closed space since nitrous oxide diffuses into such a space with a resulting increase in pressure
- Pneumothorax
- Intracranial air (after head injury)
- Entrapped air following recent underwater dive
- Recent intra-ocular gas injection
Which drugs are typically used for maintenance of general anesthesia? (6)
Most commonly inhaled anesthetics…
- Isoflurane
- Desflurane
- Sevoflurane
- Nitrous oxide (in combination with another)
But IV anesthetics may also be used…
- Propofol
- Ketamine
What are the phases of general anesthesia? (3)
- Induction
- Maintenance
- Emergence
What is malignant hyperthermia?
Rare but potentially lethal complication of anesthesia (most commonly volatile anesthetics and suxamethonium chloride)
Characterized by a rapid rise in temperature, increased muscle rigidity, tachycardia, acidosis
What are the symptoms of malignant hyperthermia? (4)
- Rapid rise in temperature
- Increased muscle rigidity
- Tachycardia
- Acidosis
What are the most common triggers of malignant hyperthermia? (2)
- Volatile anesthetics
2. Suxamethonium chloride
What is the treatment of malignant hyperthermia?
Dantrolene
What are the common or very common side effects of propofol? (6)
- Apnea
- Arrhythmias
- Headache
- Hypotension
- Localized pain
- Nausea/vomiting
What are the rare but dangerous side effects of propofol? (6)
- Epileptiform seizures (may be delayed)
- Pancreatitis
- Pulmonary edema
- Soft tissue necrosis
- Heart failure
- Rhabdomyolysis
What is propofol infusion syndrome?
Prolonged infusion of propofol (exceeding 4mg/kg/hr) may result in potentially fatal effects, including metabolic acidosis, arrhythmias, cardiac failure, rhabdomyolysis, hyperlipidemia, hyperkalemia, hepatomegaly, and renal failure
Is propofol safe to use in pregnancy?
Yes, but may depress neonatal respiration
Max dose for maintenance is 6 mg/kg/hr
Is propofol safe to use in patients with hepatic and/or renal impairment?
Use with caution
Is monitoring required for patients taking propofol?
If risk of fat overload OR if sedation longer than 3 days
What advice should be given to patients and carers regarding propofol? (2)
For a short GA, the risk of driving or undertaking skilled tastes should be considered for at least 24 hours after admission
The dangers of taking alcohol should also be emphasized during this period
What are the contraindications to using thiopental sodium on a patient? (2)
- Acute porphyrias
2. Myotonic dystrophy
What are the common side effects of thiopental sodium? (2)
- Arrhythmias
2. Myocardial contractility decreased
Is thiopental sodium safe to use in hepatic and/or renal impairment?
Consider dose adjustment
What are the common or very common side effects of etomidate? (7)
- Apnea
- Hypotension
- Movement disorders
- Nausea/vomiting
- Respiratory disorders
- Skin reactions
- Vascular pain
______________ following administration of etomidate can be reduced by administering an opioid analgesic or a short-acting benzodiazepine just before induction
Extraneous muscle movements
What are the contraindications to administering ketamine? (7)
- Acute porphyrias
- Eclampsia and pre-eclampsia
- Head trauma
- HTN
- Raised ICP
- Severe cardiac disease
- Stroke
What are the common or very common side effects of ketamine? (11)
- Anxiety
- Abnormal behavior
- Confusion
- Diplopia
- Hallucinations
- Increased muscle tone
- N/v
- Nystagmus
- Skin reactions
- Sleep disorders
- Tonic clonic movements
What are the rare but dangerous side effects of ketamine? (4)
- Apnea
- Hemorrhagic cystitis
- Drug-induced liver injury
- Arrhythmias
Incidence of hallucinations following administration of ketamine can be reduced by premedication with a _____________
Benzodiazepine
Patients should be advised to avoid breastfeeding for at least ___________ after their last dose of ketamine
12
Can ketamine be prescribed in patients with hepatic and/or renal impairment?
Caution and consider dose reduction in hepatic impairment
Exposure of patients to nitrous oxide for prolonged periods, either by continuous or by intermittent administration, may result in ________________ owing to interference with the action of vitamin B12
megaloblastic anaemia
Depression of white cell formation may also occur
In patients receiving nitrous oxide for prolonged periods, ______________ effects can occur without preceding overt haematological changes
neurological toxic; due to interference with the actions of vit B12
Is breastfeeding safe for patients taking nitrous oxide?
Yes, may be resumed as soon as mother has recovered sufficitnety from anesthesia
Are there any monitoring requirements for patients taking nitrous oxide?
Assessment of plasma B12 concentration should be considered in those at risk of deficiency including the elderly, those who have a poor, vegetarian, or vegan diet, and those with a history of anemia
Assessment of plasma-vitamin B12 concentration should be considered in those receiving nitrous oxide who are at risk of deficiency, including _____________, those who have ____________, and those with a _____________.
the elderly
a poor, vegetarian, or vegan diet
history of anaemia
Nitrous oxide should not be given continuously for longer than ____________ or more frequently than every ____________ without close supervision and haematological monitoring.
24 hours
4 days
What are the common or very common side effects of volatile inhaled anesthetics? (Eg isoflurane)
- Agitation
- Apnea
- Arrhythmias
- Chills
- Cough
- Dizziness
- Headache
- Hypersalivation
- Hypertension OR hypotension
- N/V
- Respiratory disorders
What are the dangerous side effects of inhaled volatile anesthetics? (9)
- Breath holding
- Cardiac arrest
- Hemorrhage
- Hepatic disorders
- Hyperkalemia
- Malignant hyperthermia
- QT interval prolongation
- Rhabdomyolysis
- Seizures
(Frequency unknown)
__________________ is a dangerous side effect specific to isoflurane
Carboxyhaemoglobinaemia
Which drug interactions should be avoided when prescribing inhaled volatile anesthetics (eg isoflurane)?
Coadministration with other drugs that may prolong the QT interval or cause hypokalemia, leading to torsades de pointes
What common side effects are specific to desflurane?
- Coagulation disorders
2. Conjunctivitis
What common side effects are specific to sevoflurane?
- Drowsiness
- Fever
- Hypothermia
