CHAPTER 5: General Considerations of Anesthesia and Management of the Difficult Airway Flashcards
Goal of airway management
Provide the most expeditious form of management that has the lowest potential for injury and the greatest potential for control of the airway
Fasting recommendation for clear liquids
2 hours
Fasting recommendation for breast milk
4 hours
Fasting recommendation for other food or beverages (infant formula and milk)
6 hours
Pharmacologic agents administered preoperatively may reduce the risk of aspiration
- Clear antacids (30 ml of Na citrate)
- Anticholinergic agents (atropine or glycopyrrolate)
- Metoclopramide (to stimulate gastric emptying and increase lower esophageal sphincter tone)
- H2- receptor antagonists (cimetidine or ranitidine) to decrease secretion of HCl
Most common used IV anesthetic agent
Propofol
TRUE or FALSE
Propofol will cause a 25% to 40% drop in BP with 15% to 20% drop in cardiac output
TRUE
TRUE or FALSE
Induction doses of propofol cause central apnea
TRUE
TRUE or FALSE
Propofol has inherent bronchodilating effects that favor its use is asthmatic patients
TRUE
TRUE OR FALSE
Propofol has antiemetic properties
TRUE
A dissociative anesthetic that produces unconsciousness without ablating spontaneous respiration, swallowing, eye movement, or airway protective reflexes
Ketamine
Most commonly used benzodiazepine in the preoperative setting because its onset of activity is within 2 to 4 minutes
Midazolam
Most commonly used benzodiazepine in the preoperative setting because its onset of activity is within 2-4 minutes
Midazolam
3 main task of anesthesiology team
- Keep the patient safe
- Keep the patient comfortable
- Provide for optimal conditions during the preoperative, intraoperative, and immediate postoperative periods
The component qualities of a general anesthetic are
- Loss of consciousness
- Amnesia
- Analgesia
- Muscle relaxation/paralysis
These standards include continual evaluation of the patient’s oxygenation, ventilation, circulation, and temperature during all administered anesthetic
Standards for Basic Anesthetic Monitoring
Basic anesthetic monitoring should include
- Continuous oxygen analysis of the anesthetic circuit
- Pulse oximetry
- Continuous waveform capnography
- Tidal volume measurement
- ECG
- Temperature measurement
- Intermittent measurement of arterial BP and HR
To assess the degree of muscle paralysis and the return of muscle strength after pharmacologic reversal of paralyzing agents
Twitch monitor
True or False
Ketamine can increase a patient’s BP, HR and cardiac output through sympathomimetic effects and release of stored catecholamines
True
Other unique properties of ketamine
- Can administered IM
- Analgesic properties
- Increase salivary production
True or False
Etomidate has neutral effects on BP and cardiac output
True or False
Etomidate will also suppress the patient’s adrenal glands
True
Given preoperatively for their sedative, anxiolytic and amnestic effects
Benzodiazepines
True or False
Benzodiazepines will produce anterograde amnesia
True
True or False
In sedative doses, benzodiazepines produce mild respiratory depression
True
True or False
Coadministration of benzodiazepines with opiods can synergistically produce profound respiratory depression
True
Used intraoperatively to provide analgesia and balanced anesthesia
Opiods
The most commonly used opiods are
- Fentanyl
- Remifentanil
- Sufentanil
- Morphine
- Hydromorphone
Antagonist of opiods
Naloxone (u-receptor)
True or False
Doses of lidocaine kept to 1 to 1.5 mg/kg to avoid potential toxicity
True
True or False
Lidocaine can also be administered prophylactically into the same IV line as propofol to reduce propofol-induced venous irritation and patient discomfort
True
A newer anesthetic agent that works as an a-2 agonist to reduce sympathetic nervous system outflow and produce a sedative effect that more nearly mimics normal sleep
Dexmedetomidine
Been used for sleep endoscopy to pinpoint the area of pharyngeal obstruction prior to uvulopalatopharyngoplasty
Dexmedetomidine
The most commonly seen hemodynamic effect of Dexmedetomidine
Bradycardia
The most potent but slowest and longest acting of the currently available volatile anesthetics
Isoflurane
Contraindicated during middle ear surgery because it can expand in a closed air space
Nitrous oxide
It impairs methionine synthase, which may cause an increased rate of surgical wound infections
Nitrous oxide
True or False
The volatile anesthetic agents are not often used for induction of general anesthesia in adults, but they are the most commonly used agents for maintenance of GA
True
Characterized by uncontrolled skeletal muscle metabolism that leads to hyperthermia, acidosis, rhabdomyolysis, and sometimes death
Malignant hyperthermia
The most commonly agent for TIV
Propofol
-mixes of ketamine and propofol may also be used to balance the hemodynamic effects
Commonly used during suspension laryngoscopy
Remifentanil
Two classes of paralytic agents:
- Depolarizing agents
2. Nondepolarizing neuromuscular blockers
Only depolarizing paralytic agent
Succinylcholine
Acts on acetylcholine receptors in the neuromuscular junction, activating the receptors but then occupying them, thereby prolonging the refractory period before the muscle can contract again
Succinylcholine
Major advantage of succinylcholine
Very fast onset of action
Succinylcholine:
Paralysis sufficient for endotracheal intubation can be reliably produced within
45-60 seconds
Succinylcholine is metabolized and deactivated by
Pseudocholinesterase
Clinical paralysis of succinylcholine usually dissipates within
5-8 minutes
Most common muscle relaxant trigger for MH
Succinylcholine
Primary contraindications to the use of succinylcholine:
- Known or suspected MH
- Increased ICP
- Increased IOP
- Elevated serum K
Nondepolarizing agent of choice for RSI in whom succinylcholine use is contraindicated
Rocuronium
* onset action between 60 and 75 seconds
Marked disadvantage of Rocuronium
Given in doses sufficient for intubation, persists for 40-40 minutes
A newly available reversal agent that binds Rocuronium and Vecuronium, thus removing neuromuscular bloackade
Sugammadex
In CNS, it prevents reuptake of neurotranmitters, including dopamine and NE
Cocaine
Most commonly used anesthetics for local infiltration or nerve blocks
Lidocaine and Bupivacaine
True or False
Local anesthetic toxicity manifests initially as CNS depression and seizures followed by cardiovascular dysrhythmias with the potential for ventricular fibrillation
True
True or False
The maximum dose of lidocaine (5mg/kg) may be increased (to 7mg/kg) if epinephrine is used in the solution to slow uptake from the subcutaneous tissues into the general circulation
True
The maximum dose of Bupivacaine + Epinephrien solution
2-3 mg/kg
True or False
Local anesthetics can produce toxic effects at much lower doses if they are administered directly into the circulation
True
Most commonly used drugs for intraoperative control of hypertension and tachycardia related to airway management
- Beta blockers esmolol and metoprolol
2. Mixed alpha and beta-blocker labetalol
“ A clinical situation in which a conventionally trained anesthesiologist experiences difficulty with facemask ventilation of the upper airway, difficulty with tracheal intubation, or both”—ASA
Difficult airway
System of 3 classes to predict a difficult airway based on the position and visibility of certain anatomic structures (Mallampati)
- Uvula
- Fauces
- Soft palate
System of four grades to predict a difficult airway based on the position and visibility of certain anatomic structures (Modified Mallampati/Cormack an d Lehane)
- Glottic aperture
- Posterior arytenoids
- Epiglottis
Other physical predictors of anticipated difficulty with conventional direct laryngoscopy include
- Prominent overbite
- Receding chin
- Large tongue
- Narrow mouth opening (interincisor distance or gap)
- Short neck
- Limited neck flexibility
- Obesity
Other ways to predict a difficult airway use a measurement of the
Thyromental distance or the sternomental distance
LMA
Laryngeal mask airway
