Anesthesia 2nd year Flashcards
To determine the etiology of hypoxemia, calculate the?
A-a gradient to narrow thedifferential diagnosis
When other causes have been ruled out, persistent and refractory hypotension in trauma or other critically ill patients may be caused by (2)
hypocalcemia
hypomagnesemia
Speed of onset of volatile anesthetics is increased by (4)
Increasing the
- Concentration
- Fresh gas flow
- Alveolar ventilation
- Using non-lipid soluble agents
Termination of effect of intravenous anesthetics is by ________________ , not biotransformation and breakdown.
Redistribution
- Lipid solubility, pKa, and protein binding of the local anesthetics determine their _______, _________, and _____________, respectively
- Potency
- Onset
- Duration
When compressed, some gases condense into a liquid such as (2) and some do not such as (2)
- N2O and CO2
2. O2 and N2
Most commonly used anesthesia circuit?
What are its components (6)?
- Semiclosed circuit using a circle system
- inspiratory limb
- expiratory limb
- unidirectional valves
- CO2 absorber
- Gas reservoir bag
- Pop-off valve on the expiratory limb
Every patient ventilated with an ascending bellows anesthesia ventilator receives approximately ___ cm H2O of positive end-expiratory pressure (PEEP) because of the weight of the bellows.
2.5 to 3 cm H2O
The first step in the care of the hypoxic patient fighting the ventilator is to?
Ventilate the patient manually with 100% oxygen
Risk factors for auto-PEEP include (4)
- High minute ventilation
- Small endotracheal tube
- Chronic obstructive pulmonary disease
- Asthma
Below a hemoglobin saturation of ____, a small decrease in saturation corresponds to a large drop in PaO2.
90%
Except for visualization with bronchoscopy, _____ is the best method of verifying
endotracheal tube location.
CO2 detection
If a patient’s ______ is excellent, even in the presence of ischemic heart disease, the chances are good that the patient will be able to tolerate the stresses of surgery.
Exercise capacity
The necessary criteria for acute lung injury/acute respiratory distress syndrome (ALI/ARDS) include: (5)
(1) Acute onset
(2) PaO2/FiO2 ratio of 300 for ALI
(3) PaO2/FiO2 ratio of 200 for ARDS
(4) Chest radiograph with diffuse infiltrates
(5) Pulmonary capillary wedge pressure of 18 mm Hg
Mechanical ventilation settings for patients with ARDS or ALI include tidal volume of at _____ of ideal body weight while limiting plateau pressures to ______ cm H2O. FiO2 should be adjusted to maintain
oxygen saturations between __________.
6 to 8 ml/kg
<30 cm H20
88% and 92%
Measures to acutely decrease intracranial pressure (ICP) include (4)
- elevation of the head of the bed
- hyperventilation (PaCO2 25 to 30 mm Hg)
- diuresis (mannitol and/or furosemide)
- minimized intravenous fluid
Malignant hyperthermia (MH) is an inherited disorder that presents in the perioperative period after exposure to inhalational agents and/or succinylcholine. The disease may be fatal if the diagnosis is delayed and dantrolene is not administered. The sine qua non of MH is an unexplained rise in \_\_\_\_\_\_\_\_\_\_, with a simultaneous increase in \_\_\_\_\_\_\_\_\_\_\_, in the setting of an unexplained, \_\_\_\_\_\_\_\_\_\_\_.
Rise in end-tidal carbon dioxide
Increase in minute ventilation
Unexplained tachycardia
In patients with ___________ spinal anesthesia should be used with caution and only in situations in which the benefits of spinal anesthesia over general anesthesia are clear.
Multiple sclerosis
The inability to touch the palmar aspects of the index fingers when palms touch (the ____sign) can indicate a difficult oral intubation in patients with diabetes.
Prayer sign
The initial goal of burn resuscitation is to correct ________.
Hypovolemia
Abrupt oxygen desaturation while transporting an intubated pediatric patient is probably the result of ___________?
Main stem intubation
Infants may be difficult to intubate because they have a more anterior larynx, relatively large tongues, and a floppy epiglottis.
The narrowest part of the larynx is below the vocal
cords at the _______
Cricoid cartilage
Best first step in treating a pulmonary hypertensive event?
Hyperventilation with 100% oxygen
If a child with tetralogy of Fallot has a hypercyanotic spell during induction of anesthesia, _____________, can reverse the right-to-left shunt
while pharmacologic treatments are being prepared.
Gentle external compression of the abdominal aorta
Read
In preeclampsia hypertension should be treated, but blood pressure should NOT be normalized.
Spinal anesthesia may be preferable to general anesthesia when the preeclamptic patient does not have an existing epidural catheter or there is insufficient time because of nonreassuring fetal heart rate tracing.
Read
If a patient is pacemaker dependent, the interference by electrocautery may be interpreted by the device as intrinsic cardiac activity, leading to profound inhibition of pacing and possible asystole. Devices should be programmed to the asynchronous mode before
surgery.
______ blood is the universal donor for packed red blood cells; for plasma it is ______.
O-negative blood
AB positive
Always reassess optimal positioning of any lung-isolation device after repositioning the patient. A malpositioned tube is suggested by (2)
- acute increases in ventilatory pressures
2. decreases in oxygen saturation
Methods to improve oxygenation during one-lung ventilation include (5)
- increasing FiO2
- adding PEEP to the dependent lung
- adding continuous positive airway pressure to the
nondependent lung - adjusting tidal volumes
- clamping the blood supply to the nonventilated lung
If PaCO2 significantly increases after 30 minutes of pneumoperitoneum, search for another
cause of hypercapnia such as
- capnothorax
- subcutaneous PaCO2
- CO2 embolism
- endobronchial intubation
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ should be considered the drug of choice for the induction of anesthesia for electroconvulsive therapy (ECT).
Methohexital
What kind of pain is usually less responsive to opioids than pain originating from nociceptors?
Neuropathic pain
Indirect-acting sympthomimetics (e.g., ephedrine) depend on ___________release to be effective.
Norepinephrine
Preganglionic sympathetic neurons originate from the _________ of the thoracolumbar spinal cord. These myelinated fibers exit via the _______ and synapse with postganglionic fibers in ____________, ____________, or a ________. Preganglionic neurons may ascend or descend the sympathetic chain before synapsing. Preganglionic neurons stimulate nicotinic cholinergic postganglionic neurons by releasing ______. Postganglionic adrenergic neurons synapse
at targeted end-organs and release __________
Intermediolateral columns
Ventral root of the spinal nerve
Paravertebral sympathetic ganglia, unpaired
prevertebral ganglia, or a terminal ganglion.
Acetylcholine
Norepinephrine
What are the 3 postganglionic receptors of the sympathetic nervous system? (3)
What is the preganglionic receptor of the sympathetic nervous system? (1)
a1, a2, B2
a2
Dopamine receptors are post or preganglionic?
Postganglionic
Preganglionic parasympathetic neurons originate from cranial nerves (4) and sacral segments ____.
III, VII, IX, and X (1973)
2-4
Are hydroxy-substituted phenylethylamines and stimulate adrenergic nerve endings.
Catecholamines
3 naturally occurring catecholamines
Norepinephrine, epinephrine, and dopamine
2 synthetic catecholamines
Dobutamine and isoproterenol
Synthesis of dopamine, norepinephrine, and epinephrine:
The amino acid _______ is actively transported into the adrenergic presynaptic nerve terminal cytoplasm, where it is converted to _____by two enzymatic reactions: (2)
Dopamine is transported into storage vesicles, where it is hydroxylated by ___________ to norepinephrine.
Epinephrine is synthesized in the ________ from norepinephrine through methylation by _______.
Tyrosine
Dopamine
- Hydroxylation of tyrosine by tyrosine hydroxylase to dopamine
- Decarboxylation of dopamine by aromatic L-amino acid decarboxylase.
Dopamine b-hydroxylase
Adrenal medulla
Phenylethanolamine N-methyltransferase
How is norepinephrine metabolized?
Norepinephrine is removed from the synaptic junction by ______ into the presynaptic nerve terminal and __________.
Reuptake
Metabolic breakdown
The enzyme ____________ metabolizes norepinephrine within the neuronal cytoplasm.
Both ______ and _____ metabolize the neurotransmitter at extraneuronal sites.
The important metabolites are (3)
Monoamine oxidase (MAO)
MAO and catecholamine O–methyltransferase (COMT)
- 3-methoxy-4-hydroxymandelic acid
- metanephrine
- Normetanephrine.
The cholinergic neurotransmitter acetylcholine (ACh) is synthesized within presynaptic neuronal
_______by esterification of _____ and ____by the enzyme _______; it is stored in synaptic vesicles until release.
After release, ACh is principally metabolized by acetylcholinesterase, a membrane-bound enzyme located in the synaptic junction. Acetylcholinesterase is also located in other nonneuronal tissues such as _____.
Mitochondria Acetyl coenzyme A Choline Choline acetyltransferase Erythrocytes
Phenylephrine stimulates primarily ____ receptors, resulting in increased systemic vascular resistance and blood pressure.
A1
Ephedrine produces norepinephrine release, stimulating mostly ___ and ___ receptors; the effects resemble those of epinephrine although they are less intense.
A1 and B1
What beta blocker has an a-blocking property?
Labetalol
Closing capacity increases with age and is equal to FRC in the supine individual at approximately ___ years and in the upright individual at approximately ___ years.
44
66
What represents the amount of base (or acid) needed to titrate a serum pH back to normal at 37 C while the PaCO2 is held constant at 40 mm Hg.
BD (or base excess)
Compartment model (%):
Solids?
Fluids?
ICF?
ECF?
ISF (interstitial)?
BV (blood vol)?Solids 43%
Fluids: 57%
ICF: 35%
ISF: 15%
BV: 7%
What hormone body water and tonicity regulated?
Half life?
AHD
20 mins
Hypothalamic osmoreceptors have an osmotic threshold of about ____ mOsm/kg. Above this level ADH release is stimulated.
289
Hypothalamic thirst center neurons regulate conscious desire for water and are activated by an increase in plasma sodium of ___ mEq/L, an increase in plasma osmolality of ___ mOsm/L, and loss of potassium from
thirst center neurons and angiotensin II.
2
4
ADH, or vasopressin, is synthesized in the _____ and ______ nuclei of the hypothalamus.
supraoptic
paraventricular
Where is angiotensinogen produced?
liver
What is the normal range for serum osmolality?
285 and 305 mOsm/L
The most common cause of postoperative hyponatremia is (2)?
SIADH
Water retention
Generally elective surgery should be delayed if serum sodium levels exceed mEq/L?
150
Hyperkalemia >__ mEq/L should be corrected before elective procedures. Usually ____ is the treatment.
6
Dialysis
Changes in stored blood that reduce post-transfusion viability are known as?
Storage lesions
Mild hypothermia (34 to 36 C) increases blood loss by ___ % and increases the relative risk for transfusion by ____ %.
16%
22%
Erythropoietin stimulates erythrocyte production in ___ to ___ days
5 to 7
When a clot is formed, plasminogen is incorporated and then converted to plasmin by tissue plasminogen activator (tPA) and fragments of factor ____.
XII
It is a potent vasodilator that inhibits platelet activation and helps confine primary hemostasis to the injured area.
Prostacyclin (PGI2)
Antithrombin III complexes with and deactivates
circulating coagulation factors (except factor ____).
VIIa
Protein C inactivates factors (2)
Va and VIIIa
In von Willebrand’s disease there is a decrease of both factor ___ antigen and factor VIII:vWF.
VIII & VIII:vWF
Coagulation is initiated primarily by contact of factor ___ with extravascular tissue.
VII
The most common intraoperative bleeding diathesis is ?
Dilutional thrombocytopenia
_____ is a dynamic test of clotting and can be as useful as all other clotting tests combined.
Thromboelastography
The extrinsic pathway is affected first by vitamin K
deficiency because the factor with the shortest half-life is factor ____, found only in the extrinsic pathway.
VII
What is a polyanionic mucopolysaccharide that accelerates the interaction between antithrombin III and the activated forms of factors II, X, XI, XII, and XIII, effectively neutralizing each?
Heparin
What is the phospholipid surface in the
- Intrinsic pathway?
- Extrinsic pathway?
- Platelet phospholipid
2. Tissue thromboplastin
What does the partial thromboplastin time measure?
Intrinsic and common pathways except factor XIII
What does the prothrombin time measure?
Extrinsic and common pathways
Cryoprecipitate contents (4)
- VIII
- XIII
- vWF
- fibrinogen
What nerve blocks are useful when awake intubation is planned?
Glossopharyngeal nerve
Superior laryngeal nerv
Is most accurate for determining FRC in patients with obstructive airway disease.
Plethysmography
What law states that the volume of gas in a closed space varies inversely with the pressure to which it is subjected.
Boyle’s law
Measures the rate of uptake of the nonphysiologic gas carbon monoxide (CO).
Diffusing capacity for the single-breath diffusion capacity (DLCO)
Upper abdominal procedures result in a decrease in FRC within _________; FRC gradually returns to normal by _______.
10 to 16 hours
7 to 10 days
The potency of anesthetic gases is compared using?
Minimal alveolar concentration (MAC)
What is the term for the concentration required to block autonomic reflexes to nociceptive stimuli?
What is its value?
MAC-BAR
1.7-2
What is the term for the concentration required to block appropriate voluntary reflexes and measure perceptive awareness?
What is its value?
MAC-awake
0.3 to 0.5 MAC
The highest MACs are found in what age group of patients?
Infants at 6 to 12 months of age
For every Celsius degree drop in body temperature, MAC decreases approximately how many percentage? (range)
2-5%
Describes the distribution of a given agent at equilibrium between two substances at the same temperature, pressure, and volume
Partition coefficient
Ultimately is the principal factor in determining onset of action of volatile anesthetics?
Alveolar concentration
What theory observed that observed that an increasing
oil-to-gas partition coefficient correlated with anesthetic potency.
Meyer-Overton lipid solubility theory
______ and _______ found that an amphophilic solvent (octanol) correlated better with potency than lipophilicity and concluded that the anesthetic site must contain both polar and nonpolar sites.
Franks and Lieb
When nitrous oxide is discontinued abruptly, its rapid diffusion from the blood to the alveolus decreases the oxygen tension in the lung, leading to a brief period of
decreased oxygen concentration known as?
Diffusion hypoxia
Read
Speed of onset of volatile anesthetics is increased by increasing the delivered concentration of anesthetic, increasing the fresh gas flow, increasing alveolar ventilation, and using nonlipid-soluble anesthetics.
Read
MAC is decreased by old age or prematurity, hyponatremia, hypothermia, opioids, barbiturates, a2-blockers, calcium channel blockers, acute alcohol intoxication, and pregnancy.
MAC is increased by hyperthermia, chronic alcoholism, and CNS stimulants (e.g., cocaine).
Degradation of _____ and _______by desiccated absorbents may lead to CO production and poisoning.
- Desflurane
Sevoflurane
Toxicity to this volatile anesthetic toxicity is a rare but real threat in abusers, patients with vitamin B12 deficiencies, and possibly unborn fetuses because of impaired methionine synthesis and results in neurologic sequelae.
Nitrous oxide
Which anesthetic agent is most associated with cardiac dysrhythmias?
Halothane
Fluoride-associated renal dysfunction has been linked to the use of what volatile anesthetic?
Methoxyflurane
What volatile anesthetic administered to pregnant rats in concentrations greater than 50% for over 24 hours has been shown to increase skeletal abnormalities?
Nitrous oxide
Is a mu-, k-, and s-receptor antagonist that will reverse the effects of agonist drugs.
Naloxone
The peak effect occurs within 1 to 2 minutes
Duration 30 to 60 minutes
Incremental doses of 0.5 to 1 mcg/kg should be used initially
As a k-receptor agonist, this drug may be used to suppress postoperative shivering. Notably is contraindicated for use in patients taking monoamine oxidase inhibitors because the combination may lead to serotonin toxicity, hyperthermia, and death.
Meperidine
Neuraxial opioids bind to receptors in ________ of the spinal cord.
Rexed lamina II (substantia gelatinosa) in the dorsal horn
Activation of m-receptors appears to reduce visceral and somatic pain via g-aminobutyric acid–mediated descending pain pathways. Activation of k-receptors appears to reduce visceral pain via inhibition of
substance P.
IV anesthetic with an imidazole derivative the induction properties of which result from Gammaamino-butyric acid (GABA) receptor modulation. It is noted for its hemodynamic stability.
Etomidate
What happens when you inject sodium thiopental intra-arterially?
Intra-arterial STP is likely to cause significant discomfort, vasospasm, and possibly thrombus formation. Leave the catheter in place and inject dilute papaverine, procaine, or lidocaine through the catheter to inhibit smooth muscle vasospasm. If this does not re-establish perfusion, consider brachial plexus block or a-blockade. Also administer heparin to prevent
thrombus formation.
The GABA receptor complex is composed of two a-subunits and two b-subunits. Where does the benzodiazepine bind to?
a-subunit
The GABA receptor complex is composed of two a-subunits and two b-subunits. Where does the benzodiazepine bind to?
a-subunit
Prolonged exposure of the receptors to SCH results in persistent open receptor channel and ionic fluxes through the ion pore, known as __________. Normal depolarization/repolarization is not possible until SCH is metabolized.
phase II or desensitization blockade
How do mature and immature acetylcholine receptors differ?
Mature contains e-receptor
Immature contains y-receptor
Where is pseudocholinesterase produced?
Pseudocholinesterase is produced in the liver and circulates in the plasma.
Example of aminosteroid relaxants?
“curonium”
pancuronium, vecuronium, pipecuronium, and rocuronium
Relaxant with biliary excretion (2)
Vecuronium and rocuronium
Relaxant with Hoffman elimination (1)
Atracurium
Relaxant metabolized by pseudocholinesterase.
Mivacurium
Relaxant with tachycardic side effect
Pancuronium
Discuss important characteristics of a nerve stimulator. (3)
- Single twitch at 0,1 Hz
- TOF of 2 Hz
- Tetanic stimulation at 50 Hz
Black electrode (-) depolarize
Red electrode (+) hyperpolarize
Which nerves can be chosen for stimulation?
Ulnar nerve
Discuss the appropriate time to reverse neuromuscular blockade based on nerve stimulation.
Neuromuscular blockade can be reversed when there is at least one twitch with TOF stimulation
How are local anesthetics metabolized?
- Esters
- Amides
- hydrolysis by pseudocholinesterases (plasma)
2. enzymatic biotransformation (liver)
What determines local anesthetic potency?
The higher the solubility, the greater the potency.
Why are epinephrine and phenylephrine often added to local anesthetics? What cautions are advisable regarding the use of these drugs?
These drugs cause local tissue vasoconstriction, limiting uptake of the local anesthetic into the vasculature and thus prolonging its effects and reducing its toxic potential.
______ acts primarily on the arterial vasculature whereas _____ has its most prominent effect on venous capacitance vessels
Sodium nitroprusside
Nitroglycerin
Is a new third-generation CCB that is considered an ultrashort-acting arteriolar vasodilator.
Clevidipine
Is a pyridazinone-dinitrite and a member of a new class of pharmacologic agents, the “calcium sensitizers.” This drug acts to increase contractility without elevating intramyocardial calcium levels. This is achieved by stabilizing troponin C in an active form, thus providing inotropic support in similar fashion to other agents but with much lower intracellular calcium requirements.
Levosimendan
What is the only acetylcholinesterase inhibitor that crosses the blood-brain barrier and can be used to treat the central anticholinergic syndrome?
Physostigmine
Bronchociliary function improves within ___ to ____ of smoking cessation, and sputum volume decreases to normal levels within about _______.
1 to 2 days
2 weeks
A patient may be instructed to stop warfarin __ days before surgery
4
However, at room temperature N2O condenses into a
liquid at ___ psi.
747
N2O cylinder tank contains about ___ liters.
1600 L
Wall gas pressures are typically about ____ psig
55
Tank pressure is generally regulated by the first-stage regulator to ___ psig.
45
N2O condenses into a liquid at _____ psi
747
E-cylinders of N2O contain the equivalent of about ___ L of gas when full, whereas E-cylinders of O2 and air hold only about 600 L.
1600
What leads are most helpful when looking for a bundle-branch block?
V1, V6, 1 and 2 (wide QRS > 120 sec
A condition which there is an ST-segment depression that occurs in patients with an ST-elevation MI.
Reciprocal change
Not all patients with ST-elevation MI have reciprocal change, but when it is seen, it generally confirms the diagnosis of acute MI
Most pulse oximeters use wavelengths of ____ nm (red) and ___ nm (infrared).
660
940
Refers to the variation in ICP in accordance with intracranial volume.
Intracranial elastance or compliance
CBF increasing/decreasing ___ to ___ ml/100g/min with a 1-mm Hg change in PaCO2.
1 to 2
2 preferred intravenous induction agents because they reduce both CBF and CMRO2 in increased ICP.
2 drugs to be avoided
Thiopental and propofol
Ketamine and etomidate should be avoided because ketamine increases CBF and ICP and the propylene glycol formulation of etomidate may induce neurologic deficits in at-risk tissue.
Range of CPP to maintain in traumatic brain injury?
MAP?
60-80 mmHg
>90%
Myopathy characterized by an uncontrolled increase in skeletal muscle metabolism after exposure to a triggering agent.
Malignant hyperthermia
The earliest symptom is of MH is?
Unexplained tachycardia
Dantrolene management in MH
Administer dantrolene, 2 mg/kg; repeat every 5 minutes to a total dosage of 10 mg/kg if needed.
Dantrolene sodium inhibits calcium release via RyR1 antagonism.
The solution is prepared by mixing 20 mg of dantrolene with 3 g of mannitol in 60 ml of sterile water.
The gold standard for diagnosis of MH?
Caffeine-halothane contracture test (CHCT)
Is defined as jaw muscle tightness with limb muscle flaccidity following a dose of succinylcholine.
Masseter muscle rigidity (MMR)
A condition which presents with present with
generalized fatigue and weakness that worsens with repetitive muscular use and improves with rest.
Myasthenia gravis
This is an immune-mediated disease of the neuromuscular junction that frequently arises in the setting of malignancy, often small-cell carcinoma of the lung. As opposed to MG, weakness improves with motor activity, although frequently the improvement is transient.
Lambert-Eaton myasthenic syndrome
Acute idiopathic polyneuritis or __________ is currently the most frequent cause of generalized paralysis and usually presents with sudden onset of weakness or paralysis, typically in the legs, that spreads to the trunk, arms, and bulbar muscles over several days.
Guillain-Barre´ syndrome
Drugs avoided in Guillain-Barre´ syndrome (2)
Succinylcholine and pancuronium
The leading cause of death in chronic users of alcohol is?
Cardiac dysfunction
Which nutritional deficiencies are seen in chronic alcohol users?
thiamine & folic acid
Best inhalational agent for maintaining hepatic blood flow.
Isoflurane
The American Diabetes Association (ADA) 2008 Clinical Practice Recommendations recommend an A1C goal for nonpregnant adults in general of?
<7% (6% or lower is the nondiabetic A1C range)
Approximately ___ mcg of T3 and __ mcg of T4 are produced daily.
8
90
The most common cause of hypothyroidism is _____ of thyroid tissue in the treatment of hyperthyroidism, most commonly Graves’ disease.
Surgical or radioiodine ablation
This in large doses not only blocks hormone
production, but it also decreases the VASCULARITY and SIZE of the thyroid gland,
Iodine
Normally approximately __ to __ mg of cortisol per day is produced.
20 to 30
Also referred to as acute adrenocortical insufficiency, an ________ is caused by a relative lack of cortisol or other glucocorticoid in relation to a physiologic stress such as
surgery. It is a shock state characterized by refractory hypotension, hypovolemia, and
electrolyte disturbances.
Addisonian crisis
Neurogenic shock is noted in trauma affecting what vertebral level
T6
2 MC complication of burn injury
- Pneumonia 2. Respiratory failure
Rule of nines
Head and neck 9% UPPER EXT 9% each chest ant & post 9% each ABDOMEN 9% Lower back 9% LOWER EXT 18% Perineum 1%
