ACE 9A Flashcards
(136 cards)
1
Q
What age group is at greatest risk for developing PDPH?
A
Patients age 20 to 40.
2
Q
Where does the dural sac terminate in infants?
A
As low as S3
(which means that intrathecal injection during a caudal which is typically done at level S4-S5 is a possible complication)
3
Q
How does total spinal block initially present in an infant?
A
Apnea, immobility WITHOUT initial change in HR or BP.
The hemodynamic stability is proposed to occur due to the relatively low sympathetic tone present in an infant compared with that in an adult. Bradycardia can develop but would most likely be delayed and assocaited with the development of hypoxemia.
4
Q
Point out the findings and make the diagnosis.
A
Evolving inferoposterolateral infarction (STEMI).
- the prominent Q waves in II, III, and aVF, along with ST elevation and T wave inversion in these leads, as well as V3 through V6.
- ST depression in I, aVL, V1, and V2 is consistent with a reciprocal change.
- Relatively tall R waves are also present in V1 and V2.
5
Q
In the event percutanous intervention is unavailable to treat an acute STEMI, what should the next-line intervention be?
A
Thrombolytic therapy, if appropriate.
Coronary bypass is not recommended in the setting of an acute STEMI and may even be harmful.
6
Q
Make the diagnosis and describe the findings.
A
Mitral stenosis
Transesophageal echocardiogram 2-dimensional midesophageal view of mitral stenosis. Mitral valve (MV) with minimal opening during diastole. Flow acceleration of color Doppler indicates significant left atrium (LA) to left ventricular (LV) gradient. This patient requires a prolonged diastolic phase for adequate LV filling and ultimately cardiac output.
7
Q
How does mitral stenosis affect PAOP?
A
PAOP will be overestimated.
8
Q
Define rheobase.
A
the minimum current intensity necessary to depolarize a nerve
9
Q
Define chronaxie
A
the minimum duration of the electrical stimulus when the intensity is twice the rheobase
10
Q
Why is it that a nerve stimulator can elicit a motor response without inducing pain or paresthesia? (Give the answer in terms of chronaxie and rheobase).
A
The ability to elicit a motor response without inducing pain or paresthesia is due to the fact that the chronaxy in motor nerves (A-alpha fibers) is lower than that of sensory nerves (A-delta and C fibers).
11
Q
What does the phrase accomodation of an electrical stimulus mean in the context of nerve-stimulation guided regional techniques?
A
Accommodation occurs when a subthreshold stimulus inactivates sodium conductance before stimulation threshold is achieved. This may result in the inability of a properly positioned needle to stimulate the nerve fiber. A square wave stimulus is used to minimize the likelihood of accommodation.
12
Q
Which electrode (cathode or anode) will more easily elicit a motor response?
A
Cathode
Using the cathode requires significantly less current to elicit a motor response.
13
Q
How does insulation of an peripheral nerve electric stimulating needle change the properties of the needle?
A
Insulation of the stimulating needle focuses the current density at the tip of the needle. This results in the ability to use a lower current to stimulate the nerve.
Use of an uninsulated needle has been demonstrated to produce a motor response even when the tip of the needle is as much as 0.8 cm beyond the nerve.
14
Q
What is perhaps the most common physical finding in patients with SLE?
A
Pericarditis.
78% of all SLE patients have pericarditis.
Slightly over 50% of all SLE patients have asymptomatic pericarditis and roughly an additional 25% become symptomatic.
(Put another way, nearly 80% of SLE patient have pericarditis and of those, 1/3 will have symptoms of pericarditis)
15
Q
What are side effects of cyclophosphamide?
A
- myelosuppression
- inhibition of plasma cholinesterase
- cardiotoxicity
- leukopenia
- hemorrhagic cystitis
16
Q
What drugs commonly used for lupus-related sequelae can cause myelosuppression?
A
- Cyclophosphamide
- Azathioprine
- Methotrexate
17
Q
What are side effects of azathioprine?
A
- myelosuppression
- hepatotoxicity
18
Q
What are side effects of methotrexate?
A
- Myelosuppression
- Pulmonary infiltrates and fibrosis
- hepatic fibrosis/cirrhosis
19
Q
What are side effects of hydroxychloroquine?
A
- retinotoxicity
- neuromyotoxicity
- cardiotoxicity
20
Q
Name two thienopyridine drugs.
A
- Clopidogrel
- Ticlopidine
21
Q
What is the mechanism of action of clopidogrel and ticlopidine?
A
These two thienopyridine drugs inhibit ADP receptors on platelets.
22
Q
What is the mechanism of action of dipyridamole?
A
This antiplatelet agent inhibits the uptake of adenosine into platelets.
23
Q
What is the mechanism of action of aspirin’s antiplatelet activity?
A
Aspiring inhibits the conversion of arachidone acid to thromboxane A2 by cyclooxygenase 1.
24
Q
What is the mechanism of action of tirofiban?
A
Tirofiban is an antiplatelet drug that competitively inhibits glycoprotein IIb/IIIa receptors.
25
What is the mechanism of action of abciximab?
Abciximab is an antiplatelet medication that noncompetitively inhibits glycoprotein IIb/IIIa receptors.
26
What anesthetic agent has been shown to have teratogenic effects in humans at standard doses?
No currently used anesthetic agent has been shown to have teratogenic effects in humans when used in standard doses at any gestational age.
- 2009 Joint Statement of ASA and ACOG
The ACE answer continues to say: Overall, although no currently used anesthetic agent has been proved to have a teratogenic effect in humans when used in standard doses at any gestational age, it is prudent not to assume that no effect exists. Therefore, elective general anesthesia should be postponed until the second trimester after the critical periods of development have passed and regional anesthesia should be encouraged whenever appropriate.
27
In which trimester are perioperative preterm contractions and spontaneous abortions least likely to occur?
Second trimester
which is why nonurgent surgery if possible should be performed during the 2nd trimester
28
29
What is the mechanism of action of gabapentin?
Gabapentin binds the alpha-2-delta subunit of the L-type calcium channel and acts to stabilize the membrane. This is felt to be its major mechanism of action in the treatment of chronic pain.
Administration of gabapentin produces an increase of GABA in the brain. This is not thought to be the mechanism of its analgesic action.
30
Which enzyme marker used to diagnose myocardial infarction has the shortest duration (window of time in which it may be measured)?
Myoglobin (12hr - 24hrs)
31
In order from longest to shortest duration in plasma after a myocardial infarction, list the following cardiac enzymes:
LDH, CK-MB, Troponin, myoglobin
Troponin (7d-10d) \> LDH(6d-8d) \> CK-MB(1-2d) \> myoglobin(12hrs-24hrs)
32
What is the major risk of the disease pseudotumor cerebri?
Blindness (2/2 papilledema)
33
What is pseudotumor cerebri?
Pseudotumor cerebri is a clinical syndrome of increased intracranial pressure (ICP) in the absence of intracranial lesions.
34
What is risks are associated with neuraxial anesthesia in a patient with pseudotumor cerebri?
In addition to the risks that apply to everyone, there is a theoretical concern about placing large volumes of local anesthetic quickly into the epidural space in a patient who already has increased ICP.
Neuraxial anesthesia is not contraindicated in patients with idiopathic intracranial hypertension. Unlike an intracranial mass producing increased ICP, drainage of the lumbar CSF, which is the primary method of mechanical therapy, does not lead to uncal herniation.
35
Where is a retrobulbar block placed in comparison to a peribulbar block?
A retrobulbar block requires deposition of local anesthetic inside the musclar cone behind the eye which limits spread of the local anesthetic. Peribulbar blocks require more volume by comparison but are placed outside the medullary muscular cone.
36
How does one block the orbicularis oculi from blinking via each of the following blocks: retrobulbar block, the peribulbar block, sub-tenon block, and topical blocks?
Of these, the peribulbar block is the only one that also blocks the orbicularis oculi.
The rest would require an separate block of the facial nerve.
37
Which is safer peribulbar or retrobulbar blocks?
Peribulbar more than likely, although meta-analysis have yet to prove it. Given their equal efficacy, peribulbar is generally recommended and people are advocating the discontinuation of retrobulbar blocks.
38
In 2009, the ASA redefined various levels of sedation to replace the catch-all "conscious sedation". What is the definition of minimal sedation?
aka light sedation, aka anxiolysis
requires only verbal stimulation to elicit a response. The airway, spontaneous ventilation and cardiovascular function are unaffected. No special training is required beyond the normal scope of practice of the health care provider when providing minimal sedation.
39
In 2009, the ASA redefined various levels of sedation to replace the catch-all "conscious sedation". What is the definition of deep sedation?
Deep sedation requires a painful stimulus to elicit a purposeful response (eg, attempting to remove the source of the painful stimulus). Withdrawal from a painful stimulus is not considered a purposeful response. The patient may need assistance in maintaining airway patency. Cardiovascular function is usually maintained by the patient without intervention. Spontaneous ventilation may or may not be adequate.
40
In 2009, the ASA redefined various levels of sedation to replace the catch-all "conscious sedation". What is the definition of moderate sedation?
For moderate sedation, according to the ASA criteria, the patient must be able to respond purposefully to verbal or tactile stimulation and require no assistance to maintain a patent airway. Cardiovascular function is usually maintained by the patient without intervention. Spontaneous ventilation is adequate.
41
What level of sedation is the threshold for a requiring a practitioner trained and capable of rescuing the patient when necessary as defined by the ASA?
Moderate sedation and deeper.
42
Define pulsus paradoxus.
When there is a difference between systolic blood pressure during inspiration and expiration greater than 10 or 12 mm Hg (depending on the authors).
The term pulsus paradoxus is a misnomer. Under normal circumstances, there is a small decrease in systolic blood pressure during spontaneous inspiration. Pulsus paradoxus describes the situation when this change is exaggerated, not paradoxical (which would suggest an increase in systolic blood pressure during spontaneous inspiration).
43
* What cardiac etiology(ies) is (are) associated with pulsus paradoxus?
* Pericardial tamponade
* Heart failure
* Constrictive pericarditis
Although pulsus paradoxus is commonly considered as an indicator of pericardial tamponade, it is not pathognomonic for tamponade.
44
What pulmonary conditions can cause pulsus paradoxus?
* Emphysema
* Asthma
* Pneumothorax
* Pulmonary embolism
45
What common metabolic condition can cause pulsus paradoxus?
Obesity
46
Name four herbal remedies with digitalis-like effects that can cause hyperkalemia?
* hawthorn berries
* lily of the valley
* milkweed
* Siberian ginseng
47
What immunosuppressant drugs are associated with hyperkalemia?
* Cyclosporine
* Tacrolimus
48
What are the indications for the consumption of *Zea mays* and how can it affect electrolytes?
Also known as corn silk, Zea mays has diuretic properties and recommended to UTIs, kidney stones, and prostatitis.
It is reported to cause HYPOkalemia.
49
Where is angiotensinogen produced?
Liver
50
Where is renin produced?
Kidney
51
What triggers secretion of renin?
Decrease in renal perfusion, specifically the justaglomerular apparatus.
52
Where is aldosterone produced?
Adrenal gland cortex
53
What normally inhibits secretion of renin?
Perfusion of the juxtaglomerular apparatus increasing usually due to increased water and salt rention causing effective increases in circulating volume.
54
Where is angiotensin-converting enzyme produced?
Surface of pulmonary and renal endothelium.
55
Name 5 effects of angiotensin II.
1. Increased sympathetic activity
2. Increased H20 retention 2/2 tubular NaCl reabsorption and K excretion
3. Stimulates aldosterone secretion (augmenting #2 above)
4. Arteriolar vasoconstriction. Increase in BP.
5. Stimulates posterior lobe of pituitary to secrete ADH
56
What are the risk factors for postoperative apnea in an infant?
Postconceptual age \< 44 weeks (single-most important determinant)
gestational age at birth
anemia (defined as Hct \< 30)
57
What is the immediate goal of treating aspiration of gastric contents and via what method can it be achieved?
Maintaining adequate oxygenation with some level of PEEP.
58
If pure liquid (non-particulate matter) has been aspirated, is any suctioning recommended?
Tracheal suctioning with a large bore suction catheter is generally recommeneded but bronchial lavage is discouraged.
59
Should antibiotics be given empirically in the event of aspiration?
Probably not, unless grossly contaminated material (e.g. pond water) is aspirated.
Prophylactic antibiotics following aspiration of gastric contents has not been shown to improve outcome but is associated with increased incidence of VAP with drug-resistant organisms.
60
What is the most commone cause of noniatrogenic hypothyroidism in the US?
Autoimmune thyroiditis (aka Hashimoto thyroiditis)
61
Describe the cardiovascular changes in hypothyroidism.
Diminished function of beta-adrenergic receptors causing:
decreased inotropy
decreased chronotropy
increased SVR (due to letting alpha receptors "win")
62
Describe the blood pressure changes seen in hypothyroidism and why they occur.
Increase in diastolic pressure and decrease in pulse pressure due to increased SVR (because alpha receptors are unchecked in the setting of diminished beta-receptor activity)
There may also be hypotension due to decreased intravascular volume as a result of increased excretion of salt and water by the renin-angiotensin system in response to the BP changes above.
63
What ECG changes are associated with hypothyroidism?
Prolongation of the QT interval which can cause torsades that reportedly resolves completely with thyroid hormone replacement.
64
In what patients has thoracic epidural analgesia (TEA) been reported to decrease mortality?
Trauma patients with multiple rib fractures.
Thus TEA is highly recommended in these patients.
65
What postoperative outcomes can be improved with the use of thoracic epidural analgesia?
Overall, pulmonary complications are decreased.
Specifically decreased incidences of
* infection
* atelectasis
* hypoxemia
* duration of tracheal intubation and mech vent
66
What are the blood-gas partition coefficients for:
1. Isoflurane
2. Sevoflurane
3. Desflurane
4. Nitrous oxide
Isoflurane, 1.46
Sevoflurane, 0.65
Desflurane, 0.42
Nitrous oxide, 0.46
67
What three factors determine inhaled anesthetic uptake?
Solubility
cardiac output
alveolar-to-venous partial pressure difference
68
What is the formula for uptake of an inhaled anesthetic agent?
solubility x cardiac output x (Pa-Pv)
Pa-Pv = the alveolar-to-venous partial pressure difference
69
How are corticosteroids helpful in thyrotoxicosis?
They decrease the peripheral conversion of T4 to T3 and may be useful as antipyretic agents.
70
Why should aspirin be avoided in thyrotoxicosis?
ASA decreases protein binging, resulting in increased free T3 and T4 levels.
71
How should the hyperthermia of of thyrotoxicosis be treated?
Tylenol and cooling blankets
72
What is the mechanism of the thioamide antithyroid medications?
They inhibit thyroperoxidase thereby decreasing synthesis of T3 and T4
(Also, PTU can block peripheral conversion of T4 to T3 in large doses.)
73
Which of the betablockers may be best of that drug class for thyroid storm?
Propanolol
All beta-blockers decrease the sympathomimetic manifestations of thyroid storm but propranolol in particular inhibits the peripheral converstion of T4 to T3
74
What drug class inhibits thyroperoxidase?
The thioamide group inhibits thyroperoxidase.
(and thus, decrease synthesis of thyroid hormones T3 and T4)
75
Name three thioamide drugs.
* Methimazole
* Carbimazole
* Propylthiouracil
76
What drug should be given prior to the administration of iodine during thyrotoxicosis and why?
Thioamides should be given prior to iodine because iodine may stimulate synthesis of thyroid hormone.
77
What is the mechanism of action of iodine administration in thyrotoxicosis?
Prevents the release of thyroid hormones blocks T4 to T3 conversion.
(although it may stimulate synthesis of thyroid hormone as well which is why a thioamide medication should be started before giving it)
78
Name four drug classes used to treat thyrotoxicosis.
1) Beta-blockers
2) Thioamides
3) Iodides
4) Radioactive Iodine
79
If the radial artery becomes thrombosed as a result of cannulation, how long does it take for recanalization?
According to a 1973 of 20 patients, it took 75 days for all 20 patients to recanalize.
80
What are four risk factors for postoperative atrial fibrillation?
* age 60 or older
* preop tachycardia
* male gender
* reduced postop cardiac output
81
Which four conditions are the most frequently cited indications for using BiPAP to treat respiratory failure?
* Postop from thoracic or abdominal surgery
* Pulmonary edema due to decompensated CHF
* Acute exacerbation of COPD
* Immunosuppression (eg, organ transplantation)
82
What clinical findings are there in critical illness myopathy?
normal nerve conduction studies
increased serum CPK
absent compound muscle action potentials c/w a dx of unexcitable muscle
myosin filament loss with preservation of actin
83
What drugs are thought to be associated with critical illness myopathy?
steroids and NMBDs
84
What is the treatment of critical illness myopathy?
Entirely supportive and may include long-term mechanical ventilation to support weakness of the diaphragm and oropharyngeal muscles.
85
What is the Bezold-Jarsich reflex?
Characterized by bradycardia, peripheral vasodilation, hypotension.
86
Describe the Bainbridge reflex.
increase in heart rate due to a rise in central venous pressure.
This reflex is mediated by stretch receptors in the atria, carried by afferent impulses through the vagus to the spinal medulla.
87
Describe the oculo-cardiac reflex.
Occurs with traction on the extraocular muscles, surrounding tissues, or pressure on the globe itself. Stretch receptors send afferent impulses through the ciliary nerves, through the ophthalmic branch of the trigeminal nerve to the gasserian ganglion. The efferent pathway is via the vagus nerve. The resultant increase in parasympathetic tone causes a decrease in heart rate in 30% to 90% of patients undergoing ophthalmic surgical procedures.
88
What are the humoral effects of atrial stretch?
The atrial stretch reflex caused by atrial stretch receptors release atrial natriuretic factor. This hormon inhibits ADH and renin release in the kidney promoting diuresis and natriuresis.
89
What type of laser is a danger to both cornea and retina?
CO2 lasers
90
Rank desflurane, N2O, and sevoflurane in order of greatest to least effect on uterine tone.
Sevoflurane \> desflurane \>\> N2O
N2O has no effect on uterine tone. So it's a good thing to add if you're trying to maintain MAC but decrease the dose of a halogenated agent.
91
What uterotonic drug can counteract a volatile anesthetic's effect on uterine tone?
This effect cannot be eliminated by the use of uterotonic drugs such as oxytocin. Oxytocin-induced contractions decrease in frequency and strength in a dose-dependent fashion when volatile anesthetics are administered.
92
What is FRC by weight in healthy newborns and healthy adults?
30cc/kg in both.
93
What is the normal TLC in a neonate? In an adult?
(answer in terms of cc/kg)
Neonate 63cc/kg
Adult 82cc/kg
94
How does chest wall compliance in a neonate compare to that of an adult?
Chest wall compliance is increased in the neonate due to:
* Incomplete rib calcification
* high percentage of cartilage in chest wall
* undeveloped chest wall musculature
95
How does lung compliance in a neonate compare to that of an adult?
Neonatal lung compliance is less than that of an adult.
96
What is the laryngeal breaking phenomenon?
It occurs in all healthy neonates and is the termination of exhalation prior to getting to the relaxation volume.
(The relaxation volume is the volume that occurs at the balance point between lung compliance and chest wall compliance.) Basically what this means is that laryngeal breaking keeps the FRC in the neonate at 40% of TLC (or 30cc/kg), because if a neonate were to exhale all the way to the relaxation volume, then FRC would be only 10% of TLC.
This is yet another reason that an apneic infant quickly develops severe hypoxemia (because FRC is substantially less in that situation than it normally is).
97
What is tidal volume in a healthy newborn versus that of a healthy adult given by weight?
Newborn 6 - 8cc/kg
Adult 6 - 7cc/kg
98
What is O2 consumption in mL • kg–1 • min–1 for healthy newborns and adults?
Healthy newborn = 6 to 8 mL • kg–1 • min–1
Healthy adult = 3 to 4 mL • kg–1 • min–1
99
What is a type II statistical error?
false negative conclusion; failing to detect a difference when a true difference exists
100
How is methadone eliminated?
Biotransformation primarily by CYP450 3A4 and 2D6
101
What are two notable substances that inhibit CYP450 3A4?
Grapefruit and fluoroquinolones
102
What common drug class notably inhibits cytochrome P450 2D6?
SSRIs
103
What are the major side effects of inhaled quick-acting beta2-adrenergic agonists?
Hypokalemia
Hypomagnesemia
104
Why are inhaled quick-acting beta2-adrenergic agonists supposed to be used only as rescue drugs and not as routine schedule therapy?
Because paradoxical bronchospasm, severe enough to lead to death, has been reported with excessive use.
105
Name the two long-acting beta2-adrenergic agonists that are still on the market.
Salmeterol
Formoterol
106
How does the long-term use of salmeterol affect a patient's responsiveness to albuterol?
The response to short-acting beta2-adrenergic agonists is _not_ changed by the use of long-term beta2-adrenergic agonists.
107
What is the most effective therapy currently available to stabilize and reduce the symptoms of asthma?
Inhaled corticosteroids (eg, beclomethasone, budesonide, fluticasone, triamcinolone)
108
How much adrenal suppression do inhaled corticosteroids cause?
None. They have not been found to cause any.
109
What is symbicort?
A combination of budesonide (inhaled corticosteroid) and formoterol (long-acting beta2 agonist.
The FDA says that the combination is effective but carries a significant risk of paradoxical bronchospasm and death.
110
What is Advair?
A combination of fluticasone (an inhaled corticosteroid) and salmeterol (a long-acting beta2 agonist).
The FDA says that the combination is effective but carries a significant risk of paradoxical bronchospasm and death.
111
How long of a course of parenteral steroids does a patient need to be considered andrenal-suppressed and require steroid supplementation during stress?
2 weeks or oral or parenteral steroids in the previous 6 months.
112
What is ipratropium?
An anticholinergic bronchodilator which acts by blocking vagal-mediated bronchoconstriction.
113
What is combivent?
a combination of albuterol and ipratropium
114
What is a significant side effect of combivent?
Produces flu-like symptoms in 5 - 10% of patients.
115
What is the formula for calculating static compliance?
Cstatic = Vt / (Pplateau - PEEP)
116
What are typical findings in someone with lesions of the C7 nerve root?
pain or numbness that:
* radiates along the back of the shoulder,
* over the triceps,
* the dorolateral aspect of the forearm and
* over the dorsum of the middle and index fingers.
Weakness in triceps, latissumus dorsi, wrist flexors, finger extensors.
Diminished or absent triceps reflex.
117
What muscles are innervated by C5?
Deltoid (C5)
Biceps (C5 and C6).
118
What muscles are innervated by C6?
Biceps (along with C5)
Wrist extensors
119
What muscles are innervated by C7?
Wrist flexors
Finger extensors
120
What muscles are innervated by C8?
Finger flexors
121
What upper extremity muscles are innervated by T1?
Interossei
122
The biceps reflex tests the integrity of what spinal level?
C5 -6
123
The brachioradialis reflex tests the integrity of what spinal level?
C6
124
The triceps reflex tests the integrity of what spinal level?
C7
125
126
Where does pain manifest with C5 lesions?
Pain is typically referred to the shoulder girdle.
127
What findings are associated with a C6 lesion?
Pain and numbness in the thumb and middle fingers
Diminished biceps reflex
128
What is the distribution of pain due to a C8 lesion?
Pain in the medial arm and forearm radiating into the pinky and ring fingers.
129
What is normal PaCO2 in pregnancy?
30 - 32 mmHg
130
By how much in terms of percentage is MAC decreased during pregnancy?
25%
131
What hemoglobinopathy is associated with proliferative retinopathy?
Hgb SC (it is rare in HgbSS)
132
What is the typical baseline Hgb levels in HgbSS, HgbSC, and Arab phenotype?
6 - 9 g/dL in SS disease
higher than that in SC and Arab phenotype.
133
What infection can induce acute aplastic anemia in a patient with SS disease?
Parvovirus B19
134
What percentage of patients with sickle cell anemia suffer cholelithiasis, CRI, viral hepatitis, and peripheral neuropathy, respectively?
Cholelithiasis = 70%
CRI = 20%
Viral hepatitis = 10% (2/2 transfusions)
Peripheral neuropathy is very uncommon as a complication of SS disease.
135
What mutation causes sickle cell disease?
A single-point mutation: substitution of adenine with thymine on the beta-globin gene of chromosome 11. This leads to the placement of valine instead of glutamic acid in the sixth position from the end terminus of the beta-chain of Hgb.
136
What are the 4 main types of sickle cell crises?
Vascular occlusion
Hemolytic (sudden hemolysis)
Sequestration (sudden liver and spleen enlargement)
Aplastic (bone marros suppression)
