ACE 9A Flashcards
What age group is at greatest risk for developing PDPH?
Patients age 20 to 40.
Where does the dural sac terminate in infants?
As low as S3
(which means that intrathecal injection during a caudal which is typically done at level S4-S5 is a possible complication)
How does total spinal block initially present in an infant?
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.
Point out the findings and make the diagnosis.
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.
In the event percutanous intervention is unavailable to treat an acute STEMI, what should the next-line intervention be?
Thrombolytic therapy, if appropriate.
Coronary bypass is not recommended in the setting of an acute STEMI and may even be harmful.
Make the diagnosis and describe the findings.
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.
How does mitral stenosis affect PAOP?
PAOP will be overestimated.
Define rheobase.
the minimum current intensity necessary to depolarize a nerve
Define chronaxie
the minimum duration of the electrical stimulus when the intensity is twice the rheobase
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).
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).
What does the phrase accomodation of an electrical stimulus mean in the context of nerve-stimulation guided regional techniques?
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.
Which electrode (cathode or anode) will more easily elicit a motor response?
Cathode
Using the cathode requires significantly less current to elicit a motor response.
How does insulation of an peripheral nerve electric stimulating needle change the properties of the needle?
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.
What is perhaps the most common physical finding in patients with SLE?
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)
What are side effects of cyclophosphamide?
- myelosuppression
- inhibition of plasma cholinesterase
- cardiotoxicity
- leukopenia
- hemorrhagic cystitis
What drugs commonly used for lupus-related sequelae can cause myelosuppression?
- Cyclophosphamide
- Azathioprine
- Methotrexate
What are side effects of azathioprine?
- myelosuppression
- hepatotoxicity
What are side effects of methotrexate?
- Myelosuppression
- Pulmonary infiltrates and fibrosis
- hepatic fibrosis/cirrhosis
What are side effects of hydroxychloroquine?
- retinotoxicity
- neuromyotoxicity
- cardiotoxicity
Name two thienopyridine drugs.
- Clopidogrel
- Ticlopidine
What is the mechanism of action of clopidogrel and ticlopidine?
These two thienopyridine drugs inhibit ADP receptors on platelets.
What is the mechanism of action of dipyridamole?
This antiplatelet agent inhibits the uptake of adenosine into platelets.
What is the mechanism of action of aspirin’s antiplatelet activity?
Aspiring inhibits the conversion of arachidone acid to thromboxane A2 by cyclooxygenase 1.
What is the mechanism of action of tirofiban?
Tirofiban is an antiplatelet drug that competitively inhibits glycoprotein IIb/IIIa receptors.
What is the mechanism of action of abciximab?
Abciximab is an antiplatelet medication that noncompetitively inhibits glycoprotein IIb/IIIa receptors.
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.
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
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.
Which enzyme marker used to diagnose myocardial infarction has the shortest duration (window of time in which it may be measured)?
Myoglobin (12hr - 24hrs)
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)
What is the major risk of the disease pseudotumor cerebri?
Blindness (2/2 papilledema)
What is pseudotumor cerebri?
Pseudotumor cerebri is a clinical syndrome of increased intracranial pressure (ICP) in the absence of intracranial lesions.
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.
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.
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.
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.
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.
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.
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.
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.
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).
- 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.
What pulmonary conditions can cause pulsus paradoxus?
- Emphysema
- Asthma
- Pneumothorax
- Pulmonary embolism
What common metabolic condition can cause pulsus paradoxus?
Obesity
Name four herbal remedies with digitalis-like effects that can cause hyperkalemia?
- hawthorn berries
- lily of the valley
- milkweed
- Siberian ginseng
What immunosuppressant drugs are associated with hyperkalemia?
- Cyclosporine
- Tacrolimus
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.
Where is angiotensinogen produced?
Liver
Where is renin produced?
Kidney
What triggers secretion of renin?
Decrease in renal perfusion, specifically the justaglomerular apparatus.
Where is aldosterone produced?
Adrenal gland cortex
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.
Where is angiotensin-converting enzyme produced?
Surface of pulmonary and renal endothelium.
