Tải bản đầy đủ

2016 advanced knowledge asessment

• Question 1:
• A patient with a known hypertrophic cardiomyopathy and
dynamic left ventricular outflow tract obstruction is intubated
for community-acquired pneumonia. Urine output is minimal,
with no response to a fluid bolus. The patient is tachycardic
with HR of 120/min and BP of 118/74 mm Hg. Which of the
following therapies is most appropriate as part of the


• Correct Answer: C
• Rationale

Therapy for hypertrophic cardiomyopathy is directed at the

dynamic left ventricular outflow tract obstruction. The
obstruction causes an increase in left ventricular systolic
pressure, which leads to a complex interplay of
abnormalities that decrease cardiac output. In the intensive
care setting, this condition often deteriorates with volume
depletion, and with the institution of inotropic agents. In
that circumstance, the infusion of fluids and the
discontinuation of inotropic agents is the initial therapy. A
beta-blocker should also be added; however, if hypotension
is present, a vasoconstrictor such as phenylephrine should
be administered first. Acute onset of atrial fibrillation may
result in severe hemodynamic compromise due to the loss
of atrial contractions. Prompt cardioversion should occur in
this circumstance.

• The first-line approach to the relief of symptoms
is to block the effects of catecholamines that
exacerbate the outflow tract obstruction, and to
slow that heart rate to enhance diastolic feeling.
Beta-blockers are generally the initial choice to
accomplish these goals. Verapamil, the calcium
channel blocker, can also be used. Sudden death
has been reported in patients with severe
pulmonary hypertension and severe outflow
obstruction who are given verapamil. This drug
should be given with caution in patients with this
combination of findings. Nitroglycerin would
decrease cardiac filling and is problematic.

• Question 2:

• A 5-day-old infant presents to the emergency
department with RR of 84/min, oxygen saturation of
88%, HR of 170/min, and BP of 55/20 mm Hg. Physical
examination findings are notable for severe retractions;
cool, mottled extremities with weak peripheral pulses;
and lethargy. After intubation, establishment of
peripheral IV access, and an initial bolus of 20 mL/kg of
normal saline, the patient has not improved. Laboratory
values are as follows: sodium, 144 mEq/L; potassium,
5.0 mEq/L; chloride, 105 mEq/L; carbon dioxide, 13
mEq/L; blood urea nitrogen, 35 mg/dL; creatinine, 1.2
mg/dL; glucose, 105 mg/dL; ionized calcium, 4.7 mg/dL;
lactate, 7 mmol/L.

In addition to providing broad-spectrum antibiotics
and fluid, the most appropriate next step in
resuscitation is:
A)Dopamine to start at 5 µg/kg/min
B)Prostaglandin infusion
D)Calcium gluconate, 100-mg/kg bolus
E)Cardiology consultation

• Correct Answer: B
• Rationale

Neonatal shock has a broad differential diagnosis. Infection,
congenital heart disease, arrhythmia, and inborn errors of
metabolism can all present with shock. Much as with pediatric
and adult shock patients, the initial minutes of the resuscitation
are spent establishing means to stabilize the patient and
supporting intravascular volume. For the neonate with evidence
of poor cardiac output, ductal dependent congenital heart
disease must be considered. Current recommendations include
the initiation of prostaglandin infusion to maintain ductal patency
until the diagnosis of congenital heart disease can be excluded. If
the patient does not improve with fluids and prostaglandins, a
dopamine infusion is the next step. While neonates are more
dependent on extracellular calcium for myocardial contractility
than adults, this child has a normal ionized calcium level and
would not benefit from higher levels. Pulmonary hypertension is
frequently seen in septic neonates and can be treated with
inhaled nitric oxide, but this is not the next appropriate step for
this patient.

• Question 3:
• Which of the following measures would result in an
immediate increase in right ventricular stroke volume?

• A)Exhalation during positive pressure ventilation

• B)Relief of inferior vena cava compression
• C)Relief of intra-abdominal pressure
• D)Sustained right lateral decubitus positioning
• E)Sustaining a Valsalva maneuver while sitting

• Correct Answer: A
• Rationale

It has long been recognized that positive airway pressure in
lung inflation can have distinct effects on heart loading
conditions and performance. Other direct and indirect
effects on the heart have been suspected as well. Sustained
increased intrathoracic pressure produces a net decrease in
venous return and a decrease in stroke volume and cardiac
output. This clinical effect needs to be differentiated from
the dynamic immediate effects of intrathoracic pressure
variations. Lung inflation with positive airway pressure may
have dynamic effects on myocardial contractile status that
can have rapid onset, even during a single breath.

Positive-pressure inspiration, inferior vena cava
constriction, and release of abdominal compression have
all been reported to decrease right ventricular (RV)
inflow. RV inflow is increased with positive pressure
expiration, the release of inspiratory hold, the
constriction of the inferior vena cava, and abdominal
compression. Decrease of the RV end flow during
positive pressure inspiration and vena cava constriction
transiently decreases RV end-diastolic volume and
increases the transseptal pressure gradient, causing the
septum to shift to the right.

With left ventricular (LV) end-diastolic volume, the result is no
change in the anterior/posterior diameter and a stroke volume
increase; when RV inflow increases, the opposite occurs.
Therefore, during the expiratory phase of mechanical ventilation,
and when the inspiratory hold and the inferior vena cava
constriction are released, or during abdominal compression, the
transseptal pressure gradient decreases, causing the septum to
shift to the left. LV end-diastolic pressure and stroke volume
decrease as a result.

Mechanical ventilation can affect cardiac function
through a number of mechanisms. Direct ventricular
interaction (change in the volume of one ventricle
causing a simultaneous and opposite change in the
volume of the other ventricle) is one of the mechanisms
by which positive end-expiratory pressure may decrease
the left ventricular end-diastolic volume in output during
mechanical ventilation. These effects are dependent on
the presence of pericardial constraint. A sudden decrease
in right ventricular end-diastolic volume is associated
with a simultaneous increase in left ventricular enddiastolic volume, whereas a sudden increase in right
ventricular end-diastolic volume is associated with a
decrease in left ventricular end-diastolic volume.

• Question 4:
• A 40-year-old man with hypertension is admitted to the ICU for
3 days with right leg swelling. He has also noted pain and a
bluish discoloration. The patient had a previous left-leg, belowthe-knee amputation due to a motor vehicle accident and
venous thrombosis of the left leg, with the placement of an
inferior vena cava filter. BP is 102/52 mm Hg, HR is 80/min, RR is
28/min, and temperature is 35.2°C (95.3°F). The right leg is
noted to be swollen to the inguinal ligament with bluish
discoloration most prominent in the ankle, foot, and distal thigh.
Femoral and pedal pulses are palpable but decreased.
Laboratory results include the following: WBCs, 23,500/µL;
hemoglobin, 16.4 g/dL; prothrombin time, 41.3 seconds;
activated partial thromboplastin time, 200 seconds; D-dimer,
positive; sodium, 139 mmol/L; potassium, 3.5 mmol/L;
bicarbonate, 16 mmol/L; chloride, 102 mmol/L; glucose, 107
mg/dL; blood urea nitrogen, 26 mg/dL; and creatinine, 4.1

Which of the following is the most important
the apeuti i te e tio fo this patie t’s o ditio ?
A)Catheter-directed thrombolysis
B)Operative venous thrombectomy
C)Right leg above-knee amputation
D)Broad-spectrum antimicrobials
E)IV heparin-based anticoagulation

• Correct Answer: A
• Rationale
This patient has phlegmasia cerulea dolens, an infrequent
but severe manifestation of venous thrombosis. This
condition can result in venous gangrene, arterial
compromise, loss of limb, and even death. The most
appropriate intervention to treat the underlying condition is
catheter-directed thrombolysis to rapidly remove the
thrombus and restore venous drainage. There are no welldesigned studies evaluating this approach, and it should be
reserved for limb salvage after an assessment of the riskbenefit ratio, as compared with routine anticoagulation.

Operative thrombectomy is an alternative intervention, but
because of its high mortality rate, it is usually used after the
failure of anticoagulation and thrombolytic therapy.
Although anticoagulation is indicated, heparin will not
alleviate the venous obstruction rapidly enough. While
amputation may be needed when other interventions fail, it
is reasonable to utilize other interventions to salvage the
limb prior to considering amputation. Although this patient
has an elevated white blood cell count and hypothermia,
these manifestations are most likely secondary to the tissue
ischemia and subsequent inflammatory response, rather
than an established infection. It is reasonable to obtain
culture data and consider antibiotic therapy, but these
interventions would not address the underlying cause. In
some case reports, phlegmasia cerulea dolens has been
associated with prior placement of inferior vena cava filters.
It may occur in lower as well as upper extremities.

With mild manifestations and subocclusive thrombosis,
systemic anticoagulation may be sufficient. With occlusive
thrombosis and vascular compromise, catheter-directed
thrombolysis would be the treatment of choice. In some
cases, catheter access to the thrombosis may be impossible
and a thrombectomy would be indicated. Fasciotomy may be
required after reestablishment of the flow and stabilization
of the patient to relieve the elevated compartment

• Question 5:
• A 36-year-old, gravida 1, para 1 woman is admitted to the
ICU for the diagnosis of severe preeclampsia with a
persistent BP of 165/112 mm Hg, 4+ proteinuria, and
decreased urinary output (< 30 mL/h). Which of the
following is the best initial agent for controlling her




• Correct Answer: E
• Rationale
Labetalol is the currently recommended drug of choice for
hypertension in the pregnant patient. All antihypertensive
agents can cross the placenta. Angiotensin receptor
blockers such as valsartan and angiotensin-converting
enzyme inhibitors such as enalapril are known to be
harmful to the fetus and should not be used whenever
possible. Nitroprusside has the potential to develop toxic
metabolites over time and with high doses and should not
be the initial agent selected absent a life-threatening
malignant hypertensive crisis. Furosemide can be used for
management of hypertension and is thought to be safe for
the fetus.

The risk in using a diuretic in a pregnant patient is
volume depletion; for this reason, furosemide
should be used with caution. Labetalol can be
used in the pregnant patient and, since it has
both alpha-adrenergic and beta-adrenergic
blocking properties, it may preserve placental
blood flow better than other beta-blockers.
While not listed as a choice, calcium channel
blockers such as nifedipine have also been used
to manage hypertension in pregnancy, as has
magnesium sulfate.

• Question 6:
• The morning after an open cholecystectomy, a 49year-old woman develops nausea and vomiting. On
examination, her abdomen is tympanitic and
distended. She has diffuse mild pain with palpation.
Radiograph of the abdomen shows a normal gas
pattern in the small bowel and distended right and
transverse colon. Rectal enemas result in a slight
decrease in abdominal distension. However, the
patie t’s ausea a d o iti g pe sists. Afte se e al
doses of a a tie eti , the patie t’s h th st ip
shows QT prolongation and then torsade de pointes.
She is successfully resuscitated with magnesium

• Which of the following medications was most likely
used to treat her nausea and vomiting?


• Correct Answer: C
• Rationale
A number of drugs can lead to QT prolongation and torsade de
pointes. Droperidol, a butyrophenone derivative, is an
antiemetic that has the potential of prolonging the QT interval.
Fortunately, it rarely produces this phenomenon at
recommended doses. Antiemetics such as ondansetron
(serotonin antagonists), metoclopramide (antidopaminergic
and antiserotonergic), and dronabinol (cannabinoid derivative),
are not known to cause QT prolongation. Phenothiazines used
for nausea and vomiting may also cause QT prolongation but
are not among the answer choices. Targeted drug therapy for
nausea and vomiting can improve the success of relieving
symptoms. In addition, being aware of associated adverse drug
reactions can help decrease the drug-related complications
from the drug itself or through drug-drug interactions.

Postoperative nausea and vomiting are often
multifactorial in origin. Drugs, physical stimuli, or
emotional stress can cause the release of
neurotransmitters that stimulate serotonergic (5-HT3),
dopaminergic (D2), histaminergic (H1), and muscarinic (M1)
receptors. The receptor stimulation in the chemoreceptor
trigger zone, gastrointestinal tract, vestibular apparatus,
pharynx, or cerebral cortex triggers neurogenic signals to
be sent to the vomiting center in the brainstem. The
vomiting center, rather than a discrete area, is more of a
neural network comprising the chemoreceptor trigger
zone, area postrema, and nucleus tractus solitarius.

Vagal afferent signals through the nodose ganglion
and the nucleus tractus solitarius mediate nausea
that arises from gastric irritants; gastric, small
intestinal, colonic, or bile duct distension; and
inflammation or ischemia of bowel, liver, pancreas,
and peritoneum.

Phenothiazines and butyrophenones act on D2, H1,
and M1 receptors. Benzamides, such as
metoclopramide and domperidone, affect 5-HT3 and
5-HT4 receptors; scopolamine is an M1-receptor
antagonist; and diphenhydramine and cyclizine are
H1 antagonists. Specific 5-HT3-receptor antagonists,
such as ondansetron and granisetron, are the most
recently developed class of antiemetics.

Tài liệu bạn tìm kiếm đã sẵn sàng tải về

Tải bản đầy đủ ngay