Emergency Med 3: AAA and Aortic Dissection Flashcards
Why are Abdominal Aortic Aneurysms so dangerous ?
Most are asymptomatic until rupture. A majority of patients who rupture will not make it to the hospital
Which demographics pose the greatest risk of AAA ?
Elderly
Males
Is AAA familial ?
Yes !
80% of patients with AAA have a first-degree relative with a history of aneurysm
What are risk factors involved with AAA ?
other aneurysms, hypertension, peripheral arterial disease, smoking, diabetes, and collagen vascular disease
Hallmark of aneurysm pathogenesis ?
Destruction of the medial layer of aorta
What molecules are drastically reduced in an aneurysmal aorta ?
Elastin and collagen
What happens to elastic fibers in a normal aorta going from proximal to distal ?
Elastin decreases –> more occurences of AAA distal to the renal arteries.
What diameter of AA is used as diagnostic for AAA ?
3 cm or more
How is LaPlaces Law applied in determining risk for AAA rupture ?
Wall tension = (pressure X radius)/tensile force
Thus the more dilated the AA gets the more tension will be on the wall and thus the greater chance of rupture occurring
Larger aneurysm will expand more quickly
What symptom occurs most often in patients with AAA ?
Abdominal pain (77%)
List symptoms often associated with AAA
Abdominal pain (77%)
Flank or back pain (60%)
Vomiting (25%)
Syncope (18%)
Hematemesis (5%)
Aneurysm has fistulized into the GI systemClassic History for AAA rupture
syncope without warning symptoms followed by severe abdominal/back pain or abdominal pain, hypotension, and a pulsatile abdominal mass
What is a common misdiagnosis for AAA and why ?
Kidney stones
Pain is often localized to unilateral flank.
(May also be seen in costovertebral angle, or in a single quadrant of the abdomen)
N/V are also commonly seen.
Hip pain, tenesmus, and urinary bladder symptoms have also been described in AAA. What is tenesumus ?
Feeling of needing to constantly defecate
On physical examination, what percentage of patients with AAA show a pulsatile mass ?
70 %
Other Clinical Features include :
Abdominal tenderness (41%)
Pain, Mass, Hypotension (30-40%)
Abdominal bruit (5-10%)
Absent lower extremity pulses (6%)
What does tenderness to palpation often indicate ?
rupture (however, non-tenderness does not indicate lack of tear.
periumbilical ecchymosis (Cullen’s sign) or flank ecchymosis (Grey-Turner’s sign) are indicative of ?
AAA rupture
How does GI bleeding occur in AAA rupture ?
Usually due to fistula to duodenum –> massive bleeding
At what size are AAA considered to be at significant risk of rupture ?
> 5cm
Common differential/misdiagnosis
Renal colic Pancreatitis Intestinal ischemia Diverticulitis Cholecystitis Appendicitis Perforated viscus Bowel obstruction Musculoskeletal back pain Acute MI
What are radiologic studies used for with suspected AAA ?
Confiramation (should not delay treatment however)
CT Scanning for AAA
Identifies 100% of AAA and > 95% of rupture
Can demonstrate the anatomic details of the aneurysm
Should only be used in stable patients
Can make alternative diagnoses
Which imaging modality is preferred for unstable patients ?
Ultrasound
Almost 100% sensitivity for demonstrating the presence of an aneurysm and measuring its diameter
What are some difficulties in using US for diagnosis ?
Rupture cannot be reliably seen (4%)
Technically difficult in the obese patient
Operator dependent
Is angiography useful for emergent AAA ?
Nope
Angiography can miss AAA with mural thrombus
Time consuming in the unstable patient
What are Labs that should be run in suspected AAA ?
Baseline laboratory studies, including CBC, BMP, and coags
EKG, PCXR, and type & cross for 4-6 units of PRBCs should be obtained
What are the standard resuscitative measures
for a patient with AAA rupture ? What must you be careful not to do ?
Two large-bore IVs
Cardiac monitor
Supplemental oxygen
GIve the patient too much fluid
Usually a systolic of 90 is fine.(permissive
hypotension)
Try not to use femoral lines if you can help it.
What must you be sure to transfuse early in AAA rupture ?
blood !
What must be done as soon as diagnosis of AAA rupture is suspected ?
Surgical consult and transfer to OR
50% mortality in patients with AAA rupture
When is endovascular repair preferred to operative repair ?
patients with diabetes COPD etc since they are not good candidates for surgery
What are the two populations that typically experience aortic dissection
- Young people with predisposing conditions such as Marfans and Ehlers Danlos
- People over the age of 50
Risk factors for Aortic Dissection ?
hypertension (66%), congenital heart disease, connective tissue disease, and pregnancy
(Atherosclerosis is rarely involved)
Iatrogenic Aortic Dissection
heart catherterization or cardiac surgery
In Aortic dissection, where does the blood tend to move between which two layers of the vasculature ?
Intima and adventitia (in the media)
Type A Aortic Dissection (Stanford)
a dissection that involves any portion of the ascending aorta
Occurs in approximately two-thirds of patients with aortic dissections
Type B Aortic Dissection (Stanford)
dissections that are restricted to the descending aorta
Debakey Type I and II are classified as Stanford Type A: T or F ?
True
Type I: dissections that involve the ascending aorta, the arch, and the descending aorta
Type II: involves the ascending aorta only
Debakey Type III dissections are classified at Stanford Type B. T or F ?
T
Type III: involves the descending aorta distal to the left subclavian artery only
What are the three main symptoms found in Aortic Dissection
Chest or back pain (88%)
Aortic regurgitation +/- CHF (50%)
Transitory pulse deficits (50%)
Are most patients with Aortic Dissection hypotensive or hypertensive ?
Most are hypertensive, but nearly 20% will show hypotension
When does hypotension during Aortic dissection occur ?
Dissection of Coronary arteries
Pericardial tamponade
Pain in the anterior chest is often associated with dissection where ?
Ascending aorta
Pain in the back is associated with dissection where ?
descending aorta
decreased pulsation in patients with aortic dissection can be sensed where ?
radial, femoral or carotid arteries
End organ manifestations associated with dissection
MI If coronaries are dissected. Pericardial disease Pulmonary disorders Stroke Musculoskeletal disorders Spinal cord injuries Intra-abdominal disorders
What is the most prevalent finding on chest X-ray ?
Widened mediastinum (75%)
Other Findings of CXR:
Aortic knob abnormalities (66%)
Calcification > 5 mm from the edge of the knob (calcium sign) or obliteration of the knob
Irregular aortic contour (38%)
Left pleural effusion (27%)
Deviation of the trachea, mainstem bronchi, or esophagus (NG tube) may also be seen
What cant CT show that may be helpful in treatment ?
Reliable Anatomic detail or aortic valve competence
What are the sensitivity and specificity involved with echocardiogram ?
95-100%
90-97%
What is the gold standard for diagnosing Aortic dissection ? Why is it not often the most used ?
Angiography
Time is of the essence and most diagnoses can be made with carful HnP and Radiograph
Unlike in AAA what must be done before operative care of an Aortic dissection ?
RADIOGRAPHIC CONFIRMATION !
What is treatment goal for BP and HR in AD ?
Systolic between 100-120 with a HR of 60-80
Which Beta Blockers are often given to control BP in AD ?
Beta blockers
Esmolol:
infusion of 500 mcg/kg over 1 minute followed by an infusion of 50-150 mcg/kg/minute
Metoprolol:
May be given IV in three, 5 mg doses every two minutes followed by 2-5 mg/h
Labetolol:
Given 0.25 mg/kg IV, then doubled every 15 minutes for desired effect or a total dose of 300 mg can be given 10-20 at a time
After BB’s are given what else can be given to help lower blood pressure ?
Sodium Nitroprusside ( give BB’s first to lessen the chance of reflex tachycardia)
Nitroprusside may be infused IV at 0.3-10 mcg/kg/min
What can be given to control patient pain ?
Narcotics (didn’t really need to make this card, whatevss)
In a dissection involving the ascending aorta, prompt surgical repair is required. When is this action contraindicated ?
The only contraindication is a simultaneous occurrence of a progressing stroke
How are most descending aortic dissections handled ?
Medically rather than surgically
Patients with dissecting aneurysms that only involve the descending aorta are worse surgical risks, and indications for repair are controversial
