EBM Session 3 Flashcards
(26 cards)
what are the image modalities of the heart that you might order on a patient undergoing surgery?
Start with a transthoracic ecco.
If there is too much scarring present or a collapsed lung move onto the transesophageal ecchocardiogram.
What are alternative angiograms that can be offered to those whom are allergic to iodine contrast or have impaired renal function?
CO2 angiograms used at the level of the diaphragm.
What is the difference between positive and negative contrast angiograms?
Positive contrast angiograms make the structures appear denser than surrounding tissue by making structures less permeable to X-ray. ACHIEVED BY DYE SUCH AS IODINE.
Negative contrast makes structures appear darker than surrounding tissue by making structures more permeable to X-ray. ACHIEVED BY GAS LIKE CO2
Define Sequestrum:
Dead necrotic bone that acts as a foreign body in osteomyelitis.
Define Involucrum:
Chronic process where new bone is laid down around the dead bone.
Define: Cloaca
Opening along the cortex where pus drains out in osteomyelitis.
Define rarefraction:
Localized bone density loss (30-40% mineralized loss to see on x-ray)
This is seen in ostemyelitis.
Define: Hematogenous Osteomyelitis
Caused by bacteria that spread through the bloodstream instead of the normal cancellous bone route.
Most commonly see in children within the metaphysis.
In adults it is found within the metatarsal heads.
Define: Direct extension osteomyelitis
Secondary to a traumatic injury or surgery in which the periosteum is infected and it slowly migrates through the sharpey fibers to the cancellous bone.
Think about patients that have persistant cellulitis even with abx treatment.
Define: contiguous osteomyelitis
Commonly found in chronic ulcers in which the spread of infection is from the soft tissue into the underlying bone.
MOST COMMONLY STAPH AUREUS. (GBS in infants)
What are the three main modalities of osteo testing?
Tech 99 bone scan (renal excretion) Will see in the third phase (bone phase) at 4 hours.
CT: Excellent for articular/periarticular evaluation.
Ceretex (99mTC-HMPAO) labeled leukocyte scan for active infection.
What is the dosage and coverage of Cephazolin?
First generation cephalosporin used for community acquired infections and surgical prophylaxis.
Dose is 1g q8h IM or IV
Step up: 2g q8h for severe
Excellent choice over nafcillin for the longer half life.
Cephalexin (keflex/keftab) and cephradine (Velosef) dosage and coverage
These are also first generation cephalosporins used for outpatient therapy of community aquired staph infections.
Dosage: 250-500 mg bid
Cephalexin is dosed at 500 mg BID
Name the first generation cephalosporins
Cephazolin (Ancef, Kefzol)
Cephalexin (Keflex)
Cephradine (Velosef)
Why is cefuroxime rarely used for lower extremity infections?
Because cefuroxime is mostly indicated for H. influenza which is rarely ever found in the LE.
Clinical use and dosage of cefotaxime
Third generation cephalosporin that is used with clindamycin for diabetic foot infections.
Dosage 1-2g q8-12h
Cephtriaxone (rocephin)
Third generation cephalosporin with the longest halflife of all cephalosporins (7-8h) is also hepatically cleared (compared to renal like all the others)
doesnt cover staph as well as first gen but acts as an antibiotic bridge.
dosage: q-2g qq12-24 IV or IM max dose is 2g/day and can cause diahrrea.
Cephtazadine dosage and clinical use
Effective pseudomonas agent
1g q8h IV for skin
2g q12h IV for bone and joint infections.
(Renally cleared like most other cephs)
Cefdinir (Omnicef) clinical use and dosage
Excellent coverage for staph and strep and community aquired organisms (Mixed infections). Not effective for pseudomonas or enterobacters.
300 mg BID PO for skin infections
600 mg QD for RTI.
Name the fourth generation cephalosporin for the test
Cephapime
Covers pseudomonas, gram positive and gram negative agents.
Excellent for mixed skin infections.
1-2g q12h IV.
How do fluroquinolones work?
Inhibit bacterial DNA type II topoisomerase (gyrase)
What are the three main fluoroquinolone agents used in the US?
Ciprofloxacin
Levofloxacin
Moxifloxacin
What generation is ciprofloxacin and what are the dosages?
Second generation for UTI/RTI tx
Available in 100,250, 500 and 750 mg doses.
What generation is levofloxacin (levaquin) and what are the uses/dosages
Third generation
RTI/UTI
250,500,750mg doses or 500 mg IV daily.
