1. Potassium replenishment
- K-lor capsules are very large, for many people they sit at the LES and cause erosive esophagitis. Doxycycline does the same thing. If someone needs K, you're better off giving liquid K (although it tastes bad).
- 0.1 mEq K below = 20-40 mEq deficit. For a 1 mEq deficit, replenish with 40-60 mEq PO q4-6 or 10 mEq IV q1 hour if its urgent.
2. Syphillis
- in the CSF, the VDRL is specific but not sensitive (70% false negative), while FTA-ABS is sensitive. It's the opposite of the serum pattern. A negative csf VDRL does not rule out neurosyphillis!
- In the US, >50,000 cases diagnosed every year
- primary syphilis - 10-90 day incubation period, chancres
- secondary syphilis - weeks to months later, diffuse symmetric rash (although can take any form except vesicular) plus general malaise symptoms- fever, anorexia, etc. many people will have spirochetes in their csf at this point.
- latent syphilis
- late syphillis occurs 1-30 years after initial presentation will occur in 25-40% of people with untreated syphilis - cardiac (aortitis), Neuro (transient meningitis, cranial neuropathies ESP optic, facial, menigovascular - arteritis of vessels in subarachnoid space leading to thromboses)
- otosyphilis, oculosyphilis can occur too
- tabes dorsalis can present with lancing pain,
3. Fourniers gangrene
- 100% mortality with antibiotics alone, 40-80% mortality even with surgery
- "Localized infection adjacent to a portal of entry is the inciting event in the development of Fournier gangrene. Ultimately, an obliterative endarteritis develops, and the ensuing cutaneous and subcutaneous vascular necrosis leads to localized ischemia and further bacterial proliferation. Rates of fascial destruction as high as 2-3 cm/h have been described.... testicles usually spared because they have a separate blood supply (testicular arteries, from aorta)" (medscape)
4. Anti-Xa levels
- Lovenox levels are monitored with anti-Xa (all heparin-based a/c can be monitored with this); lovenox only needs monitoring in people who need dose adjustments, like people with ESRD
- Adjustment for renal function: increase the interval, rather than decrease the dose.
- Anti-Xa test: put antithrombin and factor Xa in a tube, add patients' serum; if there is a lot of lovenox in the serum, it will cleave all the factor Xa and there will be little remaining (this measured with chromophores that are cleaved upon enzymatic cleavage). This is then plotted on a concentration-activity curve to determine the amount of "anti-Xa" activity within the patient's serum
- Therapeutic anti-Xa levels: lovenox (0.5-1.2), unfractionated heparin (0.3-0.7)
- Prophylactic anti-Xa levels: lovenox (0.2-0.5), unfractionated heparin (0.1-0.4)
5. Low molecular weight heparins: 
- Lovenox comes in 80 mg pens
- Dalteparin does not accumulate even in people with renal failure
6. Antibiotics medley
- Keflex is good for wound infections, but it must be taken 3-4 times a day. Covers from MSSA to non-resistant GNR
- Augmentin has similar coverage, but is only BID. Better coverage of resistant GNR, coverage of anaerobes (no cephalosporins have any anaerobic coverage)
- Bactrim can cause a pseudo-type 4 RTA (decreased response to aldosterone, hyperkalemia) even at low doses. Especially relevant in ESRD patients.
- Many antibiotics affect warfarin metabolism in the liver - bactrim, cipro, macrolides (clarithro, erythro), flagyl! There are differences from what is seen in case reports (bad times) and what is seen when you co-administer warfarin and these antibiotics in healthy volunteers (not so bad!)
- "Some investigators advise that the hypothrombinemic response to warfarin can increase when acetaminophen is taken in a dosage of more than 2 g per day for longer than one week.3(pp7–8) Recent information suggests that the warfarin-acetaminophen interaction may be clinically significant at even lower dosages of the pain reliever. One case-control study identified acetaminophen as a cause of 30 percent of INR values greater than 6.0 in patients taking warfarin.4 This response occurred with as few as seven 325-mg tablets of acetaminophen. The proposed mechanism is a reduced capacity of cytochrome P450 enzymes caused by acetaminophen and resulting in decreased metabolism of warfarin." (from above article.... interesting)
7. Premature beats
- PAC: p-wave comes early, then the pacemaker resets. Comes from ectopic foci-- P wave morphology and PR interval are different. The PAC can be conducted normally or blocked through AV node.
- PVC: p-wave comes early, pacemaker resets. Wide QRS. Can be experienced as a "skipped heart beat", because the ventricles contract before they can adequately fill with blood.
- Atrial bigeminy: every normal sinus beat is followed by a PAC. Often due to mild irritation of atria: try stopping caffeine, checking electrolytes. Usually harmless
- Ventricular bigeminy: every normal sinus beat followed by PVC. The "true" heart rate will be half as fast as the measured heart rate-- because the PVC beats are not good beats, as the ventricles don't fill completely so the cardiac output is bad during those beats. Can occur in young healthy people and be fine-- they may be able to sit at an effective rate of 30 BPM. Can cause fatigue though, for decreased CO. If its severe enough you can treat this with ablation.
8. Escape rhythms/beats
- "escape" = higher levels of pacing have failed, now relying on downsteam pacemakers (junction, ventricular fascicles)
- Junctional escape rhythm: usually 40-60 bpm, narrow complex, may or may not have a p-wave (may conduct sightly retrograde and have an inverse form, may have no P wave.
- Ventricular escape rhythm: 20-40 bpm, wide complex, no p-wave for sure.
9. AV node blocks
- First degree: PR > 0.2 ms (one large box)
- Second degree type I wenckebach's: PRs lengthen than QRS drops; the ratio can be 1:2 - 1:10.
- Second degree type II: PRs same length, QRS randomly drops. vs PAC-- second degree blocks are sinus rhythms, so the P-P intervals are symmetric (ie not premature).
- Third degree: complete block. Frequently occurs after inferior wall MIs, as the RCA supplies the SA and AV node with blood. These people need a pacemaker, although the urgency varies; if they're healthy and compensating well, they might be able to stay on the floor and move to the OR at a leisurely pace to get the pacemaker (although should be within a day or so). If they're old and not able to compensate, they will need an ICU admission, an urgent temporary venous-catheter-placed-pacemaker and a trip to the OR as soon as feasible. Remember: in third degree block you are relying on ventricular escape rhythms, and those are really slow. An old person with lots of comorbidities may not be able to adequately perfuse at 20 bpm.
10. Bundle branch blocks:
- Most of the heart depolarizes R to L, but the septum depolarizes L to R
- RBBB: AV node to L fascicle is normal, and septum is able to depolarize normally. On the L lateral leads (V5, V6) you'll see a small Q (from the septal depolarization), a sharp R, and a widened S. On the right-side (V1, V2), you'll see a small R from the septal depolarization, a sharp S from the L ventricle depolarizing, and then a large R from the R side depolarizing (visible because the L ventricle is already done, so the direction of the vector will be very clearly towards the R) -- rabbit ears, rsR'. T wave inversions is normal.
- LBBB: AV node to R fascicle is normal, but septal depolarization and L side depolarization are both messed up. L lateral leads will see a widened R wave as the L ventricle depolarizing in a slow, inefficient way. R lateral leads will see a big widened S wave for the same reason-- L ventricle depolarizing.
- Hemi-blocks: Left bundle branch has anterior and posterior fascicle.
- L Anterior fascicular block is most common because it is supplied by the LAD. You get left axis deviation, Q1S3 (small Q in lead 1/avL, S wave in lead III), prolonged QRS
- L posterior fascicular block is less common because it has a dual blood supply- LAD and RCA. If you have ischemia of both, then you have bigger problems. Exact opposite EKG findings: R axis deviation, Q3S1, QRS prolonged.
- Combined blocks: L Anterior fascicular + RBBB because they are both supplied by LAD -- these have a high rate of progression to third degree AV block.