CDR Contents

CDR/Clinical Decision Rules Guides

Computations, Others

Canadian C-spine Rule

Canadian CT Head Rule

CHADS2

LRINEC

NEXUS

PERC

Others:

Severe Pneumonia vs Severe Sepsis

Lumbar Pain -- when to LXR

Links:

ACEP Clinical Policies

ACLS 2010 Pocketguide

Dr Smith's ECG Blog

emcrit.org

ECG of the Week (Medscape)

ECG of the Month (theheart.org)

mdcalc.com

Paucis Verbis

Computations/Numbers: convert US to SI units

• Anion Gap = Na - (Cl + HCO3) = 8-16. If you have lactate value, you can subtract it from AG. eg. if AG = 16 and lactate is 6, then AG is 10 which is normal and no need to further look for mudpiles
• Corr. AG = AG + 0.25 x (40-Alb). Low albumin leads to underestimation of AG if not corr.
• Corrected Sodium: Corrected sodium ( mmol/L ) = measured Na + 2 x (plasma glucose - 5.6 ) 5.6 due to translational hyponatremia; high glucose leads to shift of water from ICF to ECF diluting and decreasing the sodium 1.6 mEq/L for every 100mg/dL (5.6 mmol/L) of glucose. Na corrects itself once glucose level is corrected. This formula actually underestimates sodium level.
• Urea/Crea = prerenal if >0.1 (intrinsic if less)
• Serum Osmolality = 2*Na + urea + glucose + ethanol (optional); 280-295
• Osmolal Gap = meas. osm - calc. osm; ≤10 normal. Unmeasured osmotically active substance include methanol, mannitol, ethyl glycol, sorbitol (MMES)
• HHS: glucose >33.3, pH >7.3, HCO3 >15, osmolality >320 mOsm/kg
• DKA: glucose >11, pH <7.3, HCO3 <15, ketonuria or ketonemia
• Mild DKA, pH/HCO3 <7.3/18; moderate DKA <7.25/15; severe DKA <7/10 link

Bleeding GIT

Stable: suspected of Melena/hematochezia/hematemesis

Hx:

• Hx of Bleeding GIT (Endoscopy/Colonoscopy)
• EtOH
• Meds: Aspirin/Plavix/Warfarin/other anticoagulants/NSAID/TCM/Steroid
• Cocaine/Sympathomimetics: ulcer
• Pain/No pain doesn't correlate with endoscope
• Hx of liver disease/heart failure

PE

• Abdominal exam
• Cirrhosis
• Rectal: look for fissures/hemorrhoids/anoscope

Labs

• ECG if anemic
• FBC/PT/Urea/Type and screen
• NG aspirate and lavage in ED: low sensitivity for hematochezia/melena (without hematemesis); Academic Emergency Medicine Feb 2010
• No imaging

*80% will need rebleed, only 20% needs to catch, but this patients are those with liver disease, on steroids, etc

Screening/Scoring = Non variceal bleeding: All common sense

- Blatchford score, Modified Glasgow Blatchford score, Rockall, Lee

* assume it's upper always: more common, more commonly fatal, you can do something

* assume it's variceal (not ulcer)

* if unstable, NG tube always! varices are not contraindicated

Corrected sodium underestimates sodium

Hyperglycemia lowers serum sodium levels; the degree to which has been updated from the previous dogma of:

Conventional Units: For each 100 mg/dL (over 100 mg/dL) the blood glucose rises; the measured serum sodium should have 1.6 mEq/L added to it in order to correct for the effect of the hyperglycemia.

SI Units: For each 5.6 mmol/L (over 5.6 mmol/L) the blood glucose rises; the measured serum sodium should have 1.6 mmol/L added to it in order to correct for the effect of the hyperglycemia.

In an interesting trial where the effects of hyperglycemia on sodium levels were actually measured, Hillier, et al. demonstrate that the correction factor of 1.6 is inaccurate and leads to serious underestimation of serum sodium levels; especially in those patients with blood glucose concentrations of >500 mg/dL. The clinical information from this; study, is that a factor of 2.4 is more appropriate.

We are now utilizing the 2.4 adjustment factor. The formulas for each are below:

Conventional Units:
Glucose = mg/dL Sodium = mEq/L For each 100 mg/dL (greater than 100 mg/dL) the blood glucose rises; the measured serum sodium should have 2.4 mEq/L added to it in order to correct for the effect of the hyperglycemia.

• Corrected Serum Sodium = Measured Serum Sodium + [(Glucose measured - 100)/100]x2.4

SI Units: For each 5.6 mmol/L (greater than 5.6 mmol/L) the blood glucose rises; the measured serum sodium should have 2.4 mmol/L added to it in order to correct for the effect of the hyperglycemia.

• Corrected Serum Sodium = Measured Serum Sodium + [(Glucose measured - 5.6)/5.6]x2.4

Reference:
Hillier TA, et al. Hyponatremia; evaluating the correction factor for hyperglycemia. Am J Med April 1999;106:399-403. Huffman, GB. Adjusting Sodium Levels in Patients with Hyperglycemia. Am Fam Phy. 15 October 1999;60(6):1798.