Tuesday, August 28, 2007


Screening for microalbumuria in non-diabetics is a good way to screen for CV risks. The microalbumuria is caused by endothelial dysfunction.

SAAB drugs for use in acute coronary syndrome

  • Statin
  • Ace inhibitor
  • Aspirin
  • Beta blocker

Electrolyte imbalances that occur in diabetes

  • Hypocalcaemia - kidney doesn't activate vitamin D -> decreased GIT absorption of Ca
  • Hyponatraemia
  • Hyperphosphataemia - it can't be excreted. Treatment is by giving a phosphate binder e.g. mylanta.

Treatment of endocarditis

Endocarditis requires 6 weeks of IV antibiotic treatment. This length of time is required because it is difficult for antibiotics to penetrate to the valve cusps which are relatively avascular.

Thursday, August 23, 2007

Calcium channel blockers

Mechanism of action

Calcium channel blockers have a negative inotropic effect - they decrease the force of contraction of the myocardium.

They block L-type voltage gated calcium channels in the heart and blood vessels. This prevents calcium levels from increasing as much in the cells when stimulated, leading to less contraction.

They also decrease total peripheral resistance by dilating the blood vessels, and decreasing cardiac output by lowering the force of contraction. Because resistance and output drop, so does blood pressure. With low blood pressure, the heart does not have to work as hard; this can ease problems with cardiomyopathy and coronary disease.

Unlike with beta-blockers, the heart is still responsive to sympathetic nervous system stimulation, so blood pressure can be maintained more effectively.

Many calcium channel blockers also slow down the conduction of electrical activity within the heart by blocking the calcium channel during the plateau phase of the action potential of the heart. This causes a lowering of the heart rate and may cause heart blocks (negative chronotropic effect) of calcium channel blockers.


There are 2 classes of CCBs:
  1. Dihydropyridines

    • Used to reduce systemic vascular resistance and arterial pressure, but are not used to treat angina because the vasodilation and hypotension can lead to reflex tachycardia.
    • This CCB class is easily identified by the suffix "-pine" e.g. Amlodepine, Felodipine.

  2. Non-dihydropyridines

    • Relatively selective for myocardium, reduce myocardial oxygen demand and reverse coronary vasospasm, and are often used to treat angina.
    • They have minimal vasodilatory effects compared with dihydropyridines.
    • Action is intracellular.
    • E.g. verapamil.


  • Atrial fibrillation or flutter - to control heart rate via negative chronotropic effect.


  • Avoided (or used with caution) in individuals with cardiomyopathy due to negative inotropic effect.
  • Non-dihydropyridine CCBs should not be combined with beta-blockers because they are both negative inotropes and affect the AV node.
  • Wikpedia, http://en.wikipedia.org/wiki/Calcium_channel_blocker

Sunday, August 19, 2007

Boils, furuncles and impetigo

Boils (furuncles) are localised, subcutaneous pyogenic infections, most frequently by Staphylococcus aureus, originating deep in a hair follicle.

Impetigo is a contagious superficial pyoderma, caused by Staphylococcus aureus and/or group A streptococci, that begins with a superficial flaccid vesicle that ruptures and forms a thick yellowish crust.

  • Stedman's Electronic Medical Dictionary, v5.0
  • Image from http://www.clinical-virology.org/gallery/images/non_viral/impetigo-1.jpg

Saturday, August 18, 2007

Wound swabs

Contamination = the presence of organisms in a wound that are not multiplying.

= the presence of organisms in a wound that are multiplying but causing negligible host reaction. Colonisation can have a detrimental effect on wound healing, but as the ‘classic’ signs of infection do not accompany it, is often not identified.

= the presence of organisms in a wound that are multiplying and causing a host reaction.

Signs of infection

  • delayed healing
  • purulent discharge from the wound
  • Green, yellow or brown wound exudate or increased amount of wound exudate
  • Offensive odour
  • Inflammation and erythema of the wound and surrounding tissue – may include cellulitis
  • Hypergranulation tissue
  • Systemic signs: fever, malaise/lethargy
  • Increased or unusual pain (Note: persons with diabetes may not experience this)
  • Confusion
  • Elevated BSL in diabetics
  • Leucocytosis

Indications for Wound Swabbing

  • An obvious wound exists and the surface can be sampled
  • Clinical signs of infection
  • Viable tissue exists - not slough or necrotic tissue (although these need to be removed via debridement)
  • Templeton S., Royal District Nursing Service of SA, http://www.rdns.org.au/research_unit/Newsletters/11_Wound_Sep02.pdf