Eponymous Triads

Good things come in threes? Here's a list of triads we use in clinical diagnosis.

Cushing's triad --> raised ICP

• Hypertension
• Bradycardia
• Irregular respiration

Beck's triad --> cardiac tamponade

• Distant heart sounds
• Hypotension
• Distended jugular veins

Virchow's triad --> hypercoagulable state

• Endothelial damage
• Venous stasis
• Hypercoagulability

Whipple's triad --> hypoglycemic state

• Symptoms of hypoglycemia 
• Low blood sugar
• Relief of symptoms with sugar intake

Charcot's triad --> ascending cholangitis

• RUQ pain
• Jaundice
• fever

Use of magnesium in arrhythmias

I've always wondered why we use magnesium to deal with many arrhythmias (at least as an adjunct) and have to say that all the doctors I've asked here don't actually know. Anyway today I was reading one of the USMLE books and it says that MgSO4 decreases calcium influx, thus reducing the early afterdepolarizations that perpetuate many arrhythmias. The paragraph was in relation to dig toxicity but I'm guessing the reason applies across the board. Was so excited to finally find the reason for magnesium. :-)


**See the disclaimer**

Pupillary responses

Looking at the pupils can sometimes be helpful, particularly in an unconscious patient. There are many causes of dilated pupils but if you're lucky and a patient comes in with constricted pupils then this narrows down the possible causes significantly.

A constricted pupil is one that is less than 2mm under normal lighting conditions. Note that the pupils will constrict if you shine a torch into them!

Bilateral pinpoint pupils
- Opiates (Heroin, Fentanyl, Codeine, Methadone, Morphine) stimulate the parasympathetic side of the autonomic nervous system causing pupil constriction. Look for track marks and a past history of drug use.
- Pontine hemorrhage (brain stem)
- Organophosphate chemicals (pesticides, Sarin gas). Look for SLUDGE presentation (salivation, lacrimation, urination, defecation, emesis)
- Other drugs (neuroleptics, EtOH, benzos, isopropryl alcohol, lithium)


Bilateral dilated pupils
- Anticholinergic drugs (TCA)
- Adrenergic drugs (cocaine, amphetamines) - but these don't usually lead to coma unless complicated by seizures or cerebrovascular events.  
- Other drugs (quinine, baclofen, barbiturates, other sedatives like carbamazepine)
- Raised ICP
- Brain death

References I used:
1) http://theemtspot.com/2009/04/23/rapid-diagnosis-pinpoint-pupils/
2) http://curriculum.toxicology.wikispaces.net/Pupil+Size+and+Reaction

There is also an online teaching syllabus for toxicology at WikiTox.

**See the disclaimer**

Infectious nucleosis/Glandular fever

Today I was involved in a case on infectious mononucleosis, also known as the Kissing Disease. I found this case very interesting so am going to write about it here. Sources used for this post include direct experience and eMedicine.

Infectious mononucleosis is a syndrome comprising fever, pharyngitis and lymphadenopathy. It is caused by infection by Epstein-Barr Virus (EBV). It is transmitted via intimate contact with body secretions, primarily oropharyngeal secretion (ie. kissing). In a host, EBV will affect the reticular endothelial system (liver, spleen, peripheral lymph nodes). Pharyngitis is due to proliferation of EBV-infected B lymphocytes in the lymphatic tissue of the orophrynx.

Cutaneous drug reactions

A patient popped in a few weeks ago with a diffuse maculopapular rash following recent administration of a new medication. The rash had started on the trunk and was spreading to the limbs. That, and the fact that we need to prep this scenario for our finals has resulted in this blog post.

Source: Best Practice (a subscription is necessary), Harrison's Practice

Spectrum of drug induced cutaneous reactions. Other conditions to consider include fixed drug eruptions and DRESS* (drug reaction with eosinophils and systemic symptoms).

Precordial Thump

I've long wondered about the place of the precordial thump in the management of acute cardiac arrhythmias. Had some time today so did a bit of reading. This is a summary of what I found.

Source: Wikipedia (search term "precordial thump"), Merckmanuals,

1. The procedure is outside the scope of first-aid treatment and requires, at minimum, training in advanced cardiac life support (ACLS). Incorrect application of this technique can result in fracture of the sternum/rubs or 'commotio cordis' aka cardiac arrest due to blunt trauma. This procedure if done incorrectly can lead to asystole or a more fatal arrhythmia.
   
   

Polypills (Cardiology)

I will comment on this after my exams. Came across a polypill trial from Britain here:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0041297

This polypill contains the following active ingredients:
amlodipine 2.5 mg, losartan 25 mg, hydrochlorothiazide 12.5 mg and simvastatin 40 mg

It is different from the one V.Fuster has been working on in New York/Madrid.

Fuster talks about his version of the polypill here: http://www.empowereddoctor.com/what-is-the-polypill