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. :-)


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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.

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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

Polyarthralgia

Source: Adapted from a case from the British Medical Journal at http://www.bmj.com/content/326/7394/859.pdf%2Bhtml

Case: A 45 year old woman presents with 3 months of progressively worsening arthralgia in the hands, knees and hips.

Ddx: degenerative joint disease, inflammatory arthropathy, secondary arthralgia

History

HPC
Inflammatory arthropathy: swelling, morning stiffness,
Red flags: nocturnal pain, pain at rest
Septic arthritis: recent viral and throat infection
Degenerative/osteoarthritis: repetitive use of hands, history of trauma to affected joints
Associated symptoms: Bowel or bladder symptoms (associated with sero negative arthropathies, IBD), eyes or skin symptoms, mood changes, altered sleep, malaise
Distribution: OA (large, weight bearing joints, carpometacarpal joint of thumb, DIP)

Euthyroid goitre

Approach to a euthyroid goiter.

Sources used:

1. The Journal of Family Practice at http://www.jfponline.com/Pages.asp?AID=5072
2. eTG (requires subscription)

Graves Disease vs Hyperthyroidism

Grave's disease is one of the possible causes of hyperthyroidism. This post is going to be about the signs and symptoms specific to Grave's, as opposed to those that you would observe in hyperthyroidism due to any causes.

Source: http://www.harrisonspractice.com/practice/ub/view/Harrisons%20Practice/141320/1.0/hyperthyroidism__graves%27_disease_

Hormone replacement therapy: risks & benefits

This topic is a controversial one because of a study by the Women's Health Initiative (WHI) which suggested that using hormone replacement therapy (HRT) increased a woman's risk of developing breast cancer and cardiovascular disease. While there are important risks and benefits that need to be discussed before one begins on HRTs, it is important to be critical when considering the implications of the WHI study.

Oliguria in a post-op patient

Source: Dr Michael Tam at http://vitualis.wordpress.com/2006/05/14/iv-fluid-therapy-in-post-operative-oliguria/

Common problem seen on overtime.

Step 1: Ensure that it is true oliguria.
- Check: IDC isn’t blocked, no post-operative urinary obstruction/retention (physical examination of the abdomen and a ward bladder scan optimally). [post-renal causes]

Step 2: Does the patient have pre-existing renal failure? This could explain the oliguria (look up the pre-op UECs).
- <30 mL/h = acute renal failure
- Ideal: >1 mL/kg/hr.

Step 3: Is the patient dehydrated? [pre-renal causes]
- Rehydrate with NS: 500ml bolus, then 500ml/hr
- Reassess & repeat if necessary

Step 4: If it doesn't help, this person may have intrinsic renal disease.

Also, an excellent post on maintenance fluids here: http://vitualis.wordpress.com/2006/05/01/maintenance-iv-fluids-in-euvolaemic-adults/

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Insertion of an NG tube

Contraindications
Maxillofacial trauma
- to avoid passage of tube into cranial vault through disrupted cribriform plate.

Esophageal abnormalities 
- Esp in patients with recent hx of ingestion of caustic substances or in those with esophageal strictures or diverticula

Altered mental status and impaired defenses
- NG intubation may precipitate vomiting so should be avoided in these patients.
- Endotracheal intubation is prefered.

Thomsen TW., Shaffer RW., Setnik GS. (2006). Nasogastric Intubation. NEJM. 354:17

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EXERPT from 'Guidelines for the management of acute coronary syndromes 2006'

Source: The Medical Journal of Australia at https://www.mja.com.au/journal/2006/184/8/guidelines-management-acute-coronary-syndromes-2006

Note: This is only an exerpt. Highlights are my own.

Summary of key recommendations
Acute management of chest pain

• The most important initial need is access to a defibrillator to avoid early cardiac death resulting from reversible arrhythmias.
• Aspirin should be given early (ie, by emergency or ambulance personnel) unless already taken or contraindicated.
• Oxygen should be given, as well as glyceryl trinitrate and intravenous morphine as required.
• Where appropriate, a 12-lead electrocardiogram (ECG) should be taken en route and transmitted to a medical facility.
• Where formal protocols are in place, prehospital treatment (including fibrinolysis in appropriate cases) should be facilitated.

Article: Glycoprotein IIb/IIIa

Article by Australian Prescriber here: http://www.australianprescriber.com/magazine/19/4/98/101/

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Use of Clopidogrel

Source: http://www.heartcarewa.com.au/facts7.php

WHO SHOULD HAVE IT AND FOR HOW LONG?

Clopidogrel alone:
Patients for whom Aspirin is indicated but where there is:

• Allergy to aspirin or NSAID
• Unacceptable risk of GI bleeding with Aspirin

Clopidogrel combined with Aspirin:

1. (i) Acute coronary syndrome (unstable angina or non-STEMI) patients (irrespective of whether angiography +/- subsequent stenting is performed and STEMI) – for at least 12 months.
   
   (ii) Post coronary stenting - for at least 12 months if a drug eluting stent is used.
   - for 3-4 months if a bare metal stent is used.
   
   If Clopidogrel therapy needs to be discontinued for any reason within these time frames it is very important for management to be discussed with the patient’s cardiologist in view of the risk of acute stent thrombosis.
   
   
2. Patients who have an ischaemic event (cardiac or neurological) while on Aspirin – indefinite.
   
   
3. High vascular risk patients
   
   - diabetic with vascular disease
   - previous CABG surgery
   - known severe vascular disease
   - recurrent ischaemic episodes (cerebral or cardiac) benefit demonstrated for up to one year.
   
   (Combination therapy has not been shown to be of benefit for primary prevention, even in high risk individuals)
   

NOTE:

• One recent study has indicated that taking proton pump inhibitors concurrently with Clopidogrel, may decrease antiplatelet activity. Somac does not have this effect and until the situation is clarified, it may be prudent for patients to switch to Somac if they are taking Clopidogrel. Patients should not stop Clopidogrel without seeking definitive medical advice.
• The addition of Clopidogrel to Aspirin increases the risk of serious bleeding by 2.7 to 3.7%.
• Nearly all patients with the above indications qualify for approval of Clopidogrel under the Australian PBS schedule.
  
• Contraindications to Clopidogrel
  - hypersensitivity
  - active pathological bleeding such as peptic ulcer or intra-cranial haemorrhage.

Dr Bernard Hockings
R.F.D.  M.D. (WA)  M.B.B.S. (WA)  F.R.A.C.P.  F.C.S.A.N.Z.
Clinical Associate Professor in Medicine UWA
Reference :2002 European Society of Cardiology Guidelines
Reviewed February 2009

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