Saturday, November 21, 2015

Study group discussion: Mannitol in cerebral edema and pulmonary edema

Why isn't mannitol used in pulmonary edema? And why is it used in cerebral edema?

Mannitol would expand the intravascular volume, increasing cardiac output and causing pulmonary edema (more fluid going to the lungs than it can drain.)

(Assuming the pulmonary edema is due to CHF:) The increased hydrostatic pressure proximal to the left atrium causes transudation in the lungs. Although mannitol can act as a diuretic, it initially increases plasma volume due to its effects on elevating plasma oncotic pressure.

Increased plasma volume --> increased left atrial preload in the face of decompensation that already occurred even at a lower preload --> increased LAP (PCWP) with further decompensation --> exacerbation of pulmonary venular transudation.

So basically, it causes edema by volume overload.

It's blood brain barrier (BBB) that allow us to use mannitol for brain edema. Since no such barrier is there in lungs, mannitol can cross capillaries into alveoli and worsen it. Even in cerebral edema, we give mannitol only when the BBB is intact. Otherwise, mannitol can create havoc there too.

Infusion of hypertonic solutions of any effective small molecular weight solute (eg hypertonic saline, mannitol or urea) will dehydrate the brain. In the peripheral capillaries, these solutes are not effective at exerting an osmotic force because they can easily cross these capillary membranes.

Neuropathic joint disease

Hey everyone!

Today, I felt like sharing random things that I learnt today. It's about neuropathic joint disease - Destructive joint disease due to loss of pain and proprioception.

Neuropathic joint resembles osteoarthritis (Osteophytes, loose bodies, loss of articular cartilage, etc.)

I couldn't think of neuropathic joint disease as  a differential today because I was so caught up in osteoarthritis!

The distribution of joint involvement depends on the underlying neurologic disorder.
Tabes dorsalis: Hip, knee, ankle.
Syringomyelia: Glenohumeral joint, elbow, wrist.
Diabetes: Tarsal and tarsometatarsal joint.

This is a major clue. The joint distribution.

Diabetes mellitus is the most common cause of Charcot's joint.

Other causes of Charcot's joint include yaws, leprosy, Charcot Mary Tooth disease and meningomyelocele.

That's all!

I cannot feel, what is real..

- IkaN

Friday, November 13, 2015

How to remember HOCM is an Autosomal Dominant disease

Hey!

HOCM is hypertrophic obstructive cardiomyopathy.

HOCM is the most common cause of sudden cardiac death in ADolescents.

HOCM is Autosomal Dominant.

Fun fact: Most common cause of sudden cardiac death in children in Aortic Stenosis.

-IkaN

Thursday, November 12, 2015

Next best step in management in ST depression and ST elevation in acute coronary syndromes

This is a discussion I had with a lot of people. My questions are put in inverted commas.

"I don't understand the next best step in the management in acute coronary syndromes. If there's ST elevation MI, you do angioplasty. But when there was a ST depression, they preferred heparin after aspirin even when angioplasty was in the options. Why is that? Why does the management change depending on elevation or depression?"

ST elevation means transmural ischemia so maybe angioplasty is the only way to restore flow. ST depression means subendocardial ischemia so occlusion isn't complete. Heparin and blood thinners might work.

"But then if you can do angioplasty (Catherization lab available), why give heparin?"

They do send for angioplasty later. Heparin can be given immediately to prevent the situation from getting worse.

"But then again, why wouldn't you do that with ST elevation too?"

ST elevation means the occlusion is complete. Heparin wouldnt be effective. In NSTEMI and unstable angina, there's still some lumen viable.

"Patients with MI with ST-segment depression should not be treated with fibrinolysis. Why isn't fibrinolysis done in ST depression angina?

We say that the occlusion isn't complete because there is subendocardial ischemia in ST depression and we give heparin to prevent further occlusion. But why not give streptokinase? Why not eradicate what is already formed instead of trying to prevent progression of clot?"

Because fibrinolysis treatment has it's own side effects and it's not effective in all the cases. It's contraindicated because studies have shown it does more harm than good in only ST depression.

Like, for example, there is reperfusion injury which would might make the only subendocardial infarct into a transmural one. 3 in ten patients end up with cerebral haemorrhage. There are so many other clauses.

Hence it's only indication is a transmural infarction.. The damage is already great. Irrespective of using t-PA the patient condition is critical.

That's all!

Thank you everyone who helped me out on this one.

-IkaN

Saturday, November 7, 2015

Study group discussion: Pathogenesis of diarrhea in medullary carcinoma of thyroid

By which mechanism, does medullary thyroid cancer cause secretory diarrhea?

Medullary thyroid carcinoma is usually associated with men syndrome in which we get VIPoma, which is associated with diarrhoea.

Upto date: "Systemic symptoms may occur due to hormonal secretion by the tumor. Tumor secretion of calcitonin, calcitonin-gene related peptide, or other substances can cause diarrhea or facial flushing in patients with advanced disease. In addition, occasional tumors secrete corticotropin (ACTH), causing ectopic Cushing's syndrome."

Colonic function was markedly impaired in three ways: (a) water absorption was decreased by half; (b) as the main excreted solutes were organic acids, a large electrolyte gap was recorded in faecal water, and (c) colonic transit time of the meal marker was very short, and was in agreement with the rapid transit of ingested radioopaque markers. These data strongly suggest that decreased absorption in the colon secondary to a motor disturbance is the main mechanism of diarrhoea in this case of medullary thyroid carcinoma, while calcitonin induced small intestinal fluid secretion suggested earlier is either non-existent, or only of minor importance.
Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1433550/

My dd for tumors and secretory diarrhea (someone wants to add):
- carcinoid tumor
- VIPoma
- Gastinoma
- Medullary thyroid cancer

Macrocytic anemia mnemonic

Mnemonic for Macrocytosis (Non B12 causes):

ALPHA NERD

Alcohol
Liver disease
Pregnancy
Hemolysis (especially chronic)
Agglutination

Neoplasia (Including myelodysplasia)
Endocrine (Hypothyroidism)
Reticulocytosis
Drugs (Especially myelosuppressives like chemotherapy, anti-HIV meds)

This awesome mnemonic was written by Adnan Arif.

-IkaN

Tuesday, November 3, 2015

Jay

Hello guys, I'm Jay, the newest author here ( edit : back in 2015...lol, by 2019, I'm the 4th oldest author here.) in the Medicowesome, and I'm really really...like REALLY....excited to be here! :D

The flow of CSF Mnemonic

Hello guys, It's Jay once again. Today I'm going to tell you a mnemonic on how to memorize the CSF flow. Interesting eh? 

OK Let's get to work!

First of all let us know the CSF flow as it flows!

Lateral Ventricle → foramen Monroe→Third ventricle → Sylvius Aqueduct→ fourth ventricle→ foramen Magendie → foramen Lushka→Subarachnoid space→Arachnoid Villi→Superior Sagittal Sinus


The mnemonic is

Lady Monroe's Three Siblings Fought, for Magical Lights Seeing Arrogant Seniors

Hope it would help you guys! Thanks! See you later !


Sunday, November 1, 2015

Auscultating breath sounds mnemonic

While Auscultating the Chest of patient and analysing Type of breathing, whether it's Bronchial or Vesicular.

Remember GRIP

1. Bronchial breathing:
Gap is present between Inspiration & expiration.
Respiration shows Inspiration & expiration equal length
Intensity is loud.
Pitch is high.

2. Vesicular Breathing:
Gap is absent.
Respiration shows Expiration is short.
Intensity is low.
Pitch is low.

This post was written by Adnan Arif. Thanks Adnan! (:

-IkaN
Related post: Abnormal breath sounds mnemonic

Submissions: Ankylosing Spondylitis (Radiological signs notes)

These cool notes were written by Shireesha Mallik. Check em out!
Ankylosing Spondylitis (Radiological signs notes)

Antithyroid drugs mnemonic

1. Durgs that inhibit hormone synthesis (Antithyroid drugs):
Propylthiouracil, methimazole, carbimazole.

Mnemonic: Professor Met Carby

2. Drugs that inhibit thyroid trapping (Ionic inhibitors):
Nitrates (NO3), thiocyanates (SCN), perchlorate (ClO4) .

Mnemonic:  NTP

3. Inhibit hormone release:
Iodine, iodides of Na & K, organic iodides.

Mnemonic: I prevents release (Iodine, it's salts and organic form.)

4. Destroy thyroid tissue: Radioactive Iodine (I 131, I 123, I 125)

Mnemonic: Iodine normal is 128 (+3 &-3 are radioactive so is I 123)

That's all!

The mnemonics were submitted by Sareer. Thank you, Sareer, you're awesome.

-IkaN