Tuesday, January 31, 2012

Romberg Test

This morning we talked about the Romberg test.

The ability to maintain a steady posture depends on input from 2 of the 3:
o vestibular apparatus
o eyes
o propioception from feet
The cerebellum coordinates the input from all three.

ROMBERG test tells you about problems in propioception or the vestibular apparatus.
The test start with the patient standing with heels together and eyes OPEN. If there is unsteadiness, then there is cerebellar ataxia. If the patient is steady, then ask the patient to stand with eyes CLOSED. Inability to stand for 60 seconds with eyes CLOSED is a positive Romberg sign, and reflects vestibular disease or sensory ataxia.

*The test was named after the German neurologist Moritz Romberg (1795-1873).

Ref: Evidence-Based Physical Diagnosis, McGee. 2007.

Thursday, January 26, 2012

"what about my water pill, doctor?"

This morning we briefly talked about the mechanism of action of furosemide (lasix). This drug is a loop diuretics that inhibits the Na-K-2Cl channel in the thick ascending limb of the loop of Henle on the luminal side.

The efficacy of Furosemide is dose-dependent, but a plateau is reached in which even higher doses produce no further diuresis (when all the channels are saturated). The bioavailability of furosemide is only about 50%, so IV is twice as potent as oral. The drug is renally cleared.

IV therapy is preferred in patients with decompensated heart failure initially because drug absorption may be slowed by decreased intestinal perfusion and mucosal edema.

Furosemide is a sulfonamide drug so can cause hypersensitivity reactions, but patients with a history of allergy to sulfonamide antibiotics usually tolerate furosemide with little cross-reactivity.

Another side effect furosemide to be aware of is ototoxicity.

Here is a review article on diuretic therapy.

Wednesday, January 25, 2012

Pleural Effusion and Ultrasound

At Gel Rounds today, we discussed pleural effusion. The image above is the ultrasound image of a small right sided effusion. The top of the image represents the probe resting on the chest wall, the dark area (e) is the effusion. The Bright band between (e) and the liver is the diaphragm (d). The lung is seen superior and deep to the effusion.

Now that you know how to identify pleural effusion with the ultrasound, use it in addition to your physical exam when doing a bedside thoracentesis.

Thursday, January 12, 2012

Prothrombin-Complex Concentrates (PCC )

This morning we discussed the use of PCCs in reversing the INR. PCC is the combinations of vitamin K-dependent coagulation factors (ie, factors II, VII, IX, and X). It is used to normalize the INR and acts more rapidly than FFP or vitamin K alone.

PCC available in Canada is Octaplex (there are more in the market). This is a human blood product derivative (not a recombinant).

Advantage of using PCC is the much lower volume load compared to FFP. Thrombotic complications (such as DIC or MI) have been reported with PCC, but this risk is difficult to quantify.

Vitamin K should be given if you need to completely reveres INR even when using PCC to avoid delayed secondary rise in the INR as the coagulation factors are metabolized (remember factor VII has a half-life of four to six hours in vivo).

The cost of INR reversal with PCC is between $1000-$3000 USD.

Here is a review on reversal of vitamin K agonist therapy.

Monday, January 9, 2012

The Perfect Storm

This morning we discussed a case of thyroid storm. This is a life-threatening condition, characterized by exaggerated symptoms of hyperthyroidism.

Thyroid storm can present as first time presentation of thyroid disease, but more commonly seen in those with long standing history of hyperthyroidism triggered by infection, trauma, surgery, post-partum, or an iodine load.

Patients are often tachycardic with hemodynamic instability, and can have hyperpyrexia, altered LOC, and GI symptoms. Given the high mortality associated with thyroid storm (20-30%), a high index of suspicion should be kept in patients with history of thyroid disease.

Here is a review on thyroid emergencies.