Saturday, June 30, 2012

Something basic - On Adenosine stress test

Adenosine causes vasodilation in the small and medium sized arterioles (less than 100 ┬Ám in diameter). When adenosine is administered it causes a coronary steal phenomenon, where the vessels in healthy tissue dilate as much as the ischemic tissue and more blood is shunted away from the ischemic tissue that needs it most. This is the principle behind adenosine stress testing.

Adenosine is quickly broken down by adenosine deaminase, which is present in red cells and the vessel wall.

Friday, June 29, 2012

On Belviq (lorcaserin)

Belviq is a new anti obesity pill approved by FDA and expected to have a huge demand.

The drug works by activating brain receptors for serotonin, a neurotransmitter that triggers sense of satiety and satisfaction. Makers of Belviq (Arena) claims that drug is designed to seek out only the serotonin receptors that affect appetite - But - central side effects are expected including headache, dizziness, fatigue, nausea, dry mouth and constipation. Diabetic patients may get encounter with hypoglycemia.

It would be interesting to watch from Intensive Care Medicine perspective any incident of Serotonin Syndrome. Also, cardiac valvular defect remains a concern as happened with fenfluramine in past. FDA has asked Arena to conduct studies once the drug reaches the market to determine whether it causes heart attacks or stroke in people who take it.

Thursday, June 28, 2012

Something to be aware about Pradaxa (Dabigatran) 

 According to FDA guidelines, Dabigatran potency get highly effected by enviromental humidity. Dabigatran is available both in bottles and in blister packs. Once a bottle of dabigatran is opened, the medication expires after four months. In commercially supplied Dabigatran the bottle-cap contains a humectant to reduce the humidity and prevent degradation of the medicine. Similarly, once the blister pack is open, drug degenrates in about 4 months.

Wednesday, June 27, 2012

A note on Phenytoin (Dilantin) stability

Phenytoin is very unstable when diluted even in normal saline. Precipitation may occur which is not visible. It is recommended to administer solutions immediately upon preparation.

Saturday, June 23, 2012

Q: What is the dose of Methylene blue in treatment of Methemoglobinemia? 


Answer: Methylene blue 1% solution (10 mg/ml) 1 to 2 mg/kg given intravenously slowly over five minutes followed by IV flush with normal saline. 

 In any case supplemental Oxygen should be administrated. 

 Methylene blue restores the iron in hemoglobin to its normal (reduced) oxygen-carrying state.

Friday, June 22, 2012

Q: What is the formula to convert S/F ratio to P/F ratio? 

 - PaO2/FiO2 and SpO2/FiO2 ratio 


Answer: S/F = 64 + 0.84*(P/F) 

 An S/F value of 235 corresponded with P/F ratio of 200 while S/F value of 315 corresponded with P/F ratio of 300. Study shows that validation database from 2031 measurements produced a linear relationship.

Sunday, June 17, 2012

Q: 34 year old male patient had LP (lumbar punture) 4 days ago but continue to complaint of severe headache. Analgesics are not working. What would be other simple recommendation?



Answer: Caffeine - 300-500 mg q4-6h


In severe cases Caffeine sodium benzoate (500 mg) in 1 liter of fluid (D5LR) can be given intravenously over one and a half hour. The patients usually have complete resolution of symptoms and no recurrence of headache.

Caffeine sodium benzoate is a simple treatment of post-lumbar-puncture headaches. It should be considered as a safe alternative to an epidural blood patch for the treatment of post-lumbar-puncture headaches.


A simple treatment of post-lumbar-puncture headache. - J Emerg Med. 1989 Jan-Feb;7(1):29-31.

Tuesday, June 12, 2012

Sympathetic Storming
Sympathetic storming after traumatic brain injury remains one of the most dramatic clinical scene particularly in neurological units. It occurs due to uncontrolled sympathetic surge with a diminish or unmatch parasympathetic response. Acording to Baguley criteria 5 out of the 7 clinical features should be present - tachycardia, tachypnea, hyperthermia, hypertension, dystonia, posturing, and diaphoresis. Various agents have been used for treatment (see review article below) but haloperidol may worsen the symptoms.

Dr. Blackman and coll. coined the term "PAID" - paroxysmal autonomic instability with dystonia- in Archives of Neurology March 2004.
References: click to get abstract/article

1.
Dysautonomia after traumatic brain injury: a forgotten syndrome? - J Neurol Neurosurg Psychiatry 1999;67:39-43 ( July )
2.
Paroxysmal autonomic instability with dystonia (PAID) - Arch Neurol. October 2004;61:1625.
3.
Paroxysmal Autonomic Instability with Dystonia After Brain Injury - Arch. Neurol. March 2004;61:321-328
4.
Riding Out the Storm: Sympathetic Storming After Traumatic Brain Injury - Denise M. Lemke, MSN CS-RN ANP CNRN - J Neurosci Nurs 36(1):4-9, 2004.

Monday, June 11, 2012

A note on Factor 7 (rVIIa) and thrombocytopenia

Factor 7 (rVIIa - Novoseven) is now significantly use as off label in uncontrolled bleeding. It may not be efective in the presence of severe thrombocytopenia and should be corrected prior to its administration.

Although there are case reports of the successful use of rVIIa in severe thrombocytopenia, a low platelet count is likely to predict a poor or partial response to rVIIa therapy. Its haemostatic effects are mediated by the thrombin it generates by both tissue factor (TF) dependent and independent mechanisms. The TF independent mechanism requires platelets for the direct activation of Factor X on their surface by rVIIa.

Sunday, June 10, 2012

Red urine during transfusion.
Q; You have been called to evaluate a patient who developed red-urine. At bedside, you noticed pRBC transufion in progress. What would be your first few immediate responses?


A; The first thing you need to determine is whether it is a transfusion reaction (hemolysis) or a pure hematuria. Send Urine or blood for centrifuge.

The onset of red urine during or shortly after a blood transfusion may represent hemoglobinuria from acute hemolytic reaction. To distinguish it from hematuria, if freshly collected urine is centrifuged, the urine sample remains clear red. If its pure hematuria, red blood cells settle at the bottom of the tube, leaving a clear yellow urine supernatant. Similarly patient's blood with centrifuge will turn free serum as a pink color from free hemoglobin in a clotted centrifuged specimen otherwise serum will be yellow if no transfusion reaction.

Other steps to take.

1. Halt the transfusion.

2. Send donor blood and patient's blood quickly to blood bank to make sure that right blood was transfused (repeat crossmatch and type) and for antibody screen, and direct and indirect Coombs tests.

If transfusion reaction is highly suspected:

3. Administer IV Benadryl, IV steroid, IV saline followed with IV lasix or with low dose dopamine to improve renal blood flow. Symptomatic treatment with acetaminophen.

4. Airway protection and if seems to be anaphylactic reaction, administer epinephrine (nebulizer treatment, SQ or IV drip depending on severity). Oxygen to keep saturation up.

5. Send complete lab workup including lytes, renal function (BUN/Cr), serum bilirubin level (peaks in 3-6 hours), Haptoglobin (binds to hemoglobin) , urine for hemoglobinuria, a repeat CBC (fails to show the rise in hematocrit because of intravascular or extravascular hemolysis) and DIC panel.

6. Hematology consult.
Management is largely supportive.

Saturday, June 9, 2012

Q: 32 year old otherwise healthy male with 2 weeks history of sinusitis presented with siezure. ER physician called you while he sent patient to CT scan. What would be your primary concern and line of action? 


 Answer: Neurological symptoms after prolong bout of sinusitis is highly suggestive of Subdural empyema.

 Subdural empyema is a neurosurgical emergency and beside instituting antibiotics and anti-seizure meds, it would be appropriate to ask neurosurgical service to review CT scan while patient is in neuroradiology department. It has a tendency to spread rapidly through the subdural space.

Friday, June 8, 2012

Q: What could be the supporting finding on lab in (Transfusion-related acute lung injury (TRALI)? 

 Answer: Laboratory findings may include unexpected haemoconcentration and a sudden fall in serum albumin.

Thursday, June 7, 2012

Q: Why vasopressin is preferable over epinephrine in cardio-pulmonary arrest due to cocaine overdose?


Answer: Epinephrine like cocaine has alpha-adrenergic effects. Because of this similarity in the cardiovascular effects, the administration of epinephrine to a patient who arrests in a hyperadrenergic state has been like "pouring gasoline over fire." 

 Moreover, cocaine prevents the reuptake of exogenously administered epinephrine. Therefore, if epinephrine is used, AHA Guidelines recommends that high-dose epinephrine should be avoided and that the interval for its administration be increased (q 5-10min). 

 Vsopressin offer considerable advantages over epinephrine in cardiac arrest secondary to cocaine toxicity. The hyperadrenergic state caused by cocaine increases myocardial oxygen demand and vasopressin increases coronary blood flow, and thereby myocardial oxygen availablity. Also, cocaine toxicity causes acidosis and epinephrine loses much of its effectiveness in an acidotic enviroment, whereas vasopressin demonstrates good efficacy even with severe acidosis.

Wednesday, June 6, 2012

Q: Name an epileptic drug which can be given rectally if required?


 Answer: Depakote (valproic acid) Dilute syrup 1:1 with water for use as a retention enema; loading dose: 17-20 mg/kg one time; maintenance: 10-15 mg/kg/dose every 8 hours

Tuesday, June 5, 2012

Q: Which of the following medicines can cause "Red Man Syndrome"? 

 A) Ciprofloxacin, 
 B) Amphotericin B, 
 C) Rifampcin 
 D) Vancomycin 
 E) All of the above 

 Answer: All of the above Antibiotics such as ciprofloxacin, amphotericin B and rifampcin can also potentially cause red man syndrome beside vancomycin. Like vancomycin, they are capable of causing direct degranulation of mast cells and basophils. Red man syndrome is amplified if these antibiotics are combined with vancomycin or with each other. Red man syndrome is also magnified in patients receiving vancomycin and opioid analgesics, muscle relaxants, or contrast dye because these drugs can also stimulate histamine release.

Monday, June 4, 2012

Ice test - Poor man's test for Myasthenia Gravia 

 Most of the Myasthenia patients along with other symptoms of weakness usually exhibits ptosis. While at bedside place an ice cube over eye lids for 2 minutes. Cooling improves neuromuscular transmission. Resolution of ptosis with cooling is a positive test for Myasthenia Gravis and reported upto 80% reliable to diagnose ocular myasthenia.

Sunday, June 3, 2012

Q: What is the best way to follow on Amiodarone overdose? 

 Answer: Follow serial QT duration 

 Surprisingly, Overdose with amiodarone is usually benign as it is very poorly and variably absorbed. But all such patients should be admitted to ICU/CCU for close observation and serial EKGs. On EKG, Amiodarone leads to a prolonged QT interval due to its blocking of repolarising of. potassium channel. The QT duration is the best indicator of the extent of potassium channel blockade.

Saturday, June 2, 2012

Q: 42 year male with no previous history known is brought to ER with mental status change, fever and nuchal rigidity. CT scan is not much of information. ER doc performed lumbar punture and transferred patient to ICU. You get STAT call from lab that there is a spiderweb clot in the collected CSF. What does it mean?


Answer: A spiderweb clot in the collected CSF is characteristic of TB meningitis though not always present. 

The CSF usually has a high protein, low glucose and a increase lymphocytes. Acid-fast bacilli commonly grown in culture but the culture of TB from CSF takes about two weeks, and therefore the majority of patients with TB meningitis are started on treatment before the diagnosis is confirmed.

Friday, June 1, 2012


Q: What could be the ocular side effects of Amiodarone?




Answer:








Most side effects are due to Amiodarone intracytoplasmic lamellar deposits in the cornea, lens, retina, and optic nerve.


  • Colored rings around lights.
  • Corneal epithelial opacities resembling a cat's whiskers
  • Lens opacity
  • Retinopathy (rare)
  • Optic neuropathy


Ocular side effects of amiodarone - Surv Ophthalmol. 1998 Jan-Feb;42(4):360-6.