Q: Why its called Drug "eluting" stent?

Answer: Drug "eluting" stents refers to metal stents that elute (slowly released from stent) a drug designed to limit the growth of neointimal scar tissue. It further reduces the likelihood of stent restenosis. (see video below). Most commonly used drugs are sirolimus and paclitaxel. In last few years, everolimus has also gained popularity.

Q: What is May-Thurner syndrome?

Answer: May-Thurner syndrome is the compression of the left iliac vein by the right iliac artery. It is a major risk factor for severe DVT. It is an anatomical variant, and may require stent as a treatment.

Vertebral Artery Dissection

Q: How to perform oculocephalic and oculovestibular reflex testing as one of the determinant of brain death?

Answer: 

Oculocephalic reflex: First of call ensure the integrity of the cervical spine. Rotate briskly the head horizontally and vertically. There should be no movement of the eyes relative to head movement.

The oculovestibular reflex (caloric testing): First confirm the patency of the external auditory canal.  Elevate the head to 30 degrees. Irrigate each external auditory canal with approximately 50 ml of ice water. Movement of the eyes should be absent during 1 minute of observation. Both sides should be tested, with an interval of several minutes.

Q: What is Paradoxical CNS acidosis?

Answer: When Bicarbonate (HCO3) is infused, CO2 enters the blood brain barrier and forms carbonic acid. Clinical significance remains controversial.

Q: Which position is best to perform pericardiocentesis?


Answer: 30 to 45 degree

Semirecumbent position at a 30- to 45-degree angle brings the heart closer to the anterior chest wall. Some recommends upto 60 degree too.

Double lumen endotracheal tubes

Q: At what level of CPK, you should be vigilant in preventing ARF (Acute Renal Failure), mostly with IVF as mainstay of treatment?

Answer: 6,000 IU/L

Acute Renal Failure develops in almost 40% of patients with rhabdomyolysis. Precipitation of myoglobin and uric acid crystals within renal tubules along with decreased glomerular perfusion may cause acute tubular necrosis (ATN). As low as CPK level around 6000 IU/L, ATN may strike the patient.



Reference:

Ward MM. - Factors predictive of acute renal failure in rhabdomyolysis. Arch Intern Med. Jul 1988;148(7):1553-7.

A note on Methylnaltrexone

Subcutaneous methylnaltrexone (Relistor) rapidly induce laxation in patients with opioid-induced constipation. The major advantage is - the treatment usually does not affect central analgesia or precipitate opioid withdrawal. It cannot cross the blood–brain barrier, and so has antagonist effects throughout the body, counteracting effects such as itching and constipation, but without affecting opioid effects in the brain such as analgesia.

Reference:

Jay Thomas, M.D., Ph.D., Sloan Karver, M.D., Gail Austin Cooney, M.D., Bruce H. Chamberlain, M.D., Charles Kevin Watt, D.O., Neal E. Slatkin, M.D., Nancy Stambler, M.S., Alton B. Kremer, M.D., Ph.D., and Robert J. Israel, M.D. - Methylnaltrexone for Opioid-Induced Constipation in Advanced Illness - N Engl J Med 2008; 358:2332-2343 - May 29, 2008

EKOS

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Q:  52 year old female was started on LMWH (low molecular weight heparin) after Right knee replacement. Patient just before discharge complaint of left calf pain and diagnosed with DVT. Patient also noticed to dropped her platelet counts from 256 K/uL to 52 K/ul- and there was a high suspicion of HIT (Heparin induced thrombocytopenia). Patient was started on Argatroban. Your next  step would be to

A) Continue Lovenox till lab confirms the diagnosis of HIT

B) start warfarin for oral transition to anticoagulation

C) Insert IVC filter to prevent PE

D) Discharge patient home on Fondaparinux (arixtra)

E) Continue Argatroban with monitoring of PTT

Answer:  E

HIT is a clinically diagnosis. If clinical suspicion is high, management should be started without waiting for lab results. All Heparin related agents should be discontinued immediately (A is wrong).

Warfarin should not be started till Platelet count is 150 K/ul to prevent warfarin related necrosis. (B is wrong)

IVC filter is not indicated and usually should not be inserted to avoid further complications with thrombus. With Argatroban, patient is already protected for PE (C is wrong)

Patient is too sick to send home with diagnosis of HIT-T (D is wrong)

Q:  How long cells stay viable after BAL (Broncho-Alveolar lavage)?

Answer: About 4 hours

The cells remain viable in BAL fluid for up to 4 hours if stored around 25°C. BAL fluid can be transported at room temperature to lab if processing will occur in less than 1 hour, otherwise it should be transported in ice.

Q:  What is the proper way of preparing skin site for drawing peripheral blood culture?

Answer:  Vigorously cleanse the skin over the venipuncture site in a circle approximately 5 cm in diameter with 70%alcohol. Scrubbing should continue for 30 seconds. Starting in the centre of the circle, apply 10% povidine iodine (betadine) in ever widening circles until the entire circle is saturated with iodine*. Leave the iodine (or chlorhexidine) on the venipuncture site to act for 60 seconds.  Do not touch the venipuncture site after preparation and prior to phlebotomy.

*Chlorhexidine swabs which are 2% chlorhexidine Gluconate and 70% Isoporpyl Alcohol can be used in place of iodine.  

Q:  What advantage Linezolid has over Vancomycin in MRSA pneumonia?

Answer:  Penetration of linezolid into bronchial fluids is much higher than that of vancomycin. Also, linezolid has high bioavailability and allows easy switching to oral therapy. Moreover, It does not require any adjustment in kidney dysfunction. But, high cost of the drug still makes vancomycin a preferred choice over linezolid.

Q:  28 year old male is started on Levetiracetam (Keppra) in ICU for new onset seizure. Patient developed generalized mild rash all over the body after 3rd dose. What should be the next step? (choose one best answer)

A) Add anti-histamine with each dose 

B) Add Steroid

C) discontinue Keppra

D) Switch IV formulation to oral

E) Add Pyridoxine (Vitamin B6)

Answer: C

1 out of 3000 patients on Keppra may develop Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN). Recommendation is to discontinue Keppra upon signs of any unexplained rash. Ideally, Keppra should not be resumed and alternative drug should be considered. Pyridoxine (vitamin B6) is said to curtail some of the psychiatric symptoms arising from  use of Levetiracetam (Keppra).

Q: What is the next level of treatment in methemoglobinemia, if Methylene blue  fails?

Answer: Exchange transfusion

Methylene blue is the primary and emergent treatment for symptomatic methemoglobinemia. It should be remembered that Methylene Blue cannot be used in patients with G6PD deficiency. Exchange transfusion should be considered for patients who do not respond to methylene blue or have G6PD- deficiency.

IVC Ultrasound for Fluid Responsiveness

Link: http://youtu.be/ndcJ4DjmWVY

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Q: Which blood draw is preferred for lactic acid draw? 

Answer: Arterial

Lactate level differs substantially between arterial and venous levels. The arterial level is more representative for this purpose. Normal lactate level from venous blood draw is 0.5 to 2.2 mmol/L, and from arterial blood draw is 0.5 to 1.6 mmol/L.

Thrombolysis in stable PE

 Meta-analysis was done to determine mortality benefits and bleeding risks associated with thrombolytic therapy compared with anticoagulation in acute pulmonary embolism, including the subset of hemodynamically stable patients with right ventricular dysfunction (intermediate-risk pulmonary embolism).

Study Selection  Eligible studies were randomized clinical trials comparing thrombolytic therapy vs anticoagulant therapy in pulmonary embolism patients. Sixteen trials comprising 2115 individuals were identified. Eight trials comprising 1775 patients specified inclusion of patients with intermediate-risk pulmonary embolism.

Outcomes  

• Primary outcomes were all-cause mortality and major bleeding.
• Secondary outcomes were risk of recurrent embolism and intracranial hemorrhage (ICH).

Results  

• Use of thrombolytics was associated with lower all-cause mortality ( 2.17% vs 3.89% ] 
•  greater risks of major bleeding 9.24%  vs 3.42%
•  ICH  1.46% vs 0.19%
• Major bleeding was not significantly increased in patients 65 years and younger 
• Thrombolysis was associated with a lower risk of recurrent pulmonary embolism ( 1.17%  vs 3.04%).

Conclusions  Among patients with pulmonary embolism, including those who were hemodynamically stable with right ventricular dysfunction, thrombolytic therapy was associated with lower rates of all-cause mortality but increased risks of major bleeding and ICH. However, findings may not apply to patients with pulmonary embolism who are hemodynamically stable without right ventricular dysfunction.

Thrombolysis for Pulmonary Embolism and Risk of All-Cause Mortality, Major Bleeding, and Intracranial Hemorrhage A Meta-analysis - Saurav Chatterjee; Anasua Chakraborty; Ido Weinberg; Mitul Kadakia; Robert L. Wilensky; Partha Sardar; Dharam J. Kumbhani, MD,; Debabrata Mukherjee, MD, MS5; Michael R. Jaff; Jay Giri, MD - JAMA. 2014;311(23):2414-2421

Q: IV magnesium is usually not indicated when hyperkalemia exists except in one condition?

Answer: Magnesium can potentiate myocardial conduction abnormalities and therefore is probably contraindicated in patients with hyperkalaemia. However, in hyperkalaemia  associated with digoxin poisoning, intravenous magnesium sulphate may eliminate refractory ventricular tachycardia and decrease the serum potassium.

Q: What amount of Coronary Air Embolism can be fatal?

Answer: Sounds strange but as low as 0.5 ml of air in coronary circulation can cause cardiac arrest.

Q: Why Heparin is added to Prothrombin Complex Concentrates (PCC)?

Answer:  PCC are produced by ion-exchange chromatography from the cryoprecipitate supernatant of large plasma pools. It may contain either three-factor (i.e., factors II, IX and X) or four-factor (i.e., factors II, VII, IX and X) concentrates with a final overall clotting factor concentration approximately 25 times higher than in normal plasma. To prevent activation of these factors, most PCC contain heparin. 

                             

References:

1. Hellstern P. Production and composition of prothrombin complex concentrates: correlation between composition and therapeutic efficiency. Thromb Res. 1999;95:S7–12.

2. Schulman S, Bijsterveld NR. Anticoagulants and their reversal. Transfus Med Rev. 2007;21:37–48.

Q: 54 year old male on Pradaxa (Dabigatran) for Atrial fibrillation is now admitted to ICU from OR as patient continue to bleed generally from Incision as well as orifices, after emergent abdominal hernia repair. Patient was re-explored in OR twice to rule out any surgical bleed. Patient received multiple blood products including FFP, PCC, Platelets and 10 units of pRBC. What else could be done to stop bleeding secondary to Pradaxa?
 

Answer: Trial of Dialysis

All new oral Direct Thombin Inhibitors  (DTIs) can cause problems in OR and ICU as they don't have any effective reversal. Pradaxa is mostly excreted via Kidney and some literature supports success in reversing bleeding with dialysis. In contrast, Xeralto (Rivaroxaban) is highly protein bound and major metabolic pathway is via liver, and cannot be reversed with dialysis.

References:

Stangier J, Rathgen K, Stahle H, Mazur D. Influence of renal impairment on the pharmacokinetics and pharmacodynamics of oral dabigatran etexilate: an open-label, parallel-group, single-centre study. Clin Pharmacokinet. 2010;49:259-268. 

Wanek MR, Horn ET, Elapavaluru S, Baroody SC, Sokos G. Safe use of hemodialysis for dabigatran removal before cardiac surgery. Ann Pharmacother. 2012;46:e21.

Q: Why sotalol is preferred over other Beta-Blockers for prevention of V. Tach. and V.fib.?

Answer: Due to its Dual action.

Sotalol is a non-selective β-blocker that also exhibits Class III antiarrhythmic properties by its inhibition of potassium channels. Because of this dual action, Sotalol prolongs both the PR interval and the QT interval. Sotalol is often preferred over other β-blockers as prevention and treatment for both ventricular fibrillation and ventricular tachycardia.

Q: Which drug is found to be associated with Vasoplegia Syndrome in post cardiac surgery patients?

Answer: ACE inhibitors and ARBs

Though there is a weak evidence, but many reports have suggested that preoperative administration of ACEI/ARBs in patients undergoing cardiac surgery contributes to lowering of SVR (vasoplegia syndrome) postoperatively. It is also suggested, if possible to hold ACEI/ARBs 24 hours before cardiac surgery to avoid postoperative vasodilation.


References:

Lee YK, 

Na SW, 

Kwak YL, 

Nam SB - 

Effect of pre-operative angiotensin-converting enzyme inhibitors on haemodynamic parameters and vasoconstrictor requirements in patients undergoing off-pump coronary artery bypass surgery. J Int Med Res 2005;33:693-702.

1. 1. 
      
2. Devbhandari MP, 
3. Balasubramanian SK, 
4. Codispoti M, 
5. Nzewi OC, 
6. Prasad SU

.Preoperative angiotensin-converting enzyme inhibition can cause severe post CPB vasodilation – current UK opinion. Asian Cardiovasc Thorac Ann 2004;12:346-349.

1. 1. 
      
2. Bertrand M, 
3. Godet G, 
4. Meersschaert K, 
5. Brun L, 
6. Salcedo E, 
7. Coriat P

. Should the angiotensin II antagonists be discontinued before surgery? Anesth Analg2001;92:26-30.

1. 1. 
      
2. Pigott DW, 
3. Nagle C, 
4. Allman K, 
5. Westaby S, 
6. Evans RD

. Effect of omitting regular ACE inhibitor medication before cardiac surgery on haemodynamic variables and vasoactive drug requirements. Br J Anaesth 1999;83:715-720.

1. 1. 
      
2. Licker M, 
3. Neidhart P, 
4. Lustenberger S, 
5. Valloton MB, 
6. Kalonji T, 
7. Fathi M, 
8. Morel DR

.Long-term angiotensin-converting enzyme inhibitor treatment attenuates adrenergic responsiveness without altering hemodynamic control in patients undergoing cardiac surgery. Anesthesiology 1996;84:789-800.

1. 1. 
      
2. Tuman KJ, 
3. McCarthy RJ, 
4. O'Connor CJ, 
5. Holm WE, 
6. Ivankovich AD

. Angiotensin-converting enzyme inhibitors increase vasoconstrictor requirements after cardiopulmonary bypass. Anesth Analg 1995;80:473-479.

A note on Coronary Perfusion Pressure

Coronary Perfusion Pressure is a very under appreciated concept in ICUs. Coronary perfusion pressure (CPP) refers to the pressure gradient that drives coronary blood pressure. It is the difference between the aortic diastolic pressure and left ventricular end-diastolic pressure.

During cardiac arrest, CPP is one of the most important variables associated with the likelihood of return of spontaneous circulation (ROSC). A CPP of at least 15 mmHg is considered to be necessary for ROSC.

CPP = ADP - LVEDP

It signifies the proper filling pressure and importance of arterial diastolic pressure.

Selected Cephalosporins Can Be Used in Patients with a History of Penicillin Allergy

A widely circulated misconception has been the tale that there is a 10% cross-allergy risk between penicillin and all cephalosporins. Not so, according to a recent literature review. It seems that while some cephalosporins – cephalothin, cephalexin, cefadroxil, and cefazolin – have a significant risk of cross-allergy with penicillin, others do not. The safer drugs to use in a setting of a history of penicillin allergy are: cefprozil, cefuroxime, cefpodoxime, ceftazidime, and ceftriaxone.

Given that there are legions of patients that carry the label “penicillin-allergic,” however valid or erroneous this designation might be, knowing that certain cephalosporins can be used in these patients will be helpful in daily practice.

Reference

1. Pichichero ME. Cephalosporins can be prescribed safely for penicillin-allergic patients. J Fam Pract. 2006; 55(2): 106–107.

Q: What is the dose of 23.4% Saline bolus in refractory Increased Intra-Cranial Pressure (ICP)

Answer:  30 ml

30 ml of an intravenous bolus administration of 23.4% hypertonic saline reduced ICP and augmented CPP for up to 3 hours in patients with intractable elevations in ICP from diverse origins that were refractory to all conventional therapeutic modalities including hyperventilation, mannitol and barbiturates. 

References:

1. Suarez JI, Qureshi AI, Bhardwaj A, Williams MA, Schnitzer MS, Mirski M, et al: Treatment of refractory intracranial hypertension with 23.4% saline. Crit Care Med 26:1118–1122, 1998

2. Ware ML, Nemani VM, Meeker M, Lee C, Morabito DJ, Man ley GT: Effects of 23.4% sodium chloride solution in reducing intracranial pressure in patients with traumatic brain injury: a preliminary study. Neurosurgery 57:727–736, 2005