Friday, February 28, 2020

lasix ototoxicity

Q: 53 year old male has been started on furosemide drip for oliguric renal insufficiency with gradually escalating dose. On 3rd day of infusion patient c/o hearing disturbances. What is the mechanism of action of loop diuretics to cause ototoxicity?

Answer:  In the loop of Henle part of nephrons, where transport is mediated by a Na-K-2Cl cotransporter, it gets inhibited by loop diuretics. Interestingly, a secretory isoform of this cotransporter is also present in the inner ear and plays a role in the composition of endolymph. Inactivation of this cotransporter leads to reduced endolymph secretion, and so to structural damage to the inner ear, deafness, and imbalance. 

 Due to similar action, furosemide has been used to diagnose Meniere disease.




1. Delpire E, Lu J, England R, et al. Deafness and imbalance associated with inactivation of the secretory Na-K-2Cl co-transporter. Nat Genet 1999; 22:192. 

2.  Seo T, Node M, Yukimasa A, Sakagami M. Furosemide loading vestibular evoked myogenic potential for unilateral Ménière's disease. Otol Neurotol 2003; 24:283.

Thursday, February 27, 2020

Abcess in perforated appendectomy

Q: In patients who have perforated appendicitis with abscess formation. Which of the following approach is preferred? 

A) Percutaneous abscess drainage 
B) Immediate surgical exploration

Answer: A

In perforated acute appendicitis with abscess formation computed tomography (CT) or ultrasound (US)-guided drainage can be performed either percutaneously or transrectally. This approach seems to result in fewer complications and a shorter length of stay (LOS). Also, it allows inflammation to subside before appendectomy, and fewer chances of extended bowel resection.



1. Oliak D, Yamini D, Udani VM, et al. Initial nonoperative management for periappendiceal abscess. Dis Colon Rectum 2001; 44:936. 

2. Gee D, Babineau TJ. The optimal management of adult patients presenting with appendiceal abscess: "conservative" vs immediate operative management. Curr Surg 2004; 61:524. 

3. Brown CV, Abrishami M, Muller M, Velmahos GC. Appendiceal abscess: immediate operation or percutaneous drainage? Am Surg 2003; 69:829.

Wednesday, February 26, 2020

Ca/Cr clearance ratio

Q: 34 year old female is admitted to ICU with hypercalcemia of 13.7 mg/dL. Endocrinology requested Ca/Cr clearance ratio. What's the significance of a Ca/Cr clearance ratio?

Answer: It differentiate between Primary hyperparathyroidism (PHPT) and familial hypocalciuric hypercalcemia (FHH) 

 A calcium/creatinine (Ca/Cr) clearance ratio is calculated from 24-hour urinary calcium and creatinine and total serum calcium and creatinine. The formula is

Ca/Cr clearance ratio = [24-hour urine Ca x serum Cr] ÷ [serum Ca x 24-hour urine Cr]

A value below 0.01 in a vitamin D-replete individual is highly suggestive of FHH, and a value usually above 0.02 suggests PHPT 

A Ca/Cr clearance ratio 0.02 essentially excluded FHH. 


 Marx SJ. Letter to the editor: Distinguishing typical primary hyperparathyroidism from familial hypocalciuric hypercalcemia by using an index of urinary calcium. J Clin Endocrinol Metab 2015; 100:L29.

Tuesday, February 25, 2020

metronidazole and CNS

Q: 32 year old male who is on long term high dose metronidazole for multidrug-resistant tuberculosis developed seizures and has been admitted to ICU. Which of the following diagnostic workup may confirm Metronidazole induced seizure? 

A) Magnetic Resonance Imaging (MRI) 
B) Lumbar Puncture (LP) 

 Answer: A

Metronidazole may cause nervous system toxicity with manifestations of seizures, peripheral neuropathy, dizziness, vertigo, ataxia, confusion, encephalopathy, irritability, weakness, insomnia, headache, and tremors. This is a dose dependent side effect. MRI in those patients may show bilateral symmetric T2 hyperintense lesions. Fortunately, these side effects and MRI findings are reversible. 

LP may show metronidazole level but it just suggest expected penetration  in nervous system but not the reason for toxicity. Metronidazole penetrates the blood-brain barrier and cerebrospinal fluid (CSF) levels approximate 45 percent of corresponding serum concentrations. Metronidazole has excellent penetration into brain abscesses.




1. Kusumi RK, Plouffe JF, Wyatt RH, Fass RJ. Central nervous system toxicity associated with metronidazole therapy. Ann Intern Med 1980; 93:59.

2. Farmakiotis D, Zeluff B. IMAGES IN CLINICAL MEDICINE. Metronidazole-Associated Encephalopathy. N Engl J Med 2016; 374:1465.

3. Kim E, Na DG, Kim EY, et al. MR imaging of metronidazole-induced encephalopathy: lesion distribution and diffusion-weighted imaging findings. AJNR Am J Neuroradiol 2007; 28:1652.

4. Lefkowitz A, Shadowitz S. Reversible cerebellar neurotoxicity induced by metronidazole. CMAJ 2018; 190:E961.

5. Jokipii AM, Myllylä VV, Hokkanen E, Jokipii L. Penetration of the blood brain barrier by metronidazole and tinidazole. J Antimicrob Chemother 1977; 3:239.

Monday, February 24, 2020


Q: "Routine aspirin (ASA) therapy in patients with congestive heart failure (CHF) may not be beneficial and actually may be harmful." (select one)

A) True
B) False

Answer: A

There is strong literature available to suggest that ASA may not be of any benefit rather harmful in CHF patients. Some of the major trials in this regard including WASH, WATCH and WARCEF trials have been given in the reference section 1,2, 3. 

 Various explanations have been sought for this paradox. It might be due to the fact that ASA may attenuate some effects of angiotensin-converting enzyme (ACE) inhibitors. Also, ASA may interfere with the positive effects of beta-blockers in patients with HFrEF.



1. Cleland JG, Findlay I, Jafri S, et al. The Warfarin/Aspirin Study in Heart failure (WASH): a randomized trial comparing antithrombotic strategies for patients with heart failure. Am Heart J 2004; 148:157. 

2. Massie BM, Collins JF, Ammon SE, et al. Randomized trial of warfarin, aspirin, and clopidogrel in patients with chronic heart failure: the Warfarin and Antiplatelet Therapy in Chronic Heart Failure (WATCH) trial. Circulation 2009; 119:1616. 

3. Homma S, Thompson JL, Pullicino PM, et al. Warfarin and aspirin in patients with heart failure and sinus rhythm. N Engl J Med 2012; 366:1859. 

4. Madelaire C, Gislason G, Kristensen SL, et al. Low-Dose Aspirin in Heart Failure Not Complicated by Atrial Fibrillation: A Nationwide Propensity-Matched Study. JACC Heart Fail 2018; 6:156.

5. Lindenfeld J, Robertson AD, Lowes BD, et al. Aspirin impairs reverse myocardial remodeling in patients with heart failure treated with beta-blockers. J Am Coll Cardiol 2001; 38:1950.

Sunday, February 23, 2020

febrile seizure

Q: The main determinant of febrile seizures is? (select one) 

A) the maximum height of a fever 
B) the rate of rise of fever

Answer: A

Although there is some disagreement among experts most studies show that maximum height of the fever instead of the rate of rising is the main risk of febrile seizures. Said that there are many factors that contribute to the clinical condition including patient's seizure threshold, underlying infection, co-morbidities, medications, age, and water and electrolyte imbalances.




MILLICHAP JG. Studies in febrile seizures. I. Height of body temperature as a measure of the febrile-seizure threshold. Pediatrics 1959; 23:76. 

 Berg AT, Shinnar S, Shapiro ED, et al. Risk factors for a first febrile seizure: a matched case-control study. Epilepsia 1995; 36:334.

Saturday, February 22, 2020

PFO and migraine

Case: 38-year-old female is admitted to ICU third time with a severe headache. All extensive neurological diagnostic workup turned out to be negative again alike last 2 previous admissions. Neurology service recommended closure of benign Patent Foramen Ovale (PFO) as a treatment for migraine.

Answer: There are some anecdotal reports that closure of PFO may help in decreasing the intensity of migraines. There is no strong evidence in this regard (multiple references below show mixed results). Said that, in patients who require frequent hospital admissions, and if symptoms become life-debilitating, this may be of consideration.  Risks and benefits should be discussed with the patient in detail before pursuing this invasive procedure. The etiology behind this correlation is not fully understood.




1. Dowson A, Mullen MJ, Peatfield R, et al. Migraine Intervention With STARFlex Technology (MIST) trial: a prospective, multicenter, double-blind, sham-controlled trial to evaluate the effectiveness of patent foramen ovale closure with STARFlex septal repair implant to resolve refractory migraine headache. Circulation 2008; 117:1397. 

2. Mattle HP, Evers S, Hildick-Smith D, et al. Percutaneous closure of patent foramen ovale in migraine with aura, a randomized controlled trial. Eur Heart J 2016; 37:2029. 

3. Schwedt TJ, Demaerschalk BM, Dodick DW. Patent foramen ovale and migraine: a quantitative systematic review. Cephalalgia 2008; 28:531. 

4. Schwerzmann M, Wiher S, Nedeltchev K, et al. Percutaneous closure of patent foramen ovale reduces the frequency of migraine attacks. Neurology 2004; 62:1399. 

5. Post MC, Thijs V, Herroelen L, Budts WI. Closure of a patent foramen ovale is associated with a decrease in prevalence of migraine. Neurology 2004; 62:1439. 

6. Reisman M, Christofferson RD, Jesurum J, et al. Migraine headache relief after transcatheter closure of patent foramen ovale. J Am Coll Cardiol 2005; 45:493. 

7.  Anzola GP, Frisoni GB, Morandi E, et al. Shunt-associated migraine responds favorably to atrial septal repair: a case-control study. Stroke 2006; 37:430. 

8. Yankovsky AE, Kuritzky A. Transformation into daily migraine with aura following transcutaneous atrial septal defect closure. Headache 2003; 43:496.

Friday, February 21, 2020

"non-malignant" cases of central airway obstruction

Q: Name at least 5 "non-malignant" causes of central airway obstruction (CAO)? 

Answer:  Commonly, malignancy and foreign bodies are the two major causes come to mind as CAO. But there are many other etiologies which can lead to CAO, including
  • tracheobronchomalacia
  • tracheal strictures (mostly due to endotracheal or tracheostomy tubes)
  •  anastomotic stenoses following a lung transplant
  • airway papillomas 
  • endobronchial hamartomas
  • vascular rings/congenital heart diseases(eg double aortic arch which causes extrinsic compression or malacia) 
  • endobronchial infections (eg,  tuberculosis, or histoplasmosis)
  • laryngoceles
  • airway hematoma due to trauma 
  • any other extrinsic compression (eg goiter, or hematoma after central line attempt)
  • any inflammatory pathology


1. Ernst A, Feller-Kopman D, Becker HD, Mehta AC. Central airway obstruction. Am J Respir Crit Care Med 2004; 169:1278. 

2. Blackledge FA, Anand VK. Tracheobronchial extension of recurrent respiratory papillomatosis. Ann Otol Rhinol Laryngol 2000; 109:812. 

3. Cosío BG, Villena V, Echave-Sustaeta J, et al. Endobronchial hamartoma. Chest 2002; 122:202. 

4. An HS, Choi EY, Kwon BS, et al. Airway compression in children with congenital heart disease evaluated using computed tomography. Ann Thorac Surg 2013; 96:2192. 

5. Hoheisel G, Chan BK, Chan CH, et al. Endobronchial tuberculosis: diagnostic features and therapeutic outcome. Respir Med 1994; 88:593. 

6. Kaya G, Ladas A, Howlett D. Laryngocele causing airway obstruction. BMJ 2016; 352:i1368. 

7. Silva FS. Neck haematoma and airway obstruction in a patient with goitre: complication of internal jugular vein cannulation. Acta Anaesthesiol Scand 2003; 47:626.

Thursday, February 20, 2020

Amio and corneal deposits

Q: 58 year old male with long term atrial fibrillation (A.fib.) and known Amiodarone (Amio) toxicity is admitted to ICU with A.fib. with Rapid Ventricular Rate (RVR). Cardiology wrote for Amiodarone bolus but ICU intern is worried about already present corneal microdeposits, a sign of Amiodarone toxicity. Corneal microdeposits with Amiodarone treatment is? (select one) 

A) Reversible 
B) Irreversible 

Answer: A

Long term Amio may cause corneal microdeposits and/or lenticular opacities. These are not cellular deposits rather the secretion of amiodarone by the lacrimal gland results in its accumulation on the corneal surface. On the ophthalmic exam, they are usually visible at the juncture of the lower 1/3 and upper 2/3 of the cornea as a brownish whorl resembling as a cat's whiskers. These microdeposits are dose-dependent and as they are deposits from lacrimation, they are reversible with the stoppage of the drug, though they hamper visual acuity at night. Also, they may cause photophobia and blurred vision. 

Pertaining to above question, microdeposits is not a contraindication to further amiodarone therapy.




1. Vorperian VR, Havighurst TC, Miller S, January CT. Adverse effects of low dose amiodarone: a meta-analysis. J Am Coll Cardiol 1997; 30:791.

2. Mäntyjärvi M, Tuppurainen K, Ikäheimo K. Ocular side effects of amiodarone. Surv Ophthalmol 1998; 42:360.

Wednesday, February 19, 2020


Q: 64-year-old female is admitted to ICU with cough, shortness of breath, fever, and septic like picture.  CT scan of the chest done in ED ruled out any underlying pulmonary embolism but showed concern for cryptogenic organizing pneumonia (COP). Which of the following is the least likely symptom of COP?

A) Nonproductive cough 

B) Dyspnea 
C) Malaise 
D) Weight loss 
E) Hemoptysis


Presentation of COP is sometimes similar to community-acquired pneumonia (CAP) with a short duration of symptoms of few weeks only. And, the only clue for the diagnosis of COP is a lack of response to empiric antibiotics! 

The classic presentation is of a patient in the fifth or sixth decade of life with persistent nonproductive cough, dyspnea, fever, malaise, and weight loss of greater than 10 pounds. Hemoptysis is rarely present in COP.



1. Cordier JF. Cryptogenic organising pneumonia. Eur Respir J 2006; 28:422.

2. Zhou Y, Wang L, Huang M, et al. A long-term retrospective study of patients with biopsy-proven cryptogenic organizing pneumonia. Chron Respir Dis 2019; 16:1479973119853829.

Tuesday, February 18, 2020

Acyclovir in ESRD

Q: 63 year old male with End Stage Renal Disease (ESRD) is admitted to ICU with herpes pneumonitis. What precaution should be taken while prescribing Acyclovir?

Answer: To dose after hemodialysis (HD) session

Almost 50-60% of acyclovir is lost in hemodialysis. In ICU, things get trickier when ESRD patients are on continuous renal replacement therapy (CRRT). Acyclovir clearance depends on various factors like filter type and flow rate. Response to acyclovir is more guided by clinical response and side effects, than targeted trough level. Help from pharmacy service should be sought in such situations.




1. Aronoff GR, Bennett WM, Berns JS, et al. Drug Prescribing in Renal Failure: Dosing Guidelines for Adults and Children. 5th ed. Philadelphia, PA: American College of Physicians; 2007. 

2. Heintz BH, Matzke GR, Dager WE. Antimicrobial dosing concepts and recommendations for critically ill adult patients receiving continuous renal replacement therapy or intermittent hemodialysis. Pharmacotherapy. 2009;29(5):562-577. doi: 10.1592/phco.29.5.562.

Monday, February 17, 2020


Q: What is the right step just prior to obtaining the Rapid Shallow Breathing Index (RSBI)? 


RSBI is the ratio of respiratory frequency/rate to tidal volume (f/VT). It is not a perfect but a good indicator of a patient's successful liberation from the ventilator. It has been suggested that a reliable RSBI can be obtained by measuring respiratory rate and tidal volume, using a hand-held spirometer attached to the endotracheal tube (ETT), while a patient is breathing room air for one minute without any ventilator assistanceAll new models of ventilators are equipped to measure RSBI.



Yang KL, Tobin MJ. A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. N Engl J Med 1991; 324:1445.

Sunday, February 16, 2020

washed pRBC

Case:  62 year old male with Chronic Kidney Disease (CKD)-5 is admitted to ICU with active gastro-intestinal bleed (GIB). Hemoglobin (Hb) is reported at 6.2 g /dL and Potassium (K) level is reported at 5.9 meq/L. What strategies can be applied to reduce the risk of hyperkalemia in this CKD-5 patient with blood transfusion, who is not on hemodialysis yet?

Answer: Potassium overload can be a concern with ongoing pRBC transfusion particularly in renal patients. There are two strategies which may help to reduce this risk

  • fresher units, or 
  • washed red cells
Many times it is difficult for blood bank to supply fresher units of pRBCs. Washing of pRBC is done in an automated system with the use of normal saline immediately before transfusion. Washed pRBCs can be preserved for 4 hours on shelf/bedside at 20 to 24°C. Longer preservation can be done for 24 hours if stored at 1 to 6°C.




1. Raza S, Ali Baig M, Chang C, et al. A prospective study on red blood cell transfusion related hyperkalemia in critically ill patients. J Clin Med Res. 2015;7(6):417–421. doi:10.14740/jocmr2123w 

2. Bansal I, Calhoun BW, Joseph C, Pothiawala M, Baron BW. A comparative study of reducing the extracellular potassium concentration in red blood cells by washing and by reduction of additive solution. Transfusion. 2007 Feb;47(2):248-50.

Saturday, February 15, 2020

Succinylcholine and heart rhythm

Q; Succinylcholine (Sch) tends to do? (Select one)

A) Bradycardia
B) Tachycardia

Answer: A

The objective of the above question is to emphasize to clinicians that atropine should be kept in vicinity whenever Sch is administrated. The initial metabolite of SCh, named succinylmonocholine sensitizes the cardiac muscarinic receptors in the sinus node, and may lead to bradycardia, particularly when dose of SCh is repeated. Some experts suggests prophylactic use of atropine in patients who are already on bradycardic or if dose is repeated, but this practice is controversial.




Jeevendra Martyn; Marcel E. Durieux, Succinylcholine: New Insights into Mechanisms of Action of an Old Drug Anesthesiology 4 2006, Vol.104, 633-634. doi:

Friday, February 14, 2020

Proteinuria in preeclampsia

Q: According to the American College of Obstetricians and Gynecologists proteinuria is required as an essential criterion for the diagnosis of preeclampsia?

A) True
B) False

Answer: B

In 2013, the American College of Obstetricians and Gynecologists made major changes towards the diagnosis of preeclampsia. It simplified the diagnosis. Hypertension plus signs of significant end-organ dysfunction are sought as sufficient for the diagnosis of preeclampsia. 

Proteinuria which was once considered a hallmark criterion for the diagnosis of preeclampsia is no more required. Also, massive proteinuria i.e. 5 g/24 hours, and fetal growth restriction has been removed as possible features of severe preeclampsia.



1. ACOG Practice Bulletin No. 202: Gestational Hypertension and Preeclampsia. Obstet Gynecol 2019; 133:e1. 

2. Tranquilli AL, Dekker G, Magee L, et al. The classification, diagnosis and management of the hypertensive disorders of pregnancy: A revised statement from the ISSHP. Pregnancy Hypertens 2014; 4:97.

Thursday, February 13, 2020

fibers in nutrition

Q: What is the difference between gelatinous fibers and highly soluble fibers used to decrease diarrhea in ICU patients?


It is a common practice to add fiber with enteral nutrition in ICU patients who experience diarrhea. There are two major types of fibers
  • gelatinous fiber
  • highly soluble fiber 
Gelatinous fibers are effective but they are less soluble and tend to clog the feeding tube. The most commonly used gelatinous fiber is psyllium. To prevent this complication, highly soluble fibers have been utilized but they are not as effective, and in some cases may even make diarrhea worse due to their osmotic effect. The commonly used highly soluble fibers are guar gum, wheat dextrin, inulin, and fructooligosaccharides.




1. Hart GK, Dobb GJ. Effect of a fecal bulking agent on diarrhea during enteral feeding in the critically ill. JPEN J Parenter Enteral Nutr 1988; 12:465. 

2. Kamarul Zaman M, Chin KF, Rai V, Majid HA. Fiber and prebiotic supplementation in enteral nutrition: A systematic review and meta-analysis. World J Gastroenterol 2015; 21:5372. 

3.  Spapen H, Diltoer M, Van Malderen C, et al. Soluble fiber reduces the incidence of diarrhea in septic patients receiving total enteral nutrition: a prospective, double-blind, randomized, and controlled trial. Clin Nutr 2001; 20:301. 

4.  Rushdi TA, Pichard C, Khater YH. Control of diarrhea by fiber-enriched diet in ICU patients on enteral nutrition: a prospective randomized controlled trial. Clin Nutr 2004; 23:1344. 

5.  Taylor BE, McClave SA, Martindale RG, et al. Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient: Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.). Crit Care Med 2016; 44:390.

Wednesday, February 12, 2020


Q: Carvedilol should be used with high caution in? (select one)

A) End Stage renal disease
B) End stage liver disease

Answer: B

Carvedilol gets metabolized via liver, and should be used with high caution in severe hepatic disease. Serum concentrations may accumulate up to seven folds higher than in normal patients. 

Renal patients can take carvedilol without much adjustment as it is neither renally secreted nor get cleared by hemodialysis.




Satish Maharaj, Karan Seegobin, Julio Perez-Downes, Belinda Bajric, Simone Chang & Pramod Reddy Severe carvedilol toxicity without overdose – caution in cirrhosis Clinical Hypertension volume 23, Article number: 25 (2017)

Tuesday, February 11, 2020

PEEP in prone

Q: What is the implication of Positive End Expiratory Pressure (PEEP) in patients with a prone position?


The teaching point of this pearl is to emphasize the point that supraphysiologic applied PEEP (i.e.,>5) is usually nor helpful, rather may be harmful, in patients in prone position. 

In a regular ventilated patient who stays in the supine position, PEEP increases the blood flow to the dorsal portion of the lungs. It helps in maintaining a ventilation-perfusion (V/Q) mismatch. But when patients are put in a prone position, PEEP increases the blood flow to the ventral portion of the lungs which is out of proportion to the redistribution of ventilation, thereby exacerbates the V/Q mismatch.



Petersson J, Ax M, Frey J, et al. Positive end-expiratory pressure redistributes regional blood flow and ventilation differently in supine and prone humans. Anesthesiology 2010; 113:1361.

Monday, February 10, 2020

physiologic effects of severe metabolic acidosis

Q: What are the three physiologic hemodynamic effects of severe metabolic acidosis?

Answer: Infusion of bicarbonate is usually not recommended in metabolic acidosis unless PH goes below 7.1. Clinicians often used bicarbonate once PH is even below 7.3. This is not an evidence-based practice.  Said that bicarbonate may become a stabilizing agent as acidemia progressively gets worse. Once human PH falls below 7.1, it produces three physiologic effects
  • reduced left ventricular contractility 
  • arterial vasodilation, and 
  • impaired responsiveness to catecholamines


1. Kraut JA, Madias NE. Treatment of acute metabolic acidosis: a pathophysiologic approach. Nat Rev Nephrol 2012; 8:589. 

2. Marsh JD, Margolis TI, Kim D. Mechanism of diminished contractile response to catecholamines during acidosis. Am J Physiol 1988; 254:H20. 

3.  Orchard CH, Kentish JC. Effects of changes of pH on the contractile function of cardiac muscle. Am J Physiol 1990; 258:C967. 

4. Mathieu D, Neviere R, Billard V, et al. Effects of bicarbonate therapy on hemodynamics and tissue oxygenation in patients with lactic acidosis: a prospective, controlled clinical study. Crit Care Med 1991; 19:1352.

Sunday, February 9, 2020

PAC sample in FES

Q: A wedged sample of fat from pulmonary artery catheter (PAC) is more specific for diagnosis of Fat Embolism Syndrome (FES) than samples from bronchoalveolar lavage (BAL)? 

A) True 
B) False 

 Answer: B

Clinician should not place pulmonary artery catheter exclusively for the purpose of diagnosis of FES. Presence of fat from a wedged sample of pulmonary arterial blood is neither sensitive nor specific to diagnose FES.  
Also, there is no diagnostic criteria for fat analysis is available.

As a matter of fact, BAL samples with >30% of alveolar cells staining for neutral fat is found to be strongly associated with a clinical diagnosis of FES.




Mimoz O, Edouard A, Beydon L, Quillard J, Verra F, Fleury J, Bonnet F, Samii K. Contribution of bronchoalveolar lavage to the diagnosis of posttraumatic pulmonary fat embolism.Intensive Care Med. 1995; 21:973–980

Saturday, February 8, 2020

Diarrhea in pregnancy

Case: 32 year old female in the first trimester of pregnancy, who just returned from a Southeast Asian country is admitted to ICU with severe dysentery. Which of the following antibiotics would you choose? (select one)

 A) azithromycin 
 B) fluoroquinolone 

Answer: A

The objective of the above question is to emphasize the rising resistance of fluoroquinolone across the globe particularly in southeast Asian countries. Antibiotics are not indicated for mild travelers' diarrhea but in severe cases, it may require antibiotics. Azithromycin is preferred in severe dysentery, pregnancy, and children. The preferred dose is 1 gram in a single dose, or 500 mg daily for 3 days.

Note: A clue for the right answer in this question is pregnancy. All fluoroquinolones are contraindicated in children, adolescents, pregnant and breastfeeding women.




Riddle MS, Connor BA, Beeching NJ, et al. Guidelines for the prevention and treatment of travelers' diarrhea: a graded expert panel report. J Travel Med 2017; 24:S57.

Friday, February 7, 2020

Rounded atelactasis

Q: Rounded atelectasis usually points toward which disease?

Answer:  Previous asbestos exposure

Rounded atelectasis is seen on radiologic imagings and has been given a lot of names including folded lung, atelectatic pseudotumor, comet tail sign, and Blesovsky's syndrome. It is actually a subpleural mass with emanating swirl of vessels and bronchi that curve like a comet tail (also called vacuum cleaner effect) as they connect to the atelectatic lung parenchyma. Mostly their location is in the lower lobes, lingula, or right middle lobe. The subpleural mass of rounded atelectasis can be a pleural plaque, diffuse pleural thickening, existing or resolving pleural effusion, accompanying loss of volume in the adjacent lung, or adjacent accumulation of extrapleural fat.

Clinical significance: If the comet tail is not present with rounded atelectasis, the risk of a tumor is very high and calls for a biopsy. But if comet tail is characteristically present, the rounded atelectasis can be followed radiologically over years. They may get resolved and rarely grows.

Although asbestos exposure is most likely to be associated, rounded atelectasis can also be seen in pleural tuberculosis.




1. Stark P. Round atelectasis: another pulmonary pseudotumor. Am Rev Respir Dis 1982; 125:248. Partap VA. 

2. The comet tail sign. Radiology 1999; 213:553. 

3. Hanke R, Kretzschmar R. Round atelectasis. Semin Roentgenol 1980; 15:174. 

4.  Stathopoulos GT, Karamessini MT, Sotiriadi AE, Pastromas VG. Rounded atelectasis of the lung. Respir Med 2005; 99:615.

Thursday, February 6, 2020

30-30-30 rule in AAA

Q: What is the 30-30-30 minutes rule for intervention in a ruptured Abdominal Aortic Aneurysm (AAA)?

Answer:  There is a certain mortality benefit for patients in symptomatic, ruptured or impending rupture AAA, if they are in teaching hospitals where such cases presents in a large number. The Society for Vascular Surgery guidelines recommends a "door-to-intervention" time of less than 90 minutes. 30-30-30 minutes rule 

1. From first medical contact to diagnosis and decision to transfer 

2. Rapid transport to the experienced facility, and 
3. Evaluation by the vascular team to arterial access and vascular control by aortic occlusion. 

 On side note, patients transferred on the weekend are reported to have higher adjusted mortality.



1. Chaikof EL, Dalman RL, Eskandari MK, et al. The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm. J Vasc Surg 2018; 67:2. 

2.  Mell MW, Starnes BW, Kraiss LW, et al. Western Vascular Society guidelines for transfer of patients with ruptured abdominal aortic aneurysm. J Vasc Surg 2017; 65:603. 

3.  Karthikesalingam A, Holt PJ, Vidal-Diez A, et al. Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA. Lancet 2014; 383:963. 

4.  Cho JS, Kim JY, Rhee RY, et al. Contemporary results of open repair of ruptured abdominal aortoiliac aneurysms: effect of surgeon volume on mortality. J Vasc Surg 2008; 48:10. 

5. O'Donnell TFX, Li C, Swerdlow NJ, et al. The Weekend Effect in AAA Repair. Ann Surg 2019; 269:1170.

Wednesday, February 5, 2020

3 lung zones

Q: Tip of the pulmonary artery catheter (PAC) should be ideally positioned in zone 3, which is? (select one) 

A) above the level of the left atrium 
B) below the level of the left atrium 

 Answer: B

Lung is divided into 3 zones, known as West's Zones since described by Dr. West 55 years ago. This physiologic division is according to three different pressures in the lungs 

  •  mean arterial pressure(PA) 
  • mean alveolar pressure(Pa)
  • mean pulmonary capillary pressure(Pc) 

Zone 1 has PA>Pa>Pc

 Zone 2 has Pa>PA>Pc

 Zone 3 has Pa>Pc>PA

Tip of the PAC should be ideally positioned in zone 3 which is below the level of the left atrium and gives the appropriate Pulmonary Artery Occlusion Pressure (PAOP).



West J, Dollery C, Naimark A (1964). "Distribution of blood flow in isolated lung; relation to vascular and alveolar pressures". J Appl Physiol. 19: 713–24.

Tuesday, February 4, 2020

Angiotensin 2

Q: Angiotensin II works as a pressor via which electrolyte? 

Answer: calcium 

 Although clinical use of Angiotensin II infusion in ICUs is relatively recent but its mechanism of action is well known for decades. Angiotensin receptors (AT1 and AT2) are G-coupled protein receptors with angiotensin II as their ligand. Angiotensin II is a vasoconstrictor and is a part of the renin-aldosterone-angiotensin (RAAS) system. When receptors are stimulated, it leads to three effects to mediate vasoconstriction and better hemodynamic profile 

 1. cytosolic calcium concentration 

 2 aldosterone secretion 
 3. vasopressin secretion




Catt KJ, Mendelsohn FA, Millan MA, Aguilera G. The role of angiotensin II receptors in vascular regulation. J Cardiovasc Pharmacol 1984; 6 Suppl 4:S575.

Monday, February 3, 2020

Supplemental oxygen in cardioversion

Q: Supplemental oxygen should be turned off for a few seconds while electric cardioversion is performed? 

A) Yes 
B) No 

Answer:  A

Supplemental oxygen is a fire hazard! Turning off supplemental oxygen for a few seconds usually doesn't harm the patients as they already have enough reserve oxygen in dead space (denitrogenation). This mostly applies to patients with a nasal cannula, face mask, BiPAP, etc. Although the risk is very low in intubated patients where oxygen is supplied in a closed tubing, it is recommended to pause the ventilators for a few seconds. Risk is higher when oxygen concentration is equivalent or above 50% or is within 30 cm of applied pads.



1. ECRI Institute. Hazard report: using external defibrillators in oxygen-enriched atmospheres can cause fires. Health Devices 2005; 34: 423-425. 

2. American Heart Association Guidelines for CPR and ECC, 2005. Supplement to Circulation. 2005;112:IV-41.

Sunday, February 2, 2020

TRALI and Females

Q: To mitigate the side effect of Transfusion-related Acute Lung Injury (TRALI) deferral of female donors shown to have a favorable effect. Deferral of which female population has shown a better outcome? 

A) nulliparous 
B) multiparous

Answer: B

After a dramatic rise (awareness) of TRALI, "TRALI mitigation strategies" have been adopted by blood banks and has shown many favorable outcomes. One strategy is to defer the multiparous female donors for plasma transfusion. It was found that there is a dose-response increase in the frequency of anti-HLA antibodies according to parity, from 1.7 percent for never pregnant females to 32.2 percent for four or more pregnancies (reference#4).




1. Chapman CE, Stainsby D, Jones H, et al. Ten years of hemovigilance reports of transfusion-related acute lung injury in the United Kingdom and the impact of preferential use of male donor plasma. Transfusion 2009; 49:440.

2. Eder AF, Herron RM Jr, Strupp A, et al. Effective reduction of transfusion-related acute lung injury risk with male-predominant plasma strategy in the American Red Cross (2006-2008). Transfusion 2010; 50:1732. 
3. Lucas G, Win N, Calvert A, et al. Reducing the incidence of TRALI in the UK: the results of screening for donor leucocyte antibodies and the development of national guidelines. Vox Sang 2012; 103:10.

4. Triulzi DJ, Kleinman S, Kakaiya RM, et al. The effect of previous pregnancy and transfusion on HLA alloimmunization in blood donors: implications for a transfusion-related acute lung injury risk reduction strategy. Transfusion 2009; 49:1825.

Saturday, February 1, 2020


Q: Cytokine release syndrome (CRS) and Immune effector cell-associated neurotoxicity syndrome (ICANS)? 

 Answer: Cytokine release syndrome (CRS) is a supraphysiologic acute systemic inflammatory syndrome characterized by fever and multiple organ dysfunction that is associated with chimeric antigen receptor (CAR)-T cell therapy, therapeutic antibodies, and haploidentical allogeneic transplantation. Immune effector cell-associated neurotoxicity syndrome (ICANS) is a neuropsychiatric syndrome that can occur in some patients who are treated with immunotherapy and may or may not accompany CRS. 

 CRS severity is proportional with the disease burden.



1. Frey NV, Porter DL. Cytokine release syndrome with novel therapeutics for acute lymphoblastic leukemia. Hematology Am Soc Hematol Educ Program 2016; 2016:567.

2. Lee DW, Santomasso BD, Locke FL, et al. ASTCT Consensus Grading for Cytokine Release Syndrome and Neurologic Toxicity Associated with Immune Effector Cells. Biol Blood Marrow Transplant 2019; 25:625.