Wolff-Chaikoff effect

Q: What is Wolff-Chaikoff effect?

Answer: 

Normal human continues to have a wide variation in dietary iodine intake and is normally autoregulated (called organification) by thyroid follicular cells. When the thyroid gland suddenly gets exposed to excess of iodine, it stops the biosynthesis of thyroid hormones, irrespective of Thyroid Stimulating Hormone (TSH). This phenomenon is called the Wolff-Chaikoff effect. 

The above principle remains the mainstay of treatment in hyperthyroidism particularly in thyroid storm. Large infusion of iodine suppresses the thyroid gland. Similarly, patients who are on iodine-containing drugs such as amiodarone become hypothyroid under the same effect.

#endocrinology

References:

1.  Wolff J, Chaikoff IL (1948). "Plasma inorganic iodide as a homeostatic regulator of thyroid function". J Biol Chem. 174 (2): 555–564. doi:10.1016/S0021-9258(18)57335-X. PMID 18865621. Link: https://www.jbc.org/article/S0021-9258%2818%2957335-X/pdf

2. Markou K, Georgopoulos N, Kyriazopoulou V, Vagenakis AG. Iodine-Induced hypothyroidism. Thyroid. 2001 May;11(5):501-10. doi: 10.1089/105072501300176462. PMID: 11396709.

PD-5 I and LUTS

Q: Male patients using Phosphodiesterase 5 (PDE-5) inhibitors may experience increased urinary frequency and urgency.

A) True

B) False

Answer: B

In contrast to the statement in the above question, irrespective of improvement in erectile dysfunction, PDE-5 inhibitors have been found to improve lower urinary tract Symptoms (LUTS), particularly in male patients. 

#urology

#nephrology

References:

1. Liu L, Zheng S, Han P, Wei Q. Phosphodiesterase-5 inhibitors for lower urinary tract symptoms secondary to benign prostatic hyperplasia: a systematic review and meta-analysis. Urology 2011; 77:123.

2. Gacci M, Corona G, Salvi M, et al. A systematic review and meta-analysis on the use of phosphodiesterase 5 inhibitors alone or in combination with α-blockers for lower urinary tract symptoms due to benign prostatic hyperplasia. Eur Urol 2012; 61:994.

Ramelteon

Q: Melatonin is a chronobiotic?

A) True

B) false

Answer: A

Melatonin receptor agonists such as Ramelteon are increasingly used in ICUs. Ramelteon binds to the melatonin 1 and 2 receptors (MT1, MT2). It inhibits the wakefulness-promoting activity of the suprachiasmatic nucleus. It is most effective when patients have difficulty falling asleep. It reduces the time dedicated to light sleep but its efficacy on sleep continuity is not remarkable. Also, it has shown no improvement in daytime function.

Any hormone/chemical which helps to regulate circadian rhythm is called a chronobiotic.

#sleep

References:

1. Emens JS, Burgess HJ. Effect of Light and Melatonin and Other Melatonin Receptor Agonists on Human Circadian Physiology. Sleep Med Clin 2015; 10:435.

2. Dawson D, Armstrong SM. Chronobiotics--drugs that shift rhythms. Pharmacol Ther. 1996;69(1):15-36. doi: 10.1016/0163-7258(95)02020-9. PMID: 8857301.

Echo and IE

Q: For infective endocarditis (IE)Transthoracic echocardiography (TTE) has higher? (select one)

A) sensitivity

B) specificity

Answer: B

As per European Society of Cardiology (ESC) Guidelines, the estimated sensitivity of TTE for IE is around 70 percent for native valves and 50 percent for prosthetic valves. If noted, the specificity is around 90 percent. The visualization of vegetation can be compromised by thick chest wall (obesity), underlying valve thickening, valve calcification, redundant leaflet tissue, prosthetic shadowing, small vegetation or vegetation which has embolized. 

Interestingly, this is reverse for transesophageal echocardiography (TEE) due to better/clear visualization. TEE yields sensitivity of about 96 percent for native valves and 92 percent for prosthetic valves, and the specificity for both is about 90 percent.

#cardiology

#ID

#ECHO

References:

1. Habib G, Lancellotti P, Antunes MJ, et al. 2015 ESC Guidelines for the management of infective endocarditis: The Task Force for the Management of Infective Endocarditis of the European Society of Cardiology (ESC). Endorsed by: European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Nuclear Medicine (EANM). Eur Heart J 2015; 36:3075.

2. Bai AD, Steinberg M, Showler A, et al. Diagnostic Accuracy of Transthoracic Echocardiography for Infective Endocarditis Findings Using Transesophageal Echocardiography as the Reference Standard: A Meta-Analysis. J Am Soc Echocardiogr 2017; 30:639.

Tranexamic acid in hyperacute primary intraCerebral Hemorrhage.

Q: Tranexamic acid is another very useful drug to improve long-term functional outcomes if given early in hyperacute primary Intra Cerebral Hemorrhage (ICH).

A) True

B) False

Answer: B

Tranexamic acid works via inhibiting fibrinolysis and the proteolytic activity of plasmin. Unfortunately, it failed to show any utility in hyperacute primary ICH. It failed to show any difference in 90-day functional status or mortality. 

Said that it has shown some favor towards early reductions in hematoma growth and early death.

#neurology

#neuro-surgery

References:

1. Sprigg N, Flaherty K, Appleton JP, et al. Tranexamic acid for hyperacute primary IntraCerebral Haemorrhage (TICH-2): an international randomised, placebo-controlled, phase 3 superiority trial. Lancet 2018; 391:2107.

2. Meretoja A, Yassi N, Wu TY, et al. Tranexamic acid in patients with intracerebral haemorrhage (STOP-AUST): a multicentre, randomised, placebo-controlled, phase 2 trial. Lancet Neurol 2020; 19:980.

ACS and pulse-ox

Q: A good pulse-oximetry waveform indicates that the patient does not have acute compartment syndrome (ACS)?

A) Yes

B) No

Answer: B

Despite prolonged and severe ACS, arterial pulses and capillary refill can stay normal and should not be read as negative indicators of ACS. On the same note, open fractures should not be automatically assumed as contradicting ACS. 

Any suspicion of ACS should be properly evaluated clinically, radiologically, and ideally quantified by measurement.

#trauma

References:

1. Mars M, Hadley GP. Failure of pulse oximetry in the assessment of raised limb intracompartmental pressure. Injury 1994; 25:379.

2. DeLee JC, Stiehl JB. Open tibia fracture with compartment syndrome. Clin Orthop Relat Res 1981; :175.

3. Elliott KG, Johnstone AJ. Diagnosing acute compartment syndrome. J Bone Joint Surg Br 2003; 85:625.

daptomycin and myopathy

Q: When should daptomycin be considered discontinued in regards to myopathy?

Answer: The three major side effects which need to be watched during daptomycin therapy are

• myopathy
• peripheral neuropathy, and 
• eosinophilic pneumonia 

Regarding myopathy, treatment should be guided by the creatine phosphokinase (CPK) level.

- In symptomatic patients, daptomycin should be discontinued if CPK ≥5 times the upper limit of normal.

- In asymptomatic patients, daptomycin should be discontinued if CPK ≥10 times the upper limit of normal.

#ID

#pharmacology

References:

1. Skiest DJ. Treatment failure resulting from resistance of Staphylococcus aureus to daptomycin. J Clin Microbiol 2006; 44:655.

2. Veligandla SR, Louie KR, Malesker MA, Smith PW. Muscle pain associated with daptomycin. Ann Pharmacother. 2004 Nov;38(11):1860-2. doi: 10.1345/aph.1D639. Epub 2004 Sep 14. PMID: 15367725.

Cancer and COVID

Q: Cancer survivors who do not have active cancer have a higher risk for severe COVID-19? 

A) True

B) False

Answer: A

Although data is not very robust, it suggests that cancer survivors are prone to severe COVID-19 disease. The odd ratio can be up to 1.8. Unfortunately, patients with hematologic malignancy may have an even higher risk, up to fourfold. The risk decreases depending on the time difference between previous cancer and COVID infection.

#COVID-19

#oncology

References:

1. Williamson EJ, Walker AJ, Bhaskaran K, et al. Factors associated with COVID-19-related death using OpenSAFELY. Nature 2020; 584:430.

2. van Doesum J, Chinea A, Pagliaro M, et al. Clinical characteristics and outcome of SARS-CoV-2-infected patients with haematological diseases: a retrospective case study in four hospitals in Italy, Spain and the Netherlands. Leukemia 2020; 34:2536.

3. Mangone L, Gioia F, Mancuso P, et al. Cumulative COVID-19 incidence, mortality and prognosis in cancer survivors: A population-based study in Reggio Emilia, Northern Italy. Int J Cancer 2021.

tinnitus in acute salicylates toxicity

Q: 44 years old female is admitted to ICU with acute salicylates toxicity. The patient is complaining of severe tinnitus. Emergent Ear-Nose-Throat (ENT) consult is required.

A) True

B) False

Answer: B

Tinnitus is a very common finding in acute salicylate toxicity. It may even occur when salicylate is in the therapeutic range. The presence of tinnitus helps in confirming the diagnosis but it is almost always reversible and no further workup is usually needed. Patients may also complain of alterations in the perception of sound and/or transient hearing loss. Similarly, they are reversible and usually do not require any major intervention.

#toxicity

References:

1. Wecker H, Laubert A. Reversible Hörminderung bei akuter Salizylatintoxikation [Reversible hearing loss in acute salicylate intoxication]. HNO. 2004 Apr;52(4):347-51. German. doi: 10.1007/s00106-004-1065-5. PMID: 15143764.

2. Stolzberg D, Salvi RJ, Allman BL. Salicylate toxicity model of tinnitus. Front Syst Neurosci. 2012 Apr 20;6:28. doi: 10.3389/fnsys.2012.00028. PMID: 22557950; PMCID: PMC3341117.

Methamphetamine-induced toxicity: hyperthermia

Q: Acetaminophen is the first line of drugs in hyperthermia from acute methamphetamine intoxication.

A) True

B) False

Answer: B

Acetaminophen has no impact on acute intoxication from methamphetamine. This is because hyperthermia in this situation is due to high muscular activity and not a disturbance in hypothalamic temperature set point. Benzodiazepines and plus/minus neuromuscular blockade may be required. High muscular activity causes dehydration and requires aggressive fluid resuscitation.

Non-pharmacological interventions such as cooling blankets or evaporative cooling techniques are highly helpful. Lipid emulsion therapy is also suggested.

#toxicology

References:

1. Pillai S, Cesarz B, Boulware C, Khan A. Hypotension, Severe Hyperthermia (42°C), Rhabdomyolysis, and Disseminated Intravascular Coagulation Induced by Lethal Dose of Methamphetamine. Cureus. 2019;11(7):e5245. Published 2019 Jul 26. doi:10.7759/cureus.5245

2. Matsumoto RR, Seminerio MJ, Turner RC, et al. Methamphetamine-induced toxicity: an updated review on issues related to hyperthermia. Pharmacol Ther. 2014;144(1):28-40. doi:10.1016/j.pharmthera.2014.05.001

IABP effects

Q: Which of the following doesn't occur during Inflation and deflation of the intra-aortic balloon pump (IABP)?

A) Blood is displaced to the proximal aorta by inflation during diastole

B) Blood is displaced to the proximal aorta by deflation during diastole

C) Aortic volume is reduced during diastole

D) Vacuum effect is created by rapid balloon deflation during systole

Answer: B

IABP creates two major consequences for hemodynamics:

1. During diastole of the heartbeat cycle, the pump gets inflated and displaces the blood to the proximal aorta (choice A)

2. During the systole phase of the heartbeat cycle, aortic volume is decreased (choice C). This occurs due to an interesting phenomenon of a vacuum effect created by rapid balloon deflation (Choice D).

Choice B is wrong as IABP inflates during diastole (not deflate)

#hemodynamic

Reference:

Gajanan G, Brilakis ES, Siller-Matula JM, Zolty RL, Velagapudi P. The Intra-Aortic Balloon Pump. J Vis Exp. 2021 Feb 5;(168). doi: 10.3791/62132. PMID: 33616109.

DVT after ortho surgery

Q: The highest risk of Deep Vein Thrombosis (DVT) after orthopedic surgery is? (select one)

A) 1 - 6 days

B) 7- 14 days

C) 14 - 30 days

Answer: B

The high risk of DVT is well known after total hip arthroplasty (THA), total knee arthroplasty (TKA), and hip fracture surgery (HFS). This risk is highest between the first 7 to 14 days. 

Some of the less well-appreciated factors leading to DVT in postop period are injury to deep veins from the positioning of the extremity, compression of the femoral vein due to flexion, adduction of the hip during hip surgery, the anatomic position of the extremity, use of a thigh tourniquet during knee surgery, and bilateral arthroplasty.

#surgical-critical-care

#hematology

References:

1. Falck-Ytter Y, Francis CW, Johanson NA, et al. Prevention of VTE in orthopedic surgery patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012; 141:e278S.

2. White RH, Gettner S, Newman JM, et al. Predictors of rehospitalization for symptomatic venous thromboembolism after total hip arthroplasty. N Engl J Med 2000; 343:1758.

Renal US

 Q: Increased echogenicity and length <10 cm of kidney almost always indicates untreatable disease?

A) True

B) False

Answer: A

Ultrasound at the bedside is an increasingly common method to confirm diagnoses in ICU. So far kidneys have not been as popular as lungs, heart, and vessels to evaluate pathologies. The objective of this question is to bring to attention the fact that ultrasound is an effective tool for other organs in getting leads to diagnosis. 

Increased echogenicity let alone is a nonspecific finding but if it exists with kidney length <10 cm, it almost always indicates untreatable disease.

#ultrasound

#nephrology

Reference:

Moghazi S, Jones E, Schroepple J, et al. Correlation of renal histopathology with sonographic findings. Kidney Int 2005; 67:1515.

DD of purpura

Q: How the purpura of thrombocytopenia and purpura of vasculitis can be differentiated on physical exam?

Answer: Physical exam plays an integral role in differentiating purpura from thrombocytopenia and vasculitis.

Purpura secondary to thrombocytopenia 

• flat 
• non-blanching 
• in dependent areas

Purpura secondary to vasculitis 

• palpable 
• pruritic
• does not follow dependent areas

#hematology

#physical-exam

#rheumatology

References:

1. 1. KAWAKITA Y. [MEDICAL EXAMINATION AND TREATMENT OF PURPURA]. Nihon Ishikai Zasshi. 1964 Mar 1;51:781-809. Japanese. PMID: 14144733.

2. Stevens GL, Adelman HM, Wallach PM. Palpable purpura: an algorithmic approach. Am Fam Physician. 1995 Oct;52(5):1355-62. PMID: 7572558.

Albumin-Ca connection

Q: In hyperalbuminemia ____________ is expected? (select one)

A) hypocalcemia

B) hypercalcemia

Answer: B

In hyperalbuminemia total serum calcium level is expected to be high due to the calcium-albumin binding situation. This is not real hypercalcemia as ionized calcium stays normal. This is called pseudo or factitious hypercalcemia.

About half of the calcium in serum is bound to albumin. The best to have a calcium level is to measure ionized calcium. Unfortunately, it may not be readily available. Formulae have been developed to adjust calcium per albumin level. As a rule of thumb, for every 1 g/dL drop in the serum albumin the serum calcium drops by 0.8 mg/dL.

#electrolytes

References:

1. Thode J, Juul-Jørgensen B, Bhatia HM, Kjaerulf-Nielsen M, Bartels PD, Fogh-Andersen N, Siggaard-Andersen O. Comparison of serum total calcium, albumin-corrected total calcium, and ionized calcium in 1213 patients with suspected calcium disorders. Scand J Clin Lab Invest. 1989 May;49(3):217-23. Erratum in: Scand J Clin Lab Invest 1990 Feb;50(1):113. PMID: 2662382.

2. Lian IA, Åsberg A. Should total calcium be adjusted for albumin? A retrospective observational study of laboratory data from central Norway. BMJ Open. 2018;8(4):e017703. Published 2018 Apr 7. doi:10.1136/bmjopen-2017-017703

VRA and liver

Q: Which of the following vasopressin receptor antagonists should not be used in patients with liver cirrhosis?

A) tolvaptan

B) mozavaptan

C) satavaptan

D) lixivaptan

E) conivaptan

Answer: A

Vasopressin receptor antagonists act on three receptors i.e., V1a, V1b, and V2 receptors. 

• V1a and V1b receptors cause vasoconstriction and adrenocorticotropic hormone (ACTH) release
• V2 receptors mediates the antidiuretic response

All oral formulations i.e., tolvaptan, mozavaptan, satavaptan, and lixivaptan are V2 selective. Conivaptan is the only parenteral formulation, and acts on both V2 and V1a receptors. 

Tolvaptan is contraindicated in patients with liver issues.

#pharmacology

#nephrology

#endocrinology

#electrolytes

References:

1. Verbalis JG, Goldsmith SR, Greenberg A, et al. Hyponatremia treatment guidelines 2007: expert panel recommendations. Am J Med 2007; 120:S1.

2. Greenberg A, Verbalis JG. Vasopressin receptor antagonists. Kidney Int 2006; 69:2124.

3. Schrier RW, Gross P, Gheorghiade M, et al. Tolvaptan, a selective oral vasopressin V2-receptor antagonist, for hyponatremia. N Engl J Med 2006; 355:2099.

acetazolamide in severe exacerbation of COPD requiring invasive vent

Q: Acetazolamide is an effective way to counteract metabolic alkalosis in patients with acute exacerbation of COPD who requires intubation?

A) True

B) False

Answer: B

Despite theoretical benefit, acetazolamide failed to show any major impact in acute exacerbation of COPD. In ICUs, these patients frequently go into metabolic alkalosis due to nasogastric (NG) suctioning, diuretic and steroid use. Metabolic alkalosis may lead to suppression of central respiratory drive. Unfortunately, acetazolamide is not of much help in reducing days on ventilators.

#ventilators

#pulmonary

References:

1. Faisy C, Meziani F, Planquette B, et al. Effect of Acetazolamide vs Placebo on Duration of Invasive Mechanical Ventilation Among Patients With Chronic Obstructive Pulmonary Disease: A Randomized Clinical Trial. JAMA 2016; 315:480.

2. Bahloul M, Chaari A, Tounsi A, et al. Impact of acetazolamide use in severe exacerbation of chronic obstructive pulmonary disease requiring invasive mechanical ventilation. Int J Crit Illn Inj Sci 2015; 5:3.

postprandial angina

Q: Postprandial angina is usually associated with severe coronary vessel disease? 

A) True

B) False

Answer: A

Postprandial chest pain is in general of gastrointestinal origin. If associated with coronary origin, it can be an alarming situation. It signifies possible left main or multi-vessel coronary disease. For reason not entirely clear, it usually occurs after dinner. 

Also, it may occur postprandially at rest making diagnosis even harder.

#cardiology

References:

1. Chung WY, Sohn DW, Kim YJ, et al. Absence of postprandial surge in coronary blood flow distal to significant stenosis: a possible mechanism of postprandial angina. J Am Coll Cardiol 2002; 40:1976.

2. Berlinerblau R, Shani J. Postprandial angina pectoris: clinical and angiographic correlations. J Am Coll Cardiol. 1994 Mar 1;23(3):627-9. doi: 10.1016/0735-1097(94)90746-3. PMID: 8113544.

ibutilide

Q: Which one intervention may decrease the risk of torsades de pointes with ibutilide? 

Answer: Pretreatment with intravenous (IV) magnesium 

Ibutilide is not very popular for use as chemical agent for cardioversion in acute atrial fibrillation. This is due to it's risk to cause torsades de pointes. A less known fact is that it is more effective to convert atrial flutter to sinus rhythm. Pretreatment with IV magnesium decreases the risk of ibutilide-induced torsades de pointes. Risk factors for ibutilide-induced torsades de pointes are heart failure, baseline prolong QTc interval, hypokalemia or hypomagnesemia. 

The dose of Ibutilide in average adult patient is 1 mg over 10 minutes. If no or partial response, a second bolus of 1 mg over 10 minutes can be used. 

#cardiology

References:

1. Stambler BS, Wood MA, Ellenbogen KA, et al. Efficacy and safety of repeated intravenous doses of ibutilide for rapid conversion of atrial flutter or fibrillation. Ibutilide Repeat Dose Study Investigators. Circulation 1996; 94:1613.

2. Abi-Mansour P, Carberry PA, McCowan RJ, et al. Conversion efficacy and safety of repeated doses of ibutilide in patients with atrial flutter and atrial fibrillation. Study Investigators. Am Heart J 1998; 136:632.

3. Vinson DR, Lugovskaya N, Warton EM, Rome AM, Stevenson MD, Reed ME, Nagam MR, Ballard DW; Pharm CAFÉ Investigators of the CREST Network. Ibutilide Effectiveness and Safety in the Cardioversion of Atrial Fibrillation and Flutter in the Community Emergency Department. Ann Emerg Med. 2018 Jan;71(1):96-108.e2. doi: 10.1016/j.annemergmed.2017.07.481. Epub 2017 Sep 29. PMID: 28969929.

magnesium and morphine

Q: Intravenous Magnesium (IV Mg) potentiates the opioid effect? 

A) True

B) False

Answer: A

IV Mg is considered a usual adjuvant with opioids. It potentiates the opioid effect and so reduces it's dose requirement. This is due to its antagonist property of N-methyl-D-aspartate(NMDA) receptor. If utilized in perioperative time, it reduces opioid consumption as well as pain scores in first 24 hours postop period. IV Mg can be given as bolus and/or continuous infusion.

#pharmacology

#pain

#surgical-critical-care

References:

1. Albrecht E, Kirkham KR, Liu SS, Brull R. Peri-operative intravenous administration of magnesium sulphate and postoperative pain: a meta-analysis. Anaesthesia 2013; 68:79.

2. De Oliveira GS Jr, Castro-Alves LJ, Khan JH, McCarthy RJ. Perioperative systemic magnesium to minimize postoperative pain: a meta-analysis of randomized controlled trials. Anesthesiology 2013; 119:178.

BP from legs

Q; Lower extremity blood pressure measurement is usually _________ than upper extremity blood pressure? 

A) higher

B) lower

Answer: A

It is a common scenario in ICU when nursing staff has to rely on blood pressure (BP) measurement from lower extremities, particularly in patients with vascular fistulae or grafts. By default, the systolic pressure (SBP) in legs is usually higher than that in the arms (brachial artery). The difference on an average is by about 10 mmHg in the calf. It is even higher in the ankle by 17 mmHg. 

This does not apply to people with peripheral vascular disease (PVD) who usually have SBP lower at the ankle than the arm. Also, it is important that proper cuff size is applied.

#hemodynamics

References:

1. Measurement of Blood Pressure: Taking Blood Pressure in the Thigh. In: Kaplan's Clinical Hypertension, Kaplan NM, Victor RG (Eds).

2. Sheppard JP, Albasri A, Franssen M, et al. Defining the relationship between arm and leg blood pressure readings: a systematic review and meta-analysis. J Hypertens 2019; 37:660.

3. Allison MA, Hiatt WR, Hirsch AT, et al. A high ankle-brachial index is associated with increased cardiovascular disease morbidity and lower quality of life. J Am Coll Cardiol 2008; 51:1292.

cholesterol emboli

Q: Skin findings in cholesterol crystal emboli are more pronounced at? (select one)

A) arterial area

B) venous area

Answer: A

The classic cutaneous manifestations of cholesterol emboli are livedo reticularis, gangrene, cyanosis, ulcer, purpura, petechiae, splinter, and/or firm, painful erythematous nodules.

Contrary to popular belief, these signs tend to occur around/at palpable arterial pulse. The most common etiology for cholesterol emboli is manipulation of an artery like angiography, and embolization occurring in smaller arteries down the system.

#PVD

#cardiovascular

#procedures

References:

1. Donohue KG, Saap L, Falanga V. Cholesterol crystal embolization: an atherosclerotic disease with frequent and varied cutaneous manifestations. J Eur Acad Dermatol Venereol 2003; 17:504.

2. Fine MJ, Kapoor W, Falanga V. Cholesterol crystal embolization: a review of 221 cases in the English literature. Angiology 1987; 38:769.

3. Falanga V, Fine MJ, Kapoor WN. The cutaneous manifestations of cholesterol crystal embolization. Arch Dermatol 1986; 122:1194.

Delirium per DSM-5

Q) Hypo or hyperactivity is required to have a diagnosis of delirium?

A) True

B) False

Answer: B

Conventionally, delirium has been divided into hypo, hyper, or mixed activity types but is not required as a diagnosis per the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5). The five key features described are:

1. Disturbance in attention (reduced ability to direct, focus, sustain, and shift attention) and awareness.

2. The disturbance develops over a short period of time (usually hours to days), represents a change from baseline, and tends to fluctuate during the course of the day.

3. An additional disturbance in cognition (memory deficit, disorientation, language, visuospatial ability, or perception).

4. The disturbances are not better explained by another preexisting, evolving, or established neurocognitive disorder, and do not occur in the context of a severely reduced level of arousal, such as coma.

5. There is evidence from the history, physical examination, or laboratory findings that the disturbance is caused by a medical condition, substance intoxication or withdrawal, or medication side effect.

#psychiatry

Reference:

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 5th ed, APA Press, Washington, DC 2013.

Acetaminophen toxicity with tobacco

Q: Acetaminophen toxicity corelates in direct proportion with tobacco consumption (means higher the cigarettes per day higher the chances of toxicity)?

A) True

B) false

Answer: B

Although tobacco is an independent risk factor for acetaminophen toxicity, it has no direct correlation with the amount of tobacco or number of cigarettes per day. Even a small amount of tobacco consumption can increase acetaminophen toxicity. This is due to the fact that tobacco smoke contains CYP1A2 inducers which increases oxidative metabolism. 

A large number of smokers are simultaneously regular users of alcohol which further increases the risk of mortality.

#toxicology

References:

1. Dong SX, Ping ZZ, Xiao WZ, et al. Effect of active and passive cigarette smoking on CYP1A2-mediated phenacetin disposition in Chinese subjects. Ther Drug Monit 1998; 20:371.

2. Seo KW, Park M, Kim JG, et al. Effects of benzothiazole on the xenobiotic metabolizing enzymes and metabolism of acetaminophen. J Appl Toxicol 2000; 20:427.

3. Schmidt LE, Dalhoff K. The impact of current tobacco use on the outcome of paracetamol poisoning. Aliment Pharmacol Ther 2003; 18:979.

Post thoracentesis CXR

Q: A follow-up CXR despite an uncomplicated ultrasound (US) guided thoracentesis in an unventilated patient should be performed as occult pneumothorax (PTX) may occur? 

A) True

B) False

Answer: B

In an uncomplicated US-guided thoracentesis, chances of PTX are extremely low, particularly in an unventilated patient. Said that it should be performed if a patient displays any symptoms or if the air is noted in a syringe while performing thoracentesis. It is a good practice to quickly scan a patient's chest with an ultrasound probe after the procedure to establish the sliding of pleurae. Also, documenting post-procedure US images in the medical chart is desirable.

#procedure

References:

1. Thomsen TW, DeLaPena J, Setnik GS. Videos in clinical medicine. Thoracentesis. N Engl J Med 2006; 355:e16.

2. Petersen WG, Zimmerman R. Limited utility of chest radiograph after thoracentesis. Chest 2000; 117:1038.

Wheeze and stridor

Q: Stridor is usually predominantly? (select one)

A) expiratory

B) inspiratory

Answer: B

The objective of this question is to appreciate the difference between wheezing and stridor on physical exam. There are two major differences:

• Wheezing usually occurs in expiration. In contrast, stridor is predominantly inspiratory.
• Wheezing sounds like a continuous musical sound with single or multiple notes. Stridor is mostly monophonic.

Also, stridor is best heard over the anterior neck.

#physical-exam

#pulmonary

References:

1. Bohadana A, Izbicki G, Kraman SS. Fundamentals of lung auscultation. N Engl J Med 2014; 370:744.

2. Loudon R, Murphy RL Jr. Lung sounds. Am Rev Respir Dis 1984; 130:663.

3. Forgacs P. The functional basis of pulmonary sounds. Chest 1978; 73:399.