apical-radial pulse deficit in atrial fibrillation

Q: What is the reason behind an apical-radial pulse deficit in atrial fibrillation (AF)?

Answer: Palpating the apical and radial pulse rates simultaneously commonly gives a lower radial heart rate. This is called apical-radial pulse deficit, and the most probable cause is AF. In AF, some ventricular beats are preceded by shorter diastole periods with reduced left ventricular filling and suboptimum stroke volume. This results in an unpalpable pressure wave down the arm. This also results in wide measurements of Cuff BP. 

Such wide variation in cuff BP measurement should prompt a physician to look for an underlying Subclinical AF (SCAF).

#cardiology

References: 

1. Karadavut S, Altintop I. Pulse deficit in atrial fibrillation - a different perspective on rhythm or rate control strategy. Kardiol Pol. 2021;79(11):1231-1238. doi: 10.33963/KP.a2021.0107. Epub 2021 Sep 10. PMID: 34506629.

2. Mawatari K, Sanada J, Kuroiwa N, Okumiya K, Nakamura K, Hashimoto S. [Mechanism of production of pulse deficit in atrial fibrillation: assessment by blood flow dynamics]. J Cardiol. 1988 Mar;18(1):197-205. Japanese. PMID: 3221309.

Naegleria fowleri

Case: 24 years old male is admitted 5 days after his visit to a water park with seizure, fever, severe headache, and altered mental status. There is a strong suspicion of Naegleria fowleri due to similar cases reported previously in the city. A spinal tap has been performed. Cerebrospinal fluid (CSF) pressure is expected to be? (select one) 

A) high

B) low

Answer: A

Naegleria fowleri is an ameboflagellate protozoan parasite and is distributed worldwide. Due to its thermophilic character, it is found in warm water sources. Recreational water activities are a well-known source of infection. It may cause primary amebic meningoencephalitis (PAM), an acute hemorrhagic meningoencephalitis.

CSF tends to be yellowish-white to grayish color before turning into a frankly hemorrhagic fluid. Characteristically, CSF pressure is very high, ranging from 300 to 600 mm H20, strongly favoring Naegleria fowleri. Diagnosis should be made in conjunction with epidemiological, clinical, radiological, and laboratory findings.

#ID

#neurology

References:

1. Visvesvara GS, Moura H, Schuster FL. Pathogenic and opportunistic free-living amoebae: Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri, and Sappinia diploidea. FEMS Immunol Med Microbiol 2007; 50:1.

2. Visvesvara GS. Free-living amebae as opportunist agents of human disease. J Neuroparasitol 2010; 1:1.

3. Qvarnstrom Y, Visvesvara GS, Sriram R, da Silva AJ. Multiplex real-time PCR assay for simultaneous detection of Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri. J Clin Microbiol 2006; 44:3589.

sodium in MELD score

Q: Why sodium has been made part of MELD-Na score?

Answer: In January 2016 MELD (Model For End-Stage Liver Disease) score was updated to include serum sodium after evidences showed that severity of the hyponatremia corelates with the severity of cirrhosis and vasodilatory state. There is a linear increase in mortality by 5 percent for each mmol decrease in serum sodium between 125 and 140 mmol/L. 

Said that clinicians should be reminded that serum sodium can be manipulated by volume status and  diuretic use.

#hepatology

References:

1. Kim WR, Biggins SW, Kremers WK, et al. Hyponatremia and mortality among patients on the liver-transplant waiting list. N Engl J Med 2008; 359:1018.

2. Londoño MC, Cárdenas A, Guevara M, et al. MELD score and serum sodium in the prediction of survival of patients with cirrhosis awaiting liver transplantation. Gut 2007; 56:1283.

3. Ruf AE, Kremers WK, Chavez LL, et al. Addition of serum sodium into the MELD score predicts waiting list mortality better than MELD alone. Liver Transpl 2005; 11:336.

Polypill

 

Reference: 

 Jose M. Castellano et. al Polypill Strategy in Secondary Cardiovascular Prevention. DOI: 10.1056/NEJMoa2208275

Negative symptoms

Q: What does "negative symptoms" means in psychosis stands for?

Answer: Negative symptoms refer to decreased emotional expression, lack of normal behavior, and lack of motivation. Clinically they signify hard to treat psychosis. Also, it points toward the likelihood of schizophrenia. It usually consists of five constructs: 

• blunted affect
• alogia (reduction in quantity of words spoken)
• avolition (reduced goal-directed activity due to decreased motivation)
• asociality (lacking social interaction)
• anhedonia (reduced experience of pleasure) 

#psychiatry

References:

1. Correll CU, Schooler NR. Negative Symptoms in Schizophrenia: A Review and Clinical Guide for Recognition, Assessment, and Treatment. Neuropsychiatr Dis Treat. 2020 Feb 21;16:519-534. doi: 10.2147/NDT.S225643. PMID: 32110026; PMCID: PMC7041437.

2. Fusar-Poli P, Papanastasiou E, Stahl D, et al. Treatments of Negative Symptoms in Schizophrenia: Meta-Analysis of 168 Randomized Placebo-Controlled Trials. Schizophr Bull 2015; 41:892.

3. Németh G, Laszlovszky I, Czobor P, et al. Cariprazine versus risperidone monotherapy for treatment of predominant negative symptoms in patients with schizophrenia: a randomised, double-blind, controlled trial. Lancet 2017; 389:1103.

Bolus magnesium in preeclampsia

Case: 28 years old female with renal insufficiency is admitted to ICU with severe preeclampsia. Patient can receive the usual loading dose of Magnesium?

A) True

B) False

Answer: A

Although magnesium is renally excreted, the bolus dose can stay the same in preeclampsic patients with kidney disorder. This is since the volume of its distribution is not altered. After the bolus dose, the maintenance dose should be reduced and adjusted per level. The levels should be checked every one to two hours. Also, clinical signs should be regularly monitored to check for the continuous presence of patellar reflex.

#ob-gyn

Reference:

Gestational Hypertension and Preeclampsia: ACOG Practice Bulletin, Number 222. Obstet Gynecol 2020; 135:e237.

Perforation in sigmoid volvulus

Q: Patient with perforation in sigmoid volvulus requires immediate? (select one)

A) resection

B) volvulus detorsed

Answer: B

The objective of this question is to highlight an important concept during the management of bowel ischemia, i.e., impending risk of reperfusion ischemia. 

Patients who develop perforation or peritonitis due to volvulus prefer to have a resection of the compromised bowel in its volvulized position. A surgeon may even decide to perform a segmental resection or even a subtotal colectomy. Hartmann's procedure is very frequently performed, i.e., no reconstruction instead of colorectal anastomosis +/- diversion due to commonly associated clinical signs in this situation such as hemodynamic instability, coagulopathy, and acidosis. Detorsion of the bowel can set up reperfusion injury.

#surgical-critical-care

Reference:

Vogel JD, Feingold DL, Stewart DB, et al. Clinical Practice Guidelines for Colon Volvulus and Acute Colonic Pseudo-Obstruction. Dis Colon Rectum 2016; 59:589.

Wellens pattern

Q: What is "Wellens pattern" on EKG?

Answer: The "Wellens pattern" is also known as LAD-T-wave inversion pattern. As the name implies, it is marked by deep T-wave inversions in multiple precordial leads, mostly V1 to V4. Despite signs of severe ischemia, there may not be any cardiac enzyme elevations or any ST elevations. 

This signifies high-grade stenosis in the Left Anterior Descending (LAD) coronary artery. It can be life-threatening.

#cardiology

References:

1. Rhinehardt J, Brady WJ, Perron AD, Mattu A. Electrocardiographic manifestations of Wellens' syndrome. Am J Emerg Med 2002; 20:638.

2. Haines DE, Raabe DS, Gundel WD, Wackers FJ. Anatomic and prognostic significance of new T-wave inversion in unstable angina. Am J Cardiol 1983; 52:14.

3. de Zwaan C, Bär FW, Janssen JH, et al. Angiographic and clinical characteristics of patients with unstable angina showing an ECG pattern indicating critical narrowing of the proximal LAD coronary artery. Am Heart J 1989; 117:657.

eyes in SJS and TEN

Q: Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) usually do not have ocular involvement?

A) True

B) False

Answer: B

Most of the patients with SJS and TEN has ocular involvement mostly as conjunctivitis, corneal ulcer, anterior uveitis, panophthalmitis, pain, photophobia and purulent discharge. In severe cases bullae may form. Ocular severity in SJS/TEN is grade as

0 - no involvement

1 - conjunctival hyperemia

2 - ocular surface epithelial defect or pseudomembrane formation

3 - both ocular surface epithelial defect and pseudomembrane formation 

Although signs and symptoms are reversible but may take longer time to resolve.

#opthalmology

#dermatology

References:

1. Sekula P, Dunant A, Mockenhaupt M, et al. Comprehensive survival analysis of a cohort of patients with Stevens-Johnson syndrome and toxic epidermal necrolysis. J Invest Dermatol 2013; 133:1197.

2. Hsu DY, Brieva J, Silverberg NB, et al. Pediatric Stevens-Johnson syndrome and toxic epidermal necrolysis in the United States. J Am Acad Dermatol 2017; 76:811.

3. Mittmann N, Knowles SR, Koo M, et al. Incidence of toxic epidermal necrolysis and Stevens-Johnson Syndrome in an HIV cohort: an observational, retrospective case series study. Am J Clin Dermatol 2012; 13:49.

Volume vs water balance

Q: Serum sodium concentration represents? (select one)

A) volume balance

B) water balance

Answer: B

This question's objective is to highlight that water balance and volume balance are two different entities. Serum sodium level provides information only on total body water balance. Other clinical and laboratory factors should be considered to determine total body volume balance. Merely looking at serum sodium concentration does not determine 'dry' vs. 'wet' status. Water deficit is a complex phenomenon and rarely occurs acutely in the human body unless there is a reason to believe in any accelerated water losses.

#electrolytes

Reference:

Sterns RH, Silver SM. Salt and water: read the package insert. QJM 2003; 96:549.

"Rebound" COVID-19 after nirmatrelvir-ritonavir treatment

"Rebound" COVID-19 after nirmatrelvir-ritonavir treatment 

A course of Nirmatrelvir-Ritonavir (Paxlovid) has become a standard of care in the United States for COVID-19 patients, particularly those who stay outside the hospital and have moderate or are at high risk of severe symptoms. Initial data shows that it decreases hospitalization. 

In some patients, "rebound" COVID-19 has been reported with positive rapid antigen testing. Symptoms may recur too. The median time of recurrence of symptoms is 9 days. Re-treatment is not needed, but isolation is required.

#COVID-19

#ID

References:

1. Ranganath N, O'Horo JC, Challener DW, et al. Rebound Phenomenon after Nirmatrelvir/Ritonavir Treatment of Coronavirus Disease-2019 in High-Risk Persons. Clin Infect Dis 2022.

2. US Food and Drug Administration. FDA updates on Paxlovid for health care providers. Available at: https://www.fda.gov/drugs/news-events-human-drugs/fda-updates-paxlovid-health-care-providers (Accessed on August 20, 2022).

3. Centers for Disease Control and Prevention. COVID-19 rebound after Paxlovid treatment. Available at: https://emergency.cdc.gov/han/2022/han00467.asp (Accessed on August 20, 2022).

Phenytoin-diazepam interaction

Case: 24 years old male is admitted to ICU with seizures requiring benzodiazepine drip. Phenytoin is ordered. Which one precaution should be directed to the nursing staff?

Answer: Phenytoin and benzodiazepine should not be given via the same IV line

Phenytoin is incompatible with any of the benzodiazepines. Precipitation is likely to occur if infusion occurs through the same intravenous line. This same principle applies to phenytoin with any other fluid or medication containing glucose or dextrose. 

Fosphenytoin does not have this interaction.

#neurology

#pharmacology

Reference:

Murphy A, Wilbur K. Phenytoin-diazepam interaction. Ann Pharmacother. 2003 May;37(5):659-63. doi: 10.1345/aph.1C413. PMID: 12708941.

EKG in hyperkalemia

Q: Which of the following is the earlier sign of hyperkalemia? (select one)

A) disappearance of P wave 

B) tall peaked T waves

Answer: B

The effect of potassium on EKG is progressive and can help a clinician to take preemptive actions. EKG usually changes in hyperkalemia in the following order.

• Tall peaked T waves with a shortened QT interval (earliest sign)
• progressive lengthening of the PR interval and QRS duration
• disappearance of P wave
• widening of QRS complex
• sine wave
• ventricular standstill (asystole)

Said that clinician needs to be aware of the pitfall that the progression and severity of EKG changes do not correlate, and other factors highly effect the EKG changes (very common in ICU and renal patients) like hypocalcemia, acid/base imbalance, and hyponatremia.

#cardiology

References:

1. Montague BT, Ouellette JR, Buller GK. Retrospective review of the frequency of ECG changes in hyperkalemia. Clin J Am Soc Nephrol 2008; 3:324.

2. Aslam S, Friedman EA, Ifudu O. Electrocardiography is unreliable in detecting potentially lethal hyperkalaemia in haemodialysis patients. Nephrol Dial Transplant 2002; 17:1639.

3. Montague BT, Ouellette JR, Buller GK. Retrospective review of the frequency of ECG changes in hyperkalemia. Clin J Am Soc Nephrol. 2008 Mar;3(2):324-30. doi: 10.2215/CJN.04611007. Epub 2008 Jan 30. PMID: 18235147; PMCID: PMC2390954.

Asymptomatic TAA repair indications

Q: One of the indications of Thoracic Aortic Aneurysm (TAA) is? (select one)

A) End-diastolic aortic diameter >5.5 cm

B) End-systolic aortic diameter >5.5 cm

Answer: A

All symptomatic TAA should be repaired but major indications for the repair of TAA are

• End-diastolic aortic diameter >5.5 cm
• Aortic size index i.e., aortic diameter divided by body surface area ≥2.75 cm/m2
• Aortic area over height ratio i.e., maximal aortic cross-sectional area divided by height >10 cm2/m 

#surgical-critical-care

#cardiology

References:

1. Hiratzka LF, Bakris GL, Beckman JA, et al. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with Thoracic Aortic Disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine. Circulation 2010; 121:e266.

2. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM GUIDELINES FOR THE DIAGNOSIS AND MANAGEMENT OF PATIENTS WITH THORACIC AORTIC DISEASE REPRESENTATIVE MEMBERS*, Hiratzka LF, Creager MA, et al. Surgery for Aortic Dilatation in Patients With Bicuspid Aortic Valves: A Statement of Clarification From the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation 2016; 133:680.

3. Knipp BS, Deeb GM, Prager RL, et al. A contemporary analysis of outcomes for operative repair of type A aortic dissection in the United States. Surgery 2007; 142:524.

4.Erbel R, Aboyans V, Boileau C, et al. 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases: Document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC). Eur Heart J 2014; 35:2873.

5. Davies RR, Gallo A, Coady MA, et al. Novel measurement of relative aortic size predicts rupture of thoracic aortic aneurysms. Ann Thorac Surg 2006; 81:169.

KS and smoking

Q: Smoking may _______________ the risk of Kaposi Sarcoma (KS)? (select one)

A) increases

B) decreases

Answer: B

Interestingly, tobacco abusers are found to have a reduced risk of KS, particularly in the classic type. The probable mechanism is the direct effect of nicotine on immune function and its tendency to cause vasoconstriction. This led to using of nicotine dermal patches over KS, although there is no strong evidence to support its widespread use. Said that it does not cause any major systemic effect and may be of use in clinical practice. 

Other useful topical agents are Cis-retinoic acid, Imiquimod, Timolol, topical silver nitrate, and Rapamycin.

#oncology

Reference:

Goedert JJ, Scoppio BM, Pfeiffer R, Neve L, Federici AB, Long LR, Dolan BM, Brambati M, Bellinvia M, Lauria C, Preiss L, Boneschi V, Whitby D, Brambilla L. Treatment of classic Kaposi sarcoma with a nicotine dermal patch: a phase II clinical trial. J Eur Acad Dermatol Venereol. 2008 Sep;22(9):1101-9. doi: 10.1111/j.1468-3083.2008.02720.x. Epub 2008 Apr 1. PMID: 18384551.

Potassium adaptation

Q: What is Potassium adaptation?

Answer: Higher intake of potassium is rarely a cause of hyperkalemia in a normal individual. This is due to the efficient cellular and urinary response. This phenomenon is called potassium adaptation.

Clinical significance:  Persistent hyperkalemia in a patient should prompt a clinician to look for a pathology either cellular or renal.

#electrolytes

#nephrology

References:

1. Youn JH, McDonough AA. Recent advances in understanding integrative control of potassium homeostasis. Annu Rev Physiol 2009; 71:381.

2. Mount DB, Zandi-Nejad K. Disorders of potassium balance. In: Brenner and Rector's The Kidney, 9th Ed, WB Saunders & Company, Philadelphia 2011. p.640.

3. Hayslett JP, Binder HJ. Mechanism of potassium adaptation. Am J Physiol. 1982 Aug;243(2):F103-12. doi: 10.1152/ajprenal.1982.243.2.F103. PMID: 7051849.

Dig and heart blocks

Q: Which of the following second-degree heart block is more common with digoxin toxicity? (select one)

A) Mobitz type I (Wenckebach) 

B) Mobitz type II 

Answer: A

Most of the patients on dig therapy have some degree of first-degree AV block with PR lengthening. One of the earliest signs of excessive serum digoxin is a more marked widening of the PR interval to above 0.2 sec. Second-degree block of the Mobitz type I (Wenckebach) is a sign of dig toxicity in these patients. Mobitz type II block rarely occurs only due to dig. toxicity.

#cardiology

References:

1. Djohan AH, Sia CH, Singh D, Lin W, Kong WK, Poh KK. A myriad of electrocardiographic findings associated with digoxin use. Singapore Med J. 2020 Jan;61(1):9-14. doi: 10.11622/smedj.2020005. PMID: 32043160; PMCID: PMC7900815.

2. Hornestam B, Held P, Edvardsson N. Effects of digoxin on electrocardiogram in patients with acute atrial fibrillation--a randomized, placebo-controlled study. Digitalis in Acute Atrial Fibrillation (DAAF) Trial Group. Clin Cardiol. 1999 Feb;22(2):96-102. doi: 10.1002/clc.4960220208. PMID: 10068846; PMCID: PMC6656138.

CD associated cardic disease

Q: One of the clinical symptoms of cardiomyopathy associated with Chagas Disease (CD) is? (select one)

A) bradycardia out of proportion to fever

B) tachycardia out of proportion to fever 

Answer: B

Initial signs and symptoms of CD are usually benign. Interestingly, symptomatic myocarditis is typically mild if it occurs via the vector-borne route but severe if it occurs via the oral route. The clinical signs of cardiac involvement in an acute CD are dyspnea, fatigue, chest pain, arrhythmias, and sudden cardiac arrest.

Tachycardia out of proportion to fever is a non-specific sign but favors the diagnosis of CD.

#cardiology

#ID

References:

1. Nunes MCP, Beaton A, Acquatella H, et al. Chagas Cardiomyopathy: An Update of Current Clinical Knowledge and Management: A Scientific Statement From the American Heart Association. Circulation 2018; 138:e169.

2. Parada H, Carrasco HA, Añez N, et al. Cardiac involvement is a constant finding in acute Chagas' disease: a clinical, parasitological and histopathological study. Int J Cardiol 1997; 60:49.

3.Bastos CJ, Aras R, Mota G, et al. Clinical outcomes of thirteen patients with acute chagas disease acquired through oral transmission from two urban outbreaks in northeastern Brazil. PLoS Negl Trop Dis 2010; 4:e711.

"downhill" esophageal varices in hemodialysis patients

Q: What is "downhill" esophageal varices?

Answer: Patients on permanent hemodialysis (HD) and upper-extremity access often develop superior vena cava (SVC) obstruction. This SVC obstruction leads to varices in the upper esophagus. It is called "downhill" esophageal varices because the direction of the blood flow is downwards. These varices can be reversed with SVC obstruction relief. Management in case of acute bleeding requires endoscopic band ligation or sclerotherapy.

#GI

#vascular

References:

1. Blam ME, Kobrin S, Siegelman ES, Scotiniotis IA. "Downhill" esophageal varices as an iatrogenic complication of upper extremity hemodialysis access. Am J Gastroenterol 2002; 97:216.

2. Chandra A, Tso R, Cynamon J, Miller G. Massive upper GI bleeding in a long-term hemodialysis patient. Chest 2005; 128:1868.

3. Loudin M, Anderson S, Schlansky B. Bleeding 'downhill' esophageal varices associated with benign superior vena cava obstruction: case report and literature review. BMC Gastroenterol 2016; 16:134.

Topical BB

Case: 62 years old female recently diagnosed with open-angle glaucoma, otherwise healthy, is admitted to ICU with severe airway obstruction requiring a non-invasive ventilation mask. Which drug is probably the culprit?

Answer: Topical Beta-blocker (BB)

This question aims to establish that topical BB can lead to severe airway obstruction, even in patients with no established history of airway disease. Topical BB should be considered a systemic treatment and prescribed cautiously in patients with underlying lung and heart disease. 

#pulmonary

#opthalmology

References:

1. Kirwan JF, Nightingale JA, Bunce C, Wormald R. Beta blockers for glaucoma and excess risk of airways obstruction: population based cohort study. BMJ 2002; 325:1396.

2. Kirwan JF, Nightingale JA, Bunce C, Wormald R. Do selective topical beta antagonists for glaucoma have respiratory side effects? Br J Ophthalmol 2004; 88:196.

Performance status scales

Q: The Palliative Performance Scale (PPS) of zero is equivalent to? (select one)

A) Full functional status

B) Death

Answer: B

Studies have shown that patient's performance status is highly related to his survival time in terminal cancer. Three scales are widely used to predict survival depending on performance status.

• Eastern Cooperative Oncology Group (ECOG) performance status 
• Karnofsky Performance Status (KPS) 
• Palliative Performance Scale (PPS)

KPS is measured on a scale of 0-100 points, while PPS is measured on a scale of  0-100%. On both scales, zero means death. ECOG has a scale of 0-4 where 4 means completely disabled.

All three scores are freely available from any search engine.

#end-of-life

#palliativecare

#oncology

References:

1. Oken MM, Creech RH, Tormey DC, et al. Toxicity and response criteria of the Eastern Cooperative Oncology Group. Am J Clin Oncol 1982; 5:649.

2. Downing M, Lau F, Lesperance M, et al. Meta-analysis of survival prediction with Palliative Performance Scale. J Palliat Care 2007; 23:245.

3. de Kock I, Mirhosseini M, Lau F, et al. Conversion of Karnofsky Performance Status (KPS) and Eastern Cooperative Oncology Group Performance Status (ECOG) to Palliative Performance Scale (PPS), and the interchangeability of PPS and KPS in prognostic tools. J Palliat Care 2013; 29:163.

Mannitol induced AKI

Q: Mannitol induced Acute Kidney Injury (AKI) can be made rapidly reversible by hemodialysis (HD)?

A) True

B) False

Answer: A

Patients who receive excessive amount of mannitol may develop AKI particularly if plasma osmolal gap goes above 60 to 75 mosmol/kg or if when plasma mannitol concentration goes beyond 1100 mg/dL. This is also known as mannitol nephrotoxicity syndrome. Mannitol induced AKI is usually and by default reversible. Risk factors include CHF, diabetes, preexisting renal disease, concomitant use of nephrotoxic drugs and other diuretics. 

The time period of AKI can be shortened by HD. The half life of mannitol is around 36 hours, HD shorten it to only 6 hours. It may require only one or two sessions of HD.

#nephrology

#pharmacology

Reference:

Gadallah MF, Lynn M, Work J. Case report: mannitol nephrotoxicity syndrome: role of hemodialysis and postulate of mechanisms. Am J Med Sci 1995; 309:219.

RVF in PE

Q: What is the mechanism of Right Ventricular Failure (RVF) in Pulmonary Embolism (PE)?

Answer: The objective of this question is to underline the fact that understanding the pathophysiology of any systemic disease goes a long way in clinicians' management of disease down the line. 

RVF occurs in PE via stepwise systemic failure. It largely depends on the clot burden and the physical obstruction of the vascular bed. This leads to hypoxia and subsequently vasoconstriction within the pulmonary arterial system, called hypoxic response. Increased vasoconstriction increases pulmonary vascular resistance (PVR). Increased PVR impedes right ventricular outflow., which progressively leads to right ventricular dilation, and flattening or bowing of the intraventricular septum. RV dilatation and decreased flow from RV eventually lead to cardiogenic collapse.

In conclusion, pulmonary hypoxic vasoconstriction plays an integral role in RV failure due to PE.

#cardiology

#pulmonary

References:

1. Bryce YC, Perez-Johnston R, Bryce EB, Homayoon B, Santos-Martin EG. Pathophysiology of right ventricular failure in acute pulmonary embolism and chronic thromboembolic pulmonary hypertension: a pictorial essay for the interventional radiologist. Insights Imaging. 2019 Feb 13;10(1):18. doi: 10.1186/s13244-019-0695-9. PMID: 30758687; PMCID: PMC6375098.

2. Arrigo M, Huber LC, Winnik S, Mikulicic F, Guidetti F, Frank M, Flammer AJ, Ruschitzka F. Right Ventricular Failure: Pathophysiology, Diagnosis and Treatment. Card Fail Rev. 2019 Nov 4;5(3):140-146. doi: 10.15420/cfr.2019.15.2. PMID: 31768270; PMCID: PMC6848943.

Cyanide toxicity

Case: 42 years old male is brought to ED with suspected cyanide poisoning after ingesting a large amount of apricot. While putting Central Venous Catheter (CVC), blood is expected to be? (select one)

A) dark purple

B) bright red

Answer: B

This question's objective is to look for clues in cyanide poisoning. Pertinent history plays an important role. On physical exam, patient may appear flushed with "cherry red" color. Labs may show a high anion gap and elevated lactic acid. Arterial and venous blood gas (ABG and VBG) may have a narrowed venous-arterial PO2 gradient, and venous blood may appear bright red. Hydroxocobalamin is the preferred antidote.

#toxicity

References:

1. Hall AH, Rumack BH. Clinical toxicology of cyanide. Ann Emerg Med 1986; 15:1067.

2. Gracia R, Shepherd G. Cyanide poisoning and its treatment. Pharmacotherapy. 2004 Oct;24(10):1358-65. doi: 10.1592/phco.24.14.1358.43149. PMID: 15628833.

Sodium and potassium channel blockade

Q: Blockade of sodium channel leads to prolongation of QT interval on EKG?

A) True

B) False

Answer: B

The rule of thumb is

• Sodium channel blockade causes prolongation of the QRS interval
• Potassium channel blockade causes prolongation of the QT interval

Cocaine is a classic example of sodium channel blockade. and antipsychotics are classic examples of potassium channel blockade.

#cardiology

References:

1. Roden DM, George AL Jr. Structure and function of cardiac sodium and potassium channels. Am J Physiol. 1997 Aug;273(2 Pt 2):H511-25. doi: 10.1152/ajpheart.1997.273.2.H511. PMID: 9277464.

2. Balser JR. The cardiac sodium channel: gating function and molecular pharmacology. J Mol Cell Cardiol. 2001 Apr;33(4):599-613. doi: 10.1006/jmcc.2000.1346. PMID: 11273715.

3. Starmer CF, Reddy MR, Namasivayam A, Singh M. Potassium channel blockade amplifies cardiac instability numerical studies of torsades de pointes. Indian J Physiol Pharmacol. 1994 Oct;38(4):259-66. PMID: 7883289.

Riedel's lobe

Q: What is Riedel's lobe of liver?

Answer: Riedel's lobe is an anatomic variation. It can easily deceive a clinician as hepatomegaly as it extends below the level of the umbilicus. It is a right-sided tail or tongue-like downward projection from the right lobe of the liver. It is a benign condition but should be watched for as 30 percent of the population may carry it. 

Further reading with pictures can be obtained from the given reference below.

#hepatology

Reference:

Savopoulos C, Kakaletsis N, Kaiafa G, Iliadis F, Kalogera-Fountzila A, Hatzitolios AI. Riedel's lobe of the liver: a case report. Medicine (Baltimore). 2015 Jan;94(3):e430. doi: 10.1097/MD.0000000000000430. PMID: 25621695; PMCID: PMC4602636.

ACE-I and ARBs in CKDs

Q: The use of angiotensin converting enzyme (ACE) inhibitor is absolutely contraindicated in patients with serum creatinine concentrations more than 3 mg/dL? 

A) True 

B) False 

 

Answer: B 

The objective of this question is to highlight the fact that angiotensin converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) are relatively contraindicated even in patients with serum creatinine concentrations above 3 mg/dL. This is due to their beneficial effect on patients with impaired left ventricular function. It has a survival benefit with lower mortality. This benefit is seen in all kidney function strata. 

#cardiology 

#pharmacology 

#nephrology 

 

References: 

 1. Frances CD, Noguchi H, Massie BM, et al. Are we inhibited? Renal insufficiency should not preclude the use of ACE inhibitors for patients with myocardial infarction and depressed left ventricular function. Arch Intern Med 2000; 160:2645. 

 2. Evans M, Carrero JJ, Szummer K, et al. Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers in Myocardial Infarction Patients With Renal Dysfunction. J Am Coll Cardiol 2016; 67:1687.

clubbing in IPF

Q: Clubbing in Interstitial Lung disease (ILD) is __________  manifestation? (select one)

A) early

B) late

Answer: B

Clinical history and physical exam plays an integral role in differential diagnosis of ILD, like clubbing is common in idiopathic pulmonary fibrosis (IPF) and asbestosis) but rare in sarcoidosis and hypersensitivity pneumonitis. If present in ILD, it suggests advanced pulmonary fibrosis.

Clubbing is also a feature of cystic fibrosis, pulmonary arteriovenous malformations, cyanotic heart disease, malignancies of the lung and pleura, and inflammatory bowel disease.

#physical-exam

#pulmonary

Reference:

van Manen MJG, Vermeer LC, Moor CC, Vrijenhoeff R, Grutters JC, Veltkamp M, Wijsenbeek MS. Clubbing in patients with fibrotic interstitial lung diseases. Respir Med. 2017 Nov;132:226-231. doi: 10.1016/j.rmed.2017.10.021. Epub 2017 Nov 2. PMID: 29229102.

LTACs

Q: Patients transferred from ICU to long-term acute care (LTAC) facilities may require to keep a length of stay (LOS) for at least how many days?

Answer: ≥25 days

ICU physicians on daily basis need to make decisions about the appropriateness of patient transfer to different facilities besides regular wards or step-down units. A large portion of these patients go to LTAC facilities, particularly those patients who are still dependent on ventilators or had multi-system organ failure (MSOF). Three major criteria usually required are

• must maintain an average length of stay ≥25 days
• must require daily monitoring 
• must require complex medical interventions

#discharge-planning

Reference:

Kahn JM, Benson NM, Appleby D, et al. Long-term acute care hospital utilization after critical illness. JAMA 2010; 303:2253.

primary hyperthyroidism

Q: All of the following favor the diagnosis of primary hyperparathyroidism EXCEPT?

A) asymptomatic patient 

B) chronic hypercalcemia

C) postmenopausal status (females)

D) evidence of sarcoidosis

E) evidence of multiple endocrine neoplasia (MEN)

Answer: D

The objective of this question is to highlight the importance of skill of history taking. In hyperparathyroidism, etiology and level of hypercalcemia play an integral part in determining the urgency, further diagnostic workup and management. For example, hypercalcemia due to cancer is usually very high, symptomatic, urgent, and responsive. 

Evidence of sarcoidosis (choice D) makes it secondary hyperparathyroidism. Following are the usual features of primary hyperparathyroidism:

• an asymptomatic patient 
• mild or borderline chronic hypercalcemia
• a postmenopausal female
• usually a normal physical examination
• no cause of hypercalcemia 
• family history of hyperparathyroidism
• evidence of multiple endocrine neoplasia

#endocrinology

References:

1. Walker MD, Silverberg SJ. Primary hyperparathyroidism. Nat Rev Endocrinol. 2018 Feb;14(2):115-125. doi: 10.1038/nrendo.2017.104. Epub 2017 Sep 8. PMID: 28885621; PMCID: PMC6037987. 

2. Sun B, Guo B, Wu B, Kang J, Deng X, Zhang Z, Fan Y. Characteristics, management, and outcome of primary hyperparathyroidism at a single clinical center from 2005 to 2016. Osteoporos Int. 2018 Mar;29(3):635-642. doi: 10.1007/s00198-017-4322-7. Epub 2017 Dec 3. PMID: 29198075.