octreotide in chylothorax

Q: How octreotide helps in chylothorax? 

Answer:

Octreotide can be an important adjunct therapy in chylothorax. It works via two mechanisms 

•  decrease the volume of fluid within the thoracic duct by inhibiting gastric, pancreatic, and biliary secretions, and 
•  inhibiting absorption of chyle from the intestine

One dose regimen is 50 to 100 mcg SQ 3/day.


#pharmacology


References:

1. Kalomenidis I. Octreotide and chylothorax. Curr Opin Pulm Med 2006; 12:264.

2.  Al-Zubairy SA, Al-Jazairi AS. Octreotide as a therapeutic option for management of chylothorax. Ann Pharmacother 2003; 37:679. 

3. Evans J, Clark MF, Mincher L, Varney VA. Chylous effusions complicating lymphoma: a serious event with octreotide as a treatment option. Hematol Oncol 2003; 21:77.

murmur in venous air embolism

Q: Which murmur is heard in venous air embolism?

Answer: Millwheel murmur 

 A millwheel murmur is a churning sound that can be heard throughout the cardiac cycle. In such cases, other clinical signs are usually evident. This murmur is usually present with a patient gasping or coughing,, tachypnea, tachycardia or bradycardia, hemodynamic instability, crackles, elevated jugular venous pressure (JVP), and hypoxemia.

#pulmonology
#physical-exam


Reference:

1. Gordy S, Rowell S. Vascular air embolism. Int J Crit Illn Inj Sci. 2013;3(1):73–76. doi:10.4103/2229-5151.109428

Clonidine toxicity

Q: Which of the following is recommended for clonidine toxicity?

A) Naloxone 
B) Tolazoline
C) Yohimbine
D) Hemodialysis
E) Beta-blocker


Answer: A

Naloxone is the only drug that has shown some benefit in clonidine toxicity particularly with central effect i.e, marked drowsiness or coma. Even data on Naloxone is limited. Clonidine toxicity is mostly managed as supportive treatment. In the past, alpha-adrenergic antagonists, tolazoline, and yohimbine have been suggested as antidotes but their side-effect profile is riskier than benefit of its use. Clonidine is not removed by hemodialysis. Clonidine itself can cause marked bradycardia and the use of beta-blocker would be potentially more harmful.

#pharmacology
#toxicology


References:

1. Seger DL, Loden JK. Naloxone reversal of clonidine toxicity: dose, dose, dose. Clin Toxicol (Phila) 2018; 56:873. 

2. Shannon M, Neuman MI. Yohimbine. Pediatr Emerg Care 2000; 16:49.

3. Gummin DD, Mowry JB, Spyker DA, et al. 2016 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 34th Annual Report. Clin Toxicol (Phila) 2017; 55:1072.

BB and Dobutamine

Q: Which Beta-blocker is particularly more potent in blocking the effectiveness of Dobutamine?



Answer:  Carvedilol

In patients who are on chronic beta-blocker therapy, dobutamine is usually not a preferred inotrope. Dobutamine is primarily a beta-agonist. There is weak literature to suggest that out of all beta-blockers, carvedilol is more prone to block dobutamine effectiveness. This is more crucial to know as carvedilol is the preferred beta-blockers for congestive heart failure (CHF) patients in outpatient. When these patients get admitted to ICU with CHF exacerbation, both can't be used simultaneously. In such cases, PDE-3 inhibitor is preferred if no other contra-indication, such as hypotension or vasoplegia.

Said that, data in this area of CHF management i.e., concomitant use of dobutamine and various BBs is still not very evidence-based, and usually gets guided by bedside clinician's experience and judgment.

#cardiology
#pharmacology


References:

1. Metra M, Nodari S, D'Aloia A, et al. Beta-blocker therapy influences the hemodynamic response to inotropic agents in patients with heart failure: a randomized comparison of dobutamine and enoximone before and after chronic treatment with metoprolol or carvedilol. J Am Coll Cardiol 2002; 40:1248. 

2. Luiz Carlos Santana Passos; Andréa Cristina Costa Barbosa; Márcio Galvão Oliveira; Edval Gomes Santos Jr. Is there evidence favoring the use of beta-blockers and dobutamine in acute heart failure? Arquivos Brasileiros de Cardiologia Arq. Bras. Cardiol. vol.100 no.2 São Paulo Feb. 2013 http://dx.doi.org/10.5935/abc.20130034

LGIB - high risk features

Q: A non-tender abdomen is considered a high risk feature in presumed acute lower gastro-intestinal (GI) bleeding.

A) True
B) False


Answer: A

Some risk factors in presumed acute lower GI bleeding are expected but few are quiet unusual like a non-tender abdomen and no diarrhea.  Other known risk factors in acute lower GI bleed are significant hypotension, other comorbidities, old age, diverticulosis, angiodysplasia, aspirin use, coagulopathy, hypoalbuminemia, elevated blood urea nitrogen (BUN) level and leucocytosis.

#gastroenterology


References:

1. Kollef MH, O'Brien JD, Zuckerman GR, Shannon W. BLEED: a classification tool to predict outcomes in patients with acute upper and lower gastrointestinal hemorrhage. Crit Care Med 1997; 25:1125. 

2. Velayos FS, Williamson A, Sousa KH, et al. Early predictors of severe lower gastrointestinal bleeding and adverse outcomes: a prospective study. Clin Gastroenterol Hepatol 2004; 2:485. 

3. Strate LL, Orav EJ, Syngal S. Early predictors of severity in acute lower intestinal tract bleeding. Arch Intern Med 2003; 163:838. 

4. Das A, Ben-Menachem T, Cooper GS, et al. Prediction of outcome in acute lower-gastrointestinal haemorrhage based on an artificial neural network: internal and external validation of a predictive model. Lancet 2003; 362:1261. 

5. Aoki T, Nagata N, Shimbo T, et al. Development and Validation of a Risk Scoring System for Severe Acute Lower Gastrointestinal Bleeding. Clin Gastroenterol Hepatol 2016; 14:1562.

earplugs in ICU

Q: Use of earplugs may decrease the incidence of delirium in ICU patients?

A) True
B) False


Answer: A

At least one randomized trial has shown that using earplugs at night is associated with a lower incidence of delirium in ICU. This is probably due to decrease noise pollution and improved physiologic sleep. This effect can further be enhanced by supplementing other endeavors like avoiding elective nursing interventions at night hours, and prescribing medications during awake hours.

#delirium


References:

Van Rompaey B, Elseviers MM, Van Drom W, et al. The effect of earplugs during the night on the onset of delirium and sleep perception: a randomized controlled trial in intensive care patients. Crit Care 2012; 16:R73.

plasma osmolality during ICH

Q: What is the goal of plasma osmolality with mannitol therapy during the management of intracranial hemorrhage (ICH)? 


Answer: 300 to 310 mosmol/kg

Mannitol continues to be the mainstay of treatment in acute management of ICH to quickly and effectively lowers Intracranial Pressure (ICP). But few basic tenets should be kept in mind. Firstly, the goal of mannitol therapy in ICH is to achieve plasma hyperosmolality to 300-310 mosmol/kg. This allows water to exit the brain. During this quest, the plasma osmolal gap should not be allowed to exceed 55 mosmol/kg. Moreover, the upper limit of total mannitol dose is 250 mg/kg every 4 hours. These boundaries have been set to avoid acute kidney injury which can be deadly due to loss of major volume regulator.

#neurology
#neurosurgery
#surgical-criticalcare


References:

1. Helbok R, Kurtz P, Schmidt JM, et al. Effect of mannitol on brain metabolism and tissue oxygenation in severe haemorrhagic stroke. J Neurol Neurosurg Psychiatry 2011; 82:378. 

2. Ropper AH. Management of raised intracranial pressure and hyperosmolar therapy. Pract Neurol 2014; 14:152. 

3. Dorman HR, Sondheimer JH, Cadnapaphornchai P. Mannitol-induced acute renal failure. Medicine (Baltimore) 1990; 69:153.

dialysis dementia

Q; Which element is considered to be responsible for dementia in dialysis patient, commonly known as dialysis dementia? 

 
Answer:  Aluminum

Dialysis dementia is usually slow progressing but in some cases may occur as acute encephalopathy, marked by mental status change, hallucinations, seizures, and coma. In many countries the major reason for such incidents are water supply which is heavily contaminated with aluminum. This issue can be solved by improved water purification.

#nephrology


References:

1. Berend K, van der Voet G, Boer WH. Acute aluminum encephalopathy in a dialysis center caused by a cement mortar water distribution pipe. Kidney Int 2001; 59:746.

2. National Kidney Foundation. K/DOQI clinical practice guidelines for bone metabolism and disease in chronic kidney disease. Am J Kidney Dis 2003; 42:S1.

3. Pierides AM, Edwards WG Jr, Cullum UX Jr, et al. Hemodialysis encephalopathy with osteomalacic fractures and muscle weakness. Kidney Int 1980; 18:115.

SDD

Q: What is the rationale behind "Short daily dialysis (SDD)?

Answer: Studies have shown benefits from SDD both in terms of dialysis efficiency and hemodynamic stability. 

During SDD, shortening the dialysis time while increasing the frequency of dialysis allows more time to be spent dialyzing against higher uremic solute concentration gradients. This enhances the efficiency of solute removal. Ultimately, a new steady-state with lower peak but higher trough solute concentrations are achieved. Also, more frequent dialysis allows for less body fluid accumulation and increased potential for normalizing the extracellular fluid volume. 

 Frequent Hemodialysis Network (FHN) daily trial was a multicenter, randomized trial. It showed that both primary composite outcomes showed benefit with SDD i.e., 

•  death or one-year change from baseline in left ventricular (LV) mass, and 
•  death or one-year change in physical health

This rationale is very much applicable to patients with longer length of stay (LOS).

#nephrology

References:

Henderson LW, Leypoldt JK, Lysaght MJ, Cheung AK. Death on dialysis and the time/flux trade-off. Blood Purif 1997; 15:1.

FHN Trial Group, Chertow GM, Levin NW, et al. In-center hemodialysis six times per week versus three times per week. N Engl J Med 2010; 363:2287.

Fenoldopam

Q:  Which one advantage Fenoldopam has over other parenteral anti-hypertensives? 

Answer: Although Fenoldopam is not much-used in ICUs, it is the only parenteral antihypertensive infusion agent, which maintains or increases renal perfusion while it lowers the blood pressure. Fenoldopam is a peripheral dopamine-1 receptor agonist.

#cardiology
#nephrology
#pharmacology


Reference:

Murphy MB, Murray C, Shorten GD. Fenoldopam: a selective peripheral dopamine-receptor agonist for the treatment of severe hypertension. N Engl J Med 2001; 345:1548.

Aspiration Pneumonia and unusual interventions

Q: Mention two unconventional interventions that have shown benefit in acute aspiration pneumonia?

Answer: Mechanical ventilation is the most conventional modality to sustain lung function during acute aspiration pneumonia. The oxygenation and protection of airway are directly supplemented by positive pressure effects on lung parenchyma. Some clinicians apply a short course of steroids to mitigate the effects of chemical burn/inflammation. Two other very unusual interventions in this scenario which are not well known but have shown benefits are 

• Intravenous high molecular weight colloids, and 
• Sodium nitroprusside infusion into the pulmonary artery

By increasing colloid pressure in alveolar vessels and the supply of blood via vasodilation, the effects of direct effects from acute aspiration on alveoli can be minimized. The data is almost 4 decades old and requires reproducibility. At this juncture,  it may only be of academic interest for clinicians.

#pulmonary

References:

1. Broe PJ, Toung TJ, Permutt S, Cameron JL. Aspiration pneumonia: treatment with pulmonary vasodilators. Surgery 1983; 94:95. 

2. Peitzman AB, Shires GT 3rd, Illner H, Shires GT. Pulmonary acid injury: effects of positive end-expiratory pressure and crystalloid vs colloid fluid resuscitation. Arch Surg 1982; 117:662. 

3. Toung TJ, Cameron JL, Kimura T, Permutt S. Aspiration pneumonia: treatment with osmotically active agents. Surgery 1981; 89:588.

SK and allergic reaction

Q: 44-year-old male developed an allergic reaction during Streptokinase (SK) infusion for massive pulmonary embolism with fever, shivering, and generalized rash. In this patient, the clinical efficacy of SK and thrombolytic therapy is reduced?

A) Yes
B) No

Answer: No

Few major takeaway points to remember if SK has been chosen for thrombolytic therapy

• Major allergic reaction due to SK infusion particularly the first time is a rare event, although mild pyrexia and shivering may occur.
• Mere hypotension during SK infusion without any other sign of allergic reaction is not considered a reaction. It may be just a histaminoid event and can be handled with slowing of the infusion, intravenous fluids (IVF) bolus, or transient pressor support. 
• The efficacy of SK as a thrombolytic therapy is not decreased if an allergic reaction occurs.  
• If an allergic reaction occurs after SK infusion, patient stays at risk for an allergic reaction for about 7-8 years

#pulmonary
#pharmacology
#immunology


References:

1. Tsang TS, Califf RM, Stebbins AL, et al. Incidence and impact on outcome of streptokinase allergy in the GUSTO-I trial. Global Utilization of Streptokinase and t-PA in Occluded Coronary Arteries. Am J Cardiol 1997; 79:1232. 

2. Squire IB, Lawley W, Fletcher S, et al. Humoral and cellular immune responses up to 7.5 years after administration of streptokinase for acute myocardial infarction. Eur Heart J 1999; 20:1245.

postprandial syndrome

Q: Postprandial hypoglycemia syndrome requires the nadir of blood glucose to at least which concentration? 

 Answer: None 

 Postprandial hypoglycemia syndrome is not diagnosed by low glucose blood level as studies have shown that there is no correlation between blood glucose concentrations and the occurrence of symptoms during a four-to-six-hour after an oral glucose tolerance test (OGTT). Postprandial hypoglycemia syndrome is a misnomer as this is not a true hypoglycemic disorder. Experts have settled this issue decades ago. This should be referred to as an only postprandial syndrome. It is defined by a time period: symptoms like hypoglycemia i.e. anxiety, weakness, tremor, perspiration, or palpitations occurring within four hours after meals. 

It is a more complex phenomenon, not a diagnosis itself rather symptomatic presentation of an underlying disorder. This syndrome is mostly associated with Post Roux-en-Y gastric bypass, Factitious hypoglycemia from insulin or sulfonylurea, Gin and tonic hypoglycemia, Hereditary fructose intolerance, Insulin autoimmune hypoglycemia, Insulinoma, Noninsulinoma pancreatogenous hypoglycemia syndrome, and Pancreatic transplantation.

#endocrinology
 
References:

1. Johnson DD, Dorr KE, Swenson WM, Service FJ. Reactive hypoglycemia. JAMA 1980; 243:1151. 

2. MCDONALD GW, FISHER GF, BURNHAM C. REPRODUCIBILITY OF THE ORAL GLUCOSE TOLERANCE TEST. Diabetes 1965; 14:473. 

3. Charles MA, Hofeldt F, Shackelford A, et al. Comparison of oral glucose tolerance tests and mixed meals in patients with apparent idiopathic postabsorptive hypoglycemia: absence of hypoglycemia after meals. Diabetes 1981; 30:465.

IE and procedure indicated

Q: For patients who develop infective endocarditis (IE) due to group D streptococci and E. faecalis, which non-cardiac procedure should be performed? 



Answer: colonoscopy

Patients who get identified as IE due to group D streptococci ((Streptococcus bovis/Streptococcus equinus complex) and E. faecalis, a colonoscopy should be performed. Colon cancer is found to be highly associated with these patients. 

It is not fully clear why these bugs are highly associated with colon cancer but at least in case of group D streptococci, it is suggested that proteins presented in S. bovis biotype I bind to overexpressed ligands in colonic neoplasms. Simultaneously, S. bovis biotype I can form biofilms on collagen-rich surfaces of valve endothelium. 

#cardiology
#infectious-diseases
#gastroenterology
#oncology


References: 

1. Boleij A, Muytjens CM, Bukhari SI, et al. Novel clues on the specific association of Streptococcus gallolyticus subsp gallolyticus with colorectal cancer. J Infect Dis 2011; 203:1101. 

2. Pericàs JM, Corredoira J, Moreno A, et al. Relationship Between Enterococcus faecalis Infective Endocarditis and Colorectal Neoplasm: Preliminary Results From a Cohort of 154 Patients. Rev Esp Cardiol (Engl Ed) 2017; 70:451. 

3. Escolà-Vergé L, Peghin M, Givone F, et al. Prevalence of colorectal disease in Enterococcus faecalis infective endocarditis: results of an observational multicenter study. Rev Esp Cardiol (Engl Ed) 2019.

pupillary responses of hepatic encephalopathy

Q: How the pupillary response differs at different grades of hepatic encephalopathy?

Answer: Cerebral edema correlates with the degree of liver failure causing increased intracranial pressure. Pupillary examination is a good surrogate to determine the level of hepatic encephalopathy besides other clinical signs.

• Grade I - normal response
• Grade II - hyperresponsive
• Grade III - slowly responsive
• Grade IV - fixed and dilated

#physical-exam
#neurology
#hepatology


References:

1. Gill RQ, Sterling RK. Acute liver failure. J Clin Gastroenterol 2001; 33:191.

2. Shawcross DL, Wendon JA. The neurological manifestations of acute liver failure. Neurochem Int. 2012 Jun;60(7):662-71. doi: 10.1016/j.neuint.2011.10.006. Epub 2011 Nov 2.

Angled chest tube

Q: 'Angled' chest tubes are best suited to reach which pleural area?

Answer: Posterior costophrenic sulcus

Posterior costophrenic sulcus is the recess area between the ribs and the lateral-most portion of the diaphragm, partially occupied by the most caudal part of the lung

Despite placement of straight chest tubes of bigger diameter, fluid from the posterior costophrenic sulcus can not be drained properly. Angled chest tubes are appropriate to properly drained this obscure area. 

#procedure


Reference:

Yu H. Management of pleural effusion, empyema, and lung abscess. Semin Intervent Radiol. 2011;28(1):75–86. doi:10.1055/s-0031-1273942

chronic DIC

Q: All of the following can be a finding in chronic Disseminated Intravascular Coagulation (DIC) except?

A) Mild thrombocytopenia
B) Mildly prolonged PT
C) Mildly prolonged aPTT
D) Decreased plasma fibrinogen
E) Elevated plasma D-dimer


Answer: D

The teaching point for this pearl is to emphasize that in chronic DIC, fibrinogen level is unreliable.

Classic findings of DIC can be seen only in acute DIC with thrombocytopenia, prolonged PT and aPTT, low plasma fibrinogen and elevated plasma D-dimer. In chronic DIC there may be mild or no thrombocytopenia, normal or mildly prolonged PT and aPTT and elevated plasma D-dimer, but in contrast to acute DIC, plasma fibrinogen may be normal or even slightly elevated.

#hematology


Reference:

1. Wada H, Matsumoto T, Yamashita Y. Diagnosis and treatment of disseminated intravascular coagulation (DIC) according to four DIC guidelines. J Intensive Care. 2014;2(1):15. Published 2014 Feb 20. doi:10.1186/2052-0492-2-15

2. Venugopal A. Disseminated intravascular coagulation. Indian J Anaesth. 2014;58(5):603–608. doi:10.4103/0019-5049.144666

Platelets storage

Q: In contrast to other blood products why platelets are stored at room temperature?

Answer: 

Platelets are recommended to be stored at room temperature with a shelf half-life of 5-7 days. Cold causes clustering of von Willebrand factor receptors on the platelet surface. This leads to expediting the clearance of platelets by liver macrophages. 

Cryopreserved platelets can be preserved for years but are not approved for the general public in USA but have been utilized in war zones.

#hematology


References:

1. Murphy S, Gardner FH. Effect of storage temperature on maintenance of platelet viability--deleterious effect of refrigerated storage. N Engl J Med 1969; 280:1094. 

2. Hoffmeister KM, Felbinger TW, Falet H, et al. The clearance mechanism of chilled blood platelets. Cell 2003; 112:87. Marks DC. Cryopreserved platelets: are we there yet? Transfusion 2018; 58:2092.

Heparin, bleeding and PTT

Q: "Bleeding due to heparin is usually directly proportional to the level of aPTT." This statement is

A) True
B) False



Answer: B

Contrary to popular belief bleeding from heparin administration/infusion has a very poor correlation with aPTT level. In fact, the major risk factors are

•  recent surgery
• trauma
• underlying malignancy
• hepatic disease
• other bleeding disorder
• old age
• female gender, and
• underlying anemia

#hematology

Reference:

1. Juergens CP, Semsarian C, Keech AC, et al. Hemorrhagic complications of intravenous heparin use. Am J Cardiol 1997; 80:150.

2. Hull RD, Raskob GE, Rosenbloom D, et al. Heparin for 5 days as compared with 10 days in the initial treatment of proximal venous thrombosis. N Engl J Med 1990; 322:1260.

Tacrolimus and hypertension

Q: After organ transplantation, the patients who are on Calcium Channel Blockers (CCBs), the dose of tacrolimus should be? (select one)

A) Increased
B) Decreased


Answer: B

CCBs are one of the drugs of choice if antihypertensive treatment is needed in patients on cyclosporine or tacrolimus. This is due to the fact that one reason for development of hypertension in patients on this immuno-suppressant is renal vasoconstriction. CCBs particularly diltiazem is known to reverse this process and may have a protective effect. Said that diltiazem impairs metabolism of these drugs, so the dose of this immuno-suppressant should be decreased and managed closely by trough levels.

#pharmacology
#transplantation 


References:


Kuypers DR, Neumayer HH, Fritsche L, et al. Calcium channel blockade and preservation of renal graft function in cyclosporine-treated recipients: a prospective randomized placebo-controlled 2-year study. Transplantation 2004; 78:1204.

VA ECMO and cardiac thrombosis

Q: What's the etiology behind cardiac thrombosis in extracorporeal membrane oxygenation (ECMO) inserted through femoral vessels?


Answer: 

Most of the Veno-Arterial (VA) ECMO are inserted in ICU are through femoral artery and vein in emergent code situations. This creates a retrograde blood flow in the ascending aorta resulting in stasis of the blood in left ventricle. Unfortunately, most of these patients have a poor left ventricular function which exacerbates the risk of cardiac thrombosis. Proper anti-coagulation is a prerequisite to avoid this complication.

#procedures
#cardiology
#surgical-critical-care


Reference:

Makdisi G, Hashmi ZA, Wozniak TC, Wang IW. Left ventricular thrombus associated with arteriovenous extra corporeal membrane oxygenation. J Thorac Dis. 2015;7(11):E552–E554. doi:10.3978/j.issn.2072-1439.2015.11.18

prolonged postop ileus

Q: In general, how many days after surgery, if no bowel motility returns are considered as 'prolonged postoperative ileus'?


Answer: 4

'Postoperative ileus' is confounded by so many factors in an individualized patient that it is hard to put this period in black and white. Per an international consensus panel fewer than four days after surgery for bowel movement, passing of flatus or stool or tolerance of diet is considered "normal" or "obligatory" postoperative ileus. The panel also defined "prolonged" postoperative ileus as the occurrence of two or more of the following by postoperative day 4 or after:

• Nausea or vomiting
• Inability to tolerate an oral diet over the preceding 24 hours 
• Absence of flatus over the last 24 hours 
• Abdominal distention 
• Radiologic confirmation of ileus  

#surgical-critical-care


Reference:

Vather R, Trivedi S, Bissett I. Defining postoperative ileus: results of a systematic review and global survey. J Gastrointest Surg 2013; 17:962.

Electrical burn injury

Q: Why deep tissue surrounding the long bones are prone to highest damage during electrical burn injury?

Answer: Bones have the highest resistance of any body tissue to electricity, and so reflexly generates the highest amount of heat when exposed to an electrical current. Therefore, the deep tissue surrounding the long bones gets enormous damage during electrical burn injury including periosteal burns and destruction of bone matrix.

#trauma


Reference:

Jain S, Bandi V. Electrical and lightning injuries. Crit Care Clin 1999; 15:319.

ACS

Q: Which is the one required component to diagnose acute chest syndrome (ACS) in patients with sickle cell disease?



Answer: Radiographic evidence of a new segmental (at least one complete segment) pulmonary infiltrate.

Above is the required component to diagnose ACS when it is present with any of the following

• Temperature ≥38.5°C
• >2 percent decrease O2 saturation from a documented steady-state value on room air
• PaO2 less than 60 mmHg 
• Tachypnea  
• Intercostal retractions
• Nasal flaring
• Use of accessory muscles of respiration
• Chest pain 
• Cough 
• Wheezing 
• Rales

#Pulmonary

#hematology

Reference:

Ballas SK, Lieff S, Benjamin LJ, et al. Definitions of the phenotypic manifestations of sickle cell disease. Am J Hematol 2010; 85:6.

ILE

Q: What are the three mechanisms by which Intravenous Lipid Emulsion (ILE) Therapy works in toxicology?


Answer: The first question is to determine that if ingested drug/toxin molecule is lipophilic or not? If the answer is yes than ILE works via three mechanisms:

1. Lipid emulsion acts as a "lipid sink". It surrounds a lipophilic drug molecule making it ineffective.

2. The second and less well-known action is via the fatty acids present in ILE. It provides the myocardium with an extra energy source, enhancing its contractility leading to improved hemodynamics.

3. ILE works as a "lipid shuttle". It encapsulates the toxin and transports to the liver and kidney for metabolism.

#toxicology


References:

1. Gueret G, Pennec JP, Arvieux CC. Hemodynamic effects of intralipid after verapamil intoxication may be due to a direct effect of fatty acids on myocardial calcium channels. Acad Emerg Med 2007; 14:761.

2. Gosselin S, Hoegberg LC, Hoffman RS, et al. Evidence-based recommendations on the use of intravenous lipid emulsion therapy in poisoning(). Clin Toxicol (Phila) 2016; 54:899.

3. Jamaty C, Bailey B, Larocque A, et al. Lipid emulsions in the treatment of acute poisoning: a systematic review of human and animal studies. Clin Toxicol (Phila) 2010; 48:1. 

OCS

Q: You have been called to evaluate a patient's eyes who is on high PEEP. Nurse at the start of her shift noticed patient's eyelids tight and "rock hard". On exam, you found periorbital swelling, proptosis, diffuse subconjunctival hemorrhage, and inability to push the eye deeper into the orbit. What is your diagnosis?


Answer: Orbital compartment syndrome (OCS) 


OCS is an ophthalmologic emergency. Head of the bed should be immediately elevated to 45 degrees and Opthalmology should be called for immediate lateral canthotomy and inferior cantholysis. If an ophthalmology service is not available, a physician experienced with such procedure should take the charge, as permanent blindness is imminent with delay in care. Pressure on the optic nerve can cause irreversible ischemia. 

Classic findings of OCS are an acute onset of decreased vision, diplopia, and eye pain, which may be lacking in ICU patients, further increasing the risk of blindness without bedside staff even aware of it. Physical findings include periorbital swelling, an afferent pupillary defect, proptosis, diffuse subconjunctival hemorrhage, very tight eyelids (feel like rock hard), and an inability to push the eye deeper into the orbit, called as a tight orbit or decreased retropulsion. 

All attempts should be made to avoid an increase of OCS like decreasing PEEP to the point where hypoxemia can be sustained, avoiding cough, pain control, decreasing nausea/vomiting (OCS can induce it) and avoiding any cause which leads to increase intrathoracic or intraabdominal pressure.

#opthalmology
#ventilators


References:

1. Lima V, Burt B, Leibovitch I, et al. Orbital compartment syndrome: the ophthalmic surgical emergency. Surv Ophthalmol 2009; 54:441.  

2. Sun MT, Chan WO, Selva D. Traumatic orbital compartment syndrome: importance of the lateral canthomy and cantholysis. Emerg Med Australas 2014; 26:274.

Bivalirudin and HD

Q: Is Bivalirudin (Angiomax) dialyzable?

A) Yes
B) No


Answer: A

Bivalirudin is metabolized by many organs in the body including the kidney and liver. Bivalirudin dose should be lowered for infusion in patients who have severe renal insufficiency i.e., with CrCl less than 30 mL/minute. Bivalirudin can be hemodialyzed, so patients already on hemodialysis, paradoxically may require a higher dose to keep adequate aPTT.

#nephrology
#pharmacology
#hematology


References:

1. Warkentin TE, Greinacher A, Koster A. Bivalirudin. Thromb Haemost 2008; 99:830. 

2. Di Nisio M, Middeldorp S, Büller HR. Direct thrombin inhibitors. N Engl J Med 2005; 353:1028.

Sudden onset headache

Q: All of the following presents as a sudden-onset headache except? 

A) Subarachnoid hemorrhage (SAH)
B) Vertebral artery dissection
C) Acute angle-closure glaucoma
D) Pituitary apoplexy
E)  Herpetic meningitis


Answer: E

A sudden onset headache, particularly when it is described as the worst headache of life, and reaches maximal intensity within a few minutes, are all signs of serious central pathologies. The objective of this question is to highlight those headaches which are serious in nature but does not present in a classic 'sudden onset' presentations. These include herpetic or Lyme meningitis, cerebral venous sinus thrombosis, brain tumor, brain abscess, hypertensive encephalopathy, posterior reversible encephalopathy syndrome (PRES), and idiopathic intracranial hypertension.

#neurology


Reference:

Tabatabai RR, Swadron SP. Headache in the Emergency Department: Avoiding Misdiagnosis of Dangerous Secondary Causes. Emerg Med Clin North Am 2016; 34:695.

ASV

Q: ASV is a mode of ventilation that stands for?

A) Assisted support ventilation
B) Adaptive support ventilation


Answer: B

The objective of the above question is to understand this mode of ventilation by its nomenclature. As the name says "adaptive", it is a ventilatory mode that adapts (calculate/adjust) respiratory rate and inspiratory pressure to achieve targeted minute ventilation.

Although weak there is some data to suggest that ASV decreases the weaning of ventilator duration.

#ventilator
#pulmonary


References:

1. Arnal JM, Wysocki M, Nafati C, et al. Automatic selection of breathing pattern using adaptive support ventilation. Intensive Care Med 2008; 34:75. 

2. Kirakli C, Naz I, Ediboglu O, et al. A randomized controlled trial comparing the ventilation duration between adaptive support ventilation and pressure assist/control ventilation in medical patients in the ICU. Chest 2015; 147:1503.

iNO

Q: What is the major concern when inhaled nitric oxide (iNO) is administrated via nasal prong, face mask or Non-invasive positive pressure (NIPPV) mask?


Answer:  iNO and its derivatives NO2 have direct cytotoxic effects particularly to alveolar and vascular tissue. NO released into the environment can be potentially toxic. If iNO is administered by nasal prongs, face mask or NIPPV than it should be done in a well-ventilated area.

#pulmonary
#pharmacology


References:

1.Weinberger B, Laskin DL, Heck DE, Laskin JD. The toxicology of inhaled nitric oxide. Toxicol Sci 2001; 59:5. 

2. Narula P, Xu J, Kazzaz JA, et al. Synergistic cytotoxicity from nitric oxide and hyperoxia in cultured lung cells. Am J Physiol 1998; 274:L411. 

3. Gaston B, Drazen JM, Loscalzo J, Stamler JS. The biology of nitrogen oxides in the airways. Am J Respir Crit Care Med 1994; 149:538.