Thursday, February 22, 2018

Digoxin toxicity

Q: Patients with documented digoxin toxicity who receive Fab fragments should be observed in ICU for how long?

A) At least 24 hours
B) At least 48 hours
C) At least 72-96 hours
D) Once digoxin level is normalized
E) Once Fab fragment is received patient is safe to be monitored on Telemetry floor


Answer: C

Objective of above question is twofold:

1. Despite getting Fab fragments, recurrent digoxin toxicity with ventricular arrhythmia continue to occur for 72-96 hours  due to digoxin's large volume of distribution. This is particularly important in patients with renal dysfunction 1.

2. Once patient receives Fab fragments, laboratory cannot read digoxin level properly and any measurement for at least seven days would be erroneous. (Choice D) 2.


References:  

1. Renard C, Grene-Lerouge N, Beau N, et al. Pharmacokinetics of digoxin-specific Fab: effects of decreased renal function and age. Br J Clin Pharmacol 1997; 44:135. 

2.  Ujhelyi MR, Green PJ, Cummings DM, et al. Determination of free serum digoxin concentrations in digoxin toxic patients after administration of digoxin fab antibodies. Ther Drug Monit 1992; 14:147.

Wednesday, February 21, 2018

Adenosine in post transplanted heart

Q: Patients with the history of heart transplant have which kind of response to rapid infusion of Adenosine?

A) No response
B) Partial response
C) Suprasensitive response
D) unpredictable response


Answer: C

Patients with cardiac transplant history usually show a supersensitive response to adenosine. The effect of response to the drug can be threefold to fivefold. This is due to the fact that post heart transplant, the denervated donor atria, and ventricles demonstrate increased sensitivity to infusions of sympathomimetic amines.



References:


Ellenbogen KA, Thames MD, DiMarco JP, et al. Electrophysiological effects of adenosine in the transplanted human heart. Evidence of supersensitivity. Circulation 1990; 81:821.

Tuesday, February 20, 2018

Harvey-Bradshaw Index

Q: Harvey-Bradshaw Index (HBI) is a simplified derivative of which disease to determine the severity of disease?

A) Crohn's Disease Activity Index (CDAI) 
B) Severity of pneumonia index
C) ICU severity score
D) Mortality index from acute myocardial infarction
E) Post lung transplant mortality index


Answer: A

Harvey-Bradshaw Index (HBI) is a simplified derivative of the CDAI. It correlates well with CDAI. It can help ICU physicians to determine the level of urgency and choosing treatment modality. Calculators are easily available online.


Score of less than 5 on HBI is determined as clinical remission. HBI takes into account of

1. Patient sense of general well being in the last 24 hours
2. Patient report of abdominal pain in last 24 hours
3. Number of liquid stools in last 24 hours
4.  Finding of an abdominal mass
5.  Complications

CDAI is more extensive and complicated. It has four categories and takes into account

1. Patient reported stool pattern
2.  Average abdominal pain rating over seven days
3. General well being
4. Complications
5. Finding of an abdominal mass
6. Anemia and weight change

Severity goes up with score

1. Less than 150
2. Between 151 to 220
3. Between 221 to 450
4. Above 450 (Patients with severe symptoms despite glucocorticoids or biologic agents)


References:

1. Harvey RF, Bradshaw JM. A simple index of Crohn's-disease activity. Lancet 1980; 1:514.

2. Vermeire S, Schreiber S, Sandborn WJ, et al. Correlation between the Crohn's disease activity and Harvey-Bradshaw indices in assessing Crohn's disease severity. Clin Gastroenterol Hepatol 2010; 8:357.

Monday, February 19, 2018

Jolt accentuation of a headache

Q: Jolt accentuation of a headache on physical exam raises the possibility of

A) A retinal migraine
B) Meningitis
C) Intra-cranial mass
D) Cervical radiculopathy
E) Subarachnoid hemmorhage 


Answer: B

Although Brudzinski and the Kernig signs have been described as the classic for meningitis, jolt accentuation o a headache may be easier to perform and can be more sensitive 1. It is considered positive if accentuation of a headache occurs by horizontal rotation of the head at a frequency of 2-3/sec. This does not confirm or rule out 2 the diagnosis of meningitis but may make the patient eligible for a lumbar puncture (LP).


References:

1. Uchihara T, Tsukagoshi H. Jolt accentuation of headache: the most sensitive sign of CSF pleocytosis. Headache 1991; 31:167. 


2. Tamune H, Takeya H, Suzuki W, et al. Absence of jolt accentuation of headache cannot accurately rule out meningitis in adults. Am J Emerg Med 2013; 31:1601.

Sunday, February 18, 2018

Postprandial hypotension in ESRD patients

Scenario; 62-year-old male with End Stage Renal Disease (ESRD) is admitted in ICU for community-acquired pneumonia. The patient is responding to antibiotics. Patient in ICU previously had two episodes of hypotension while in hemodialysis (HD) session, requiring stoppage of HD and infusion of a fluid bolus. Today Nephrology service wrote orders to hold food before and while the patient is in HD session?


Explanation: Studies have shown that peripheral vascular resistance (PVR) drops 20 to 120 minutes after the ingestion of food, and this effect may be pronounced in chronic ESRD patients, on HD due to autonomic dysfunction. This is one easy trick which can be useful in ICU :)



References:

1. Barakat MM, Nawab ZM, Yu AW, et al. Hemodynamic effects of intradialytic food ingestion and the effects of caffeine. J Am Soc Nephrol 1993; 3:1813. 

2. Sherman RA, Torres F, Cody RP. Postprandial blood pressure changes during hemodialysis. Am J Kidney Dis 1988; 12:37. 

3. Kearney MT, Cowley AJ, Stubbs TA, et al. Depressor action of insulin on skeletal muscle vasculature: a novel mechanism for postprandial hypotension in the elderly. J Am Coll Cardiol 1998; 31:209.

Saturday, February 17, 2018

enteral formula for chylous situations

Q: Which of the following enteral formula may be useful in chylothorax or chylous ascites? 

A) Standard
B) Concentrated 
C) Predigested
D) Patient should be kept NPO
E) Only nocturnal enteral nutrition 


Answer: C

Predigested enteral nutrition is also known as a semi-elemental or elemental formula. The main focus in this formula is on decreased fat with increased medium-chain triglycerides (MCTs). 
Also, the protein is hydrolyzed to short-chain peptides and a less complex form of carbohydrate is included. MCTs can't enter lymphatic capillaries in the small intestine and are advocated in patients with thoracic duct leak, chylothorax or chylous ascites. They are also recommended in malabsorptive syndromes, short gut syndromes, unresponsive gut to pancreatic enzymes supplements, and persistent diarrhea from standard enteral nutrition in ICU. As the name implies, they are like a digested form of enteral nutrition and better tolerated by the digestive system.

Abovesaid, evidence for its regular use in ICU is still weak.


References:

Seres DS, Ippolito PR. Pilot study evaluating the efficacy, tolerance and safety of a peptide-based enteral formula versus a high protein enteral formula in multiple ICU settings (medical, surgical, cardiothoracic). Clin Nutr 2017; 36:706.

Friday, February 16, 2018

Warfarin

Q: All of the following can be the  side-effects of warfarin except?

A) Bleeding 

B) Skin necrosis 
C) Teratogenicity during pregnancy
D) Cholesterol embolization 
E) Vascular de-calcification


Answer:  E

Instead of vascular de-calcification, actually vascular calcification has been seen in patient on warfarin therapy. It can be seen in aortic valve, coronary arteries, femoral artery. The mechanism of action is the inhibition of a vitamin K dependent matrix Gla protein. It's correlation with clinical outcomes such as stroke or coronary events is still not validated.



References:

1. Koos R, Mahnken AH, M├╝hlenbruch G, et al. Relation of oral anticoagulation to cardiac valvular and coronary calcium assessed by multislice spiral computed tomography. Am J Cardiol 2005; 96:747. 

2. Koos R, Krueger T, Westenfeld R, et al. Relation of circulating Matrix Gla-Protein and anticoagulation status in patients with aortic valve calcification. Thromb Haemost 2009; 101:706. 

3. Rennenberg RJ, van Varik BJ, Schurgers LJ, et al. Chronic coumarin treatment is associated with increased extracoronary arterial calcification in humans. Blood 2010; 115:5121. 


Thursday, February 15, 2018

Drug level monitoring in ICU

Q: End-stage renal disease (ESRD) and AKI can also effect hepatic drug metabolism?

A) True
B) False


Answer: True

An important but not always appreciated fact in the ICU is that liver drug metabolism may also change in patients who develop acute kidney injury (AKI). Overall, end-stage renal disease (ESRD) and AKI both reduce hepatic drug metabolism. It calls for close vigilance of drugs level monitoring, irrespective of route of excretion.


Reference:

1. Vilay AM, Churchwell MD, Mueller BA. Clinical review: Drug metabolism and nonrenal clearance in acute kidney injury. Crit Care 2008; 12:235. 

Wednesday, February 14, 2018

Hyperfusion syndrome after CEA

Q: Why it is important to have a tight blood pressure control after carotid endarterectomy (CEA)?


Answer: Hypertension is a predecessor of the hyperfusion syndrome after CEA. Though it is not a common sequela of post CEA, but it can be devastating causing intracerebral hemorrhage (ICH) and seizures. It mostly occurs in first 2 weeks of the procedure. This is due to the restoration of blood flow within the previously hypoperfused cerebral hemisphere, where vessels may have lost the capacity to autoregulate. Peri and post operative BP control can prevent that. Risk factors are high-grade stenosis, carotid lesion, and  recent stroke. Clinical sign is ipsilateral headache to the revascularized side which improves at upright posture. Other clinical signs are focal motor seizures, and postictal Todd's paralysis. 


References: 

1.  Coutts SB, Hill MD, Hu WY. Hyperperfusion syndrome: toward a stricter definition. Neurosurgery 2003; 53:1053. 

2. Bouri S, Thapar A, Shalhoub J, et al. Hypertension and the post-carotid endarterectomy cerebral hyperperfusion syndrome. Eur J Vasc Endovasc Surg 2011; 41:229. 

3. Piepgras DG, Morgan MK, Sundt TM Jr, et al. Intracerebral hemorrhage after carotid endarterectomy. J Neurosurg 1988; 68:532. 

4. Karapanayiotides T, Meuli R, Devuyst G, et al. Postcarotid endarterectomy hyperperfusion or reperfusion syndrome. Stroke 2005; 36:21.

Tuesday, February 13, 2018

Akinetic mutism

Q: Akinetic mutism is due to injury to which part of the brain?

A) Temporal lobe
B) Parietal lobe
C) Frontal lobe
D) Occipital lobe
E) It is a psychiatric phenomenon


Answer: C

The objective of above question is to highlight a relatively less known phenomenon, akinetic mutism after a neurological insult. Due to injury to the frontal lobe, a patient does not initiate speech or movements. 

In akinetic mutism, a patient is not paralyzed but lack willingness. Alertness is present and patients' eyes may follow their observer or they may respond to audio clues. There are two kinds of akinetic mutism described. 1) Frontal or hyperpathic akinetic mutism as described above 2) Mesencephalic or somnolent akinetic mutism due to damage to the midbrain, where vertical gaze palsy and ophthalmoplegia can usually be demonstrated.


This is completely a distinct phenomenon. After an event of neural insult, a careful determination should be performed to differentiate between coma, persistent vegetative state, brain death, locked-in syndrome (coma vigilante) and dementia, as they all have different management and outcomes.

Treatment with intravenous magnesium sulfate has been said to be beneficial.



References:

Laureys S, Owen AM, Schiff ND. Brain function in coma, vegetative state, and related disorders. Lancet Neurol 2004; 3:537.

Nagaratnam, Nages; Kujan Nagaratnam; Kevin Ng; Patrick Diu (2004). "Akinetic mutism following stroke". Journal of Clinical Neuroscience. 11 (1): 25–30.Rozen, Todd (2012).

 "Rapid resolution of akinetic mutism in delayed post-hypoxic leukoencephalopathy with intravenous magnesium sulfate". Neurorehabilitation. 30 (4): 329–332

Monday, February 12, 2018

Dialysis Catheter which did not work (case report)

Case:

A 66YO man admitted for a septic shock with acute kidney failure. A dialysis catheter was placed in the left internal jugular vein using ultrasound guidance. Abnormal positioning of the catheter was suspected after technical difficulty in initiating dialysis.



Reference:

Wissanji, T., Wang, H.T. & Marquis, F. Intensive Care Med (2018). https://doi.org/10.1007/s00134-018-5058-3

Sunday, February 11, 2018

Serotonin Syndrome

Q: All of the following are relatively contra-indicated in Serotonin Syndrome (SS) except?

A) Cyproheptadine
B) Propranolol
C) Bromocriptine
D) Dantrolene
E) Chlorpromazine



Answer: A

Out of all of the above, Cyproheptadine is established as an antidote for SS.  Cyproheptadine is a histamine-1 receptor antagonist as well as has anticholinergic activity. Benzodiazepines can also be used to control agitation.

Olanzapine is also recommended to counter SS but data is not convincing.

Chlorpromazine may increase hyperthermia. 

Interestingly in SS, monitoring of tachycardia is used to gauge the effectiveness of treatment. Propranolol can mask tachycardia. Also, it can induce prolong hypotension due to it's prolong half life.

 Bromocriptine is a serotonin agonist! - and should be avoided.

Dantrolene has no role in SS.


References:

1. Boyer EW, Shannon M. The serotonin syndrome. N Engl J Med 2005; 352:1112.


2. Graudins A, Stearman A, Chan B. Treatment of the serotonin syndrome with cyproheptadine. J Emerg Med 1998; 16:615. 

3. Gillman PK. The serotonin syndrome and its treatment. J Psychopharmacol 1999; 13:100. 

4. McDaniel WW. Serotonin syndrome: early management with cyproheptadine. Ann Pharmacother 2001; 35:870.

Saturday, February 10, 2018

Negative U wave on EKG

Q: Negative U wave on EKG during exercise testing correlates with stenosis of which coronary vessels?


A) The left main
B) Left anterior descending coronary artery (LAD)
C) Posterior descending artery
D) A and B
E) All of the above




Answer: D


U waves on EKG are usually positive deflections and best visible on leads V2 to V4. They are well known in clinical practice due to their association with hypokalemia and intracranial hemorrhage. U wave's polarity may reverse during myocardial ischemia. Negative U waves during exercise stress test is highly suggestive of ischemia from left main or LAD artery.

Friday, February 9, 2018

Undesirable effects of mechanical ventilation

Q: All of the following are the effects of Positive Pressure Ventilation (PPV) except? 

A) Decreased dead space 
B) Reduced intraparenchymal shunt
C) Diaphragmatic dysfunction 
D) Respiratory muscle atrophy 
E) Impaired mucociliary motility


Answer:  A

Prolonged positive pressure ventilation is associated with many undesirable effects including all of the following except choice A. Positive pressure ventilation increases ventilation (V) in alveoli that do not have a corresponding increase in perfusion (Q). It causes increased V/Q mismatch and increased dead space. The ultimate effect could become evident as hypercapnia in Arterial-Blood-Gases (ABGs).

Thursday, February 8, 2018

End of life care _SUPPORT study

Q: "Maintaining a sense of humor" is part of a good death process?

A) True
B) False


Answer: True

According to SUPPORT (Study to Understand Prognosis and Preferences for Outcomes and Risks of Treatments) study in which older adults facing the end of life offered insight into a good death as they experienced their own dying, there were 19 expectations / recommendations /desires divided into five components

1. Care related to symptoms and personal care 
2. Being prepared for death 
3. Achieving a sense of completion 
4. Being treated as a whole person
5. Relating to family, society, care providers, and transcendent

"Maintaining a sense of humor" is considered as one of the part from dying patients in #4 component.

Reference:

Steinhauser KE, Christakis NA, Clipp EC, et al. Factors considered important at the end of life by patients, family, physicians, and other care providers. JAMA 2000; 284:2476.

Wednesday, February 7, 2018

Temperature measurement in hypothermic patients

Q: Which of the following method is most reliable to measure the rewarming phase in a severely hypothermic patient who is intubated?

A) Rectal
B) Bladder
C) Infra-red temporal artery
D) Lower one-third of the esophagus
E) Axillary


Answer: D

In patients with severe hypothermia lower one-third of the esophagus, and to be precise 24 cm below the larynx, is the most reliable method to track the rewarming phase. This area provides the best surrogate of the cardiac temperature. Upper one-third of the esophagus may be falsely elevated due to humidified (heated) oxygen in the endotracheal-tube (ETT). Though rectal and bladder probes are commonly used and good for mild to moderate hypothermia, but they lag behind in the rewarming phase. Axillary and temporal artery measurement of temperature are external to the body and should not be used.



Reference:

Danzl D. Accidental hypothermia. In: Wilderness Medicine, 6th ed, Auerbach PS (Ed), Elsevier, Philadelphia 2012. p.115.

Tuesday, February 6, 2018

Pad size on cardioversion

Q: During external electric cardioversion which size of electrode pad is preferred (select one)

A) Bigger size
B) Smaller size


Answer: A

Larger size of electrode pad (usually 12-13 cm in diameter) provides larger paddle surface area, which results in decrease resistance and increase current and may cause less cardiac muscle necrosis.



References:

1. Thomas ED, Ewy GA, Dahl CF, Ewy MD. Effectiveness of direct current defibrillation: role of paddle electrode size. Am Heart J 1977; 93:463. 

2. Ewy GA, Horan WJ. Effectiveness of direct current defibrillation: role of paddle electrode size: II. Am Heart J 1977; 93:674. 

3. Dahl CF, Ewy GA, Warner ED, Thomas ED. Myocardial necrosis from direct current countershock. Effect of paddle electrode size and time interval between discharges. Circulation 1974; 50:956. 

Monday, February 5, 2018

Classic phrase for embolic stroke

Q: Stroke precipitated with a history of "getting up at night to urinate" is classic of which kind of stroke?

A) Intracerebral hemorrhage (ICH)
B) Subarachnoid hemorrhage (SAH)
C) Thrombotic stroke
D) Embolic stroke
E) Transient ischemic attack (TIA)


Answer: D

In contrast to ICH/SAH which are classic to precipitate secondary to sexual or physical activity, embolic stroke is classic with the history of precipitated by "getting up at night to urinate".  Some patients may report activity like forceful sneezing or cough. Also, embolic strokes in contrast to thrombotic strokes are described with three of the following characteristics:
  • tends to occur suddenly 
  • maximal at onset
  • rapid recovery
Beside general risk factors for atherosclerosis like age, smoking, diabetes mellitus, etc., history of valvular heart disease or atrial fibrillation is more common in this subgroup of stroke.


Sunday, February 4, 2018

Pupillary reaction through the different stages of hepatic encephalopathy

Q: How the pupillary reaction progresses through the different stages of hepatic encephalopathy?


Answer: 

Close monitoring of pupillary changes is an integral and essential part of the management of hepatic encephalopathy as it signifies the level of increased intracranial pressure. 
  • A normal response = grade I encephalopathy
  • Hyperresponsive = grade II to III encephalopathy
  • Slowly responsive = grade III to IV encephalopathy
  • Fixed and dilated = probable brainstem herniation


References / further read:

1. Shawcross DL, Wendon JA. The neurological manifestations of acute liver failure. Neurochem Int. 2012 Jun;60(7):662-71.

2. Eelco F.M. Wijdicks, M.D., Ph.D. .N Engl J Med 2016; 375:1660-1670

Saturday, February 3, 2018

Toxoplasmosis in Post Heart Transplant

Q: In which of the following, there is the highest incidence of Toxoplasmosis, post Solid Organ Transplants (SOT)?  

A) Kidney
B) Liver
C) Heart

D) Pancrease
E) Lung


Answer: C

Out of all, the post cardiac transplant patients have shown to have the highest incidence of toxoplasmosis. This may be due to the fact that parasitic cysts can reside in the myocardium. Often it occurs within 90 days of the transplantation and presents with mental status change (encephalopathy).  Hallmark of this disease with ring-enhancing lesions can be seen on MRI of the brain.


Reference:

Munoz P, Valerio M, Palomo J, et al. Infectious and non-infectious neurologic complications in heart transplant recipients. Medicine (Baltimore). 2010;89(3):166–175

Friday, February 2, 2018

Ocular Sonography in Elevated ICP

Q: How ocular sonography can be of  help in Neuro-Critical-Care?



Answer: Biggest advantage of ocular sonography is that it is non-invasive. It can measure the diameter of  optic nerve sheath, which correlates with intracranial pressure (ICP). Literature is conflicting in establishing the cutoff point but diameter above 5.5 mm is found to have a high sensitivity and specificity for ICP of >20 cm H2O.


References:


1. Amini A, Kariman H, Arhami Dolatabadi A, Hatamabadi HR, Derakhshanfar H, Mansouri B, et al. Use of the sonographic diameter of optic nerve sheath to estimate intracranial pressure. Am J Emerg Med. 2013;31:236–9. 

2. Soldatos T, Karakitsos D, Chatzimichail K, et al. Optic nerve sonography in the diagnostic evaluation of adult brain injury. Crit Care 2008; 12:R67. 

3. Dubourg J, Javouhey E, Geeraerts T, et al. Ultrasonography of optic nerve sheath diameter for detection of raised intracranial pressure: a systematic review and meta-analysis. Intensive Care Med 2011; 37:1059. 

Thursday, February 1, 2018

Seizure in mushroom poisoning

Q: What is the drug of choice in a patient who get admitted to ICU with poisonous mushroom ingestion, develop seizures which does not respond to standard anti-seizure medications? 


Answer: Pyridoxine 

Gyromitrin containing mushrooms are more prone to cause seizures. Usually benzodiazepines works well to control seizures. But if patient does not respond to standard anticonvulsants, pyridoxine is the next choice. Usual dose is 5 grams. Pyridoxine works via its involvement in synthesis of GABA within CNS and works well if administrated with benzodiazepines. 


 Reference: 

 Michelot D, Toth B. Poisoning by Gyromitra esculenta--a review. J Appl Toxicol 1991; 11:235.

Wednesday, January 31, 2018

A violent patient in ICU

Q: A violent patient in ICU with a psychiatric disorder or drug/alcohol withdrawal should be asked directly: "Do you feel like hurting yourself or others?"

A) True
B) False


Answer: True

It is both helpful and respectful to have an honest and non-threatening behavior towards a patient who tends toward violence. Addressing violence directly helps!

Also, many other non-pharmacological recommendations may help like friendly gestures,  avoiding direct eye contact, not to approach the patient from behind,  standing at least two arm's lengths away, avoiding argument or giving commands.


References: 

1. Hill S, Petit J. The violent patient. Emerg Med Clin North Am 2000; 18:301. 

2. Richmond JS, Berlin JS, Fishkind AB, et al. Verbal De-escalation of the Agitated Patient: Consensus Statement of the American Association for Emergency Psychiatry Project BETA De-escalation Workgroup. West J Emerg Med 2012; 13:17.

Tuesday, January 30, 2018

Use of fiber in patients on vasopressor

Q: Fiber should be added to the enteral formulae in critically ill patients who are on vasopressors.

A) True
B) False


Answer:  False

Evidence for the regular use of fiber in critically ill patients is very weak and should be avoided. It can be used on a trial basis in patients who develop persistent motility problem secondary to enteral nutrition. Patients on vasopressors may develop bezoars from fiber and should be added with caution.


References / further reading:

1. McIvor AC, Meguid MM, Curtas S, et al. Intestinal obstruction from cecal bezoar; a complication of fiber-containing tube feedings. Nutrition 1990; 6:115. 

2. Dobb GJ, Towler SC. Diarrhoea during enteral feeding in the critically ill: a comparison of feeds with and without fibre. Intensive Care Med 1990; 16:252.  

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

Monday, January 29, 2018

PET scan and Takotsubo Cardiomyopathy

Q: "Inverse flow metabolism mismatch" on positron emission tomography (PET Scan) is the hallmark of which cardiac disease?

A) Marfan syndrome
B) Hypertrophic Cardiomyopathy
C) Pericarditis
D) Stress (takotsubo) cardiomyopathy
E) Dilated cardiomyopathy secondary to amyloidosis



Answer:  D

In recent literature PET scan has been advocated to confirm the diagnosis of stress cardiomyopathy. As expected, PET scan in stress cardiomyopathy shows a discrepancy between normal perfusion and reduced glucose utilization in dysfunction regions. This is referred as an "inverse flow metabolism mismatch".


Reference:


Testa M, Feola M. Usefulness of myocardial positron emission tomography/nuclear imaging in Takotsubo cardiomyopathy. World J Radiol 2014; 6:502.

Sunday, January 28, 2018

A Note on Abdomen-Brain Connection

A Note on Abdomen-Brain Connection 

Not embraced by everyone and one of the controversial indication to perform open abdomen is refractory intracranial hypertension. It is presumed that the decompression of abdomen by keeping abdomen open lowers the venous pressures and may augment venous outflow from the head and consequently decrease the intracranial pressure.



Reference:

Joseph DK, Dutton RP, Aarabi B, Scalea TM. Decompressive laparotomy to treat intractable intracranial hypertension after traumatic brain injury. J Trauma 2004; 57:687.

Saturday, January 27, 2018

Atropine test for Brain Death Determination

Q: The atropine test is considered positive for brain death determination if the heart rate response to intravenous injection of 2-3 mg atropine shows 

A) an increase in heart rate less than 3 percent
B) an increase in heart rate less than 10 percent
C) a decrease in heart rate more than 3 percent
D) a decrease in heart rate more than 10 percent
E) Patient develops ventricular tachycardia



Answer: A


The atropine test assesses bulbar parasympathetic activity on heart activity in brain-dead patients. 2-3 mg of atropine is injected under continuous monitoring of the EKG over 10 minutes. The test is considered negative if heart rate is not increased by more than 3%.


References:

1. Siemens P, Hilger HH, Frowein RA. Heart rate variability and the reaction of heart rate to atropine in brain dead patients. Neurosurg Rev 1989; 12 Suppl 1:282.

2. Huttemann E, Schelenz C, Sakka SG, et al. Atropine test and circulatory arrest in the fossa posterior assessed by transcranial Doppler. Intensive Care Med. 2000;26:422–5.

3. Cardan C, Roth A, Biro J. The atropine test in the assessment of brain death. Rev Chir Oncol Radiol O R L Oftalmol Stomatol Chir. 1983;32:393–7

Friday, January 26, 2018

Armored Endotracheal Tube

Q: Give at least three characteristics of an Armored endotracheal tube (A-ETT) popularly known as a 'reinforced endotracheal tube'?


Answer: A reinforced ETT is advocated when there is a concern for tracheal compression. It has a metal wire coil embedded in the wall of the tube.

1. It has more flexibility but less collapsibility.

2. The tube connector of armored tubes is not detachable (unlike standard ETT).
3. As they are relatively more flexible, it is very hard to intubate without a stylet. 

It is an excellent replacement for ETT when more flexibility but less collapsibility (i.e resistance to occlusion) is desired such as in;


  • fiberoptic intubation
  •  intubation through a tracheotomy 
  • upper body surgeries
  • when a patient requires prone position

Thursday, January 25, 2018

non-long-bone-trauma causes of fat embolism

Q: Give ten examples of conditions causing 'fat embolism' other than long bone trauma? 

Answer: Though 'fat embolism' is mostly due to long bone traumas but many non-traumatic conditions (though uncommon) can be the cause of fat embolism. List is long but few ICU related causes may be (also see references):
  1. Chest compressions with or without rib fractures 
  2. Burns 
  3. Pancreatitis 
  4. Osteomyelitis 
  5. Prolonged steroid therapy 
  6. Sickle cell hemoglobinopathies 
  7. Lipid infusion 
  8. Cyclosporin A solvent 
  9. Intraoperative cell salvage 
  10. Cardiopulmonary bypass


References / further reading:

1. de Lima E Souza R, Apgaua BT, Milhomens JD, et al. Severe fat embolism in perioperative abdominal liposuction and fat grafting. Braz J Anesthesiol 2016; 66:324. 

2. Jacob S, Courtwright A, El-Chemaly S, et al. Donor-acquired fat embolism syndrome after lung transplantation. Eur J Cardiothorac Surg 2016; 49:1344. 

3. Schrufer-Poland T, Singh P, Jodicke C, et al. Nontraumatic Fat Embolism Found Following Maternal Death after Cesarean Delivery. AJP Rep 2015; 5:e1. 

4. Schonfeld SA, Ploysongsang Y, DiLisio R, et al. Fat embolism prophylaxis with corticosteroids. A prospective study in high-risk patients. Ann Intern Med 1983; 99:438. 

5. Garza JA. Massive fat and necrotic bone marrow embolization in a previously undiagnosed patient with sickle cell disease. Am J Forensic Med Pathol 1990; 11:83. 

6. Levine M, Skolnik AB, Ruha AM, et al. Complications following antidotal use of intravenous lipid emulsion therapy. J Med Toxicol 2014; 10:10. 


Wednesday, January 24, 2018

Local anesthesia in CVC

Q: During inserting non-tunneled Central Venous Catheter (CVC) in ICU, it is recommended to infiltrate a large amount of local anesthesia into subcutaneous (SC) tissues. 

A) True
B) False


Answer: B

Infiltrating skin and SC tissues with local anesthesia is needed prior to inserting CVC in ICU but large infiltration can cause two problems.

1.  a large infiltration of local anesthesia in the SC tissue will distort anatomical landmarks (particularly making it difficult if no bedside ultrasound is available).

2. A  large infiltration of local anesthesia in the SC tissue may compress vein making access more difficult, particularly in dehydrated patients.

Tuesday, January 23, 2018

Use of cryoprecipitate in uremic bleeding

Q: Which of the following can be used in bleeding suspected secondary to uremia?

A) Dialysis 
 B) Desmopressin (DDAVP) 
 C) Estrogen 
D) Cryoprecipitate 
 E) All of the above 


 Answer: E

Objective of above question is to highlight the role of Cryoprecipitate in uremic bleeding. Dialysis, Estrogen, DDAVP and correction of anemia are known to help in uremic bleeding. Use of cryoprecipitate in this regard is less well known. It may be a very useful information in post surgical patients with baseline renal insufficiency, who remain unresponsive to DDAVP. It can start it's effect within one hour of infusion to shorten the bleeding time. Exact mechanism of action is not known but it is suspected that cryoprecipitate carries substances that enhance platelet aggregation, such as factor VIII:von Willebrand factor multimers or fibrinogen. 


Reference:

Janson PA, Jubelirer SJ, Weinstein MJ, Deykin D. Treatment of the bleeding tendency in uremia with cryoprecipitate. N Engl J Med 1980; 303:1318.

Monday, January 22, 2018

Spironolactone in CHF

Q: Which of the following is the proposed mechanism of action causing beneficial effects of the aldosterone-receptor blocker (Spironolactone) in congestive heart failure?

A) Averting sodium retention
B) Averting myocardial fibrosis
C) Averting potassium loss
D) increasing the myocardial uptake of norepinephrine
E) All of the above


Answer: E

Mechanism of action of an aldosterone-receptor blocker is complex. Some effects are well known Like Choices A and C. Objective of the above question is to highlight their role by averting myocardial fibrosis (Choice B). It reduces the risk of sudden death from arrhythmias. Also, myocardial uptake of norepinephrine (choice D) has been demonstrated in the animal models.


References:

1. Pitt B et al. The effect of spironolactone on morbidity and mortality in patients with severe heart failure. Randomized Aldactone Evaluation Study Investigators. N Engl J Med. 1999 Sep 2;341(10):709-17.

2. Buss SJ et. al. Spironolactone preserves cardiac norepinephrine reuptake in salt-sensitive Dahl rats. Endocrinology. 2006 May;147(5):2526-34.