Q: 52 year old male presented to ER with chest pain radiating to back. Which one blood test may rule out Aortic dissection?

Answer:  Negative D-Dimer

A D-dimer <0.1 µg/mL will exclude Acute Aortic Dissection in all cases.

Reference:

D-dimer in ruling out acute aortic dissection: a systematic review and prospective cohort study - Eur Heart J (2007) 28 (24): 3067-3075.

Q: How you define Bulla(e) and Giant bulla(e) in lung?

Answer:

Bulla(e): Larger than 2 cm in distended state

Giant bulla(e):  Bulla larger than one third of the hemithorax size and compression of adjacent lung parenchyma

Reference:


Waseem M, Jones J, Brutus S, et al. Giant bulla mimicking pneumothorax. J Emerg Med 2005;29:155-158.

Endoscopic Lung Volume Reduction

Endoscopic Lung Volume Reduction

Further reading: Endoscopic Lung Volume Reduction

Link: http://toraks.org.tr/uploadFiles/book/file/2422011175827-169175.pdf

(Basics)

Q: Formula for Mean Arterial Pressure (MAP) is  

MAP = [(2 x diastolic)+systolic] / 3

What is the logic behind it?

Answer:  Diastole counts twice as much as systole because 2/3 of the cardiac cycle is spent in diastole. (Something very simple but essential to know!)

Arterial line vs cuff Blood Pressure

Arterial catheterization (AC) is commonly used in critically ill patients to monitor blood pressure. In Critical care literature, there is a never ending debate about its co-relationship with cuff based blood pressure. In one recent small work, relationship between cuff- and AC-measured BPs in 34 patients was investigated.

A total of 1,363 paired arterial and cuff BP readings (13-82 per patient) were measured within 1 to 2 min and recorded by bedside nurses.

Overall, 18.9% of the paired systolic BP readings differed by at least 20 mm Hg, and 29.1% of paired diastolic BP readings differed by at least 10 mm Hg.

To adjust for potential clustering of measurements, bootstrap Bland-Altman analysis averaged over 5,000 replications yielded similar results to unclustered analyses for systolic BP (bias, 1.2 mm Hg; 95% LOA, −35.7 to +38.0 mm Hg) and diastolic BP (bias, −1.2 mm Hg; 95% LOA, −24.9 to +22.4 mm Hg).

Editors' note: Good bedside practice is to remove arterial line as soon as its not needed!

Reference and further reading:

1. Daniel Horowitz, MD; Yaw Amoateng-Adjepong, MD, PhD; Stuart Zarich, MD; Allan Garland, MD; Constantine A. Manthous, MD, FCCP - Arterial Line or Cuff BP? - Chest. 2013;143(1):270-271.

2. Garland A, Connors AF Jr. Indwelling arterial catheters in the intensive care unit: necessary and beneficial, or a harmful crutch?. Am J Respir Crit Care Med. 2010;182(2):133-134.

 
 
 
 

Q: How much is the pressure usually inflated in the arterial line pressure bag?

Answer: 300 mmHg

In arterial line monitoring, keeping pressure bag inflated to 300 mm Hg, keeps line patent and infuses saline 3-5ml /hr, which prevents dampening of traces and prevents clot formations. Deflation of bag will result in retrograde blood flow.  

How to setup an Arterial line transducer

 http://youtu.be/vJ_anWmQbUM

 Q: Which 2 relatively non-pharmacologic tricks can work in intractable hiccups in ICU?

Answer:

1. Give 2 ml Nebulised 0.9% saline over 5 minutes. It helps to relieve hiccup by pharyngeal stimulation.

2. Give Peppermint Water. Peppermint water helps by relaxing the lower oesophageal  sphincter.

Reference:

Twycross R, Wilcock A. - Symptom Management in Advanced Cancer. 3rd Edt. Radcliffe Medical Press. 2008

Q: Haloperidol (Haldol) can be helpful in which 2 non-central (CNS) conditions

Answer:

Haldol can be be tried if needed in ICU for

• Treatment of severe nausea and vomitting resulting likewise from postoperative care or adverse effects from radiation and chemotherapy.
• Treatment of intractable hiccups

 Q: What are the normal QTc intervals in hospitalized patients?

Answer:

According to a scientific statement from the American College of Cardiology (ACC) and the Heart Rhythm Society (HRS), the normal value for QTc in general population is: 

• below 450ms for men and
• below 460ms for women

But in a recent ACC consensus document an expert writing group suggest that in a hospital setting the upper limit be raised to the 99th percentile of normal:

• 470ms in males and
• 480 ms in females

(In any case, QTc more than 500ms is considered highly abnormal).

References:

1. Rautaharju PM, Surawicz B, Gettes LS, Bailey JJ, Childers R, Deal BJ, Gorgels A, Hancock EW, Josephson M, Kligfield P, Kors JA, Macfarlane P, Mason JW, Mirvis DM, Okin P, Pahlm O, van Herpen G, Wagner GS, and Wellens H. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology. Circulation 2009 Mar 17; 119(10) e241-50.

2. Drew BJ, Ackerman MJ, Funk M, Gibler WB, Kligfield P, Menon V, Philippides GJ, Roden DM, and Zareba W. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. J Am Coll Cardiol 2010 Mar 2; 55(9) 934-47.

Q: While administrating Procainamide, what is the cut off point to stop it depending on EKG criteria?

Answer: The QRS complex widens by 50% or more

Procainamide has a prolong action on cardiac muscles, particularly due to its metabolite N-acetylprocainamide (NAPA), which is also approximately equipotent with the parent drug as an antiarrhythmic agent. But to be of notice, NAPA has an elimination half-life about twice that of procainamide.

Procainamide should be discontinued when

• dysrhythmia is suppressed, or
• if hypotension ensues, or
• the QRS complex widens by 50% or more, or 
• the maximum dose is achieved.

 Q: Which drug works best for Ventricular fibrillation resulting from hypothermia?

Answer: Bretylium

Ventricular fibrillation in a hypothermic patient is a very frustrating and desperate event. Defibrillation is usually ineffective. Recommendation is to attempt a round of chemical conversion with intravenous bretylium accompanied by CPR until active rewarming can be done to perform successful defibrillation.

References:

1. Murphy K, Nowak RM, Tomlanovich MC. Use of bretylium tosylate as prophylaxis and treatment in hypothermic ventricular fibrillation in the canine model. Ann Emerg Med. Oct 1986;15(10):1160-6.
2. Vachiery JL, Reuse C, Blecic S, Contempre B, Vincent JL. Bretylium tosylate versus lidocaine in experimental cardiac arrest. Am J Emerg Med. Nov 1990;8(6):492-5
3. Buckley JJ, Bosch OK, Bacaner MB. Prevention of ventricular fibrillation during hypothermia with bretylium tosylate. Anesth Analg. Jul-Aug 1971;50(4):587-93

On Hypothermia

Following is a generally witnessed clinical response of body as temperature (in centigrade) changes

• {37} Normal oral temperature
• {36} Metabolic rate increased
• {35} Maximum shivering seen/impaired judgment
• {33} Severe clouding of consciousness
• {32} Most shivering ceases and pupils dilate
• {31} Blood pressure may no longer be obtainable
• {28~30}
  • Severe slowing of pulse/respiration
  • Increased muscle rigidity
  • Loss of consciousness
  • Ventricular fibrillation
• {27}
• Loss of deep tendon. skin and capillary reflexes
• Patients appear clinically dead
• Complete cardiac standstill

  

Q: What is the theoretical basis of inducing "Barb-Coma"?

Answer:

A barbiturate-induced coma, commonly called barb coma, is a temporary coma induced by a controlled administration of a barbiturate drug, usually pentobarbital or thiopental. Barbiturate comas are used in various settings in neuro ICUs to protect the brain like in persistent intra-cranial hypertension, resistant status epilepticus etc.

Barbiturates reduce the metabolic rate of brain tissue, as well as the cerebral blood flow. With these reductions, the blood vessels in the brain narrow, decreasing the amount of space occupied by the brain, and hence the intracranial pressure.

Also, about 55% of the glucose and oxygen utilization by the brain is meant for its electrical activity and the rest for all other activities such as metabolism. When barbiturates are given to brain injured patients for induced coma, they act by reducing the electrical activity of the brain, which in theory reduces the metabolic and oxygen demand.

Addendum:

Barbiturate (pentobarbital) coma protocol from Vanderbilt University Medical Center  (click here)

Link: http://www.mc.vanderbilt.edu/surgery/trauma/Protocols/VUMC%20Pentobarbital%20Coma%20Protocol.pdf

References:

1. Use of barbiturates in the control of intracranial hypertension". Journal of Neurotrauma (The Brain Trauma Foundation) 17 (6–7): 527–30. Jun-July 2000. 
2. Schalén, W; Sonesson B, Messeter K, Nordström G, Nordström CH (1992). "Clinical outcome and cognitive impairment in patients with severe head injuries treated with barbiturate coma". Acta Neurochir 117 (3–4): 153–9.

  

Q: What is an antagonist of Meperidine (Demerol)?


Answer: Naloxone

The narcotic antagonist, naloxone, is a specific antidote against respiratory depression which may result from over-dosage or unusual sensitivity to meperidine. But an antagonist should not be administered in the absence of clinically significant respiratory or cardiovascular depression, and other supportive treatments should be instituted like oxygen, IVF and others.

Remember, in an individual physically dependent on meperidine by chronic use, the administration of the usual dose of a naloxone may precipitate an acute withdrawal syndrome. If an antagonist must be used to treat serious respiratory depression in such patient, it should be administered with extreme care and only one-fifth to one-tenth the usual initial dose administered.

Also, oral Meperidine is a big "no no''! as only 50% of ingested drug escapes first pass metabolism and carries very high risk of delirium, seizure and other side effects via its metabolite normeperidine. Moreover, it is significantly less effective by the oral route.

Q: Which pain medicine should be avoided while patient is getting Linezolid (Zyvox)?

Answer: Meperidine

Meperidine along with Linezolid may cause life threatening Serotonin Syndrome. 

References:

1. Das PK, Warkentin DI, Hewko R, Forrest DL.- Serotonin syndrome after concomitant treatment with linezolid and meperidine.- Clin Infect Dis. 2008 Jan 15;46(2):264-5.

2. Elizondo Armendáriz JJ, Pellejero Hernando E, Noceda Urarte MM, Gutiérrez Valencia M. - Probable serotonin syndrome due to linezolid and meperidine interaction, Farm Hosp. 2012 Sep-Oct;36(5):448-9. Epub 2012 Mar 21.

Q: How can be some side effects of Levetiracetam (Keppra) can be curtailed down?

Answer: Addition of Pyridoxine (Vitamin B6) helps in curtailing psychiatric side effects, particularly in children.

Reference: 

Clinical Epilepsy: Pediatrics: Epilepsia 46 (s8): 142–67. 2005

Comparing Normal EEG (Top) 

and 

EEG with generalized seizure (Down) 

Q: Why patients with Citalopram (Celexa) overdose should be observed in hospital or ICU for longer period of time than other SSRIs ?

Answer:  

Patients with citalopram (and escitalopram) overdose should be observed in telemetry bed for at least 13 hours or preferably 24 hours, because of the risk of delayed toxicity, resulting in prolonged QTc interval and consequent cardiac dysrhythmias like torsades de pointes). Another life threatening side effect is occurrence of seizure. 

Patients with other SSRIs overdose are usually OK to discharge after observation for 8-10 hours.

In general, dose for Celexa above 40 mg/day are not recommended because of the risk for QT prolongation.

Reference: 

1. Pacher P, Ungvari Z, Nanasi P, et al. Speculations on difference between tricyclic and selective serotonin reuptake inhibitor antidepressants on their cardiac effects. Is there any? Current Medicinal Chemistry 1999; 6:469-480. 

2. Grundemar L, Wohlfart B, Lagersteedt C, et al. Symptoms and signs of severe citalopram overdose. Lancet 1997; 349: 1602. 

3. Catalano G, Catalano MC, Epstein MA, et al. QTc interval prolongation associated with citalopram overdose: a case report and literature review. Clin Neuropharmacol 2001; May-June: 2-6.

Q: After few minutes of getting first dose of Metronidazole, patient developed tachycardia, fever, shivering, sweating, dilated pupils, twitching, hyper-reflexia, hyperthermia. Patient became confused, agitated and hypertensive. Your concern?

Answer: Serotonin Syndrome from metronidazole

Symptoms of Serotonin syndrom has been reported with metronidazole. Treatment is discontinuation of drug and supportive treatment.

Reference:

Karamanakos, P. N. (2008). "The possibility of serotonin syndrome brought about by the use of metronidazole". Minerva Anestesiologica 74(11): 679.

Q: Why Indomethacin is not advocated any more for the treatment of Dressler's Syndrome?

Answer: 

Indomethacin inhibits new collagen deposition, and thus impairs  the healing process for the infarcted myocardial region. NSAIDs in general are now less advocated in patients with ischemic heart disease. 

Preferred treatment  for Dressler's syndrome is now Colchicine. 

Corticosteroids are still popular with many folks particularly after cardiac surgeries, but the frequency of relapse is high when corticosteroid therapy is discontinued.

Q: What is the difference between between Paroxysmal, Persistent and Permanent Atrial fibrillation?

Answer: 

Type	Time period differentiation
Paroxysmal	recurrent episodes that self-terminate in less than 7 days.
Persistent	recurrent episodes that last more than 7 days
Permanent	an ongoing long-term episode

 Q: How much is usually the loading dose of Amiodarone?

Answer: About 10 grams

An oral loading dose of Amiodarone is around a total of 10 grams, divided over 10 to 14 days. 

Afterwards, a typical maintenance dose of amiodarone is 100 or 200 mg daily.

Interesting article: "Blood-fluid levels in the brain"

"17 cases reviewed prospectively over a period of 4 months highlight then varied appearance of blood–fluid levels in intracranial cystic lesions of different aetiologies; a finding which has not featured significantly in the medical literature. Four types of intracranial cysts demonstrating blood–fluid levels have been categorised according to the nature of the pathology, i.e. primary neoplasms of the brain, metastatic deposits to the brain in cases of extraneural malignancies, lesions of vascular aetiology and intraparenchymal bleeds secondary to trauma......"

Link here: http://bjr.birjournals.org/content/80/954/488.full.pdf+html

Reference: 

Blood-fluid levels in the brain - BJR June 1, 2007 vol. 80no. 954 488-498  

Q: 38 year old female is admitted via ED for unilateral acute nephrolithiasis. Patient is admitted to ICU because of spiking fever, severe dehydration and azotemia. Renal ultrasound was performed in ED. Radiologist calls you to report "a fluid-fluid level" in renal pelvis. What does it mean? 

Answer:  Pyonephrosis 

"a fluid-fluid level" means urine on top of purulent debris. Ultrasound is a much better indicator in identifying pyonephrosis than CT imaging, which is usually performed without contrast in such situations due to severe dehydration and worsening azotemia. Needless to say, antibiotics are required.

Reference:

Jeffrey RB, Laing FC, Wing VW, Hoddick W. Sensitivity of sonography in pyonephrosis: a reevaluation.AJR Am J Roentgenol. Jan 1985;144(1):71-3.

Q: Ethylene glycol intoxication causes Hypocalcemia or Hypercalcemia? (Choose one)

Answer:  Hypocalcemia

Ethylene glycol toxicity (anti freeze) causes hypocalcemia and usually starts occurring around 12 to 36 hours after ingestion. Ethylene glycol metabolized to oxalate and binds to calcium to form Calcium Oxalate crystals.

One of the clue almost always given in Critical Care Board exams is presence of envelope shaped Calcium Oxalate crystals in urine, though presence of it signifies pretty advance stage of toxicity.

Q: What is the the last resort treatment in severe refractory ethanol intoxication?

Answer:  Hemodialysis

Hemodialysis very effectively get rid of ethanol from the blood but it is reserved for severe cases where neurological or hemodynamic situation may become life threatening.

In most cases of ethanol toxicity, supportive treatment is enough to ride off the intoxication phase with IV fluid, IV thiamine, preventing hypoglycemia, preventing electrolyte imbalance, transient use of vasopressors and maintaining normothermia.

Q: What is the ratio of lipase to amylase in Acute alcoholic pancreatitis?

Answer:

In acute alcoholic pancreatitis, the lipase level is usually about 2.5 to 3 times that of amylase. It is a good indication of alcohol as a cause of pancreatitis proved otherwise.