Thursday, December 12, 2019

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.

Wednesday, December 11, 2019

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.

Tuesday, December 10, 2019

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

Monday, December 9, 2019

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.

Sunday, December 8, 2019

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.

Saturday, December 7, 2019

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.

Friday, December 6, 2019

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. 

Thursday, December 5, 2019

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.

Wednesday, December 4, 2019

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.

Tuesday, December 3, 2019

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.

Monday, December 2, 2019

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.

Sunday, December 1, 2019

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.

Saturday, November 30, 2019

Maze

Q: What are the three principal goals of surgical intervention in atrial fibrillation?

Answer: 
  • Creation of conduction block to disrupt all micro- and macro-reentrant circuits. 
  • Reestablishment or maintenance of electrical atrioventricular synchrony. 
  • Restoration of atrial mechanical function in order to improve diastolic filling.
The objective of the above pearl is to concisely put the surgical solution to atrial fibrillation. First two goals are well known but interestingly third and the most vital goal frequently goes unnoticed. 

#cardiology
#surgical-critical-care


Reference: 

Ferguson TB Jr, Cox JL. Surgery for atrial fibrillation. In: Cardiac Electrophysiology: From Cell to Bedside, 2nd ed, Zipes DP, Jalife J (Eds), Saunders, Philadelphia 1995. p.1567.

Friday, November 29, 2019

Axillary A line

Q: While inserting axillary arterial line, it should be ideally placed

A) as high as possible within the axilla
B) at low as possible within the axilla


Answer: A

The axillary arterial line should be inserted as high into the apex of the axilla as possible by palpation, or ideally as visualized by ultrasound. The axillary fossa can be exposed well by abduction and external rotation of the arm. This is due to the fact that as at a higher level the axillary artery receives good collateral flow through thyrocervical trunk and subscapular artery. This reduces risk of ischemia.


#procedures



Reference:


Htet N, Vaughn J, Adigopula S, Hennessey E, Mihm F. Needle-guided ultrasound technique for axillary artery catheter placement in critically ill patients: A case series and technique description. J Crit Care. 2017 Oct;41:194-197. doi: 10.1016/j.jcrc.2017.05.026. Epub 2017 May 25. 

Thursday, November 28, 2019

pilot with SOB

Q: 44 year old air-force pilot is brought to ED after his flight with chest pain, and dyspnea. Patient describes these symptoms progressively getting worse after each air flight. What is your diagnosis?


Answer: Acceleration atelectasis

Acceleration atelectasis can occur in pilots who are subject to very high, vertical accelerative forces between 5G and 9G. half of the pulmonary airways are distorted and closed at 5G due to gravitational forces. This leads to atelectasis which gets worse by superimposed breathing of high fractional concentration of oxygen. Progressively these pilots may have decrease in vital capacity.

Slide presentation @ Acceleration Atelectasis: New risks from an old friend ( by Ross Pollock
and Alec Stevenson) - (courtesy of QINETIQ PROPRIETARY)  

url: http://www.safeeurope.co.uk/media/7901/n-dr-ross-pollock_acceleration-atelectasis-new-risks-from-an-old-friend.pdf

#pulmonary


Reference:

Tacker WA Jr, Balldin UI, Burton RR, et al. Induction and prevention of acceleration atelectasis. Aviat Space Environ Med 1987; 58:69.

Wednesday, November 27, 2019

Diabetes and AAA

Q: Diabetes ____________ the risk for Abdominal Aortic Aneurysms (AAA)? (select one)

A) increases
B) decreases


Answer: B

Although diabetes is well known to increase the risk for any vascular disease but surprisingly it decreases the risk for AAA. The most popular hypothesis regarding this protection is mediated through effects on aortic mural neoangiogenesis, intraluminal thrombus formation, inflammation, glycation, extracellular matrix remodelling, and vascular smooth muscle homeostasis. Similar effect has been reported for Thoracic-AA but pathways may be different.

#surgical-critical-care


Reference:

Juliette Raffort, Fabien Lareyre, Marc Clément, Réda Hassen-Khodja, Giulia Chinetti, Ziad Mallat. Diabetes and aortic aneurysm: current state of the art Cardiovascular Research, Volume 114, Issue 13, 01 November 2018, Pages 1702–1713, https://doi.org/10.1093/cvr/cvy174

Tuesday, November 26, 2019

etomidate

Q: Etomidate also has partial analgesic effect. 

A) True 
B) False


Answer: B

Etomidate has absolutely no analgesic effect. The objective of the above question is to emphasize that  an opioid analgesic, such as fentanyl, should be considered few minutes prior to intubation to blunt the noxious stimulation of the upper airway due to laryngoscopy and insertion of endotracheal tube.



#procedure
#pharmacology


Reference:

Schneider, RE, Caro, DA. Pretreatment agents. In: Manual of Emergency Airway Management, Walls, RM (Eds), Lippincott Williams & Wilkins, Philadelphia 2004. p.185.

Monday, November 25, 2019

Friction rub in stomach

Q: During auscultation of an acute abdomen, the sound of friction rub on the left side of the abdomen raises the possibility of which disease process?


Answer: Splenic infarct

Friction rub in splenic infarct is due to the sliding of peritoneal layers over the infarcted splenic area. This is not an exclusive sign and should be considered with other clinical and laboratory clues pointing towards splenic pathology.



#physical-exam

#surgical-critical-care
#gastroenterology


Reference:


1. Lawrence YR, Pokroy R, Berlowitz D, Aharoni D, Hain D, Breuer GS. Splenic infarction: an update on William Osler's observations. Isr Med Assoc J. 2010 Jun;12(6):362-5.

Sunday, November 24, 2019

Contact isolation

Q: Transmission via droplets occurs within how many feet of an infected patient, and requires droplet isolation? 

 

Answer: 3-6 feet 

Many patients particularly chronically sick patients may be colonized with organisms that may disseminate via droplet. These include Neisseria meningitidis, Bordetella pertussis, influenza, parainfluenza, adenovirus, Haemophilus influenzae type b, Mycoplasma pneumoniae, rubella, Respiratory syncytial virus (RSV), and others. These particles are usually more than 5 microns, remain suspended in the air for a limited time, and risk of transmission is highest within 3-6 feet. 


This need to understand that there is a difference between droplet isolation and airborne precautions. The doors of patient rooms may remain open in droplet isolations. Airborne Precautions are required for organisms/particles that remain suspended in the air, travel on air currents and can be inhaled by others. These include Mycobacterium tuberculosis (TB), varicella (chickenpox) and measles viruses. Ideally, an infectious disease service should be consulted to determine the proper level of isolation required.


#infectious-diseases



Reference:


1. United States Center for Disease Control and Prevention. 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings. https://www.cdc.gov/infectioncontrol/pdf/guidelines/isolation-guidelines-H.pdf (Accessed on November 01, 2019).

Saturday, November 23, 2019

Extubation

Q: Is the following statement  true:

"If patients were rested back on the ventilator for an hour before extubation after the completion of a spontaneous breathing trial (SBT), it may decrease the rate of reintubation at 48 hours".

A) Yes
B) No


Answer: Yes

One relative recent trial of 18 institutions from Spain comprising of 243 patients randomized to the control group and 227 to the rest group, showed that the above strategy decreased the reintubation at 48 hours from 14% to 5%. The multivariable regression model demonstrated that the variables independently associated were rest, APACHE II, and days of ventilation before SBT. Interestingly, age, reason for admission, and the type and duration of SBT were not associated with decrease in reintubation rate. 


Although, the study was well conducted but still requires reproducibility of results.


#Ventilation

#pulmonary


Reference:


1. Fernandez MM, González-Castro A, Magret M, et al. Reconnection to mechanical ventilation for 1 h after a successful spontaneous breathing trial reduces reintubation in critically ill patients: a multicenter randomized controlled trial. Intensive Care Med 2017; 43:1660.

Friday, November 22, 2019

BB and delirium

Q: How Beta-blockers directly contribute to delirium?



Answer: By decreasing Melatonin

Although delirium is usually multi-factorial and very hard to pin-point on one exclusive culprit. Various cardiac drugs including beta-blockers, digoxin, diuretics, and anti-arrhythmia agents can be a direct or indirect contributor.  The objective of this question is to bring to discussion the interesting mechanism by which B-blockers induce delirium. Beta-blockers reduce the level of melatonin and may cause a direct contribution to delirium. This reduction in melatonin is due to a specific decrease in production of melatonin via inhibition of brain adrenergic beta1-receptors as evidenced by decreased urinary secretion of melatonin. Other mechanisms have also been proposed like BBs effect on serotonin (5-HT) receptors. 


#neurology

#pharmacology


 References:

1. Brismar K, Mogensen L, Wetterberg L: Depressed melatonin secretion in patients with nightmares due to beta-adrenoceptor blocking drugs. Acta Med Scand 1987; 221:155–158 

2. Fisher AA, Davis M, Jeffery I: Acute delirium induced by metoprolol. Cardiovasc Drugs Ther 2002; 16:161–165

3. Dimsale JE, Newton RP, Joist T. Neuropsychological side effects of beta-blockers. Arch Intern Med1989;149:514–25.

Thursday, November 21, 2019

sleep aids in ICU

Q: Why trazodone is preferred over quetiapine as a sleep aid in ICU?

Answer:

There is no objective verified data on the basis of biochemical studies to prefer one over the other but based on patient-reported and nursing-observed sleep outcomes trazodone is preferred over quetiapine. 


Trazodone is a serotonin modulator. It causes a good amount of sedation but is better tolerated than benzodiazepines as it does not cause physiologic tolerance or dependence. It should be used with caution in cardiac patients due to its risk of causing arrhythmias.

#pharmacology
#sleep-in-ICU


References:


1. Doroudgar S, Chou TI, Yu J, et al. Evaluation of trazodone and quetiapine for insomnia: an observational study in psychiatric inpatients. Prim Care Companion CNS Disord 2013; 15.


2. Lenhart SE, Buysse DJ. Treatment of insomnia in hospitalized patients. Ann Pharmacother 2001; 35:1449.

Wednesday, November 20, 2019

hypothermia and hematocrit

Q: What's the relationship between hypothermia and hematocrit?

Answer:  Hypothermia can affect a wide range of laboratory finding and most of the abnormalities in lab are proportional to the degree of hypothermia. With each 1°C drop in temperature the hematocrit increases by 2 percent. 

Clinical significance: A low normal hematocrit is considered abnormal in severe hypothermia.


#hypothermia
#hematology


Reference:

Mallet ML. Pathophysiology of accidental hypothermia. QJM 2002; 95:775.

Tuesday, November 19, 2019

Air embolism and volume status

Q: Which of the following increases the risk of air embolism during central venous catheter (CVC) insertion or removal? (select one)

A) Hypovolemia 
B) Hypervolemia 


 Answer: A

Any factor which reduces the central venous pressure below atmospheric pressure places the patient at particular risk for entraining air rapidly. Two such factors during insertion or removal are 


  • hypovolemia during insertion, and 
  • upright position during removal 

Some other risk factors for air embolism are broken CVC, detached connections (which accounts for 60 to 90 percent of episodes), and deep inspiration during insertion or removal.

#procedures



References:


King MB, Harmon KR. Unusual forms of pulmonary embolism. Clin Chest Med 1994; 15:561.

Kashuk JL, Penn I. Air embolism after central venous catheterization. Surg Gynecol Obstet 1984; 159:249.

Monday, November 18, 2019

stages of empyema

Q: There are how many stages of pleural empyema? 

Answer: 3

There are three stages of pleural (or any) empyema 

  • stage 1 is an exudative phase 
  • stage 2 is when frank pus is visible 
  • stage 3 is the organization phase 
Clinical relevance: As empyema progressed towards late stage 2 and 3, the surgical consultation should be obtained.

#pulmonary
#surgical-critical-care


References:


1. Wozniak CJ, Paull DE, Moezzi JE, et al. Choice of first intervention is related to outcomes in the management of empyema. Ann Thorac Surg 2009; 87:1525. 


2. Ahmed AE, Yacoub TE. Empyema thoracis. Clin Med Insights Circ Respir Pulm Med 2010; 4:1.

Sunday, November 17, 2019

WE and temperature

Q: Unreactive pupil in Wernicke's Encephalopathy (WE) is found to be associated with? (select one)

A) Hypothermia
B) Hyperthermia


Answer:

The objective of the above question is to address initial management in WE. On initial exam in patients suspecting of having WE, if found to have unreactive pupil should be checked for the need for normothermia. Hypothermia may exacerbate the morbidity and mortality in WE.  This is due to dysfunction in the thermoregulatory functions of the hypothalamus. Unreactive pupil and hypothermia are also found to be associated with autonomic dysfunction and hypotension. This calls for rewarming of the patient.


#toxicology

#neurology


References:


1. Harper CG, Giles M, Finlay-Jones R. Clinical signs in the Wernicke-Korsakoff complex: a retrospective analysis of 131 cases diagnosed at necropsy. J Neurol Neurosurg Psychiatry 1986; 49:341.

 
2. Philip G, Smith JF. Hypothermia and Wernicke's encephalopathy. Lancet 1973; 2:122.

Saturday, November 16, 2019

NGT

Q: What is the ideal location for a nasogastric tube (NGT) to decompress the stomach?

Answer:  gastric fundus

NGT for the purpose of decompressing the stomach should be targetted to positioned in the gastric fundus. It decreases the risk of getting NGT adherent to the walls of the stomach and so the risk of injury to the gastric mucosa. Also, it provides a wider area of suction around the NGT with better symptomatic relief to the patient.  Less utilized but an effective technique to confirm its placement is to use the bedside ultrasound.


#procedures




References: 


Zatelli M, Vezzali N. 4-Point ultrasonography to confirm the correct position of the nasogastric tube in 114 critically ill patients. J Ultrasound. 2016;20(1):53–58. doi:10.1007/s40477-016-0219-0

Friday, November 15, 2019

Corrosive esophagitis

Q: Which one is more prone to cause immediate esophageal injury and esophageal perforation? (select one) 

 A) Acid-induced injury 
 B) Alkali-induced injury 


 Answer: B

Contrary to the popular belief alkali based solutions are more prone to cause penetrating injury. Extensive transmural damage can happen within seconds resulting in esophageal perforation and deadly mediastinitis. It is called liquefactive necrosis. If a patient survives the immediate ordeal, it follows by vascular thrombosis, extensive sloughing, and ulceration, development of granulation tissue and fibrosis. re-epithelialization occurs with stricture formation. 


 Acid-based solutions are less prone to cause esophageal damage as they cause unbearable pain upon contact with the oropharynx, and stimulated gagging.


#toxicology



References:


1. Zargar SA, Kochhar R, Nagi B, et al. Ingestion of strong corrosive alkalis: spectrum of injury to upper gastrointestinal tract and natural history. Am J Gastroenterol 1992; 87:337.
 


Thursday, November 14, 2019

Asynchrony

Q: One of the major reasons for 'asynchrony' between a patient and a mechanical ventilator is? (select one)

A) Increasing tidal volume (TV) with an increased flow rate
B) Increasing tidal volume (TV) without an increased flow rate


Answer: B

One common mistake done by novices is to increase only the tidal volume in an attempt to increase minute ventilation to adjust for respiratory acidosis. This results in prolonged inspiratory time manifested as asynchrony. Ideally, the inspiratory flow rate should also be increased whenever the tidal volume is increased.


#ventilators

#pulmonary


References:


1. Vieillard-Baron A, Prin S, Augarde R, et al. Increasing respiratory rate to improve CO2 clearance during mechanical ventilation is not a panacea in acute respiratory failure. Crit Care Med 2002; 30:1407.


2. Tobin MJ, Jubran A, Laghi F. Patient-ventilator interaction. Am J Respir Crit Care Med 2001; 163:1059.


3. Manning HL, Molinary EJ, Leiter JC. Effect of inspiratory flow rate on respiratory sensation and pattern of breathing. Am J Respir Crit Care Med 1995; 151:751.

Wednesday, November 13, 2019

coagulation profile blood draw

Q: While drawing blood for the coagulation profile, what should be the ratio of citrate solution to whole blood in the tube to have an accurate result?

Answer: 1:9

The objective of the above question is to bring to light the errors which can occur at multiple levels and may give wrong results and render patients to undue transfusions. 

In USA the recommended tube for coagulation profile is with the 'blue top'. It is filled with 3.2 percent sodium citrate solution. To get the ratio of 1:9 between the citrate solution and the whole blood, the tube must be filled within 90 percent of the full collection volume. If the tube is not properly filled, it will disequilibrate the 1:9 ratio leading to an inaccurate results. Above said, in patients with polycythemia some of the citrate should be removed due to a reduced plasma volume, to attain the 1:9 ratio. 

Tubes should be gently inverted a few times to mix the citrate solution with the blood. Shaking of the tube will cause the hemolysis. 

 Also, the tube should be tested in a timely manner as factors V, VIII and protein S can be degraded quickly. And, tubes should not be frozen prior to separation of plasma from cells.

#hematology


References:

1. Adcock DM, Kressin DC, Marlar RA. Minimum specimen volume requirements for routine coagulation testing: dependence on citrate concentration. Am J Clin Pathol 1998; 109:595. 


2. Chuang J, Sadler MA, Witt DM. Impact of evacuated collection tube fill volume and mixing on routine coagulation testing using 2.5-ml (pediatric) tubes. Chest 2004; 126:1262. 

3. Zürcher M, Sulzer I, Barizzi G, et al. Stability of coagulation assays performed in plasma from citrated whole blood transported at ambient temperature. Thromb Haemost 2008; 99:416.

Tuesday, November 12, 2019

TRALI

Q: Patients who develop transfusion-related acute lung injury (TRALI) with pre-existent acute respiratory distress syndrome (ARDS) have? (select one) 

 A) TRALI type I 
 B) TRALI type II


Answer: B

The objective of the above question is to bring to attention the new modification to the pre-existent classification of TRALI. This modification to/and the previous standard classification was developed by the National Heart, Lung, and Blood Institute (NHLBI) working group and a Canadian Consensus Conference (CCC).

  • If a patient develops TRALI without any concomitant risk factor for ARDS, it is called type-I 
  • If a patient develops TRALI with any concomitant risk factor for ARDS or even have signs of existing ARDS is called type-II
Due to copyright reasons, we can't reproduce full tables here but all previous and new tables can be accessed via references below.

#pulmonary
#hematology


References:

1. Kleinman S, Caulfield T, Chan P, et al. Toward an understanding of transfusion-related acute lung injury: statement of a consensus panel. Transfusion 2004; 44:1774. 

2. Toy P, Popovsky MA, Abraham E, et al. Transfusion-related acute lung injury: definition and review. Crit Care Med 2005; 33:721. 


3. Toy P, Kleinman SH, Looney MR. Proposed revised nomenclature for transfusion-related acute lung injury. Transfusion 2017; 57:709. Vlaar APJ, 


4. Toy P, Fung M, et al. A consensus redefinition of transfusion-related acute lung injury. Transfusion 2019; 59:2465.

Monday, November 11, 2019

Resp failure in GBS

Q: All of the following are good indicators of respiratory failure in Guillain-Barre Syndrome (GBS) except?

A) Forced vital capacity (FVC) of less than 20 mL/kg 
B) Maximum inspiratory pressure (MIP) less than 20 cmH2O 
C) Inability to stand 
D) Inability to lift the elbows 
E) Increased Liver enzymes


Answer: B

The objective of the above question is to bring into light the two less known predictors of impending respiratory failure. Clinicians often confused numbers between forced vital capacity (FVC), maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP). 

The rule is 20-30-40 


  • FVC less than 20 mL/kg 
  • MIP less than 30 cmH2O 
  • MEP less than 40 cmH2O 

 (Tip to remember: You are always Forced to Inspire before Expire) 

 Paying attention to increased liver enzymes may also help. Other easy to notice clinical signs are the inability to cough, stand, lift the elbows or the head.


#neurology

#pulmonary


References:


1. Lawn ND, Fletcher DD, Henderson RD, et al. Anticipating mechanical ventilation in Guillain-Barré syndrome. Arch Neurol 2001; 58:893. 


2. Sharshar T, Chevret S, Bourdain F, et al. Early predictors of mechanical ventilation in Guillain-Barré syndrome. Crit Care Med 2003; 31:278.

Sunday, November 10, 2019

Uhthoff phenomenon

Q: 32 year old female with a previous history of multiple sclerosis (MS) is admitted to ICU with a flare of her symptoms. Neurology service diagnosed her with the Uhthoff phenomenon. What is Uhthoff phenomenon?


Answer: Transient flare-up of symptoms of MS due to increase in body temperature

Uhthoff phenomenon, named after a german ophthalmologist Wilhelm Uhthoff, is a transient (less than 24 hours) worsening of neurological function among MS patients in response to increases in core body temperature. This is distinct from the true relapse or exacerbation of MS. It does not require 
corticosteroid pulse therapy or plasma exchange therapy. It has been described in other neuropathies too. The mechanism of action is the temperature-sensitive conduction blockade of partially demyelinated axons in the demyelinated plaques. Precipitating factors include perimenstrual period, exercise, fever, hot bath, psychological stress, a hot meal, and smoking.


Treatment is rest and cooler environment.



#neurology 



References:


1. Opara JA, Brola W, Wylegala AA, Wylegala E. Uhthoff`s phenomenon 125 years later - what do we know today? J Med Life. 2016 Jan-Mar;9(1):101-105. 


2. Perkin GD, Rose FC. Uhthoff's syndrome. Br J Ophthalmol. 1976 Jan;60(1):60-3. 


3. Frohman TC, Davis SL, Beh S, Greenberg BM, Remington G, Frohman EM. Uhthoff's phenomena in MS--clinical features and pathophysiology. Nat Rev Neurol. 2013 Sep;9(9):535-40. 


4. van Diemen HA, van Dongen MM, Dammers JW, Polman CH. Increased visual impairment after exercise (Uhthoff's phenomenon) in multiple sclerosis: therapeutic possibilities. Eur. Neurol. 1992;32(4):231-4. 

Saturday, November 9, 2019

Drugs which exacerbate the symptoms of anaphylaxis by nonimmunologic mast cell activation

Q:  All of the following can exacerbate the symptoms of anaphylaxis by causing nonimmunologic mast cell activation except?

A) ethanol
B) nonsteroidal anti-inflammatory drugs (NSAIDs)
C) opiates
D) ACE inhibitors


Answer: D

There are several groups of drugs that can make symptoms of anaphylaxis worse but they all have a different mechanism of actions (MOAs). 


Ethanol, NSAIDs, and opiates (choices A, B, and C) exacerbate anaphylaxis by causing nonimmunologic mast cell activation. ACE inhibitors block the effect of angiotensin, a compensatory response, and block the degradation of kinins, which are active in the production of symptoms and signs (choice D).  


Beta-blockers can potentially make anaphylaxis difficult to treat, and Alpha-blockers may decrease the effects of endogenous or exogenous epinephrine.


#anaphylaxis

#pharmacology


References:


1. Simons FE. Anaphylaxis. J Allergy Clin Immunol 2010; 125:S161. 


2. Mueller UR. Cardiovascular disease and anaphylaxis. Curr Opin Allergy Clin Immunol 2007; 7:337.

Friday, November 8, 2019

Risk of rejection in heart transplant

Q: All of the following tends to increase the risk of acute rejection after heart transplant except?

A) Older recipient 

B) Female recipient 
C) Female donor 
D) Afro-American recipient 
E) Degree of HLA mismatches


Answer:  A

Contrary to popular belief younger people between age 30 and 60 tend to have more risk of rejection. This is probably due to their robust immune system. As body see the transplanted heart as a foreign object and tends to react more vigorously. 


#transplantation

#cardiology


References:


1. Kubo SH, Naftel DC, Mills RM Jr, et al. Risk factors for late recurrent rejection after heart transplantation: a multiinstitutional, multivariable analysis. Cardiac Transplant Research Database Group. J Heart Lung Transplant 1995; 14:409. 


2. Kobashigawa JA, Kirklin JK, Naftel DC, et al. Pretransplantation risk factors for acute rejection after heart transplantation: a multiinstitutional study. The Transplant Cardiologists Research Database Group. J Heart Lung Transplant 1993; 12:355. 

3. Jarcho J, Naftel DC, Shroyer TW, et al. Influence of HLA mismatch on rejection after heart transplantation: a multiinstitutional study. The Cardiac Transplant Research Database Group. J Heart Lung Transplant 1994; 13:583.

Thursday, November 7, 2019

Intubation in trauma

Q: Patients from trauma scene should be intubated without the anterior portion of the cervical collar removed? (select one)

A) True
B) False


Answer: B

The anterior portion of the cervical collar should be temporarily removed for intubation in patients who arrive from a trauma scene with a complete cervical collar in place. Tracheal intubations performed with the complete cervical collar in place are associated with greater spinal subluxation. Said that despite the anterior portion of the cervical collar is temporarily removed, manual in-line stabilization should be maintained particularly during bag-mask ventilation (BMV).


#trauma

#procedure


Reference:


Austin N, Krishnamoorthy V, Dagal A. Airway management in cervical spine injury. Int J Crit Illn Inj Sci. 2014;4(1):50–56. doi:10.4103/2229-5151.128013

Wednesday, November 6, 2019

pneumothorax and leucocytosis

Q: In spontaneous pneumothorax (PTX), what is the characteristic of leucocytosis?


Answer: There is less likelihood of left shift

Although there is no confirmatory lab test to confirm pneumothorax, sizeable PTX always leads to some degree of leucocytosis but characteristically left shift is usually absent.


#pulmonary



More readings:

1. Richard W Light, Clinical presentation and diagnosis of pneumothorax. uptodate.com, last updated: Apr 15, 2019. 


2. T. I. Akcam, O. Kavurmaci, A. G. Ergonul et al., “Analysis of the patients with simultaneous bilateral spontaneous pneumothorax,” The Clinical Respiratory Journal, vol. 12, no. 3, pp. 1207–1211, 2018.


3. O. Bintcliffe and N. Maskell, “Spontaneous pneumothorax,” BMJ, vol. 348, Article ID 2928, 2014

Tuesday, November 5, 2019

Organ donation

Q: Use of thyroid hormone therapy during the management of the deceased organ donor has shown association with increased procurement of all of the following organs except

A) heart
B) lungs
C) kidneys
D) pancreas
E) liver


Answer: E

Thyroid hormone therapy during the management of the deceased organ donor is found to have improved cardiac output and hemodynamic stability. In a huge retrospective analysis of data of 63,593 donors, it was concluded that the thyroid hormone was associated with increased procurement of hearts, lungs, kidneys, pancreases, and intestines, but not livers.


#organ-donation



Reference:


Novitzky D, Mi Z, Sun Q, et al. Thyroid hormone therapy in the management of 63,593 brain-dead organ donors: a retrospective analysis. Transplantation 2014; 98:1119.

Monday, November 4, 2019

Frisén Scale

Q: Frisén Scale is used to grade which disease?



Answer:  Papilledema

Frisén Scale is used to grade the severity of papilledema with six stage, from stage 0 to  Stage 5. 

  • Stage 0 is a normal optic disc. 
  • Stage 1 papilledema is a C-shaped halo of disc edema with preservation of the temporal disc. 
  • Stage 2 papilledema is a circumferential halo of edema on the optic disc.  
  • Stage 3 papilledema is elevation of the optic disc with partial obscuration of one of more segments of the blood vessels at the disc margin. 
  • Stage 4 papilledema is characterized by almost complete obscuration of major blood vessels on the optic disc. 
  • Stage 5 papilledema is partial or total obscuration of all blood vessels on the surface of the optic disc.

Each stage is further categorized into AB, ABC or ABCD level

#ophthalmology



Reference:


Frisén, L. Swelling of the optic nerve head: a staging scheme. J Neurol Neurosurg Psychiatry 1982; 45:13. Graphic 73887 Version 1.0

Sunday, November 3, 2019

ischemic colitis

Q: Which areas of the colon are more prone to ischemia due to hypo-perfusion?



Answer: Splenic flexure and rectosigmoid junction

The blood supply of large intestine and rectum comes from the superior mesenteric artery, inferior mesenteric artery, and internal iliac arteries. Fortunately, there is an extensive collateral circulation to protect the bowel from compromised perfusion, except in the "watershed" areas i.e.,  splenic flexure and rectosigmoid junction.


#surgical-critical-care

#gastroenterology



References:


Brandt LJ, Feuerstadt P, Blaszka MC. Anatomic patterns, patient characteristics, and clinical outcomes in ischemic colitis: a study of 313 cases supported by histology. Am J Gastroenterol 2010; 105:2245. 


Greenwald DA, Brandt LJ, Reinus JF. Ischemic bowel disease in the elderly. Gastroenterol Clin North Am 2001; 30:445.

Saturday, November 2, 2019

Mollaret's meningitis

Q: What is Mollaret's meningitis? 

Answer: Mollaret's meningitis is a form of recurrent benign lymphocytic meningitis (RBLM). It is defined as greater than three episodes of fever and meningismus lasting two to five days, followed by spontaneous resolution. It may cause transient seizures, hallucinations, diplopia, cranial nerve palsies, or change in mental illness. The most common cause is HSV-2 virus and may present without any genital lesions at the time of presentation. The diagnosis is made by PCR testing for virus in the CSF. Treatment is valacyclovir, 500 mg twice daily for 12 months. Other causes besides HSV-2 have also been described for Mollaret's meningitis.

#neurology

#infectious-diseases


References:


1. Shalabi M, Whitley RJ. Recurrent benign lymphocytic meningitis. Clin Infect Dis 2006; 43:1194. 


2. Schlesinger Y, Tebas P, Gaudreault-Keener M, et al. Herpes simplex virus type 2 meningitis in the absence of genital lesions: improved recognition with use of the polymerase chain reaction. Clin Infect Dis 1995; 20:842. 

3. Aurelius E, Franzen-Röhl E, Glimåker M, et al. Long-term valacyclovir suppressive treatment after herpes simplex virus type 2 meningitis: a double-blind, randomized controlled trial. Clin Infect Dis 2012; 54:1304. 

Friday, November 1, 2019

Vaccines in immunocompromised patients

Q: Immunosuppressed patients should not receive which of the following vaccines while in the ICU or on discharge?

A) Pneumococcus (PCV13 and PPSV23)
B) Seasonal influenza 
C) Hepatitis A & B 
D) Tetanus, diphtheria, pertussis (Tdap) 
E) Measles, mumps, rubella (MMR)


Answer: E

Out of all of the above, only MMR is the live attenuated vaccine. All live attenuated vaccines should be either avoided or given with extreme caution to the immunocompromised patients. Similar such vaccines are influenza nasal spray, rotavirus, varicella vaccine, oral typhoid. yellow fever and some formulations of the Japanese encephalitis vaccine. 


#infectious-diseases



References:


1. Grohskopf LA, Sokolow LZ, Broder KR, et al. Prevention and control of seasonal influenza with vaccines: Recommendations of the Advisory Committee on Immunization Practices – United States, 2018-19 influenza season. MMWR Recomm Rep 2018; 67:1. 


2. Singh JA, Saag KG, Bridges SL Jr, et al. 2015 American College of Rheumatology guideline for the treatment of rheumatoid ahritis. Arthritis Rheumatol 2016; 68:1. 


3. van Assen S, Agmon-Levin N, Elkayam O, et al. EULAR recommendations for vaccination in adult patients with autoimmune inflammatory rheumatic diseases. Ann Rheum Dis 2011; 70:414. 


4. O'Neill SG, Isenberg DA. Immunizing patients with systemic lupus erythematosus: a review of effectiveness and safety. Lupus 2006; 15:778.

Thursday, October 31, 2019

CBF and PaCO2

Q: Cerebral blood flow (CBF) decreases by what percentage per drop of each mm Hg in the arterial partial pressure of carbon dioxide (PaCO2)?



Answer:  2%

The objective of the above question is to highlight the relationship between respiratory alkalosis (R-Al) and cerebral blood flow. Hypocapnia in R-Al causes cerebral artery vasoconstriction, resulting in reduced cerebral blood flow. 


 CBF decreases by 2% for every 1 mm Hg drop in PaCO2.


#pulmonary

#neurology
#acid-base


Recommended reads:


1. Yoon S, Zuccarello M, Rapoport RM. pCO(2) and pH regulation of cerebral blood flow. Front Physiol. 2012;3:365. Published 2012 Sep 14. doi:10.3389/fphys.2012.00365 


2. Ito H, Kanno I, Ibaraki M, Hatazawa J, Miura S.Changes in human cerebral blood flow and cerebral blood volume during hypercapnia and hypocapnia measured by positron emission tomography. J Cereb Blood Flow Metab. 2003 Jun;23(6):665-70.

Wednesday, October 30, 2019

ETT exchange

Q: Video laryngoscopy is recommended for the Endo-tracheal tube (ETT) exchange? 

A) True
B) False



Answer: A

Exchange of ETT is a serious business as it can very quickly degenerate into a life-threatening situation with loss of airway leading to cardiac arrest. It should be carried out by an experienced provider or at least with an immediate backup of an expert. Usually, exchange of ETT is carried out in similar fashion as the placement of a new ETT. The same level of vigilance, preparation and medications should be used. It is usually of help to visualize the vocal cord prior to exchange of ETT with direct blade or video laryngoscope. 


At least one recent prospective study of 328 patients in whom the vocal cords were not easily visualized using direct blade laryngoscopy, comparing with historical controls, video laryngoscopy reduced the number of attempts for ETT exchange from 92 to 68 percent in first attempt, and lesser complications such as hypoxemia, esophageal intubation, bradycardia, and need for back up.

#procedure


Reference:

Mort TC, Braffett BH. Conventional Versus Video Laryngoscopy for Tracheal Tube Exchange: Glottic Visualization, Success Rates, Complications, and Rescue Alternatives in the High-Risk Difficult Airway Patient. Anesth Analg 2015; 121:440.

Tuesday, October 29, 2019

Fentanyl

Q; Fentanyl is? (select one) 

A) lipophilic 
B) hydrophilic


Answer: A

The objective of the above question is to emphasize the fact that though fentanyl is short-acting, due to its highly lipophilic state it rapidly gets distributed to highly perfused tissues i.e., brain, heart, kidney, and gastrointestinal tract followed by slower redistribution to muscle and fat tissues. This accumulated storage results in prolonged sedation and respiratory depression even when fentanyl is discontinued.


#pharmacology

#sedation
#analgesia


References:


1. Choi, Leena PhD; Ferrell, Benjamin A. MD; Vasilevskis, Eduard E. MD, MPH; Pandharipande, Pratik P. MD, MSCI; Heltsley, Rebecca PhD; Ely, E. Wesley MD, MPH; Stein, C. Michael MB, ChB; Girard, Timothy D. MD, MSCI - Population Pharmacokinetics of Fentanyl in the Critically Ill - Critical Care Medicine: January 2016 - Volume 44 - Issue 1 - p 64–72 

2. Kuip EJ, Zandvliet ML, Koolen SL, Mathijssen RH, van der Rijt CC. A review of factors explaining variability in fentanyl pharmacokinetics; focus on implications for cancer patients. Br J Clin Pharmacol. 2017;83(2):294–313. doi:10.1111/bcp.13129


3.Gourlay GK, Murphy TM, Plummer JL, Kowalski SR, Cherry DA, Cousins MJ: Pharmacokinetics of fentanyl in lumbar and cervical CSF following lumbar epidural and intravenous administration. Pain 1989; 38:253-9

Monday, October 28, 2019

Vitamin A intoxication

Q: 53 year old male with End-Stage renal Disease (ESRD) starts taking over the counter (OTC) multi-vitamin supplements. Patient presented with severe headache and is admitted to ICU after neurology service diagnosed him with pseudotumor cerebri. Patient was also found to have  Vitamin A intoxication. Patient is also likely to have? (select one)

A) Hypocalcemia
B) Hypercalcemia


Answer: B

Patients with ESRD should be prescribed or be cautioned against using OTC supplements. Vitamin A intoxication is a potential concern in these patients. Hypervitaminosis A may cause nausea, headache, fatigue, irritability, anorexia, hepatomegaly, and pseudotumor cerebri. It also causes hypercalcaemia due to the effect of vitamin A on bone, most likely an osteolytic effect.

#toxicology

#nephrology
#neurology


References:


1. Hammoud D, El Haddad B, Abdallah J. Hypercalcaemia secondary to hypervitaminosis a in a patient with chronic renal failure. West Indian Med J. 2014;63(1):105–108. doi:10.7727/wimj.2011.171 


2.  Lippe B, Hensen L, Mendoza G, Finerman M, Welch M. Chronic vitamin A intoxication. A multisystem disease that could reach epidemic proportions. Am J Dis Child. 1981;135:634–636.


3. Farrington K, Miller P, Varghese Z, Baillod RA, Moorhead JF. Vitamin A toxicity and hypercalcaemia in chronic renal failure. Br Med J (Clin Res Ed) 1981;282:1999–2002.