HIV viral load

Q: HIV-1 RNA quantitation (Viral load for HIV) can be misleading in which of the following conditions

A) acute illness 
B) outbreak of herpes simplex infection 
C) vaccination against influenza 
D) vaccination against tetanus
E)  all of the above 


Answer:  E

As patients with HIV infection get admitted to ICU with acute illness frequently, it is of importance to know that viral RNA levels can be misleading and dramatically falsely elevated during acute illness, herpes simplex infection outbreak, or vaccination against many pathogens like influenza, pneumococcus, and tetanus. It takes about a month for values to return to baseline.



References:

1. Donovan RM, Bush CE, Markowitz NP, et al. Changes in virus load markers during AIDS-associated opportunistic diseases in human immunodeficiency virus-infected persons. J Infect Dis 1996; 174:401. 

2. Mole L, Ripich S, Margolis D, Holodniy M. The impact of active herpes simplex virus infection on human immunodeficiency virus load. J Infect Dis 1997; 176:766. 

3. O'Brien WA, Grovit-Ferbas K, Namazi A, et al. Human immunodeficiency virus-type 1 replication can be increased in peripheral blood of seropositive patients after influenza vaccination. Blood 1995; 86:1082. 

4. Staprans SI, Hamilton BL, Follansbee SE, et al. Activation of virus replication after vaccination of HIV-1-infected individuals. J Exp Med 1995; 182:1727.

Dexamethasone in Meningitis

Q: Dexamethasone is frequently used as an adjuvant therapy in bacterial meningitis. It should be given (select one)

A)  just before or simultaneously with the first dose of antibiotics
B)  after antibiotics are given


Answer: A

Due to not fully understood reasons, if dexamethasone is given after the administration of antibiotics in suspected bacterial meningitis, the likelihood of an unfavorable outcome is much higher. It can be avoided if antibiotics are already administered.


Reference:

van de Beek D, de Gans J, Spanjaard L, et al. Clinical features and prognostic factors in adults with bacterial meningitis. N Engl J Med 2004; 351:1849.

Q: 52 year old male is successfully intubated for impending respiratory failure. Post intubation nurse insert a nasogastric (NG) tube. Follow up x-ray showed NG-tube placed in the post-pyloric area. Your next step (select one)

A) Leave the tube as post-pyloric is ideal place
B) Pull back in gastric area


Answer: B

Post intubation NG tubes are inserted to decompress stomach from possible excessive air from air-mask bagging. There are two other vital reasons for which NG tube should not be allowed to stay in post-pyloric area. (Please note: we are not talking about naso-enteric tube for feeding). Other two reasons are:

1. Leaving NG tube in post-pyloric area may have a potential for electrolyte abnormalities.
2. Relatively, NG tubes are stiffer than enteric tubes used for feeding and may damage the duodenal mucosa.

Q: All of the following are indications to treat suspected digoxin toxicity with digoxin-specific antibody (Fab) fragments except?

A) Life-threatening arrhythmia 
B) Renal dysfunction
C) Neurologic findings
D) Potassium level more than 5 meq/L
E) Elevated liver enzymes (LFT)


Answer: E

Digoxin toxicity in patients on chronic dig therapy is hard to predict, and digoxin level does not correlate with toxicity. Clinical, other laboratory parameters and EKG findings are used to predict 'dig. toxicity'. It can be very life-threatening and usually there is no luxury of time. Benefits usually outweigh risks. All of the above factors can be used to justify the use of digoxin-specific antibody (Fab) fragments, except elevated LFT.


References:

1. Bayer MJ. Recognition and management of digitalis intoxication: implications for emergency medicine. Am J Emerg Med 1991; 9:29. 

2.  Antman EM, Wenger TL, Butler VP Jr, et al. Treatment of 150 cases of life-threatening digitalis intoxication with digoxin-specific Fab antibody fragments. Final report of a multicenter study. Circulation 1990; 81:1744.

Aortoenteric fistula (AEF)

It is said that the first clinical description of Aortoenteric fistula (AEF) given by Sir Astley Cooper in 1829, remained same for almost two centuries - and has not changed.

"A man with a pulsating tumor seized with discharge of blood by stool and who died suddenly about 12 hours later. At autopsy, the jejunum had adhered to the aneurysmal bag and that sac had ulcerated into the intestine."


Reference:

Cooper A. Lectures on the Principles and Practice of Surgery, London 1829. 

Warburg effect? (Type B Lactic Acidosis)

Q: What is Warburg effect? (Type B Lactic Acidosis)


Answer: Warburg effect explains the lactic acidosis in tumor cells. It propose that tumor cells shifts their production of energy predominantly to a high rate of glycolysis followed by lactic acid fermentation in the cytosol, resulting in lactic acidosis in cancer patients. Mutations in oncogenes and tumor suppressor genes are thought to be responsible for the Warburg effect.

Dr. Otto Heinrich Warburg,  a German physiologist and a physician was the sole recipient of the Nobel Prize in Physiology or Medicine in 1931. He was nominated for the award 47 times in his life.


References:

1. Friedenberg AS, Brandoff DE, Schiffman FJ. Type B lactic acidosis as a severe metabolic complication in lymphoma and leukemia: a case series from a single institution and literature review. Medicine (Baltimore) 2007; 86:225. 

2. Sia P, Plumb TJ, Fillaus JA. Type B lactic acidosis associated with multiple myeloma. Am J Kidney Dis 2013; 62:633.

Q: During extubation weaning process, evaluation of abdominal muscles represents (Select one) 

A) Inspiratory muscles
B) Expiratory muscles
C)  Neither
D) A and B


Answer: B

Abdominal muscle reflects expiratory muscle strength. The most objective way is to measure gastric pressure, via gastric balloon catheter following maximal cough efforts. Gastric measurement is not a part of everyday ICU clinical practice but objective of above question is to highlight the role of abdominal muscles in the process of respiration specially to watch for these during weaning/extubation process.


Reference: 

Man WD, Kyroussis D, Fleming TA, et al. Cough gastric pressure and maximum expiratory mouth pressure in humans. Am J Respir Crit Care Med 2003; 168:714.

Happy Thanksgiving

Q: 34 year old female with no significant past medical history is admitted to ICU with ischemic stroke, confirmed by CT and follow up MRI in ED. Enthusiastic medical student did proper physical exam and reports the presence of  'livedo reticularis'. What is the most probable diagnosis?

Answer: Anti-phospholipid (aPL) syndrome

It is called “Sneddon's syndrome”. One of the clinical systemic finding (present in about 20% of the patients)  in patients with aPL and an ischemic cerebrovascular disease is livedo reticularis.
Interestingly, after deep vein thrombosis (DVT) and thrombocytopenia, this is the most common clinical finding in patients with aPL. Other clinical findings may be superficial thrombophlebitis, pulmonary embolism and fetal loss. To note, stroke is found to be more common than transient ischemic attack (TIA) in patients with aPL.


 References:

1. Levine SR, Langer SL, Albers JW, Welch KM. Sneddon's syndrome: an antiphospholipid antibody syndrome? Neurology 1988; 38:798.

2. Francès C, Papo T, Wechsler B, et al. Sneddon syndrome with or without antiphospholipid antibodies. A comparative study in 46 patients. Medicine (Baltimore) 1999; 78:209.

3. Cervera R, Piette JC, Font J, et al. Antiphospholipid syndrome: clinical and immunologic manifestations and patterns of disease expression in a cohort of 1,000 patients. Arthritis Rheum 2002; 46:1019.

Intubation predictors in GBS

Q: All of the following are the predictors of intubation in Guillain-Barre Syndrome (GBS) Except?

A) Liver enzyme increases
B) Inability to stand
C) Inability to lift the elbows
D) Inability to lift the head
E) Serum creatinine increases


Answer: E

In a large prospective study of 722 patients published in 2003, it showed that out of the following six, if four are present - intubation is predicted in 85% of the cases

1. Time of onset to admission less than seven days 
2. Inability to cough 
3. Inability to stand 
4. Inability to lift the elbows 
5. Inability to lift the head 
6. Liver enzyme increases

Objectively, following parameters are very good predictors of impending respiratory failure and advocate elective intubation in GBS patients

1. Forced vital capacity less than 20 mL/kg 
2. Maximum inspiratory pressure less than 30 cmH2O 
3. Maximum expiratory pressure less than 40 cmH2O

References:

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

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

Q: What are the five core recommendations from "choosewisely"- Critical Care Societies Collaborative?


Answer: Choosing Wisely® is an initiative of the ABIM (american Board of Internal Medicine) Foundation. Website is www.choosingwisely.org. 

It works across the board with different societies and entities and to come up with recommendations with four basic objectives

• Supported by evidence 
• Not duplicative of other tests or procedures already received 
• Free from harm 
• Truly necessary

Following five are the basic recommendations  for critical care from Critical Care Societies Collaborative (here)

1.  Don’t continue life support for patients at high risk for death or severely impaired functional recovery without offering patients and their families the alternative of care focused entirely on comfort.

2. Don’t deeply sedate mechanically ventilated patients without a specific indication and without daily attempts to lighten sedation.

3. Don't use parenteral nutrition in adequately nourished critically ill patients within the first seven days of an ICU stay.

4. Don’t transfuse red blood cells in hemodynamically stable, non-bleeding ICU patients with a hemoglobin concentration greater than 7 g/dL. 

5.  Don’t order diagnostic tests at regular intervals (such as every day), but rather in response to specific clinical questions.

Colar sign

Q: 24 year old male is admitted via ED to trauma-ICU after motor vehicle accident. Radiology called to inform you that patient has collar sign. What is collar sign?


Answer: The collar sign is also called the hourglass sign. It is mostly present in diaphragmatic rupture. It is due to a waist-like or collar-like appearance of herniated organs at the level of the diaphragm.

Q: What are the six different types of mechanism for Serotonin Syndrome (SS). Give at least one example of each with  commonly used drug which can precipitate SS?


Answer: Serotonin Syndrome can occur via six ways 

1. Increases serotonin formation -  Tryptophan

2. Increases release of serotonin  - Levodopa

3. Impairs reuptake from the synaptic cleft into the presynaptic neuron - Cocaine, MDMA, Meperidine, Tramadol, selective serotonin reuptake inhibitors (SSRIs)

4. Inhibits serotonin metabolism -  Monoamine oxidase inhibitors e.g linezolid

5. Direct serotonin agonist -  Buspirone,  Fentanyl 

 6. Increases sensitivity of postsynaptic receptor - Lithium

Reference:

Boyer EW, Shannon M. The serotonin syndrome. NEJM 2005; 352:1112.

Q:  69 year old male with previous stroke and dense right sided hemiplegia is admitted to ICU with severe pneumonia requiring intubation and ventilator at 100% FiO2 and high Positive End Expiratory Pressure (PEEP). Complete sedation and neuromuscular blockade is applied. Neuromuscular monitoring is applied with Train of Four (TOF). What one precaution should be taken in this patient?


Answer: Neuromuscular monitoring should not be performed/applied on a paralyzed limb.

In this case TOF should not be measure on right side of the body (with dense hemiplegia). In paralysed muscles, upregulation of acetylcholine receptors occurs after denervation resulting in resistance to nondepolarizing Neuro-Muscular-Blocking-Agents (NMBAs). It gives variable exaggeration of the train-of-four ratio. Consequently, the level of systemic neuromuscular block is usually underestimated if a paretic limb is monitored.


Reference:

1. Moningi S, Durga P, Mantha S, Ramachandra G. Train of four responses in paretic limbs. J Neurosurg Anesthesiol 2009; 21:334. 

Q: All of the following have shown possible beneficial effect in hepatic encephelopathy except?

A) Plasma aromatic amino acids (AAA)
B) Branched chain amino acids (BCAA)
C) Sodium benzoate 
D) Flumazenil 
E) Zinc


Answer: A

Objective of above question is to highlight the role of Amino Acids in hepatic encephelopathy. Evidence is still weak so this should not be used as standard of treatment, but should be kept in mind if situation requires intervention.

It has been suggested that hepatic failure/insufficiency increases the ratio of plasma aromatic amino acids (AAA) to branched-chain amino acids (BCAA), and can be a contributing cause of hepatic encephalopathy. Increasing the BCAA level may reverse this ratio and helps in preventing or improving hepatic encephelopathy. 

 BCAA is also available as an oral supplement, and may helpful as an adjuvant treatment.

So answer to above question is "A" as Aromatic Amino acid (AAA) can be detrimental. All other choices are of benefits in hepatic encephelopathy. 


References:

1. Gluud LL, Dam G, Les I, et al. Branched-chain amino acids for people with hepatic encephalopathy. Cochrane Database Syst Rev 2017; 5:CD001939. 

2.  Naylor CD, O'Rourke K, Detsky AS, Baker JP. Parenteral nutrition with branched-chain amino acids in hepatic encephalopathy. A meta-analysis. Gastroenterology 1989; 97:1033. 

3. Marchesini G, Dioguardi FS, Bianchi GP, et al. Long-term oral branched-chain amino acid treatment in chronic hepatic encephalopathy. A randomized double-blind casein-controlled trial. The Italian Multicenter Study Group. J Hepatol 1990; 11:92. 

4. Horst D, Grace ND, Conn HO, et al. Comparison of dietary protein with an oral, branched chain-enriched amino acid supplement in chronic portal-systemic encephalopathy: a randomized controlled trial. Hepatology 1984; 4:279. 

5. Les I, Doval E, García-Martínez R, et al. Effects of branched-chain amino acids supplementation in patients with cirrhosis and a previous episode of hepatic encephalopathy: a randomized study. Am J Gastroenterol 2011; 106:1081.

Q: About  one-third of patients with Traumatic Brain Injury (TBI) develop possible life threatening coagulopathy. What is the mechanism of action behind it?


Answer: Acute TBI produces systemic release of tissue factor and brain phospholipids into the blood circulation leading to DIC and a consumptive coagulopathy.


Reference:

Zehtabchi S, Soghoian S, Liu Y, et al. The association of coagulopathy and traumatic brain injury in patients with isolated head injury. Resuscitation 2008; 76:52.

Q: All of the following can be probable first signs of Malignant Hyperthermia (MH) except 

A) Hyperthermia 
B) Hypercarbia 
C) Sinus tachycardia 
D) Masseter muscle rigidity 
E) Generalized muscle rigidity


Answer: A

There is a huge misconception that hyperthermia is the first sign of MH. Actually not!

Atleast one study showed that hyperthermia was the first sign in MH in only about 8 percent of the cases, and the sole initial sign in about four  percent of cases. 

All other choices in question can be the initial presenting signs in MH.


Reference:

Larach MG, Gronert GA, Allen GC, et al. Clinical presentation, treatment, and complications of malignant hyperthermia in North America from 1987 to 2006. Anesth Analg 2010; 110:498.

Q: All of the following can cause Type B lactic acidosis except

A) Diabetes mellitus 
B)  Malignancy 
C)  Alcoholism
D)  HIV infection
E)  Short bowel syndrome


Answer:  E

In contrast to type A lactic acidosis, where hypoperfusion is the major cause of lactic acidosis, type B lactic acidosis is mostly due to direct impairment of cellular metabolism.

Short bowel syndrome or other forms of gastrointestinal malabsorption causes type D-lactic acidosis. Large amounts of glucose and starch metabolized  by intestinal bacteria produce D-lactic acid. As humans metabolize D-lactic acid slowly, systemic absorption of the D-isomer of lactic acid leads to high plasma D-lactate and consequently metabolic acidosis.

There is no such thing as type C lactic acidosis.

Bonus pearl: D-lactate levels are not measured by most laboratories so specific orders are needed to run Quantitation of D-lactate level.

Q: Which of the following condition may decrease the the effectiveness of antegrade cardioplegia during Coronary Artery Bypass surgery?

A) Aortic regurgitation
B) Mitral regurgitation
C) ventricular septal defect
D) Mitral stenosis
E) Aortic stenosis


Answer: A

Aortic regurgitation (preexisting) may limit the effectiveness of antegrade delivery of cardioplegia solution into the coronary artery ostia after the ascending aorta is cross-clamped, as much of the cardioplegia solution will regurgitate back into the left ventricle. To avoid complications like left ventricular distension, retrograde cardioplegia through the coronary sinus may be a wise choice.

Q: 23 year old male is admitted to ICU after intentional overdose of carbamazepine. Serum concentrations of carbamazepine (select one)

A) may not peak for over 24 hours
B) may not peak for over 48 hours
C) may not peak for over 72 hours
D) may not peak for over 96 hours
E) Serum carbamazepine cannot be measured, and should be followed clinically.


Answer: D

Serum concentrations may not peak for over 96 hours. It is clinically important to closely follow levels every four to six hours. Though studies have shown correlation varies between concentrations of carbamazepine and clinical signs, but linear trend is expected.


References:

1. Graudins A, Peden G, Dowsett RP. Massive overdose with controlled-release carbamazepine resulting in delayed peak serum concentrations and life-threatening toxicity. Emerg Med (Fremantle) 2002; 14:89.

2. Tibballs J. Acute toxic reaction to carbamazepine: clinical effects and serum concentrations. J Pediatr 1992; 121:295. 

3. Brahmi N, Kouraichi N, Abderrazek H, et al. Clinical experience with carbamazepine overdose: relationship between serum concentration and neurological severity. J Clin Psychopharmacol 2008; 28:241.

Q: What is Howthrone effect?


Answer:  The Hawthorne effect is a type of psychological response in which individuals modify an aspect of their behavior in response to their awareness of being observed.

Clinical significance: Howthorne effect found to be either a confounding or a modifying effect in randomized control trials, and may be responsible for placebo or better cognitive functioning.




References: 

1. McCarney R, Warner J, Iliffe S, van Haselen R, Griffin M, Fisher P; Warner; Iliffe; Van Haselen; Griffin; Fisher (2007). "The Hawthorne Effect: a randomised, controlled trial". BMC Med Res Methodol. 7: 30

2. Wickstrom G, Bendix T. The "Hawthorne effect"--what did the original Hawthorne studies actually show? Scandinavian Journal of Work, Environment & Health. 2000;26:363–367

3. Hrobjartsson A, Gotzsche PC. Is the Placebo Powerless? — An Analysis of Clinical Trials Comparing Placebo with No Treatment. NEJM. 2001;344:1594–1602.

Q: 28 year old female is admitted to ICU with exacerbation of  multiple sclerosis (MS) and optic neuritis. Which of the following anti-seizure drug is found to be neuroprotective in optic neuritis, and has been suggested as an adjuvant treatment in patients with MS who suffered from optic neuritis?

A) Klonopin
B) Levetiracetam
C) Phenytoin
D) Lorazepam
E) Phenobarbital


Answer: C

Inhibition of voltage-gated sodium channels is found to be neuroprotective in preclinical models. Assuming this mechanism of action, sodium-channel inhibition with phenytoin is suggested to be neuroprotective in patient with acute optic neuritis.



Reference:

1. Raftopoulos R, and et al -  Phenytoin for neuroprotection in patients with acute optic neuritis: a randomised, placebo-controlled, phase 2 trial. - Lancet Neurol. 2016 Mar;15(3):259-69

Q: 74 year old male is admitted to ICU with fever, dehydration, headache (specific complaint of tenderness of the scalp to touch), history of weight loss and transient visual loss. Patient also has a history of atrial fibrillation. Astute ICU attending started steroids to cover giant cell arteritis. Surgical team is consulted for temporal artery biopsy. Which of the following medications should be stopped in preparation for temporal artery biopsy?

A) Lopressor
B) Aspirin
C) Warfarin
D) Cardizem CD
E) none of the above


Answer: E

Temporal artery biopsy is a superficial dermatologic procedure done under local anesthesia. Warfarin may increase the risk of bleeding slightly but the risk of adverse events from stopping regular medications far outweigh the small risk of bleeding associated with the biopsy. Using local anesthetic with epinephrine reduces the risk of small vessel oozing. In case of further bleeding, other superficial measures can be applied like direct pressure, sutures, electrocautery, or topical hemostatic agents. 

Q: 26 year old is admitted to ICU with Sickle cell crisis/disease (SCD). Intern on call 'reflexly' ordered three units of blood after hemoglobin level found to be lower than 7 g/dL. Post transfusion Hb is reported 13 g/dL. Now Attending is not happy! and wants to do phlebotomy. What is the target value for Hgb and HgbS, when phlebotomy is implied for SCD?


Answer:

Ideally blood transfusion should be avoided as much as possible in SCD. Hyperviscosity is a significant risk factor after blood transfusion in Sickle cell Disease (SCD). Risk for hyperviscosity goes high with Hgb above 10 g/dL and HgbS more than 50 percent of total Hgb.

Phlebotomy has been employed as one mean to decrease the level of Hgb and HgbS. If phlebotomy is considered to prevent or treat the hyperviscosity in SCD, target is to decrease Hgb below 10 g/dL (and HgbS less than 50 percent of total Hgb).


Note: Above question is an academic exercise. Other means to decrease viscosity in SCD should be considered like exchange blood transfusion, by obtaining proper hematology service consult



Recommended reading:

Schmalzer EA, Lee JO, Brown AK, et al. Viscosity of mixtures of sickle and normal red cells at varying hematocrit levels. Implications for transfusion. Transfusion 1987; 27:228.

Q: Bowel or bladder distention after abdominal surgery cause (select one)

A) Tachycardia
B) Bradycardia


Answer: B

In surgical ICUs, visceral distention of the bowel or bladder after abdominal surgery may result in bradycardia due to vagal reflex.

Q: Which of the following have been proposed (may not have strong evidence) to measure  fluid responsiveness? 

A) Oximetric waveform variation (plethysmographic waveform of the pulse oximeter) 
B) Vena cava assessment
C) Assessment of B-lines on lung ultrasound 
D) Femoral vein diameter 
E) All of the above


Answer:  E

Objective of above question is to introduce various measures which have been used - though may not be clinically evidence based to assess fluid responsiveness in hemodynamically unstable patients. 

If you notice, passive leg raising, point-of-care echocardiography or arterial line based waveform analysed hemodynamic data are not included in the question as they are usually well known.


References:

1. Cannesson M, Desebbe O, Rosamel P, et al. Pleth variability index to monitor the respiratory variations in the pulse oximeter plethysmographic waveform amplitude and predict fluid responsiveness in the operating theatre. Br J Anaesth 2008; 101:200. 

2.  Feissel M, Michard F, Faller JP, Teboul JL. The respiratory variation in inferior vena cava diameter as a guide to fluid therapy. Intensive Care Med 2004; 30:1834. 

3.  Lichtenstein DA, Mezière GA, Lagoueyte JF, et al. A-lines and B-lines: lung ultrasound as a bedside tool for predicting pulmonary artery occlusion pressure in the critically ill. Chest 2009; 136:1014. 

4.  Cho RJ, Williams DR, Leatherman JW. Measurement of Femoral Vein Diameter by Ultrasound to Estimate Central Venous Pressure. Ann Am Thorac Soc 2016; 13:81.

Q: The “crazy-paving” pattern on computed tomography (CT) of the lungs is diagnostic of alveolar proteinosis?

A) True
B) False


Answer: B

Though “crazy-paving” pattern on computed tomography (CT) of the lungs is a 'buzzword" for alveolar proteinosis but it can be seen in other disease processes in infectious, neoplastic, idiopathic, inhalational, and other disorders of the lung. Contrary to popular belief, it is not diagnostic of  alveolar proteinosis. 

Crazy paving is characterized as scattered or diffuse ground-glass attenuation with superimposed interlobular septal thickening and intralobular lines. 

Q: Which of the following anti-seizure drug should be given with caution with intravenous infusion of propofol particularly in the treatment of status epilepticus? 

A) Topiramate 
B) Carbamazepine
C) Fosphenytoin
D) Gabapentin
E) Lacosamide


Answer: A 

Topiramate is a broad spectrum antiseizure medicine, and is available only in oral form. There is no intravenous version available. It has shown to show beneficial effect in refractory status epilepticus when given in a higher dose (up to 1600 mg/day), via nasogastric tube (NGT). But, caution should be exercised when given together with intravenous propofol as Topiramate itself can cause a metabolic acidosis, and may become a synergistic medium for propofol infusion syndrome.


References:

1. Towne AR, Garnett LK, Waterhouse EJ, et al. The use of topiramate in refractory status epilepticus. Neurology 2003; 60:332.

2. Reuber M, Evans J, Bamford JM. Topiramate in drug-resistant complex partial status epilepticus. Eur J Neurol 2002; 9:111.

Q: Fogging or condensation of the endotracheal tube (ETT) is a reliable sign of tracheal intubation?

A) True
B) False

Answer:  False

Fogging or condensation of the ETT is reported up to 83 percent of esophageal intubations, at least per one study - and should NOT be used as a reliable indicator of proper placement of ETT in trachea.


Reference:

Kelly JJ, Eynon CA, Kaplan JL, et al. Use of tube condensation as an indicator of endotracheal tube placement. Ann Emerg Med 1998; 31:575.