Wednesday August 15, 2007
myasthenia gravis - Bedside tip !

Patients with myasthenia gravis (MG) crisis are frequently admitted under ICU care. One important bedside tip to remember is: Iodinated IV contrast is associated with further exacerbation of MG, and should be avoided if possible.


Related previous pearl: "Ice test" - Poor man's test for Myasthenia Gravis


Reference: click to get abstract/article

1. Iodinated contrast agents in myasthenia gravis, Neurology.1987; 37: 1400

Today's ICU Pearl
Tuesday August 14, 2007

CPR on patient with IABP If patient requires CPR who is on Intra-Aortic Baloon Pump (IABP) - do not switch off IABP. Switch from "ECG trigger" to "Pressure trigger". IABP during CPR improves cerebral and cardiac blood flow. With CPR, on "pressure trigger", an arterial pressure tracing should be generated on console/screen and if the console is not recognising the arterial pressure tracing, chest compressions may not be adequate. (If feels uncomfortable regarding IABP during code - just put IABP to 'standby' mode during code).

Related: IABP care protocol - (source: London Health Sciences Centre, Canada)


Further Reading:

P. J Overwalder: Intra Aortic Balloon Pump (IABP) Counterpulsation. The Internet Journal of Thoracic and Cardiovascular Surgery. 1999. Volume 2 Number

Monday August 13, 2007
Ischemia Modified Albumin (IMA)

When we look at the standard coronary disease predictors (Troponin-I & CK-MB) we are looking at values that reflect necrosis. In one small study the use of IMA along with Myoglobin, CK-MB, & Troponin-I increased the sensativity of detecting an ischemic event to 97% with a negative predictive value of 92%. Similar other reports in literature are also posing for this test to be an integral part of cardiac events in future (see references).


Above pearl contributed from:

Ken Davis at Eastern New Mexico University - Roswell (DAVISKE@roswell.enmu.edu)



References: click to get abstract/article

1. Role of "Ischemia Modified Albumin", a new biochemical marker of myocardial ischaemia, in the early diagnosis of acute coronary syndromes - Emerg Med J 2004; 21:29-34
2. Ischemia-Modified Albumin and Myocardial Ischemia - Kalay et al. J Am Coll Cardiol.2007; 49: 2375
3. Utility of admission cardiac troponin and "Ischemia Modified Albumin" measurements for rapid evaluation and rule out of suspected acute myocardial infarction in the emergency department - Emergency Medicine Journal 2006;23:256-261
4. "Ischemia modified albumin": a new biochemical marker of myocardial ischaemia Emerg Med J.2004; 21: 3-4
5. "Ischemia modified albumin" from thedoctorsdoctor.com

Sunday August 12, 2007
icumedicus


This website should be a bookmark for all intensivists.

www.icumedicus.com

Interesting features of site include

• Scoring Systems
• ICU Calculators
• CCM Guidelines
• Core Lectures
• ICU Cases
• ICU Procedures
• Medical Images
• Waveform Analysis
• X-Rays
• EKG Interpretation
• Free Full Text Journals

Saturday August 11, 2007
Blue dye in tube feedings

Although initially thought to be without risk and a reasonable indicator of aspiration, the nutritional support community advises AGAINST putting blue dye into tube feeds. Blue dye was thought to be non-absorbable, non-toxic, and sensitive for aspiration. However, now it is hypothesized that blue dye can be absorbed systemically due to increased intestinal permeability and that it can cause decreased mitochondrial oxygen consumption and mitochondrial toxicity.

ASPEN (American Society of Parenteral and Enteral Nutrition) recommends against the use of blue dye in tube feeds. The reasons include:

● The reliability and validity have not been adequately tested.
● There have been reports of skin and body organ staining.
● No safe amount of dye has been established.

Since blue dye is NOT recommended to routinely detect aspiration, prevention is the best treatment. Prevention may include:

● Adjusting rate of administration based on tolerance, bowel sounds, and residuals.
● Elevating the head of bed 45 degrees or more.
● Pro-motility agents.




References: click to get abstract/article

1. Use of Colored Dyes in Enteral Formulas. REVIEW ARTICLE - Topics in Clinical Nutrition. 21(3):226-233, July/September 2006
2. Systemic absorption of food dye in patients with sepsis. N Engl J Med 2000;343(14):1046-7.
3. Skin discoloration with blue food coloring. Ann Pharmacother 2000;34:868-70.
4. Evidence-based practice for enteral feedins:aspiration prevention strategies, bedside detection, and practice changes. Medsurg Nurs 2000;9(1):27-31.

Friday August 10, 2007
Insulin in TPN

Adding insulin to the TPN bag itself - this is chemically compatible and has been done for years. The debate comes in when we start to discuss how much actually makes it to the patient. Study results have been variable. The amount of insulin adsorbed (i.e. stuck to) the glass bottle, plastic bag, or plastic IV tubing can be as high as 80%. Some factors affecting this adsorption include type of container, solution, administration set, previous exposure of tubing to insulin, etc. The binding appears to happen within the first 30-60 minutes. Some in vitro studies have been conducted to assess the effect of "priming" the line with a dilute insulin solution. Priming the tubing with a dilute solution or running through and wasting the first aliquot of the insulin-containing solution increases delivery of insulin from 38% to 85% at 2 hours. Once the priming is done, the amount of insulin delivered remains pretty constant.

Other options - although costly and controversial, adding albumin in small concentrations may help deliver higher amount of insulin by decreasing the amount of insulin available to bind to the container and/or tubing. Adding 0.3 gram/100ml seems to decrease adsorption. Flushing the tubing with the insulin-containing solution two hours before administration seems to saturate the binding sites and minimizes further adsorption. Giving the insulin as a separate IV infusion is another delivery option but adsorption should be considered in this setup as well.

Thursday August 9, 2007
Choice of IVF in Thyroid storm

In Thyroid storm, solutions that contain dextrose (some experts recommend even 10% dextrose solution) should be given as IVF. The hepatic glycogen reserve is usually depleted in thyroid storm and dextrose will help replenishing it and to cope with continuously high metabolic demand. Naturally, electrolyte monitoring is recommended with dextrose solution infusion.


Bonus Pearl: Aspirin is contraindicated for control of pyrexia in thyroid storm and tylenol is the prefered agent.


Related pearl: Iodide in Thyroid Storm


Reference:

1. Thyroid Storm: Recognizing the signs and symptoms of this life-threatening complication. AJN, American Journal of Nursing. 102(5):33-35, May 2002.

Wednesday August 8, 2007
Vasoconstrictor extravasation

Antidote for vasoconstrictor extravasation in skin and tissues (dopamine, epinephrine, or norepinephrine) is PHENTOLAMINE.

Infiltrate 5-15 mg of PHENTOLAMINE in 10 ml of normal saline into the area of extravasation as soon as possible. Treatment may be applied and effective up to 12 hours post extravasation of vasoconstrictor. Keep yourself ready for fluid bolus post treatment.

Mechanism of action: Phentolamine is a nonspecific alpha-adrenergic blocking agent which inhibits vasoconstriction and allow improved blood circulation through the affected area.


References: Click to get abstract or article

1. Drug Monographs - Phentolamine - lhsc.on.ca
2. Treating Extravasation Injuries - extravasation.org
3. The use of phentolamine in the prevention of dopamine-induced tissue extravasation - J Crit Care 1998 Mar;13(1):13-20

Tuesday August 7, 2007
Fentanyl induced chest wall (thoracic) rigidity - FITR

Fentanyl is one of the most commonly used analgesic in ICUs. One of the relatively unknow but common side effect of Fentanyl is chest wall rigidity which was first reported about 25 years ago and may happen with low dose. Chest wall rigidity itself can lead to respiratory distress causing hypercapnia, and hypoxemia leading to bradycardia. Moreover, it may also make intubation difficult as often chest wall rigidity is associated with laryngospasm. Treatment is reversal with Naloxone. If respiratory failure does not resolve, airway should be secured followed with sedation and neuromuscular blockade till fentanyl wears off. The mechanism of action is not known but suspected to be neuraxis dopamine antagonism.


Fentanyl induced thoracic rigidity is relatively more common in neonates.




References: click to get abstract/article

1. Rigidity and hypercarbia associated with high dose fentanyl induction of anesthesia (Letter). Anesth Analg 1981; 60: 362–3

2. Opioid-induced rigidity after intravenous fentanyl - Obstetrics & Gynecology 1997;89:822-824

Monday August 6, 2007
Regarding false positive Digoxin level

Many common clinical conditions may lead to false positive elevations of plasma digoxin and erroneous medical management. Actually, many experts don't believe in checking digoxin level unless there is any clinical manifestation due to many artifactual factors such as poor assay quality, incorrect timing or technique of drawing blood samples. Atleast, in following 3 conditions, there is an increase of endogenous digoxin-like substances in plasma which may lead to false positive result with total error upto 0.6 - 1.8 ng/mL.

• chronic renal failure
• hepatobiliary disease
• in the third trimester of pregnancy

Also atleast 3 commonly used drugs (like steroid derivative drugs) may cross react with the digoxin radioimmunoassay and give false postive values.

• spironolactone
• methylprednisolone
• Tobramycin

Note: New born neonates can have very high false postive digoxin level upto 4 ng/mL due to increased levels of endogenous digoxin-like substances.

References: click to get abstract/article

1. Digoxin-like substance in the serum of uremic patients before and after hemodialysis - Cardiovascular Drugs and Therapy, Volume 2, Number 6 / January, 1989
2. Cross-Reactivity of TDX and OPUS Immunoassay Systems for Serum Digoxin Determination. Therapeutic Drug Monitoring. 19(6):657-662, December 1997.
3. Falsely elevated digoxin levels: another look - Ther Drug Monit. 1989 Sep;11(5):572-3

Sunday August 5, 2007
Sedatives and sexual dreams - a legal liability?

In 1847, after a year of ether anesthesia introduction, a dentist was convicted to 6 years of jail for sexually assaulting two girls under the influence of anaesthesia. There are well documented cases where physicians and dentists have lost their licenses for similar allegation. Anaesthetics particularly propofol (widely use in ICU) has been reported to be associated with vivid dreams and sexual fantasies though a fairly good study failed to show any association. Recently, Dr. Robert Strickland's report in this regard at the American Society of Anesthesiologists meeting has been widely reported in media and is worth reading. Click on reference # 2.


References: Click to get abstract or article

1. Dreams, images and emotions associated with propofol anaesthesia -Anaesthesia, Volume 52, Number 8, July 1997, pp. 750-755(6)
2. Anesthesia can give rise to sex illusion - ARIZONA DAILY STAR - 06.21.2005

Saturday August 4, 2007
Hypomagnesemia and IV Magnesium (Mg) infusion

Hypomagnesemia has been reported in upto 60% of ICU patients and sometimes can be clinically very significant like in recovery phase of DKA (diabetic ketoacidosis). Symptoms of severe hypomagnesemia (less than 1 mEq/L) include respiratory failure, hyperactive deep-tendon reflexes, muscular fibrillations, mental status changes, tetany, seizures, positive Chvostek and Trousseau signs. EKG manifestations are prolong PR interval, widened QRS complex, ST depression, altered T waves and last but not the least is loss of voltage. About 33% of serum magnesium is protein-bound but unfortunately wide-spread test for free or active (ionized) magnesium is not available. It is a common practice to write IV Mg orders in grams or mls.

1 gram of IV Mg contains 8.12 meq of Mg and
1 meq of Mg provides 12 mg of elemental Mg.

One ml MgSO4 50% Solution = 4 meq Magnesium
One ml MgSO4 10% Solution = 8 meq Magnesium

Rapid IV administration can induce life threatening cardiac dysrhythmias, hypotension, flushing, sweating, sensation of warmth and hypocalcemia. In non-emergent cases, general rule of thumb is to infuse 1 gram per 1 hour. In risky situations, like impending arrhythmia, 2 grams of IV Magnesium sulfate may be given over 20 minutes. In extremely emergent cases 2 grams (16 mEq) of IV MgSO4 may be administered over 5 minutes and actually may be given as IV push if there is no permission of time.

In Preeclampsia, load IV 4-6 grams of MgSO4 in 100 ml of D5W over 20-30 minutes and maintenance is 2-3 grams/hour with close monitoring of target level (goal of 4-7 mEq/L) and clinical manifestations like decrease deep tendon reflexes. It is not a bad idea to keep IV calcium at bedside during massive IV magnesium infusion as in preeclampsia.

IV calcium is an antidote for magnesium overdose.

In kidney dysfunction, IV magnesium dose should be reduced by about 50%.

Friday August 3, 2007
step-up oxygen saturation and VSD


Case: 61 year old male admitted with Angina. Cardiac cath. showed 3 vessel disease. Cardiac Bypass surgery planned for next morning. Patient admitted back to CCU with protocolized post cardiac cath orders. Around 12 midnight, patient suddenly became hypotensive. Arriving at bedside you noticed tall v waves on pulmonary artery catheter tracings. You suspect flail Mitral valve (Mitral regurgitation - MR) with possible ruptured Chordae tendinae. Cardiologist is also concerned about ventricular septal defect (VSD). Unfortunately, STAT Echo is not available at 12 MN. What would be the best way to differentiate between MR and VSD ?



VSD is very difficult to diagnose from MR on clinical grounds. VSD can be differentiated from MR by demonstrating a step-up in oxygen saturation in the right ventricle. (By collecting blood from CVP, RV and PA/distal ports of PA catheter).

If oxygen saturation level in right ventricle is more than 5% from right atrium or 8% from pulmonary artery (due left-to-right shunt across the ventricular septum), it is diagnostic of VSD. In this era of technology, echocardiography is preferable, if available, due to its non-invasive and good diagnostic value.



Reference: click to get abstract/article

Hemodynamic complications of ventricular septal rupture after acute myocardial infarction - Catheterization and Cardiovascular Interventions, Volume 60, Issue 4 , Pages 509 - 514, 2003

Thursday August 2, 2007

Case: 24 year old male admitted with left thigh cellulitis and abcess. I and D was performed and cefazolin (ancef) was initiated. Patient did not respond to cefazolin and antibiotic was changed to vancomycin after availability of sensitivity from micro lab. Patient showed marked improvement over next 3 days except patient complaint of new rash on his body which you attributed to "Red man syndrome" and wrote an order to infuse vancomycin slowly and with increase dilution. Next day, as you reached hospital, you were informed by outgoing intensivist that patient deteriorated overnight and required intubation. You were baffled and as you examine the patient, you find extensive dermal exfoliation along with axillary and inguinal lymphadenopathy. On lab, LDH and liver enzymes were markedly elevated and kidney funtion deteriorated from normal to anuria. CBC showed eosinophilia.



Vancomycin-induced Stevens-Johnson syndrome


Stevens-Johnson syndrome is an acute mucocutaneous process characterized by severe exfoliative dermatitis and mucosal involvement of the gastrointestinal tract and conjunctiva. Pathogenesis is unclear, but an immunological mechanism, probably cell-mediated, has been suggested. Clinical diagnosis of Stevens-Johnson syndrome is based on the presence of "target" or "iris" lesions involving the skin and erosive lesions of two or more mucosal surfaces. Associated findings include extensive dermal exfoliation, nephritis, lymphadenopathy, hepatitis, and multiple serologic abnormalities. Vancomycin, a glycopeptide antibiotic, has case reports in literature produceing immunologically mediated adverse reactions such as interstitial nephritis, linear IgA bullous dermatosis, exfoliative erythroderma, necrotizing cutaneous vasculitis and toxic epidermal necrolysis. The treatment consists of cessation of vancomycin and administration of antihistamine and/or steroid.




References: click to get abstract/article

1.Vancomycin-induced Stevens-Johnson syndrome Allergy Asthma Proc. 1996 Mar-Apr;17(2):75-8.

2.Stevens-Johnson-type reaction with vancomycin treatment. - Ann Pharmacother. 1992 Dec;26(12):1520-1

3 Uncommon Vancomycin-Induced Side Effects - Brazilian Journal of Infectious Diseases - 2002;6(4):196-200

Wednesday August 1, 2007


Q; 72 year old female with no significant past medical history has been admitted from ER to ICU with progressive mental status change over last 3 days. Only significant finding in workup is Na+ of 123 mEq/liter. The only pertinent history is start of a new anti-depressant medication about 2 weeks ago. Per son, there is no sign of drug over-dose ?

A; Anti-depressants' associated hyponatremia.One of the significant but less know side effect of anti-depressants, mostly SSRIs is hyponatremia. Exact mechansism is unknown but it causes SIADH (Syndrome of Inappropriate Antidiuretic Hormone). It has also been reported with 'atypical' anti-depressents' (venlafaxine, trazodone, maprotiline, nefazodone, bupropion) as well as with tricyclic antidepressants (TCAs) and monamine oxidase inhibitors (MAOIs).When prescribing antidepressants particularly to elderly patients, consideration of hyponatremia should be kept in mind. Patients who develop mental status change need prompt assessment of electrolytes' status. Patients already at risk of the SIADH (such as cancer) should be prescribed anti-depressent with caution and close followup.


Related previous pearl: ANTIDEPRESSANTS' AND SEROTONIN SYNDROME


References: click to get abstract/artice

1. Hyponatremia in the psychiatric population: a review of diagnostic and management strategies. Psychiatr Ann 2003; 33:318–325

2. Hyponatremia secondary to antidepressants. Psychiatr Ann 2003; 33:333–339

3. Hyponatremia in elderly psychiatric patients treated with selective serotonin reuptake inhibitors and venlafaxine: a retrospective controlled study in an inpatient unit. Int J Geriatr Psychiatry 2002; 17:231–237

4. Hyponatremia with venlafaxine. Ann Pharmacother 1998; 32:49–50

5. Severe symptomatic hyponatremia during citalopram therapy - a case report - BMC Nephrology 2004, 5:2