Saturday October 31, 2009

Your Diagnosis?

Answer: Atrial fibrillation and complete heart block

• Fibrillary waves of atrial fibrillation and no P waves
• Regular ventricular rhythm
• The wider the QRS of the ventricular escape rhythm the less reliable the escape mechanism
• AF with complete heart block can be easily missed and is an indication for a permanent pacemaker

Friday October 30, 2009
Reglan


Q: Reglan (Metoclopramide) is a very commonly use drug in ICU. Does it get removed via CVVHD ?


A: NO !

(Reglan) Metoclopramide is excreted principally through the kidneys. In patients with creatinine clearance below 40 mL/min, dose should be curtailed at approximately one-half the recommended dosage. Dialysis removes relatively little Metoclopramide. Similarly, continuous ambulatory peritoneal dialysis does not remove significant amounts of drug.

Cumulative doses with prolong ang higher dose may manifest as tardive dyskinesia, a syndrome consisting of potentially irreversible, involuntary, dyskinetic movements. Elderly patients are likely to develop the syndrome. Anticholinergic or antiparkinson drugs or antihistamines with anticholinergic properties may be helpful in controlling the extrapyramidal reactions. Symptoms are self-limiting and usually disappear within 24 hours.




recommended article

1. Drug Dosing in Critically Ill Patients with Renal Failure: A Pharmacokinetic Approach - Journal of Intensive Care Medicine, Volume 15 Issue 6 Page 273-313, November/December 2000

Thursday October 29, 2009


Q: What could be the supporting finding on lab in (Transfusion-related acute lung injury (TRALI)?


Answer: Laboratory findings may include unexpected haemoconcentration and a sudden fall in serum albumin. As in other causes of acute alveolar capillary leak, the pulmonary exudate in TRALI has a high albumin content. Peripheral blood neutropenia has been reported but neutrophilia is more common.



Reference:

The pathology of transfusion-related acute lung injury. Am J Clin Pathol 1999; 112: 216–21

Wednesday October 28, 2009
Reference Standard Change for Heparin

Source: www.fda.gov/Safety/medwatch

Effective October 1, 2009, there is a new reference standard and test method to determine the potency of heparin, as well as, impurities in heparin. This change will result in a 10% reduction in potency of heparin marketed in the United States.

Clinicians should take caution with monitoring and dosing, as more heparin may be needed to achieve and maintain desired level of anticoagulation in patients.

Product with the new “USP unit” potency definition will be available on or after October 8, 2009. Most manufacturers will place an “N” next to the lot number to indicate that the vial is of the new potency.

Tuesday October 27, 2009
Sulfonylurea overdose

Anti-diabetic pills overdose remained one of the leading cause of drug overdose worldwide. Among anti-diabetic pills sulfonylureas are the most dangerous and hard to correct. Overdose of metformin rarely causes clinically evident hypoglycemia (It has its own danger of cardiovascular collapse and renal failure, due to severe lactic acidosis).

Unfortunately very few clinicians use the real antidote for sulfonylurea which is Octreotide (Sandostatin) in resistant hypoglycemia. Infusion of glucose to achieve euglycemia in the early phase is an appropriate treatment but there is some literature available which argues that prolong infusion of dextrose in sulfonylurea overdose may make hypoglycemia longer and worse by stimulating insulin release. The dose for Octreotide is 50 mcg SC every 8 hours with adjustment of dose according to blood glucose level. Octreotide is a somatostatin analogue, which activates G-protein K channel and hyperpolarization of the beta cell results in inhibition of Ca influx and insulin release. Another antidote for sulfonylurea overdose beside octreotide is Diazoxide.

Exact mechanism is unknow but probably it increases blood glucose by inhibiting pancreatic insulin release. It is found to be effective within 60 minutes of administration. The usual dose is 5 mg/kg/day intravenously and should be divided every 8 hours. Dose can be increased if needed but still its experience in comparison to octreotide is limited.



References: click to get abstracts/articles

1. Octreotide for sulfonylurea-induced hypoglycemia following overdose - The Annals of Pharmacotherapy: Vol. 36, No. 11, pp. 1727-1732

2. Clinical spectrum of sulfonylurea overdose and experience with diazoxide therapy - Archives of Internal Medicine Vol. 151 No. 9, September 1, 1991

Monday October 26, 2009
Going back to basics


Q: Explain Ejection fraction (Ef)?

Answer: By definition, the volume of blood within a ventricle immediately before a contraction is known as the end-diastolic volume. Similarly, the volume of blood left in a ventricle at the end of contraction is end-systolic volume. The difference between end-diastolic and end-systolic volumes is the stroke volume, the volume of blood ejected with each beat. Ejection fraction (Ef) is the fraction of the end-diastolic volume that is ejected with each beat; that is, it is stroke volume (SV) divided by end-diastolic volume (EDV):

Ef = SV/EDV
OR
Ef = EDV-ESV/EDV

In a healthy 70-kg (154-lb) man, the SV is approximately 70 ml (left ventricular ESV is 50 ml and the left ventricular EDV is 120 ml) giving an ejection fraction of 70/120, or 0.58 (58%)

Sunday October 25, 2009


Q: What is the basis of treatment for Torsade de Pointes?

Answer: The basis of treatment for Torsade de Pointe is sppression of early afterdepolarizations.

Magnesium is the drug of choice for suppressing EADs and terminating the arrhythmia. This is achieved by decreasing the influx of calcium, thus lowering the amplitude of EADs. Magnesium is effective even in patients with normal magnesium levels.

Some authorities recommend supplemental potassium to increase the potassium concentration to high normal, which increases the efflux of potassium from myocardial cells, thus causing rapid repolarization.