In this episode I’ll:
1. Discuss an article about calcium correction in the ICU
2. Answer the drug information question “What weight should be used to calculate an initial dose of IV immune globulin (IVIG)?”
3. Share a resource about open access medical journals.
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Article
Ionized Calcium in the ICU: Should It Be Measured and Corrected?
Author: Scott Aberegg
Published in CHEST March 2016
Shout out to “Intensivist Anna” for bringing this review article to my attention.
Calcium is vital for many functions, including muscle contraction and coagulation (it is also called clotting factor IV!).
Abnormal calcium levels in ICU patients are a common occurrence, but these levels are not usually due to a disorder in calcium homeostasis.
Routine monitoring and correction of calcium levels is commonplace in many ICUs, including my institution. However routine efforts to correct the serum calcium level only treat the laboratory number; there is no evidence that replacement has an effect on patient morbidity and mortality.
The author of this review article makes the point that routine correction of calcium levels appears to be guided by “The quest for euboxia”. From the blog lifeinthefastlane.com:
Euboxia‘ is the pathophysiological state whereby ‘all boxes on a pathology print-out are in the normal range’ (Reade, 2009). Many people working in critical care settings experience an insatiable desire to achieve this state for their patients. Unfortunately finding a blood test abnormality does not mean that correcting it will make the patient better.
Specific scenarios where monitoring and replacement of calcium are warranted include hypomagnesemia, massive transfusion (due to the citrate anticoagulants in transfused blood which chelate calcium), parathyroid disease, and drug effect (such as from cisplatin).
In addition to calling for a prospective trial to evaluate the usefulness of calcium replacement, the author concluded:
Dramatic curtailment of iCa measurement and calcium administration in several studies was not associated with worsening outcomes. The absence of high-quality data to guide practice allows for a spectrum of approaches to the measurement and treatment of iCa, but these approaches should be guided by basic principles of rational clinical decision-making. Widespread, protocolized measurement and administration with the simple goal of normalizing values in the name of “euboxia” should be discouraged.
Drug information question
Q: What weight should be used to calculate an initial dose of IV immune globulin (IVIG)?
A: It is reasonable to use ideal body weight or adjusted body weight to calculate the initial dose, and make changes based on clinical response.
There are no randomized, prospective trials to provide a conclusive answer to this question. In 11 adult patients studied, the correlation between the dose of IVIG and the change in IgG level was strongest when doses were calculated using IBW versus adjusted or actual body weight.
The American Academy of Allergy Asthma & Immunology posted a discussion on the topic where an expert states:
It is reasonable to start with ideal weight but the dose may have to be adjusted…
This same expert is one of the authors of the UpToDate article on the subject. The article suggests using ideal or adjusted body weight for the initial dose calculation.
There is certainly a lack of high quality evidence in this area. I think it is reasonable to use ideal body weight or adjusted body weight to calculate the initial dose, and make changes based on clinical response.
Resource
The Directory of Open Access Journals (DOAJ) is an online directory that indexes and provides access to high quality, open access, peer-reviewed journals. Over 11,000 journals and 2 million articles are part of this directory.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
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