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Health Report:

Age of Transfused Blood & Risk of Complications after Surgery

Obesity, Blood Pressure & Heart Size in Children



"A critical weekly review of important new research findings for health-conscious readers..."


By, Robert A. Wascher, MD, FACS


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Last Updated: 3/23/2008


The information in this column is intended for informational purposes only, and does not constitute medical advice or recommendations by the author.  Please consult with your physician before making any lifestyle or medication changes, or if you have any other concerns regarding your health.


AGE OF TRANSFUSED BLOOD & COMPLICATIONS AFTER SURGERY

Everyday, thousands of people undergoing surgery will require transfusions with lifesaving blood stored in hospital blood banks.  Because of the very small risk of passing infections along to patients with blood transfusions, and because some studies have suggested that blood transfusions might depress immune function, doctors try to reserve blood transfusions only for those patients at greatest risk of complications, including death, from severe anemia.  However, it has long been known that blood, which can be thought of as a living liquid human tissue, deteriorates while being stored, even under refrigerated conditions.  Although fresh blood can be stored for up to 42 days under optimal conditions, the levels of natural substances in red blood cells necessary for proper function begin to decline within few hours after collection from a donor.  At the same time, the living cells within the donated blood continue to churn out metabolic waste substances that can have an adverse effect on very sick patients receiving large volume blood transfusions.

Because individual hospitals can never precisely predict how many blood transfusions will be required from one day to the next, blood banks need to keep a small surplus of blood products on hands at all times.  Since these products are highly perishable, and can only be stored for a limited time before being discarded, most blood banks release their older stocks of blood for transfusion first, much as your neighborhood grocery store places the oldest containers of milk at the front of the shelf.  Older blood, in addition to containing higher levels of potentially toxic metabolites, simply does not take up and unload life-sustaining oxygen as efficiently and as quickly as fresh blood does.  Additionally, the red blood cells contained in older bags of blood are more fragile, and are more easily ruptured (also referred to as hemolysis), further reducing the available number of blood cells available following transfusion (the breakdown products of ruptured red blood cells can also be toxic to the liver and kidneys in patients with abnormal liver and kidney function).  A new research study, just published in the New England Journal of Medicine, has cast further, important, light on this topic.

In this study, nearly 3,000 patients undergoing open-heart surgery were evaluated after being transfused with almost 9,000 units of blood that had been stored for 14 days or less.  The complications and death rates for this group of patients were then compared to a similar group of almost 11,000 open-heart surgery patients who had received “older” blood, which had been collected and stored for more than 14 days.  On average, blood given to the first group of patients was about 11 days old, while the blood transfused into the second group of patients was, on average, about 20 days old (the latter is still well within current blood storage and transfusion guidelines).

When comparing the clinical outcomes for these two otherwise matched groups of patients, the researchers found that the incidence of serious complications and risk of death were significantly higher among the patients receiving the “older” blood.  Specifically, more patients receiving “older” blood remained on a mechanical ventilator for 3 or more days than did the patients receiving “newer” blood (9.7% vs. 5.6%, respectively), and these patients were also more likely to suffer severe infections than the patients who received “newer” blood (4.0% vs. 2.8%, respectively).  Similarly, the risk of kidney failure, which is associated with a high risk of death in critically ill patients, was also significantly higher in patients receiving “older” blood (2.7% vs. 1.6% in patients receiving “newer” blood, respectively).  Finally, and most importantly, the likelihood of death within 1 year of surgery was also significantly higher among the patients receiving “older” blood than was observed in the patients transfused with “newer” blood (11.0% vs. 7.4%, respectively).

This study is a real eye-opener, because it suggests that significant increases in the risk of serious complications and death may be associated with transfusions of even relatively fresh blood, at least in patients undergoing major cardiac surgery.  Whether or not the same degree of adverse effects occur in patients undergoing other types of major surgery was not addressed by this study, although the mechanisms of transfusion-associated illnesses and death are generally thought to be similar irrespective of the type of surgery, and are likely more related to the number and severity of co-existing illness within individual patients. 

The findings of this study should generate further review of the current collection and storage guidelines for blood products, although the typically tight supply of lifesaving blood products at most hospitals means that a significant change in the allowable duration of blood product storage is not likely to change much at all.  At the same time, I expect that hospital blood banks will probably begin taking a closer look at which patients receive transfusions with “older” blood versus “newer” blood.  A prudent approach, based upon the results of this study, would be to develop an algorithm whereby the sickest patients would automatically receive blood that has been stored for less than 14 days, while less seriously ill patients requiring blood transfusions would receive the “older” blood products.

 

OBESITY, BLOOD PRESSURE & HEART SIZE IN CHILDREN

As most of us know, the incidence of obesity among both adults and children in the developed world has been skyrocketing.  Obesity has long been known to be associated with a variety of life-shortening conditions, including high blood pressure, coronary artery disease, congestive heart failure, diabetes, stroke, liver disease and arthritis, among other ailments. 

Chronic high blood pressure (hypertension), by itself, can lead to irreversible damage to the heart, brain, kidneys, retinas and other vital organs.  In the case of the heart, a chronically elevated blood pressure causes the heart to have to work harder, resulting in progressive thickening of the heart’s main pumping chamber, the left ventricle.  Over time, the enlarged and increasingly stiff left ventricle can begin to fail, resulting in the development of congestive heart failure (CHF).  Historically, CHF has been viewed as a disease of the elderly, often occurring after decades of poorly controlled hypertension, or after heart attacks have further damaged the left ventricle.  However, the rising incidence of obesity among children has raised concerns that we may be on the cusp of an epidemic of early-onset obesity-related hypertension and coronary artery disease among young adults.  A timely new research study in the Journal of Pediatrics confirms that such an epidemic may be just around the corner.

In this small study, 44 obese and 22 non-obese children (average age was 8 years) were evaluated for blood pressure and left ventricular size.  Not surprisingly, average blood pressure readings were significantly higher in the obese children.  In fact, 48% of the obese children had documented episodes of hypertension during their daily activities.  Similarly, the obese kids were found to already have enlarged left ventricles, as measured by echocardiography. 

This study reveals the unpleasant truth that pre-pubertal obese children are at markedly increased risk of developing hypertension and left ventricular enlargement (hypertrophy), and should raise alarm bells for any parent with an overweight or obese child.  The presence of confirmed high blood pressure and left ventricular hypertrophy in these kids, and at an average age of only 8 years, almost certainly means that these children will face an extraordinarily high future risk of hypertension-related ailments, and early death, unless they are able to shed their excess weight.

 

 
Disclaimer:  As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity.


Dr. Wascher is an oncologic surgeon, professor of surgery, a widely published author, and the Director of the Division of Surgical Oncology at Newark Beth Israel Medical Center

http://www.sbhcs.com/hospitals/newark_beth_israel/mservices/oncology/surgical.html


Send your feedback to Dr. Wascher at rwascher@doctorwascher.net
 


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Copyright 2008.  Robert A. Wascher, MD, FACS.  All rights reserved.


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