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Although such reactions are not true allergic events, they raise the issue of safety with dextran solutions. Severe dextran-induced anaphylactoid reactions have been well recognized since the 1970s. Fortunately, dextran 1 (Promit) usually prevents such reactions. When it is administered immediately before dextran 40 or 70, dextran 1 acts as a hapten inhibitor that binds dextran-specific antibodies and blocks larger molecules of dextran 40 or 70 from forming immune complexes. Hapten inhibition with dextran 1 has been found to reduce the incidence of severe dextran-induced anaphylactoid reactions from 1 in 2000 to 1 in 70,000.2,3
The Food and Drug Administration's Blood Products Advisory Committee recently recommended adding information about the prophylactic benefit of dextran 1 to the package insert for dextran products to increase awareness among providers.4
Craig E. Zinderman, M.D., M.P.H.
Robert Wise, M.D., M.P.H.
Laurence Landow, M.D.
Food and Drug Administration
Rockville, MD 20852
zinderman{at}cber.fda.gov
References
Ashish Goel, M.D.
Molly M. Thabah, M.D.
All India Institute of Medical Sciences
New Delhi 110029, India
ashgoe{at}yahoo.com
References
Goel and Thabah refer to previous work on fluid resuscitation from our unit, as a result of which the present study was designed. These early studies did not provide definitive results, and in fact, the second study suggested possible benefits from colloid use. Their letter also highlights an important issue regarding the changes in blood pressure that occur as the dengue shock syndrome worsens. With increasing cardiovascular compromise, the diastolic pressure rises toward the systolic and the pulse pressure narrows. Finally, there is decompensation, and both pressures disappear abruptly. The higher diastolic pressure in group 2 is thus a marker of the increased severity in this group.
Great care was taken to ensure blinding. Three bottles of the assigned fluid were supplied for each patient and were sealed inside identical opaque containers with only the (identical) injection port visible, into which the staff could insert a cloudy plastic infusion set without breaking the seal. An independent research assistant removed all containers from the ward, still sealed, within 24 hours after the enrollment of patients. Close inspection of infusion sets did reveal minor differences, but since each patient had only a single line, we think it is unlikely that busy staff had time for the investigation required to compromise blinding.
All patients who presented with the dengue shock syndrome but were not enrolled in the study for various reasons (as discussed in our article) were treated in the same way as the 512 patients in the formal study, apart from the initial blinded resuscitation. For all the patients who were not enrolled in the study, there were identical observations and outcome evaluations recorded in similar study files, and all patients in this group recovered fully. The only death among all 641 children admitted with the dengue shock syndrome during the trial period occurred in a study patient. Meticulous clinical management combined with appropriate use of intravenous fluids can greatly reduce mortality from the dengue shock syndrome.
Bridget A. Wills, M.R.C.P.
Oxford University Clinical Research Unit
Ho Chi Minh City, Vietnam
bridgetw{at}hcm.vnn.vn
Nguyen M. Dung, M.D.
Hospital for Tropical Diseases
Ho Chi Minh City, Vietnam
Jeremy J. Farrar, F.R.C.P.
Oxford University Clinical Research Unit
Ho Chi Minh City, Vietnam
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