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Letter to the Editor
Is double-blinding possible while administering fluids in
the intensive care unit?
Dear Sir
The publication by Alavi SM
et
al
. highlights a subject with an
ongoing debate, namely the ‘crsytalloid-colloid and colloid–
colloid use following cardiac surgery’.
1
They designed a
randomised, double-blind clinical trial and compared the effects
of three different solutions; 0.9% Ringer’s lactate, 4% gelatin
and 6% hydroxyethyl starch (HES) solution. They concluded that
the HES solution was better in terms of the volume-expanding
effect; lower amounts were required compared to the other two
solutions, and short-term renal functions were better.
We feel that there are several insufficiencies about the
design and contents of the study. We believe that the process
of double-blinding is quite challenging in this study, because
the anesthesiologist or intensivist should be unaware of the
solution administered. The process of double-blinding and how
un-blinding was avoided should be detailed.
The haemodynamic status of the patients was defined using
parameters such as cardiac index, which we think is very
helpful, and also systolic and diastolic blood pressure levels of
the patients. Unfortunately, no information regarding the use
of inotropes intra-operatively and postoperatively was given.
Indications for the use of inotropes were defined, but information
on which type, in what dose and on how many patients they
were used was not mentioned. This particular variable has great
influence on the haemodynamic status of the patient as well the
urinary output.
2
Renal effects were analysed using serum creatinine and BUN
levels, and urinary output. Besides the use of inotropes, the type
of fluid used for cardiopulmonary bypass (CPB) priming, and
the use of diuretics during CPB and in the postoperative period
affect renal functions following cardiac surgery.
3
Moreover, recent developments clearly demonstrated that
the measurement of glomerular filtration rate (GFR) is the best
overall index of renal function rather than measurements of
creatinine and BUN levels alone. Serum creatinine levels do not
increase until the GFR is reduced below 50%.
3
Finally, the reference by Boldt
et
al
. was retracted in 2011.
4
This reference should not be cited in this randomised trial, since
Joachim Boldt, who published many articles on crystalloids and
colloids, particularly in favour of HES solutions, was suspended
for scientific misconduct.
5
We believe that discussion on the use of HES solutions
following cardiac surgery will continue, since there are many
subjects on which consensus has not been reached. Randomised,
double-blind clinical trials are the most valuable studies in the
search for these answers but a good design and well-defined
outcomes are required.
References
1. Alavi SM, Ahmadi BB, Baharestani B, Babaei T. Comparison of the
effects of gelatin, Ringer’s solution and a modern hydroxyl ethyl starch
solution after coronary artery bypass surgery.
Cardiovasc
J
Afr
2012;
23
: 428–431.
2. Hasenfuss G, Teerlink JR. Cardiac inotropes: current agents and future
directions.
Eur Heart
J
2011;
32
: 1838–1845.
3. Abu-Omar Y, Ratnatunga C. Cardiopulmonary bypass and renal injury.
Perfusion
2006;
21
: 209–213.
4.
, Accessed October 14,
2012.
5.
Accessed October 14, 2012.
Department of Cardiovascular Surgery, Medicana
International Ankara Hospital, Ankara, Turkey
AHMET BARIS DURUKAN,
HASAN ALPER GURBUZ,
CEM YORGANCIOGLU
Department of Biology, Hacettepe University Faculty of
Science, Ankara, Turkey
AHMET BARIS DURUKAN,
HASAN ALPER GURBUZ,
Diyarbakir Military Hospital, Department of Cardiovascular
Surgery, Diyarbakir, Turkey
MURAT TAVLASOGLU
