Review for 10.1186/1471-230X-12-179 (2012)

Reviewer's report
Title:Effects of Crystalloids and Colloids on liver and intestine microcirculation
and function in cecal ligation and puncture induced septic rodents
Version: 4Date:9 October 2012
Reviewer: Nicolai Haase
Reviewer's report:
Thank you very much for letting me reassess this paper, which have certainly
improved.
Major compulsory revisions
The paper still contains lots of comparisons between one kind of fluid and sham.
That is, the presented analyses are often “fluid A vs. sham vs. fluid B” and not
“fluid A vs. fluid B”. I think the latter is the appropriate analysis given the aim of
the paper where the authors wish to assess the difference between crystalloids
and colloids.
One example of how this influences the paper:
Results, Macrohemodynamics and blood gas analysis-section: “CI was
significantly increased in the colloid groups (HES and gel) compared to sham.
SVI was significantly improved only in the HES group… when compared to
sham.”
Discussion: “Indeed, the colloid group had a significantly increased cardiac index,
but only the HES solution resulted in an increased SVI.”
I would rephrase the paper as follows (after having seen the details in table 1):
Results/Discussion: “CI was significantly increased in the HES group compared
to CL, but SVI did not differ between the intervention groups.”
Discussion: “Indeed, the HES group had significantly increased cardiac index,
but this was not reflected in an increased SVI.”
or simply “We were not able to demonstrate that colloids provide better
macrohemodynamic resuscitation than crystalloids.” (given table 1).
I think the results section, discussion and figures need to be modified
accordingly.
Figure 2 B:
This figure may still be improved: The “intervention” is various fluid therapies, not
the liver/gut examination which is an outcome evaluation/examination. Please
rephrase your wording.
I think it should be very clear from this figure exactly how the 77 randomised rats
where distributed. E.g. how many rodents were randomised to HES? For the liver
group, it states that 3 HES-rats died and 6 were analysed, so 9 rats were
randomly assigned to HES?? Please include the “9” in the figure and do
accordingly for the other groups.
In a randomised study, one would usually expect a similar number of rats in each
group to begin with. During the intervention period some rats die and you end up
having a varying number of rats for analysis in the groups. In your case it seems
different, as you analyse exactly 6 rats in every group according to the figure. If
this is true, I guess that you randomised additional rats to obtain a group size of
6, but I would question if this is a valid randomisation (e.g. if you have 6 rats in all
groups except one where you have only 5, the last additional rat is just assigned
the last group and not randomised). Please explain and modify the figure
accordingly.
Discussion, last sentence “Therefore we hypothesise… colloids may have an
anti-inflammatory effect in a single and small dose”… This hypothesis is not in
line with the above notion that Ly et al. gave fluid in a 1:4-ratio. I think it should
be omitted.
Minor essential revisions
I think that your conclusion of the main article is very well written, but the
conclusion of the abstract could be improved. Wouldn’t it be possible to mention
HES and your interesting finding that inflammatory marker were raised in the
HES-group.
Tabel 1 Legend: Change “SteroIso” to “Ringer’s acetate”.
Figure 4 legend: Doesn’t explain all symbols in the figure.
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, but I do not feel adequately qualified to assess the
statistics.
Declaration of competing interests:
'I declare that I have no competing interests'