Review for 10.1186/1471-230X-14-18 (2014)

Reviewer's report
Title:Effects of paracentesis on hemodynamic parameters and respiratory
function in critically ill patients
Version:1Date:13 November 2013
Reviewer: Tony Bruns
Reviewer's report:
In this prospectively conducted cohort study Philip et al. determined effects of
paracentesis on hemodynamics and respiratory function in 50 critically ill
patients. They observed a decrease in MAD and SVRI 2 hours after paracentesis
and an immediate and prolonged effect on oxygenation and Lung Injury Score
consisting of oxygenation, PEEP and pulmonal compliance.
The authors conclude that paracentesis is safe and benefitial regarding pumonal
function in critically ill patients including patients with mechanical ventilation.
The manuscript is very well written and of interest for researchers in the field of
decompensated cirrhosis and critical care.
Before publication, the authors are encouraged to adress current concepts in
hepatology more in depth (pathophysiological discussion and neurohumoral
changes after LVP with respect to albumin substitution) and address a few
concerns to improve interpretation of the results:
1. Decompensated cirrhosis with portal hypertension represents a unique entity
with distinct marked hemodynamic and neurohumoral changes that profoundly
differs from ascites not due to portal hypertension. Only 44 of the 50 patients had
cirrhosis of the liver - what were reasons for ascites in the remaining 6 patients?
Is there data on SAAG or AF protein in cirrhotic patients to estimate the degree
of PH? I would recommend performing seperate analyses excluding the six
non-cirrhotic patients.
2. The authors observe a decrease in MAD 2 hrs. after paracentesis.
Paracentesis-induced circulatory dysfunction (PICD) is a common complication in
patients undergoing large volume paracentesis (>6 litres) that are not treated with
album/colloids. Of importance, PICD is often prolonged and observed up to the
6th day after paracentesis. The use of albumin (6-8 g/litre AF removed) reduces
PICD up to 75% (pooled OR 0.26 according to the recent meta-analysis by Kwok
et al.).
The authors cnclude that paracentesis does not alter hemodynamic status in
their cohort - please discuss the reasons for early changes in MAP and SVR and
recovery between 2 and 6 hours.
3. Since the median volume AF removed was 6 litres, 50% of patients received
LVP. I suggest comparing hemodynamics in the subgroup of patients undergoing
LVP with those not undergoing LVP to assess hemodynamic alterations in
patients at risk for PICD.
In addition, is it possible to provide how many patients with LVP received albumin
according to current guidelines, since it is likely that sufficient albumin use is
associated with less pronounced MAD reduction in patients undergoing LVP?
4. Using LIS as a surrogate of respiratory function could be misleading since it
results in a "truncated" discontinuous variable (range 4 to 7 in the study) - I would
suggest comparing the three used components of the LIS score seperately as
continuous variables. Performing a multivariate linear regression analysis with a
target variable that is discontinuous with four possible values (LIS after
paracentesis) using a closely related discontinuous variable (LIS before
paracentesis) is questionable. Is the model multivariate model including AF
volume and LIS of better discriminative performance than the model including AF
volume and PaO2/FiO2? If LIS is used as the parameter to be predicted, I would
suggest performing a logistic regression predicting improvement in LIS after
paracentesis instead (easier to interpret).
Minor points:
1. Do the authors have data on spectrum of disease leading to mechinal
ventilation and vasopressor use (variceal hemorrhage? sepsis? hepatic
encephalopathy), since some dieseases, e.g. SBP, might be associated with
increased suceptibility for PICD.
2. Do the authors have data on central-venous pressure before and after
paracentesis?
3. Do the authors have data on the subsequent development of acute kidney
injury in patients with and without LVP?
4. How many patients received vasopressors (according to the median less than
50%)? How many patients received beta-blockers?
5. Please omit BMI since its use in patients with ascites is limited.
6. Providing median (0) and IQR (0-0) for terlipressin dose in table 2 is of limited
information. Please omit.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a statistician.
Declaration of competing interests:
I declare that I have no competing interests