Article Review

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Joosten, A., Delaporte, A., Ickx, B., Touihri, K., Stany, I., Barvais, L.,  & Van der Linden, P. (2018). Crystalloid versus Colloid for Intraoperative Goal-directed Fluid Therapy Using a Closed-loop System. A Randomized, Double-blinded, Controlled Trial in Major Abdominal Surgery. Anesthesiology: The Journal of the American Society of Anesthesiologists, 128(1), 55-66.

Article Review

The purpose of this study was to evaluate post-operative outcome in patients undergoing major elective abdominal surgery in crystalloid versus colloid fluids when using a closed-loop assisted goal-directed fluid therapy.  The authors hypothesized that there would be fewer post-operative complications when using a balanced colloid solution (Joosten et al., 2018).  The hypothesis was tested using a two-arm, parallel, randomized controlled, double blind, bi-center superiority study.  This was the first study to evaluate the effects of crystalloid versus colloid fluids when using a closed-loop assisted goal-directed fluid therapy. 

The study consisted of 160 patients randomized into a colloid and crystalloid group.  To be included in the study, the patients were required to be over 18 year’s old undergoing elective abdominal surgery greater than 3 hours duration.  Additionally, 10 subjects were excluded from the study due to underlying conditions such as coagulation disorders, renal insufficiency and impaired hepatic function.  A closed-loop system was used for real time monitoring of stroke volume, stroke volume variation, heart rate, and MAP to optimize a patient’s fluid status. All fluid bags were labeled by patient number to keep the study blind to the subjects and physicians attending.  The primary outcome was Post-Operative Morbidity Survey Score (POMS), and was determined after two days post-surgery by two investigators that remained blinded to the group allocation.  The POMS score included nine diagnostic domains including pulmonary, infectious, renal, cardiovascular, gastrointestinal, neurologic, hematologic, wound, and pain.  Secondary outcomes were post-operative complications that occurred within 30 days of surgery (Joosten et al., 2018).

Intraoperative data collected included time of anesthesia, time of surgery, fluid volumes and net fluid balance, urine output, estimated blood loss and amount vasopressors utilized. A Kolmogorov-Smirnov test was used to analyze data for normality.  Since the data was not normally distributed, the results of the study were reported as a median and interquartile range and comparisons were made using a Mann-Whitney U test.  The data was presented as percentages and compared using a chi square or fisher exact test if indicated, with a significance being P<0.05.

The total fluid volume used in the crystalloid group was 1500mL with an interquartile range of 800 to 2500mL and 900mL, with a range of 400 to 1300mL in the colloid group.  The colloid group also had significantly lower study fluid volume, total amount of fluid and net fluid balance when compared to the crystalloid group (P<0.001). The use of vasopressors, heart rate, and SVV were all significantly lower in the colloid group (P<0.001).  MAP was found to be significantly higher in the colloid versus crystalloid group (P=0.036).  The POMS survey score and incidence of complications were significantly lower in the colloid group (P<0.001) .  Interestingly, the incidence of anastomotic leakage that occurred following a resection and anastomosis was significantly higher in the crystalloid group.  Significantly fewer patients in the colloid group had lactate levels greater than 2meq/L when compared to the colloid group (Joosten et al., 2018).  There was no difference found between renal function, length of hospital stay and the number of intraoperative fluid boluses needed between groups.

The results of the study confirmed the author’s hypothesis that a colloid-based goal directed fluid therapy was associated with lower POMS score and fewer post-operative complications compared to crystalloid fluids when using a closed loop system in patients undergoing major elective abdominal surgery.  This differs from two previous studies performed that showed no significant difference between fluid types, however, they did not use a closed loop system for goal directed therapy (insert citation).  Due to the use of a closed loop system in the current study, optimizing central cardiovascular variables, the authors were unable to differentiate if the lower fluid volume and net fluid balance observed in the colloid group was a result of the type of fluid used, total fluid volume, or a combination of both (Joosten et al., 2018).  The use of a closed loop system eliminated any intervention bias between groups that occurred in previous studies (insert citation).  This system also improves compliance and accuracy of implementation, while computers eliminated any decreased vigilance that can occur when humans conduct repetitive, attention-based work.  Goal directed fluid therapy is not commonly implicated in practice due to the amount of training and attention to detail required leading to compliance rates being 50% or less (insert citation).  The limitations of the study were: procedures in the crystalloid group lasted about one hour longer; the ratio of intravascular volume between fluid types is still debated depending on the clinical situation; only short-term outcomes were evaluated; the POMS score utilized was underpowered to detect renal function and mortality rate; and being a small trial, it is prone to type 1 error.