Hemodynamic Responses to Crystalloid and Colloid Fluid Boluses during Noncardiac Surgery

The Effect of Colloids versus Crystalloids for Goal-Directed Fluid Therapy on Prognosis in Patients Undergoing Noncardiac Surgery: A Meta-Analysis of Randomized Controlled Trials

Background

Goal-directed fluid therapy (GDFT) contributes to improvements in intraoperative fluid infusion based on objective parameters and has been widely recommended in clinical practice. In addition, increasing evidence reveals that GDFT can improve the prognosis of surgical patients. However, considering the individual characteristics of colloids and crystalloids in clinical use, it is uncertain as to which type of fluids administered is associated with better outcomes in the condition of GDFT.

Objectives

To evaluate the effect of colloids versus crystalloids under GDFT on prognosis in patients undergoing noncardiac surgery. Data Sources. Randomized controlled trials (RCTs) from PubMed, EMBASE, Ovid MEDLINE, CNKI, Cochrane library, and reference lists of relevant articles.

Methods

Two investigators independently screened and reviewed studies for inclusion and performed data extraction. Our primary outcome was a composite of postoperative complications. The secondary outcomes were (1) mortality at the follow-up duration; (2) postoperative complications of several organ systems, including cardiac, pulmonary, digestive, urinary, nervous system, and postoperative infection events; and (3) hospital and ICU length of stay. Heterogeneity was assessed by the I 2 and chi-square tests. The odds ratio (OR) of the dichotomous data, mean difference (MD) of continuous data, and 95% confidence intervals (CI) were calculated to assess the pooled data.

Results

Of 332 articles retrieved, 15 RCTs (involving 2,956 patients undergoing noncardiac surgery) were included in the final analysis. When the data were pooled, patients in the colloids and crystalloids group revealed no difference in postoperative composite complications (OR = 0.84, 95% CI = 0.51-1.38, P=0.49) under GDFT. Regarding the secondary outcomes, patients in the colloids group were associated with fewer digestive system complications (OR = 0.64, 95% CI = 0.41-0.98, P=0.04). However, no difference was found in mortality (OR = 1.37, 95% CI = 0.72-2.58, P=0.34), complications of the cardiac system (OR = 1.49, 95% CI = 0.66-3.37, P=0.34), pulmonary system (OR = 0.89, 95% CI = 0.62-1.28, P=0.53), urinary system (OR = 1.05, 95% CI = 0.61-1.80, P=0.87), nervous system (OR = 1.04, 95% CI = 0.55-1.98, P=0.90), postoperative infection events (OR = 0.89, 95% CI = 0.75-1.07, P=0.22), length of hospital stay (difference in mean = -0.71, 95% CI = -1.49-0.07, P=0.07), and ICU stay (difference in mean = -0.01, 95% CI = -0.20-0.18, P=0.95) between patients receiving GDFT with colloids or crystalloids.

Conclusion

There is no evidence of a benefit in using colloids over crystalloids under GDFT in patients undergoing noncardiac surgery, despite its use resulting in lower digestive system complications.

A randomised controlled feasibility trial of a clinical protocol to manage hypotension during major non-cardiac surgery

Intra-operative hypotension is a risk factor for postoperative morbidity and mortality. Minimally invasive monitors that derive other haemodynamic parameters, such as stroke volume, may better inform the management of hypotension. As a prelude to a multicentre randomised controlled trial, we conducted a single-centre feasibility trial of a protocol to treat hypotension as informed by minimally invasive haemodynamic monitoring during non-cardiac surgery. We recruited adults aged ≥40 years with cardiovascular risk factors who underwent non-cardiac surgery requiring invasive arterial pressure monitoring. Participants were randomly allocated to usual care, or a clinical protocol informed by an arterial waveform contour analysis monitor. Participants, outcome assessors, clinicians outside operating theatres and analysts were blinded to treatment allocation. Feasibility was evaluated based on: consent rate; recruitment rate; structured feedback from anaesthesia providers; and between-group differences in blood pressure, processes-of-care and outcomes. The consent rate among eligible patients was 33%, with 30 participants randomly allocated to the protocol and 30 to usual care. Anaesthesia providers rated the protocol to be feasible and acceptable. The protocol was associated with reduced fluid balance and hypotension exposure in the peri-operative setting. Postoperative complications included: acute myocardial injury in 18 (30%); acute kidney injury in 17 (28%); and surgical site infection in 7 (12%). The severity of complications was rated as moderate or severe in 25 (42%) participants. In summary, this single-centre study confirmed the feasibility of a multicentre trial to assess the efficacy and safety of a physiologically guided treatment protocol for intra-operative hypotension based on minimally invasive haemodynamic monitors.