Meta-analysis of hemodynamic optimization: relationship to methodological quality

Abstract

Introduction: To review systematically the effect of interventions aimed at hemodynamic optimization and to relate this to the quality of individual published trials.

Methods: A systematic, computerized bibliographic search of published studies and citation reviews of relevant studies was performed. All randomized clinical trials in which adult patients were included in a trial deliberately aiming at an optimized or maximized hemodynamic condition of the patients (with oxygen delivery, cardiac index, oxygen consumption, mixed venous oxygen saturation and/or stroke volume as end-points) were selected. A total of 30 studies were selected for independent review. Two reviewers extracted data on population, intervention, outcome and methodological quality. Agreement between reviewers was high: differences were eventually resolved by third-party decision. The methodological quality of the studies was moderate (mean 9.0, SD 1.7), and the outcomes of the randomized clinical trials were not related to their quality.

Results: Efforts to achieve an optimized hemodynamic condition resulted in a decreased mortality rate (relative risk ratio (RR) 0.75 (95% confidence interval (CI) 0.62 to 0.90) in all studies combined. This was due to a significantly decreased mortality in peri-operative intervention studies (RR 0.66 (95% CI 0.54 to 0.81). Overall, patients with sepsis and overt organ failure do not benefit from this method (RR 0.92 (95% CI 0.75 to 1.11)).

Conclusion: This systematic review showed that interventions aimed at hemodynamic optimization reduced mortality. In particular, trials including peri-operative interventions aimed at the hemodynamic optimization of high-risk surgical patients reduce mortality. Overall, this effect was not related to the trial quality.

Figure 1

Relative risk determined in individual trials in studies (including subset analysis with patients treated peri-operatively and patients with sepsis and/or organ failure) shown as boxes scaled according to weighting, using the inverse variance method. Error bars indicate 95% confidence intervals (95% CI). A fixed-effects model (peri-operative studies) was used when heterogeneity analysis was not significant, and a random-effects model (sepsis and total included studies) was used when heterogeneity analysis was significant. The pooled relative risk estimates are shown as diamonds that span the 95% CI. n, number of deceased patients in the treatment or control arm; N, total number of patients in treatment or control arm; RR, relative risk ratio.