Endpoints of Resuscitation: What Should We Be Monitoring?

Goal-Directed Resuscitation Aiming Cardiac Index Masks Residual Hypovolemia: An Animal Experiment

The aim of this study was to compare stroke volume (SVI) to cardiac index (CI) guided resuscitation in a bleeding-resuscitation experiment. Twenty six pigs were randomized and bled in both groups till baseline SVI (T_bsl) dropped by 50% (T₀), followed by resuscitation with crystalloid solution until initial SVI or CI was reached (T₄). Similar amount of blood was shed but animals received significantly less fluid in the CI-group as in the SVI-group: median = 900 (interquartile range: 850–1780) versus 1965 (1584–2165) mL, p = 0.02, respectively. In the SVI-group all variables returned to their baseline values, but in the CI-group animals remained underresuscitated as indicated by SVI, heart rate (HR) and stroke volume variation (SVV), and central venous oxygen saturation (S_cvO₂) at T₄ as compared to T_bsl: SVI = 23.8 ± 5.9 versus 31.4 ± 4.7 mL, HR: 117 ± 35 versus 89 ± 11/min SVV: 17.4 ± 7.6 versus 11.5 ± 5.3%, and S_cvO₂: 64.1 ± 11.6 versus 79.2 ± 8.1%, p < 0.05, respectively. Our results indicate that CI-based goal-directed resuscitation may result in residual hypovolaemia, as bleeding caused stress induced tachycardia “normalizes” CI, without restoring adequate SVI. As the SVI-guided approach normalized most hemodynamic variables, we recommend using SVI instead of CI as the primary goal of resuscitation during acute bleeding.

The multimodal concept of hemodynamic stabilization

Hemodynamic instability often leads to hypoperfusion, which has a significant impact on outcome in both medical and surgical patients. Measures to detect and treat tissue hypoperfusion early by correcting the imbalance between oxygen delivery and consumption is of particular importance. There are several studies targeting different hemodynamic endpoints in order to investigate the effects of goal-directed therapy on outcome. A so-called multimodal concept putting several variables in context follows simple logic and may provide a broader picture. Furthermore, rather than treating population based "normal" values of certain indices, this concept can be translated into the individualized patient care to reach adequate oxygen supply and tissue oxygenation in order to avoid under, or over resuscitation, which are equally harmful. The purpose of this review is to give an overview of current data providing the basis of this a multimodal, individualized approach of hemodynamic monitoring and treatment.

Searching for the Holy Grail: a review of markers of tissue perfusion in pediatric critical care

Goal-directed therapy has become the key to resuscitating critically ill patients since 2001. However, the ideal marker to guide pediatric resuscitation has remained elusive.The ideal marker is specific, sensitive, easy to use, safe, validated, and cost-effective. Lactate and base deficit are validated prognosticators, but both are affected by confounding conditions and resuscitative efforts. Mixed venous oximetry has been successfully used for guiding therapy but requires a pulmonary artery catheter for measurement. Central venous oximetry, on the other hand, can be more easily measured and is now the standard of care in goal-directed therapy for adult septic shock. Pediatric literature related to central venous oximetry is still in relative infancy, but seems promising. Sublingual capnometry may also prove to be useful, but no pediatric research has been published related to this device. Finally, near-infrared spectroscopy monitoring may be useful in highlighting changes in patient conditions, but its use in goal-directed therapy is limited by the wide interpatient variability. In summary, the search for the ideal marker of tissue perfusion continues, but there is promise on the horizon.