Bundgaard-Nielsen M, Ruhnau B, Secher NH, Kehlet H: Flow-related techniques for preoperative goal-directed fluid optimization
Improved postoperative outcome has been demonstrated by perioperative maximization of cardiac stroke volume (SV) with fluid challenges, so-called goal-directed therapy. Oesophageal Doppler (OD) has been the most common technique for goal-directed therapy, but other flow-related techniques and parameters are available and they are potentially easier to apply in clinical practice. The objective of this investigation was therefore to use OD for preoperative SV maximization and compare the findings with a Modelflow determined SV, with an OD estimated corrected flow time (FTc), with central venous oxygenation ( Svo2 ) and with muscle and brain oxygenation assessed with near infrared spectroscopy (NIRS).
Twelve patients scheduled for radical prostatectomy were anaesthetized before optimization of SV estimated by OD. A fluid challenge of 200 ml colloid was provided and repeated if at least a 10% increment in OD SV was obtained. Values were compared with simultaneously measured values of Modelflow SV, FTc, Svo2 and muscle and cerebral oxygenation estimated by NIRS.
Based upon OD assessment, optimization of SV was achieved after the administration of 400-800 ml (mean 483 ml) of colloid. The hypothetical volumes administered for optimization based upon Modelflow and Svo2 differed from OD in 10 and 11 patients, respectively. Changes in FTc and NIRS were inconsistent with OD guided optimization.
Preoperative SV optimization guided by OD for goal-directed therapy is preferable compared with Modelflow SV, FTc, NIRS and Svo2 until outcome studies for the latter are available.
Available from: Jonathan Ball
- "After further screening of titles and abstracts against our inclusion criteria, 85 references were retrieved for full text analysis. Detailed full text evaluation excluded 13 studies, as they were not randomized controlled trials [11-23]. Analysis of the remaining 72 randomized controlled trials produced the following exclusions: studies focusing on fluid management strategies (that is, liberal versus restrictive) [24-33], use of 'fixed dose' inotropic agents not titrated to a predetermined goal [34-38], cardiac surgery [39-44], trauma [45-52], paediatric surgery  and critically ill medical populations [54-62]. "
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ABSTRACT: Patients with limited cardiac reserve are less likely to survive and develop more complications following major surgery. By augmenting oxygen delivery index (DO2I) with a combination of intravenous fluids and inotropes (goal directed therapy (GDT)), postoperative mortality and morbidity of high-risk patients may be reduced. However, although most studies suggest that GDT may improve outcome in high-risk surgical patients, it is still not widely practiced. We set out to test the hypothesis that GDT results in greatest benefit in terms of mortality and morbidity in patients with the highest risk of mortality and have undertaken a systematic review of the current literature to see if this is correct. We performed a systematic search of Medline, Embase and CENTRAL databases for randomized controlled trials (RCTs) and reviews of GDT in surgical patients. To minimize heterogeneity we excluded studies involving cardiac, trauma, and paediatric surgery. Extremely high risk, high risk and intermediate risks of mortality were defined as >20%, 5 to 20% and <5% mortality rates in the control arms of the trials, respectively. Meta analyses were performed and Forest plots drawn using RevMan software. Data are presented as odd ratios (OR; 95% confidence intervals (CI), and P-values). A total of 32 RCTs including 2,808 patients were reviewed. All studies reported mortality. Five studies (including 300 patients) were excluded from assessment of complication rates as the number of patients with complications was not reported. The mortality benefit of GDT was confined to the extremely high-risk group (OR = 0.20, 95% CI 0.09 to 0.41; P < 0.0001). Complication rates were reduced in all subgroups (OR = 0.45, 95% CI 0.34 to 0.60; P < 0.00001). The morbidity benefit was greatest amongst patients in the extremely high-risk subgroup (OR = 0.27, 95% CI 0.15 to 0.51; P < 0.0001), followed by the intermediate risk subgroup (OR = 0.43, 95% CI 0.27 to 0.67; P = 0.0002), and the high-risk subgroup (OR 0.56, 95% CI 0.36 to 0.89; P = 0.01). Despite heterogeneity in trial quality and design, we found GDT to be beneficial in all high-risk patients undergoing major surgery. The mortality benefit of GDT was confined to the subgroup of patients at extremely high risk of death. The reduction of complication rates was seen across all subgroups of GDT patients.
Available from: Berend E Westerhof
- "For a transthoracic approach the Doppler probe has to be held over the root of the aorta requiring a skilled operator and constancy of probe angle to minimize bias . Nonetheless, esophageal Doppler has been shown to give positive results in goal-directed therapy [91–93]. "
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ABSTRACT: Monitoring of continuous blood pressure and cardiac output is important to prevent hypoperfusion and to guide fluid administration, but only few patients receive such monitoring due to the invasive nature of most of the methods presently available. Noninvasive blood pressure can be determined continuously using finger cuff technology and cardiac output is easily obtained using a pulse contour method. In this way completely noninvasive continuous blood pressure and cardiac output are available for clinical use in all patients that would otherwise not be monitored. Developments and state of art in hemodynamic monitoring are reviewed here, with a focus on noninvasive continuous hemodynamic monitoring form the finger.
Available from: Miklos Lipcsey
- "Although there is an extensive literature on NIRS used before , during [42-45] or after surgery [46,47], relatively little has been published on NIRSth during the perioperative period. However, in a recent publication Rres, measured in patients undergoing major abdominal surgery patients, was decreased in fluid responsive patients . "
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ABSTRACT: Near infrared spectroscopy of the thenar eminence (NIRSth) is a noninvasive bedside method for assessing tissue oxygenation. The NIRS probe emits light with several wavelengths in the 700- to 850-nm interval and measures the reflected light mainly from a predefined depth. Complex physical models then allow the measurement of the relative concentrations of oxy and deoxyhemoglobin, and thus tissue saturation (StO2), as well as an approximation of the tissue hemoglobin, given as tissue hemoglobin index.
Here we review of current knowledge of the application of NIRSth in anesthesia and intensive care.
We performed an analytical and descriptive review of the literature using the terms “near-infrared spectroscopy” combined with “anesthesia,” “anesthesiology,” “intensive care,” “critical care,” “sepsis,” “bleeding,” “hemorrhage,” “surgery,” and “trauma” with particular focus on all NIRS studies involving measurement at the thenar eminence.
We found that NIRSth has been applied as clinical research tool to perform both static and dynamic assessment of StO2. Specifically, a vascular occlusion test (VOT) with a pressure cuff can be used to provide a dynamic assessment of the tissue oxygenation response to ischemia. StO2 changes during such induced ischemia-reperfusion yield information on oxygen consumption and microvasculatory reactivity. Some evidence suggests that StO2 during VOT can detect fluid responsiveness during surgery. In hypovolemic shock, StO2 can help to predict outcome, but not in septic shock. In contrast, NIRS parameters during VOT increase the diagnostic and prognostic accuracy in both hypovolemic and septic shock. Minimal data are available on static or dynamic StO2 used to guide therapy.
Although the available data are promising, further studies are necessary before NIRSth can become part of routine clinical practice.
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