PVI, an automatic and continuous monitor of DeltaPOP, can predict fluid responsiveness non-invasively in mechanically ventilated patients during general anaesthesia. This index has potential clinical applications.

DeltaPOP can predict fluid responsiveness noninvasively in mechanically ventilated patients during general anesthesia. This index has potential clinical applications.

EudraCT Number: 2012-000232-25; clinicaltrials.gov Identifier: NCT02184819.

During septic shock, muscle produces lactate by way of an exaggerated NaK-adenosine triphosphatase (ATPase)-stimulated aerobic glycolysis associated with epinephrine stimulation possibly through beta2 adrenoreceptor involvement. It therefore seems logical that a proportion of hyperlactatemia in low cardiac output states would be also related to this mechanism. Thus, in low-flow and normal-to-high-flow models of shock, we investigate (1) whether muscle produces lactate and (2) whether muscle lactate production is linked to beta2 adrenergic stimulation and Na+K+-ATPase. We locally modulated the adrenergic pathway and Na+K+-ATPase activity in male Wistar rats' skeletal muscle using microdialysis with nonselective and selective beta blockers and ouabain in different models of rodent shock (endotoxin, peritonitis, and hemorrhage). Blood flow at the probe site was evaluated by ethanol clearance. We measured the difference between muscle lactate and blood lactate concentration, with a positive gradient indicating muscle lactate or pyruvate production. Epinephrine levels were elevated in all shock groups. All models were associated with hypotension and marked hyperlactatemia. Muscle lactate concentrations were consistently higher than arterial levels, with a mean gradient of 2.5+/-0.3 in endotoxic shock, 2.1+/-0.2 mM in peritonitis group, and 0.9+/-0.2 mM in hemorrhagic shock (P<0.05 for all groups). Muscle pyruvate concentrations were also always higher than arterial levels, with a mean gradient of 260+/-40 microM in endotoxic shock, 210+/-30 microM in peritonitis group, and 90+/-10 microM in hemorrhagic shock (P<0.05 for all groups). Despite a decrease in blood flow, lactate formation was decreased by all the pharmacological agents studied irrespective of shock mechanism. This demonstrates that lactate production during shock states is related, at least in part, to increased NaK-ATPase activity under beta2 stimulation. In shock state associated with a reduced or maintained blood flow, an important proportion of muscle lactate release is regulated by a beta2 receptor stimulation and not secondary to a reduced oxygen availability.

SVV predicts fluid responsiveness with an acceptable sensitivity and specificity and is also a potential surrogate for continuous monitoring of DeltaPP.

IntroductionPulse pressure variation (PPV) has been shown to predict fluid responsiveness in ventilated intensive care unit (ICU) patients. The present study was aimed at assessing the diagnostic accuracy of PPV for prediction of fluid responsiveness by using the grey zone approach in a large population.MethodsThe study pooled data of 556 patients from nine French ICUs. Hemodynamic (PPV, central venous pressure (CVP) and cardiac output) and ventilator variables were recorded. Responders were defined as patients increasing their stroke volume more than or equal to 15% after fluid challenge. The receiver operating characteristic (ROC) curve and grey zone were defined for PPV. The grey zone was evaluated according to the risk of fluid infusion in hypoxemic patients.ResultsFluid challenge led to increased stroke volume more than or equal to 15% in 267 patients (48%). The areas under the ROC curve of PPV and CVP were 0.73 (95% confidence interval (CI): 0.68 to 0.77) and 0.64 (95% CI 0.59 to 0.70), respectively (P <0.001). A grey zone of 4 to 17% (62% of patients) was found for PPV. A tidal volume more than or equal to 8 ml.kg−1 and a driving pressure (plateau pressure - PEEP) more than 20 cmH2O significantly improved the area under the ROC curve for PPV. When taking into account the risk of fluid infusion, the grey zone for PPV was 2 to 13%.ConclusionsIn ventilated ICU patients, PPV values between 4 and 17%, encountered in 62% patients exhibiting validity prerequisites, did not predict fluid responsiveness.

Cardiac output (CO) measurement is crucial for the guidance of therapeutic decisions in critically ill and high-risk surgical patients. Newly developed completely non-invasive CO technologies are commercially available; however, their accuracy and precision have not recently been evaluated in a meta-analysis. We conducted a systematic search using PubMed, Cochrane Library of Clinical Trials, Scopus, and Web of Science to review published data comparing CO measured by bolus thermodilution with commercially available non-invasive technologies including pulse wave transit time, non-invasive pulse contour analysis, thoracic electrical bioimpedance/bioreactance, and CO2 rebreathing. The non-invasive CO technology was considered acceptable if the pooled estimate of percentage error was <30%, as previously recommended. Using a random-effects model, sd, pooled mean bias, and mean percentage error were calculated. An I2 statistic was also used to evaluate the inter-study heterogeneity. A total of 37 studies (1543 patients) were included. Mean CO of both methods was 4.78 litres min−1. Bias was presented as the reference method minus the tested methods in 15 studies. Only six studies assessed the random error (repeatability) of the tested device. The overall random-effects pooled bias (limits of agreement) and the percentage error were −0,13 [−2.38 , 2.12] litres min−1 and 47%, respectively. Inter-study sensitivity heterogeneity was high (I2=83%, P<0.001). With a wide percentage error, completely non-invasive CO devices are not interchangeable with bolus thermodilution. Additional studies are warranted to demonstrate their role in improving the quality of care.

For elderly patients, 6-month mortality better reflects the burden of mitral surgery than the usual 1-month mortality. Even though replacement patients have higher operative estimated risk, mitral replacement remains, after adjustment, an independent predictor of higher operative mortality. Our results claim for wider use of repair technique in mitral surgery for the octogenarians, even if replacement is an acceptable option when repair is technically uncertain.