Tag Archives: shock

Lactate clearance goal in sepsis

Previous work in severe sepsis/septic shock patients has shown that a decrease in lactate concentration by at least 10% during emergency department resuscitation predicts survival. Since this is a potential alternative resuscitation goal to a central venous oxygen saturation (ScvO2) of 70% (as per surviving sepsis campaign guidelines), lactate clearance was compared with ScvO2 in a randomised non-inferiority trial of 300 patients.

All patients were managed in the ED and received fluids, antibiotics, and vasopressors as needed. Then lactate clearance or ScvO2 were measured, and if the respective goals of 10% or 70% were not met, packed cells or dobutamine were given depending on haematocrit. Lactate clearance was the percentage decrease in lactate between two venous specimens taken two hours apart.

Interestingly only 29 patients received either packed cells or dobutamine. Each group was similar in terms of time to antibiotic therapy and amount of fluid given. Patients in the group resuscitated to a lactate clearance of 10% or higher had 6% lower in-hospital mortality than those resuscitated to an ScvO2 of at least 70% (95% CI for this difference, –3% to 15%) exceeding the –10% predefined noninferiority threshold.

The authors conclude ‘these data support the substitution of lactate measurements in peripheral venous blood as a safe and efficacious alternative to a computerized spectrophotometric catheter in the resuscitation of sepsis.’

Lactate clearance vs central venous oxygen saturation as goals of early sepsis therapy: a randomized clinical trial
JAMA. 2010 Feb 24;303(8):739-46

Noradrenaline vs Dopamine in Shock

Another nail in dopamine’s coffin? In a blinded randomised controlled trial in shocked patients1, there was no difference in mortality when dopamine was compared with noradrenaline as the initial vasopressor. However the dopamine group had a significantly higher incidence of dysrythmia. In addition, mortality was higher in the predefined subgroup of 280 patients with cardiogenic shock. The results of this European study of 1679 patients are very similar to those of a similar but open-label American trial in 252 patients published recently2.

1. Comparison of Dopamine and Norepinephrine in the Treatment of Shock
NEJM 2010;362(9):779-89

2. Efficacy and Safety of Dopamine versus Norepinephrine in the Management of Septic Shock
Shock. 2009 Oct 21. [Epub ahead of print]

Effect on noradrenaline on tissue oxygen delivery

Some persist in thinking and teaching that the ‘vasopressor’ noradrenaline (norepinephrine) increases mean arterial pressure (MAP) simply by increasing systemic vascular resistance, leading to concerns that it may increase blood pressure at the expense of tissue perfusion. This assertion is contested by many, who now have further support from this study.

In 16 patients with septic shock, various measures of peripheral perfusion were recorded while the dose of noradrenaline was increased to achieve target MAPs. The use of noradrenaline to achieve incremental targets for MAP was associated with increases in global oxygen delivery, cutaneous microvascular flow, and tissue oxygenation in patients with established septic shock; there were no associated changes in the preexisting abnormalities of sublingual microvascular flow. The authors state that these findings suggest that in patients with septic shock, improvements in global hemodynamics and tissue oxygen delivery can be achieved with noradrenaline, without exacerbating microcirculatory flow abnormalities.

The effect of increasing doses of norepinephrine on tissue oxygenation and microvascular flow in patients with septic shock
Crit Care Med. 2009 Jun;37(6):1961-6

End expiratory occlusion

OBJECTIVE: During mechanical ventilation, inspiration cyclically decreases the left cardiac preload. Thus, an end-expiratory occlusion may prevent the cyclic impediment in left cardiac preload and may act like a fluid challenge. We tested whether this could serve as a functional test for fluid responsiveness in patients with circulatory failure.

DESIGN: Prospective study.

SETTING: Medical intensive care unit.

PATIENTS: Thirty-four mechanically ventilated patients with shock in whom volume expansion was planned.

INTERVENTION: A 15-second end-expiratory occlusion followed by a 500 mL saline infusion.

MEASUREMENTS: Arterial pressure and pulse contour-derived cardiac index (PiCCOplus) at baseline, during passive leg raising (PLR), during the 5-last seconds of the end-expiratory occlusion, and after volume expansion.

MAIN RESULTS: Volume expansion increased cardiac index by >15% (2.4 +/- 1.0 to 3.3 +/- 1.2 L/min/m, p < 0.05) in 23 patients ("responders"). Before volume expansion, the end-expiratory occlusion significantly increased arterial pulse pressure by 15% +/- 15% and cardiac index by 12% +/- 11% in responders whereas arterial pulse pressure and cardiac index did not change significantly in nonresponders. Fluid responsiveness was predicted by an increase in pulse pressure >or=5% during the end-expiratory occlusion with a sensitivity and a specificity of 87% and 100%, respectively, and by an increase in cardiac index >or=5% during the end-expiratory occlusion with a sensitivity and a specificity of 91% and 100%, respectively. The response of pulse pressure and cardiac index to the end-expiratory occlusion predicted fluid responsiveness with an accuracy that was similar to the response of cardiac index to PLR and that was significantly better than the response of pulse pressure to PLR (receiver operating characteristic curves area 0.957 [95% confidence interval [CI:] 0.825-0.994], 0.972 [95% CI: 0.849-0.995], 0.937 [95% CI: 0.797-0.990], and 0.675 [95% CI: 0.497-0.829], respectively).

CONCLUSIONS:The hemodynamic response to an end-expiratory occlusion can predict volume responsiveness in mechanically ventilated patients.

Predicting volume responsiveness by using the end-expiratory occlusion in mechanically ventilated intensive care unit patients.
Crit Care Med. 2009 Mar;37(3):951-6