2,833 publications from this institution
Dellinger, R Phillip MD, FCCM; Rhodes, Andrews MD; Vincent, Jean-Louis MD, PhD Author Information
Introduction: Hypercapnia may cause hemodynamic improvement in septic shock due to neuroadrenal stimulation. The aim of this study was to investigate whether hypercapnia has similar effects to dobutamine in a clinically relevant model of septic shock. Methods: Twenty-one anesthetized, mechanically ventilated, invasively monitored female sheep (BW: 27.5  2.5 Kg) received 1.5 g/kg body weight feces intraperitoneally to induce septic shock. Ringer's lactate and 6% hydroxyethyl starch solutions were infused throughout the experiment to sustain normovolemia. No antibiotics or vasoactive agents were used. Two hours after injection of feces, animals were randomized to one of three groups: Hypercapnia: carbon dioxide was given at FiCO2 of 4.1% throughout the experiment to maintain PaCO2 between 55 and 65 mmHg; dobutamine: dobutamine was infused intravenously at a dose of 7 g/kg/min throughout the experiment; control: no treatment. In the dobutamine and control groups, PaCO2 was maintained between 35 and 45 mmHg. All animals were monitored until spontaneous death. Result: All animals developed a hyperdynamic phase associated with an increase in pulmonary vascular resistance, and lactic acidosis. PaCO2 was significantly higher in the hypercapnia group than in the other two groups (P < 0.05). Animals in the hypercapnia and dobutamine groups maintained higher mean arterial pressure, higher stroke volume, higher heart rate and higher oxygen delivery than the control animals; they also had lower lactate concentrations (P < 0.05). There were no differences in these parameters between the hypercapnia and dobutamine groups. Animals treated with hypercapnia had a higher PaO2/FiO2 and lower wet/dry ratio than the other two groups. There were no differences in survival times in the three groups (P = 0.65). Conclusion: Hypercapnia improved gas exchange, decreased pulmonary edema formation and induced similar hemodynamic effects to dobutamine infusion in this clinically relevant model of septic shock in sheep.
We collected all complete sets of measurements of cardiac index and oxygen-derived variables available in the recent literature (1975-1991; computerised Medline search) on critically ill patients with sepsis (n=21 studies), septic shock (n=20 studies) or severe heart failure (n=13 studies). For each study, the mean value for cardiac index, oxygen delivery (DO 2), oxygen uptake (VO 2), oxygen extraction ratio (O 2ER) and lactate concentration (when available) were analysed together with mortality rates. There was a significant relationship between VO 2 and DO 2 for the studies on patients with severe heart failure (r=0.79, p less than 0.001) or septic shock (r=0.55, p less than 0.01), but not in patients with sepsis (r=0.3, p=NS). As expected, O 2ER was higher in the studies in heart failure (31 to 50%) than in septic shock (25 to 45%) or sepsis (19 to 40%). When compared to the studies on patients with sepsis, the studies in septic shock included patients with lower DO 2 (481+/-89 vs 539+/-79 ml/min.M 2, p=0.032) and higher O 2ER (32.5+/-5.2 vs 27.8+/-5.0%, p less than 0.01) but similar VO 2 (143+/-29 vs 143+/-19 ml/min.M 2, p=NS). In a cardiac index/O 2ER diagram where a line of reference represents proportional changes in cardiac index and O 2ER from normal values at rest, all studies in heart failure fell below the line of reference. The majority of studies in sepsis (18/21) fell above the line of reference. Interestingly, only nine of the 20 studies in septic shock fell above this line. The review of the 14 studies in septic shock, in which O 2ER and blood lactate were reported, showed a direct relationship between these two variables (r=0.68, p less than 0.01), but no relationship between cardiac index and blood lactate (r=0.37, p=NS). This analysis suggests that patients with septic shock tend to have a lower cardiac index and higher O 2ER than septic patients who are haemodynamically stable. Furthermore, the positive relationship between O 2ER and lactate suggests that, despite the alterations in oxygen extraction capabilities in severe sepsis, mean O 2ER may be higher in the most severe cases of septic shock. This could reflect an attempt to maintain VO 2 when DO 2 is insufficient. The prevailing opinion that 0 2ER is a meaningless variable in septic shock needs to be reassessed.
3 and suggest an evidence-based algorithm, which essentially does not foresee supplemental parenteral nutrition (SPN) before days 5-7 after intensive care unit (ICU) admission, even in patients with contra-indication for enteral nutrition. 1 Furthermore, they state that SPN probably should be restricted to the most severely ill patients (possible long stayers), and in patients with malnutrition SPN
Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA; (Pinsky) Department of Intensive Care, Erasme University Hospital, Brussels, Belgium (Vincent)
Sepsis is a common cause of morbidity and mortality among the critically ill patient population. However, no anti-sepsis therapy has yet been found to be effective and treatment is thus largely supportive. Adequate fluid resuscitation must be accompanied by effective ventilation, and adrenergic agents may be needed to restore perfusion pressure and improve myocardial function. Enteral nutritional support with specialized nutrients has beneficial effects on morbidity, and should be started early. Further research will allow better definition of the septic patient according to immune status and enable more effective targeting of future anti-sepsis treatments.
Despite a usually normal or high cardiac output, severe sepsis is associated with inadequate tissue oxygenation, leading to organ failure and death. Some authors have suggested that raising cardiac output and oxygen delivery to predetermined supranormal values may be associated with improved survival. While this may be of benefit in certain patients, bringing all patients to similar, supranormal values, is simplistic. It is much preferable to titrate therapy according to the needs of each individual patient. A combination of variables should be used for this purpose, in addition to a careful clinical evaluation, including not only cardiac output but also the mixed venous oxygen saturation and the blood lactate concentrations. The concept is to assess the adequacy of the cardiac output in patients with severe sepsis, enabling management strategies aimed at optimizing cardiac output to be tailored to the individual patient.
