Systemic oxygen extraction can be improved during repeated episodes of cardiac tamponade

We used a tamponade model to study the relationship between oxygen uptake (Vo2) and oxygen delivery (Do2) during successive, reversible decreases in blood flow. In 7 pentobarbital-anesthetized and mechanically ventilated dogs, a catheter was introduced via a left thoracotomy into the pericardium to inject and to withdraw saline. Each experiment consisted of three steps. First, cardiac output was reduced by successive pericardial fluid injections until 4 to 6 data points were obtained in the dependent region of the Vo2/Do2 plot (step 1). Second, cardiac output was restored by progressive withdrawal of pericardial fluid (step 2). Third, cardiac output was lowered again by reinjection of fluid into the pericardium until death (step 3). Expired gases were collected for determination of Vo2. In each animal, critical Do2 (Do2crit), below which Vo2 became Do2 dependent, was determined from a plot of Vo2 versus Do2. When releasing tamponade, Vo2 was restored to baseline. For the 3 steps, Do2crit were 10.5 ± 2.2 mL/kg/min in step 1, 9.8 ± 1.8 mL/kg/min in step 2, and 8.3 ± 1.9 mL/kg/min in step 3 (P < .01 v step 1; P < .05 v step 2, respectively). There was no significant difference in Vo2 at Do2crit for the three steps. Hence, critical oxygen extraction ratio (ERo2crit) increased from 60% ± 12% in step 1 to 64% ± 11% in step 2 (not significant) and to 73% ± 12% in step 3 (P < .01). The Vo2/Do2 dependency slope was also steeper in step 3 than in step 1 (0.77 ± 0.31 v 0.54 ± 0.20, P < .05). A progressive decrease in arterial and in mixed venous pH was observed during the experiment. We conclude that a decrease in Vo2 associated with an acute reduction in blood flow can be readily reversible. When the procedure is repeated, a progressive increase in oxygen extraction capabilities is observed. This reversible tamponade model is potentially suitable to induce several hypoxic episodes in the same animal.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Prostaglandin E1 increases oxygen extraction capabilities in experimental sepsis

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Analysis of particulate exposure during continuous drug infusion in critically ill adult patients: a preliminary proof-of-concept in vitro study.

In critically ill patients, drug incompatibilities frequently occur because of the number of drugs to be administered through a limited number of infusion lines. These are among the main causes of particulate contamination. However, little data is available to quantify particle exposure during simultaneous IV-drug infusion. The objective of this study was to evaluate the particulate matter potentially administered to critically ill patients. The particulate matter (between 1 μm and 30 mm) of infused therapies used in ICUs for patients suffering from either septic shock or acute respiratory distress syndrome was measured in vitro over 6 h using a dynamic image analysis device, so that both overall particulate contamination and particle sizes could be determined. Data is presented according to the recommendations of the European Pharmacopoeia (≥ 10 and 25 μm). For the six experimental procedures (continuous infusion of norepinephrine, midazolam, sufentanil, heparin, 5% glucose, binary parenteral nutrition and discontinuous administrations of omeprazole, piperacillin/tazobactam and fluconazole), the overall number of particles over the 6-h infusion period was 8256 [5013; 15,044]. The collected values for the number of particles ≥ 10 and 25 μm were 281 [118; 526] and 19 [7; 96] respectively. Our results showed that discontinuous administrations of drugs led to disturbances in particulate contamination. This work indicates the amount of particulate matter potentially administered to critically ill adult patients. Particulate contamination appears lower than previous measurements performed during multidrug IV therapies in children