Because oxygen free radicals have been implicated in the endothelial cell damage and in the myocardial depression occurring during severe sepsis, we investigated whether N-acetyl-L-cysteine (NAC) could influence the oxygen extraction capabilities during an acute reduction in blood flow induced by cardiac tamponade after endotoxin challenge. Sixteen anesthetized, saline-infused, and ventilated dogs received Escherichia coli endotoxin (2 mg/kg) 30 min before tamponade was induced by repeated bolus injections of warm saline into the pericardial space. Thirty minutes before endotoxin administration, nine dogs received NAC (150 mg/kg, followed by a 20 mg.kg-1.h-1 infusion); the other seven dogs served as a control group. The NAC group maintained higher cardiac index, oxygen delivery (DO2), and left ventricular stroke work index, but lower systemic and pulmonary vascular resistance, than the control group. The oxygen uptake (VO2) levels at critical DO2 (DO2crit) were identical in the two groups. However, DO2crit was significantly lower in the NAC than in the control group (8.1 +/- 1.7 vs. 10.8 +/- 1.8 ml.kg-1.min-1, P < 0.01). Critical oxygen extraction ratio and the slope of the VO2-to-DO2-dependent line were higher in the NAC than in the control group (72 +/- 14 vs. 53 +/- 15% and 0.80 vs. 0.56, respectively; both P < 0.05). The peak lactate and the maximal tumor necrosis factor (TNF) levels were lower in the NAC than in the control group (5.2 +/- 0.4 vs. 7.6 +/- 0.4 mM, and 0.14 +/- 0.03 vs. 1.21 +/- 0.58 ng/ml, respectively; both P < 0.01). NAC significantly increased glutathione peroxidase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Little data is available on this topic. Infused particles may induce organ failure, in particular pulmonary toxicity and SIRS. Further studies are needed to establish a link between the level of exposure to drug incompatibilities and clinical implication.
BackgroundIn 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.MethodsThe 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).ResultsFor 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.ConclusionsThis 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.
Comparison of the abdominal muscle response to CO2 rebreathing in rapid-eye-movement (REM) and non-REM (NREM) sleep was performed in healthy premature infants near full term. Eight subjects were studied at a postconceptional age of 40 +/- 1.6 (SD) wk (range 38-43 wk) during spontaneous sleep. Sleep stages were defined on the basis of electrophysiological and behavioral criteria, and diaphragmatic and abdominal muscle electromyographic activity was recorded by cutaneous electrodes. The responses to CO2 were measured by a modified Read rebreathing technique. The minute ventilation and diaphragmatic and abdominal muscle electromyographic activities were calculated and plotted against end-tidal CO2 partial pressure. Both the ventilatory and diaphragmatic muscle responses to CO2 decreased from NREM to REM sleep (P less than 0.05). Abdominal muscles were forcefully recruited in response to CO2 rebreathing during NREM sleep. In REM sleep, abdominal muscle response to CO2 was virtually absent or decreased compared with NREM sleep (P less than 0.05). We conclude that 1) the abdominal muscles are recruited during NREM sleep in response to CO2 rebreathing in healthy premature infants near full term and 2) the abdominal muscle recruitment is inhibited during REM sleep compared with NREM sleep, and this REM sleep-related inhibition probably contributes to the decrease in the ventilatory response to CO2 rebreathing in REM sleep.
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