[Management of organ donation for patients with severe coma due to cerebrovascular stroke]. / Place du don d'organes chez les patients en coma grave à la suite d'un accident vasculaire cérébral.

INTRODUCTION: Organ procurement practices are tending towards the use of older or more borderline donors. In the current context of steadily decreasing availability of traumatic donors, stroke victims make up the majority of donors. In France, where organ procurement activity has stabilized following a period of growth, the possibility of organ donation after a cerebral stroke is variable and uncertain. STATE OF THE ART: Among potential donors--severe coma patients beyond therapeutic possibilities--those who are stroke victims are also those for whom emergency units often initiate the support withdrawal process early, before brain death. Yet the time to the final diagnosis of brain death is also the time necessary for intensive care before organ procurement. Several teams with expert experience in dealing with relatives in these circumstances have demonstrated the steps of the process. PERSPECTIVES: Potential donors can be admitted to intensive care units with the exclusive aim of organ removal. This strategy can be accepted only if the organ donation has a reasonable chance of success. The probability of brain death must therefore be likely and no contraindications found. The key element is open and frank communication with relatives about the severity of brain injury and the lack of therapeutic alternatives. With the relatives, it is recommended to separate the discussion of withdrawal from the question of possible opposition to organ donation. CONCLUSIONS: This approach allows both support for end-of-life patients, and fulfillment of their wishes with regards to organ donation. It enables case-by-case decision-making, after relatives have agreed on transfer to the intensive care unit for organ removal. Thus, each hospital should institute a fully cooperative care procedure where all therapeutic possibilities are evaluated in order to enable the most appropriate therapeutic approach, and, if applicable, organ procurement.

Significance of the changes in the respiratory system pressure-volume curve during acute lung injury in rats.

UNLABELLED: The hypothesis that the changes in the respiratory system pressure- volume (PV) curve during pulmonary edema mainly reflect distal airway obstruction was investigated in rats. Normal rats had a well-defined upper inflection point (UIP) at low airway pressure. Airway occlusion by liquid instillation decreased compliance (Crs) and the volume (Vuip) of the UIP, and increased end-inspiratory pressure. The same changes were observed during the progression of edema produced by high volume ventilation (HV). Changes in Vuip and in Crs produced by HV were correlated with edema severity in normal rats or rats with lungs preinjured with alpha-naphthylthiourea. Vuip and Crs changes were proportional, reflecting compression of the PV curve on the volume axis and suggesting reduction of the amount of ventilatable lung at low airway pressure. In keeping with this explanation, the lower Vuip and Crs were before HV, the more severe HV-induced edema was in alpha-naphthylthiourea-injected rats. When edema was profuse, PV curves displayed a marked lower inflection point (LIP), the UIP at low pressure disappeared but another was seen at high volume above the LIP, and the correlation between Vuip changes and edema severity was lost. These observations may have clinical relevance in the context of the "open lung" strategy. KEYWORDS: ventilator-induced lung injury; respiratory mechanics; acute respiratory distress syndrome

Accuracy of delayed cultures of plugged telescoping catheter samples for diagnosing bacterial pneumonia.

OBJECTIVE: It is not always feasible to culture immediately bacteriologic samples of protected pulmonary specimens on a 24-hr basis before starting antibiotic treatment. We have evaluated the effect of delaying the culture of immediate plugged telescoping catheter (PTC) samples performed before starting antibiotherapy. DESIGN: Prospective paired comparisons study. SETTING: Intensive care unit in a university hospital. PATIENTS: Ninety-nine PTCs were performed on 68 intensive care unit patients suspected of nosocomial or community- acquired bacterial pneumonia. INTERVENTION: PTC samples were divided into two aliquots: one for immediate (H0) analysis and one for storage at 4 degrees C (H24) for 24 hrs before being cultured. MEASUREMENTS AND MAIN RESULTS: The results from these delayed cultures (H24) were compared with those from immediate ones (H0). All negative H0 samples (n = 59) were also negative at H24. Forty PTCs yielded one or more microorganisms, with a total of 69 microorganisms in one or both samples. H0 and H24 cultures were concordant in 119 of 128 (97.9%) cases (kappa coefficient value 0.79) with a threshold of 103 colony-forming units (cfu)/mL. Agreement between paired cultures was very good. The bias calculated as the mean difference between paired culture results was 0.128 +/- 1.024 (Deltalog). Concordance using the 103 cfu/mL threshold (102/107 cases, kappa coefficient value 0.82) and agreement were enhanced (0.067 +/- 0.645) when possible contaminants were excluded (n = 21). CONCLUSIONS: Storing PTC specimens for 24 hrs at 4 degrees C is an acceptable alternative when culturing cannot be performed immediately. This allows starting antibiotic treatment without any delay.

Alveolar permeability and liquid absorption during partial liquid ventilation of rats with perflubron.

We examined the effect of instilled perflubron (LiquiVent) on the transport properties of alveolar epithelium in anesthetized rats. Krebs-Ringer bicarbonate (1 to 4 ml) containing (125)I-albumin, [(3)H]mannitol and [(14)C] sucrose was instilled into airspaces either alone (n = 29), or with 1 (n = 21) or 2 (n = 12) ml perflubron and sampled 30 min later. Absorption was deduced from the changes in (125)I-albumin activity per unit volume in the airspace instillate, and changes in [(3)H]mannitol and [(14)C]sucrose activity per unit volume were used to evaluate the passive permeability of the alveolar-airway barrier. The rate of Ringer absorption depended on the volume instilled [0.38 (ml/h)/ml Ringer]. Perflubron (1 or 2 ml) increased Ringer absorption by 0.26 (p < 0. 001) and 0.19 ml/h (p < 0.05), respectively. However, 2 ml perflubron increased absorption less than did the same additional volume of Ringer (p < 0.001). The passive permeability of the alveolar-airway barrier increased exponentially with instilled Ringer volume. Sucrose/mannitol size selectivity was lost when Ringer volume was > 2 ml and albumin leaked from airspaces when it was 4 ml. Instillation of 2 ml perflubron prevented this increase in permeability, but 1 ml did not. No albumin leaked with perflubron even when the total volume of liquid in airspaces (Ringer + perflubron) was > 4 ml. These results suggest that perflubron can be beneficial in pulmonary edema by redistributing the alveolar liquid over a larger surface area, thus accelerating resorption. In addition, larger doses of perflubron may better preserve epithelial permeability during alveolar flooding.

Hyperinflation-induced lung injury during alveolar flooding in rats: effect of perfluorocarbon instillation.

Mechanical nonuniformity of diseased lungs may predispose them to ventilator-induced lung injury (VILI) by overinflation of the more compliant, aerated zones. Perfluorocarbon (PFC) may reduce this nonuniformity by suppressing air-liquid interfaces. Saline (6.8 ml/kg) was instilled into the trachea to mimic alveolar edema and reduce aerated lung volume before mechanical ventilation (6, 16, 24, or 32 ml/kg tidal volume [VT]) for 10 min in rats. Flooding significantly aggravated VILI when VT was 24 or 32 ml/kg, with an increase in the distribution space of albumin in lungs (p < 0.001). Tracheal instillation of a low dose (3.3 ml/kg) of PFC (Liquivent) either before or after the instillation of saline considerably reduced VILI (p < 0.001). Saline instillation raised the lower inflection point of the respiratory system pressure-volume curve to values as high as 25 cm H2O, and produced a significant increase in end-inspiratory pressure (from 38 +/- 2.0 cm H2O to 61 +/- 2.4 cm H2O, for a VT of 32 ml/kg; p < 0.001). PFC significantly reduced the pressure at the lower inflection point and normalized end-inspiratory pressure. These decreases were correlated with a smaller albumin distribution space (p < 0.001). Animals in which PFC instillation failed to reduce the albumin space had pressures similar to those of animals given saline alone. In conclusion, the effectiveness of PFC instillation in reducing VILI may be predicted by the shape of the pressure-volume curve. These findings may help in designing safer clinical studies of mechanical ventilation and in reducing the cost of partial liquid ventilation by reducing doses of PFC.