mal pulmonary function at the time of brain death may have declines in functioning, and only 15% to 20% of these patients' lungs are subsequently suitable for transplantation. 1-3 This may result from the pulmonary damage associated with brain injury 4 or the iatrogenic effects of mechanical ventilation. 5,6 There is evidence in various settings demonstrating that a lung protective strategy is beneficial. In patients with acute lung injury, ventilation See also pp 2592 and 2643 and Patient Page.

The current investigators applied nonlinear mathematical tools to HR and RR time series during weaning trials and compared these analyses between successfully weaned patients and those who failed weaning. They found that patients who had successful weaning had a more complex pattern of HR and RR patterns than those who failed. They proposed a model to predict weaning that was more accurate for their group of patients than the conventional model that included rapid shallow breathing index and airway occlusion pressure at 0.1 second.Although the results are very interesting, they cannot be endorsed for 2 main reasons. First, they are very complex to perform and are not fully understood by physicians. In addition, the current results can only serve as a hypothesis for future studies. Despite these reservations, it is important to realize that the future of complex signal analysis is drawing near and that we, the clinical community, have to start to embrace this complex mathematical field if we wish to understand the information we derive from our physiologic monitoring devices.

BackgroundNeuroinflammation has been proposed as a possible mechanism of brain damage after traumatic brain injury (TBI), but no consensus has been reached on the most relevant molecules. Furthermore, secondary insults occurring after TBI contribute to worsen neurological outcome in addition to the primary injury. We hypothesized that after TBI, a specific pattern of cytokines is related to secondary insults and outcome.MethodsA prospective observational clinical study was performed. Secondary insults by computerized multimodality monitoring system and systemic value of different cytokines were collected and analysed in the first week after intensive care unit admission. Neurological outcome was assessed at 6 months (GOSe). Multivariate projection technique was applied to analyse major sources of variation and collinearity within the cytokines dataset without a priori selecting potential relevant molecules.ResultsTwenty-nine severe traumatic brain injury patients undergoing intracranial pressure monitoring were studied. In this pilot study, we demonstrated that after TBI, patients who suffered of prolonged and severe secondary brain damage are characterised by a specific pattern of cytokines. Patients evolving to brain death exhibited higher levels of inflammatory mediators compared to both patients with favorable and unfavorable neurological outcome at 6 months. Raised ICP and low cerebral perfusion pressure occurred in 21 % of good monitoring time. Furthermore, the principal components selected by multivariate projection technique were powerful predictors of neurological outcome.ConclusionsThe multivariate projection method represents a valuable methodology to study neuroinflammation pattern occurring after secondary brain damage in severe TBI patients, overcoming multiple putative interactions between mediators and avoiding any subjective selection of relevant molecules.

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