Glucose and Lactate Concentrations in Cerebrospinal Fluid After Traumatic Brain Injury.

BACKGROUND: Studies in which brain metabolism has been monitored using microdialysis have indicated decreases in cerebral glucose concentration and increases in lactate concentration in patients with traumatic brain injury (TBI). However, few data are available on glucose and lactate concentrations in the cerebrospinal fluid (CSF) of TBI patients. This study investigates the relationship between CSF glucose and lactate concentrations and outcomes after TBI. METHODS: Consecutive adult (>18 y) TBI patients were admitted to our 35-bed medicosurgical between 2011 and 2014 and were included in the study if they met the following inclusion criteria: presence of an external ventricular drain (EVD) for intracranial pressure monitoring, daily analysis of CSF glucose and lactate concentrations for 4 consecutive days, and concomitant measurements of blood glucose/lactate concentrations. Neurological outcome was assessed at 3 months using the extended Glasgow Outcome Scale (GOS), and unfavorable outcome defined as a GOS 1 to 4. RESULTS: Of 151 TBI patients who had an EVD, 56 met the inclusion criteria. Most EVDs were placed on the day of intensive care unit admission, and maintained for 10 (interquartile range: 6 to 14) days. On day 1, there was a weak but significant correlation between blood and CSF glucose concentrations (R=0.07, P=0.04), and a greater correlation between blood and CSF lactate (R=0.32, P<0.001). In multivariable analysis, day 1 CSF glucose/lactate ratio was independently associated with mortality (odds ratio: 0.22, 95% confidence interval: 0.08-0.61; P=0.003), and day 1 CSF lactate concentration with unfavorable outcome (odds ratio: 4.86; 95% confidence interval: 1.86-12.67; P=0.001). CONCLUSIONS: Low CSF glucose/lactate ratio is observed in nonsurvivors after severe TBI and may have prognostic value.

Postoperative pulmonary dysfunction and mechanical ventilation in cardiac surgery.

Postoperative pulmonary dysfunction (PPD) is a frequent and significant complication after cardiac surgery. It contributes to morbidity and mortality and increases hospitalization stay and its associated costs. Its pathogenesis is not clear but it seems to be related to the development of a systemic inflammatory response with a subsequent pulmonary inflammation. Many factors have been described to contribute to this inflammatory response, including surgical procedure with sternotomy incision, effects of general anesthesia, topical cooling, and extracorporeal circulation (ECC) and mechanical ventilation (VM). Protective ventilation strategies can reduce the incidence of atelectasis (which still remains one of the principal causes of PDD) and pulmonary infections in surgical patients. In this way, the open lung approach (OLA), a protective ventilation strategy, has demonstrated attenuating the inflammatory response and improving gas exchange parameters and postoperative pulmonary functions with a better residual functional capacity (FRC) when compared with a conventional ventilatory strategy. Additionally, maintaining low frequency ventilation during ECC was shown to decrease the incidence of PDD after cardiac surgery, preserving lung function.