1133 The Recovery of Sleep Oscillations in Acute to Chronic Traumatic Brain Injury

Introduction

Slow waves and spindles are essential oscillations occurring during NREM sleep that may be disrupted by moderate to severe traumatic brain injury (TBI). We investigated these oscillations in the acute and chronic trauma stage.

Methods

Four groups were tested with whole-night polysomnography: hospitalized patients with acute TBI (n=10, 29.7±13.8y) or severe orthopedic injuries (n=15, 39.9±17.1y), chronic TBI including 9 returning from the acute TBI group (n=43, 31.9±13.5y), and healthy controls (n=36, 30.5±12.7y). Characteristics for slow waves (density, amplitude, slope, frequency, duration) and spindles (density, amplitude, frequency, duration) were quantified over N2 and N3 sleep for the first three sleep cycles, and groups were compared using one-way ANOVAs.

Results

One-way ANOVAs showed group effects only for slow wave density (F=4.11 to 6.04, p=0.009 to 0.0008)) and spindle density (F=3.3 to 8.8, p=0.02 to 0.00003). These effects were present for the 2nd and 3rd sleep cycles, but not the 1st. More specifically, slow wave density in acute TBI was higher than in controls, and returned to normal levels in the chronic stage. Conversely, spindle density in acute TBI was lower than in controls and returned to normal levels in the chronic stage. No group difference was observed for the orthopedic group.

Conclusion

Our results suggest that immediately after a severely disruptive event such as a TBI, the brain needs additional deeper sleep to recover, resulting in more slow waves but also in less spindles. These changes are only present in the 2nd and 3rd sleep cycles, reflecting an absence of the expected dissipation of slow waves, which may suggest increased homeostatic sleep pressure due to the brain injury. Limits to interpretation include the hospital environment and medication, but the absence of changes in the orthopedic group under similar conditions emphasizes the effect of the brain injury itself.

Support

Canadian Institutes of Health Research (CIHR) and Fonds de Recherche Québec-Santé (FRQS)

Time course of cytokine release and complement activation after implantation of the HeartMate left ventricular assist device

Pro-inflammatory mediators, including interleukin-6 (IL-6), IL-8, and complement C3a, are released after cardiac surgery as part of the inflammatory response related to blood-biomaterial interaction in the cardiopulmonary bypass circuit. Post operative time course data for these mediators are not fully defined in patients receiving left ventricular assist device (LVAD) support. The authors performed enzyme linked immunosorbent assays for concentrations of IL-6, IL-8, and C3a in plasma in six HeartMate LVAD recipients at the following times: pre operatively; 4, 8, 16, 24, 36, and 48 hr post operatively; daily through the first week; and weekly thereafter for 6 weeks. All patients survived without major complications during the study. Pre operative concentrations of IL-6 and C3a in plasma were significantly increased compared with age matched controls. Post operatively, the concentrations of IL-6 and IL-8 in plasma took longer to return to baseline values after insertion of the LVAD than the trends reported in the literature after routine cardiopulmonary bypass alone. Concentrations of IL-6 and complement C3a continued to decrease to lower than baseline post operatively, reaching statistical significance after 6 weeks of LVAD support. The authors conclude that the presence of the HeartMate LVAD delays the return of pro-inflammatory mediator concentrations back to baseline values compared with routine cardiopulmonary bypass alone, but the device does not appear to be an ongoing source of cytokine release or complement activation.