Neurointensive care of traumatic brain injury in the elderly-age-specific secondary insult levels and optimal physiological levels to target need to be defined

Cerebrovascular reactivity (PRx) and optimal cerebral perfusion pressure in elderly with traumatic brain injury

PURPOSE

Cerebral perfusion pressure (CPP) guidance by cerebral pressure autoregulation (CPA) status according to PRx (correlation mean arterial blood pressure (MAP) and intracranial pressure (ICP)) and optimal CPP (CPPopt = CPP with lowest PRx) is promising but little is known regarding this approach in elderly. The aim was to analyze PRx and CPPopt in elderly TBI patients.

METHODS

A total of 129 old (≥ 65 years) and 342 young (16-64 years) patients were studied using monitoring data for MAP and ICP. CPP, PRx, CPPopt, and ΔCPPopt (difference between actual CPP and CPPopt) were calculated. Logistic regression analyses with PRx and ΔCPPopt as explanatory variables for outcome. The combined effects of PRx/CPP and PRx/ΔCPPopt on outcome were visualized as heatmaps.

RESULTS

The elderly had higher PRx (worse CPA), higher CPPopt, and different temporal patterns. High PRx influenced outcome negatively in the elderly but less so than in younger patients. CPP close to CPPopt correlated to favorable outcome in younger, in contrast to elderly patients. Heatmap interaction analysis of PRx/ΔCPPopt in the elderly showed that the region for favorable outcome was centered around PRx 0 and ranging between both functioning and impaired CPA (PRx range - 0.5-0.5), and the center of ΔCPPopt was - 10 (range - 20-0), while in younger the center of PRx was around - 0.5 and ΔCPPopt closer to zero.

CONCLUSIONS

The elderly exhibit higher PRx and CPPopt. High PRx influences outcome negatively in the elderly but less than in younger patients. The elderly do not show better outcome when CPP is close to CPPopt in contrast to younger patients.

ICP, CPP, and PRx in traumatic brain injury and aneurysmal subarachnoid hemorrhage: association of insult intensity and duration with clinical outcome

OBJECTIVE

The primary aim of this study was to determine the combined effect of insult intensity and duration of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and pressure reactivity index (PRx) on outcome measured with the Glasgow Outcome Scale-Extended (GOS-E) in patients with traumatic brain injury (TBI) or aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

This observational study included all TBI and aSAH patients treated in the neurointensive care unit in Uppsala, Sweden, 2008-2018, with at least 24 hours of ICP monitoring during the first 10 days following injury and available long-term clinical outcome data. ICP, CPP, and PRx insults were visualized as 2D plots to highlight the effects of both insult intensity and duration on patient outcome.

RESULTS

Of 950 included patients, 436 were TBI and 514 aSAH patients. The TBI patients were younger, more often male, and exhibited worse neurological status at admission, but recovered more favorably than the aSAH patients. There was a transition from good to poor outcome with ICP above 15-20 mm Hg in both TBI and aSAH. The two diagnoses had opposite CPP patterns. In TBI patients, CPP episodes at or below 80 mm Hg were generally favorable, whereas CPP episodes above 80 mm Hg were favorable in the aSAH patients. In the TBI patients there was a transition from good to poor outcome when PRx exceeded zero, but no evident transition was found in the aSAH cohort.

CONCLUSIONS

The insult intensity and duration plots formulated in this study illustrate the similarities and differences between TBI and aSAH patients. In particular, aSAH patients may benefit from much higher CPP targets than TBI patients.