Cerebral Blood Flow and Oxygen Delivery in Aneurysmal Subarachnoid Hemorrhage: Relation to Neurointensive Care Targets.

BACKGROUND: The primary aim was to determine to what extent continuously monitored neurointensive care unit (neuro-ICU) targets predict cerebral blood flow (CBF) and delivery of oxygen (CDO2) after aneurysmal subarachnoid hemorrhage. The secondary aim was to determine whether CBF and CDO2 were associated with clinical outcome. METHODS: In this observational study, patients with aneurysmal subarachnoid hemorrhage treated at the neuro-ICU in Uppsala, Sweden, from 2012 to 2020 with at least one xenon-enhanced computed tomography (Xe-CT) obtained within the first 14 days post ictus were included. CBF was measured with the Xe-CT and CDO2 was calculated based on CBF and arterial oxygen content. Regional cerebral hypoperfusion was defined as CBF < 20 mL/100 g/min, and poor CDO2 was defined as CDO2 < 3.8 mL O2/100 g/min. Neuro-ICU variables including intracranial pressure (ICP), pressure reactivity index, cerebral perfusion pressure (CPP), optimal CPP, and body temperature were assessed in association with the Xe-CT. The acute phase was divided into early phase (day 1-3) and vasospasm phase (day 4-14). RESULTS: Of 148 patients, 27 had underwent a Xe-CT only in the early phase, 74 only in the vasospasm phase, and 47 patients in both phases. The patients exhibited cerebral hypoperfusion and poor CDO2 for medians of 15% and 30%, respectively, of the cortical brain areas in each patient. In multiple regressions, higher body temperature was associated with higher CBF and CDO2 in the early phase. In a similar regression for the vasospasm phase, younger age and longer pulse transit time (lower peripheral resistance) correlated with higher CBF and CDO2, whereas lower hematocrit only correlated with higher CBF but not with CDO2. ICP, CPP, and pressure reactivity index exhibited no independent association with CBF and CDO2. R2 of these regressions were below 0.3. Lower CBF and CDO2 in the early phase correlated with poor outcome, but this only held true for CDO2 in multiple regressions. CONCLUSIONS: Systemic and cerebral physiological variables exhibited a modest association with CBF and CDO2. Still, cerebral hypoperfusion and low CDO2 were common and low CDO2 was associated with poor outcome. Xe-CT imaging could be useful to help detect secondary brain injury not evident by high ICP and low CPP.

Telemetric intracranial pressure monitoring: a noninvasive method to follow up children with complex craniosynostoses. A case report.

INTRODUCTION: There are no reliable noninvasive methods of monitoring ICP. Most assessments are made by indirect measures and are difficult to follow over time. Invasive studies can be used but up until now have required in-hospital transcutaneous measurements. Accurate ICP recordings over longer periods of time can be very valuable in timing different surgical procedures in syndromal cases. This case shows that telemetric ICP monitoring can be used for long-term follow-up in patients that may need repeated surgeries related to their craniosynostosis condition. CASE REPORT: In this report, the telemetric ICP probe (Raumedic Neurovent-P-tel) was implanted before surgery and was used for repeated "noninvasive" ICP recordings pre- and postoperatively in a patient with craniosynostosis. The patient was an eight-year-old girl with pansynostosis with only the right lambdoid suture open. A telemetric ICP probe was implanted the day before cranial vault remodeling and the ICP was monitored pre- and postoperatively. The ICP was above 15 mmHg 72.2 % of the monitoring time before surgery, and the amplitude of the curve was greater than normal suggesting impaired compliance. Direct postoperative ICP was normal, and the amplitude was lower. The ICP was then monitored both in out-patient clinic and in four longer hospital stays. Both the values and the curves were analyzed, and the time with ICP above 15 mmHg decreased over time, and the waveform amplitude of the curves improved. CONCLUSION: This "noninvasive" way of recording ICP is a feasible and helpful tool in decision-making and intervening in patients with craniosynostosis.