Intraarterial Nimodipine Versus Induced Hypertension for Delayed Cerebral Ischemia: A Modified Treatment Protocol.

BACKGROUND: Rescue treatment for delayed cerebral ischemia (DCI) after subarachnoid hemorrhage can include induced hypertension (iHTN) and, in refractory cases, endovascular approaches, of which selective, continuous intraarterial nimodipine (IAN) is one variant. The combination of iHTN and IAN can dramatically increase vasopressor demand. In case of unsustainable doses, iHTN is often prioritized over IAN. However, evidence in this regard is largely lacking. We investigated the effects of a classical (iHTN+IAN) and modified (IANonly) treatment protocol for refractory DCI in an observational study. METHODS: Rescue treatment for DCI was initiated with iHTN (target >180 mm Hg systolic) and escalated to IAN in refractory cases. Until July 2018, both iHTN and IAN were offered in cases refractory to iHTN alone. After protocol modification, iHTN target was preemptively lowered to >120 mm Hg when IAN was initiated (IANonly). Primary outcome was noradrenaline demand. Secondary outcomes included noradrenaline-associated complications, brain tissue oxygenation, DCI-related infarction and favorable 6-month outcome (Glasgow Outcome Scale 4-5). RESULTS: N=29 and n=20 patients were treated according to the classical and modified protocol, respectively. Protocol modification resulted in a significant reduction of noradrenaline demand (iHTN+IAN 0.70±0.54 µg/kg per minute and IANonly 0.26±0.20 µg/kg per minute, P<0.0001) and minor complications (15.0% versus 48.3%, unadjusted odds ratio, 0.19 [95% CI, 0.05-0.79]; P<0.05) with comparable rates of major complications (20.0% versus 20.7%, odds ratio, 0.96 [0.23-3.95]; P=0.95). Incidence of DCI-related infarction (45.0% versus 41.1%, odds ratio, 1.16 [0.37-3.66]; P=0.80) and favorable clinical outcome (55.6% versus 40.0%, odds ratio, 1.88 [0.55-6.39]; P=0.32) were similar. Brain tissue oxygenation was significantly higher with IANonly (26.6±12.8, 39.6±15.4 mm Hg; P<0.01). CONCLUSIONS: Assuming the potential of iHTN to be exhausted in case of refractory hypoperfusion, additional IAN may serve as a last-resort measure to bridge hypoperfusion in the DCI phase. With close monitoring, preemptive lowering of pressure target after induction of IAN may be a safe alternative to alleviate total noradrenaline load and potentially reduce complication rate.

Systemic and Cerebral Concentration of Nimodipine During Established and Experimental Vasospasm Treatment.

BACKGROUND: Oral nimodipine is an established prophylactic agent for cerebral vasospasm after subarachnoid hemorrhage (SAH). In highly selected cases, intra-arterial (IA) or intravenous (IV) application of nimodipine may be considered; however, the optimum dosage and modality of application remain a matter of debate. The purpose of this investigation is analysis of nimodipine concentration in serum, cerebrospinal fluid, and cerebral microdialysate in the context of currently effective dose and route of application (oral, IA, IV). METHODS: We prospectively collected 156 samples from 37 patients treated for aneurysmal SAH from May 2014 to July 2015. Treatment groups were stratified according to modality of application and low-dose or high-dose treatment. At time of sampling, current dose and modality of application effectively sustained cerebral perfusion as documented by common diagnostics. Samples were analyzed for nimodipine concentration via high-performance liquid chromatography and tandem mass spectrometry. RESULTS: In most cases (94.3%), nimodipine remained below the limit of quantification (0.5 ng/mL) within the brain (microdialysis, cerebrospinal fluid), even during targeted, local application (IA nimodipine). The median serum concentration for all treatment groups was 17.3 ng/mL. Modality of application (oral, IA, IV) was not associated with significant differences in serum concentrations (P = 0.712), even after stratification for dosage (P = 0.371), implying a comparable systemic distribution, if not efficacy. CONCLUSIONS: Nimodipine does not accumulate sufficiently within the target organ for treatment monitoring. Comparable systemic concentrations can be observed irrespective of application modality and dosing. Future studies will clarify the role of efficacy-driven treatment algorithms, in which lowest dose and least invasive mode of application still effective should be identified.