Abstract
BackgroundResection of cerebral arteriovenous malformations (AVM) is technically demanding because of size, eloquent location or diffuse nidus. Controlled arterial hypotension (CAH) could facilitate haemostasis. We performed a study to characterize the duration and degree of CAH and to investigate its association with blood loss and outcome.MethodsWe retrospectively analysed intraoperative arterial blood pressure of 56 patients that underwent AVM-resection performed by the same neurosurgeon between 2003 and 2012. Degree of CAH, AVM size, grading and neurological outcome were studied. Patients were divided into two groups, depending on whether CAH was performed (hypotension group) or not (control group).ResultsThe hypotension group consisted of 28 patients, which presented with riskier to treat AVMs and a higher Spetzler-Martin grading. CAH was achieved by application of urapidil, increasing anaesthetic depth or a combination thereof. Systolic and mean arterial blood pressure were lowered to 82 ± 7 and 57 ± 7 mmHg, respectively, for a median duration of 58 min [25% percentile: 26 min.; 75% percentile: 107 min]. In the hypotension group, duration of surgery (4.4 ± 1.3 h) was significantly (p < 0.001) longer, and median blood loss (500 ml) was significantly (p = 0.002) higher than in the control group (3.3 ± 0.9 h and 200 ml, respectively). No case fatalities occurred. CAH was associated with a higher amount of postoperative neurological deficits.ConclusionsWhether CAH caused neurological deficits or prevented worse outcomes could be clarified by a prospective randomised study, which is regarded as ethically problematic in the context of bleeding. CAH should only be used after strict indication and should be applied as mild and short as possible.
Highlights
Resection of cerebral arteriovenous malformations (AVM) is technically demanding because of size, eloquent location or diffuse nidus
Anaesthesia affects cerebral autoregulation depending on the hypnotic drugs used: It is maintained during propofol anaesthesia but impaired when using volatile anaesthetics in a dose depending fashion: While cerebral autoregulation is preserved during concentrations up to 1 MAC, it is impaired at higher concentrations (> 1.5 MAC) [32]
Patients of the hypotension group presented with a significant (p = 0.025) lower modified Rankin scale grade on admission and tended to be Control group p-value
Summary
Resection of cerebral arteriovenous malformations (AVM) is technically demanding because of size, eloquent location or diffuse nidus. Some vessels cannot be occluded immediately which could result in profound blood loss. In these instances, a lowering of perfusion pressure will reduce blood loss and allows the surgeon a better view (and control) of the bleeding source. As a consequence, controlled arterial hypotension (CAH), defined as a lowering of arterial blood pressure (ABP) by pharmacologic measures, is an established procedure [15] in ophthalmic, ear, endoscopic or vascular surgery. The pathophysiology is at least partially different, since cerebral autoregulation will maintain cerebral blood flow (CBF) despite lowering of arterial blood pressure. If ABP drops below the lower threshold of cerebral autoregulation, CBF will decrease and blood loss through an injured cerebral vessel will be reduced. Anaesthesia affects cerebral autoregulation depending on the hypnotic drugs used: It is maintained during propofol anaesthesia but impaired when using volatile anaesthetics in a dose depending fashion: While cerebral autoregulation is preserved during concentrations up to 1 MAC, it is impaired at higher concentrations (> 1.5 MAC) [32]
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