Background and Purpose-Arginine vasopressin V 1 receptors have been suggested to be involved in the pathophysiology of acute brain injury. Therefore, we aimed to determine the role of arginine vasopressin V 1 receptors after experimental subarachnoid hemorrhage (SAH). Methods-Sprague-Dawley rats subjected to SAH by endovascular puncture received either vehicle or a V 1 receptor antagonist intravenously from 1 minute before until 3 hours after SAH. Intracranial pressure, cerebral blood flow, and mean arterial blood pressure were monitored until 60 minutes after SAH. Brain water content was quantified 24 hours after SAH and neurological function and mortality were assessed daily for 7 days after hemorrhage. Results-In control rats, SAH induced high intracranial pressure, a brief increase in plasma arginine vasopressin, a subsequent increase in systemic blood pressure (Cushing response), a high rebleeding rate (30%), severe neurological deficits, and a 7-day mortality rate of 50%. V 1 receptor antagonist-treated animals exhibited a far less pronounced Cushing response, a less severe increase of intracranial pressure, did not exhibit rebleedings, had less severe brain edema formation and neurological deficits, and a mortality rate of only 20% (all PϽ0.05 versus vehicle). Conclusions-Inhibition of arginine vasopressin V 1a receptors reduces the severity of SAH and prevents rebleedings by blunting the posthemorrhagic hypertonic response (Cushing reflex), thereby reducing mortality and secondary brain damage after experimental SAH. Because the severity of the initial bleeding and rebleedings are major factors contributing to an unfavorable outcome after SAH, inhibition of V 1a receptors may represent a novel strategy to treat SAH. (Stroke. 2012;43:227-232.)

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Integrity of AR has a similar role for outcome after TBI in the paediatric population as in adults. The amount of time spent with deranged AR seems to be associated with outcome; a factor especially critical for infant patients. The results of this preliminary study need to be validated in the future.

BackgroundAnesthesia is indispensable for in vivo research but has the intrinsic potential to alter study results. The aim of the current study was to investigate the impact of three common anesthesia protocols on physiological parameters and outcome following the most common experimental model for subarachnoid hemorrhage (SAH), endovascular perforation.MethodsSprague-Dawley rats (n = 38) were randomly assigned to (1) chloral hydrate, (2) isoflurane or (3) midazolam/medetomidine/fentanyl (MMF) anesthesia. Arterial blood gases, intracranial pressure (ICP), mean arterial blood pressure (MAP), cerebral perfusion pressure (CPP), and regional cerebral blood flow (rCBF) were monitored before and for 3 hours after SAH. Brain water content, mortality and rate of secondary bleeding were also evaluated.ResultsUnder baseline conditions isoflurane anesthesia resulted in deterioration of respiratory parameters (arterial pCO2 and pO2) and increased brain water content. After SAH, isoflurane and chloral hydrate were associated with reduced MAP, incomplete recovery of post-hemorrhagic rCBF (23 ± 13% and 87 ± 18% of baseline, respectively) and a high anesthesia-related mortality (17 and 50%, respectively). Anesthesia with MMF provided stable hemodynamics (MAP between 100-110 mmHg), high post-hemorrhagic rCBF values, and a high rate of re-bleedings (> 50%), a phenomenon often observed after SAH in humans.ConclusionBased on these findings we recommend anesthesia with MMF for the endovascular perforation model of SAH.

The general practice of draining CSF and monitoring ICP via a (usually open) EVD plus frequently performed catheter closure for ICP reading is feasible for assessment of overall ICP trends. However, it does have clinically relevant drawbacks, namely, a significant amount of undetected increases in ICP above thresholds, and continuous assessment of cerebrovascular autoregulation is less reliable. In conclusion, all patients who need CSF drainage plus ICP monitoring due to the severity of their brain insult need either an EVD with integrated ICP probe or an EVD line plus a separate ICP probe.

There is significant uncertainty regarding the management of perioperative bridging of anticoagulation and APT in neurosurgery because of a lack of prospective and limited retrospective data.

The integrity of AR seems to play the same fundamental role after TBI in the pediatric population as in adults and should be determined routinely. It carries an important prognostic value. PRx seems to be an ideal candidate parameter to guide treatment in the sense of optimizing CPP, aiming at improvement of cerebrovascular autoregulation (CPPopt concept).

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