Effect of Vasoactive Therapy on Cerebral Circulation

Optimizing drug therapy in the surgical intensive care unit

This article provides a review of commonly prescribed medications in the surgical ICU, focusing on sedatives, antipsychotics, neuromuscular blocking agents, cardiovascular agents, anticoagulants, and antibiotics. A brief overview of pharmacology is followed by practical considerations to aid prescribers in selecting the best therapy within a given category of drugs to optimize patient outcomes.

Current and future treatment considerations in the management of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a type of hemorrhagic stroke that can cause significant morbidity and mortality. Although guidelines have been published to help direct the care of these patients, there is insufficient quality literature regarding the medical and pharmacological management of patients with aSAH. Treatment is divided into 3 categories: supportive therapy, prevention of complications, and treatment of complications. There are numerous pharmacological therapies that are targeted at prevention and treatment of the neurological and medical complications that may arise. Rebleeding, hydrocephalus, cerebral vasospasm, and seizures are the most common neurological complications while the most common medical complications include hyponatremia, pulmonary edema, cardiac arrhythmias, neurogenic stunned myocardium, fever, anemia, infection, hyperglycemia, and venous thromboembolism. Risk factors, clinical presentation, diagnosis, pathophysiology, as well as initial management, prevention, and treatment of complications will be the focus of this discussion.

Brazilein-induced contraction of rat arterial smooth muscle involves activation of Ca2+ entry and ROK, ERK pathways

Brazilein (6a,7-dihydro-3,6a,10-trihydroxy-benz[b]indeno[1,2-d]pyran-9(6H)-one) is a compound isolated from Caesalpinia sappan. The vasoactivities of brazilein were evaluated in isolated rat thoracic aorta. The results showed that brazilein can dose-dependently induce contraction of rat thoracic aorta in the resting and phenylephrine pre-evoked state. The average response to 100 microM of brazilein was 30% of the 50 mM KCl contraction, 26% of the 10 muM phenylephrine and 116% of the 20 mM caffeine contraction in comparison. The effects of vasocontraction were proved not to be endothelial dependent and could not be inhibited by alpha-adrenergic receptor blocker phentolamine, beta-adrenergic receptor blocker propranolol, M-adrenaline receptor blocker atropine, angiotensin II receptor blocker losartan or the non-selective nitric oxide synthase (NOS) inhibitor NG-Nitro-L-Arginine Methyl Ester (L-NAME). However the influx of extracellular calcium seemed to be required for this action, because depletion of extracellular calcium and the addition of L-type calcium ion channel antagonist (nimodipine and diltiazem), calcium ion channel activator (BAY-K8644) and potassium ion channel opener (pinacidil) could significantly affect the contraction induced by brazilein. We also investigated the possible signal mechanisms underlying brazilein-induced contraction using selective inhibitors. The inhibitors of myosin light chain kinase (MLCK), Rho-kinase (ROK) and extracellular signal regulated kinase (ERK) can suppress the effect of brazilein respectively, whereas inhibitors of other signaling or receptor molecules such as protein kinase C (PKC) and inositol 1,4,5-triphosphate (IP3) receptor had no effect. All these results demonstrated that brazilein can induce contraction of rat aorta, that the Ca2+ influx, ROK and ERK signal pathways and MLCK activation must be involved in the contractile processes.

Diagnosis and management of labile blood pressure during acute cerebrovascular accidents and other hypertensive crises

It is estimated that with more than 40 million adults in the United States having uncontrolled hypertension, the risk of developing ischemic or hemorrhagic stroke in this population is significant. In addition, roughly 1 of 100 patients with essential hypertension will experience a hypertensive crisis during their lifetime, and these accelerated hypertensive emergencies and urgencies complicate more than 27% of all acute medical problems in patients presenting to emergency departments (EDs) in the United States. Arterial hypertension, a prominent feature of acute stroke syndrome, usually declines spontaneously within a few days, but its presence at hospital admission or its acute development during hospitalization is often associated with worsening stroke outcome and early mortality. Control of hypertension in patients with subarachnoid and intracerebral hemorrhage, both forms of acute stroke, is directed at maintaining adequate cerebral blood flow to minimize ischemic damage and control intracerebral pressure while reducing the risk of rebleeding and developing cerebrovasospasm. Inappropriate lowering of the blood pressure in acute stroke may increase neurologic damage. However, adequate blood flow around the central area of the acute ischemic stroke or penumbra may result in ischemic cells being salvaged. Clinicians must be mindful that accelerated hypertension is associated with other types of patients seen in the ED, such as perioperative patients and patients with traumatic head injuries.

Anesthetic Considerations of Selective Intra-arterial Nicardipine Injection for Intracranial Vasospasm

Cerebral vasospasm after subarachnoid hemorrhage can decrease cerebral blood flow with the potential for stroke. Induction of Triple-H therapy (hypertension, hypervolemia, and hemodilution) is an accepted medical therapy to decrease the delayed cerebral ischemia related to vasospasm. Recently selective intra-arterial injection of nicardipine during angiography has also been proposed as a therapeutic modality for the management of distal vasospasm not amenable to balloon angioplasty. We are reporting the hemodynamic changes in 11 patients who underwent this procedure. A retrospective chart review of 15 procedures in 11 patients showed a significant change in blood pressure after the injection of nicardipine. Blood pressure changes were not different between sexes, but increase in heart rate was higher for females. A significantly higher drop in systolic blood pressure but not for diastolic blood pressure or mean arterial pressure after the injection was seen in patients who were not intubated in the intensive care unit before the procedure. Selective intra-arterial injection of nicardipine during angiography can cause significant hemodynamic instability and requires supportive management by the anesthesiologist.