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Biomedical subjects

F S Brauer

Publications and source records attributed to F S Brauer.

8 recordsLinked to original sources
PubMed1993

Total blood flow to arteriovenous malformations.

Normal perfusion pressure breakthrough is considered to be a great hazard during or after resection of large arteriovenous malformations (AVMs). This article presents the total blood flow to the AVMs, particularly those of greater than 3 cm in diameter (greater than 14.1 cm3 in volume), which have multiple compartments. The total blood flow into the AVMs in the sensory-motor area in 6 patients averaged 830 +/- 285 cc/min and those in the visual area in 4 patients averaged 358 +/- 33 cc/min. These flow values were compared to total flow through the intracranial arteries (756 cc/min). Large volume of blood flow into the AVMs carries a significant post-operative risk of normal profusion pressure breakthrough. Redistribution of blood flow from large AVMs into the cerebrovascular bed is an important factor for circulatory regulation to occur after their resection. The risk of normal profusion pressure breakthrough must be minimized by surgical technique discussed in the text.

Adolescent↗
PubMed1991

Persistent sacral nerve root deficits after continuous spinal anaesthesia.

Neurological deficits following spinal anaesthesia are rare. We report two cases of persistent sacral nerve root deficits after continuous spinal anaesthesia (CSA) performed with hyperbaric lidocaine through a lumbar microcatheter. In both cases the dose of 5% lidocaine (5.7 and 4.3 ml) was greater than usual. In the immediate postoperative period the constellation of neurological deficits included perianal hypaesthesia, lower extremity paresis, urinary retention, and difficult defaecation. Both patients have residual perianal hypaesthesia and difficult defaecation. In these cases, the high-dose requirements of local anaesthetic via microcatheter CSA with focal sensory block suggests nonuniform distribution of the hyperbaric lidocaine. Microcatheter CSA may convey a unique risk of maldistribution of the local anaesthetic solution and local neurotoxicity.

Aged↗
PubMed1990

Direct approach to arteriovenous malformations in functional areas of the cerebral hemisphere.

The natural history of patients with arteriovenous malformations (AVM's) suggests that serious morbidity associated with AVM's in functional areas is likely to be much greater than in silent areas. Various modes of treatment of AVM's in functional areas, including direct surgical intervention, embolization, and irradiation, have been considered to carry high risks. The authors advocate direct surgical intervention to these AVM's via a microsurgical technique based on knowledge of the hemodynamic anatomy of AVM's. The technique is designed to circumscribe the AVM without removing any surrounding cortical tissue or white matter and to preserve microcirculation in the functional area. Controlled hypotension (mean arterial blood pressure 40 to 60 mm Hg) is appropriate to enhance the safety of surgical procedures without causing metabolic and electrophysiological dysfunction. Another means to prevent neurological complications is multi-staged resection of larger AVM's, which permits obliteration compartment by compartment. This technique has the advantage of maintaining circulatory sufficiency in the functional area. There was no mortality among 56 patients who underwent the surgical procedure described. Of those, 55 patients resumed their preoperative occupation and one patient became self-sufficient.

Adolescent↗
PubMed1989

The effect of fentanyl anesthesia and intrathecal naloxone on neurologic outcome following spinal cord injury in the rat.

Whereas opiate receptor agonists have resulted in spinal cord damage; opiate receptor antagonists have demonstrated protection against spinal cord injury. Because opioids are used in clinical anesthesia, the effect of an opiate antagonist was evaluated on neurologic outcome in a rat model of spinal cord injury occurring during opioid anesthesia. One day prior to spinal cord injury, a catheter was inserted into the spinal subarachnoid space with the tip at T8. On the day of spinal cord injury a balloon tipped catheter was inserted in the epidural space with the tip at the thoracolumbar junction. Spinal cord injury was produced by balloon inflation during one of the following states: 1) group 1 (A/S), injury was produced in awake rats and saline was administered in the subarachnoid space immediately following injury; 2) group 2 (F/S), injury was produced during a fentanyl/nitrous oxide (N2O) anesthetic, and subarachnoid saline administered; and 3) group 3 (F/Nx), injury was produced during a fentanyl/N2O anesthetic, and subarachnoid naloxone (1 mg/kg) was administered immediately following injury. Dose-response curves describing the relationship between the duration of balloon inflation and the percentage of animals with a persistent neurologic deficit were constructed and compared for differences by use of a group t test. The duration of balloon inflation required to produce a neurologic deficit was greater in both the F/S and F/Nx groups than in the A/S group (P less than 0.05). There was no difference between the F/S and F/Nx groups. In summary, in rats receiving a fentanyl/N2O anesthetic, neurologic outcome was improved compared with the awake state.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia Recovery Period↗
PubMed1989

The effect of hypervolemic hemodilution with and without hypertension on cerebral blood flow following middle cerebral artery occlusion in rats anesthetized with isoflurane.

The effect of hypervolemic hemodilution or hypervolemic hemodilution with dopamine-induced hypertension on cerebral blood flow (CBF) was investigated during 1.2 MAC isoflurane anesthesia in rats (n = 24) subjected to middle cerebral artery occlusion (MCAO). Prior to MCAO each animal was randomized to one of the following groups: 1) control, mean arterial pressure (89 +/- 10 mmHg [mean +/- SD]), blood volume, and hematocrit (46 +/- 1) were not manipulated; 2) hypervolemic hemodilution (HH), 30 min before MCAO, 5% albumin was administered to reduce the hematocrit to 29-32%; or 3) hypervolemic hemodilution/dopamine hypertension (HH/Dop), hemodilution was accomplished and dopamine (10 micrograms.kg-1.min-1) was infused during the ischemic period to achieve a mean arterial pressure of 111 +/- 10 mmHg (mean +/- SD). Ten minutes after occlusion of the left middle cerebral artery, CBF was determined using 14C-iodoantipyrine. Five coronal brain sections were analyzed to determine the area within each brain section with CBF ranges of 0-15 ml.100 g-1.min-1 and 15-23 ml.100 g-1.min-1. The area of 0-15 ml.100 g-1.min-1 CBF was less in both the HH and HH/Dop groups compared with control (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1985

Effect of chronic alcohol consumption on rat brain microsome lipid composition, membrane fluidity and Na+-K+-ATPase activity.

The present study reports differences in phospholipid classes, fatty acids of individual phospholipids, and changes in membrane fluidity and Na+-K+-ATPase activity in brain microsomes of rats maintained on an alcohol diet for 35 days compared to sex, age and weight-matched control rats maintained on a calorically-equivalent, non-alcohol diet. Although no difference in Na+-K+-ATPase activity was found in microsomes from alcohol vs control rats when measured in the absence of added alcohol, the presence of low concentrations of ethanol (less than 100 mM) stimulated, while high concentrations (greater than 100 mM) inhibited enzyme activity. The stimulation was differentially expressed in that the microsomal enzyme from alcohol rats was stimulated to a lesser extent than the enzyme from control rats. However, the inhibiting effect of high concentrations of alcohol was similar in microsomes from both alcohol and control rats. Also in membranes from alcohol rats, there was a lower quantity of phosphatidylethanolamine (PE) and higher quantities of phosphatidylserine (PS) and phosphatidylinositol (PI) compared to membranes from control rats. The major change in fatty acid composition was a reduction in the level of polyunsaturated fatty acids, which was particularly evident in PI and PS. The linoleic acid: arachidonic acid ratio (18:2/20:4) and the saturation:unsaturation ratio were also increased in PI and PS in membranes from alcohol animals. However, the ratio of n-6/n-3 fatty acids remained the same or was reduced in membranes from alcoholic animals. Although no difference in the inherent "fluidity" of membranes from alcohol vs control rats could be demonstrated by electron paramagnetic resonance, molecular tolerance to ethanol was demonstrated in the membranes from alcohol rats by the resistance to the disordering effects of added ethanol.

Alcoholism↗
PubMed1975

Heparin therapy during extracorporeal circulation. II. The use of a dose-response curve to individualize heparin and protamine dosage.

Because the administration of heparin and protamine according to a set protocol will fail to anticoagulate safely or neutralize appropriately a significant number of patients, a method of monitoring heparin therapy during cardiopulmonary bypass is presented. A dose response curve relating heparin dosage to its effect on the activated coagulation time (ACT) can be determined with sufficient accuracy for clinical purposes from three ACT's. Preparation of such a curve makes it possible to maintain anticoagulation in a safe range during bypass and minimizes the number of monitoring tests of coagulation required. At the conclusion of bypass, this curve can be used to predict the precise amount of protamine needed for neutralization. Freed from the confusing effects of hyperheparinemia or protamine excess, the physician can diagnose and treat postoperative bleeding problems much more readily.

Blood Coagulation Tests↗