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Biomedical subjects

J I Ausman

Publications and source records attributed to J I Ausman.

At least 19 recordsLinked to original sources
PubMed2000

Techniques of coiling cerebral aneurysms.

BACKGROUND: More than 200 aneurysms have been coiled at the UIC Medical Center within the last 5 years. We describe in detail the technical factors that increase the chance of complete occlusion of a cerebral aneurysm with coils. Aneurysms selected for coiling have good geometry or are in a location that is difficult to reach surgically. Patients with medical conditions that preclude surgical treatment may also undergo coiling. METHODS: Patients with aneurysms, either ruptured or unruptured, are treated under general anesthesia, fully anticoagulated and deeply paralyzed. Coiling is done under simultaneous biplane roadmapping. After the first coil has created a mesh, the aneurysm is densely packed with soft coils of decreasing diameter, until no more coils can be deployed into the aneurysm. RESULTS: The morbidity and mortality rates associated with the coiling procedure have continuously decreased over the last 5 years. The morphological outcomes have improved, due to extensive use of the remodeling technique and to advancements in materials, such as refinements in the coils themselves or the availability of over-the-wire balloon catheters in different sizes and hydrophilic wires with complex tip configurations. Twenty-one percent of the aneurysms were considered to be incompletely occluded immediately after coiling. Of this group, one-third of the aneurysms were found to be completely occluded on follow-up angiograms by 6 months; these have remained occluded. One-third were more than 95% occluded after the coiling procedure; in these patients, the dome was completely occluded, but there was a small neck remnant, which has remained stable in all patients on control angiograms obtained at 6 months and 1, 2, and 4 years; none have rebled. These patients are followed medically. The remaining one-third of the aneurysms in this subgroup were less than 95% occluded, although the dome was completely thrombosed. None of them have rebled, but the neck remnant in most has regrown over a period ranging from 6 months to 2 years. These patients have undergone a second treatment-either surgical clipping, permanent occlusion of the parent vessel, or repeat coiling using the remodeling technique. The overall rebleeding rate of incompletely occluded aneurysms is extremely low (less than 1%). CONCLUSION: The low morbidity and mortality rates and the good morphological outcome obtained in most cases make coiling a reasonable alternative to surgical clipping in properly selected cases.

Embolization, Therapeutic↗
PubMed2000

Hypoxic brain tissue following subarachnoid hemorrhage.

BACKGROUND: Subarachnoid hemorrhage can lead to cerebral ischemia and irreversible brain injury. The purpose of this study was to determine whether subarachnoid hemorrhage produces changes in brain tissue oxygen pressure, carbon dioxide pressure, or pH during surgery for cerebral aneurysm clipping. METHODS: After institutional review board approval and patient consent, 30 patients undergoing craniotomy for cerebral aneurysm clipping were studied, 15 without and 15 with subarachnoid hemorrhage. Patients with subarachnoid hemorrhage were prospectively separated into groups with modest (Fisher grade 1 or 2; n = 8) and severe bleeds (Fisher grade 3; n = 7). After a craniotomy, a probe was inserted into cortex tissue supplied by the artery associated with the aneurysm. Baseline measures were made in the presence of a 4% end-tidal desflurane level. The end-tidal desflurane level was increased to 9% before clipping of the aneurysm, and a second tissue measurement was made. RESULTS: The median time of surgery after subarachnoid hemorrhage was 2 days, ranging from 1 to 13 days. During baseline anesthesia, brain tissue oxygen pressure was 17+/-9 mm Hg (mean +/- SD) in control patients, 13+/-9 mm Hg in those with Fisher grade 1 or 2 hemorrhage, and 7+/-6 mm Hg in those with Fisher grade 3 hemorrhage (P<0.05 compared with control). Brain tissue pH was 7.10+/-0.10 in control patients, 7.14+/-0.13 in those with Fisher grade 1 or 2 hemorrhage, and 6.95+/-0.18 in those with with Fisher grade 3 hemorrhage (P<0.05). At a 9% end-tidal desflurane level, brain tissue oxygen pressure increased to 19+/-9 mm Hg and brain tissue pH increased to 7.11+/-0.11 in patients with Fisher grade 3 hemorrhage (P<0.05 for both increases). CONCLUSION: These results show that subarachnoid hemorrhage can significantly decrease brain tissue oxygen pressure and pH related to the severity of the bleed. Increasing the desflurane concentration to 9% increased brain tissue oxygen pressure in all patients and brain tissue pH in patients with subarachnoid hemorrhage with baseline acidosis.

Adult↗
PubMed2000

What percentage of surgically clipped intracranial aneurysms have residual necks?

OBJECTIVE: To determine the angiographically proven rate and persistence of occlusion of intracranial aneurysms after surgical clipping as reported in the literature. This should establish a basis for comparing surgery with new endovascular methods of treatment. METHODS: We reviewed the literature published during the period from 1979 through 1999, dividing the articles into two groups. The first group of articles reported patients undergoing surgical treatment with immediate postoperative angiography. The second group of articles documented symptomatic recurrence or regrowth of aneurysms that were surgically treated previously. The data from these articles are presented for analysis. RESULTS: During the period 1979 to 1999, six series of patients undergoing surgical treatment of aneurysms with immediate postoperative angiography were reported. These reported series comprised a total of 1,397 patients, of whom 1,370 underwent postoperative angiography demonstrating 1,569 clipped aneurysms. Residual filling was found in 82 aneurysms (5.2%) on postoperative angiography. Of the 1,370 patients, only 124 patients with 169 aneurysms were reported to have had any long-term angiographic follow-up. The second group consisted of 226 patients representing six reported groups of patients, who either presented up to 24 years after aneurysm clipping with recurrent symptoms of hemorrhage or mass effect, or had important findings on intraoperative and postoperative angiograms. CONCLUSION: The lack of information regarding both the frequency of residual filling or regrowth and long-term angiographic follow-up of patients with surgically treated aneurysms makes meaningful comparison between surgical treatments and new treatment methods for intracranial aneurysms difficult or impossible. Detailed analysis with high-quality angiography should be performed to determine the success of surgical treatment.

Cerebral Angiography↗
PubMed1999

What does measurement of brain tissue pO2, pCO2 & pH add to neuromonitoring?

In this paper the rationale behind utilizing the brain tissue measurements of oxygen, carbon dioxide, pH and temperature is evaluated in the context of ischemia. These parameters were measured using an intraparenchymal multi-parametric brain tissue monitor (Paratrend 7). The need to establish the relevance of this type of monitoring becomes acute as further experience is gained using this kind of technology. Our experience with such a device is presented and is illustrated with two clinical cases. The potential caveats and areas of possible future work are also delineated.

Acute Disease↗
PubMed1999

Measurement of ischemia by changes in tissue oxygen, carbon dioxide, and pH.

BACKGROUND: We evaluated the ability of brain tissue oxygen pressure (PO2), carbon dioxide pressure (PCO2), and pH to detect regional ischemia produced by temporary brain artery occlusion, compared with a group without artery occlusion. METHODS: Patients undergoing craniotomy for cerebrovascular surgery were recruited for this study. A 0.5-mm-diameter probe was inserted into brain tissue to measure PO2, PCO2, and pH continuously. Group 1 (n = 15) did not receive brain artery occlusion during their surgical procedure. In Group 2, brain artery occlusion was produced for aneurysm clipping (n = 10) or extracerebral to intracerebral artery bypass (n = 3). Mean arterial pressure was maintained above 90 mmHg in both groups. Measurements were made after artery occlusion or sham treatment and compared with baseline. RESULTS: Under baseline conditions, tissue PO2, PCO2, and pH were not different between the groups. In Group 2, brain artery occlusion for a median time of 7 minutes (range, 2-48 min) significantly decreased PO2 and pH and increased PCO2 compared with baseline. There were no significant changes in Group 1. During artery occlusion, PO2 decreased below 10 mmHg and/or pH decreased below 7.0 in 8 of 13 patients. CONCLUSIONS: Regional brain ischemia can be consistently detected and treated by monitoring tissue metabolism. It will be necessary in the future to identify critical levels and duration of decreases in PO2 and pH that lead to irreversible neuronal injury.

Brain↗