Intraoperative transcranial ultrasonic monitoring for cardiac and vascular surgery

The brain is the only organ not routinely monitored by any direct method during the administration of anesthesia. Anesthesiologists rely primarily on indirect physiologic evidence provided by blood pressure, peripheral pulse oximetry, heart rate, and respiratory and anesthetic gas concentrations to determine that brain blood flow and oxygenation are adequate. The reasons for this practice are that: (1) after millions of anesthetics significant numbers of adverse neurologic outcomes have not occurred, (2) the interpretation of transcranial Doppler, electroencephalogram, and near-infrared cerebral oximetry requires experienced personnel, and (3) the evidence of cost-benefit to support monitoring is limited. Brain monitoring generally has been confined to procedures where the brain is exposed to unique insults and risks specific to the procedures and where reliance on indirect physiologic evidence of cerebral integrity has been proven to be unreliable. Transcranial Doppler monitoring is valuable in the assessment of established surgical techniques, refinement of recent surgical techniques, and development of new techniques and instrumentation. Brain monitoring with transcranial Doppler is of particular value when deviations from established surgical or anesthetic techniques may place the brain at risk for cerebral hyper- or hypoperfusion, gaseous or particulate embolization, or their combined effects. This paper discusses applications of transcranial Doppler in coronary artery bypass surgery, aortic arch procedures, pediatric cardiac surgery, carotid endarterectomy, and a few other special cases. The insight into cerebral physiology is unique to the continuous window on the brain that transcranial Doppler provides.     

Comparison of waterjet dissection and ultrasonic aspiration: an in vivo study in the rabbit brain

OBJECT: The waterjet method of dissection has been shown to enable the precise dissection of the parenchyma vessels while preserving blood in cadaveric pig brains. The waterjet device has also been applied clinically to treat various diseases and disorders without complications. Evidence still remains to be gathered as to how the instrument performs in reducing surgical trauma, intraoperative blood loss, and postsurgical brain edema. In the present study the authors investigate these parameters in a comparison between waterjet dissection and ultrasonic aspiration in the rabbit brain in vivo. METHODS: Thirty-one rabbits received identical bilateral frontal corticotomies, which were created using the waterjet device or an ultrasonic aspirator. The animals were killed 1, 3, or 7 days, or 6 weeks after surgery and their brains were processed for immunohistological analysis. Blood vessel preservation, intraoperative hemorrhage, postsurgical brain edema, and posttraumatic microglial and astoglial reactions were evaluated. Only in animals subjected to waterjet dissection were preserved vessels observed within the corticotomies. In addition, less intraoperative bleeding occurred in animals in which the waterjet was used. The microglial reaction was significantly reduced by waterjet dissection compared with ultrasonic aspiration; however, no difference in edema formation or astrocytic reactivity was observed. CONCLUSIONS: These results demonstrate that waterjet dissection appears to be less traumatic than ultrasonic aspiration with respect to intraoperative hemorrhage and postoperative microglial reactivity in the rabbit model. Nevertheless, no difference in edema formation could be demonstrated. It remains to be proven that the observed differences are of clinical relevance.     

In vivo proton magnetic resonance spectroscopy of brain tumors

The ability of magnetic resonance spectroscopy (MRS) to differentiate neoplastic brain cells and their metabolic and structural characteristics is evaluated. We examined 120 patients with brain tumors using a 1.5-tesla MRI unit and MRS. The peak areas of N-acetyl-aspartate (NAA), phosphocreatine-creatine (Pcr-Cr), choline-containing compounds (Cho), lactate, lipids, myoinositol, amino acids and the ratios of NAA/Pcr-Cr, NAA/Cho and Cho/Pcr-Cr were calculated by a standard integral algorithm. In normal brain tissue, the following metabolites were identified: NAA at 2.0 ppm, Pcr-Cr at 3.0 ppm and Cho at 3.2 ppm. The different concentrations of the metabolites examined and their role in the biochemical profile of different types of tumors are discussed. The confidence interval of the MRS versus pathology was between 0.9 and 0.954, while it was between 0.52 and 0.631 for MRI versus pathology. The Cho/Pcr-Cr ratio is a very important malignancy marker for histologic tumor grading of astrocytomas. The greater this ratio, the higher the grade of the astrocytoma. NAA/Pcr-Cr together with Cho/Pcr-Cr help specify the presence or absence of a neoplasm. Proton MRS is a useful and promising diagnostic modality not only in diagnosing but also in grading solid brain tumors.     

In vivo characterization of traumatic brain injury neuropathology with structural and functional neuroimaging

Quantitative neuroimaging is increasingly used to study the effects of traumatic brain injury (TBI) on brain structure and function. This paper reviews quantitative structural and functional neuroimaging studies of patients with TBI, with an emphasis on the effects of diffuse axonal injury (DAI), the primary neuropathology in TBI. Quantitative structural neuroimaging has evolved from simple planometric measurements through targeted region-of-interest analyses to whole-brain analysis of quantified tissue compartments. Recent studies converge to indicate widespread volume loss of both gray and white matter in patients with moderate-to-severe TBI. These changes can be documented even when patients with focal lesions are excluded. Broadly speaking, performance on standard neuropsychological tests of speeded information processing are related to these changes, but demonstration of specific brain-behavior relationships requires more refined experimental behavioral measures. The functional consequences of these structural changes can be imaged with activation functional neuroimaging. Although this line of research is at an early stage, results indicate that TBI causes a more widely dispersed activation in frontal and posterior cortices. Further progress in analysis of the consequences of TBI on neural structure and function will require control of variability in neuropathology and behavior.     

不同频率超声清洗机清洗脑科吸引器头的效果比较

目的探讨不同频率超声清洗机对脑科吸引器头的清洗效果,为消毒供应专业护士选择合适的超声清洗机提高器械清洗质量提供依据。方法将使用后且经人工染血后的脑科吸引器头300件随机分成A、B、C三组各100件。A、B、C组分10批(每批每组10件)分别放置在KUSON8895单频超声清洗机、KQ-300VDY型医用三频数控超声清洗机、GETTING2460UC单频超声清洗机中清洗。清洗时间及清洗剂浓度一致。结果三组器械清洗后,目测法合格率86.0%～95.0%,差异无统计学意义(P0.05)。三组潜血试验检测结果比较,差异有统计学意义(P0.01),其中B组的清洗效果最佳,C组次之,A组最差。结论三频数控超声清洗机能够最大化保障脑科吸引器头的清洗质量,达到预防医院感染的目的。     

Transrectal ultrasonic volumetry of the prostate: In vivo comparison of different methods

In order to assess the accuracy of various volumetric methods for screening and follow-up of prostatic disease, total prostate volume and inner zone volume were measured by transrectal ultrasonography in a screening population of 716 men. Semiplanimetric and caliper formula methods were compared with step section planimetry as the gold standard. Planimetric volumetry of the prostate is regarded as the most reproducible method for individual follow-up of total gland and inner zone volume. The prolate spheroid formula is the most reproducible of caliper formula methods for both volumes. In this study the elliptical volume was, however, more accurate than the prolate spheroid volume of the total gland, as the correlation coefficient between total elliptical volume and planimetry was higher compared to the prolate spheroid volume (0.89 vs. 0.83), and the standard deviation of the mean volumetric difference smaller. The mean total prolate spheroid volume resembled the mean total planimetric volume better than the elliptical volume did, as the mean volumetric difference was smaller. For measurement of the inner zone volume the prolate spheroid volume was more accurate than the elliptical volume. The correlation coefficient between length and planimetric volume was similar to that of width and height, which accounted for more accuracy of the elliptical volume than of the prolate spheroid volume in larger prostates. The elliptical volume might be used for incidental volumetric measurements of the total gland, and for comparison of different individuals, e.g., in preoperative evaluation or screening studies. © 1996 Wiley-Liss, Inc.     

颈前路椎间撑开的在体研究

目的:研究颈椎前路手术中撑开的扭力变化,分析撑开扭力的构成原因,为椎间撑开有关问题提供量化依据。方法:用特制的能测定撑开扭力的颈椎前路撑开器,在41例三组病人颈椎前路次全椎体切除术中测定3种状态下撑开椎体时的扭力变化,统计分析其变化趋势,并分析其临床意义。结果:撑开扭力随着撑开的高度先平稳增加,前柱完全撑开时扭力急剧增加。不同病例组撑开的扭力增幅绝对值不等,但曲线类型相似,颈椎外伤病人最大撑开扭力较颈椎退变病人明显低(P<0.01)。结论:撑开扭力增幅曲线先缓慢增加后急剧增加,术中应逐步撑开,颈椎骨折时撑开力应相应减小,撑开扭力增幅明显增加的高度为合适椎间撑开高度。     

In vivo kinematics for subjects with and without an anterior cruciate ligament

The objective of the current study was to compare kinematic patterns of anterior cruciate retaining total knee arthroplasty and posterior stabilized total knee arthroplasty. Fifteen patients received an anterior cruciate retaining total knee arthroplasty and 15 received a posterior stabilized total knee arthroplasty. All total knee arthroplasties were clinically successful (Hospital for Special Surgery score > 90). Each patient was examined during level walking using fluoroscopy. Femorotibial contact paths for the medial and lateral condyles were determined using a computer automated model-fitting technique. Ten of 15 (67%) patients receiving an anterior cruciate retaining total knee arthroplasty and 12 of 15 patients (80%) receiving a posterior stabilized total knee arthroplasty experienced anterior contact at some phase of the gait cycle. Anterior contact in anterior cruciate retaining total knee arthroplasty can be attributed to the presence of the anterior cruciate ligament, resisting the anterior tibial shear forces during gait. The reason for anterior contact observed in posterior stabilized total knee arthroplasty is unclear, possibly related to the sagittal topography (dwell-point position) of the tibial component. Increased axial rotation was seen in anterior cruciate retaining total knee arthroplasty possibly because of the preservation of the four-bar linkage within the knee. Patients receiving an anterior cruciate retaining total knee arthroplasty experienced kinematic patterns more similar to the normal knee.     

In vivo testing of an infection-resistant annuloplasty ring

BACKGROUND: An infection-resistant surface incorporated into a prosthetic cardiac valve has great potential clinical applications. STUDY DESIGN: A sewing ring construct was created using ciprofloxacin-treated polyester. Then ciprofloxacin-treated and untreated constructs were implanted subcutaneously on the dorsum of rats and inoculated with Staphylococcus aureus. At 7, 14, and 30 days animals were sacrificed and the implants were retrieved. Each implant was assessed for frank purulence and gross tissue incorporation by a blinded observer. The implants were processed for conventional histology and examined by a blinded Pathologist. Ciprofloxacin-treated rings were also implanted in the absence of a bacterial challenge. At explantation, a maximal zone of inhibition, if present, was measured. Finally, ciprofloxacin was eluted with methanol from the explanted segments and the concentration of ciprofloxacin eluted was determined. RESULTS: Ciprofloxacin-treated sewing rings had greater gross tissue incorporation than untreated rings in the presence of a bacterial challenge (P=0.005). Ciprofloxacin-treated rings also had a lower incidence of frank purulence, but this did not reach statistical significance. After 14 days of implantation, ciprofloxacin treated rings had fewer neutrophils (P=0.018) and greater histological tissue incorporation (P=0.017) than untreated rings. The explanted ciprofloxacin-treated rings maintained a zone of inhibition of 3.0+/-1.0 mm after 1 day of implantation and 1.3+/-0.6 mm after 2 days. Ciprofloxacin could be eluted in significant quantities from the explanted rings after 7 days of implantation. CONCLUSIONS: Ciprofloxacin treated polyester can be incorporated into an annuloplasty ring construct that demonstrates excellent tissue incorporation and infection resistance. This study supports the use of this construct in the mitral position in a large animal model.     

Outcome prediction in severe traumatic brain injury with transcranial Doppler ultrasonography

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