Biomedical subjects

Stephen Liu

Publications and source records attributed to Stephen Liu.

4 recordsLinked to original sources

PubMed2005

Detection of small vessels with electron beam computed tomographic angiography using 1.5 and 3 mm collimator protocols.

OBJECTIVES: To evaluate the effect of scanner collimation on the ability to detect small cardiac vessels using electron beam CT coronary angiography (EBA). MATERIALS AND METHODS: EBA scans from 40 patients who underwent study on two separate occasions with 3 mm (initial scan) and 1.5 mm (follow-up scan) collimation protocols were analyzed. Vessels of <2 mm in diameter were identified. RESULTS: The 1.5 mm collimation allowed 3-D visualization of 129 vessels<2 mm in diameter, while 3 mm collimation only allowed visualization of 89 vessels (p<0.001). The right coronary artery branches and distal LAD segments though were not displayed satisfactorily in almost half of the 3-D studies with either protocol. CONCLUSIONS: There was significant improvement in detection of small cardiac vessels with a 1.5 mm collimation EBA protocol compared to a 3 mm protocol. Both protocols though were insufficient for reliable visualization of the right coronary artery branches and distal LAD segments.

Coronary Angiography↗

PubMed2004

Custom-fit versus premanufactured braces.

Custom-made and off-the-shelf functional knee orthoses from four manufacturers were evaluated. Anterior tibial translation testing was performed using a pneumatic mechanical surrogated knee. The mechanical surrogate was interfaced with a servohydraulic materials testing system, which applied all anterior/posterior displacements to an ultimate anterior load of 400 N. Comparison of the individual custom versus premanufactured braces showed that the custom braces demonstrated a statistically significant difference for restraining anterior displacement (P=.0001 to P=.0005). Pooled data from all tests showed that the custom brace measurements as a group restrained anterior displacement better than the premanufactured brace group by a mean difference of 0.84 mm (P=.0001). The authors question whether such small, sub-millimeter findings between custom and off-the-shelf functional derotation braces represent any clinically significant differences.

Braces↗

PubMed2003

Cardiovascular abnormalities in sleep-disordered breathing.

The role of sleep-disordered breathing (SDB) in the development of persistent daytime pulmonary hypertension (PH) and cor pulmonale is controversial and has not been extensively studied. In this review we discuss the physiological changes that occur during SDB in the cardiovascular system, as well as review the most recent literature examining the relationship between SDB and PH/cor pulmonale. The literature suggests that much of the PH and right heart dysfunction seen in SDB is related to concurrent obesity and underlying lung disease, although it does appear that isolated SDB (in the form of obstructive sleep apnea) may be responsible for a small but significant degree of PH. The clinical consequences of this, however, remain unclear.

Journal Article↗

PubMed2003

Impact of critical bed status on emergency department patient flow and overcrowding.

OBJECTIVE: To compare measurements of emergency department (ED) patient flow during periods of acute ED overcrowding and times of normal patient volume (NPV). METHODS: Retrospective ED chart review comparing ED flow for patients treated in a tertiary care teaching hospital during periods of ED overcrowding, defined as critical bed status (CBS), and NPV. All periods of CBS during July 2001 were identified. CBS time intervals were matched with NPV times by month, day of the week, time of day, and number of care providers. All patients registered during these matched time intervals were reviewed. Times were collected for each of the following activities: check-in, bed placement, physician assessment, first intervention, and disposition. Corresponding intervals were calculated in minutes. Triage category was used as a marker of illness severity (1 = most severe, 5 = least severe). Descriptive statistics were performed. RESULTS: One hundred eighteen patient charts were reviewed: 61 CBS and 57 NPV. There was no statistical difference in illness severity between the two groups. In the cumulative analysis, patients waited significantly longer for an ED bed (30.4 min, p = 0.01) but did not experience significant delays in other intervals. Triage category analysis revealed no significant difference in triage 2 patients. Intermediate-severity patients (triage 3) waited longer in every interval and significantly longer for physician assessment (30.8 min longer, p < 0.05). Low-severity patients (triage 4) waited longer for an ED bed (40 min, p = 0.02) but did not experience other significant delays. CONCLUSIONS: During times of acute overcrowding, the most significant delay occurs awaiting placement in the ED bed.

Bed Occupancy↗