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Biomedical subjects

William Long

Publications and source records attributed to William Long.

8 recordsLinked to original sources
PubMed2006

Discordance between lactate and base deficit in the surgical intensive care unit: which one do you trust?

PURPOSE: Both lactate and base deficit (BD) are used as predictors of injury severity and mortality. We examined the significance of these measures when used in combination, and particularly when they provide conflicting data. METHODS: We reviewed all intensive care unit patients with simultaneously obtained lactate and BD measurements. The ability to predict mortality and hospital stay was compared alone, in combination, and when there was disagreement between the measures. Receiver operating characteristic curves were generated to compare predictive abilities. RESULTS: There were 1,298 patients with 12,197 sets of paired laboratory data; 1,026 trauma patients and 272 surgical patients. Lactic acidosis was present in 41% and a significant BD level (> 2) was found in 52%. Nonsurvivors had higher admission lactate (6.2 vs. 3.3) and base deficit (6.1 vs. 3.2) levels than survivors (both P < .01), with a modest correlation (r = .52) between the measures. The admission lactate and BD levels had similar predictive ability for mortality, with areas under the receiver operating characteristic curve of .7 and .66, respectively (both P < .01). However, the predictive ability of the BD level decreased significantly during the intensive care unit stay (area, .5) compared with lactate level (area, .68). Lactate and BD levels disagreed in 44% of all laboratory sets. In patients with a normal lactate level (< 2.2), the BD level had no predictive ability for mortality (area, .48; P = .26). However, in patients with a normal BD level (< 2.0), the lactate level retained its predictive ability for mortality (area, .67; P < .01). Lengths of stay were longer among patients with an increased lactate level, even when the BD level was normal. There was no improvement in predictive ability using a combination of the 2 measures. CONCLUSIONS: Both lactate and BD levels may be used to identify lactic acidosis and predict mortality at admission. Increased lactate levels predict mortality and a prolonged course regardless of the associated BD level, whereas an increased BD level has no predictive value if the lactate level is normal.

Acid-Base Imbalance↗
PubMed2006

Three-dimensional analysis of alignment error in using femoral intramedullary guides in unicompartmental knee arthroplasty.

We used computerized simulations with 3-dimensional models of 20 cadaver femora, calculated from computed tomographic scans, and a model of a rod measuring 200 x 5 mm to study femoral alignment accuracy for unicompartmental knee arthroplasty via minimally invasive reconstruction. The anatomical axis and insertion site were identified on each femur. A simulation of all feasible flexion-extension and varus-valgus orientations was performed. The average rod orientation was 3.2 degrees flexion and 2.5 degrees valgus. The range of orientation was 3.2 degrees extension to 9.7 degrees flexion and 4.5 degrees varus to 8.9 degrees valgus. The study suggests that a short narrow intramedullary rod inserted according to the manufacturer's specifications does not accurately find the anatomical axis and may lead to poor alignment of the femoral prosthesis. Given our finding of consistent bias toward excessive flexion and valgus alignment, we recommend that the operating surgeon carefully plan the insertion point of the intramedullary rod during surgery to compensate for this bias.

Arthroplasty, Replacement, Knee↗
PubMed2005

Extracting diagnoses from discharge summaries.

We have developed a program for extracting the diagnoses and procedures from the past medical history and discharge diagnoses in the discharge summary of a case and coding these using SNOMED-CT in the UMLS. The program uses a limited amount of natural language processing. Rather, it makes use of the relatively standard structure of the discharge summary, a small dictionary to divide the text into phrases, and the extensive collection of phrases for concepts in the UMLS to do the coding. With this approach the program finds 240 of 250 desired concepts with 19 false positives in 23 discharge summaries.

Diagnosis↗
PubMed2004

Urgent and emergent thoracotomy for penetrating chest trauma.

BACKGROUND: Resuscitative thoracotomy (TCY) after trauma has an overall dismal survival rate, yet patients with isolated penetrating chest wounds have the best chance of meaningful recovery. Although the major factor in outcome is presenting physiology, the site of the TCY may influence survival, with the operating room offering a superior environment to the emergency room. PURPOSE: The purpose of this study was to evaluate the impact of location of TCY on outcome after penetrating chest injury. METHODS: This was a multicenter study of patients admitted with either stab (SW) or gunshot wound (GSW) to the chest, with systolic blood pressure < or = 90 mm Hg, and who underwent TCY within 60 minutes of arrival. Time to TCY, Injury Severity Score, location of TCY (emergency room, operating room, or resuscitation room), and detectable systolic pressure at admission were among the factors studied. RESULTS: Over a 4-year period, 78 SW and 140 GSW victims underwent TCY. GSW victims had greater Injury Severity Scores (39.4 +/- 23.1 for GSW vs. 27.2 +/- 15.7 for SW, p < 0.001) and mortality (69% for GSW vs. 37% for SW, p < 0.001). No parameter studied was found to be significantly associated with survival after SW. After GSW, survival was 13.5 times more likely if TCY was performed in the resuscitation room (confidence interval, 3.3-54.6) and 22 times more likely if it was performed in the operating room (confidence interval, 6.7-73.7). CONCLUSION: Although patient selection is the primary factor determining outcome, there may be an independent benefit for performing TCY after GSW in a specialized resuscitation room or the operating room.

Abbreviated Injury Scale↗
PubMed2004

Simple fiber-optic-based sensors for process monitoring: an application in wine quality control monitoring.

The goal of this research was to develop a simple and economical fiber-optic sensor technology for agrifood process monitoring. Toward this end, two fiber-optic sensors were developed to be used in combination: a single reflection V-bend sensor and a single fiber air-gap probe. The former is designed to be sensitive toward refractive index and the latter towards absorption. Experiments indicate that the micromachined V-bend fiber refractometer is most sensitive when the bend angle is centered around 140 degrees, at which angle the sensor may resolve changes in refractive index as small as 0.00015. Additionally, the V-bend sensor was found to be non-responsive toward sample absorption even in extremely absorbing solutions. The air-gap design absorption sensor, most commonly used for measurements in highly colored media, was found to be slightly sensitive towards refractive index. When the two sensors are used together, the response of the absorption sensor may be corrected for. This sensor combination is able to provide accurate measurements in situations where Beer's law is not obeyed. Results are presented that show that the sensor pair was successfully used to monitor wine sugar content (Brix), and color density and hue, parameters related to the age of the wine.

Absorption↗
PubMed2002

Polyethylene liner cementation into fixed acetabular shells.

A patient presenting with a secure cementless acetabular component and with femoral head penetration through the polyethylene liner is a common clinical problem. Cementing a new liner into the fixed shell is one option. We evaluated this option in a clinical series of 17 cases and with a preliminary mechanical study. In the 1 clinical failure (5.9%), the failure occurred at the cement-liner interface. The most important variable in optimizing the mechanical strength of the cemented liner construct was adequate preparation of the cement-liner interface. This approach to treating the patient with a fixed cementless shell and a worn polyethylene liner can provide a durable construct with minimal morbidity.

Aged↗