In the statistical interpretation of forensic glass evidence it is standard practice to make the assumption of homogeneity of the refractive index (RI) of the source glass, or of localized homogeneity. However, the work of Locke and Hayes showed that, for toughened windscreen glass, this assumption might not be true. This work is well cited, but there appears to have been little follow-on published research. Furthermore, the toughening process is something known to affect the refractive index, and is a process that float glass does not undergo. Float glass is a major component of casework in New Zealand and for that reason it would be interesting to know whether the findings of Locke and Hayes apply when dealing with float glass. In this paper we describe an experiment similar to that of Locke and Hayes, systematically examining the variation of RI in a pane of float window glass. It was found that, although there were no systematic differences in refractive index, there were observable differences across the pane.

Journal Article↗

PubMedDate not supplied

Inconsistencies in genetic counseling and screening for consanguineous couples and their offspring: the need for practice guidelines.

PURPOSE: To determine current practices of genetic counseling and screening for consanguineous couples, their pregnancies and children, and to compare these practices to recommendations in the literature. METHODS: A questionnaire was mailed to 1,582 board certified genetic counselors and medical geneticists in the United States. RESULTS: The return rate was 20% (n = 309). There was wide variation in the risk figures quoted to consanguineous couples to have offspring with birth defects and mental retardation (1% to 75% for incest between first-degree relatives, and 0.25% to 20% for first cousin unions). Suggested screening practices differed for consanguineous unions before conception, during pregnancy, following birth, and for children placed for adoption. Most respondents recommended screening based on ethnicity, yet disagreed as to which genetic disorders to include. CONCLUSIONS: To standardize genetic services, guidelines for screening the offspring of consanguineous unions are needed. A consensus should be reached as to the empirical risks for genetic disorders, birth defects, and mental retardation that may impair the offspring of consanguineous unions, with definition as to what these disorders are, and if the data applies to global populations. Guidelines should consider costs, the sensitivity and specificity of DNA and biochemical testing, and current practices of prenatal and newborn screening. Consideration should be given to screening based on ethnicity, particularly in populations where consanguineous unions are common, while remaining sensitive to cultural belief systems. Recommendations for screening healthy children from consanguineous unions to be placed for adoption pose ethical challenges.

Child↗

PubMedDate not supplied

Extraordinary analgesic requirement in a patient previously unexposed to narcotics.

Patient-controlled analgesia (PCA) is a relatively new therapeutic modality that allows patients to administer doses of intravenous narcotics, using a syringe pump and sequencing device. We used PCA to deliver analgesic therapy to a 35-year-old man seriously injured in an aviation accident. Although the patient gave no previous history of narcotic use or abuse, he required morphine dosing rates as high as 56 mg/h to maintain adequate analgesia. The delivery of relatively high doses of narcotic was not accompanied by significant sedation, as might be expected. The patient underwent two surgical procedures while on PCA therapy. Following each procedure, dosing requirements increased, but within three days after each operation, dosing tapered. The patient was converted to oral hydromorphone therapy, which gradually was tapered and then discontinued. PCA should be considered a useful therapeutic adjunct in the management of patients refractive to empirical narcotic analgesic regimens.

Adult↗

PubMedDate not supplied

Diffusion of laparoscopic cholecystectomy in the Veterans Affairs health care system, 1991-1995.

CONTEXT: Laparoscopic cholecystectomy has become the most widely used treatment for gallbladder disease. In HMO, Medicare, and fee-for-service settings, cholecystectomy rates increased 28% to 59% after introduction of laparoscopic cholecystectomy. OBJECTIVE: To investigate the impact of the introduction of laparoscopic cholecystectomy on cholecystectomy rates and the operative mortality rate in Veterans Affairs (VA) hospitals. DESIGN: Sequential cross-sectional study. PATIENTS: All patients who underwent cholecystectomy from 1991 (before introduction of laparoscopic cholecystectomy) to 1995. SETTING: 133 VA hospitals. OUTCOME MEASURES: Cholecystectomy rates, use of laparoscopic or open cholecystectomy, and operative mortality rate. RESULTS: The annual number of cholecystectomies in the VA system increased by 10% from 1991 to 1995; the laparoscopic procedure accounted for 25% of the caseload in 1992 and 52% in 1995. Compared with patients having laparoscopic cholecystectomy, those having open cholecystectomy were more likely to be older, be male, and have acute cholecystitis or comorbid illnesses (P < 0.001). The operative mortality rate of open cholecystectomy increased by 46% during this 4-year period (from 2.4% to 3.4%) and was constant for laparoscopic cholecystectomy (about 0.5%). Given the increasing use of the laparoscopic procedure, however, the overall mortality rate of cholecystectomy during surgery decreased by 22% (from 2.4% to 1.8%). Despite increased use of the surgery, the absolute number of deaths decreased by 9%. CONCLUSIONS: The introduction of laparoscopic cholecystectomy in the VA system was not accompanied by a large increase in cholecystectomy rates, as it was in fee-for-service, Medicare, and HMO systems. Because the rate of operations has changed only slightly, the total number of cholecystectomy-related deaths has decreased.

Cholecystectomy, Laparoscopic↗

PubMedDate not supplied

Morphine requirements using patient-controlled analgesia: influence of diurnal variation and morbid obesity.

The influence of diurnal variation and morbid obesity on the morphine requirements of patients using patient-controlled analgesia (PCA) was studied. Forty-six patients undergoing either elective (Group I) or gastric bypass (Group II) surgery composed the study group. Patients were allowed to use the PCA machine for 36 to 72 hours postoperatively to deliver 0.6 mg/sq m doses of morphine sulfate intravenously. Counters on the device indicating the number of doses received were monitored every two hours along with vital signs and a pain and sedation rating. Dosing rates were studied with regard to the time of day. Morbid obesity had no significant effect on dosing rate requirements. Analyses revealed a significant diurnal rhythm in morphine dosing rate requirements despite a 27-fold interpatient variability. Peak analgesic use was at 0900, and the nadir was at 0300. Patient pain rankings did not indicate any changes in pain status, demonstrating PCA's use of analgesia as an endpoint for dosing. Sedation status showed a higher degree of sedation at night when compared with the daytime values, documenting that sedation was not drug-induced. There is a circadian variation in narcotic analgesic need in the postoperative patient that is met appropriately by PCA.

Adult↗