Thermal characteristics of clothing ensembles for use in heat stress analysis.

The Heat Stress Index was an early model for the assessment of heat stress. The International Organization for Standardization (ISO) standard for required sweat rate is the current generation of heat balance methods for occupational heat stress. The method assumes cotton clothing and works adequately for cotton/polyester blends. To extend the usefulness of the model, the thermal characteristics of a variety of commercially available and prototype protective clothing ensembles have been determined for application in the ISO method. The fundamental principle for assessing thermal characteristics of work clothing is establishing the critical environmental conditions in which test subjects were just able to maintain thermal equilibrium. Critical conditions were found for warm, humid conditions; hot, dry conditions; intermediate conditions of temperature and humidity; and/or moderate conditions in which metabolic rate was increased to a limiting thermal load. Typically, five subjects at each condition for each ensemble were used. Metabolic rate, average skin temperature, and the environmental conditions (air temperature and vapor pressure) were noted at the critical conditions, and the total insulation was estimated for each ensemble. From these values, the total evaporative resistance, the clothing factor for dry heat exchange (CFcl), and the clothing factor for evaporative cooling (CFpcl) were determined. When compared with reports of others on thermal characteristics the results agreed when pumping factors and clothing wetness were considered. The result was higher than expected values for CFcl and lower values for CFpcl.

Influence of family functioning and income on vaccination in inner-city health centers.

OBJECTIVES: To assess family functioning and consumer decision-making about vaccinations and to compare the results with age at vaccination. DESIGN: Self-administered survey that was mailed to parents with comparison to vaccination records from chart audits. SETTINGS: Two inner-city health centers in Pittsburgh, Pa, that receive free vaccine supplies. PARTICIPANTS: Systematic sample from the billing computer records of parents whose children were aged 2 to 4 years as of July 2, 1993. INTERVENTIONS: The survey used simplified versions of the Family Profile and the Triandis model of consumer decision-making that includes perceived consequences of vaccinations, attitude about vaccinations, social influences, and facilitating conditions (eg, ease of obtaining an appointment). MAIN OUTCOME MEASURES: Variables associated with age at vaccination for third diphtheria and tetanus toxoids and pertussis vaccine immunization and first measles-mumps-rubella immunization. RESULTS: Of 395 families, 167 responded. Higher family dysfunction scores and lower family concordance scores each were associated with receiving first measles-mumps-rubella vaccination (P < or = .02) and third diphtheria and tetanus toxoids and pertussis vaccination (P < = .02) at later ages. Many (30%-54%) of the respondents reported that they knew little about the risks and benefits of vaccination. However, knowledge about vaccines was not associated with vaccination status. Those respondents with an annual income of less than $10000 received the first measles-mumps-rubella vaccination later than those with an annual income $10000 or greater (P < .02) when the data were analyzed by age at vaccination but not when the data were analyzed as on-time vs late vaccinations. CONCLUSIONS: To increase vaccination rates in innercity clinics, strategies need to consider family dysfunction and income and not merely focus on education. The use of age at vaccination as a continuous variable offers advantages over the dichotomy of immunized vs not immunized.

Balloon test occlusion of the internal carotid artery: change in stump pressure over 15 minutes and its correlation with xenon CT cerebral blood flow.

PURPOSE: To determine whether stump pressure changes significantly over time during temporary internal carotid artery (ICA) occlusion via an endovascular balloon, and to examine correlations between stump pressure changes and cerebral blood flow (CBF) as measured by xenon CT. METHODS: Seventy candidates for ICA sacrifice were evaluated preoperatively with a test occlusion of the cervical ICA using an endovascular balloon. Measurements of ICA stump pressure above the occlusive balloon through a distal lumen in the balloon catheter were made throughout the 15-minute test. During occlusion, CBF was measured with stable xenon CT techniques. Patients were then categorized according to CBF results. RESULTS: The stump pressure changed significantly (P < .001) during the occlusive period. On average, stump pressure increased 7.7 mmHg (12%). Patients determined by xenon CT to have an asymmetric decrease in CBF with balloon occlusion did not display the upward trend in stump pressures and were significantly different (P = .013) in that respect from patients who demonstrated either no CBF change or only minimal bilaterally symmetric decreases in CBF. CONCLUSIONS: Large overlaps among the groups prohibit the use of stump pressure changes as an accurate predictor of CBF or of stroke risk in an individual patient. However, these data suggest an autoregulatory mechanism in the cerebral circulation that evolves over a period of minutes in contrast to the traditional concept of cerebral autoregulation which is thought to occur in a matter of seconds.

Imaging of the saphenous vein graft bypass of the cavernous carotid artery.

PURPOSE: To describe the radiographic appearance of the interpositional carotid saphenous vein graft and to compare the efficacy of MR angiography with conventional angiography in determining graft patency and identifying graft irregularities. METHODS: The authors examined saphenous vein graft bypasses of the cavernous carotid artery in 14 patients using CT, MR, and conventional and MR angiography. RESULTS: The course of the graft was typically more inferior, lateral, and anterior than the course of the native vessel. Mild irregularities were found in four of the grafts, but all four "filled out" in a period of months. Time-of-flight angiography was comparable to conventional angiography in four of five patients. Phase-contrast angiography was comparable to conventional angiography in nine of nine cases. CONCLUSIONS: MR angiography is a useful screening modality in the postoperative evaluation of vascular grafts.

Parent power.

The Child Development Programme is becoming increasingly known as a radically different form of health visiting and is now operating in more than ten per cent of the 200 health authorities in the United Kingdom.