Effectiveness of cold water immersion for treating exertional heat stress when immediate response is not possible.

Immediate treatment with cold water immersion (CWI) is the gold standard for exertional heatstroke. In the field, however, treatment is often delayed due to delayed paramedic response and/or inaccurate diagnosis. We examined the effect of treatment (reduction of rectal temperature to 37.5 °C) delays of 5, 20, and 40 min on core cooling rates in eight exertionally heat-stressed (40.0 °C rectal temperature) individuals. We found that rectal temperature was elevated above baseline (P < 0.05) at the end of all delay periods (5 min: 40.08 ± 0.32; 20 min: 39.92 ± 0.40; 40 min: 39.57 ± 0.29 °C). Mean arterial pressure was reduced (P < 0.05) below baseline (92 ± 1.8 mm Hg) after all delay periods (5 min: 75 ± 2.6; 20 min: 74 ± 1.7; 40 min: 70 ± 2.1 mm Hg; P > 0.05). Rectal core cooling rates were similar among conditions (5 min: 0.20 ± 0.01; 20 min: 0.17 ± 0.02; 40 min: 0.17 ± 0.01 °C/min; P > 0.05). The rectal temperature afterdrop following CWI was similar across conditions (5 min: 35.95; 20 min: 35.61; 40 min: 35.87 °C; P > 0.05). We conclude that the effectiveness of 2 °C CWI as a treatment for exertional heat stress remains high even when applied with a delay of 40 min. Therefore, our results support that CWI is the most appropriate treatment for exertional heatstroke as it is capable of quickly reversing hyperthermia even when treatment is commenced with a significant delay.

A Canadian multicentre case-control study of sporadic Escherichia coli 0157:H7 infection.

OBJECTIVE: To evaluate further risk factors for Escherichia coli 0157:H7 infection including consumer preferences related to the consumption of ground beef and the role of person-to-person transmission of this infection. PATIENTS AND METHODS: A case-control study of sporadic E coli 0157:H7 infection was undertaken in five Canadian cites from June to December 1991. One hundred cases of E coli 0157:H7 infection were age- and sex-matched to 200 neighbourhood controls. Cases and controls were interviewed face-to-face to obtain information on potential risk factors for infection and health outcomes. Daycare providers of case and control children were interviewed regarding risk factors for infection at the institutional level. Contacts of cases and controls who reported diarrhea in the seven days before the case onset date were also interviewed about their symptoms and risk factors. RESULTS: All cases had diarrhea during the course of their illness and 90 (90%) reported bloody diarrhea. Four (4%) were reported to have developed hemolytic uremic syndrome; however, there were no fatalities. Sixty-one (61%) of patients were hospitalized. Two variables were associated with infection in the final conditional logistic regression model: eating pink hamburger patties (odds ratio = 12.4, P=0.0001, population attributable fraction =40.2%) and contact with a nonhousehold member suffering from diarrhea (odds ratio = 7.0, P=0.0054, population attributable fraction = 10.3%) in the seven days before illness. Forty per cent of cases and controls who indicated that they prefer well done hamburgers said they would eat a 'pink' hamburger if served to them rather than ask that the hamburger be cooked longer. CONCLUSIONS: Health care workers should remain vigilant in their efforts to educate the public as to the risks associated with the consumption of ground beef that is inadequately cooked, and the importance of personal hygiene in the prevention of enteric illness.

Small bowel tonometry is more accurate than gastric tonometry in detecting gut ischemia.

Gastric tonometer PCO2 measurement may help identify gut ischemia in critically ill patients but is frequently associated with large measurement errors. We tested the hypothesis that small bowel tonometer PCO2 measurement yields more accurate information. In 10 anesthetized, mechanically ventilated pigs subject to progressive hemorrhage, we measured gut oxygen delivery and consumption. We also measured tonometer PCO2 minus arterial PCO2 (DeltaPCO2) and calculated the corresponding intracellular pH from tonometers placed in the stomach and jejunum. We found that the correlation coefficient (r2) for biphasic gut oxygen delivery-DeltaPCO2 relationships was 0.29 +/- 0.52 for the gastric tonometer vs. 0.76 +/- 0.25 for the small bowel tonometer (P < 0.05). In addition, the critical gastric tonometer DeltaPCO2 was excessively high and variable (62.9 +/- 39.6) compared with the critical small bowel tonometer DeltaPCO2 (17.0 +/- 15.0, P < 0.01). Small bowel tonometer PCO2 was closely correlated with superior mesenteric vein PCO2 (r2 = 0.81, P < 0.001), whereas gastric tonometer PCO2 was not (r2 = -0.13, P = not significant). We conclude that measurement of gastric tonometer PCO2 yields excessively noisy and inaccurate data on the onset of gut anaerobic metabolism in hemorrhagic shock. Small bowel tonometer PCO2 is less noisy and, as a result, is superior in detecting gut hypoperfusion and the onset of anaerobic metabolism.

Heterogeneity of gut capillary transit times and impaired gut oxygen extraction in endotoxemic pigs.

We tested the hypothesis that endotoxin increases the heterogeneity of gut capillary transit times and impairs oxygen extraction. The gut critical oxygen extraction ratio was determined by measuring multiple oxygen delivery-consumption points during progressive phlebotomy in eight control and eight endotoxin-infused anesthetized pigs. In multiple 1- to 2-g samples of small bowel, we measured blood volume (radiolabeled red blood cells) and flow (radiolabeled 15-microns microspheres) before and after critical oxygen extraction. Red blood cell transit time (= volume/flow) multiplied by morphologically determined capillary/total blood volume gave capillary transit time. During hemorrhage, capillary/total blood volume did not change in the endotoxin group (0.5 +/- 4.5%) but increased in the control group (17.6 +/- 2.5%; P < 0.05) due to a decrease in total gut blood volume. Flow decreased significantly in the endotoxin group (36 +/- 10%; P < 0.05) but not in the control group (12 +/- 10%). Capillary transit-time heterogeneity increased in the endotoxin group (12.3 +/- 4.9%) compared with the control group (-5.8 +/- 7.4%; P < 0.05), predicting a critical oxygen extraction ratio 0.14 lower in the endotoxin group than in the control group (K. R. Walley. J. Appl. Physiol. 81: 885-894, 1996). This matches the measured difference (endotoxin group, 0.60 +/- 0.04; control group, 0.74 +/- 0.03; P < 0.05). Increased heterogeneity of capillary transit times may be an important cause of impaired oxygen extraction.

Adverse reactions and antibody response to four doses of acellular or whole cell pertussis vaccine combined with diphtheria and tetanus toxoids in the first 19 months of life.

To assess the safety, immunogenicity, and lot consistency of a five-component acellular pertussis vaccine combined with diphtheria and tetanus toxoid (Connaught Laboratories Limited), we randomly allocated 432 infants to receive one of three lots of an acellular pertussis vaccine or a single lot of whole cell pertussis vaccine. Infants were immunized at 2, 4 and 6 months of age and between 17 and 19 months of age. Local and systemic adverse reactions were reported significantly more frequently by recipients of the whole cell than acellular vaccine after each dose. The antibody response against pertussis toxin, filamentous hemagglutinin, and 69 kDa protein was of greater magnitude in acellular pertussis vaccine recipients than whole cell pertussis vaccine recipients. Small differences were detected amongst the vaccine lots tested. We conclude that the acellular pertussis vaccine is safe and immunogenic for the first four doses in children under 2 years of age.

Immunogenicity of a five-component acellular pertussis vaccine in infants and young children.

OBJECTIVE: To compare the reactogenicity and immunogenicity of an acellular vaccine containing pertussis toxoid, filamentous hemagglutinin, and fimbriae 2 and 3, with and without the 69-kd membrane protein, alone or combined with diphtheria and tetanus toxoids. PARTICIPANTS AND SETTING: One hundred thirty-seven 17- to 18-month-old and 22 4- to 6-year-old children who had received three or four previous doses of whole-cell vaccine, respectively, were recruited from public health immunization clinics. DESIGN AND INTERVENTIONS: Three groups of children were sequentially enrolled in the study to receive the acellular pertussis vaccine with or without a 69-kd protein (CP4 or CP5, 17- to 18-month-old children), the two vaccines combined with diphtheria and tetanus toxoids (CP4DT or CP5DT, 17- to 18-month-old children), or the CP5DT vaccine (4- to 6-year-old children). Children were assigned to the first two groups in a randomized and double-blind fashion; the last group was formed by open enrollment. Data regarding adverse reactions were recorded by the parents and collected via a structured interview administered seven times, five times during the first 72 hours. Serum samples were obtained before and 1 month after the immunization, and antibodies against each constituent of the vaccine were measured. RESULTS: A systemic adverse reaction was reported in 40% to 65.7% of 17- to 18-month-old and 38.1% of 4- to 6-year-old children; no severe reactions occurred. A local reaction was reported in 8.6% to 29.4% and 71.4% of children, respectively. No differences were detected between respectively. No differences were detected between vaccines; inclusion of the 69-kd membrane protein did not increase reactogenicity. All vaccines elicited an antibody response to all antigens contained in the formulation. CONCLUSIONS: The five-component acellular pertussis vaccine (Connaught Laboratories Ltd, Willowdale, Ontario) is safe and immunogenic in 17- to 18-month-old and 4- to 6-year-old children. The 69-kd protein was immunogenic, and its inclusion neither increased side effects associated with the vaccine nor adversely affected the antibody response to the other components.

Can Haemophilus influenzae type b-tetanus toxoid conjugate vaccine be combined with diphtheria toxoid-pertussis vaccine-tetanus toxoid?

OBJECTIVE: To assess the side effects and immune responses after three serial doses of PRP-T vaccine (a Haemophilus influenzae type b [Hib]-tetanus toxoid conjugate vaccine) given concurrently or mixed with adsorbed DPT vaccine (diphtheria toxoid-pertussis vaccine-tetanus toxoid). DESIGN: Multicentre randomized controlled trial. SETTING: Four public health units in western Canada. PARTICIPANTS: Healthy infants 8 to 15 weeks old at entry who were able to receive routine primary vaccinations. Of 444 infants enrolled, 433 (98%) completed the study. INTERVENTIONS: All infants received PRP-T and DPT vaccines at 2, 4 and 6 months of age: half received them mixed in one injection and the others as separate, bilateral injections. MAIN OUTCOME MEASURES: Side-effects 24 and 48 hours after each dose and serologic responses to each vaccine component. RESULTS: Follow-up was obtained after all 1312 vaccinations. Fever was infrequent in the two treatment groups. Local adverse effects of the PRP-T vaccine were infrequent and mild (e.g., redness was noted in 5.9% of cases and the area of redness was more than 2.5 cm in diameter in 0.8%). The incidence rate of local effects of the DPT-containing vaccines was the same in the two groups except for tenderness, which was more frequent in the group given the mixed vaccine (26.6% v. 17.9%, p < 0.001). Serologic data were available for 97% of the subjects. After the three doses 98.1% of the subjects had a PRP antibody level of 0.15 micrograms/mL or more, and 87.9% had a level of 1.0 micrograms/mL or more, both levels compatible with protection against Hib. Responses to PRP-T were comparable between the treatment groups as were responses to the diphtheria and tetanus toxoids. Pertussis agglutinin titres were reduced after administration of one of two PRP-T lots mixed with DPT vaccine, but responses to four other pertussis antigens were not impaired. CONCLUSION: PRP-T vaccine is well tolerated and immunogenic. Combined PRP-T and DPT vaccines performed satisfactorily and may be the preferred method of administration.

Support groups for parents of children with emotional disorders: a comparison of members and non-members.

This study involving more than 800 parents whose children have emotional disorders focuses on comparisons between parents who are members of support groups and those who are not. While no difference was found between members and non-members on most demographic variables, members reported needing and using more information and services and found each more difficult to locate than non-members. Thirty-one percent of all respondents identified involvement with other parents as the most helpful activity in coping with their child's problems.

Family-centered services: implications for mental health administration and research.

Efforts to move the system of care for children with serious emotional disorders toward community-based alternatives has prompted a growing recognition of the need for supportive services for families. This article examines the shifts in policy and administrative practice that are needed in order to move toward a family-centered system of care. Proactive administrative support is particularly important in this system shift. Four important barriers to a family-centered system of care are examined: (1) efforts have tended to focus on the child as the unit of services, rather than on the family; (2) efforts have tended to focus primarily on mental health services, rather than considering the full range of services needed by the child and family; (3) efforts have tended to emphasize formal services, often ignoring the support provided by informal networks; and (4) the resources and expertise of parents and other family members have not been used. New roles for parents--which involve working with administrators and researchers are discussed.

Blending administrative and community organization practice: the case of community residential facilities.

The authors discuss the management of community programs serving deinstitutionalized populations. They make a case for the concept of "community integration" (re-entry into society), arguing that translating the concept into meaningful practice requires clearer specification of the relevant client communities and calls for a blending of traditional administrative and community organizations skills, with resultant implications for social work education. Illustrations are drawn from the field of mental health and the needs of the chronically mentally ill.

Distribution of internal carotid artery blood flow in the pony.

This study determined whether blood flow through the internal carotid artery (ICA) could be used to sample total cerebral blood flow in the pony. To answer this question we considered both the anatomic arrangement of the ICA in cadavers and the relative distribution of ICA blood flow to cerebral and extracerebral tissue using radioactive microspheres. Acrylic corrosion casts of the ICA indicated that this vessel traveled directly to the base of the brain, contributing to the formation of the circle of Willis, and did not send any significant branches to other tissues. Two vessels (internal ethmoidal artery and internal ophthalamic artery) did arise anteriorly from the circle of Willis and were, therefore, indirectly supplied by the ICA. Injection of radioactive microspheres of 15 microns diameter indicated that blood flow to extracerebral structures supplied by the internal ethmoidal and internal ophthalamic arteries was less than 5% of total ICA blood flow. Increases in ICA blood flow as measured with an electromagnetic flowmeter during isocapnic hypoxia (arterial PO2 near 40 Torr) in the awake pony (n = 6) were compared with increases in total brain flow as measured with radioactive microspheres (n = 6). ICA blood flow increased 40% compared with a 38% increase in total brain blood flow as measured with microspheres. We conclude that the ICA supplies predominantly brain tissue (approximately 95%) and that changes in ICA blood flow are representative of changes in total brain blood flow in the awake pony.

Physiological modifications in the production and repair of methyl methane sulfonate-induced breaks in the deoxyribonucleic acid of Escherichia coli K-12.

The medium in which Rec(+) strains of Escherichia coli K-12 are grown affected their sensitivity to treatment with methyl methane sulfonate (MMS). Rec(+) cells grown to the stationary phase in glucose-enriched nutrient broth (GNB) were more resistant to MMS than cells grown in nutrient broth (NB). The repair of MMS-induced breaks (or alkali-labile bonds) in the deoxyribonucleic acid (DNA) from E. coli K-12 strains AB1157, AB1886 uvrA6, and SR111 recA13 recB21 grown in GNB and NB media was examined by means of alkaline sucrose gradient centrifugation. It appeared that essentially all of the repair of breaks that occurred, as evidenced by an increase in "molecular weight," took place within 10 min after treatment with MMS under our conditions. Cell survival was highest in cells for which the size of the DNA after the post-treatment incubation was the largest. The largest DNA after post-treatment incubation was found in Rec(+) cells grown in GNB medium. The results suggest that these cells may have an enhanced capacity for repairing breaks in DNA.