Biomedical subjects

T To

Publications and source records attributed to T To.

At least 55 records · Page 3Linked to original sources

PubMed1996

A cohort study on childhood asthma admissions and readmissions.

BACKGROUND: Admissions to hospitals for childhood asthma seem to be increasing, even though admissions for other childhood conditions are decreasing. We studied admissions and readmissions for childhood asthma in Ontario in an attempt to uncover factors relating to the admission patterns. METHODS: Using the hospital discharge data from the Canadian Institute for Health Information, 28,646 children with diagnoses of asthma were identified from April 1, 1989, to March 31, 1992. RESULTS: The admission rates for asthma among children in Ontario showed a 14.8% decrease from 1987 to 1992. This decline was observed primarily in 5- to 17-year-olds. Younger children had a fourfold risk of hospital admission for asthma. In the 4 years studied, 10,427 children (36.4%) were readmitted at least once, representing 22,114 readmissions, 16,196 (73.2%) of which were for asthma. The 6-month probabilities of readmission for asthma were 20.0% (0- to 4-year-olds) and 11.7% (5- to 17-year-olds). The estimated relative risks (RRs) indicated that younger children had a significantly higher risk of readmission for asthma (RR, 1.38; 95% confidence interval, 1.30 to 1.46) or asthma-related causes (RR, 5.02; 95% confidence interval, 4.16 to 6.05). CONCLUSIONS: The observed increasing trend in admissions for asthma among children in the 1970s and 1980s leveled off in the early 1990s. The declining admission rates were largely caused by the lower admission rates among school-aged children from 5 to 17 years. The relatively high admission and readmission rates of preschool children are still a concern. Further research is necessary to examine factors that influence admissions for asthma among young children.

Adolescent↗

PubMed1996

Risk factors for breast cancer mortality among the National Breast Screening Study of Canada participants.

We studied the relationship between risk factor information and breast cancer mortality by means of a case control study, nested within the population of the National Breast Screening Study of Canada (NBSS). The characteristics of women aged 40-59 years, identified at the initial screen, who subsequently died of breast cancer up to 7 years from the initial screen, were compared with those of controls drawn from the same population. Among the factors evaluated in this study, number of live births and presence of symptoms in the breast revealed on direct questioning were found to be significantly related to breast cancer mortality. The results suggest a decrease in risk of dying of breast cancer associated with one or more live births (OR: 0.79, 95% CI: 0.68, 0.93), and an increase in risk of dying of breast cancer associated with symptoms in the breast revealed on direct questioning at the initial screen (OR: 2.01, 95% CI: 1.20, 3.37).

Adult↗

PubMed1995

Association between duration of neonatal hospital stay and readmission rate.

OBJECTIVE: A recent rapid decrease in the duration of neonatal hospital stay in Ontario, Canada, enabled us to study the association between healthy infants' age at neonatal hospital discharge and subsequent readmission rates. DESIGN: (1) Population-based and (2) single hospital-based retrospective studies. SETTING AND STUDY POPULATION: (1) A total of 920,554 healthy infants with a birth weight of 2500 gm or more, born in Ontario from 1987 to 1994. (2) Infants with a birth weight of 2500 gm or more, born during the same period, and readmitted before 15 days from home to the Hospital for Sick Children for jaundice or dehydration. MEASUREMENT: Duration of neonatal stay in the hospital and readmission rates were measured, and diagnostic codes were analyzed. Severity of illness was evaluated in infants readmitted to our hospital. RESULTS: In Ontario the mean length of stay decreased from 4.5 days to 2.7 days (p = 0.000), and the readmission rate during the first 2 weeks of life increased from 12.9 to 20.7 per 1000 (p = 0.000). Increased rates of readmission were most marked for jaundice and dehydration. The infants readmitted to our hospital had evidence of increased severity of illness as indicated by higher serum bilirubin and sodium concentrations. Two deaths occurred in infants with hypernatremic dehydration, one in 1992-1993 and another in 1993-1994. CONCLUSIONS: In Ontario, shorter neonatal hospital stay was associated with increased readmission rates for conditions that may not give rise to symptoms or signs on days 1 to 3 of life. In our hospital the severity of jaundice and dehydration in readmitted infants increased. The severity-of-illness data raise the question of whether shorter neonatal hospital stay of apparently healthy infants is always safe. Decisions to discharge infants should be based on rigorous evaluation of individual infants.

Analysis of Variance↗

PubMed1995

Postoperative physical therapy after coronary artery bypass surgery.

Coronary artery bypass surgery is frequently complicated by postoperative atelectasis. Although routinely prescribed, the efficacy of any specific chest physical therapy is not well established. We studied patients at a university center undergoing elective coronary artery bypass surgery. Based upon chest X-ray criteria at extubation, patients (n = 228) were classified as demonstrating greater or lesser degrees of atelectasis. Those with a lesser degree of atelectasis were randomized to receive either early mobilization or sustained maximal inflations (SMI). Those with greater a degree of atelectasis were separately randomized to receive either SMI or single-handed percussions (SSP). We found the extent of atelectasis at extubation did not predict the risk of developing pneumonia. Hospital stays and intensive care unit stays were similar regardless of treatment. Physical therapy costs were highest in the most labor-intensive therapy group (SSP). We conclude that postoperative respiratory dysfunction is common but does not commonly cause significant morbidity or prolong hospital stay. Adding SMI to patients with minimal atelectasis at extubation does not improve clinical outcomes. Similarly, adding SSP to patients with marked atelectasis does not improve outcomes over those obtained with SMI and early ambulation.

Aged↗

PubMed1995

Appropriateness of adjuvant systemic therapy for axillary node-negative breast cancer: a physician opinion survey.

PURPOSE: To examine variations in physicians' recommendations for systemic adjuvant therapy in the treatment of women with node-negative breast cancer (NNBC) and to determine factors used in making specific recommendations. MATERIALS AND METHODS: A questionnaire was sent by mail to all 149 Ontario physicians who actively treated breast cancer in 1993. The questionnaire described 48 clinical scenarios of women with NNBC, which included all possible combinations of the following factors: menopausal status, tumor size, hormone receptor status, histologic and nuclear grade, and lymphatic and/or vascular invasion. Respondents rated the appropriateness of administering tamoxifen, combination chemotherapy, or both tamoxifen and combination chemotherapy on a nine-point scale from extremely inappropriate to extremely appropriate. Respondent agreement and disagreement were tabulated for each scenario, and factors associated with specific treatment ratings were analyzed by logistic regression. RESULTS: The response rate was 87%. Agreement for the appropriateness of specific therapies was most evident where clinical trials have demonstrated efficacy, whereas disagreement was observed in scenarios in which support for a specific treatment is not available in the current literature. Relevant tumor- and patient-specific factors were used in decision-making; personal characteristics of the respondents had no statistically significant impact on appropriateness ratings. CONCLUSION: The physicians surveyed had good knowledge of NNBC prognostic factors, but had a range of opinion on optimal therapy for many clinical scenarios, which reflects current knowledge of the benefits of adjuvant therapy for NNBC.

Adult↗

PubMed1995

Orchidectomy and hormonal therapy of prostate cancer.

The objective of this study is to document the use of hormonal therapies in treating prostate cancer in Ontario in the last decade. Drug utilization data were extracted from the Ontario Drug Benefit Program, while surgical orchidectomy rates were calculated from Hospital Medical Records Institute data. The provincial rate of orchidectomy showed a 55% relative increase from 1981 to 1991. There was a 6.4-fold variation in orchidectomy rates among counties in Ontario. As well, the expenditures on new hormonal therapies rose 38-fold between 1985 and 1990, and doubled between 1990 and 1992. There was no consistent relationship between use of orchidectomy and hormonal drug therapy at the county level. We conclude that both forms of hormonal therapy have increased in Ontario. The wide variation in surgical orchidectomy rates observed in Ontario suggests differences in practice styles and possible medical uncertainty. Guidelines for the hormonal therapy of prostate cancer may be a helpful step forward for practitioners and patients.

Journal Article↗

PubMed1994

Premorbid diet and the prognosis of women with breast cancer.

BACKGROUND: Consumption of a high-fat diet has been associated with poor survival in breast cancer patients. However, studies examining this association are limited and have not used adjustment of energy in their estimates. PURPOSE: The effect of usual diet before diagnosis of breast cancer on the risk of dying of breast cancer was examined in a cohort of women with breast cancer from the National Breast Screening Study (NBSS) in Canada. METHODS: From a cohort of 89,835 women in the NBSS, a total of 1270 histologically confirmed cases of invasive carcinoma of the breast were identified by active follow-up, supplemented by passive follow-up involving record linkage to provincial cancer registries. Of these, 678 case patients who had completed a diet history and were diagnosed from January 1982 up to June 1992 formed the cohort for this investigation. Diet was ascertained from a self-administered diet-history questionnaire. Mortality data were obtained by linkage to the Canadian Mortality Data Base of Statistics Canada, provincial cancer registries, and annual follow-up of cases through physicians. Risk of dying and survival probabilities were estimated by the Cox proportional hazards method and the actuarial life-table method. RESULTS: There were 83 deaths in this study cohort of 678 women; 76 deaths were due to breast cancer, and the remaining seven resulted from other causes. The 5-year survival rate was 90%. For every 5% increase in energy from saturated fat, the risk of dying of breast cancer increased by 50% (hazard ratio = 1.50; 95% confidence interval [CI]: 1.08-2.08). No significant increase in risk was seen with total fat intake (hazard ratio = 1.21; 95% CI = 0.91-1.61) or oleic acid intake (hazard ratio = 1.25; 95% CI = 0.90-1.74). There was a lower risk of dying of breast cancer in the highest quartiles of beta carotene intake (hazard ratio = 0.48; 95% CI = 0.23-0.99) and vitamin C intake (hazard ratio = 0.43; 95% CI: 0.21-0.86); both vitamins showed a significant dose-response relationship (P for trend, < or = .05). These effects varied with menopausal status at diagnosis and tumor characteristics. CONCLUSIONS: These results suggest an increased risk of dying of breast cancer with higher intakes of saturated fat before diagnosis and slightly reduced risk with higher intakes of beta carotene and vitamin C. IMPLICATIONS: More attention should be paid to premorbid dietary habits in relation to breast cancer prognosis. Further studies, however, need to be done with full ascertainment of dietary changes prior to and subsequent to diagnosis.

Adult↗

PubMed1994

Incidence and mortality from breast cancer in the Mama Program for Breast Screening in Finland, 1973-1986.

BACKGROUND: A cohort of women enrolled in the Mama breast self-examination-(BSE) containing breast screening program in Finland from 1973 through 1975 (with BSE used for screening and mammography for diagnosis) was studied. METHODS: Twenty-eight thousand seven hundred eighty-five women who returned calendars recording their practice of BSE over a 2-year period have been followed by linkage with the records of the Finnish Cancer Registry through 1986. The incidence of and mortality from breast cancer was compared with that expected in the Finnish population based on a model incorporating Finnish national data for breast cancer incidence and case fatality. RESULTS: Breast cancer incidence was higher than expected (a rate ratio of 1.19 over all ages). The stage distribution of cases was not different from that expected from Finnish cancer registry data for 1980, but the breast cancer mortality was lower than expected (a rate ratio of 0.75). The latter difference occurred mainly in Years 3-6 of the follow-up period. The effect seemed similar in women under and over the age of 50 years. The cohort was of higher educational status than the Finnish population, and the mortality from all causes was lower than the general Finnish population, an effect seen in previous studies of compliers with breast screening. CONCLUSIONS: The reduction in mortality from breast cancer in the study cohort is consistent with an effect of the BSE-containing Mama program, though selection bias, inherent in any observational study of screening, provided an alternative explanation for the findings.

Adult↗

PubMed1994

Cancer risks associated with occupational exposure to magnetic fields among electric utility workers in Ontario and Quebec, Canada, and France: 1970-1989.

To determine whether occupational exposure to magnetic fields of 50-60 Hz was associated with cancer among electric utility workers, the authors used a case-control design nested within three cohorts of workers at electric utilities: Electricité de France--Gaz de France, 170,000 men; Ontario Hydro, 31,543 men; and Hydro-Québec, 21,749 men. During the observation period, 1970-1989, 4,151 new cases of cancer occurred. Each participant's cumulative exposure to magnetic fields was estimated based on measurements of current exposure of 2,066 workers performing tasks similar to those in the cohorts using personal dosimetry. Estimates were also made of past exposure based on knowledge of current loading, work practices, and usage. Workers who had more than the median cumulative exposure to magnetic fields (3.1 microtesla (microT)-years) had a higher risk for acute nonlymphoid leukemia (odds ratio (OR) = 2.41, 95% confidence interval (CI) 1.07-5.44). The same observation holds for acute myeloid leukemia (OR = 3.15, 95% CI 1.20-8.27). There was also an elevated risk for mean exposure above 0.2 microT (acute nonlymphoid leukemia, OR = 2.36, 95% CI 1.00-5.58; acute myeloid leukemia, OR = 2.25, 95% CI 0.79-6.46). However, there were no clear dose-response trends with increasing exposure and no consistency among the three utilities. Men whose cumulative exposure to magnetic fields was above the 90th percentile (15.7 microT-years) had an elevated risk for brain cancer (OR = 1.95, 95% CI 0.76-5.00) that was not statistically significant. No association with magnetic fields was observed for any of the other 29 types of cancer studied, including skin melanoma, male breast cancer, and prostate cancer. Controlling for potential confounding factors did not change the results.

Aged↗

PubMed1994

Endothelial cell adhesion molecules in psoriasis.

Skin biopsies from patients with psoriasis and normal controls were examined for the expression of cell adhesion molecules including intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule-1 (ELAM-1), HECA-452 and 4D10, using an immunoperoxidase techique. This study demonstrates that psoriatic skin exhibits a wide variety of markers of endothelial cell activation which are either induced or increased in expression (ICAM-1, ELAM-1 & 4D10). Moreover, ICAM-1 & HECA-452 are also expressed on leukocytes. These antigens may facilitate the adhesion of inflammatory cells to endothelium and antigen-presenting cells in psoriatic skin. Thus, they may play a role in faciliating the infiltration of leukocytes into psoriatic skin.

Adult↗

PubMed1994

Pulmonary vascular effects of endotoxin in canine lobes pretreated with dapsone.

Endotoxin results in a granulocyte mediated loss of hypoxic pulmonary vasoconstriction (HPV). Dapsone blocks the granulocyte respiratory burst and might, therefore, preserve HPV following endotoxin. Isolated-perfused canine lobes (n = 6) were pretreated with 18 mg/kg dapsone (dapsone group), and compared to six lobes which did not receive dapsone (control group). Total pulmonary vascular resistance (Rtot) and arterial, middle (Rm), and venous segmental resistances were calculated by a vascular occlusion technique. We then administered endotoxin (2 mg/kg) and repeated measurements at 5, 30, and 90 min. The increase in Rm during 3% O2 compared to 35% O2 ventilation was used to define the presence of HPV. In the control group, following endotoxin, values of Rm did not change (P > 0.05) during 3% O2 ventilation (0.011 +/- 0.006 cm H2O/ml/min) compared with 35% O2 ventilation (0.014 +/- 0.005 cm H2O/ml/min). In the dapsone group, following endotoxin, values of Rm increased (P < 0.05) during 3% O2 ventilation (0.06 +/- 0.026 cm H2O/ml/min) compared with 35% O2 ventilation (0.03 +/- 0.015 cm H2O/ml/min). Changes in 6-keto PGF1 alpha or thromboxane B2 do not explain these observations. We conclude that in this experimental preparation, pretreatment with dapsone prevents the loss of HPV associated with endotoxin.

Animals↗

PubMed1993

Mammography.

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Breast Neoplasms↗

PubMed1993

NG-monomethyl-L-arginine does not restore loss of hypoxic pulmonary vasoconstriction induced by TNF-alpha.

Tumor necrosis factor-alpha (TNF-alpha) causes systemic hypotension, pulmonary vasodilation, and loss of hypoxic pulmonary vasoconstriction. NG-monomethyl-L-arginine (L-NMMA) inhibits nitric oxide (NO) production and prevents some systemic manifestations of TNF-alpha. We tested using an isolated perfused canine lobe whether NO also mediates the pulmonary vascular effects of TNF-alpha. Total resistance (RT) was measured during control and hypoxic ventilation over a 90-min period in six control lobes, five lobes treated with TNF-alpha (250 micrograms), six lobes treated with L-NMMA (200 mg), and five lobes treated with L-NMMA (200 mg) + TNF-alpha (250 micrograms). In the control lobes RT increased (P < 0.02) from 0.0474 +/- 0.0105 to 0.0677 +/- 0.0133 cmH2O.ml-1 x min during normoxic and hypoxic ventilation, respectively. RT decreased (P < 0.05) from a baseline of 0.0593 +/- 0.0133 to 0.0449 +/- 0.0176 cmH2O.ml-1 x min 30 min after TNF-alpha administration and did not further change during hypoxic ventilation (0.0475 +/- 0.0107 cmH2O.ml-1 x min). L-NMMA pretreatment did not prevent the TNF-alpha-induced loss of hypoxic pulmonary vasoconstriction, with values of RT unchanged from normoxic (0.0541 +/- 0.0067 cmH2O.ml-1 x min) to hypoxic (0.0545 +/- 0.0078 cmH2O.ml-1.min) ventilation (P > 0.10) in the L-NMMA + TNF-alpha group after TNF-alpha administration. We conclude that NO is not the mediator responsible for the acute pulmonary vascular effects of TNF-alpha.

Animals↗

PubMed1992

Canadian National Breast Screening Study: 1. Breast cancer detection and death rates among women aged 40 to 49 years.

OBJECTIVES: To evaluate the efficacy of the combination of annual screening with mammography, physical examination of the breasts and the teaching of breast self-examination in reducing the rate of death from breast cancer among women aged 40 to 49 years on entry. DESIGN: Individually randomized controlled trial. SETTING: Fifteen urban centres in Canada with expertise in the diagnosis and treatment of breast cancer. PARTICIPANTS: Women with no history of breast cancer and no mammography in the previous 12 months were randomly assigned to undergo either annual mammography and physical examination (MP group) or usual care after an initial physical examination (UC group). The 50,430 women enrolled from January 1980 through March 1985 were followed for a mean of 8.5 years. DATA COLLECTION: Derived from the participants by initial and annual self-administered questionnaires, from the screening examinations, from the patients' physicians, from the provincial cancer registries and by record linkage to the Canadian National Mortality Data Base. Expert panels evaluated histologic and death data. MAIN OUTCOME MEASURES: Rates of referral from screening, rates of detection of breast cancer from screening and from community care, nodal status, tumour size, and rates of death from all causes and from breast cancer. RESULTS: Over 90% of the women in each group attended the screening sessions or returned the annual questionnaires, or both, over years 2 to 5. The characteristics of the women in the two groups were similar. Compared with the Canadian population, the participants were more likely to be married, have fewer children, have more education, be in a professional occupation, smoke less and have been born in North America. The rate of screen-detected breast cancer on first examination was 3.89 per 1000 in the MP group and 2.46 per 1000 in the UC group; more node-positive tumours were found in the MP group than in the UC group. During years 2 through 5 the ratios of observed to expected cases of invasive breast cancer were 1.26 in the MP group and 1.02 in the UC group. Of the women with invasive breast cancer through to 7 years, 191 and 157 women in the MP and UC groups respectively had no node involvement, 55 and 43 had one to three nodes involved, 47 and 23 had four or more nodes involved, and 38 and 49 had an unknown nodal status. There were 38 deaths from breast cancer in the MP group and 28 in the UC group. The ratio of the proportions of death from breast cancer in the MP group compared with those in the UC group was 1.36 (95% confidence interval 0.84 to 2.21). The survival rates were similar in the two groups. The highest survival rate occurred among women whose cancer had been detected by mammography alone. CONCLUSION: The study was internally valid, and there was no evidence of randomization bias. Screening with yearly mammography and physical examination of the breasts detected considerably more node-negative, small tumours than usual care, but it had no impact on the rate of death from breast cancer up to 7 years' follow-up from entry.

Adult↗

PubMed1992

Canadian National Breast Screening Study: 2. Breast cancer detection and death rates among women aged 50 to 59 years.

OBJECTIVE: To evaluate the efficacy of annual mammography over and above annual physical examination of the breasts and the teaching of breast self-examination among women aged 50 to 59 on entry. DESIGN: Individually randomized controlled trial. SETTING: Fifteen urban centres in Canada with expertise in the diagnosis and treatment of breast cancer. PARTICIPANTS: Women with no history of breast cancer and no mammography in the previous 12 months were randomly assigned to undergo either annual mammography and physical examination (MP group) or annual physical examination only (PO group). The 39,405 women enrolled from January 1980 through March 1985 were followed for a mean of 8.3 years. DATA COLLECTION: Derived from the participants by initial and annual self-administered questionnaires, from the screening examinations, from the patients' physicians, from the provincial cancer registries and by record linkage to the Canadian National Mortality Data Base. Expert panels evaluated histologic and death data. MAIN OUTCOME MEASURES: Rates of referral from screening, rates of detection of breast cancer from screening and from community care, nodal status, tumour size and rates of death from all causes and from breast cancer. RESULTS: Over 85% of the women in each group attended the screening sessions after screen 1. The characteristics of the women in the two groups were similar. Compared with the Canadian population the participants were more likely to be married, have fewer children, have more education, be in a professional occupation, smoke less and have been born in North America. The rate of screen-detected breast cancer on first examination was 7.20 per 1000 in the MP group and 3.45 per 1000 in the PO group, more node-positive tumours were found in the MP group than in the PO group. At subsequent screens the detection rates were a little less than half the rates at screen 1. During years 2 through 5 the ratios of observed to expected cases of invasive breast cancer were 1.28 in the MP group and 1.18 in the PO group. Of the women with invasive breast cancer through to 7 years, 217 in the MP group and 184 in the PO group had no node involvement, 66 and 56 had one to three nodes involved, 32 and 34 had four or more nodes involved, and 55 and 46 had an unknown nodal status. There were 38 deaths from breast cancer in the MP group and 39 in the PO group. The ratio of the proportions of death from breast cancer in the MP group compared with those in the UC group was 0.97 (95% confidence interval 0.62 to 1.52). The survival rates were similar in the two groups. Women whose cancer had been detected by mammography alone had the highest survival rate. CONCLUSION: The study was internally valid, and there was no evidence of randomization bias. Screening with yearly mammography in addition to physical examination of the breasts detected considerably more node-negative, small tumours than screening with physical examination alone, but it had no impact on the rate of death from breast cancer up to 7 years' follow-up from entry.

Breast Neoplasms↗

PubMed1992

Risk of breast cancer in women with breast cysts.

OBJECTIVE: To study the occurrence of breast cancer in women with breast cysts. DESIGN: Prospective follow-up study. SETTING: Office surgical practice. PATIENTS: All 742 women referred to the practice with breast cysts diagnosed by means of aspiration or, occasionally, biopsy between 1969 and 1985. MAIN OUTCOME MEASURES: The incidence of breast cancer and the number of years between diagnosis of breast cyst and diagnosis of cancer. The observed number of cases of breast cancer was compared with the expected number, calculated from Ontario rates of breast cancer. RESULTS: Fifteen of the women died but did not have breast cancer. No follow-up information was available for five women. Another 38 were lost to follow-up; they did not have breast cancer at the last contact, after 2 to 17 years of follow-up. These patients were withdrawn from the study in the year in which they died or were last observed. By 1990, 34 (5%) of the women had breast cancer. The overall ratio of observed:expected cases of cancer was 3.04 (95% confidence interval 2.09 to 4.28). Breast cancer developed after 7.5 years, but the average length of follow-up was only 10.1 years. Only 3.8% of 374 women after 10 years and 5.4% of 141 women after 15 years had breast cancer. CONCLUSION: Women who have a gross breast cyst are at moderately increased risk of breast cancer, which usually develops only after many years.

Adolescent↗

PubMed1992

Prostacyclin (not nitroprusside) preserves venous admixture in the injured canine lung.

OBJECTIVE: To compare the effects of a prostaglandin vasodilator (prostaglandin I2 [PGI2]) with that of sodium nitroprusside in the isolated lung during 3% and 35% oxygen ventilation. BACKGROUND AND METHODS: Pulmonary vascular resistance was divided into arterial, middle, and venous segmental resistances. Left lower lobes were injured in a patchy (atelectasis) or diffuse (oleic acid-induced edema) manner. RESULTS: Nitroprusside diminished, but PGI2 ablated, the usual increase in middle segment resistance observed during 3% oxygen ventilation in atelectatic lobes. In the oleic acid-treated lobes, both nitroprusside and PGI2 ablated the increase in middle segment resistance during 3% oxygen ventilation. During nitroprusside administration, as pulmonary vascular resistance decreased, venous admixture proportionately increased, but this correlation was lost during PGI2 administration. CONCLUSIONS: We hypothesize that exogenous PGI2 dilates the vessels most constricted by hypoxia but to a lesser degree than does nitroprusside. Therefore, increases in venous admixture may be reduced during PGI2 administration, compared with nitroprusside administration.

Animals↗

PubMed1992

Interactions of endotoxin, prostaglandins, and circulating cells upon pulmonary vascular resistance.

We studied the effects of endotoxin on total pulmonary vascular resistance (PVR) and hypoxic pulmonary vasoconstriction (HPV) in 24 isolated canine lung lobes. Group 1 lobes were perfused with whole blood; group 2 lobes with granulocyte/platelet depleted blood; group 3 lobes with whole blood and ibuprofen (12.5 mg/kg); group 4 lobes with granulocyte/platelet depleted blood and ibuprofen (12.5 mg/kg). All groups were otherwise treated in a similar manner and all received endotoxin (1 mg/kg) after baseline periods of normoxic and hypoxic ventilation. We found endotoxin increased PVR by 18% in group 1 and by 41% in group 2. Endotoxin administration inhibited HPV in group 1 but did not inhibit HPV in group 2. Ibuprofen administration prevented the increase in PVR and the loss of HPV caused by endotoxin. We conclude that endotoxin administration causes release of a lung-derived vasoconstrictor, but this is obscured by concomitant release of a granulocyte/platelet associated vasodilator. Our data also suggest that granulocytes or platelets may modulate baseline PVR by producing a nonprostaglandin vasodilator.

Animals↗