Biomedical subjects

R Johnston

Publications and source records attributed to R Johnston.

At least 55 records · Page 3Linked to original sources

PubMed1996

Unusual complications of cervical spine surgery for cervical myelopathy in rheumatoid arthritis.

Cervical myelopathy is a recognized complication of rheumatoid arthritis and other inflammatory arthropathies. In a significant proportion of patients, surgical stabilization of the cervical spine offers the best opportunity for improvement of symptoms and long-term survival. We report two cases that illustrate some potential complications of cervical spine surgery and which also emphasize the need for vigilance when caring for patients in this group.

Arthritis, Rheumatoid↗

PubMed1996

Cost accounting of adult intensive care: methods and human and capital inputs.

OBJECTIVE: To cost adult intensive care by determining inputs to production, resource consumption per patient, and total cost per intensive care unit (ICU) stay. DESIGN: Prospective cost-accounting analysis of each patient stay in the ICU, over a 1-yr period. SETTING: An 11-bed, medical/surgical adult ICU, in a 932-bad urban teaching hospital. PATIENTS: All patients' admissions to an adult ICU over a 1-yr period, excluding those patients admitted solely for repeat hemodialysis. INTERVENTIONS: None. MEASUREMENT AND MAIN RESULTS: Demographic information was collected, including age, gender, Acute Physiology and Chronic Health Evaluation (APACHE) II score, primary reason for ICU admission, operative (elective and emergency) and nonoperative status, ICU length of stay, and ICU outcome. Direct patient care costs were accounted to individual patients whose care generated those costs, and indirect patient care costs were averaged over all patients in the ICU on a daily basis. Costs were collected for human (nursing, medical, professional, and support staff) and capital (laboratory, diagnostic imaging, supplies, drugs, and equipment) resources. Cost information was available on 690 patients (43% female, 57% male). Cost/day/patient was $1,508 +/- 475 (1992 Canadian dollars) and the average cost per ICU stay was $7,520 +/- 11,606. Median cost/stay for all patients was $2,600. Cost per ICU stay was < $5,000 in 68% of patients, with an ICU survival rate of 85%. High cost was not a marker for poor survival. There was no relationship between age and cost categories. Across most diagnoses, cost/ day/patient was remarkably constant, approximating $1,500/day/ patient at existing labor rates. CONCLUSIONS: In order to develop strategies aimed at cost containment, it is first necessary to undertake a thorough examination of cost drivers. This detailed cost-accounting study determined inputs to production, resources consumed by individual patients, and costs incurred during ICU stay.

APACHE↗

PubMed1996

The role of computer-based simulation for training surgeons.

The effectiveness of computer based simulation (CBS) technology for training surgeons has yet to be determined. However, there is a body of research that demonstrates the effectiveness of this technology for other training applications. This research also indicates the substantial savings in cost, time, and effectiveness of simulation.

Clinical Competence↗

PubMed1996

Assessing a virtual reality surgical skills simulator.

The Institute for Defense Analyses (IDA) was contracted to perform a military standard task analysis of laparoscopic cholecystectomy, and to study the effectiveness of a virtual reality surgical skills simulator as a tool for surgical training and as a method for recording psychomotor behavior. This report describes the purpose of the study, its design, initial results, and implications for the field of medical education.

Cholecystectomy, Laparoscopic↗

PubMed1996

DNA sequencing by capillary electrophoresis with a hydroxyethylcellulose sieving buffer.

Capillary electrophoresis (CE) is capable of rapid, high-resolution separations of DNA. The technique has been adopted for both ssDNA and dsDNA applications. In order to make CE more convenient and cost-effective, replaceable sieving buffers have recently been developed. For DNA sequencing, the most successful of these replaceable buffers have been carefully polymerized and purified viscous linear polyacrylamide solutions. However, the hazards of acrylamide are well documented, and the care required to prepare the appropriate molecular weight polymer make this approach less than ideal. We report use of a replaceable sieving buffer suitable for DNA sequencing by CE that is easy to prepare and uses commercially available, non-toxic hydroxyethylcellulose.

Buffers↗

PubMed1995

Quality of life measures before and one year after admission to an intensive care unit.

OBJECTIVE: To assess outcome of patients admitted to an intensive care unit (ICU), using a prospective 1-yr follow-up, with special emphasis on various quality of life measures before and after admission to the ICU. DESIGN: Prospective comparison of quality of life before and 1 yr after admission to the ICU. SETTING: Eleven-bed adult medical/surgical ICU. PATIENTS: All patients admitted to the ICU over a 1-yr period were eligible for inclusion in this study. Repeat admissions were enrolled only on first admission. Patients < 17 yrs of age and those patients who died within 24 hrs of admission were excluded. INTERVENTIONS: Quality of life measures were collected before and 6 and 12 months after ICU admission. MEASUREMENTS AND MAIN RESULTS: The following data were collected: duration of ICU and hospital stay; ICU, hospital, 6- and 12-month mortality; quality of life (level of activity, activities of daily living, perceived health, support, and outlook on life) and place of residence at baseline and 12 months after ICU admission. There were 504 patients who met the study criteria; age 55 +/- 20 yrs (median 59), 229 female and 275 male. Mean ICU length of stay was 4.3 +/- 7.4 days. Hospital length of stay was 31 +/- 41 days. Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 14 +/- 7. Cumulative mortality: ICU 5.4%, hospital 13.5%, 6 month 20.6%, and 12 month 25%. One year quality of life questionnaires were completed for 293 patients. Relative to baseline, there was a decrease in the level of activity and activities of daily living at 12 months (p < .01). Perceived health status increased over the year for patients > or = 75 yrs of age (p < .01). There was no difference in the level of support from family or friends, or outlook on life, at 12 months. At 1 yr, 262 (89%) patients were living at home. CONCLUSION: Patients admitted to intensive care tend to have a decrease in the level of activity and activities of daily living 1 yr after their ICU stay, although in the very elderly, perceived health status increases. As well, the majority (89%) of patients return home.

Activities of Daily Living↗

PubMed1995

Ability of spermatozoa to bind to the zona pellucida during oligozoospermia induced with testosterone during a male contraceptive trial.

To determine the ability of spermatozoa to bind to the zona pellucida (ZP) in testosterone-induced oligozoospermia, previously fertile men participating in the World Heath Organization (WHO) male contraceptive trial in Melbourne were studied while oligozoospermic to various degrees. Semen analysis were performed according to WHO methods. One or two ejaculates from each subject were cryopreserved before commencing weekly intramuscular injections of 200 mg testosterone enanthate. The frozen spermatozoa were used as controls for ZP-binding tests of spermatozoa obtained during testosterone-induced oligozoospermia (< 10 x 10(6)/ml) in either the suppression or efficacy (n = 6) and recovery (n = 3) phases. Two other subjects in the recovery phase with normozoospermia were also tested. Human oocytes that failed to fertilized in vitro from infertile patients were used for the sperm-ZP binding test. Control (frozen) spermatozoa were labelled with fluorescein isothiocyanate and test (oligozoospermic semen) spermatozoa were labelled with tetramethylrhodamine B isothiocyanate. A mixture of equal numbers of labelled motile control and test spermatozoa were incubated with 4-6 ZP. There was a significantly (p < 0.01) lower number of spermatozoa bound per ZP in oligozoospermic samples (65 +/- 7, mean +/- SEM) than in controls (80 +/- 7). However, there were still large numbers of spermatozoa bound to the ZP for all the oligozoospermic samples. Five subjects had similar numbers of spermatozoa bound to the ZP for both control and oligozoospermic samples. Overall, the ZP-binding ratio of test and control spermatozoa averaged 0.82 (range 0.51-1.13).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Forehead and forearm skin blood flows in newborn infants measured by laser Doppler flowmetry: short-term variability and relationship to sleep states.

Laser doppler flowmeters were used to measure blood flow in the skin of the forehead and volar surface of the forearm of infants at 2-9 days of age, and at 8-12 weeks of age. At both ages mean skin blood flow was higher during active sleep compared to quiet sleep. In infants up to 9 days of age, mean skin blood flow was higher in forehead skin compared to forearm skin. Skin blood flow was highly variable at both recording sites, and was significantly higher and more variable during active compared to quiet sleep in the forehead, but not in the forearm. The results indicate that recordings of skin blood flow over at least two cycles of active and quiet sleep are needed to describe the normal variation with sleep state. The factors which regulate forehead and forearm skin blood flows may differ in importance between the two sites, perhaps reflecting the different thermoregulatory importance of cutaneous blood flow in the forehead and forearm.

Forearm↗

PubMed1994

The influence of age, diagnosis, and gender on proper use of metered-dose inhalers.

Metered dose inhalers (MDIs) are widely used in clinical practice for administering pharmaceuticals targeted to the lung. It is well known that the inhalation technique used with MDIs can substantially influence the clinical response to inhaled medications. To determine the acceptability of MDI maneuvers, we studied 59 subjects (26 females and 33 males; age, 20 to 81 yr; mean age, 38 yr) to determine whether the MDI technique used by these individuals complied with published recommendations for acceptable inhalation technique. Measurements were made with an MDI adapter that contained an unobtrusive, lightweight, miniature sensing system. Inspiratory flow at the moment of MDI actuation (Va), the volume (integrated from airflow) at actuation as a fraction of total inspiratory volume (Va/VI), breath-holding time (tBH), and inspiratory volume as a fraction of FVC (VI/FVC) were determined from 59 uncoached inhalations. We defined an acceptable maneuver, based on published data, by four components: (1) inspiratory flow at actuation (Va) between 25 and 90 L/min; (2) actuation during early inspiration (0 < Va/VI < or = 0.20); (3) adequate breath-holding time (tBH > 4 s), and (4) a deep inhalation (VI/FVC > 0.50). For all subjects, only 25% of inhalation maneuvers met all four criteria for acceptability. We found that a significantly higher proportion of male than female subjects performed an acceptable MDI maneuver (43% versus 4%, p < 0.001). There were no significant differences in technique between younger and older subjects or between patients with a diagnosis of asthma or chronic obstructive pulmonary disease (COPD). We conclude that most patients use their MDIs incorrectly; females of all ages are much more likely to have improper MDI technique than are males.

Adult↗

PubMed1994

On the ground at the U.S. Air Show.

Careful planning and organization at mass gatherings are essential if adequate medical care is to be ensured. The U.S. Air Show in Dayton, Ohio, attracts thousands of spectators annually and requires that dozens of EMS agencies and hundreds of first responders, EMTs, paramedics, nurses and physicians join forces to provide EMS coverage.

Accidents, Aviation↗

PubMed1994

Evaluation of autologous shed blood for autotransfusion after orthopaedic surgery.

Autologous shed blood for autotransfusion was evaluated at four medical centers in a prospective randomized study. One hundred twenty-eight patients were studied after hip replacement, knee replacement, or spine fusion. The efficacy of autologous shed blood in reducing homologous transfusion was evaluated. The relative risk of transfusion with homologous blood was 0.4 in patients who received shed blood compared with patients who did not receive shed blood. The reinfusion of shed blood reduced the requirement for homologous blood by 60%. Two filter systems were evaluated in reinfusing autologous shed blood. The Pall RC100 filter appeared to be more effective than the Pall 40-mu screen filter in removing fat particles and white blood cells. No significant clinical abnormalities were discovered after autotransfusion with autologous shed blood. Evaluation of clotting studies showed no significant differences between patients who received shed blood and patients who received liquid-preserved red blood cells. These data indicate that unwashed autologous shed blood from orthopaedic wound drainage is a safe and effective substitute for transfusion of autologous predonated blood or homologous liquid-preserved red blood cells.

Adult↗

PubMed1993

Regulation of human lung fibroblast alpha 1(I) procollagen gene expression by tumor necrosis factor alpha, interleukin-1 beta, and prostaglandin E2.

We investigated the participation of prostaglandin (PG) E2 in the regulation of the alpha 1(I) procollagen gene expression by tumor necrosis factor alpha (TNF alpha), and interleukin-1 beta (IL-1 beta) in normal adult human lung fibroblasts. TNF alpha (100 units/ml) and IL-1 beta (100 units/ml) stimulated the production of PGE2 and caused a dose-dependent inhibition of up to 54 and 66%, respectively, of the production of type I procollagen. Preincubation of cultures with indomethacin partially reversed the inhibition of procollagen production induced by the cytokines. Cytokine-stimulated endogenous fibroblast PG accounted for 35 and 68% of the inhibition induced by TNF alpha and IL-1 beta, respectively. Steady-state mRNA levels for alpha 1(I) procollagen paralleled the changes in collagen production. The transcription rate of the alpha 1(I) procollagen gene was reduced by 58% by TNF alpha and by 43% by IL-1 beta. Cytokine-stimulated endogenous PG production accounted for half of these effects. These results indicate that TNF alpha and IL-1 beta inhibit the expression of the alpha 1(I) procollagen gene in human lung fibroblasts at the transcriptional level by a PGE2-independent effect as well as through the effect of endogenous fibroblast PGE2 released under the stimulus of the cytokines.

Adult↗

PubMed1993

One-year outcome of elderly and young patients admitted to intensive care units.

OBJECTIVE: To compare the outcome of patients over and under age 65 admitted to two intensive care units (ICUs). DESIGN: Prospective, two-center study. Convenience sample of all admissions to two adult ICUs for a 1-yr period, with a 1-yr follow-up. SETTING: Adult multidisciplinary closed ICUs. PATIENTS: All patients (n = 1,040) admitted to two ICUs during a 1-yr period were entered into the study, except patients with self-induced poisoning. Of these patients, 145 patients were lost to follow-up. INTERVENTIONS: Admission statistics on all patients included demographic, case mix, and severity data. Variables associated with intensive care unit outcomes at discharge (length of stay, mortality) and at 1 yr from admission (mortality, functional capacity, health attitudes) were analyzed. Vital status was confirmed from both Alberta Vital Statistics and Alberta Health. Follow-up interviews were conducted with all available survivors. RESULTS: The elderly group (> 65 yrs) comprised 46% of patients studied. Both age groups (> 65 yrs and < 65 yrs) had comparable demographics and illness severity measures. Although ICU and 1-yr mortality rates differed between groups (16% of > 65 yrs vs. 12.9% of < 65 yrs ICU mortality and 49% of > 65 yrs vs. 31% of < 65 yrs 1-yr mortality), age was not a major contributor to the variance in outcome. At 1 yr, 65% of patients admitted to the study were alive. Follow-up interviews were conducted with 75% of survivors. Assessment of activities of daily living showed that the elderly patients were similar to younger patients. The elderly demonstrated more positive health attitudes than younger survivors. Functional capacity was significantly associated with health attitudes of younger patients, but not for older survivors. CONCLUSIONS: Age does not have an important impact on outcome from critical illness, which is most strongly predicted by severity of illness, length of stay, prior ICU admission and respiratory failure. Satisfaction with personal health should not be inferred from the functional status of elderly survivors of intensive care.

Activities of Daily Living↗

PubMed1993

Effects of alcohol, carbon tetrachloride, and choline deficiency on iron metabolism in the rat.

The effects of alcohol on hepatic iron uptake and intestinal iron transport were studied in rats fed a nutritionally replete liquid diet containing varying quantities of ethanol. Results were compared with those from animals exposed to carbon tetrachloride (CCl4) to produce hepatocellular necrosis or a choline-deficient diet to produce steatosis and cirrhosis. A high ethanol intake for 4 or 10 weeks produced hepatic steatosis. CCl4 produced hepatocellular necrosis. Choline deficiency was associated with steatosis +/- cirrhosis. Intestinal iron transport was unaffected by ethanol, CCl4, or choline deficiency. Hepatic iron uptake was significantly depressed in rats consuming 11.7 g/kg/day ethanol (p < 0.01) for 4 weeks. Choline-deficient animals studied at 14 weeks also had significantly decreased hepatic iron uptake (p < 0.01); results were similar in the cirrhotic and noncirrhotic animals. Conversely, CCl4 exposure produced a significant 5-fold increase in hepatic iron uptake (p < 0.001). Results suggest that ethanol consumption, fatty liver, and cirrhosis are not responsible for any increase in iron absorption or of hepatic iron uptake in the rat model. Acute hepatocellular injury is followed by increased hepatic iron uptake.

Animals↗

PubMed1993

Efficacy and safety of b.i.d. doses of venlafaxine in a dose-response study.

In this study, 312 depressed outpatients received either placebo or one of three venlafaxine doses twice daily (b.i.d.) for up to 6 weeks. The total daily doses of venlafaxine were 25, 50-75, and 150-200 mg/day. Hamilton Rating Scale for Depression (HAM-D) and Montgomery-Asberg Depression Rating Scale (MADRS) total scores at Week 6 were significantly lower for the high-dose group than for the placebo group. A positive dose-response trend for the primary efficacy parameters was demonstrated as early as Week 1. Venlafaxine was well tolerated at all dose levels. The most common side effects of clinical interest were nausea and dry mouth. The frequency of nausea in the venlafaxine groups was essentially the same (25-29%), whereas the frequencies of dry mouth, somnolence, and sweating were dose related. The results indicate that b.i.d. doses of venlafaxine are safe and effective in treating depression.

Adolescent↗

PubMed1992

Profile of selected bacterial counts and Salmonella prevalence on raw poultry in a poultry slaughter establishment.

The USDA Food Safety and Inspection Service determined populations of bacteria on poultry during processing at a slaughter plant in Puerto Rico in November and December 1987. The plant was selected because of its management's willingness to support important changes in equipment and processing procedures. The plant was representative of modern slaughter facilities. Eight-hundred samples were collected over 20 consecutive 8-hour days of operation from 5 sites in the processing plant. Results indicated that slaughter, dressing, and chilling practices significantly decreased the bacterial contamination on poultry carcasses, as determined by counts of aerobic bacteria, Enterobacteriaceae, and Escherichia coli. Salmonella was not enumerated; rather, it was determined to be present or absent by culturing almost the entire rinse. The prevalence of Salmonella in the study decreased during evisceration, then increased during immersion chilling.

Abattoirs↗

PubMed1992

Comparison of PT and aPTT values drawn by venipuncture and arterial line using three discard volumes.

BACKGROUND: Blood samples obtained through heparinized arterial catheters are used routinely for a variety of laboratory tests. Accuracy of coagulation studies performed from samples obtained in this fashion continues to be questioned, particularly in regard to the minimum discard volume necessary to clear the catheter of heparinized solution. OBJECTIVE: To examine differences between prothrombin time and activated partial thromboplastin time values obtained from blood drawn by venipuncture and from an indwelling intra-arterial line using three discard volumes. METHODS: Prothrombin time and activated partial thromboplastin time samples were drawn by venipuncture from 41 critically ill adult patients. Simultaneously, three consecutive blood samples of 2.3 mL were drawn from the arterial line after an initial discard volume of 3 mL (discard volumes of 3.0, 5.3 and 7.6 mL). RESULTS: Significant differences were found between arterial and venous prothrombin time values for the 3-mL discard volume group, as well as between arterial and venous activated partial thromboplastin time values for all three discard volume groups (paired t-test, Bonferroni correction). CONCLUSION: We recommend that when drawing prothrombin time and activated partial thromboplastin time samples from an arterial line, a 5.3-mL discard volume be used.

Adult↗

PubMed1992

Ulnar nerve decompression at the cubital tunnel.

A limited surgical decompression of the ulnar nerve within the cubital tunnel by incision of the arcuate ligament was effective in relieving pain and dysesthesia in 22 of 27 patients. No patient had any apparent muscle weakness or atrophy preoperatively. Twenty-five patients had evidence of compression of the ulnar nerve within the cubital tunnel at surgery, as noted by narrowing, hyperemia, or attachment of adhesions to the nerve. Three of four patients who had a subsequent anterior transposition obtained partial relief of symptoms.

Adult↗