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Biomedical subjects

J Colvin

Publications and source records attributed to J Colvin.

At least 19 recordsLinked to original sources
PubMed1997

Use of 2% propofol to produce diurnal sedation in critically ill patients.

OBJECTIVE: The assessment of propofol to produce diurnal sedation in critically ill patients. DESIGN: Prospective clinical study. SETTING: Intensive Care Unit, University Hospital. PATIENTS AND PARTICIPANTS: Thirty consecutive patients admitted to the Intensive Care Unit older than 18 years who were expected to be sedated for more than 50 h. INTERVENTIONS: The patients were randomised into two groups. All received sedation with a constant background infusion of morphine and a variable infusion rate of propofol, which was altered hourly to maintain the intended sedation score. The first group received constant light sedation (CLS) over 50 h aiming for a Ramsay score of 2-3. The second group received CLS between 0600 h and 2200 h and additional night sedation (ANS) with propofol between 2200 h and 0600 h, aiming for a sedation score of 4-5. MEASUREMENTS AND RESULTS: Patients were studied for 50 h from 1800 h on the first day of admission. Recordings of heart rate, blood pressure, sedation scores and propofol and morphine infusion rates were made hourly. An APACHE II score was recorded for each patient. Sedation scores were analysed by blind visual assessment and cosinor analysis, which is used in chronobiology to examine the correlation of data with a cosine curve. Patients in the ANS group had significantly better rhythmicity of sedation levels using cosinor analysis (r = 26% v 8%) p < 0.01. There was no difference between the CLS and ANS groups with respect to age, sex or APACHE II scores. Nine out of 15 patients in the ANS group achieved diurnal sedation. Three patients in the CLS group showed diurnal rhythmicity of sedation, which can be attributed to natural sleep, and had a median APACHE II score of 12. Five patients in the CLS group and three in the ANS group showed a deep constant sedation pattern. They had high APACHE II scores (median 21.5) and an obtunded conscious level on admission due to severe sepsis. CONCLUSION: Propofol can safely provide diurnal sedation in the critically ill when titrated against the Ramsay score. Sedation levels cannot be manipulated in some severely ill patients.

APACHE↗
PubMed1997

Propofol 2% in critically ill patients: effect on lipids.

OBJECTIVE: To investigate the concentrations of triglyceride, cholesterol, and high-density lipoprotein during a 50-hr infusion of 2% propofol, starting within 24 hrs of admission to the intensive care unit (ICU). DESIGN: Prospective, clinical study. SETTING: ICU, university hospital. PATIENTS: Thirty adult patients, who were ventilated and expected to be sedated for >2 days, were studied for 50 hrs, beginning at 1800 hrs on the first day of ICU admission. MEASUREMENTS AND MAIN RESULTS: Triglyceride, cholesterol, and high-density lipoprotein were measured at 2000, 0400, and 0800 hrs. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and C-reactive protein were measured at 2000 hrs. Median cholesterol and high-density lipoprotein concentrations were at the low end of the normal range. In seven patients, peak triglyceride concentrations were >3 mmol/L up to a maximum of 4.83 mmol/L. Although there was no statistical difference in lipid concentrations between days 1 and 2, there was an apparent pattern of increasing triglyceride concentrations. There was a correlation between peak triglyceride concentration and total propofol consumption, but there was no correlation between lipids and age, gender, or Acute Physiology and Chronic Health Evaluation II scores. There was a direct correlation between triglyceride and C-reactive protein concentrations, and an inverse correlation between cholesterol and C-reactive protein. Twenty-two patients had evidence of TNF and 11 patients had an IL-6 of >1000 pg/mL, but there was no relationship between concentrations of cytokines and triglycerides in plasma. CONCLUSIONS: Infusion of 2% propofol to critically ill patients over a 50-hr period does not result in a significant increase in triglyceride concentrations. Mean cholesterol and high-density lipoprotein concentrations were low throughout the study period. There was a significant direct correlation between triglyceride and C-reactive protein and an inverse correlation between cholesterol and C-reactive protein, suggesting that the changes in lipids in critically ill patients may be partly attributable to the acute-phase response.

APACHE↗
PubMed1995

Estimating intracellular pH in developing rodent embryos using a computer imaging technique: changes in embryonic pH and proliferation rates following maternal treatment with acetazolamide.

Using the transplacental distribution of the weak acid 5,5-dimethyloxazolidine-2,4-dione (DMO), a computer assisted imaging technique has been developed to permit the estimation of intracellular pH (pHi) in very specific areas of the developing rodent embryo. The study reported here demonstrates the heterogeneity of radiolabeled DMO distribution in the developing mouse forelimb. The pattern of pHi distribution shifts from one of high pHi values in the proximal core of the mesoderm on day 10 of gestation to one of higher pHi values in the mesoderm just underlying the ectoderm on day 11. Studies [Scott et al. (1990) Toxicol. Appl. Pharmacol. 103:238-254] in which DMO concentration was monitored following treatment with acetazolamide or acetazolamide plus amiloride were done in whole embryo homogenates or pooled limb samples which allow for the calculation of an average pHi but may not reflect the pHi in very specific locations of the limb. Two hours after acetazolamide administration, the pHi pattern was not significantly changed from control. Intracellular pH was raised above control levels but was not significant statistically except in the peripheral mesoderm in the ventral third of the forelimb. Fifteen hours after acetazolamide treatment, there was a significant decrease in pHi values with no change in pattern. However, treatment with acetazolamide plus amiloride for 15 hr produced a marked reduction of pHi values throughout the forelimb bud. Changes in bromodeoxyuridine labeling index (an indication of proliferative activity) following treatment with acetazolamide or acetazolamide plus amiloride are reported. The combination treatment reduced the labeling index by approximately 15% below that of control embryos in the limb region where absence of digit(s) will occur. However, we found no overall correlation of proliferative rate and pHi of limb bud mesoderm in treated embryos. Consequently, we were unable to causally associate reduced pHi with decreased proliferative rate.

Abnormalities, Drug-Induced↗
PubMed1995

Initial management and transport of patients with perforating eye injuries.

The first 24 hours are critical for a good surgical result from perforating eye injuries. The basic principles of initial management and transfer include prevention of vomiting, pain and infection, and avoidance of further injury. Where air transport is necessary it must be with the cabin altitude at sea level, or as low as is safe. Surgical repair should be undertaken as promptly as is practical.

Adult↗
PubMed1993

A high-field superferric NMR magnet.

Strong, extensive magnetic fringe fields are a significant problem with magnetic resonance imaging magnets. This is particularly acute with 4-T, whole-body research magnets. To date this problem has been addressed by restricting an extensive zone around the unshielded magnet or by placing external unsaturated iron shielding around the magnet. This paper describes a solution to this problem which uses superconducting coils closely integrated with fully saturated iron elements. A 4-T, 30-cm-bore prototype, based on this design principle, was built and tested. The 5 G fringe field is contained within 1 meter of the magnet bore along the z axis. Homogeneity of the raw magnetic field is 10 ppm over 30% of the magnet's diameter after passive shimming. Compared with an unshielded magnet, 20% less superconductor is required to generate the magnetic field. Images and spectra are presented to demonstrate the magnet's viability for magnetic resonance imaging and spectroscopy.

Magnetic Resonance Spectroscopy↗
PubMed1989

Effects of aging and exercise on insulin action in rat adipocytes are correlated with changes in fat cell volume.

The effects of exercise on insulin action were evaluated in epididymal adipocytes from 9-mo and 26-mo-old rats. Exercised animals were given voluntary access to running wheels at 6 mo of age. Comparisons were made among these animals, freely eating sedentary rats, and sedentary animals maintained at body weights comparable to those of the runners. When expressed as percentage changes, the responses to insulin, in terms of stimulation of both [U-14C]glucose oxidation and 14C-labeled lipid accumulation, were largest in fat cells from the runners, followed by the paired-weight adipocytes, and the cells from the freely eating sedentary animals. However, the absolute changes in the rates of glucose oxidation and 14C-labeled lipid synthesis produced by insulin were comparable among the different groups. Basal rates of oxidation and 14C-labeled lipid accumulation were directly correlated with average cell size, independent of the treatment group, whereas the percentage increases in these processes produced by insulin were inversely correlated with cell size. Little, if any, effect of age or exercise was observed that could not be attributed to the average fat cell volume.

Adipose Tissue↗
PubMed1981

Effective management of penetrating eye injuries in remote Australia.

In the transportation of patients with penetrating eye injuries, vomiting, hypoxia and infection are the main causes of serious ocular complications, and efforts must be directed at minimizing their occurrence. As long as definitive microsurgical repair is undertaken within 24 hours of injury, an optimal surgical result can be expected. In this paper full directions are given for the patient's immediate treatment. Accent is placed on careful and considered transportation.

Aircraft↗
PubMed1979

Eye protection.

Explore the source record for details and available documents.

Adult↗
PubMed1978

Eye injuries and the dentist.

The risk of damage to the eyes of the patient, the dentist and his assistant should be recognized. Protection can be achieved by the wearing of specially designed spectacles using CR 39 plastic tinted lenses. Contact lenses should be removed by patients who are to undergo general anaesthesia.

Athletic Injuries↗