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Biomedical subjects

K Leslie

Publications and source records attributed to K Leslie.

At least 19 recordsLinked to original sources
PubMed1996

Bone mass and soft tissue composition in adolescents with anorexia nervosa.

The relationship between bone mass and compartments of soft tissue was studied in 22 adolescent women with anorexia nervosa (mean, 17 years). Results were compared to data on age- and gender-matched controls. Bone mass of the lumbar vertebrae and femoral neck, fat and lean tissue was measured by dual energy X-ray absorptiometry (DXA). Bone mass in the central third of the skeleton, by neutron activation analysis (NAA), and body protein, by prompt gamma ray analysis (PGA), was measured on patients, but not controls. The patients had significantly lower values than controls in total weight (26%), lean tissue (16%), fat (60%), bone mass of lumbar spine (14%), and femoral neck (15%). The mean calcium bone index (CaBI), the central skeletal calcium normalized for body size based on height, was significantly lower than the value for external controls, (0.86 +/- 0.10 vs. 0.97 +/- 0.10). The nitrogen index (NI), body protein normalized for height, showed a similar reduction from external controls (0.84 +/- 0.10 vs. 1.0 +/- 0.10). Bone mass (both DXA and NAA data) was strongly correlated to lean tissue and to protein; the correlations to fat were weaker. Follow-up studies after 7-26 months in 12 patients showed a modest increase in weight (mean, 4.9 kg) which was due, primarily, to an increase in fat with only insignificant increase in lean tissue and in protein. In bone mass, there was either no change or further loss. Only four restored body weight to normal (BMI > 20) and they achieved normal menstruation, but even these four responders showed no increase in bone mass. Our studies confirm that adolescent females with anorexia nervosa suffer losses not only in all compartments of body composition, but also demonstrate that the restoration of bone mass lags behind improvement in soft tissue compartments. These results were independent of methods used for the measurements.

Absorptiometry, Photon↗
PubMed1996

Prediction of movement during propofol/nitrous oxide anesthesia. Performance of concentration, electroencephalographic, pupillary, and hemodynamic indicators.

BACKGROUND: Movement in response to painful stimulation is the end point classically used to assess the potency of anesthetic agents. In this study, the ability of modeled propofol effect-site concentration to predict movement in volunteers during propofol/nitrous oxide anesthesia was tested, then it was compared with the predictive abilities of the Bispectral Index and 95% spectral edge frequency of the electroencephalogram, pupillary reflex amplitude, and systolic arterial blood pressure. In addition, the relationships between simple end points of loss and recovery of consciousness, and pupillary, hemodynamic, and propofol concentration indicators were studied. METHODS: Ten healthy volunteers were anesthetized with an infusion of propofol, which was increased in three equal steps to 21 mg.kg lean body mass-1.h-1. After loss of the ability to hold a syringe and of the eyelash reflex, 60% nitrous oxide was introduced and the trachea was intubated without the use of muscle relaxants. The propofol infusion rate then was decreased to 15.4 mg.kg lean body mass-1.h-1. Ten minutes later, tetanic electrical stimulation was administered to the thigh via needle electrodes: if movement was observed within 1 min, the propofol infusion rate was increased by 1.75 mg.kg lean body mass-1.h-1 5 min after the stimulus; if not, it was similarly decreased. This 15-min sequence was repeated until volunteers "crossed over" from movement to no movement (or vice versa) four times. The propofol infusion rate then was increased to 21 mg.kg lean body mass-1.h-1, nitrous oxide was discontinued, the trachea was extubated, and the infusion rate was decreased in five equal steps over 50 min. The times at which the eyelash reflex returned and the birth date was recalled were recorded. The electroencephalogram was monitored continuously (FP1, FP2, ref: nasion, ground: mastoid). Measurements of the pupillary response, arterial blood pressure, and heart rate were recorded during induction and awakening, just before and for 5 min after each stimulation. Arterial blood samples were obtained for propofol assay, and propofol effect-site concentrations were calculated at each time. The predictive value of indicators was compared using a new static, the prediction probability (PK). RESULTS: Loss and return of the eyelash reflex occurred at greater propofol effect-site concentrations than either dropping the syringe or recall of the birthday. The propofol effect-site concentration (in the presence of 60% nitrous oxide) predicted to prevent movement after a supramaximal stimulus in 50% of volunteers was 1.80 micrograms/ml (95% confidence limits: 1.40-2.34 micrograms/ml). The Bispectral Index (PK = 0.86), 95% spectral edge frequency (PK = 0.81), pupillary reflex amplitude (PK = 0.74), and systolic arterial blood pressure (PK = 0.78) did not differ significantly from modeled propofol effect-site concentration (PK = 0.76) in their ability to predict movement. CONCLUSIONS: Indicators of pharmacodynamic effect, such as the electroencephalogram, pupillary light reflex, and systolic arterial blood pressure, predict movement as well as effect-site concentration during propofol/nitrous oxide anesthesia. Loss and return of the eyelash reflex correspond to a deeper level of anesthesia than syringe-dropping or recall of the birth date.

Adult↗
PubMed1996

Reduction in the shivering threshold is proportional to spinal block height.

BACKGROUND: Hypothermia is nearly as common, and may be as severe, during spinal and epidural anesthesia as during general anesthesia. The authors have proposed that thermoregulatory failure results when regional anesthesia increases apparent leg skin temperature to a level far exceeding actual leg skin temperature. Extensive dermatomal blocks will alter thermal input to the hypothalamus from a greater skin-surface area more than less extensive ones and thus might be expected to impair central thermoregulatory control more. Accordingly, they tested the hypothesis that reduction in the shivering threshold is directly related to the number of dermatomes blocked during spinal anesthesia. METHODS: Eleven men, aged 62 +/- 6 yr (mean +/- SD), undergoing urologic surgery were studied. Ice-cold lactated Ringer's solution was administered intravenously before spinal blockade and the shivering threshold (triggering core temperature) was established. Spinal anesthesia then was induced using a randomly assigned dose of 0.5% bupivacaine (2-4 ml). Again, sufficient cold lactated Ringer's solution was given to induce shivering. Tympanic membrane, ambient and skin temperatures were measured, and extent of block was defined by loss of temperature discrimination. Presence of shivering was evaluated by a blinded observer. Mean upper-body skin and ambient temperatures, cooling rates and intravenous fluid volumes at the two thresholds were compared using paired, two-tailed t tests (P < 0.05). Linear regression defined the relationship between reduction in shivering threshold and the number of dermatomes blocked. RESULTS: There were no significant differences between mean upper-body skin and ambient temperatures, cooling rates or intravenous fluid volumes at the control and spinal shivering thresholds. Spinal anesthesia reduced the shivering threshold in direct relation to the number of dermatomes blocked: delta threshold = 0.74 - 0.06 (dermatomes blocked); r2 = 0.58, P < 0.006. CONCLUSIONS: Extensive spinal blockade impairs central thermoregulatory control more than less extensive blockade. Clinicians can thus anticipate more core hypothermia during extensive than during restricted spinal blockade.

Aged↗
PubMed1996

Axillary brachial plexus block in two hundred consecutive patients.

Two hundred consecutive, minimally-sedated patients presenting for upper limb surgery were audited prospectively to determine the overall clinical success rate, extent of cutaneous neural blockade, reliability and complication rate of each indicator of axillary sheath entry, and degree of patient satisfaction. The axillary sheath was identified, using a 22 gauge, short-bevelled needle, by one of four indicators, whichever was elicited first (paraesthesia, arterial or venous puncture, or tethering by the axillary sheath). Alkalinized mepivacaine 1.2%, 50 ml then was injected. The cutaneous distribution of the block was mapped in the presence of minimal sedation. Anaesthesia was supplemented with peripheral nerve blocks where necessary. Patients were followed up with a mailed questionnaire and surgeon interview. The overall clinical success rate was 92.5%, improving to 99% with supplementary nerve blocks. Complete anaesthesia distal to the elbow was achieved in 85% of patients. Complications were common, but generally mild and transient: mild acute local anaesthetic toxicity, 3.5%; axillary tenderness and bruising, 12%; and dysaesthesias, 12.5%. Despite this, patient satisfaction was high (97%).

Adolescent↗
PubMed1995

Mild hypothermia alters propofol pharmacokinetics and increases the duration of action of atracurium.

Mild intraoperative hypothermia is common. We therefore studied the effects of mild hypothermia on propofol pharmacokinetics, hepatic blood flow, and atracurium duration of action in healthy volunteers. Six young volunteers were studied on two randomly assigned days, at either 34 degrees C or 37 degrees C. Anesthesia was induced with thiopental, 3 mg/kg, and maintained with 70% N2O and 0.6% isoflurane. Core hypothermia was induced by conductive and convective cooling. On the other study day, normothermia was maintained by a Bair Hugger (Augustine Medical, Inc., Eden Prairie, MN) forced-air warmer. Propofol, 1 mg/kg lean body mass (LBM), then was given, followed by a 4-h infusion at 5 mg.kg-1.h-1. After 2 h, atracurium 0.5 mg/kg was administered as an intravenous bolus. Indocyanine green was administered for estimation of hepatic blood flow. Arterial blood was assayed for propofol and indocyanine green concentration. Pharmacokinetic analysis was performed using NONMEM. Results are reported as means +/- SEM. Propofol blood concentrations averaged approximately 28% more at 34 degrees C than at 37 degrees C (P < 0.05). Hepatic blood flow decreased 23% +/- 11% in normothermic volunteers during the propofol infusion, and 33% +/- 11% in hypothermic volunteers (P = not significant). A three-compartment mamillary model fitted the data best. Inclusion of hepatic blood flow change from the prepropofol baseline as a covariate for total body clearance significantly improved the fit. The intercompartmental clearances were decreased in the presence of hypothermia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Propofol blood concentration and the Bispectral Index predict suppression of learning during propofol/epidural anesthesia in volunteers.

Propofol is often used for sedation during regional anesthesia. We tested the hypothesis that propofol blood concentration, the Bispectral Index and the 95% spectral edge frequency predict suppression of learning during propofol/epidural anesthesia in volunteers. In addition, we tested the hypothesis that the Bispectral Index is linearly related to propofol blood concentration. Fourteen healthy, male volunteers were studied on three randomly ordered days: no propofol, target propofol blood concentration 1 microgram/mL, and target propofol blood concentration 2 micrograms/mL. Each day, epidural anesthesia (approximately T11 level) was induced using 2% 2-chloroprocaine. Propofol was infused by a computer-controlled pump, and propofol concentration measured in central venous blood. We administered a Trivial Pursuit-type question task on all 3 days. The electroencephalogram was monitored continuously (Fp1, Fp2; reference, Cz; ground, mastoid). Propofol caused concentration-related impairment of learning. The propofol blood concentration suppressing learning by 50% was 0.66 +/- 0.1 microgram/mL. The Bispectral Index value when learning was suppressed by 50% was 91 +/- 1. In contrast, the 95% spectral edge frequency did not correlate well with learning. The Bispectral Index decreased linearly as propofol blood concentration increased (Bispectral Index = -7.4.[propofol] + 90; r2 = 0.47, n = 278). There was no significant correlation between the 95% spectral edge frequency and propofol concentration. In order to suppress learning, propofol blood concentrations reported to produce amnesia may be targeted. Alternatively, the Bispectral Index may be used to predict anesthetic effect during propofol sedation.

Adult↗
PubMed1994

Costs of elective total hip arthroplasty during the first year. Cemented versus noncemented.

The cost-effectiveness of the Mallory Head (Biomet, Warsaw, IN) cemented versus noncemented total hip arthroplasty was determined as part of a randomized trial. Costs were assessed during the first postoperative year. In-hospital resource use was determined using a chart review of 60 randomly selected patients. Costs were determined using a fully allocated costing model. Outpatient resource use was determined using patient diaries, and appropriate costs were allocated for outpatient visits, admissions to hospital, and patient-borne costs. There was no difference in costs between the cemented and noncemented prostheses. The average cost of the initial hospitalization was $9,990 (1988 Canadian dollars), and outpatient costs during the first year were $1,137 (total cost during the first year was $11,127). The cost per quality adjusted life year was $27,139 during the first year and $8,031 during the first 3 years.

Ambulatory Care↗
PubMed1994

Hypercarotenemia and transaminitis in female adolescents with eating disorders: a prospective, controlled study.

PURPOSE: Hypercarotenemia and transaminitis are reported as laboratory features of anorexia nervosa. However, the specificity and sensitivity of an elevation in serum carotene and transaminase are not known. Therefore, a prospective study was undertaken to determine the clinical utility of these serum markers. METHODS: Serum carotene was measured in 46 female adolescents between 13 years and 18 years of age (21 anorexia nervosa, 17 bulimia nervosa, 8 unclassified eating disorders). Findings were compared to levels of carotene in serum samples obtained from similarly aged females with either chronic inflammatory bowel disease (22 Crohn disease, 11 ulcerative colitis) or acute medical symptoms not associated with undernutrition or intestinal inflammation (N = 26), and 21 children of either sex with dyspeptic symptoms. RESULTS: Serum carotene was elevated in 6/46 (13.0%) females with eating disorders compared with only 2/80 (2.5%) children in the three comparison groups (p < 0.01). Hypercarotenemia was present in 4/21 girls with anorexia nervosa compared with 0/17 females with bulimia nervosa (p = 0.11). Transaminitis was present in 38.5% (AST) and 7.7% (ALT) of eating disorder patients. Liver enzyme abnormalities, however, did not correlate with hypercarotenemia. Transaminitis was also not specific for eating disorders since transaminitis was observed with comparable frequency in the three comparison groups. CONCLUSIONS: These findings confirm that hypercarotenemia is a laboratory feature in some subjects with eating disorders, in particular, anorexia nervosa. The low sensitivity (13.0%) does not provide justification for its use as a screening test. However, in complicated diagnostic settings a serum carotene determination could prove useful because the specificity (97.5%), positive predictive value (75.0%), and negative predictive value (66.1%) of an elevated carotene were high. These data also show that elevated carotene levels are not associated with hepatic abnormalities. Although transaminitis is reported as a laboratory feature of eating disorders, the prevalence of such abnormalities in this study was not higher than in age-matched comparison groups.

Adolescent↗
PubMed1994

Influence of dose on suxamethonium-induced muscle damage.

We have examined postoperative muscle pain and early increases in serum concentrations of myoglobin after administration of suxamethonium to see if these changes were dependent on the dose of drug. Thirty ASA I and II adult patients undergoing day-case surgery received a standard anaesthetic technique, including one of three doses of suxamethonium: 0.5, 1.5 or 3.0 mg kg-1. The incidence of postoperative myalgia and the severity of fasciculations were greater after suxamethonium 1.5 mg kg-1 than after a dose of 0.5 or 3.0 mg kg-1. Serum concentrations of myoglobin increased in a dose-dependent manner. Intubating conditions were significantly better with suxamethonium 1.5 or 3.0 mg kg-1 than with 0.5 mg kg-1. Changes in serum concentrations of calcium and potassium were small and similar in the three groups. We conclude that a dose of 3.0 mg kg-1 of suxamethonium provided a better combination of intubating conditions and minimal postoperative myalgia than the two lower doses.

Adult↗
PubMed1994

Propofol causes a dose-dependent decrease in the thermoregulatory threshold for vasoconstriction but has little effect on sweating.

BACKGROUND: Volatile anesthetics increase the core temperature required to trigger sweating and decrease the core temperature required to trigger vasoconstriction. However, little is known about the effects of intravenous anesthetics on thermoregulation. We therefore tested the hypothesis that propofol increases the sweating threshold and decreases the vasoconstriction threshold, thereby increasing the inter-threshold range (core temperatures not triggering autonomic thermoregulatory responses). The study was conducted using a new model in which thermal manipulations were restricted to insensate skin, and sensate skin temperature was controlled. METHODS: Six healthy, male volunteers were studied on 3 randomly ordered days: no propofol, target propofol blood concentration 2 micrograms/ml, and target blood propofol concentration 4 micrograms/ml. Each day, epidural anesthesia (approximately T11 level) was induced, using 2% 2-chloroprocaine (one volunteer received bupivacaine). Thermal manipulations were confined to the legs, and we attempted to maintain upper-body (sensate) skin temperature constant. Propofol was infused by a computer-controlled infusion pump. Volunteers were heated until sweating was observed, then cooled until fingertip vasoconstriction was observed. The sweating threshold was defined as the tympanic membrane temperature triggering sustained evaporative heat loss > 40 g.m-2.h-1. Similarly, the vasoconstriction threshold was defined as the tympanic membrane temperature triggering a sustained reduction in fingertip blood flow to < 0.25 ml/min. Central venous blood was assayed for propofol blood concentration. RESULTS: Increasing propofol concentration produced a linear decrease the vasoconstriction threshold (slope = -0.53 +/- 0.34 degrees C.microgram-1.ml-1; R2 = 0.98 +/- 0.04 [mean +/- SD]), but had little effect on the sweating threshold. The inter-threshold range was 0.51 +/- 0.46 degrees C during epidural anesthesia alone, and increased significantly, by 0.49 +/- 0.31 degrees C.microgram-1.ml-1 during propofol administration. CONCLUSIONS: Like volatile anesthetics, propofol reduces the vasoconstriction threshold and increases the inter-threshold range. However, propofol differs in leaving the sweating threshold unchanged.

Adult↗
PubMed1994

Attitudes of surgical residents toward trauma care: a Canadian-based study.

Surgical residents (n = 330) registered in training programs in the province of Ontario, Canada were surveyed about their attitudes toward trauma care related issues. Questionnaires were returned by 48%. Overall, 84% felt that their clinical exposure to trauma was adequate; 78% noted that the emphasis placed on trauma topics in their educational programs was appropriate; 50% spend > 10% of their current clinical time in trauma care. Orthopedic residents (n = 43) were different; 79% devoted > 10% and 29% > or = 30% of their time to trauma. Future clinical activity in trauma as practicing surgeons was expressed by 83% of the trainees: 31% intended < 10%, 46% 10%-30%, and 6% > 30% of their future practices to be related to trauma. The major positive factors of trauma were the scope and excitement of trauma care. The major negative factors were the night/weekend activity and the time away from family. We are encouraged by the results of this survey in that a significant number of residents perceive trauma as a clinical endeavor to be incorporated into their future surgical practices.

Adult↗
PubMed1994

A double-blind study of 250 cases comparing cemented with cementless total hip arthroplasty. Cost-effectiveness and its impact on health-related quality of life.

The success of a total hip arthroplasty (THA) is dependent on many more parameters than simply the prosthesis used. This study has demonstrated that a randomized controlled clinical trial of 250 patients comparing two types of hip prostheses (cemented versus cementless) with virtually complete follow-up examination is feasible. It also demonstrates that patients are willing to answer extensive quality-of-life questionnaires that allow complete assessment of the impact of hip arthroplasty on the patient's overall health-related quality of life. This study has also demonstrated that THA is an extremely effective intervention when one assesses its ability to impact on patients health-related quality of life with no difference between cement versus cementless at two years' follow-up examination.

Activities of Daily Living↗
PubMed1993

Helicobacter pylori infection in adolescents with eating disorders and dyspeptic symptoms.

The potential role of Helicobacter pylori infection of the antrum as a cause of symptoms of dyspepsia in patients with eating disorders was evaluated with an assay to detect H. pylori-specific IgG in serum. H. pylori-specific optical-density readings were comparable for adolescents with eating disorders (0.133 +/- 0.063, mean +/- SD) and for two comparison groups, and were lower than readings for children with documented H. pylori infection. Symptoms referable to the gastrointestinal tract did not correlate with H. pylori status in the teenagers with eating disorders.

Adolescent↗
PubMed1993

The effect of elective total hip replacement on health-related quality of life.

The effect of total hip replacement on the health-related quality of life of patients who have osteoarthrosis was examined as part of a randomized, controlled trial comparing femoral head prostheses that were inserted with or without cement. One hundred and eighty-eight patients were followed for three months: 179 of them, for six months; 156, for one year; and ninety, for two years. The health-related quality of life was assessed with use of the Harris hip score, the Merle d'Aubigné hip score, the Sickness Impact Profile, the Western Ontario and McMaster University (WOMAC) Osteoarthritis Index, the McMaster--Toronto Arthritis (MACTAR) Patient Preference Disability Questionnaire, and the time trade-off technique as a measure of utility. Patients also took the six-minute-walk test. The mean age of the patients in the study was sixty-four years (range, forty to seventy-five years); ninety-seven patients (53 per cent) were men and ninety-four (50 per cent) had a prosthesis inserted with cement. Only three of 188 patients refused to return for quality-of-life assessments. There was significant improvement in all health-related quality-of-life measures and in the six-minute-walk test after the operation (p < 0.01 for all items, except for the work dimension of the Sickness Impact Profile at three months [p = 0.07]). Most of the improvement had occurred by three months postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗