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Biomedical subjects

K Leslie

Publications and source records attributed to K Leslie.

At least 55 records · Page 3Linked to original sources
PubMed2001

Coagulation studies in preoperative neurosurgical patients.

Unselected preoperative coagulation testing is known to have low positive yield. However, no study has specifically evaluated neurosurgical patients. A retrospective study of 1211 patients having neurosurgery over a one-year period was therefore conducted. Preoperative test results (activated partial thromboplastin time [aPTT], prothrombin time [PT] and platelet count) and historical factors indicating a potential bleeding tendency were recorded. Abnormality was defined as a test result outside the normal range for our laboratory. Seventeen per cent of all test results were abnormal. However, if abnormality was redefined as a test result indicating potential bleeding tendency (low platelet count, prolonged aPTT and/or PT), only 7.2% of results were abnormal. Many patients had factors on history indicating a potential bleeding tendency, but only a prolonged aPTT, cranial surgery and the use of anti-hypertensive and anaesthetic drugs preoperatively predicted postoperative bleeding. Prolonged aPTT was predictable on history in most patients. We conclude that routine screening of all preoperative neurosurgical patients in our hospital is unnecessary.

Blood Coagulation↗
PubMed2001

Propofol anaesthesia via target controlled infusion or manually controlled infusion: effects on the bispectral index as a measure of anaesthetic depth.

Target controlled infusions (TCI) of propofol allow anaesthetists to target constant blood concentrations and respond promptly to signs of inappropriate anaesthetic depth. Studies comparing propofol TCI with manually controlled infusion (MCI) reported similar control of anaesthesia, but did not use an objective measure of anaesthetic depth. We therefore tested whether the Bispectral Index (BIS), an electroencephalographic (EEG) variable, is more stable during propofol TCI or MCI. Forty patients received midazolam and fentanyl before induction and were randomized to TCI or MCI. Target propofol concentrations in the TCI group were 3 to 8 microg/ml. The MCI group received propofol bolus (approximately 2 mg/kg) and infusion (3 to 10 mg/kg/h). Neuromuscular blockade was achieved with rocuronium. Following endotracheal intubation, nitrous oxide (66%) in oxygen was delivered and propofol infusion and fentanyl boluses were titrated against clinical signs. Blood pressure, heart rate and EEG were recorded, although the anaesthetist was blind to BIS values. The ideal BIS for general anaesthesia was defined as 50. Performance error, absolute performance error, wobble and divergence of BIS, and maximum changes in blood pressure and heart rate were compared using two-sample t-tests or rank-sum tests where appropriate. There was no difference in absolute performance errors during maintenance of anaesthesia with propofol TCI or MCI (23 +/- 11% vs 23 +/- 9%; P=0.97). The two groups did not differ significantly in performance error, wobble, divergence on haemodynamic changes. We conclude that TCI and MCI result in similar depth of anaesthesia and haemodynamic stability when titrated against traditional clinical signs.

Adolescent↗
PubMed2000

Metabolic aspects in the etiology of displaced abomasum.

Results of studies on metabolic variables that exist prior to the diagnosis of displaced abomasum (DA) indicate that subclinical ketosis is a risk factor for DA. Serum aspartate aminotransferase activity, serum and milk betahydroxybutyric acid concentrations, and milk fat-to-protein ratios were often elevated before the diagnosis of DA, and these variables may be used to predict DA. Prevention of subclinical ketosis may prevent DA.

Abomasum↗
PubMed2000

Evaluation of eight cow-side ketone tests in milk for detection of subclinical ketosis in dairy cows.

The objective of this study was to evaluate eight cowside ketone tests when used with milk for detection of subclinical ketosis. A total of 469 dairy cows in the first week of lactation were studied. Twelve percent of these cows had subclinical ketosis, defined as >1400 micromol of beta-hydroxybutyrate/L of blood serum. The Pink test liquid and the Ketolac test strip were highly sensitive for subclinical ketosis when used with milk. The Uriscan and Rapignost test strips were poorly sensitive; the Ketostix, Ketur-Test, and Medi-Test-Keton test strips and the Acetonreagenz test tablet were insensitive for subclinical ketosis when used with milk. Pink and Ketolac milk ketone tests are potentially useful tools for use in a routine monitoring program to detect subclinical ketosis in early postpartal dairy cows.

3-Hydroxybutyric Acid↗
PubMed2000

The effect of tilmicosin administered to ewes prior to lambing on incidence of clinical mastitis and subsequent lamb performance.

The effect of tilmicosin on the incidence of clinical mastitis and subsequent lamb performance was studied in 9 sheep flocks in Ontario. Ewes were treated randomly with either tilmicosin or placebo approximately one month prior to lambing. Outcome was assessed by comparing rates of clinical mastitis, palpable udder abnormalities, and preweaning (50-day) lamb weights between the 2 treatment groups, while controlling for other important variables. Lambs raised by multiparous ewes treated with tilmicosin were significantly heavier than lambs from placebo-treated multiparous ewes at 50 days. Lambs from tilmicosin-treated ewes were on average 0.52 kg heavier than lambs in the placebo group. There was no difference between treatment groups in the weight of lambs from first parity ewes. Tilmicosin treatment resulted in a 43% decrease in palpable udder abnormalities. Incidence of clinical mastitis did not differ between experimental groups. The administration of tilmicosin prelambing, at the time of routine clostridial disease vaccination, may be a beneficial and convenient way to reduce mastitis infection and improve the preweaning gain of lambs.

Animals↗
PubMed1999

Common peroneal nerve stimulation for neuromuscular monitoring: evaluation in awake volunteers and anesthetized patients.

UNLABELLED: The study was conducted in two parts. First, evoked responses to common peroneal nerve stimulation at four electrode positions were tested in 25 awake volunteers. The initial threshold stimulus current (ITS) (minimal current producing dorsiflexion or eversion of the ankle joint and great toe) and the supramaximal stimulus current (SMS) (the point at which further increases in current did not produce increases in twitch tension) were defined. SMS was not reliably achieved using electrodes at each side of the fibular head. However, an exploratory electrode accurately located the nerve and enabled SMS in all volunteers (SMS/ITS = 3.4). Second, 16 anesthetized, paralyzed patients were studied. The common peroneal and ulnar nerves were stimulated simultaneously. Evoked tension was recorded at the adductor pollicis using a force transducer and at the great toe by a blinded observer. Reversal was given when the train-of-four count at the great toe reached four. Onset times were longer, and median posttetanic counts were greater, at the great toe compared with the adductor pollicis. Time from reversal to train-of-four ratio = 0.7 at the adductor pollicis was 207+/-160 s. We conclude that neuromuscular monitoring at the common peroneal nerve was not equivalent to monitoring at the ulnar nerve. IMPLICATIONS: Accurate neuromuscular monitoring is important for patient safety. We studied the accuracy of monitoring at the common peroneal nerve in volunteers and patients. An exploratory electrode accurately located the common peroneal nerve. Monitoring at the common peroneal nerve was not equivalent to monitoring at the ulnar nerve in patients.

Adult↗
PubMed1999

Safety and efficacy of target controlled infusion (Diprifusor) vs manually controlled infusion of propofol for anaesthesia.

In this multi-centre, randomized trial, we compared the safety and efficacy of Diprifusor TCI with manually controlled infusion (MCI) of propofol for anaesthesia. With approval, 123 adult male and female patients were studied. Firstly, each investigator anaesthetized five patients to familiarize themselves with Diprifusor TCI. In Stage 2, 98 patients were randomized to receive propofol-based anaesthesia via TCI or MCI. Adjuvant drugs, airway management and monitoring were managed at the discretion of the anaesthetist. Results are presented as mean (SD). Induction times were significantly longer [67 (32) vs 54 (17)s] and induction doses were significantly lower [14 (5) vs 16 (4) ml] in the TCI vs the MCI group. Recovery times and total doses were not significantly different. There were statistically but not clinically significant differences in mean arterial blood pressure and heart rate. Quality of anaesthesia and ease of control of anaesthesia were similar. We conclude that Diprifusor TCI and MCI are similar in terms of safety and efficacy.

Anesthesia, General↗
PubMed1999

The association between first DHI milk-test parameters and subsequent displaced abomasum diagnosis in dairy cows.

First Dairy Herd Improvement Corporation (DHI) test milk that was sampled prior to displaced abomasum (DA) diagnosis was used to examine the association between milk yield (kg), fat (%), protein (%), or fat/protein ratio and DA in dairy cows. 27 DA cases were matched to 3 controls per case by herd and calving date. Logistic regression was used to examine the effect of each milk parameter on the odds of DA, adjusting for lactation number and days in milk (DIM) at test. Higher odds of DA diagnosis was found with lower milk yield, higher milk fat percentage, lower milk protein percentage and higher fat/protein ratio. We conclude that milk yield, fat percentage, protein percentage and fat/protein ratio may be used to detect cows at risk for DA. Our findings also indicate that cows diagnosed with DA were energy deficient prior to DA diagnosis.

Abomasum↗
PubMed1998

Epidural fentanyl reduces the shivering threshold during epidural lidocaine anesthesia.

UNLABELLED: Epidural local anesthetics and IV opioids both decrease the core temperature that triggers shivering. However, the effect of epidural opioids on shivering thresholds has not been assessed. In this study, we tested the hypothesis that adding epidural fentanyl to epidural lidocaine decreases the shivering threshold compared with epidural lidocaine alone. Fourteen healthy male patients undergoing extracorporeal shockwave lithotripsy under epidural anesthesia were randomly assigned to receive either epidural lidocaine or epidural lidocaine plus epidural fentanyl. Ice-cold lactated Ringer's solution was given IV before epidural blockade, and the core temperature that triggers shivering was established. Then epidural anesthesia was induced, and the shivering threshold was established again after lithotripsy. Results were analyzed using paired or unpaired t-tests. Reduction in the shivering threshold by epidural anesthesia was significantly greater when fentanyl was added to lidocaine than when lidocaine was used alone (mean +/- SD: -0.6+/-0.4 degrees C versus -0.1+/-0.4 degrees C; P < 0.02). We conclude that patients are at increased risk of hypothermia when fentanyl is added to epidural lidocaine. IMPLICATIONS: Fentanyl is often added to lidocaine to improve the quality of epidural blockade and to reduce side effects. However, this study shows that patients are at increased risk of hypothermia when fentanyl is added to lidocaine.

Adult↗
PubMed1998

The association between selected metabolic parameters and left abomasal displacement in dairy cows.

The objective of this study was to examine the association between selected metabolic parameters and subsequent left displaced abomasum (LDA) diagnosis in dairy cows. Forty-four LDA cows sampled in the third week ante partum (a.p.) which was at a median of 34 days prior to LDA diagnosis, 36 LDA cows sampled in the first week post partum (p.p.) which was at a median of 14 days prior and 28 LDA cows sampled in the second week p.p., which was at a median of 9 days prior to LDA diagnosis were used. Each case was matched to 3 controls by herd and calving date. Data were available from a large field study. Aspartate-aminotransferase (AST) activity, the concentrations of beta-hydroxybutyrate (BHB), glucose, calcium and urea in blood, and the body condition score (BCS) were studied. Logistic regression was used to analyse the association between these parameters and subsequent LDA, adjusting for the effects of parity and pretreatment. A separate model was used for each sampling week and each parameter. In the third week a.p. none of the parameters were significantly associated with LDA. AST and BHB sampled in the first week p.p. and in the second week p.p. were significantly associated with LDA diagnosis. The higher the AST and BHB, the higher the odds of being diagnosed subsequently with LDA. The lower glucose and Ca in the second week p.p. the higher the odds of subsequent LDA diagnosis. Urea and BCS were not significantly associated with LDA in any of the weeks examined. We conclude that AST and BHB in the first and second week p.p. might be used as tests for subsequent LDA. Glucose, calcium, urea and body condition were either not significantly associated with LDA or significantly associated only in the second week p.p.; this may limit their use as tests for LDA.

3-Hydroxybutyric Acid↗
PubMed1998

Analysis of survivorship after displaced abomasum is diagnosed in dairy cows.

The objective of this study was to analyze the survivorship of dairy cows after displaced abomasum was diagnosed. Survivorship from the calving preceeding diagnosis of displaced abomasum to removal from the herd was investigated for cows that were diagnosed with displaced abomasum compared with herdmates. For cows that were diagnosed with displaced abomasum, factors that affected survivorship from the diagnosis of the disease to removal were investigated. Data from a total of 135 cows that had been diagnosed with displaced abomasum and 373 controls matched by herd and lactation number were available from a database at the University of Guelph. The hazard rate of removal from the herd was estimated using proportional hazard regression adjusted for intraherd correlation. Diagnosis of displaced abomasum significantly increased the hazarad rate of removal from the herd. For cows that were diagnosed with displaced abomasum the hazard rate of removal increased as parity increased. However, the hazard rate decreased with recurrent displaced abomasum and with higher days in milk at diagnosis of the disease. Although the 305-d milk production of cows that were diagnosed with displaced abomasum was lower during the lactation when the disease was diagnosed, 305-d milk production was not associated with removal of cows with that disease from the herd. Milk production during subsequent lactations did not differ between cows that were diagnosed with displaced abomasum and control cows. Low milk production during the subsequent lactations increased the hazard of removal of cows with that disease from the herd.

Abomasum↗
PubMed1998

Evaluation of five cowside tests for use with milk to detect subclinical ketosis in dairy cows.

The objective of this study was to evaluate the characteristics of five ketone tests for use with milk to detect subclinical ketosis [defined as > 1200 mumol of beta-hydroxybutyrate (BHBA)/L of blood] in dairy cows. The tests studied were the Ketolac BHB strip to detect BHBA (Hoechst, Unterschleissheim, Germany) and four tests based on sodium nitroprusside to detect acetoacetate (Rothera tests) [Ketostix strip (Bayer, Etobicoke, ON, Canada), Bioketone powder (Societé d' Analyses Biopharmaceutiques, Laval, QC, Canada), Ketocheck powder (Great States, St. Joseph, MO), and Utrecht powder (University of Utrecht, Utrecht, The Netherlands)]. Milk samples (n = 529) from 266 cows in 25 Ontario dairy herds were used for this investigation. The Ketolac BHB strip at 50 and 100 mumol of BHBA/L of milk showed sensitivities of 92 and 72%, respectively. This test was more sensitive for subclinical ketosis than were any of the Rothera tests. The sensitivities of the Rothera tests were 43, 33, 28, and 5%, respectively, for Utrecht powder, Bioketone powder, Ketocheck powder, and Ketostix strip. The Rothera tests were highly specific, as was the Ketolac BHB strip at 200, 500, and 1000 mumol of BHBA/L of milk (specificity, > 97%). The prevalence of subclinical ketosis was highest during the first 6 wk of lactation, and a peak was detected during the 2nd wk of lactation. Of the tests evaluated in this study, Ketolac BHB strip was the most useful to monitor subclinical ketosis in dairy herds.

3-Hydroxybutyric Acid↗
PubMed1998

Extension of useful reagent shelf life beyond manufacturers' recommendations. Cell Markers Committee of the College of American Pathologists.

OBJECTIVE: The College of American Pathologists Cell Markers Committee designed a study to evaluate the use of immunohistochemistry primary antibodies beyond manufacturers' recommended dates. METHODS: Pathologists were asked to save aliquots of primary antibodies during mid-1997 so that by spring 1998 the reagents would be "outdated" according to manufacturers' recommendations. Three tumors were immunostained both in mid-1997 and early 1998 (using outdated reagents in 1998). Two hundred twenty-one laboratories participated. PATIENT SAMPLES: Immunostained materials consisted of an angiomyolipoma immunostained for muscle-specific actin and HMB-45, a melanoma immunostained for S100 protein and HMB-45, and a large cell lymphoma immunostained for common leukocyte antigen and HMB-45. Blocks from the same tumor were used in each instance. MAIN OUTCOME MEASURE: We compared the immunostaining results as a percentage of laboratories indicating a positive or negative immunohistochemical result between the 1997 and 1998 time points. RESULTS: Only minor differences were identified for the 221 reporting laboratories in 1998 as compared with those in 1997. CONCLUSIONS: The data suggest review of the Health Care Financing Administration's ruling on extending the useful reagent shelf life beyond manufacturers recommendations. Similar studies using more inherently quantitative methodology are suggested.

Antibodies↗
PubMed1998

The implications of hypothermia for early tracheal extubation following cardiac surgery.

Thermoregulation is impaired during anesthesia for cardiac surgery. Redistribution of body heat and heat loss to the environment result in mild hypothermia before cardiopulmonary bypass. Maintenance of normothermia, rather than hypothermia, may facilitate early tracheal extubation. Hypothermia alters the distribution and decreases the metabolism of most drugs, including anesthetic drugs and muscle relaxants, thus prolonging recovery. Postoperative shivering increases metabolic rate and potentially leads to myocardial ischemia; prevention is therefore critical to the success of early tracheal extubation after cardiac surgery. Coagulopathies, increased incidence of surgical wound infection, and perioperative cardiac morbidity are other potential risk factors identified in noncardiac patients. Hypothermia, however, does have potential benefits to the patient, including protection from cerebral ischemia and hypoxemia. Mild core hypothermia (approximately 34 degrees C) may represent the optimal balance between risks and benefits for fast-track patients.

Anesthesia Recovery Period↗
PubMed1997

The arterial blood propofol concentration preventing movement in 50% of healthy women after skin incision.

To target appropriate drug concentrations and to facilitate comparisons between drugs, the potency of propofol must be firmly established. We therefore determined the arterial blood propofol concentration preventing movement in 50% of patients after skin incision and the ability of arterial blood pressure and heart rate to predict movement after incision. Fifteen healthy women scheduled for breast surgery were randomly assigned to computer-targeted propofol blood concentrations. No other drugs were administered. Fifteen minutes after starting the propofol infusion, a 5-cm skin incision was made. Patients were observed for gross purposeful movement for 1 min. Arterial blood was sampled for propofol to confirm steady-state blood concentrations. Arterial blood pressure and heart rate were measured noninvasively. Logistic regression was used to calculate the propofol blood concentrations and arterial blood pressures at which 50% and 95% of patients did not move after skin incision (CP50 and CP95, MABP50 and MABP95, respectively). The CP50 and CP95 values for propofol were 14.3 +/- 1.6 microg/mL (mean +/- SE) and 20.6 microg/mL, respectively. The MABP50 and MABP95 values were 63 +/- 4 mm Hg and 43 mm Hg, respectively. Heart rate did not differ significantly in patients who moved and who did not move. Propofol blood concentrations required to prevent movement in most patients resulted in significant arterial hypotension.

Adult↗