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Biomedical subjects

K Leslie

Publications and source records attributed to K Leslie.

At least 19 recordsLinked to original sources
PubMed2006

Effect of eprinomectin pour-on treatment around calving on reproduction parameters in adult dairy cows with limited outdoor exposure.

The objective of this study was to investigate if treatment of cows with eprinomectin around calving had any beneficial effects on the calving to first artificial insemination interval, calving to conception interval, and number of services per conception in totally- and semi-confined dairy herds. In totally-confined herds lactating- and dry-cows were housed throughout the summer and had no access to pasture. In semi-confined herds lactating- and dry-cows had limited outdoor exposure to a small pasture or paddock but were still fed a ration that met all their nutritional requirements. The study was carried out between February 2002 and February 2003 in 35 herds (2381 cows) located in Quebec, Ontario and Minnesota (USA) participating in a larger clinical trial. The herds kept electronic reproduction records. Cows were randomly allocated to receive eprinomectin or a placebo, with treatment being administered on or close to the day of calving. Monthly bulk tank milk samples from each farm were tested with an indirect ELISA using a crude Ostertagia ostertagi antigen and these data were averaged over the study year. The optical density ratio (ODR) values were then dichotomized into high and low using a cut-point of 0.50. Treatment effects were analyzed using Cox proportional hazards survival models with herd frailty effects for calving to conception and calving to first service intervals. Aalen's linear hazards model was used to investigate time-varying effects in the Cox models. A random effects poisson regression model was used to model the number of services per conception. Other predictor variables tested in the models were lactation number, calving season, study site, peak milk production, ODR and the lactating- and dry-cow housing variables. Overall, there was no significant effect of treatment on the three indices of reproductive performance. The effect of season of calving depended on how much time had passed since calving. Presumably this effect reflected a seasonal effect at the time of breeding. Hazard of conception in younger cows was higher than in older cows. Early bred cows tended to have a higher number of inseminations per conception than those bred late. The results of the study suggested that eprinomectin treatment at calving was not beneficial to reproduction.

Animal Husbandry↗
PubMed2006

Venous air embolism and the sitting position: a case series.

Venous air embolism is a potentially serious complication of neurosurgery that occurs more commonly when the patient is in the sitting position. In this study, we aimed to quantify the incidence of venous air embolism during neurosurgical procedures performed with the patient in the sitting position in our institution. We performed a prospective audit of venous air embolism in 100 consecutive patients who underwent neurosurgical procedures in the sitting position, as evidenced by a decrease in end-tidal carbon dioxide partial pressure of 5 mmHg or more within 5 min. The incidence of venous air embolism was 9% (95% confidence interval: 3.3-14.7%). These patients did not have a significantly higher rate of hypotension or desaturation. Our results suggest that the sitting position can be safely used in neurosurgery.

Adult↗
PubMed2006

Effect-site targeted patient-controlled sedation with propofol: comparison with anaesthetist administration for colonoscopy.

Patient-controlled sedation (PCS) allows patients to match their sedation requirement to perceived discomfort. The significant delay in onset of sedation may be overcome with effect-site steered target controlled infusion, but previously only trials in volunteers have been carried out. We therefore conducted a randomised, double-blind controlled trial comparing effect-site steered propofol PCS with anaesthetist-administered propofol sedation in 40 patients presenting for colonoscopy. The initial effect-site target in the PCS group was 0.8 microg.ml(-1), increment was 0.1 microg.ml(-1) and lockout was 3 min. Patient and endoscopist satisfaction and operating conditions were similar between the two groups. PCS patients were sedated more slowly (13 [7.1] vs. 3 [1.1] min; p < 0.0001) and less deeply (minimum BIS value: 71 [16] vs. 58 [15]; p = 0.13) than anaesthetist-administered propofol sedation patients. More of the latter patients were hypotensive, but all patients had similar recollection of events during the procedure and similar quality of recovery.

Adolescent↗
PubMed2006

Effect of spinal flexion on the conus medullaris: a case series using magnetic resonance imaging.

Anatomy textbooks state that the conus medullaris moves cephalad when the vertebral column is flexed. This could confer protection against spinal cord damage during dural puncture, but has not been demonstrated in vivo. We therefore imaged the spine of 10 volunteers using magnetic resonance imaging to determine if such movement occurs with the spine in the neutral and flexed positions. The position of the conus medullaris in relation to the superior endplate of the L1 vertebra was determined. On spinal flexion, the conus medullaris moved cephalad in three subjects and caudad in three subjects, with no change in the remaining four. The median overall movement (95% CI [range]) was 0 mm (4 mm caudad to 1 mm cephalad [3 mm caudad to 1 mm cephalad]; p = 1.0). Whilst spinal flexion may facilitate needle insertion during dural puncture, it is unlikely to confer extra protection against spinal cord damage.

Adult↗
PubMed2006

Intravenous fluid to prevent hypotension in patients undergoing elective colonoscopy.

Colonoscopy may be associated with hypotension during sedation leading to postoperative morbidity. However, no treatment is proven to ameliorate intraoperative hypotension for this procedure. We therefore conducted a randomized trial to determine the effect of intravenous fluid infusion on the incidence of hypotension during sedation for colonoscopy. With institutional approval, 160 patients presenting for elective colonoscopy were randomized to 1.5 ml/kg or 15 ml/kg Hartmann's solution before colonoscopy. All observers were blind to group allocation. The incidence of hypotension during sedation (29% vs 25%; P=0.59) and postoperative morbidity (nausea, vomiting, headache, drowsiness and dizziness) (41% vs 39%; P= 0.75) did not differ between the two groups. Hypotensive patients were older, had a higher baseline systolic blood pressure, and were thirstier after fluid infusion than normotensive patients. This study does not support the use of 15 ml/kg Hartmann's solution to reduce the incidence of hypotension or postoperative morbidity in patients undergoing elective colonoscopy.

Colonoscopy↗
PubMed2005

Dreaming during anaesthesia in patients at high risk of awareness.

Dreaming during anaesthesia is commonly reported but remains poorly understood. In this study, adult surgical patients at high risk of awareness were randomly assigned to receive bispectral index (BIS)-guided anaesthesia or routine care, and were interviewed about dreaming three times postoperatively. Dreaming patients (n = 134) were compared with all other patients who were interviewed at least once (n = 2251). Intraoperative dreaming was reported by 4.2%, 3.9% and 3.4% of patients at 2-4 h, 24-36 h and 30 days after surgery, respectively. Fewer BIS-monitored patients reported intra-operative dreaming at 2-4 h than control patients (2.7% vs. 5.7%; p = 0.004). Reports of dreaming were similar in the two groups at 24-36 h and 30 days. Dreaming patients were younger (p = 0.001); healthier (p < 0.001) and more likely to be women (p < 0.001), and were less satisfied with anaesthetic care (p = 0.004) than other patients.

Adult↗
PubMed2005

Consenting to blood: what do patients remember?

We sought to characterize the consent process for transfusion and determine its impact on patients' knowledge and level of comfort with receiving blood. We identified all adult patients who had received blood transfusion at a tertiary care centre over 3 months. Patients who were discharged each received a survey that assessed their (1) recall of the consent process, (2) recall of information conveyed, (3) assessment of the discussion's understandability and (4) perceived knowledge of as well as comfort level with transfusion as a result of the discussion. Overall, 80% of respondents recalled discussing and signing an informed consent. Information was mostly conveyed by attending physicians (35%) and consent obtained in the patient's hospital room (38%) or the preadmission clinic (19%). Although the majority recalled the consent process, many did not recall the discussion of specific transfusion risks or alternatives to donor blood (88%). Although the majority felt the discussion was at least somewhat understandable (77%), only 35% felt better informed and more comfortable with accepting blood. Despite implementation of written informed consent for transfusion, patients' recollection and understanding of risks and alternatives remain poor. This suggests the need for improving risk communication.

Adolescent↗
PubMed2005

Recovery from bispectral index-guided anaesthesia in a large randomized controlled trial of patients at high risk of awareness.

Electroencephalographic monitors of anaesthetic depth are reported to assist anaesthetists in reducing recovery times. We explored the effect of bispectral index (BIS) monitoring on recovery times in a double-blind, randomized controlled trial of 2,463 patients at high risk of awareness. Patients were randomized to BIS-guided anaesthesia or routine care. In the BIS group, anaesthesia was adjusted to maintain a BIS value of 40-60 from the commencement of laryngoscopy to the start of wound closure, and 55-70 during wound closure. In the routine care group, anaesthesia was adjusted according to traditional clinical signs. In multivariate models, BIS monitoring, female gender, lower American Society of Anesthesiologists' physical status and shorter duration of anaesthesia predicted faster time to eye-opening after anaesthesia, and faster time to post-anaesthesia care unit discharge. BIS monitoring did not affect times to tracheal extubation among patients admitted to the intensive care unit. We conclude that BIS monitoring has statistically significant, but clinically modest, effects on recovery times in high risk surgical patients.

Adult↗
PubMed2005

Effect of eprinomectin treatment at calving on milk production in dairy herds with limited outdoor exposure.

The objective of this study was to determine the effect of anthelmintic treatment at calving in herds that were totally or semiconfined during the summer. In totally confined herds, lactating and dry cows were housed throughout the summer and had no access to pasture. In semiconfined herds, lactating and dry cows had limited outdoor exposure to a small pasture or paddock but were still fed a ration that met all their nutritional requirements. The study was carried out between February 2002 and February 2003 in 65 herds enrolled with DHI and distributed in 4 regions in Canada and 1 state in the United States. Cows were randomly allocated to receive eprinomectin or a placebo, with treatment being administered on or close to day of calving. In May and June 2002, 8 fecal samples were collected from each farm and fecal egg counts (FEC) were determined. Monthly bulk tank milk samples from each farm were tested with an indirect ELISA using a crude Ostertagia ostertagi antigen. Monthly test-day milk production data were recorded for 200 d after calving. In general, FEC were very low (mean = 1 egg per gram, range = 0 to 27). Mean herd bulk milk ELISA optical density ratio (ODR) values for the whole year ranged between 0.22 and 0.80. The ODR values were dichotomized into high and low using a threshold of 0.5. Treatment effects were analyzed using a linear mixed model with herd and cow as random effects. The analysis was restricted to 4789 cows (23,956 test-day records) treated between 21 d before and 7 d after calving. Overall, there was no significant effect of treatment. However, there was a tendency for an interaction between treatment and ODR, as illustrated by a larger numerical difference in treated vs. untreated cows in high-ODR herds than in low-ODR herds. However, the confidence intervals for the treatment effects (kg/d of milk per cow) in high-ODR herds (-0.33 to 1.10) and in low-ODR herds (-0.53 to 0.14) were wide and included zero. Therefore, this study failed to show a beneficial effect of eprinomectin treatment in these totally or semiconfined herds.

Animal Husbandry↗
PubMed2004

Comparison of ligand-induced conformational changes and domain closure mechanisms, between prokaryotic and eukaryotic dehydroquinate synthases.

Dehydroquinate synthase (DHQS) is a potential target for the development of novel broad-spectrum antimicrobial drugs, active against both prokaryotes and lower eukaryotes. Structures have been reported for Aspergillus nidulans DHQS (AnDHQS) in complexes with a range of ligands. Analysis of these AnDHQS structures showed that a large-scale domain movement occurs during the normal catalytic cycle, with a complex series of structural elements propagating substrate binding-induced conformational changes away from the active site to distal locations. Compared to corresponding fungal enzymes, DHQS from bacterial species are both mono-functional and significantly smaller. We have therefore determined the structure of Staphylococcus aureus DHQS (SaDHQS) in five liganded states, allowing comparison of ligand-induced conformational changes and mechanisms of domain closure between fungal and bacterial enzymes. This comparative analysis shows that substrate binding initiates a large-scale domain closure in both species' DHQS and that the active site stereochemistry, of the catalytically competent closed-form enzyme thus produced, is also highly conserved. However, comparison of AnDHQS and SaDHQS open-form structures, and analysis of the putative dynamic processes by which the transition to the closed-form states are made, shows a far lower degree of similarity, indicating a significant structural divergence. As a result, both the nature of the propagation of conformational change and the mechanical systems involved in this propagation are quite different between the DHQSs from the two species.

Amino Acid Sequence↗
PubMed2004

Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial.

BACKGROUND: Awareness is an uncommon complication of anaesthesia, affecting 0.1-0.2% of all surgical patients. Bispectral index (BIS) monitoring measures the depth of anaesthesia and facilitates anaesthetic titration. In this trial we determined whether BIS-guided anaesthesia reduced the incidence of awareness during surgery in adults. METHODS: We did a prospective, randomised, double-blind, multicentre trial. Adult patients at high risk of awareness were randomly allocated to BIS-guided anaesthesia or routine care. Patients were assessed by a blinded observer for awareness at 2-6 h, 24-36 h, and 30 days after surgery. An independent committee, blinded to group identity, assessed every report of awareness. The primary outcome measure was confirmed awareness under anaesthesia at any time. FINDINGS: Of 2463 eligible and consenting patients, 1225 were assigned to the BIS group and 1238 to the routine care group. There were two reports of awareness in the BIS-guided group and 11 reports in the routine care group (p=0.022). BIS-guided anaesthesia reduced the risk of awareness by 82% (95% CI 17-98%). INTERPRETATION: BIS-guided anaesthesia reduces the risk of awareness in at-risk adult surgical patients undergoing relaxant general anaesthesia. With a cost of routine BIS monitoring at US16 dollars per use in Australia and a number needed to treat of 138, the cost of preventing one case of awareness in high-risk patients is about 2200 dollars.

Anesthesia Recovery Period↗
PubMed2004

Anaesthesia for endovascular treatment of cerebral aneurysms.

Endovascular treatment of cerebral aneuryms is now widely used and has important implications for the neuroanaesthetist. Significant issues include the decision to use general anaesthesia, factors associated with anaesthesia in the interventional radiology suite and treatment of complications. As endovascular treatment is now supported by evidence and established in practice, neuroanaesthetists should be involved in planning these procedures from a process, and individual patient, perspective.

Anesthesia↗
PubMed2004

Anaesthesia for neurosurgery in the sitting position.

The sitting position offers many advantages in terms of surgical access for posterior fossa and posterior cervical spine surgery. However, these advantages must be balanced against the risks which include venous and paradoxical arterial air embolism, cerebral and myocardial ischaemia secondary to hypotension, and complications of the positioning itself. These are largely in the domain of the neuroanaesthetist. In this paper, therefore, we will review the advantages, disadvantages and management of complications of the sitting position, from the neuroanaesthetist's perspective.

Anesthesia↗
PubMed2004

Effectiveness of bupropion as an aid to stopping smoking before elective surgery: a randomised controlled trial.

Smoking is a risk factor for complications during and after surgery, but most smokers are unable to quit before elective surgery. We tested the efficacy of bupropion in improving smoking cessation rates in this setting by enrolling 47 patients from the elective surgery waiting list in a double-blind randomised controlled trial. Patients receiving bupropion had a lower daily cigarette consumption at the time of hospital admission, median (IQR) cigarettes per day: 6 (2-7) vs. 15 (9-20), p = 0.046. They also had a reduction in end-expired carbon monoxide (p = 0.004), a known contaminant of cigarette smoke, and increased arterial oxygen saturation on pulse oximetry (p = 0.011). They were more likely to have stopped smoking at the 3-week visit (p = 0.036), but not at the 6-week visit (p = 0.25) or at the time of hospital admission for surgery (p > 0.99). This study found that smokers waiting for elective surgery are more likely to reduce or stop smoking when treated with bupropion.

Adult↗
PubMed2004

Molecular typing and distribution of Staphylococcus aureus isolates in Eastern Canadian dairy herds.

Macrorestriction analysis of SmaI-digested chromosomal DNA, using pulsed field gel electrophoresis (PFGE) was performed to type and estimate genetic relationships among 288 Staphylococcus aureus isolates recovered from 58 Eastern Canadian dairy herds. In addition, a subset of the collection was phage typed and evaluated for sensitivity to 10 antimicrobial compounds. Of 288 isolates recovered, 29 distinct PFGE types were identified. Based on estimates of genetic relationships, the PFGE types were assigned to six lineage groups, designated A through F. Of all of the isolates, ca. 93% were assigned to lineage groups A, D, or F. In 58.6% of herds, only a single PFGE type was recovered, while the remainder had two to four types. Of the 212 isolates evaluated for antimicrobial resistance, 24.5% were resistant to one or more antimicrobials. Resistance to penicillin (9.9%) was most common, followed by resistance to sulfadimethoxine (7.5%). Isolates resistant to multiple antibiotics were rare. A total of 63% of isolates responded to phages from groups 1 and 3, and 32.8% could not be typed with any of the phage strains used. The other 4.1% belonged to a variety of phage types. Most of the PFGE lineage group A and F isolates corresponded to phage groups 3 and 1, respectively, and most group D isolates were not typeable. PFGE typing had better discriminatory power than phage typing in defining the relatedness of the S. aureus isolates. Distribution of PFGE types and phage types was independent across regions and within herds.

Animals↗
PubMed2004

Intraoperative patient warming using radiant warming or forced-air warming during long operations.

Forced-air warming is the most commonly used and effective method of active warming. A new radiant warming device (Suntouch, Fisher and Paykel) may provide an alternative when the skin surface available for warming is limited. We conducted a randomized controlled trial to compare the efficacy of the Suntouch radiant warmer and forced-air warming. With ethics committee approval 60 surgical patients having procedures anticipated to be more than two hours in duration were recruited. Patients were randomized to either radiant warming or forced-air warming. All intravenous fluids were warmed but prewarming was not used. The final intraoperative core temperatures (degrees C) for the radiant warming and forced-air warming groups were 36.0 +/- 0.5 and 36.4 +/- 0.6 (P=0.002) respectively. No other patient variables were significantly different. The Suntouch is not as effective as the forced air warming for intraoperative warming during long surgical procedures. The device may be useful when forced-air warming is not possible.

Body Temperature↗
PubMed2004

Pethidine and skin warming to prevent shivering during endovascular cooling.

We tested the efficacy of pethidine and cutaneous warming to prevent shivering during percutaneous cooling in unanaesthetized patients. Ten patients scheduled for cranial neurosurgery received pethidine infusion and skin warming. The Setpoint internal heat-exchanging catheter was inserted and cooling to 33.5 degrees C was started. Clonidine and chlorpromazine were given as "rescue medication" to treat shivering. General anaesthesia was planned to be induced after cooling was complete. Rewarming was initiated at dural closure. Three patients successfully completed the protocol, cooling to 33.8 degrees C at a median rate of 3.6 (range: 3.4-3.8) degrees C/h. Two patients cooled to 33.8 degrees C but required treatment for shivering (cooling rate: 2.9 [2.8-3.1] degrees C/h). Four patients failed to cool adequately because of refractory shivering (cooling rate: 20 [1.5-2.9] degrees C/h). One patient did not shiver and yet failed to cool adequately (cooling rate: 0.76 degrees C/h). Rewarming was at a rate of 26 (1.2-4.3) degrees C/h. There were no significant complications arising from catheter placement. The combination of skin warming and pethidine was not reliable enough to be recommended for use during endovascular cooling in unanaesthetized patients.

Adult↗