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Biomedical subjects

K Millar

Publications and source records attributed to K Millar.

At least 19 recordsLinked to original sources
PubMed2006

The effects of brief sevoflurane-nitrous oxide anaesthesia upon children's postoperative cognition and behaviour.

This study assessed the effects of brief sevoflurane-nitrous oxide anaesthesia on children's postoperative cognition, behaviour and physical morbidity. Forty-eight children aged 5-10 years undergoing anaesthesia without premedication for multiple dental extractions, and 48 control children, performed tests of choice reaction time, attention, psychomotor co-ordination and memory pre-operatively (baseline), prior to discharge and at 48 h (anaesthesia group only). Physical and psychological morbidity were recorded at 1 week. Mean choice reaction time and psychomotor co-ordination were significantly impaired postoperatively but had recovered at 48 h. However, measures of performance variability suggested the presence of residual impairment. Profound retrograde amnesia affected postoperative and 48-h recall of pictorial stimuli presented prior to anaesthesia, but recognition memory was unimpaired. Attention-seeking, tantrums, crying and nightmares were occurring more frequently in some 8-20% of children 1 week after the procedure.

Ambulatory Surgical Procedures↗
PubMed2004

Patient maintained sedation for colonoscopy using a target controlled infusion of propofol.

In this study, we evaluated safety and recovery using a patient maintained, target controlled infusion of propofol for sedation in 20 patients undergoing colonoscopy. Using a handset with a two-minute lockout interval, patients could make 0.2 micro g.ml(-1) increments to an initial target plasma concentration of 1 micro g.ml(-1) up to a maximum 4.5 micro g.ml(-1). Four patients became oversedated but required no airway or circulatory interventions. Subjects had a significant reduction in mean (SD) heart rate: 78.7 (15) vs. 69.8 (13.5) (p < 0.001) and in systolic blood pressure 121.1 (13.2) mmHg vs. 96.5 (8.6) mmHg (p < 0.001). Choice reaction time testing 15 min after colonoscopy showed a significant median (IQR [range]) rise of 162 (- 16, 383.3 [-199-859]) ms (p < 0.05). Six patients had faster reaction times postcolonoscopy. All patients denied unpleasant recall and were satisfied with the system. Although oversedation was a problem in this model, we conclude that patient maintained propofol sedation could be possible for colonoscopy.

Adult↗
PubMed2004

A partially blinded randomised controlled trial of patient-maintained propofol sedation and operator controlled midazolam sedation in third molar extractions.

Patient-maintained sedation using propofol has recently been shown to be effective for dental surgery. We compared this new technique to the established technique of operator administered midazolam. The two groups were compared before, during and after sedation. The two primary outcomes were time until discharge and oxygen saturation. Vital signs, anxiety and psychomotor skills were also compared. State anxiety was reduced to a greater extent in the propofol group (mean difference 10 (SD 4) mm; p = 0.010. Propofol patients recovered quicker (mean difference 7 (SD 1.4) min; p = 0.001). Propofol patients had a smaller reduction in arterial oxygen saturation (mean difference 0.8 (SD 0.3)%; p = 0.030), and a reduced increase in heart rate (mean difference 9 (SD 2) beats.min(-1); p < 0.001). Both techniques were well tolerated and safe. Propofol sedation offered superior anxiolysis, quicker recovery, less amnesia and less depression of simple psychomotor function.

Adolescent↗
PubMed2003

Long term neuropsychological outcome after head injury: relation to APOE genotype.

BACKGROUND: Existing evidence suggests that some patients who sustain a head injury suffer cognitive decline many years later, and that head injury and possession of the APOE epsilon 4 allele are each risk factors for Alzheimer's disease. OBJECTIVE: To determine whether late cognitive decline after head injury is more prevalent among carriers of APOE epsilon 4. METHODS: A database of head injured patients was used. Initial assessment was at the time of their injury, between 1968 and 1985, and outcome data at six months were available. Their ages at the time of injury ranged between 2 and 70 years. A cohort of 396 subjects was reassessed at a mean of 18 years later, with determination of APOE genotype and detailed neuropsychological testing. RESULTS: Judging by the Glasgow outcome scale, twice as many patients had deteriorated as improved between six months after injury and the late assessment; 22.2% of APOE epsilon 4 carriers had a good late outcome compared with 30.5% of non-carriers (95% confidence interval for the difference, -0.7% to 17.2%; p = 0.084). There were no clear differences between epsilon 4 carriers and non-carriers in detailed neuropsychological assessments. CONCLUSIONS: Although this study provides additional evidence that a late decline may occur after head injury, there was no clear relation to APOE genotype. Despite the follow up interval of 15 to 25 years, the cohort is still too young (mean age 42.1 years) to assess the risk of Alzheimer's disease.

Adolescent↗
PubMed2002

Humic acid enhanced remediation of an emplaced diesel source in groundwater. 1. Laboratory-based pilot scale test.

The enhanced solubility of petroleum-derived compounds in humic acid solutions is the basis for a new groundwater remediation technology. In this unique pilot-scale test, a stationary contaminant source consisting of diesel fuel was placed below the water table in a model sand aquifer (1.2 x 5.5 x 1.8-m deep) and flushed with water at a flow rate of 2 cm/h over 5 years. At 51 days, laboratory grade humic acid was added to the water and maintained at a level of approximately 0.8 g/l. The addition of humic acid had only a small impact on the aqueous transport of the BTEX components, which were rapidly dissolved from the diesel, but had a large effect on the flushing of PAHs, including methylated naphthalenes (MNs). Binding to aqueous humic acid enhanced the solubilization of MNs two- to tenfold. During aqueous transport, biodegradation of the BTEX and PAHs occurred, limiting the lateral and longitudinal extent of the diesel contaminant plume in the model aquifer. It appears that through enhanced solubilization, the overall biodegradation rate of the MNs was increased. As the various MNs were depleted from the diesel source, the MN plume shrank and then disappeared.

Biodegradation, Environmental↗
PubMed2002

Randomized clinical trial of no wound drains and early discharge in the treatment of women with breast cancer.

BACKGROUND: Women undergoing surgery for primary breast cancer routinely have suction drains inserted deep to the wounds, which are removed approximately 6-8 days after operation, requiring a period of stay of that duration in hospital. The aim of this study was to perform a prospective randomized clinical trial to evaluate a new surgical technique of suturing flaps without wound drainage, combined with early discharge, in women undergoing surgery for breast cancer. METHODS: A total of 375 patients undergoing surgery for breast cancer were randomized to conventional surgery or suturing of flaps with no drain. The main outcome measures were length of hospital stay, surgical morbidity, psychological morbidity and health economics. RESULTS: Suturing of flaps and avoiding wound drainage in women undergoing surgery for breast cancer resulted in a significantly shorter hospital stay. Adopting this surgical technique with early discharge did not lead to any difference in surgical or psychological morbidity. Health economic benefits to the National Health Service resulted from saved bed days with no impact on community costs. CONCLUSION: Wound drainage following surgery for breast cancer can be avoided, thereby facilitating early discharge with no associated increase in surgical or psychological morbidity.

Bed Occupancy↗
PubMed2001

Pre-existing cognitive impairment as a factor influencing outcome after cardiac surgery.

Conventional methodology to investigate cognitive impairment after coronary artery bypass graft (CABG) surgery leaves unclear the potential for pre-existing cognitive deficits to influence outcome. Individuals with pre-existing deficits may be more vulnerable to the effects of CABG, hence biasing the results of a typical prospective trial if account is not taken of their state. The present study examined the effect of pre-existing cognitive impairment upon cognitive outcome in 81 patients undergoing CABG. Patients performed the Stroop Neuropsychological Screening Test and other psychometric assessments prior to and at 6 days and 6 months after CABG. Those with pre-existing cognitive deficits were significantly more likely to display impairment at 6-day and 6-month follow-ups than were those without pre-existing deficits. Greater age and lower pre-morbid intelligence were also significant predictors of post-CABG deficit, confirming earlier findings. The results imply both that pre-existing cognitive impairments may render patients more vulnerable to post-operative deficits and that, in the absence of such pre-existing impairments, CABG surgery does not inevitably lead to later deficits. The study also replicated previous findings showing a similar influence of pre-existing depression upon emotional state after CABG. Overall, the results confirm the importance both of a patient's pre-existing cognitive and emotional states, and the methodology to assess them, in influencing outcome after cardiac surgery and the conclusions to be drawn as to the supposed adverse effects of the procedure.

Adult↗
PubMed2001

Humic acids enhanced removal of aromatic hydrocarbons from contaminated aquifers: developing a sustainable technology.

Contamination by gasoline and diesel fuels is a threat to groundwater resources. Polynuclear aromatic hydrocarbons (PAHs) which can represent up to 60% of volume in diesel fuels are of particular concern because many of them are carcinogenic and they are persistent, especially in oxygen-limited environment. Despite the development of alternative approaches, pump and treat continues to be the leading technology for the remediation of groundwater contaminated by gasoline and diesel fuels. The efficiency of this technology is however limited by the low solubility of the aromatic hydrocarbons. The objective of this study was to investigate the influence of humic acids on the removal of aromatic hydrocarbons from petroleum products in groundwater aquifers and to evaluate the potential use of humic acids, as a cost effective additive, in groundwater and soil remediation. In order to prove the feasibility of using humic acid in the field, a pilot scale experiment was conducted in a model aquifer with a very dense monitoring network, providing controlled conditions only possible in a semi-artificial system. In addition, different sources of humic acids were compared with surfactants for their ability to bind PAHs.

Chromatography, High Pressure Liquid↗
PubMed2000

Blood propofol concentration and psychomotor effects on driving skills.

We studied psychomotor performance in 10 healthy volunteers during recovery after a target-controlled infusion of propofol. Choice reaction time, dual task tracking with secondary reaction time and a within-list recognition task were assessed at target blood propofol concentrations of 0.8, 0.4 and 0.2 microgram ml-1. Performance was impaired most at the highest blood propofol concentration (choice reaction time increased by a mean of 247 ms and secondary reaction time by a mean of 178 ms). Choice reaction time and dual task tracking with secondary reaction time were the most sensitive and reliable methods of assessment (significant difference from baseline (P < 0.05) at a propofol concentration of 0.2 microgram ml-1 with choice and secondary reaction time testing). Within-list recognition assessment of memory was not sufficiently sensitive at very low propofol concentrations. The impairment in choice and secondary reaction time with a blood propofol concentration of 0.2 microgram ml-1 was less than that observed with a blood alcohol concentration of 50 mg 100 ml-1 and no greater than that observed with a blood alcohol concentration of 20 mg 100 ml-1 in a previous study involving healthy volunteers.

Adult↗
PubMed2000

Blood alcohol concentration and psychomotor effects.

This study assessed the effect of intravenous alcohol infusions on psychomotor impairment and compared it with that of alcohol administered orally. Comparisons were made between three European drink-driving limits of blood alcohol concentration (BAC) (20, 50 and 80 mg 100 ml-1) and an oral dose of alcohol 0.75 mg kg-1. Twelve volunteers, aged 22-34 yr, were recruited. At targets of 20, 50 and and 80 mg 100 ml-1, the mean (SD) BAC was 22.1 (3.7), 51.5 (3.3) and 80.5 (4.2) mg 100 ml-1, respectively. The peak BAC following an oral dose of alcohol 0.75 mg kg-1 ranged from 19 to 68 mg 100 ml-1. In psychomotor testing, choice reaction time deteriorated with increasing BAC and showed significant differences between baseline and the 50 (P < 0.05) and 80 mg 100 ml-1 (P < 0.01) conditions. Dual-task secondary reaction time deteriorated with increasing BAC and showed a statistically significant difference between all groups and baseline (oral and 20 mg groups, P < 0.05; 50 and 80 mg groups, P < 0.01). Dual-task tracking in the 50 and 80 mg groups was significantly different from baseline (P < 0.05 and P < 0.01, respectively). Oral dosing resulted in widely variable BACs, making it difficult to assess psychomotor impairment reliably. An intravenous infusion enables the BAC to be maintained within a narrow range. This allows precision when investigating the effects of alcohol on psychomotor performance.

Administration, Oral↗
PubMed1999

Tissue plasminogen activator and its receptor in the human amnion, chorion, and decidua at preterm and term.

The plasminogen activator system consists of two proteins: tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA), which act upon their specific receptors to generate plasmin from plasminogen located on the cell surface. Plasmin then acts directly and indirectly to degrade the components of the extracellular matrix (ECM). This process is likely to be important in the normal turnover of the ECM of fetal membranes and in its premature weakening in preterm premature rupture of the fetal membranes. Quantitative Northern analysis and in situ hybridization have shown that the decidua expresses mRNA for tPA. However, the immunolocalized tPA protein was most strongly associated with the amnion and chorion, as was its receptor annexin II, suggesting that the amnion and chorion are the targets for decidual tPA. At term, decidual tPA expression was unaffected by labor, and the tPA receptor was elevated both before and after labor. At preterm, the converse was found: decidual tPA expression was significantly (p < 0. 05) up-regulated by labor, but the tPA receptor was not. The results suggest that the generation of plasmin at term would be controlled by an increased concentration of the tPA receptor in the amnion and chorion, whereas at preterm a pathological increase in plasmin would be generated by an overexpression of tPA, initiated by labor.

Amnion↗
PubMed1999

Is residual impairment after alcohol an effect of repeated performance?

BACKGROUND: The study examines the residual impairment of performance due to alcohol on the descending limb of the blood alcohol curve. The occurrence of residual impairment at low or zero levels of blood alcohol is well established but its cause is uncertain. It is hypothesized that residual impairment may be due in part to the methodological procedure of repeated performance testing in the post-ingestion period. METHODS: There were 80 volunteers randomly allocated to one of four treatment conditions: a) alcohol and repeated performance (A-R) where psychomotor tasks were performed at 20-min interval for 2 h post ingestion; b) alcohol and double performance (A-D) where tasks were performed only at 1 h and 2 h from ingestion; c) placebo and repeated performance (P-R); and d) placebo and double performance (P-D). Alcohol was administered as vodka to achieve a peak blood-alcohol concentration (BAC) of approximately 80 mg per 100 ml. Performance effects were assessed by a dual task of primary pursuit tracking and secondary visual reaction time, and a visual sustained attention task. RESULTS: Alcohol caused significant impairment of secondary reaction time, the effect being greatest at peak BAC. Sustained attention was also impaired by alcohol but the effect just missed significance. Repeated performance conditions were associated with significantly greater impairment of secondary reaction time and sustained attention when compared with double performance conditions. The factor of performance condition did not, however, interact with that of alcohol. CONCLUSIONS: The monotony and boredom that may be associated with repeated performance do not contribute to residual alcohol impairment.

Adolescent↗
PubMed1998

Effects of meal composition on blood alcohol level, psychomotor performance and subjective state after ingestion of alcohol.

Moderating effects of meal composition on psychomotor performance impairment and feelings after alcohol were examined in a between-subjects design. Fifty-one male volunteers fasted or received either a high carbohydrate (85% energy) or a high protein (94% energy) meal. Alcohol was administered at a dose to achieve a blood alcohol level (BAL) of 60 mg/100 ml, as a placebo. Subjects performed a dual task of primary tracking and secondary reaction time and a five-choice reaction time task. Feelings were also assessed by rating. The high carbohydrate meal reduced BAL at peak and 2 h after drinking, but a high protein meal had no significant effect. Although performance was impaired by alcohol, neither meal significantly reduced impairment and there was no effect of meal type on performance in the placebo condition. However, alcohol increased rated intoxication and the high carbohydrate meal reduced this effect. Subjects who had consumed high protein meals had more negative affect 2 h after alcohol than did subjects who had consumed high carbohydrate meals or fasted. It is concluded that there is only a weak relationship between BAL and performance impairment and food has only limited effects on impairment, although it reduces BAL.

Adolescent↗
PubMed1998

A system for psychomotor evaluation; design, implementation and practice effects in volunteers.

This paper describes the design, implementation and assessment of PsychE, psychomotor evaluation system. Six standard tests are included: numeric vigilance, a dual task, probed memory recall, simple reaction time, choice reaction time and semantic long-term memory. The test presentations are described in detail. Practice effects were assessed in 10 healthy volunteers and were only evident in the performance measures for the simple reaction time test. For the remaining five tests, stable performance was reached within a single test session. The volunteers were healthy and most were regular users of computers. Therefore, the lack of practice effects cannot be assumed for the general population. A control group is essential for all studies using these tests. The system is implemented on an IBM-compatible personal computer and includes a database shell for the convenient collection, storage and analysis of performance data.

Adolescent↗
PubMed1998

Category generation testing in the search for implicit memory during general anaesthesia.

We gave auditory examples of two semantic categories through headphones to 100 surgical patients anaesthetized with propofol and enflurane. This presentation was made during certain stages of the procedure, potentially associated with arousal, and during steady-state anaesthesia. Postoperative review using category generation tests showed successful priming in a pre-induction group but no evidence of implicit memory in the anaesthetized groups. These results suggest that timing an auditory input to coincide with surgical stimulation does not increase the probability of retrieval of information by this type of testing.

Acoustic Stimulation↗
PubMed1998

Processing messages about disease detection and health promotion behaviors: the effects of anxiety.

A study was conducted to examine the effects of anxiety on the processing of messages that encourage the performance of disease detection and health promotion behaviors. It was hypothesized that under high-anxiety conditions messages about health promotion behaviors would be processed more than messages about disease detection behaviors and that this effect would reverse under lower levels of anxiety. To test this hypothesis, the participants were required to read information designed either to increase or to decrease anxiety about health. Following the anxiety manipulation, participants received a strong or weak message promoting the performance of either health promotion or disease detection behaviors. Then participants were required to indicate their attitudes about the behavior, their cognitive responses to the message, and their recall of the message. The results support the hypothesis.

Journal Article↗
PubMed1997

Music in theatre: not so harmonious. A survey of attitudes to music played in the operating theatre.

Music played to staff in the operating theatre is thought to improve surgeons' concentration but its effects on other theatre staff are unknown. We surveyed 200 anaesthetists to determine the prevalence of music playing in the operating theatre and anaesthetists' attitudes to it. The response rate was 72% and of these 72% (104) worked in a theatre where music was played regularly. Around 26% of the sample felt that music reduced their vigilance and impaired their communication with other staff while 11.5% felt that music might distract their attention from alarms. Fifty-one per cent felt that music was distracting when a problem was encountered during the anaesthetic.

Adult↗