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Biomedical subjects

J W Sleigh

Publications and source records attributed to J W Sleigh.

At least 19 recordsLinked to original sources
PubMed1999

The bispectral index: a measure of depth of sleep?

UNLABELLED: How does physiological sleep affect the Bispectral Index (BIS)? We collected electroencephalographic (EEG) data from five subjects during the early part of the night, comparing the changes in the BIS with the conventional EEG stages of sleep. We found that the BIS was a consistent marker of depth of sleep. Light sleep occurred at BIS values of 75-90, slow-wave sleep occurred at BIS values of 20-70, and rapid eye movement sleep occurred at BIS values of 75-92. The effects of natural sleep on the BIS seem to be similar to the effects of general anesthesia on the BIS. The BIS may have a role in monitoring depth of sleep. IMPLICATIONS: Electroencephalographic data were collected from five subjects during sleep. We found that the Bispectral Index decreased during increasing depth of sleep in a fashion very similar to the decrease in Bispectral Index that occurs during general anesthesia. This study further highlights the electroencephalographic similarities of states of sleep and general anesthesia.

Adolescent↗
PubMed1999

The use of polymerase chain reaction to detect septicemia in critically ill patients.

OBJECTIVE: To describe the use of bacterial DNA amplification of conserved bacterial 16S ribosomal DNA nucleotide sequences by polymerase chain reaction (PCR) to detect the presence of septicemia in critically ill septic patients. DESIGN: Case series of blood samples from septic patients comparing the PCR results with conventional blood culture results. SETTING: A general intensive care unit in a tertiary referral hospital. PATIENTS: Two sets of samples (n = 101 and n = 55) from patients diagnosed as clinically septic and requiring blood cultures. They were classified by internationally accepted criteria into systemic inflammatory response syndrome, severe sepsis, and septic shock groups. INTERVENTIONS: Blood samples taken in a sterile fashion concurrently for blood culture, and PCR of the bacterial 16S ribosomal RNA gene in leukocytes and plasma. Two different DNA extraction techniques for PCR were tried sequentially. MEASUREMENTS AND MAIN RESULTS: Blood culture and PCR positivity were measured in relation to the clinical classification of severity of sepsis. Using the initial extraction method (n = 101), ten patients were positive by both PCR and blood culture, eight patients were PCR positive and blood culture negative, and seven patients were blood culture positive and PCR negative. From the clinical criteria, PCR detected at least six true positives that had been missed on blood culture and missed four true Gram-positive bacteremias. When the initial code was broken, this deficiency was rectified using the improved extraction technique (n = 55), in which ten patients were positive by PCR and blood culture, 29 patients were PCR positive and blood culture negative, and two patients were PCR negative and PCR positive. CONCLUSIONS: We conclude that the use of PCR (for the 16S ribosomal DNA in the plasma) was significantly more sensitive than the use of conventional blood culturing techniques for the detection of bacteremia in seriously ill patients. This could prove to be a valuable adjunct to conventional blood cultures.

Adolescent↗
PubMed1998

Profile and cost of head injury patients admitted to the Waikato Hospital Intensive Care Unit.

AIMS: To examine the profile and hospital costs of head injury patients admitted to the Waikato Hospital Intensive Care Unit (ICU). METHODS: Data were collected on head injury patients admitted to ICU over 41 months and costs of head injury patients in ICU, the High Dependency Unit (HDU) and other wards were calculated. RESULTS: There were 286 head injury patients admitted to ICU, of whom 62% had a Glasgow Coma Score < or = 8. Times in the ICU and hospital were 1760 and 7352 days respectively. Costs per day were $2280 in ICU, $800 in HDU and $500 in other wards. The cost for ICU was $1,174,478 per year, and for the total hospital treatment, $2.05 million (83 head injury patients) per year. Admissions of head injury patients to all New Zealand ICUs were 777 over the year to June 1996. Thus, assuming similar costs to the Waikato Hospital, New Zealand hospitals spend each year approximately 10.9 million dollars on head injury patients in ICUs and 19 million dollars on overall hospital stays (including ICU). In a selected group of 123 severe head injury patients, the six month Glasgow Outcome Scores showed that 36% were in the moderate to severe disability categories and likely to cause major ongoing ACC costs. The costs of the 80% of head injury patients admitted to hospital but not admitted to ICU, and their prehospital and postdischarge costs were not studied. CONCLUSIONS: The New Zealand epidemic of head injuries continues to consume large amounts of the health money and produce major social costs.

Adolescent↗
PubMed1998

Physiological predictors of death in exsanguinating trauma patients undergoing conventional trauma surgery.

BACKGROUND: Severe truncal multi trauma patients often develop coagulopathy, acidosis and hypothermia that makes major reparative trauma surgery dangerous. It was aimed to try to develop physiological indicators that would predict a poor outcome when conventional reparative surgery was applied. These indicators may help in the decision to switch from conventional reparative surgery to surgery limited to the control of major haemorrhage or organ disruption: so-called 'damage-control' surgery. METHOD: A retrospective review was conducted of 40 patients with severe multivisceral trauma (Injury Severity Score (ISS) > 35) who were admitted to the intensive care unit at Waikato Hospital and who underwent conventional reparative surgery. RESULTS: Survival was strongly associated with base deficit (BD), core temperature and ISS. Using multiple logistic regression on these indices, outcome could be predicted with 92.5% accuracy (sensitivity = 93%, specificity = 92%, positive predictive value for death = 96%). Either severe hypothermia (< 33 degrees C) or severe acidosis (BD > 12 mEq/L), or a combination of moderate core temperature < 35.5 degrees C, and a BD of > 5 mEq/L were strong predictors of death if conventional reparative surgery was practised. CONCLUSIONS: At the above mentioned levels of physiological compromise, patient survival after conventional trauma surgery can be predicted to be very unlikely. Damage-control measures would be worth attempting.

Acid-Base Imbalance↗
PubMed1998

Caregiver burden at 1 year following severe traumatic brain injury.

Sixty-nine primary caregivers of adults with a severe traumatic brain injury (TBI) were assessed at 1-year post-injury. Caregivers completed questionnaires on the physical, cognitive, emotional, behavioural, and social functioning of the person with TBI. Caregiver objective burden, psychosocial functioning, and subjective burden were also assessed. Clinically significant levels of anxiety and depression were evident in over a third of the caregivers. Similarly, a quarter of the caregivers reported poor social adjustment. There was no consistent relationship between the prevalence of various types of objective burden and the level of subjective distress that resulted from these changes. The person with TBI's emotional difficulties, in particular their anger, apathy, and dependency, caused the greatest distress for caregivers. With regard to the impact that caregiving had on their own lives, caregivers were most distressed by the loss of personal free time. Results from a regression analysis indicated that the person with TBI's physical impairment, number of behavioural problems, and social isolation were the strongest predictors of caregiver burden. The impact that caring for a person with severe TBI can have on the extended family unit is discussed.

Adolescent↗
PubMed1998

Caregiver burden at 6 months following severe traumatic brain injury.

Sixty-nine primary caregivers of people with a severe traumatic brain injury (TBI) were assessed at 6 months post injury. Caregivers completed questionnaires on the physical, cognitive, emotional, behavioural, and social functioning of the persons with the TBI. Caregiver psychosocial functioning and levels of subjective and objective burden were also assessed. Clinically significant levels of anxiety, depression, and impairment in social adjustment were evident in over a third of the caregivers. The frequency with which various changes in the person with the TBI and types of objective burden were reported had little relationship to the degree of distress caused by these changes. The person with TBI's social isolation and negative emotional behaviours caused the greatest degree of stress for caregivers. Caregivers were also most distressed by the impact that caregiving had on their personal health and free time. The results from a multiple regression analysis suggest that it is the presence of behavioural problems in the person with the TBI that has the most severe and pervasive impact on all aspects of caregiver functioning. It is suggested that these findings be taken into account when providing rehabilitation services to people with TBI and their families.

Adolescent↗
PubMed1998

Nurse-administered subcutaneous morphine is a satisfactory alternative to intravenous patient-controlled analgesia morphine after cardiac surgery.

UNLABELLED: There are no comparisons of i.v. patient controlled analgesia (i.v. PCA) versus nurse-administered subcutaneous (NA s.c.) morphine for acute postoperative pain. We undertook a prospective, randomized, controlled clinical trial of 80 cardiac surgical patients to compare i.v. PCA with NA s.c. morphine for postoperative pain control. Visual analog scale (VAS) pain scores at rest and with movement, daily verbal pain relief scores, and side effect profiles were not significantly different. Total morphine requirements in the two groups were not significantly different. A physiotherapist's evaluation of the effectiveness of analgesia for chest physiotherapy revealed no difference between the two groups. We conclude that NA s.c. morphine, administered as required (up to hourly), is a satisfactory alternative to i.v. PCA morphine after cardiac surgery. IMPLICATIONS: In a prospective, randomized study, we have shown that nurse-administered subcutaneous morphine is a satisfactory alternative to i.v. patient-controlled analgesia after cardiac surgery.

Aged↗
PubMed1998

Microbial contamination of three-way taps on arterial lines.

Arterial lines with three-way taps are used to measure blood pressure and aspirate blood, and are a potential source of catheter-related sepsis. Swabs were taken daily from 118 three-way taps on 98 arterial lines in a general intensive care unit. Infusion lines were changed weekly but arterial cannulae were not changed routinely. An overall contamination rate of 24.6% was found with the predominant organism being coagulase negative staphylococcus. The three-way taps became increasingly contaminated with time but this was shown to be unrelated to the manipulation rates. Blood culture organisms in those showing contamination of the three-way taps showed no relationship to the bacteria causing the contamination.

Arteries↗
PubMed1998

The effect of intraoperative ventilation strategies on perioperative atelectasis.

Several methods of ventilation have previously been shown to reduce intraoperative atelectasis and alveolar to arterial oxygen gradient (A-a DO2) in healthy patients. This study was designed to show firstly the relative intra-operative benefit and secondly if any method had an effect on atelectasis postoperatively. Using a factorial design we randomized 24 patients to each of the four ventilatory interventions (manual inflations, large tidal volumes, PEEP, and pressure control inverse ratio ventilation (IRV)). The A-a DO2 was used as the measure of atelectasis and data collected intra- and postoperatively for 24 hours. The mean pre-induction A-a DO2 was 80 mmHg. This study demonstrated that PEEP and IRV were most effective in reducing intraoperative A-a DO2 (P < 0.05 ANCOVA). Using more than one intervention did not improve the A-a DO2. No method had any effect on postoperative A-a DO2.

Aged↗
PubMed1997

A model of the electrocortical effects of general anaesthesia.

In an attempt to describe how reduction in synaptic efficiency by general anaesthetic agents results in loss of consciousness, we examined the behaviour of a two-dimensional (a lattice of 80 x 80 cellular elements) cellular automaton (CA) computer model as the connectivity between cellular elements was altered. The lattice was taken to represent cortical elements with variable connectivity to their neighbours. The summation of the active elements of the CA lattice was taken to represent a simulated "EEG" signal. If cellular automation elements had a high probability of connectivity, the simulated EEG showed high frequency predominance and low amplitudes, similar to the desynchronized pattern in an alert person. As connectivity was decreased, median frequency in the simulated EEG decreased and amplitude increased, similar to that in anaesthetized patients. As in our model, we believe it is possible that the human central nervous system in the conscious resting state exists above a critical threshold of synaptic efficiency; awareness is associated with an increase in synaptic efficiency and anaesthesia with a decrease that sharply reduces cortical information transfer.

Anesthetics, General↗
PubMed1997

Variability of R-R, P wave-to-R wave, and R wave-to-T wave intervals.

We analyzed the effect of changing posture from supine to standing on the variability of R-R, P-R, and R-T intervals in 10 healthy volunteers using power spectral analysis. An electrocardiogram and respiratory trace were recorded before and after posture change. Variability in the P-R and R-T intervals was much less than in the R-R interval and demonstrated a lower-frequency (LF)-to-high-frequency (HF) ratio. Changing from a supine to a standing position showed no change in indexes of vagal influence on the P-R and R-T variability, in contrast to the well-documented decrease in the indexes of vagal influence on the R-R variability (HF power decreased from 2.33 to 0.41 ms2, P = 0.003; amplitude of the respiration-to-heart rate impulse response decreased from 31.6 to 14.4 ms.ml-1.s-1, P = 0.03; and LF/HF increased from 1.96 to 5.22, P = 0.005). We concluded from this study that the effects of standing were an observed reduction in vagal influence on the heart rate variability of the R-R interval and maintenance of lung volume-related vagal modulation of the P-R and R-T intervals.

Adult↗
PubMed1997

Heart rate variability following cardiac surgery fails to predict short-term cardiovascular instability.

The heart rate variability of 40 patients has been examined by spectral analysis following cardiac surgery. The heart rate variability was measured upon patient arrival in ICU in both a resting supine position, and following passive straight-leg raising. After 12 hours in ICU, the patients were classified as having been cardiovascularly stable or unstable according to a specially devised inventory. Their heart rate variability data was then examined to seek any predictor of instability. Passive straight-leg raising induced a decrease in spectral power across all of the component frequency bands. The LF/HF ratio rose with passive straight-leg raising, but failed to reach significance. None of these changes were sustained. There was no significant difference in heart rate variability patterns between the stable and unstable groups, and so no predictor was identified. Initial clinical assessment was also studied, and it too provided no reliable prediction of short-term cardiovascular instability.

Adolescent↗