Biomedical subjects

L Susak

Publications and source records attributed to L Susak.

8 recordsLinked to original sources

PubMed1996

Midazolam following open heart surgery in children: haemodynamic effects of a loading dose.

Our objective was to establish the safety and effectiveness of a loading dose of midazolam for postoperative sedation of children recovering from open heart surgery; a prospective randomized placebo-controlled double-blind study was done with subjects randomized to three groups according to loading dose. I = 0.08 mg.kg-1; II = 0.04 mg.kg-1; and III = 0.00 mg.kg-1 (placebo). An open label continuous midazolam infusion protocol followed. Haemodynamic parameters were monitored. The study was discontinued following an adverse event involving the 23rd subject. When data for all 23 subjects were combined, there was a mean decrease of 10% in blood pressure (BP) 30 min after the loading dose (P < 0.001). Heart rate change was less significant. Clinicians identified four hypotensive episodes as temporally associated with the midazolam load, two each in Groups I (0.08 mg.kg-1) and III (placebo). One subject in Group I (the 23rd) became hypotensive within five min of receiving the loading dose, had a difficult clinical course and died four weeks postoperatively. We cannot conclude that the loading dose of midazolam had any systematic haemodynamic effect in our study population. Although the clinical course of the 23rd subject suggests a subset of more susceptible children (those who receive opioid analgesia with midazolam, are volume-restricted, and/or undergo more complex forms of surgical correction), many critical care patients are inherently physiologically unstable, and concluding clinically that blood pressure fluctuation is drug related may be erroneous.

Blood Pressure↗

PubMed1995

Long term stability of somatosensory evoked potentials and the effects of microgravity.

BACKGROUND: Exposure to microgravity causes a height increase of up to 70 mm that places traction on the spine and may possibly lead to spinal cord dysfunction. Somatosensory evoked potentials (SSEP) have been widely used to monitor spinal cord function. This study was carried out to determine the long-term stability of the latency of SSEP's in individual subjects and the feasibility of recording SSEP's in a microgravity environment. METHODS: Baseline values and variability of the latency of the cortical evoked potentials were established in seven subjects over periods of 1-2.5 years. These values were then compared with measurements made in six of the subjects during periods of microgravity on a KC-135 aircraft. The latency of the cortical potentials was also measured in the evening and in the morning before rising in a separate group of seven subjects, to determine whether there was any diurnal variation. RESULTS: The mean coefficient of variance of the latency of the SSEP was approximately 1.5% of the latency, and there were no changes in the latency over the period studied. There was no evidence of diurnal variation in the latency of the cortical SSEP. Satisfactory recordings of the SSEP were obtained in five of six subjects tested in microgravity. In three of these five subjects there was a significant decrease in the latency of the cortical SSEP in microgravity. CONCLUSIONS: In individual subjects the latency of the cortical SSEP varies within very small limits (1.5%) over 1-2.5 years. The results demonstrate the feasibility of recording SSEP's in the microgravity state. They show that relatively small changes (2-3 ms) in the latency of the SSEP can be detected when prior baseline values are established for each subject. The reason for the decrease in latency of the cortical SSEP in some subjects on the KC-135 is not known.

Adult↗

PubMed1994

The Vancouver sedative recovery scale for children: validation and reliability of scoring based on videotaped instruction.

We originally developed and tested the Vancouver Sedative Recovery Scale (VSRS) to measure recovery from sedation following paediatric open heart surgery and reported excellent clinical inter-observer reliability. We now report a new study using videotape instruction of novice raters and videotaped case examples to determine whether the instruction produces adequate skill with the VSRS. Inter-rater reliability was assessed using videotapes of 16 children across a range of ages (six months to six years), and all levels of sedation (unresponsive to fully awake). Variably randomized subsets of six of the 16 test cases were randomly assigned to be rated by each of 16 video-instructed ICU staff volunteers, according to a balanced incomplete block design, such that every pair of raters assessed two children in common. The validity of the ratings from the video-instructed raters was assessed by comparison with "gold standard" scores from two experts who rated all 16 children clinically as the test cases were videotaped. The experts were in agreement themselves (intraclass correlation of 0.976). The correlation between the novice scores (average of six ratings per video) and the live clinical scores (average of two expert ratings) was 0.977 over the 16 test cases. On average, the mean expert rating was slightly higher, but the difference was negligible. (The differences between the mean ratings of the experts and novices for 13 of the 16 videos are very close to zero, while the other three differences, from technically less good videos, are two standard deviations away from zero). The VSRS, video instruction method and incomplete block design may be of use to other clinicians and investigators.

Anesthesia Recovery Period↗

PubMed1992

Diurnal changes in the profile shape and range of motion of the back.

The diurnal height change reported to occur in young adults was investigated to characterize changes in the lumbar range of motion, spinal profile, and range of motion of the back. Twelve subjects aged 18-22 years were measured using stereophotography and standard clinical examinations in the evening and after a minimum of 8 hours of complete bed rest. The average increase in height was 20 mm. Forty percent of the height increase took place in the lumbar spine without change in the depth of the lordosis, and forty percent took place in the thoracic curve with a decrease in the kyphosis. The remaining 20% of the height increase was not located, but no measurements were taken of the cervical spine. Range of motion studies revealed that lumbar flexion, as measured using the lumbar flexion increment, was decreased in the morning, and straight leg raise was decreased when measured clinically but not when measured photographically. Extension, rotation, and femoral stretch test were not affected. The authors conclude that stereophotogrammetry offers an accurate, noninvasive way to study spinal profiles. Further work is needed to assess and quantify the relative motion of the skin and the underlying structures.

Adult↗

PubMed1991

A research tool for measurement of recovery from sedation: the Vancouver Sedative Recovery Scale.

The need for a research tool to measure recovery from sedation was identified during the design phase of a study investigating sedative protocols following open heart surgery in children. A thorough review of the literature failed to show any scales that measure degree of sedation in children at various times after initial awakening. The Vancouver Sedative Recovery Scale (VSRS) was developed through an iterative process during which we identified numerous indicators of levels of alertness among sedated children, and then determined the applicability and face validity of these indicators. The VSRS evaluated in this study consists of 12 distinct items that encompass three categories of indicators (response; eye appearance and function; and body movement). Total possible VSRS scoring ranges from 0 to 22 (higher score indicating more alert) because some of the 12 items have more than two rating levels. The VSRS was administered to 82 pediatric intensive care unit and postanesthesia recovery patients, with each patient assessed simultaneously by at least two observers. Internal consistency as measured by Cronbach's alpha was excellent: 0.85. Interobserver agreement or reliability as measured by intraclass correlation was also very high: 0.90; and for individual items Cohen's kappa ranged from 0.65 to 0.89. We consider the VSRS to be a good beginning in our effort to quantify level of alertness after sedation in the pediatric patient population.

Anesthesia Recovery Period↗

PubMed1991

Back pain and spinal changes in microgravity.

We believe that investigations into back pain and spinal changes in microgravity will contribute significantly to our knowledge and understanding of factors that cause back pain and the influence of spinal cord distraction on sensory and autonomic dysfunction. This information may have clinical implications for the treatment and rehabilitation of patients with spinal cord injury, for the care of patients during and after corrective spinal surgery, for the care and treatment of patients with chronic pain syndromes, and may potentially provide us with the opportunity to learn more about demyelinating diseases.

Back Pain↗

PubMed1989

Ingestion of cannabis: a cause of coma in children.

Previous reports of accidental ingestion of cannabis by children are rare. None has reported coma, although one described a stuporous state that required assisted ventilation. Over the past four years, the staff of British Columbia's Children's Hospital has managed six children with cannabis toxicity, three of whom presented in coma, including one with airway obstruction. Recurring diagnostic features included rapid onset of drowsiness, moderate pupil dilation, hypotonia, lid lag, and the presence of small granules or leaves in the mouth. Confirmation was obtained by positive urine screening for cannabinoids. The six cases described emphasize the need for emergency physician awareness of possible diagnostic criteria, the potential severity of intoxication, and the need for prevention through parent education.

Airway Obstruction↗

PubMedDate not supplied

The cost-benefit of pulse-oximeter use in the prehospital environment.

INTRODUCTION: Pulse-oximetry has proven clinical value in Emergency Departments and Intensive Care Units. In the prehospital environment, oxygen is given routinely in many situations. It was hypothesized that the use of pulse oximeters in the prehospital setting would provide a measurable cost-benefit by reducing the amount of oxygen used. METHODS: This was a prospective study conducted at 12 ambulance stations (average transport times > 20 minutes). Standard care protocols and paramedic assessments were used to determine which patients received oxygen and the initial flow rate used. Pulse-oximetry measurements (SpO2) were then taken. If SpO2 fell below 92% or rose above 96% (except in patients with chest pain), oxygen (O2) flow rates were adjusted. Costs of oxygen use were calculated: volume that would have been used based on initial flow rate; and volume actually used based on actual flow rates and transport time. RESULTS: A total of 1,907 patients were recruited. Oximetry and complete data were obtained on 1,787 (94%). Of these, 1,329 (74%) received O2 by standard protocol: 389 (27.5%) had the O2 flow decreased; 52 had it discontinued. Eighty-seven patients (6%) not requiring O2 standard protocol were hypoxemic (SpO2 < 92%) by oximetry, and 71 patients (5%) receiving oxygen required flow rate increases. Overall, O2 consumption was reduced by 26% resulting in a cost-savings of $0.20/patient. Prehospital pulse-oximetry allows unnecessary or excessive oxygen therapy to be avoided in up to 55% of patients transported by ambulance and can help to identify suboptimally oxygenated patients (11%). CONCLUSIONS: Rationalizing the O2 administration using pulse-oximetry reduced O2 consumption. Other health care savings likely would result from a reduced incidence of suboptimal oxygenation. Oxygen cost-saving justifies oximeter purchase for each ambulance annually where patient volume exceeds 1,750, less frequently for lower call volumes, or in those services where the mean transport time is less than the 23 minute average noted in this study.

Ambulances↗