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B McFadyen

Publications and source records attributed to B McFadyen.

7 recordsLinked to original sources
PubMed2005

Movement patterns and muscular demands during posterior transfers toward an elevated surface in individuals with spinal cord injury.

STUDY DESIGN: Three-dimensional kinematic analysis and surface electromyography (EMG) of 10 male adults with complete spinal cord injury (C7 to L2). OBJECTIVE: To examine movement patterns and muscular demands in individuals with spinal cord injury (SCI) during posterior transfers. SETTING: Pathokinesiology Laboratory at a Rehabilitation Centre, Montreal, Canada. METHODS: Kinematic variables that described the positions and angular displacements of the head, trunk, shoulder and elbow were obtained by videotaping markers placed on the subject segments. EMG data were recorded for the biceps, triceps, anterior deltoid, pectoralis major, latissimus dorsi and trapezius muscles of the dominant upper extremity during posterior transfers using surface electrodes. To quantify the muscular demand, the EMG data recorded during the transfers were normalized to values obtained during maximal static contractions (EMGmax). The mean muscular demand was calculated for every muscle during the lift phase of the transfers. The lift phase was determined by pressure-sensitive contacts. RESULTS: All subjects were able to execute the posterior transfers on an even surface, whereas nine subjects completed at least one of the transfers to the elevated surface. A forward-flexion pattern at the head and trunk was observed when either one or two hands remained on the lower surface, whereas a lift strategy was seen when both hands were placed on the elevated surface. Transferring to the elevated surface with hands on the lower surface required inferior electromyographic muscular utilization ratio (EMUR) than the transfer on the even surface for all muscles. The lowest EMUR were calculated for the transfer to the elevated surface with hands on the lower surface (triceps (18%), pectoralis major (53.8%), trapezius (66%) and latissimus dorsi (24.5%)) while performing the same transfer with hands on the elevated surface generated the highest EMUR (triceps (40.2%), anterior deltoid (73.2%), trapezius (83.6%) and latissimus dorsi (55.3%)). CONCLUSIONS: Subjects presented different movement characteristics and muscular demands during the posterior transfers. It is suggested that the forward-flexion pattern improves the dynamic trunk stability and reduces the muscular demand required to transfer. High muscular demand developed when hands were positioned on the elevated surface might be due to increased postural control demands on the upper limb and reduced angular momentum.

Adult↗
PubMed2005

Severe hypothermia: challenging normal physiology.

Accidental hypothermia is not a frequent cause of death in Australia. Moreover it is rare to have an admission to hospital with a core temperature below 32 degrees C. Among the cases described in the literature, it is clear that temperature and prognosis are related. Our patient presented with severe accidental hypothermia and even though the admission core temperature was below 26 degrees she was successfully discharged from hospital after active re-warming with three different devices. She had laboratory and ECG findings associated with severe hypothermia.

Aged↗
PubMed2003

Simulated epidural test doses using adrenaline and adrenaline/clonidine in sevoflurane-anaesthetized children.

A pilot study was conducted using a simulated epidural test dose to ascertain the effects adrenaline, adrenaline/clonidine mixture, and clonidine alone on the accepted criteria for determining the occurrence of an epidural intravascular injection. Seventy-five ASA 1 or 2 children aged from six months to twelve years were sequentially allocated to one of three groups: group A: adrenaline 0.5 microgram/kg, group AC: adrenaline 0.5 microgram/kg and clonidine 0.3 microgram/kg, and group C: clonidine 0.3 microgram/kg. Effects on heart rate, T-wave amplitude and systolic blood pressure were determined after induction of anaesthesia and stabilization using sevoflurane in nitrous oxide and oxygen. Heart rate varied from baseline in a biphasic manner. The maximal increase in mean heart rate for all groups was < 10 beats per minute (bpm). A heart rate rise of > 10 bpm was not seen at any time in 54% of groups A and AC and 92% of group C (Chi-square 11.4, P = 0.003). T-wave changes were also biphasic. 50% of groups A and AC had no increase in T-wave size of > 25% at any sample point, compared with 96% in group C (Chi square = 49.4, P < 0.0001). 34% of groups A and AC did not have a change in systolic blood pressure of > 15 mmHg during the study compared with 100% of group C (Chi-square = 30.2, P < 0.0001). There were no significant differences between groups A and AC for any parameter. Negative predictive value estimates for the current criteria for intravascular injection were low. Clonidine 0.3 microgram/kg produced no effects on the study variables.

Adrenergic alpha-Agonists↗
PubMed1995

A kinematic and kinetic analysis of locomotion during voluntary gait modification in the cat.

As part of a study to characterize the postural reactions that occur during voluntary gait modification, we examined the kinematic, electromyographic (EMG), and kinetic responses that occurred when cats stepped over an obstacle placed in their path. Analyses of the kinematics as each of the forelimbs stepped over the obstacle showed that changes in joint angles were most pronounced at the elbow of the first (lead) limb, and at the shoulder of the second (trailing) limb. In the hindlimbs, there was a pronounced change in the knee joint angle in both the leading and trailing limbs. Examination of the horizontal and vertical velocities of the tip of the forepaw suggests that the movements can be divided into two phases: one in which the limb is rapidly lifted above and over the obstacle, and a slower one during which the limb is carefully repositioned on the floor. On the basis of the velocity profiles, we suggest that the repositioning of the paw on the support surface is more critically controlled for the forelimb than for the hindlimb. Analysis of the changes in the ground reaction forces in the supporting limbs during these gait modifications showed that there were two major increases in vertical reaction force. One of these occurred as the two forelimbs were straddling the obstacle, the other when the two hindlimbs were straddling it. There was also a net increase in the anteroposterior force that resulted in a small increase in propulsion as the cat stepped over the obstacle. Each change in the vertical ground reaction force was paralleled by a similar change in the amplitude of the EMG recorded from the respective extensor muscles. An analysis of the vertical displacement of the scapula and of the pelvis showed that there was a slight increase in the height of the scapula in the support limb just prior to and during the swing phase of the trailing forelimb, and a more pronounced and progressive change in the height of the pelvis prior to and during the passage of both hindlimbs over the obstacle. We suggest that the increases in vertical ground reaction force raise the height of the body sufficiently to allow, respectively, passage of the trail forelimb and each of the hindlimbs over the obstacle. The results are discussed with respect to both the biomechanical changes underlying these gait modifications and the neuronal mechanisms implicated in their control.

Animals↗
PubMed1992

The organization of stepping in patients with Parkinson's disease: bradykinesia or discoordination?

The purpose of this experiment was to quantify and analyse multijoint coordination of patients with Parkinson's disease (N = 5) and control subjects (N = 5) during forward and backward stepping motions executed at different cadences. Coordinates of reflective markers placed on the shoulder, hip, knee, ankle and metatarsal joints were recorded in the sagittal plane using a video motion analysis system. Kinematic and kinetic analyses provided angular displacements and velocities as well as joint moments of force and powers. Results suggest the presence of two types of discoordination: one type is velocity-dependent, hence related to bradykinesia, whereas the other type appears to reflect qualitatively different coordination patterns.

Aged↗
PubMed1987

Normative childhood EMG gait patterns.

The population characteristics of the linear envelopes of the electromyograms measured from seven lower extremity muscles in children were studied during locomotion. The variability and changes in pattern with respect to walking speed and age were investigated using statistical properties and analysis of variance of the envelopes. All muscles studied showed changes in their patterns that were associated with different walking speeds. Some changes concerned the relative intensity of existing phases of activity whereas others concerned the existence of additional phases of activity. The most remarkable trend was that all envelopes tended to have more consistent patterns as speed increased. With regard to age, within the span of 4-11 years, only the two thigh muscles studied demonstrated appreciable differences.

Age Factors↗