Biomedical subjects

P D Faghri

Publications and source records attributed to P D Faghri.

8 recordsLinked to original sources

PubMed2005

Kinematic analyses of semireclined leg cycling in able-bodied and spinal cord injured individuals.

STUDY DESIGN: Retrospective descriptive study. OBJECTIVES: To evaluate the leg kinematics and motion characteristics within able-bodied (AB) and spinal cord injured (SCI) individuals during stationary semireclined cycling. SETTING: Functional Performance Laboratory, Connecticut, USA. METHODS: Three SCI and three AB subjects participated in steady-state leg pedaling (50 revolutions per minute). The SCI group participated in electrical stimulation (FES)-induced cycling at resistances of 0, 6.25, and 12.5 Watts (W). The AB group cycled on the same ergometer without FES at resistances of 0, 60, and 120 W. Motion capture analysis recorded joint angular position, velocity, and acceleration at hip, knee, and ankle. Joint kinematics of hip, knee, and ankle were measured during steady-state leg cycling and comparisons were made between AB and SCI subjects as resistance proportionally and relatively increased. RESULTS: Intrasubject hip and knee movement patterns showed minimal variability across resistance levels. Comparisons between AB and SCI subjects showed that the hip and knee kinematics were very similar at all resistance levels. However, ankle movement patterns appeared to increase in variability (increased dorsiflexion) with increased resistance level in AB subjects and less so with SCI subjects. Overall, the ankle kinematics for AB and SCI subjects were dissimilar at resistance levels greater than zero. CONCLUSIONS: The joint kinematics of the hip, knee, and ankle were found to be periodic, but the differences in ankle kinematics in AB and SCI subjects suggest more emphasise should be placed on the current design of the bike-pedal and subject-specific seat configurations.

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PubMed2001

Circulatory hypokinesis and functional electric stimulation during standing in persons with spinal cord injury.

OBJECTIVE: To evaluate the effects of functional electric stimulation (FES) of lower limb muscles during 30 minutes of upright standing on the central and peripheral hemodynamic response in persons with spinal cord injury (SCI). DESIGN: A repeated-measure design. Subjects were used as their own control and underwent 2 testing protocols of FES-augmented standing (active standing) and non-FES standing (passive standing). SETTING: Rehabilitation hospital. PARTICIPANTS: Fourteen individuals with SCI (7 with tetraplegia, 7 with paraplegia). INTERVENTIONS: During active standing, FES was administered to 4 muscle groups of each leg in an overlapping fashion to produce a pumping mechanism during standing. During passive standing, subjects stood for 30 minutes using a standing frame with no FES intervention. MAIN OUTCOME MEASURES: Central hemodynamic responses of stroke volume, cardiac output, heart rate, arterial blood pressure, total peripheral resistance (TPR), and rate pressure product (RPP) were evaluated by impedance cardiography. All measurements were performed during supine and sitting positions before and after standing, and during 30 minutes of upright standing. RESULTS: Comparisons between the groups with paraplegia and tetraplegia showed a significant increase in heart rate in the paraplegics after 30 minutes of active standing. During active standing, paraplegics' heart rate increased by 18.2% (p = .015); during passive standing, it increased by 6% (p = .041). TPR in the tetraplegics significantly (p = .003) increased by 54% when compared with the paraplegics during passive standing. Overall, the tetraplegic group had a significantly lower systolic blood pressure (p = .013) and mean arterial pressure (p = .048) than the paraplegics during passive standing. These differences were not detected during active standing. When data were pooled from both groups and the overall groups response to active and passive standing were compared, the results showed that cardiac output, stroke volume, and blood pressure significantly decreased (p < .05) during 30 minutes of passive standing, whereas TPR significantly increased (p < .05). All of the hemodynamic variables were maintained during 30 minutes of active standing, and there were increases in RPP and heart rate after 30 minutes of active standing. CONCLUSION: FES of the lower extremity could be used by persons with SCI as an adjunct during standing to prevent orthostatic hypotension and circulatory hypokinesis. This effect may be more beneficial to those with tetraplegia who have a compromised autonomic nervous system and may not be able to adjust their hemodynamics to the change in position.

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PubMed1998

Venous hemodynamics of the lower extremities in response to electrical stimulation.

OBJECTIVE: To evaluate the calf muscle pump function using an air plethysmograph (APG) applied to the lower leg of subjects during three different tiptoe exercises. DESIGN: A controlled trial design was selected to compare the hemodynamic effects of three exercise conditions on a group of able-bodied, healthy patients. SETTING: Testing was performed in an outpatient clinic at a rehabilitation hospital. SUBJECTS: Patient groups were selected from a convenience sample of 10 healthy volunteers with normal venous capacitance and no reflux, determined through impedance pleythysmography before the study. INTERVENTIONS: Three exercise conditions undertaken by each subject consisted of loaded and unloaded lower leg muscle contractions produced by (1) voluntary contraction (VOL), (2) electrical stimulation of the gastocnemius-soleus and tibialis anterior muscles (ES), and (3) combined ES and VOL (ES/VOL). MAIN OUTCOME MEASURE: Hemodynamic measurements of venous filling index upon standing from the supine (VFI), ejection fraction (EF), ejection volume (EV), residual volume (RV), and residual volume fraction (RVF) were recorded after each protocol. These results were used to compare the lower leg hemodynamic effects of the treatments. RESULTS: Combined ES/VOL single tiptoe exercise produced the highest EV (97.8mL), followed by VOL (80.6mL) and ES (51.7mL) (p < .0008). The EF was also highest for combined ES/VOL (73.1%), followed by VOL (64.5%) and ES (37.8%) (p < .0001). Ten tiptoe ES exercises produced the highest RV (96.2mL), followed by ES/VOL (44.7mL) and VOL (28.2mL) (p < .0001). RVF was also highest in the ES group (71%), followed by ES/VOL (33.4%) and VOL (22.8%) (p < .0001). CONCLUSION: Periodic single ES-induced calf muscle contractions produced significant muscle pump function and could be used to improve venous blood flow and reduce stasis in the lower leg. Continuous ES-induced contractions, on the other hand, could improve lower leg peripheral perfusion while eliciting the physiologic venous muscle pump. Higher RV and RVF after 10 ES-induced contractions in this sample of healthy subjects with normal VFI may be caused by an increase in arterial blood perfusion after repeated ES-induced contractions.

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PubMed1997

Electrical stimulation-induced contraction to reduce blood stasis during arthroplasty.

Deep venous thrombosis and subsequent pulmonary embolism due to venous pooling/stasis commonly occur in patients during hip and/or knee arthroplasty (i.e., replacement). This problem may be alleviated by using techniques to promote lower limb blood flow. Electrical stimulation-induced contractions have been shown to activate the skeletal muscle pump, promote limb blood flow, and may be effective for reducing venous pooling/stasis and edema. Therefore, electrical stimulation may reduce the incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) during and following surgery. The overall goal of this project was to evaluate the clinical efficacy of sequential electrical stimulation-induced leg muscle contractions on the venous blood flow during surgery. The degree of venous pooling/stasis was monitored via electrical impedance changes in the thorax. The changes in the patient's central hemodynamics were then calculated. Thirty patients were recruited and randomly assigned to either a control group (n = 15, mean age = 66.4 +/- 7.3) or experimental group (n = 15, age = 60.7 +/- 9.7). Both groups received the standard medical treatment for prevention of DVT (i.e., coumadin, heparin, etc.) and compression stockings (TED, Kendall). The control group used the sequential compression device (SCD + TED) and the experimental group used electrical stimulation (ES + TED). Electrical stimulation was applied via surface electrodes to the lower-limb muscles (tibialis anterior and gastrocnemius) and upper limb muscles (quadriceps femoris and hamstrings). These muscles contracted sequentially, using an eight-channel electrical stimulator. Four seconds of calf (contraction/compression) were followed by 7-s of calf and thigh (contraction/compression) interspersed by 60-s rest period during both electrical stimulation or sequential compression device. This cycle continued throughout the surgery (60-75 min) for both groups. At 15 min intervals, venous return was monitored by impedance cardiograph. Physiologic responses including ventricular stroke volume (SV), cardiac output (CO), heart rate (HR), total peripheral resistance (TPR), as well as mean arterial pressure (MAP) were monitored. These responses were statistically analyzed and compared throughout the surgery within each group and between the two groups. The results show stroke volume and cardiac output to be higher throughout surgery in the electrical stimulation group as compared with the sequential compression device group. The heart rate was consistently lower during electrical stimulation for both groups. Total peripheral resistance did not change in the electrical stimulation group; but increased in the sequential compression device group. The data suggest that continuous electrical stimulation-induced contractions could improve lower leg circulation by eliciting the physiologic muscle pump. This will lead to improved venous circulation and reduction of blood stasis during total hip and/or knee surgery. This technique may offer greater protection against DVT and PE during surgery than the commonly used sequential compression device.

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PubMed1994

The effects of functional electrical stimulation on shoulder subluxation, arm function recovery, and shoulder pain in hemiplegic stroke patients.

The purpose of this study was to evaluate the effectiveness of a functional electrical stimulation (FES) treatment program designed to prevent glenohumeral joint stretching and subsequent subluxation and shoulder pain in stroke patients. Twenty-six recent hemiplegic stroke patients with shoulder muscle flaccidity were randomly assigned to either a control group (n = 13; 5 female, and 8 male) or experimental group (n = 13; 6 female, and 7 male). Both groups received conventional physical therapy. The experimental group received additional FES therapy where two flaccid/paralyzed shoulder muscles (supraspinatus and posterior deltoid) were induced to contract repetitively up to 6 hours a day for 6 weeks. Duration of both the FES session and muscle contraction/relaxation ratio were progressively increased as performance improved. The experimental group showed significant improvements in arm function, electromyographic activity of the posterior deltoid, range of motion, and reduction in subluxation (as indicated by x-ray) compared with the control group. We concluded that the FES program was effective in reducing the severity of shoulder subluxation and pain, and possibly facilitating recovery of arm function.

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PubMed1992

Functional electrical stimulation leg cycle ergometer exercise: training effects on cardiorespiratory responses of spinal cord injured subjects at rest and during submaximal exercise.

This study investigated the cardiorespiratory (CR) responses at rest and during submaximal (0-W) functional electrical stimulation (FES)-induced leg cycle ergometer (LCE) exercise prior to and following a progressive intensity FES-LCEa exercise training program in spinal cord injured (SCI) subjects. Seven quadriplegics and six paraplegics participated in FES-LCE training three sessions per week for approximately 12 weeks (36 sessions). Monitored CR responses, including oxygen uptake (VO2), pulmonary ventilation (VE), respiratory exchange ratio (RER), arteriovenous O2 difference (a-vO2), blood pressure (BP), heart rate (HR), stroke volume (SV), total peripheral resistance (TPR), and cardiac output (Q), were determined before and after training. Power output (PO) increased significantly (p < .05) over the duration of the training program, indicating increased in strength and endurance of the paralyzed muscles used. Respiratory responses were not significantly altered by training in both groups. FES-LCE training significantly increased resting HR and SBP in quadriplegics and lowered SBP, DBP, and MAP in paraplegics. In both groups, HR and BP during submaximal exercise significantly decreased and SV and Q significantly increased after completion of the training program. These results suggest that FES-LCE training improves peripheral muscular and central cardiovascular fitness in SCI subjects. Posttraining HR and BP may also be more stable in quadriplegics and alleviate hypotension. This therapeutic exercise may ultimately lead to improved rehabilitation outcome and reduced stress during activities of daily living, and possibly reduce the risks for secondary CR disabilities.

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PubMed1990

Physiologic responses to prolonged electrically stimulated leg-cycle exercise in the spinal cord injured.

This study determined the physiologic responses to prolonged functional neuromuscular stimulation (FNS) leg-cycle exercise in seven quadriplegic and seven paraplegic subjects. Each subject completed 30 minutes of continuous FNS leg cycling during which open-circuit spirometry, impedance cardiography, auscultation, and fingertip capillary blood sampling were used to assess metabolic and hemodynamic responses. Compared with resting values, oxygen uptake, carbon dioxide production, respiratory exchange ratio (RER), pulmonary ventilation, heart rate (HR), left ventricular stroke volume (SV), cardiac output (Qt), and blood lactate (La) concentration were significantly (p less than .05) elevated, whereas plasma volume, bicarbonate concentration, and pH were significantly decreased in both groups during prolonged FNS leg-cycle exercise. Mean arterial pressure remained unchanged in quadriplegic and paraplegic subjects during the prolonged FNS leg-cycle exercise bout. Persons with quadriplegia elicited significantly lower MAP and tended to have lower SV and Qt responses than persons with paraplegia, probably due to a higher degree of sympathetic dysfunction and circulatory hypokinesis during FNS leg-cycle exercise. All other physiologic variables responded similarly between groups. We speculate that the relative increases observed for HR (33% to 60%), SV (45% to 69%), and Qt (113% to 142%) during prolonged FNS leg-cycle exercise create a sufficient cardiac-volume load to promote central cardiovascular conditioning in persons with both quadriplegia and paraplegia. The La accumulation (4.7 to 5.2 mmol.L-1) in the spinal cord injured during prolonged FNS leg cycling is unusually high for the power output attained (5.2W and 6.1W for quadriplegia and paraplegia, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

The effects of neuromuscular stimulation-induced muscle contraction versus elevation on hand edema in CVA patients.

The purpose of this study was to evaluate the efficacy of the use of neuromuscular stimulation (NMS)-induced contraction of the paralyzed muscles to produce an active muscle pump for removing excess fluid and compare its effect with elevation of the upper extremity. The effects of 30 minutes of NMS of the finger and wrist flexors and extensors were compared with the effects of 30 minutes of limb elevation alone. Each of eight cerebrovascular accident (CVA) patients with visible hand edema received both treatments, one on each of 2 consecutive days. Measures of hand and arm volume and upper and lower arm girth were taken before and after each treatment. Analyses comparing mean percentage change scores for both treatments showed large and significant treatment effects for all dependent measures. The finding suggests that NMS was more effective for reduction of hand edema than limb elevation alone for this sample of eight CVA patients.

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