Agaram G. Suryaprasad

Musculoskeletal responses of spinal cord injured individuals to functional neuromuscular stimulation-induced knee extension exercise training.

This study was conducted to evaluate a newly designed functional neuromuscular stimulation (FNS)-induced knee extension (KE) exercise system that incorporates the most desired features of previously described systems by determining the musculoskeletal responses of spinal cord injured (SCI) individuals to training. A specially designed chair and electrical stimulator were fabricated for FNS-induced KE resistance exercise. Surface electrodes were placed over motor points of the quadriceps muscles, and KE was alternated between legs at an average rate of 6 KE/min/leg. KE testing protocols were developed for pre- and post-training evaluations of performance, and 12 SCI subjects exercise-trained up to three times per week for 36 sessions using a progressive resistance load at ankle level. Pre- and post-training evaluation data were statistically compared using a 0.05 level for significance. Quadriceps muscle performance (strength x repetitions) improved for both legs in all subjects as indicated by significant increases in load resistance and repetitions over the 36-session training period (right leg mean = 1156.0 versus 1624.8 kg.reps, left leg mean = 1127.3 versus 1721.1 kg.reps). In addition, knee range of motion significantly increased (right leg mean = 134 versus 146 degrees, left leg mean = 133 versus 144 degrees). Thigh skinfold, thigh girth, body weight and bone density were not significantly changed. The lack of decrease in bone density in some subjects suggests that the training may retard the rate of bone loss which typically occurs with SCI. No injuries or problems were encountered during testing and training.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiologic responses of paraplegics and quadriplegics to passive and active leg cycle ergometry.

The purposes of this study were three-fold: (a) to determine acute physiologic responses of spinal cord injured (SCI) subjects to peak levels of leg cycle ergometry utilizing functional neuromuscular stimulation (FNS) of paralyzed leg muscles, (b) to determine the relative contributions of passive and active components of FNS cycling to the peak physiologic responses, and (c) to compare these physiologic responses between persons who have quadriplegia and those who have paraplegia. Thirty SCI subjects (17 quadriplegics and 13 paraplegics) performed a discontinuous graded FNS exercise test from rest to fatigue on an ERGYS 1 ergometer. Steady-state physiologic responses were determined by open-circuit spirometry, impedance cardiography with ECG, and auscultation. In the combined statistics of both groups, it was noted that peak FNS cycling significantly increased (from rest levels) mean oxygen uptake by 255%, arteriovenous O2 difference VO2 and VE, Q and a-vO2 and VCO by 69%, and stroke volume by 45%, while total peripheral vascular resistance decreased by 43%. Mean peak power output for paraplegics (15 W) was significantly higher than for quadriplegics (9 W), eliciting higher peak levels of pulmonary ventilation and sympathetically mediated hemodynamic responses such as cardiac output, heart rate, and systolic and diastolic arterial blood pressure. Passive cycling without FNS produced no statistically significant increases in physiologic responses above the resting level in either group.

Metabolic and hemodynamic responses to concurrent voluntary arm crank and electrical stimulation leg cycle exercise in quadriplegics

This study determined the metabolic and hemodynamic responses in eight spinal cord injured (SCI) quadriplegics (C5-C8/T1) performing subpeak arm crank exercise (ACE) alone, subpeak functional electrical stimulation leg cycle exercise (FES-LCE) alone, and subpeak FES-LCE concurrent with subpeak ACE (hybrid exercise). Subjects completed 10 minutes of each exercise mode during which steady-state oxygen uptake (VO2), pulmonary ventilation (VE), heart rate (HR), cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), arteriovenous oxygen difference (a-v O2 diff), and total peripheral resistance (TPR) were determined. Although mean VO2 for both ACE alone and FES-LCE alone was matched at 0.66 l/mi, individualized power outputs ranged from 0-30 W (mean = 19.4 +/- 1.3) and 0-12.2 W (mean = 2.3 +/- 0.6), respectively. Hybrid exercise elicited significantly higher VO2 (by 54 percent), VE (by 39-53 percent), HR (by 19-33 percent), and CO (by 33-47 percent), and significantly lower TPR (by 21-34 percent) than ACE or FES-LCE performed alone (P less than or equal to 0.05). Stroke volume was similar between hybrid exercise and FES-LCE alone, and these two exercise modes evoked a significantly higher SV (by 41-56 percent) than during ACE alone. These data clearly demonstrate that hybrid exercise creates a higher aerobic metabolic demand and cardiac-volume load in SCI quadriplegics than either subpeak levels of ACE or FES-LCE performed separately. Therefore, hybrid exercise may provide more advantageous central cardiovascular training effects in quadriplegics than either ACE or FES-LCE alone.

Acute hemodynamic responses of spinal cord injured individuals to functional neuromuscular stimulation-induced knee extension exercise

The purpose of this study was to determine and compare acute hemodynamic responses of spinal cord injured (SCI) quadriplegics (quads), and paraplegics (paras) during a graded-intensity knee extension (KE) exercise test utilizing functional neuromuscular stimulation (FNS) of paralyzed quadriceps muscles. Seven quads and seven paras (N = 14) performed a series of 4-minute stages of bilateral alternating FNS-KE exercise (approximately zero to 70 degree range of motion at the knee and 6 KE/min/leg) at ankle loads of 0, 5, 10, and 15 kg/leg. Physiologic responses were determined with open-circuit spirometry, impedance cardiography, and auscultation. Comparing rest with peak FNS-KE for both groups combined, FNS-KE exercise elicited significant (p less than 0.05) increases in oxygen uptake (130 percent), pulmonary ventilation (120 percent), respiratory exchange ratio (37 percent), arteriovenous oxygen difference (57 percent), cardiac output (32 percent), stroke volume (41 percent), mean arterial pressure (18 percent), and rate-pressure product (23 percent). Heart rate increased significantly by 11 percent from the 5- to the 15-kg/leg stages. Physiologic responses of quads and paras were very similar, except for lower (p less than 0.05) arterial pressures, rate-pressure product, and peripheral vascular resistance in quads. This graded FNS-KE exercise up to the 15-kg/leg load induced relatively small but appropriate increases in aerobic metabolism and cardiopulmonary responses that appear to be safe and easily tolerated by quads and paras. Arterial pressure needs to be monitored carefully in quads to prevent excessive hypertension or hypotension. Although FNS-KE exercise has been shown to elicit peripheral adaptations to improve muscle strength and endurance, it is probably not an effective central cardiovascular training tool for all but the least fit SCI individuals. This information is important for understanding the effects of FNS use during more complex activities such as cycling and ambulation.

Incidence of atheroembolic renal failure after coronary angiography: a prospective study.

Atheroembolic renal failure (AERF) is often seen after vascular procedures in elderly atherosclerotic patients. To estimate the incidence of AERF after coronary angiography, all patients undergoing coronary angiography at the V.A. Medical Center, Dayton, were prospectively evaluated for AERF. Since, unlike contrast nephropathy, AERF develops about a week after the vascular procedure and persists or progresses over weeks and months, serum creatinine was measured just prior to and 3 weeks after coronary angiog raphy. Peripheral signs of cholesterol emboli were also looked for at follow-up visits. Two hundred sixty-seven patients underwent coronary angiography over a fifteen-month period. Most of the patients were sixty years old or older. Mean serum creatinine in these patients prior to coronary angiography was 1.2 mg/dL. Mean serum creatinine after coronary angiography was unchanged (1.2 mg/dL) . Only 7 patients had serum creatinine > 2 mg/dL prior to coronary angiography. Two patients died within a week of coronary angiography and 2 did not return for follow-up. Of the remaining 263 patients, 5 had a serum creatinine increase by 0.5 mg/dL or more at three weeks after coronary angiog raphy. Three of 5 had a serum creatinine increase by 1.0 mg/dL or more. Two of these 3 patients eventually died of renal failure. None of these 5 patients had peripheral signs of cholesterol emboli. In selected patients, the incidence of AERF after coronary angiog raphy appears to be very low (<2%) .

Energy cost and cardiopulmonary responses for wheelchair locomotion and walking on tile and on carpet.

The purpose of this study was to compare energy cost and cardiopulmonary responses to wheelchair locomotion and walking on tile and on carpet at 3.0 km-h-1. Nine wheelchair-dependent (WD) and ten able-bodied (AB) individuals served as test subjects. WD subjects were tested for wheelchair locomotion on tile and on carpet, and AB subjects were tested for walking over both floor surfaces. Studied variables included gross energy cost (GEC), net locomotive energy cost (NLEC), pulmonary ventilation (VE) and heart rate (HR) during all test conditions. On tile, GEC and NLEC were found to be lower, whereas VE and HR were higher for wheelchair locomotion than for walking. On carpet, wheelchair locomotion elicited higher values for all variables than walking. In going from tile to carpet, significant increases in these variables were found for wheelchair locomotion, whereas walking elicited similar response magnitudes on both floor surfaces. These results suggest that cardiopulmonary stresses for wheelchair locomotion are higher than for walking, and that a carpet can present an obstacle to wheelchair locomotion which may not be recognised by those who walk.

An exercise test to evaluate fitness for wheelchair activity

The purpose of this study was to develop a wheelchair ergometer (WERG) test to evaluate fitness for manual wheelchair activity. Thirty able-bodied females participated in a progressive intensity, discontinuous test where exercise bouts were 4 min in duration interspersed with 5-min rest periods. Physiological responses of oxygen uptake (V02), respiratory exchange ratio (R), net mechanical efficiency (ME), pulmonary ventilation (VO) and heart rate (HR) were determined during the final minute of exercise at power output (PO) levels of 30, 60, 90, 120 and 150 kpm/min. These responses were generally found to be linearly related to PO, however, net ME initially increased with PO and plateaued at approximately 11 per cent at 90 kpm/min. Criteria for fitness evaluation were based upon: (1) magnitude of physiological responses at each PO level; and (2) the maximal PO level completed.

Efficiency of FNS leg cycle ergometry

The efficiency of electrically induced leg cycle ergometry performed by spinal-cord-injured (SCI) subjects was compared to voluntary leg cycle ergometry performed by able-bodied (AB) subjects at power output (PO) levels of 6-42 W. Twenty SCI (nine quadriplegics and 11 paraplegics) and twenty AB subjects exercised on a leg cycle ergometer. SCI subjects received functional neuromuscular stimulation (FNS) of paralyzed leg musculature, while AB subjects pedaled voluntarily. Subjects performed a discontinuous, progressive intensity exercise test with 6-W (for SCI) or 12-W (for AB) PO increments between stages. Each exercise bout was 5 min in duration and was followed by a 5-min rest period. Steady-rate oxygen uptake (VO/sub 2/) and respiratory exchange ratio (RER) values were determined by open-circuit spirometry during the final minute of each stage. Gross, net, work, and data efficiencies were calculated for each PO. These efficiencies ranged from 2 to 14% for FNS cycling by SCI subjects and from 4 to 34% during voluntary cycling by AB subjects. At most POs, efficiencies for FNS cycling were significantly lower (by approximately one-half) than those for voluntary cycling. Despite the apparent energy-wastefulness or inefficiency of FNS leg cycle ergometry, the relatively high metabolic rates elicited by the exercise may be advantageous to SCI individuals seeking aerobic (cardiopulmonary) training effects.<<ETX>>

Mechanical hemolytic anemia after repair of ruptured chordae tendineae of mitral valve apparatus.

A case of mechanical hemolytic anemia following mitral valvuloplasty for ruptured chordae tendineae is described. We postulate that intravascular hemolysis is the result of whiplash motion caused by the loose ends of the ruptured chordae tendineae and the disrupted suture material attached to the mitral valve apparatus.

Physiologic responses of SCI subjects to electrically induced leg cycle ergometry

The purpose of this study was to determine steady-state physiologic responses of spinal-cord-injured (SCI) subjects to electrically induced leg-cycle ergometry, and to compare these responses to those of able-bodied (AB) individuals performing voluntary leg-cycle ergometry at the same power output (PO) levels. Twelve SCI subjects and 6 AB subjects exercised on a microprocessor-controlled functional neuromuscular stimulation (FNS) cycle ergometer. FNS of paralyzed leg muscles was delivered via skin-surface electrodes over the quadriceps, hamstring, and gluteal muscle groups. Subjects performed several 5-min bouts of progressive intensity cycling (6- or 12-W increments) at 50 r.p.m. Each bout was followed by a 5-min rest period. Oxygen uptake, pulmonary ventilation, and heart rate were significantly higher for the SCI group at each PO level. The data suggest that this FNS exercise may elicit metabolic and cardiopulmonary responses from FNS-trained SCI individuals that are of similar magnitudes to those elicited from AB individuals during jogging exercise. The authors therefore hypothesize that this mode of FNS exercise training may promote higher levels of aerobic fitness in many SCI individuals than can be obtained by conventional arm exercise (e.g. wheelchair propulsion, cranking).<<ETX>>