Biomedical subjects

G M Bogdanffy

Publications and source records attributed to G M Bogdanffy.

4 recordsLinked to original sources

PubMed1998

Aerobic and anaerobic energy expenditure during exhaustive ramp exercise.

Ramp tests are often manipulated so that oxygen uptake is able to interpret energy expenditure in its entirety. We hypothesized that oxygen deficits during ramp exercise to exhaustion would be significant, providing a more complete description of the types of energy expenditure available for this mode of testing. Oxygen deficits were obtained during a slow ramp (681 +/- 71 s) and a fast ramp (275 +/- 33 s) to exhaustion. Twelve healthy men (age 35 +/- 3 yrs; VO2max 51 +/- 10 ml x kg(-1) x min(-1)) performed several 10 min submaximal bike rides (at or below ventilatory threshold) to determine work rate -O2 uptake demands. Estimated O2 demands were compared to measured O2 uptake during each ramp test, the difference representing an oxygen deficit. Work levels were controlled and measurements collected with a commercially available electrically braked bike ergometer and metabolic testing system (MedGraphics, Minn., MN). Data were collected and averaged in 30 s time periods, power in watts (W), energy expenditure in cumulative O2 (L). Using a paired t-test, cumulative O2 uptakes were significantly lower (p = 0.0001) when measured O2 uptakes (26.0 L +/- 4.5 for slow ramp; 10.8 L +/- 2.8 for fast ramp) were compared to estimated O2 demands (29.0 L +/- 3.7 for slow ramp; 14.1 L +/- 3.5 for fast ramp). Anaerobic energy expenditures (oxygen deficits) represented 10.8% and 23.4% of total energy expenditure for slow ramps and fast ramps, respectively. Comparisons of the slopes for each test condition revealed significant differences (steady state > slow ramp > fast ramp; p = 0.0001,ANOVA). We conclude that the oxygen deficit during ramp testing represents a significant part of total energy expenditure.

Adult↗

PubMed1996

Prospective outcome evaluation of spinal cord stimulation in patients with intractable leg pain.

STUDY DESIGN: The results of spinal cord stimulation were prospectively evaluated using both subjective patient self-report measures and objective physical functional testing. OBJECTIVES: The purpose of this study was to evaluate prospectively the effects of spinal cord stimulation implantation, performed with the patient awake and providing feedback, in patients with primary reports of intractable leg pain. SUMMARY OF BACKGROUND DATA: Spinal cord stimulation has been used for treating chronic pain of many types. However, even among those with intractable lower extremity pain, the outcome results have shown great variability. METHODS: The surgical procedure was performed with the patient awake and providing feedback to ensure optimal pain relief from the lead placement. The study group comprised 40 patients, ranging in age from 28 to 86 years. The average symptom duration was 65.4 months, and the average number of prior lumbar spine surgeries was 2.3 (range, 1 to 8). The primary data collection periods were preoperative, 6 weeks after, and 12 and 24 months after surgery. RESULTS: Statistically significant improvement in isometric lower extremity function was demonstrated 6 weeks after the spinal cord stimulation implantation. In the more painful leg, the performance increased from 457.5 ft-lb-sec to 629.8 ft-lb-sec (P < 0.01). The performance remained significantly improved at the 12- and 24-month follow-ups. Significant improvement was demonstrated on the physical scale of the Sickness Impact Profile at 6 weeks. At 24 months, all three scales (physical, psychological, and other) as well as the total score were significantly improved. Statistically significant decreases in pain, assessed by changes in visual analog scale scores, were noted in the legs, when walking, and in overall lifestyle. The use of narcotic medication decreased at all follow-up periods. At least 66% of the patients who were taking narcotics before spinal cord stimulation were taking reduced amounts or no narcotics 2 years later. At the time of the 24-month follow-up, at least 70% of patients reported that the procedure helped them, and would recommend it to someone with similar symptoms. CONCLUSIONS: Spinal cord stimulation implantation can result in improved physical function and decreased pain in patients who are carefully screened and in whom the implantation is performed with the patient awake to help ensure optimal pain-relieving lead placement.

Adult↗

PubMed1995

Early changes in bone mineral density above a combined anteroposterior L4-S1 lumbar spinal fusion. A clinical investigation.

STUDY DESIGN: Fifteen patients meeting rigid study entrance criteria for undergoing a combined anteroposterior L4-S1 spinal fusion as a first time operation were included in the study. Bone mineral density changes at adjacent segments (L3 and L2) were assessed by scanning patients in the anteroposterior and lateral projections before surgery and 3 and 6 months after surgery. OBJECTIVES: To prospectively evaluate changes in bone mineral density at adjacent segments after lumbar spinal fusion and postoperative bracing. SUMMARY OF BACKGROUND DATA: The majority of studies investigating changes in bone mineral density after spinal fusion have been performed in canines. Although such work has provided valuable insight, its application to humans is questionable because the loading mechanics are so different. METHODS: Bone mineral density was assessed noninvasively by dual energy x-ray absorptiometry in the lateral and anteroposterior projections. Data were analyzed with special edge detection software. RESULTS: In the lateral projection at L3, one level above the fusion, the preoperative bone mineral density was 0.91 +/- 0.24 (mean +/- standard deviation in g/cm2). This decreased significantly at 3 months to 0.82 +/- 0.24 and remained reduced at 6 months (0.80 +/- 0.21). This reflected a loss of primarily trabecular bone. In the anteroposterior projection at L2, there was a significant loss at 3- and 6-month follow-up (1.24 +/- 0.15 to 1.19 +/- 0.15 and 1.19 +/- 0.14). This may reflect changes at either or both of the anterior and posterior columns. CONCLUSION: Significant decreases in bone mineral density were noted above fused lumbar segments. This may have been related to immobilization or altered mechanics associated with arthrodesis. Trabecular bone of the axial skeleton is most responsive to change, compared with cortical bone, because of the higher metabolic activity. This may explain the reduction of bone mineral density at L3. Changes at L2 may have been related to altered loads at the anterior or posterior columns and should be further investigated.

Adult↗

PubMed1990

Effect of a practical neck cooling device on core temperature during exercise.

Previous studies have documented the effectiveness of combined head and neck cooling in reducing thermal stress during exercise. However, these studies investigated low intensity exercise and devices that are not practical for use on a widespread basis during recreational exercise. In the present study, we investigated the effect of a commercially available, practical neck cooling device on core temperature during strenuous exercise. In a randomized cross-over fashion, 10 male endurance athletes (age 29 +/- 2 yr) performed a 45-min submaximal run (Borg rating of perceived exertion approximately 15) at a constant speed, with and without neck cooling. Runs were conducted on an indoor track, where the ambient temperature was maintained at approximately 21 degrees C dry bulb and approximately 17 degrees C wet bulb. Exercise heart rates and subjective perception of effort were not significantly modified by neck cooling. In contrast, rectal temperature rises (by 0.21 degrees C or 9.5%, P less than 0.02) and sweat rates (by 92 ml.h-1 or 6.4%, P less than 0.02) were reduced by neck cooling. Our study therefore concludes that this practical neck cooling device is capable of inducing reductions in thermal stress during strenuous exercise that, although numerically small, are in a direction of potential benefit.

Adult↗