Effect of heat modalities on hamstring length: a comparison of pneumatherm, moist heat pack, and a control.

STUDY DESIGN: Prospective, researcher-blinded, repeated-measures, randomized complete block design. OBJECTIVES: To compare the effects of a single treatment of Pneumatherm, moist heat pack, and a control treatment on hamstring muscle length. BACKGROUND: Traditionally, heating modalities have been used to facilitate increases in tissue length. The Pneumatherm has been developed over the past 20 years for use in the clinical treatment of a variety of musculoskeletal pathologies. However, there is no published evidence supporting the use of Pneumatherm for improving muscle length. SUBJECTS: Participants consisted of 30 healthy, college-age males taken from a convenience sampling from the University of Indianapolis student population. METHODS AND MEASURES: Participants received a 3-treatment sequence on consecutive days. Treatments involved applying the determined modality to the posterior thigh using standard treatment protocols. A hand-held dynamometer was used to establish a consistent passive measurement force to measure hamstring muscle length. RESULTS: A mixed-model analysis of variance with pretest-posttest (3 pretest and 3 posttest measures) and treatment sequence of the modalities (6 sequences of Pneumatherm, moist heat, and control) was completed. The only significant effect was for pretest-posttest measures. Post hoc comparisons revealed that the Pneumatherm posttest value was significantly different from all other measures. There were no differences found between pretest scores and the moist heat and control posttest scores. CONCLUSIONS: Our results demonstrate that the Pneumatherm modality is an effective agent for increasing hamstring muscle length following a single 20-minute treatment. In this study, a significant gain in hamstring muscle length was not found following a 1-time treatment with moist heat. The Pneumatherm may be a good option when heat is used to assist in gaining flexibility of the hamstring musculature.

Development and characterization of an infection inhibiting urinary catheter.

Catheter associated bacturia is common in hospitals and nursing homes. The objective of this study was to develop an infection inhibiting urinary catheter for prolonged use. Methods were established to add chlorhexidine digluconate (CHG) to a silicone elastomer and to compression mold the material to form a urinary catheter. CHG was randomly dispersed in the elastomer to be released through elution. Samples of the material, with CHG concentrations ranging from 1 to 4% by weight, were tested for in vitro release characteristics over a 28 day period and for in vivo toxicity over a 7 day period. Release profiles followed a common pattern for each concentration: an initial peak during the first 24 hours was followed by a subsequent decline. CHG amounts released into the saline medium were directly related to the CHG concentration of the samples; 4% samples released the largest amounts and 1% samples released the least amounts. Both 3% and 4% CHG by weight samples released measurable amounts of CHG throughout the entire observation period, whereas 1% CHG by weight samples were depleted after 9 days, and 2% CHG by weight samples were depleted after 19 days. No samples were found to be toxic during in vivo evaluations. These studies suggest that CHG bearing silicone rubber urinary catheters could resist surface colonization and infection for extended periods without toxicity.

INTRACORPOREAL HEAT DISSIPATION FROM A RADIOISOTOPE-POWERED ARTIFICIAL HEART.

The feasibility of radioisotope-fueled circulatory support systems depends on the ability of the body to dissipate the reject heat from the power source driving the blood pump as well as to tolerate chronic intracorporeal radiation. Our studies have focused on the use of the circulating blood as a heat sink. Initial in vivo heat transfer studies utilized straight tube heat exchangers (electrically and radioisotope energized) to replace a segment of the descending aorta. More recent studies have used a left ventricular assist pump as a blood-cooled heat exchanger. This approach minimizes trauma, does not increase the area of prosthetic interface with the blood, and minimizes system volume. Heat rejected from the thermal engine (vapor or gas cycle) is transported from the nuclear power source in the abdomen to the pump in the thoracic cavity via hydraulic lines. Adjacent tissue is protected from the fuel capsule temperature (900 to 1200 degrees F) by vacuum foil insulation and polyurethane foam. The in vivo thermal management problems have been studied using a simulated thermal system (STS) which approximates the heat rejection and thermal transport mechanisms of the nuclear circulatory support systems under development by NHLI. Electric heaters simulate the reject heat from the thermal engines. These studies have been essential in establishing the location, suspension, surgical procedures, and postoperative care for implanting prototype nuclear heart assist systems in calves. The pump has a thermal impedance of 0.12 degrees C/watt. Analysis of the STS data in terms of an electrical analog model implies a heat transfer coefficient of 4.7 x 10(-3) watt/cm(2) degrees C in the abdomen compared to a value of 14.9 x 10(-3) watt/cm(2) degrees C from the heat exchanger plenum into the diaphragm.