Biomedical subjects

Arthur T Johnson

Publications and source records attributed to Arthur T Johnson.

11 recordsLinked to original sources

PubMed2007

How far can one walk wearing a self-contained self rescuer?

Self-contained self rescuers (SCSRs) are used for emergency escapes in oxygen-deficit atmospheres. Certified by NIOSH to last 1 hour, SCSRs generate oxygen by chemical reaction and must meet a minimum oxygen generation time of 60 min when used according to instructions. Wearers must walk or crawl at a controlled rate to conform to the limits of the devices. The aim of the is study was intended to determine the distance that can be walked when using SCSRs as intended. Fourteen volunteer subjects walked on a treadmill at moderate rates that they controlled. They were instructed to walk as far as possible without using oxygen at a rate higher than the SCSR could produce. Distances walked ranged from 2.1 km to 9.2 km with an average distance of 6.0 km. SCSR operating times ranged from 30 min to 94 min. If the required walking distance is farther than this, multiple units will have to be available to allow safe escape.

Adult↗

PubMed2006

Maximum static inspiratory and expiratory pressures with different lung volumes.

BACKGROUND: Maximum pressures developed by the respiratory muscles can indicate the health of the respiratory system, help to determine maximum respiratory flow rates, and contribute to respiratory power development. Past measurements of maximum pressures have been found to be inadequate for inclusion in some exercise models involving respiration. METHODS: Maximum inspiratory and expiratory airway pressures were measured over a range of lung volumes in 29 female and 19 male adults. A commercial bell spirometry system was programmed to occlude airflow at nine target lung volumes ranging from 10% to 90% of vital capacity. RESULTS: In women, maximum expiratory pressure increased with volume from 39 to 61 cmH2O and maximum inspiratory pressure decreased with volume from 66 to 28 cmH2O. In men, maximum expiratory pressure increased with volume from 63 to 97 cmH2O and maximum inspiratory pressure decreased with volume from 97 to 39 cmH2O. Equations describing pressures for both sexes are: Pe/Pmax = 0.1426 Ln( %VC) + 0.3402 R2 = 0.95 Pi/Pmax = 0.234 Ln(100 - %VC) - 0.0828 R2 = 0.96 CONCLUSION: These results were found to be consistent with values and trends obtained by other authors. Regression equations may be suitable for respiratory mechanics models.

Adult↗

PubMed2006

The correlation between personality type and performance time while wearing a respirator.

Many studies have shown that individuals perform better if not wearing a respirator compared with wearing a respirator. This study examined the degree of performance reduction attributable to specific dominant character traits. The subjects performed on a treadmill at a constant speed and grade resulting in 80-85% VO(2)max. A modified M40 respirator was used to create three levels of inspiratory resistance: 2.8, 16.8, and 27.3 cmH(2)O*(sec/L). The 31 subjects were tested using a Myers-Briggs Type Indicator and State-Trait Anxiety Inventory. Multiple regressions and an ANOVA were used to test for correlation. When air intake is very constricted, the only multiple regression equation that was found to be statistically significant was sensing-intuition (how one takes in information) and thinking-feeling (how one makes a decision) vs. performance time for the highest value of inhalation resistance. A simple linear regression between trait anxiety level and performance time was not found to be statistically significant for the same highest value of inhalation resistance.

Adult↗

PubMed2005

Exercise performance while wearing a tight-fitting powered air purifying respirator with limited flow.

Sixteen subjects exercised at 80-85% of maximal aerobic capacity on a treadmill while wearing a tight-fitting, FRM40-Turbo Powered Air Purifying Respirator (PAPR). The PAPR was powered by a DC power supply to give flow rates of 0%, 30%, 66%, 94%, and 100% of rated maximum blower capacity of 110 L/min. As flow rate was reduced, so was performance time. There was a 20% reduction in performance time as blower flow changed from 100% to 0% of maximum. Significant differences in breathing apparatus comfort and facial thermal comfort were found as flow rate varied. It was concluded that inadequate blower flow rate decreases performance time, facial cooling, and respirator comfort.

Adolescent↗

PubMed2005

Exercise-induced respiratory resistance changes as measured with the airflow perturbation device.

Respiratory resistance (Rrs) changes during physical labor can modify the work of breathing and thus influence the time that the labor can be performed. Ideal in vivo human respiratory performance measurements should have fine temporal resolution and minimally impact the respiratory system itself. The airflow perturbation device (APD) provides respiratory resistance measurements in this manner. Pre-exercise Rrs was compared with post-exercise Rrs, continuously monitored for 6 min in 12 non-asthmatic subjects. Rrs following exercise at 70-75% VO2max was below pre-exercise levels for 40 s into recovery (p < 0.05) and inhalation resistance differed more markedly than exhalation resistance. The same post-exercise Rrs decline was found when Rrs measurements were compared to those taken during flow rates comparable to those found late in recovery. Results indicate that (1) Rrs indeed declines following exercise in non-asthmatic subjects, probably due to bronchial dilation, (2) Rrs changes can occur on short time scales, (3) Rrs changes are not related primarily to flow rate.

Adolescent↗

PubMed2004

Decrease of resistance to air flow with nasal strips as measured with the airflow perturbation device.

BACKGROUND: Nasal strips are used by athletes, people who snore, and asthmatics to ease the burden of breathing. Although there are some published studies that demonstrate higher flow with nasal strips, none had directly measured the effect of the strips on nasal resistance using the airflow perturbation device (APD). The APD is an inexpensive instrument that can measure respiratory resistance based on changes in mouth pressure and rate of airflow. METHOD: This study tested forty-seven volunteers (14 men and 33 women), ranging in age from 17 to 51. Each volunteer was instructed to breathe normally into the APD using an oronasal mask with and without nasal strips. The APD measured respiratory resistance during inhalation, exhalation, and an average of the two. RESULTS: Results of a paired mean t-test comparing nasal strip against no nasal strip were statistically significant at the p = 0.05 level. The Breathe Right nasal dilator strips lowered nasal resistance by an average of 0.5 cm H20/Lps from an average nasal resistance of 5.5 cm H20/Lps. CONCLUSIONS: Nasal strips reduce nasal resistance when measured with the APD. The effect is equal during exhalation and during inhalation.

Adolescent↗

PubMed2004

Effect of differing facial characteristics on breathing resistance inside a respirator mask.

A group of subjects with a large range of facial characteristics was asked to breathe deeply while wearing a full facepiece respirator. The facial characteristics noted were head length, head depth, bizygomatic breadth, lip length, and Menton-Sellion length. External resistances to inhalation or exhalation were varied in each of the trials. The data collected were analyzed for possible correlation between facial characteristics and breathing resistance. Although respirator resistances were found to vary, no statistically significant correlation was found with anthropometric measurements.

Adolescent↗

PubMed2004

Validation of airflow perturbation device resistance measurements in excised sheep lungs.

The airflow perturbation device (APD) is a recently redesigned instrument to measure resistance in the respiratory system. The APD is small and easy to use, gives rapid resistance measurements, and can easily separate inhalation from exhalation components. It also possesses some operational characteristics similar to forced oscillation (FO). Excised sheep lungs within a respiratory chamber were used to determine the effective resistance domain of the APD. Retrograde catheters were installed in the airways, alveolar capsules were used to measure alveolar pressures, and chamber pressure was used as pleural pressure. FO measurements were made to compare with the APD. The APD was found to give a resistance measurement about 1.7 to 1.9 times airway resistance. FO gave a resistance measurement 1.4 times airway resistance. Resistance values differed depending on analysis procedure and frequency of oscillation. Both devices were found to produce oscillations beyond the pleural surface of the lungs. It was concluded that the APD and FO measure similar respiratory resistances.

Airway Resistance↗

PubMed2002

Oxygen consumption, heat production, and muscular efficiency during uphill and downhill walking.

Oxygen consumption, heat production, and muscular efficiency for walking are parameters important to know for ergonomics models and equipment design. Most of these assume that the oxygen consumption and heat production of downhill walking are the same as for uphill walking. Eight subjects wearing insulating clothing walked on a treadmill at three uphill and three downhill grades, and at level grade at a rate of 1.1 m/s. Oxygen consumption VO2 was calculated from steady state measurements of respiratory minute volume and oxygen percentage. Heat production (q) was calculated from the rate of heat storage in the body and clothing. Least-squares best fit equations for oxygen consumption and heat production found were to be VO2 = 0.813 + 0.0361G + 0.000810G2 - 0.0000302G3 and q = 6.55 + 0.185G + 0.0114G2 - 0.000190G3 where G is percent grade. Approximations show that VO2 (downhill) = 0.5 VO2 (uphill), q (downhill) = 0.67 q (uphill), and muscular efficiency eta (downhill) = -2eta (uphill).

Adolescent↗

PubMed2002

Effects of caffeine on performance of low intensity tasks.

31 college age men and women who consume less than three caffeinated beverages per week agreed to participate as subjects in research on the effects of acute caffeine intake on low intensity task performance. All subjects performed two randomly administered test conditions: (1) caffeine (5 mg/kg) and (2) placebo on separate visits following an initial 1-hr. orientation visit. Subjects were administered the beverage 30 min. prior to performing 12 separate tests assessing basic mathematics, simple response, logical reasoning, hand-eye coordination, and spatial and assembly skills. The Spielberger State Anxiety test was administered immediately after consuming the test beverage and once again at posttest. Analysis showed that caffeine did not significantly affect performance on all tests with the exception of the peripheral awareness (hand-eye coordination) test on which performance was higher after ingesting caffeine. The placebo treatment produced no effect on state anxiety, which contrasted with a significant rise in anxiety after caffeine consumption. State anxiety values were significantly greater after caffeine treatment relative to the placebo at pretest, and this difference persisted at posttest. These results demonstrated that the dose of caffeine increased scores on state anxiety for individuals who consumed less than three caffeinated beverages weekly but had very little effect on performance of low intensity tasks, except for a hand-eye coordination test involving peripheral awareness. Perhaps longer continuous performance of more demanding tasks would be more sensitive.

Adult↗

PubMedDate not supplied

Change is necessary in a biological engineering curriculum.

Success of a Biological Engineering undergraduate educational program can be measured in a number of ways, but however it is measured, a presently successful program can translate into an unsuccessful program if it cannot adjust to different conditions posed by technical advances, student characteristics, and academic pressures. Described in this paper is a Biological Engineering curriculum that has changed significantly since its transformation from Agricultural Engineering in 1993. As a result, student numbers have continued to climb, specific objectives have emerged, and unique courses have been developed. The Biological Resources Engineering program has evolved into a program that emphasizes breadth, fundamentals, communications skills, diversity, and practical engineering judgment.

Curriculum↗