Biomedical subjects

C R Dooly

Publications and source records attributed to C R Dooly.

9 recordsLinked to original sources

PubMed1998

Generating the Snellen Chart by computer.

The Snellen Chart is the eye chart that is commonly used to measure visual acuity. The chart has combinations of nine different letters in eleven different lines, each smaller than the one above. Repeated measures of visual acuity may result in chart memorization and false information. Thus, a computer program was written to produce randomized multiple versions of Snellen eye charts. The chart may be changed at some distance from the computer in order to hear subject letter identifications during exercise testing. Different sized letters can also be produced so that the distance from the subject to the chart can vary.

Humans↗

PubMed1998

Respirator performance ratings for speech intelligibility.

A respirator degrades speech intelligibility and thus interferes with the ability of the wearer to communicate. The magnitude of this degradation is not well-studied and can vary as a function of numerous parameters. This study investigated the performance degradation of speech intelligibility in low-level noise for different speaker-listener distances and message sets (single words or predictable sentences) that occurred while wearing a respirator compared with not wearing a respirator. Thirteen speaker-listener pairs with normal hearing and speech were used. Speaker-listener separation distances were 0.61, 1.22, 1.83, 2.44, 3.05, and 3.66 m (2, 4, 6, 8, 10, and 12 ft) for the respirator condition and 1.22, 2.44, 3.05, 6.1, 9.15, and 12.2 m (4, 8, 10, 20, 30, and 40 ft) for the no-respirator condition. The means of the scores were used to determine the speech performance rating for both the single-word and sentence comprehension tests. The performance rating expresses the percentage of performance that can be expected while wearing a respirator compared with not wearing a respirator. Scores were interpolated linearly at distances at which no data were obtained. As expected, the speech performance rating was higher for the sentence comprehension test than for the single-word comprehension test at each distance. At a distance of 12.2 m, the speech performance rating for the sentence comprehension was 70%. For the single-word comprehension test, the speech performance rating was zero for distances greater than 9.1 m.

Adolescent↗

PubMed1997

Sweat rate inside a full-facepiece respirator.

The accumulation of sweat inside a full-facepiece respirator mask and the rise in facial skin temperature can be important factors for acceptability of respirators worn in the heat. This study questioned how much sweat would have to be removed from a respirator (if a design to remove accumulated sweat were possible). Results from 20 subjects sitting in a warm, humid environment (35 degrees C and 90% relative humidity) for 90 minutes indicated that the average value was about 0.203 g sweat/min from the face, head, and neck, with most of that coming from the neck region. Men were found to have higher sweating rates than women. The results indicate that a large amount of sweat could accumulate inside the mask over a typical 8-hour day. Average facial skin temperature was found to rise about 2 degrees C over the 90-minutes test, and this rise could likely be the cause of the very uncomfortable rating given to the respirator.

Equipment Design↗

PubMed1997

Effect of altered vision on constant load exercise performance while wearing a respirator.

Previous testing has shown that visual acuity greatly influences task performance at light work rate levels. At moderate to heavy work rates, however, the Performance Rating Table (PRT) predicts almost no visual acuity effect. This experiment was performed to determine if the PRT value is realistic. Ten subjects walked on a treadmill at 75-80% of their maximum heart rates until their voluntary end points. Subjects wore various masks of the same kind, each with a different set of clouded lenses. Visual acuities, as measured on the Snellen eye chart, were measured before, during, and after exercise. It was found that visual acuity did not influence performance time, and that an average value for a performance rating of 91 must have been influenced by other mask factors besides visual acuity. These other factors are most likely respiratory stress, thermal stress, and other vision elements. The full-facepiece masks used in this study adversely affected visual acuity by about three-quarters of a Snellen line during exercise. Postexercise visual acuities were found to first decrease below pre-exercise values, then become better than pre-exercise values, then decline asymptotically to pre-exercise values.

Adult↗

PubMed1996

Peak oxygen consumption and lactate threshold in full mask versus mouth mask conditions during incremental exercise.

Respirator masks vary in inhalation and exhalation resistance, and in dead volume. It is believed that these factors may contribute significantly to an early anaerobic threshold in mask wearers during maximal exercise. Very little is known concerning the effect of respirator masks on maximal oxygen consumption (VO2max) and the lactate threshold (LT). The purpose of the present study was to assess peak VO2 (VO2peak), LT and the ventilatory threshold (VT) of 14 experienced cyclists performing two maximal cycle exercise protocols while wearing a full respirator mask (FM) (M17 type) and a mouth mask (MM). VO2peak was 10% lower under FM conditions. Peak values for ventilation (VEpeak), respiratory rate (fbpeak) and tidal volume (VTpeak) were all significantly lower under with FM versus MM conditions. Performance time and maximal heart rate (fcpeak) were not different between mask conditions. The LT and VT when expressed in %VO2peak, and the lactate concentration (mmol.l-1) at LT and VT were not significantly different across mask conditions. Bland-Altman plots demonstrated longer inhalation times, decreased Fr values and greater oxygen extraction under FM conditions. Thus, perhaps due to the increased inhalation resistance of the FM condition, subjects were unable to attain their "normal" VO2 despite similar performance times and maximal fc. Furthermore, despite a diminished VO2peak with FM, LT and VT appeared to be the same as with a MM.

Adolescent↗

PubMed1995

Influence of anxiety level on work performance with and without a respirator mask.

Work performance of mask wearers has been shown to be less than performance of the same individuals without masks. How much this performance decrement is attributable to psychological factors was the subject of this study. This experiment was designed to give quantitative information about the effect of anxiety level on relative work performance while wearing a respirator mask. Twenty subjects were tested for trait anxiety levels and performed on a treadmill at 80-85% of their maximum heart rates until they reached voluntary end-point. Physiological, metabolic, and subjective measurements were taken every minute. While experimental variability precluded many of the results from achieving statistical significance, performance times with the mask averaged less than without the mask. Anxious subjects experience more discomfort, perform for shorter times, and accomplish less total work than their lower anxiety counterparts, even when rate of work can be adjusted.

Adult↗

PubMed1995

Respirator mask effects on exercise metabolic measures.

To test effects of respirator masks on maximum oxygen uptake, ventilation threshold, and lactate threshold, 14 subjects underwent incremental bicycle exercise with and without masks. There was a statistically significant difference in final oxygen consumption between the two conditions, but other results suggest that the physiological measure of maximum oxygen uptake was not reached at termination for the full-mask condition. Lactate and ventilation thresholds were not affected by mask condition. Hypoventilation while wearing masks caused higher amounts of blood lactate accumulation. The resulting higher mask CO2 levels and lower O2 levels, normally attributed to mask dead volume, may instead be due to mask resistance.

Adult↗

PubMed1994

System to obtain exercise respiratory flow waveforms.

A system for obtaining respiratory flow rate waveforms, tidal volume, minute volume, respiration rate, inhalation time and exhalation time is described. The system is based on a microcomputer with analog-to-digital converter board. System software allows calibration, data acquisition and data analysis. Data can be obtained automatically at fixed time intervals. The system is inexpensive and reliable.

Analog-Digital Conversion↗

PubMed1994

Task performance with visual acuity while wearing a respiratory mask.

Forty-six subjects were required to perform a console-monitoring and two hand-eye coordination tasks while wearing masks with lenses clouded to give seven levels of visual acuity. The console-monitoring task performance was found to be the most sensitive to visual acuity, followed by the random hand-eye coordination task. These results can be used to help predict performance degradation when lenses become clouded due to condensation or particulate deposition.

Adolescent↗