Faculty Bibliography

Two groups of 24 subjects each attempted to discriminate between large elastic and resistive loads during 50 randomized presentations of each load. Breathers inspired from the loads through a J valve, whereas pullers reciprocally stroked the plunger of a 2-liter syringe connected to the J valve. A range of load durations was obtained in each subject by prematurely unloading approximately one-half of the trials at graded times from their onset. Breathers produced random discrimination scores [50.8 +/- 2.5% (SE) correct] when loaded inspirations were shorter than unloaded inspirations [trials in which both loads induced equal airway pressure (and probably respiratory muscle tension) waveforms] and nonrandom discrimination scores (65.7 +/- 2.8% correct) when loaded inspirations were longer than unloaded inspirations (trials in which both loads induced different waveforms). In contrast, pullers produced nonrandom discrimination scores (62.2 +/- 2.9% correct) when loaded airflow durations were shorter than unloaded inspirations [trials in which both loads induced equal line pressure (and therefore limb muscle tension) waveforms]. Supplemental audio feedback related to instantaneous airflow (an expression of movement) improved load perception in breathers (to 64.2 +/- 3.0% correct; P < 0.01), indicating that airflow feedback introduced load-specific information that was lacking during breathing but redundant during pulling. In support of this hypothesis, airflow feedback by itself enabled a third group of listeners to identify load type with equal accuracy as pullers but with greater accuracy than breathers. These findings suggest that 1) uniformed subjects rely heavily on feedback from airway pressure and/or muscle tension receptors to perceive added loads to breathing and 2) limb mechanoreceptors provide a more sensitive appreciation of movement than do respiratory mechanoreceptors

Exercise-induced bronchospasm (EIB) is often inferred from the reduction after exercise in one arbitrarily selected value derived from the maximum expiratory flow-volume (MEFV) curve (eg, FEV1) on a single test; however, patients with symptoms of EIB not meeting these criteria may risk being undiagnosed. To assess the ability of repeated tests using additional MEFV parameters in identifying EIB-prone patients, we investigated the effects of exercise provocation on the MEFV curve on two separate occasions. Of 95 patients with symptoms of EIB, 61 had reproducible exercise-induced changes (< 10 percent intraresponse variation), falling into four patterns: 27 (44 percent) had significantly reduced VC and airflow throughout the MEFV curve; 18 (30 percent) had unchanged VC but decreased airflow throughout the curve; 11 (18 percent) had reduced airflow above 50 percent VC but not below 50 percent VC; and 5 (8 percent) had significant reductions in airflow only at 50 percent VC or below. Of the other 34 subjects, 18 had no apparent response, and 16 responded on only one occasion, making objective assessment of these patients' EIB equivocal. We conclude that for a given individual, failure to meet arbitrary criteria does not rule out EIB. Additionally, a more subjective approach that integrates, among other factors, all routine MEFV curve parameters taken from multiple tests with clinical symptoms and history provide a more accurate assessment of EIB

Strength training of neck muscles, a potentially important approach to injury prevention and rehabilitation, has been limited by the lack of a convenient means of instituting progressive resistance exercise (PRE) programs. By positioning a compressible ball coupled with an air pressure gauge between the head and a wall, eight men, ranging in age from 21 to 46 years, initially measured the maximum voluntary pressure (MVP) generated within the ball (a measure of neck muscle force), while maximally flexing, extending, and laterally flexing their head into the ball. In accordance with PRE principles, they then performed three sets of 10 repetitions of each motion while maintaining ball pressure at 60-80% of the measured MVP. This training program, consisting of three to five sessions per week for 4-7 weeks: 1) increased the MVPs for flexion [to 156 +/- 9% (SE) pretraining, p < 0.05], extension [to 162 +/- 11% (SE) pretraining, p < 0.05], and lateral flexion [to 173 +/- 12% (SE) pretraining, p < 0.05]; and 2) decreased the disparity between the MVPs for left and right lateral flexion, indicating that the weaker side showed greater improvement than the stronger side (p < 0.05). These findings demonstrate that progressive resistance neck exercises, facilitated by a compressible ball coupled with an air pressure gauge, can markedly increase neck muscle strength and decrease lateral force imbalance. J Orthop Sports Phys Ther 1992;16(6):275-280.

Since Maimonides, it has been common in folk medicine to proscribe milk for asthmatics because its putative stimulation of mucus production can exacerbate asthma symptoms. A literature review, however, failed to reveal any data supporting this notion. We, therefore, compared the effects of ingesting 16 oz. of whole milk (16 g lipid), skim milk (2 g lipid), and water (each on a separate day) on: (1) forced expiratory volume in 1 second (FEV1), (2) forced expiratory flow at 50% of vital capacity (V50), and (3) pulmonary diffusing capacity (DLCO) in 11 asthmatic and 10 nonasthmatic subjects. Measurements were taken at 30 minute intervals for 3 hours. The two milk types did not significantly change FEV1 or V50 in either group, indicating that the amount ingested did not change airway resistance sufficiently to alter airflow parameters. In the asthmatic group, however, DLCO decreased progressively over the 3 hours by 6.8 +/- 1.4% (mean +/- SE) per hour after whole milk (maximum reduction = 21 +/- 1.4%) but not after water or skim milk. In the nonasthmatic group, no significant effects were observed on DLCO after any of the liquids. These data suggest that milk lipids can disturb gas exchange in asthmatic patients

The postoperative courses of 39 patients with severe lung disease (31 with obstructive disease and 8 restrictive) who underwent a cardiac operation were retrospectively reviewed. The stay in the intensive care unit of the study group was 7.9 +/- 10.3 days (mean +/- standard deviation) compared with 2.4 +/- 3.9 days for the control group (100 patients with less impaired pulmonary function) (p less than 0.001). The study group also had a greater number of valve replacements than did the control group (p less than 0.01). Patients with obstructive disease had more respiratory complications than did patients with restrictive disease (p less than 0.05). There were 21 cases of atelectasis. Effusions were noted in 11 patients. Ten patients had bronchospasm. Bronchial secretions were a major problem in 6 patients. Pneumonia developed in 4 patients, and pneumothorax occurred in 3 others. The two in-hospital deaths were not directly related to pulmonary complications. Our findings indicate that (1) patients with severe lung impairment generally do well after a cardiac operation but have more postoperative pulmonary complications than patients with less impairment; (2) patients with restrictive pulmonary disease appear to fare better than those with obstructive disease; (3) pulmonary function tests can alert the clinician to the possible risk of postoperative complications, but they cannot, by themselves, be used to exclude patients from operation; and (4) patients with severe pulmonary impairment facing valve replacement are at greater risk of pulmonary complications than patients having other types of cardiac surgical intervention

Pentoxifylline is a xanthine derivative with hemorrheologic and vascular properties that may improve gas exchange in patients with chronic obstructive pulmonary disease (COPD). We tested this hypothesis in 12 patients with COPD (mean FEV1 = 40 percent predicted; mean DCO, 8.6 ml/min/mm Hg) randomly divided into a treatment and control group and six healthy volunteers. Following establishment of baseline DCO and maximum expiratory flow volume (MEFV) curve values, each subject in the treatment and healthy groups took 400 mg of pentoxifylline three times a day for 12 weeks. Weekly DCO and MEFV curves were measured before treadmill exercise in both COPD groups and before and after exercise in the healthy group. The MEFV curve parameters from the final three weeks of therapy did not differ significantly from baseline values. During this time, however, the treatment COPD group's resting DCO rose by 8.2 +/- 2.4 percent over baseline level (p less than 0.01). Treadmill walk time increased from 17.7 +/- 2.9 minutes to 23.2 +/- 2.9 minutes (p less than 0.02). This was accompanied by improved exercise oxygen saturation measured by oximetry (SoxiO2). Premedication SoxiO2 fell from 92.8 +/- 1.2 percent to 88.6 +/- 2.5 percent during exercise, and from 94.4 +/- 1.1 percent to only 91.8 +/- 1.0 percent after 12 weeks of medication (p less than 0.05). No such improvement was noted in the control COPD group. Although the healthy group's resting SoxiO2 and DCO did not change during treatment, their exercise DCO increased significantly from 36.3 +/- 3.1 ml/min/mm Hg to 41.8 +/- 3.5 ml/min/mm Hg (p less than 0.001). These data demonstrate that pentoxifylline improves gas exchange, possibly by increasing cardiac output, and/or by raising mixed venous PO2, and/or by improving blood flow to underperfused alveoli

We present the case of a young woman with a right aortic arch who first became symptomatic when she began a vigorous exercise program. Her symptoms were very suggestive of exercise-induced bronchospasm. Her flow-volume curves, however, showed evidence of variable intrathoracic large airways obstruction. A magnetic resonance imaging scan confirmed the presence of severe tracheal narrowing caused by her right aortic arch

Eleven people with spinal cord injury (SCI) (C4-T6) participated in a program of functional electric stimulation (FES) of their paralyzed leg muscles using the REGYS I system. Individualized protocols consisted of an initial phase of weight lifting, an intermediate phase of ergometer pedalling against 0 Kilopond (kp) alternated with 1/8kp for six two-minute runs separated by two-minute rest periods, and a final phase of 36 sessions of continuous ergometer pedalling against variable resistance. A metabolic analyzer measured exercise stress test parameters before and after each phase while subjects pedalled against incremented resistance. Peak oxygen consumption and total stress test time increased markedly. The respiratory exchange ratio (R=VCO2/VO2) at termination, however, did not differ from unity at any phase, indicating that fatigue (defined as a failure to maintain a pedalling frequency of 35 rpm) occurred when the anaerobic threshold was reached, and that FES exercise can increase the aerobic capacity of persons with SCI. The initial velocity of quadriceps shortening (derived from patellar tendon displacements) also decreased in five of eight subjects tested, suggesting corresponding increases in quadriceps twitch time. Since muscle inactivity converts slow-twitch to fast-twitch fibers, our subjects' increased muscle endurance accompanied by decreased muscle-shortening velocity were compatible with a disproportionate increase in the function of slow-twitch fibers relative to fast-twitch fibers. Although these findings demonstrate that lower extremity FES exercises can safely achieve significant aerobic training effects in patients with SCI, the peak levels of cardiorespiratory performance were similar to those reported for quadriplegic people performing maximal voluntary upper extremity exercises