Arm training reduces the VO2 and VE cost of unsupported arm exercise and elevation in chronic obstructive pulmonary disease

BACKGROUND

Patients with severe chronic obstructive pulmonary disease (COPD) may develop dyspnea with minimal arm activity, thoracoabdominal dyssynchrony with unsupported arm exercise (UAEX) and increased oxygen uptake (VO2), and minute ventilation (VE) with simple unsupported arm elevation (UAE) and UAEX. We investigated whether unsupported arm training, as the only form of exercise, could decrease the VO2 and VE cost (percentage increase from resting baseline) associated with unsupported arm elevation and exercise, respectively.

METHODS

Twenty-six patients with severe COPD were randomized to 21-24 sessions of unsupported arm (ARMT) or low-intensity resistive breathing (RBT) training as the only form of exercise. Patients were studied before and after training using a metabolic cart and esophageal and gastric pressures to evaluate metabolic and respiratory muscle function.

RESULTS

After ARMT, the VO2 (58% vs 38% increase, P < 0.05) and VE (41% v. 21% increase, P < 0.05) cost for UAEX at exercise isotime decreased and endurance time increased. Similarly the VO2 (25% vs 18% increase, P < 0.05) cost decreased and VE no longer increased in response to 2 minutes of UAE after ARMT. The RBT group showed no such change. No improvement in ventilatory load or respiratory muscle function could be identified to explain the physiologic changes observed. After ARMT, mean inspiratory flow (VT/TL), a measure of central respiratory drive, was reduced during UAEX and the expected increase during UAE did not occur.

CONCLUSION

We conclude that arm training reduces the VO2 and VE cost of UAE and UAEX, possibly through improved synchronization and coordination of accessory muscle action during unsupported arm activity.

Pulmonary rehabilitation improves exercise capacity in older elderly patients with COPD

Pulmonary rehabilitation has been shown to improve exercise capacity in patients with COPD. It has been suggested that this improvement applies to all age groups; however, to our knowledge, the effects of pulmonary rehabilitation on older elderly patients (> or = 75 years of age) have not been studied. We compared changes in 12-min walking distance (12MD) and self-assessment scores in 47 older elderly patients with moderate to severe COPD who completed inpatient or outpatient pulmonary rehabilitation with those achieved by 87 younger patients who participated in the same programs from 1987 to 1992. There were 28 older elderly individuals (mean +/- SEM, 78 +/- 1 years) in the outpatient group and 56 younger patients (64 +/- 1 years). There were no differences between older and younger outpatients with respect to FEV1, FEV1/FVC, maximum inspiratory pressure (PImax), baseline 12MD, or baseline self-assessment score. After outpatient pulmonary rehabilitation, 12MD and self-assessment scores improved significantly in both groups. Inpatients included 19 older elderly individuals (81 +/- 1 years) who were also similar to the 31 younger inpatients (64 +/- 1 years) in FEV1, FEV1/FVC, PImax, and baseline self-assessment score, but they tended to be more limited in terms of baseline 12MD (p = 0.09). After inpatient pulmonary rehabilitation, significant improvements in 12MD and self-assessment were seen in both groups. We conclude that comprehensive outpatient and inpatient pulmonary rehabilitation programs are as beneficial in older elderly patients with COPD as they are in younger patients with similar lung function abnormalities. Patients 75 years of age or older should be considered for comprehensive pulmonary rehabilitation.

Hypersensitivity pneumonitis from residential composting: residential composter's lung

Hypersensitivity pneumonitis results when a susceptible individual is exposed to sufficient airborne material capable of inducing a systemic and pulmonary immune response. We describe a man who had all the classic manifestations of hypersensitivity pneumonitis but in whom the circumstances of sensitization, residential yard work with composted yard clippings, has not previously been reported. We call this new entity residential composter's lung.

Tuberculosis. An epidemic in older adults

The incidence of tuberculosis is disproportionately high in our elderly population. This group appears to be at high risk because many were infected early in life. Additional factors contributing to increased risk in the elderly probably include low clinical suspicion for tuberculosis in this age group, unusual or nonspecific clinical and roentgenographic presentations, difficulties in interpreting the tuberculin skin test, and the presence of associated illnesses that may lead to delay in diagnosis. Failure to diagnose tuberculosis in this population has important public health implications, particularly in nursing homes and long-term care facilities. Tuberculosis is usually easily diagnosed when suspected in elderly patients, and effective therapy is available for prevention and treatment of this disease. The special needs of old patients must be considered when these regimens are applied. Increased awareness of tuberculosis in the elderly is important for the success of strategies that have been developed to eliminate tuberculosis from the United States. As our population continues to age, physicians who treat the elderly must be vigilant in suspecting tuberculosis as a cause of illness in these patients.

Eosinophilic pleuritis due to propylthiouracil

We report a patient who developed eosinophilic pleuritis due to propylthiouracil. Although immunologic side effects associated with thionamides previously have been described, this is the first reported case of an isolated eosinophilic pleural reaction.

Pulmonary rehabilitation that includes arm exercise reduces metabolic and ventilatory requirements for simple arm elevation

Simple arm elevation results in increased metabolic and ventilatory requirements in patients with chronic airflow obstruction (CAO). These demands contribute to the dyspnea that is frequently reported when these patients perform activities of daily living involving the arms. We hypothesized that a comprehensive pulmonary rehabilitation (PR) program that includes upper extremity training would lower the ventilatory requirement for arm elevation. Metabolic and ventilatory responses to 2 min of simple arm elevation were studied in 14 patients with CAO before and after PR. Respiratory muscle strength was determined in 11 patients by measurement of maximal transdiaphragmatic pressure (Pdimax). Oxygen uptake (VO2), carbon dioxide production (VCO2), heart rate (HR), minute ventilation (VE), tidal volume (VT), and respiratory rate were measured at rest with the arms down and during 2 min of arm elevation. Before PR, arm elevation led to significant increases in VO2, VCO2, HR, and VE. After PR, pulmonary function, Pdimax, and resting metabolic and ventilatory parameters with the arms down were unchanged; however, during arm elevation, VO2, VCO2, and VE were significantly less than they were before PR. We conclude that a comprehensive PR program that includes upper extremity exercises leads to a reduction in the ventilatory requirement for simple arm elevation. This type of program may allow patients with CAO to perform sustained upper extremity activities with less dyspnea.

Respiratory response and ventilatory muscle recruitment during arm elevation in normal subjects

Despite the fact that the arms are used extensively in daily life and that some of the muscles of the shoulder girdle share both a respiratory and a positional function for the arms, surprisingly little is known about the respiratory response to unsupported upper extremity activity. To determine the respiratory consequences of simple arm elevation during tidal breathing, we measured minute ventilation (VE), tidal volume (VT), respiratory rate (f), heart rate (HR), oxygen uptake (VO2), and carbon dioxide production (VCO2) in 22 normal subjects seated with arms elevated in front of them to shoulder level (AE) for 2 min and down at the sides (AD) for the same time period. The sequence was randomized. Compared with AD, during AE there were significant increases in VO2 (336 +/- 18 vs 289 +/- 14 ml/min, p less than 0.001), VCO2 (315 +/- 23 vs 245 +/- 16 ml/min, p less than 0.001), HR (84 +/- 6 vs 73 +/- 4 beats/min, p less than 0.05), VE (11.5 +/- 0.9 vs 9.3 +/- 0.6 L/min, p less than 0.001), and VT (868 +/- 66 vs 721 +/- 48 ml, p less than 0.001). In 11 subjects, breath-by-breath metabolic and ventilatory parameters were studied with AD for 2 min, AE for 2 min, and with AD for 3 min while also recording gastric (Pg), pleural (Ppl), and transdiaphragmatic pressures (Pdi). With AE, there was a significant increase in Pg at end inspiration (PgI, 15.4 +/- 3.2 vs 11.9 +/- 2.7 cm H2O, p less than 0.01) and in Pdi (26.5 +/- 3.4 vs 21.4 +/- 2.4 cm H2O, p less than 0.01) with no change in Pg at end expiration (PgE) or in Ppl. The increases in VO2, VCO2, VE, and VT during arm elevation persisted for 2 min after arm lowering, whereas Pgi and Pdi abruptly dropped as the arms were lowered. We conclude that simple arm elevation during tidal breathing results in significant increases in metabolic and ventilatory requirements. These increased demands are associated with higher PgI and Pdi suggesting an increased diaphragmatic contribution to the generation of ventilatory pressures. The sudden drop in Pg with arm lowering indicate a change in ventilatory muscle and or torso recruitment independent of the metabolic drive and ventilatory needs. These findings may help explain the limitation that has been reported in some normal subjects and in many patients with lung disease during unsupported upper extremity activity.

Respiratory tract infection complicating transtracheal oxygen therapy

Transtracheal oxygen is generally well tolerated in patients with chronic hypoxemia. Minor complications are common, but there are few reports of serious respiratory tract infections associated with transtracheal oxygen therapy. We describe four patients with interstitial lung disease who had frequent lower respiratory tract infections requiring hospitalization after initiation of transtracheal oxygen therapy.

Respiratory response to arm elevation in patients with chronic airflow obstruction

We have shown that patients with chronic airflow obstruction (CAO) complain of disabling dyspnea when performing seemingly trivial tasks with unsupported arms. Surprisingly little is known about the metabolic and ventilatory responses to unsupported upper extremity activity even though some of the muscles of the upper torso and shoulder girdle are used to perform simple and complex everyday tasks as well as partake in ventilation. To determine the effect of simple arm elevation in 20 patients with CAO we studied their lung function, VO2, VCO2, and VE, with arms down at the side (AD), during 2 min with arms extended forward up to shoulder level (AE), and during recovery. To determine the pattern of ventilatory muscle recruitment we also measured endoesophageal (Ppl), gastric (Pg), and transdiaphragmatic (Pdl) pressures. In five of the patients the electromyographic signal (EMG) of the sternocleidomastoid (Sm) muscle was recorded and analyzed in its time domain (amplitude) and power spectrum density (median frequency). Within 30 s of arm elevation VO2, VCO2, and VE rose and remained elevated for 1 min after the arms were lowered. The increase in VE resulted from increases in respiratory rate and minimal rise in tidal volume (VT). With AE, FEV1 decreased by 5% (p less than 0.02) but FRC increased by 2% (p less than 0.05). Peak inspiratory pressure (Pimax) dropped from 54 +/- 4 to 48 +/- 4 cm H2O (p less than 0.005); Pdimax remained unchanged. Immediately after raising the arms Pgi, inspiratory swing in Pdi (delta Pdi), end-expiratory Ppl, and end-expiratory Pg increased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors influencing ventilatory muscle recruitment in patients with chronic airflow obstruction

Patients with chronic airflow obstruction (CAO) frequently develop abnormal thoraco-abdominal excursion, but the patterns described are inconsistent and the factors that relate to their development remain unknown. We studied 45 stable patients with FEV1 ranging from 0.36 to 2.1 L. A pattern of ventilatory muscle recruitment (VMR) was established by simultaneously measuring gastric (Pg) and pleural (Ppl) pressures and rib cage (Vrc) and abdominal (Vab) volume displacement with inductance plethysmography. From these tracings, Pg-Ppl plots were constructed and the delta Pg/delta Ppl values were calculated. The delta Pg/delta Ppl was validated in 15 patients with simultaneous analysis of Vab-Pg plots. Pearson's test and multiple regression analyses were used to correlate delta Pg/delta Ppl to factors thought to influence respiratory muscle function such as age, sex, nutritional status (weight/height, albumin), hyperinflation, airflow obstruction, and arterial blood gases. We found a direct correlation between a more positive delta Pg/delta Ppl value and increasing hyperinflation (r = 0.69, p less than 0.0001), increasing airflow obstruction (r = -0.55, p less than 0.001), and decreasing diaphragmatic strength (r2 = 0.32, p less than 0.001). We also found that expiratory Ppl became more positive with decreasing FEV1 (r2 = 0.33, p less than 0.001). This change in VMR was independent of age, sex, nutritional status, and arterial blood gas determinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory muscle fatigue from functional upper airway obstruction

A case of functional upper airway obstruction is presented. The case is unusual because even though no identifiable organic cause could be found for dyspnea and stridor, the patient developed respiratory failure from respiratory muscle fatigue.

Transtracheal oxygen decreases inspired minute ventilation

Although patients using transtracheal oxygen (TTO2) frequently report decreased dyspnea and improved exercise tolerance, the mechanism for these effects is unknown. We hypothesized that these patients might have decreased inspired minute ventilation (VI), and this might be one mechanism for their decreased dyspnea and improved exercise tolerance. The effects of TTO2 on VI were studied in seven patients with chronic hypoxemia; two had chronic obstructive lung disease and five had severe restrictive disorders. VI, exhaled minute ventilation (VE), respiratory rate (RR), tidal volume (VT), earlobe O2 saturation (O2 sat), and arterial blood gases were measured while patients received varying amounts of oxygen either transtracheally or by mouth to achieve equivalent degrees of oxygenation. With TTO2 VI was reduced compared to VI with mouth O2 at similar levels of PaO2. As TTO2 flow rate increased, VI decreased; at 6 L/min O2 delivered transtracheally, mean VI was reduced by 54 +/- 7.0%. Reduction in VI was due to decreased VT; RR did not change. To determine if air delivered transtracheally decreased VI, five patients were studied while receiving air transtracheally or by mouth. With transtracheal air, VI was significantly less than VI obtained while breathing air by mouth. We conclude that VI is decreased when oxygen or air is delivered directly into the trachea and that VI decreases as transtracheal flow increases. This effect is not due solely to changes in oxygenation. Decreased dyspnea and improved exercise tolerance in patients using TTO2 may be due to decreased VI and decreased inspiratory work of breathing.