The validity of the Computer Face Scale for measuring pediatric pain and mood.

OBJECTIVE: The aim was to assess the validity of the Computer Face Scale. METHODS: Forty children (5-13 years old) rated pain and mood prior to and twice following tonsillectomy. The children used the Computer Face Scale to adjust a cartoon face to rate pain and mood. During sessions one and two, the children also chose an expression on the Wong-Baker Faces Scale to rate their pain, and they reported their mood verbally on a seven-point scale. RESULTS: On average, the children reported no pain and a positive mood prior to surgery. Soon after surgery, they reported mild pain and a slightly negative mood. An hour later, they reported decreases in pain and return to a positive mood. The differences between presurgery and postsurgery ratings were statistically significant (P ≤ 0.001) for all measures. The correlation between the two mood measures was 0.88 before surgery and 0.78 afterward. The correlation between the two measures of pain was 0.83 after surgery (P's < 0.001). CONCLUSIONS: The results support the validity of the Computer Face Scale. The mean ratings of pain and mood followed the expected pattern from pre- to postsurgery, and there was a significant association between ratings obtained by different methods. The Computer Face Scale provides a simple-to-use scale with more resolution and electronic capture, which may provide advantages in numerous clinical and research applications.

Longitudinal changes in patient-reported dyspnea in patients with COPD.

BACKGROUND: Although guidelines recommend monitoring symptoms in patients with chronic obstructive pulmonary disease (COPD), there is limited information on the longitudinal changes in patient-reported dyspnea (PRD) related to activities of daily living. The hypothesis was that PRD scores on the modified Medical Research Council (mMRC) scale, the self-administered computerized (SAC) transition dyspnea index (TDI), and the University of California San Diego Shortness of Breath questionnaire (UCSD SOBQ) would demonstrate progression over two years. METHODS: Observational cohort study of symptomatic patients with stable COPD evaluated every 6 months for 2 years. Patients rated the impact of activities of daily living on dyspnea using three patient-reported instruments presented in random order, and then performed post-bronchodilator (pBD) spirometry. RESULTS: Seventy patients (37 female/33 male; age: 66 ± 9 years; and pBD forced expiratory volume in one second [(FEV1): 51 ± 16% predicted] participated. Using fixed effects regression modeling, there was significant worsening in the PRD scores with the SAC TDI (-0.9 ± 2.7; p = 0.03) and UCSD SOBQ (+5.7 ± 18.3; p = 0.001), but not with the mMRC scale (p = 0.52). Both pBD FEV1 (p = 0.19) and pBD forced vital capacity (p = 0.65) were unchanged. CONCLUSIONS: Multidimensional instruments (SAC TDI and UCSD SOBQ) demonstrated the frequently observed decline in PRD experienced by patients with COPD. The progression in PRD occurred despite stable lung function. Monitoring PRD provides unique clinical information and should be considered along with measuring lung function to assess patient status over time.

Reliability of a preliminary 3-D pain mapping program.

OBJECTIVE: The objective of this preliminary investigation was to evaluate the test-retest reliability of a new pain assessment method referred to as 3-D pain mapping. METHODS: In Study 1, 101 chronic noncancer pain patients from four sites reported their pain using the method on two occasions (separated by approximately 10 days). The patients marked intensity, surface location, and depth of pain on a 3-D computer display of a male or female body. The model body could be rotated in order to mark multiple pain locations. In Study 2, 25 patients from a single site were tested with a revised version of the mapping program used in Study 1. Each patient gave ratings on two occasions separated by approximately 1 week. RESULTS: In Study 1, the intra-class correlations of the 3-D pain mapping measures were moderate to high for maximum pain intensity (0.73), vertical location of the point of maximum pain (0.94), and the number of pain marks (0.84). Correlations were low for the horizontal location of the point of maximum pain (0.56) and for the depth of pain (0.50). In Study 2, using the revised program, intra-class correlations were moderate for pain intensity (0.76), and high for the vertical (0.99) and horizontal (0.98) locations of the point of maximum pain, number of pain marks (0.89), and the depth of pain (0.84). CONCLUSION: Three-dimensional pain mapping enables patients to report the location and intensity of their pain on all parts of the body, and such ratings are highly reliable. Future studies are needed to determine whether the clinical value of this method can improve the accuracy of pain diagnoses and the quality of pain management.

Neuromodulatory effect of endogenous opioids on the intensity and unpleasantness of breathlessness during resistive load breathing in COPD.

BACKGROUND: Endogenous opioids are naturally occurring peptides released by the brain in response to noxious stimuli. Although these naturally occurring peptides modulate pain, it is unknown whether endogenous opioids affect the perception of breathlessness associated with a specific respiratory challenge. The hypothesis is that intravenous administration of naloxone, used to block opioid signaling and inhibit neural pathways, will increase ratings of breathlessness during resistive load breathing (RLB) in patients with chronic obstructive pulmonary disease (COPD). METHODS: Fourteen patients with COPD (age, 64 ± 9 years) inspired through resistances during practice sessions to identify an individualized target load that caused ratings of intensity and/or unpleasantness of breathlessness ≥ 50 mm on a 100 mm visual analog scale. At two intervention visits, serum beta-endorphins were measured, naloxone (10 mg/25 ml) or normal saline (25 ml) was administered intravenously, and patients rated the two dimensions of breathlessness each minute during RLB. RESULTS: Patient ratings of intensity (p = 0.0004) and unpleasantness (p = 0.024) of breathlessness were higher with naloxone compared with normal saline. Eleven patients (79%) reported that it was easier to breathe during RLB with normal saline (p = 0.025). RLB led to significant increases in serum beta-endorphin immunoreactivity and decreases in inspiratory capacity. There were no significant differences in physiological responses between interventions. CONCLUSIONS: Endogenous opioids modulate the intensity and the unpleasantness of breathlessness in patients with COPD. Differences in breathlessness ratings between interventions were clinically relevant based on the patients' global assessment.

Quality of chronic pain websites.

BACKGROUND: The Web not only can play a role in helping patients learn about their chronic pain, but can also be a source of misleading or untrue information. This study evaluates the quality of Internet information available concerning chronic pain at different sites, and determines the relation between quality and the source and character of the Websites. METHODS: A survey was conducted of patients seen at the Pain Management Center at Dartmouth-Hitchcock Medical Center (DHMC). Patients with access to the Internet identified the five most common keywords they used to look up information: pain, chronic pain, back pain, arthritis, and fibromyalgia. A focus group of pain clinicians at DHMC then chose the quality criteria to evaluate Websites. The criteria consisted of 16 items in five domains: etiology, diagnosis, goals of treatment, treatment options, and substance abuse. The first two pages of links displayed by each of three major search engines then were assessed for quality. RESULTS: A total of 240 Websites were evaluated. The mean score, the Quality Website Index (QWI), was 2.17 (SD = 3.3), (range from -16 [poorest] to +16 [best]). The overall quality of this group of Websites is rather poor, although there were several excellent sites. Websites located on the main search page had a significantly higher score than those in the sponsored section, and Websites based on standards had a significantly higher score than those that were not. CONCLUSION: Based on QWI scores, clinicians can recommend chronic pain Websites to provide their patients with accurate and pertinent information.

Responsiveness of patient-reported breathlessness during exercise in persistent asthma.

BACKGROUND: The purpose of the study was to examine the responsiveness of a computerized system whereby the patient reports spontaneously any change in the intensity of breathlessness during exercise. The hypotheses were that hypercapnia would increase and hyperoxia would decrease the slope of power production-breathlessness ratings compared with a control condition during cycle ergometry. METHODS: Thirty adult subjects (15 women and 15 men) with persistent asthma (mean [+/- SD] FEV(1)/FVC ratio, 57 +/- 10%) completed an initial familiarization visit and three study visits. All subjects inhaled two puffs of albuterol (180 microg) in order to standardize lung function prior to exercise. At visits 2 to 4, subjects breathed one of the three gas mixtures administered in a random order while performing a ramp exercise test. The experimental conditions were as follows: hypercapnia (5% carbon dioxide); hyperoxia (40% oxygen); and control (room air). RESULTS: Lung function was the same before and after exercise with the three experimental conditions. With hypercapnia, peak ventilation was increased, peak oxygen consumption, and power production were reduced, the slope of power-breathlessness was increased, and 25 patients (83%) reported breathlessness as the limiting symptom. With hyperoxia, peak ventilation was decreased, peak power production and the slope of power-breathlessness were unchanged, and 16 patients (53%) reported leg discomfort as the limiting symptom. CONCLUSIONS: Breathing 5% carbon dioxide altered physiologic responses and the slope of power production-breathlessness during exercise. The responses to hyperoxia were inconsistent. The continuous method for patient-reported breathlessness was responsive to hypercapnia, but not to hyperoxia, during incremental exercise.

Validity and responsiveness of the self-administered computerized versions of the baseline and transition dyspnea indexes.

BACKGROUND: Numerous instruments have been developed to examine the impact of activities on breathlessness. The primary purpose of this study was to examine the validity and responsiveness of the self-administered computerized (SAC) versions of the multidimensional baseline dyspnea index (BDI) and the transition dyspnea index (TDI). METHODS: Sixty-five patients with COPD who complained of exertional breathlessness were evaluated at an initial visit and after receiving standard therapy at two academic medical centers. Dyspnea scores from the SAC versions were compared with those obtained with the Medical Research Council (MRC) scale and with the original interview versions of the BDI and TDI. RESULTS: At the initial visit, all three dyspnea instruments showed similar correlations among themselves and with lung function. At the follow-up visit (mean [+/- SD] time after initial visit, 48 +/- 16 days), breathlessness scores were improved on all three instruments. Correlations were consistently higher for both versions of the TDI, and changes in lung function compared with corresponding values for DeltaMRC scale. Although 55% of patients reported no change in breathlessness on the MRC scale following treatment, the mean SAC and interview TDI scores were increased by 1.0 +/- 2.4 and 1.4 +/- 2.5, respectively, in these same patients. CONCLUSIONS: Both versions of the BDI and the MRC scale showed concurrent validity at the initial visit. The SAC TDI demonstrated responsiveness to standard therapy that was comparable with the findings of the interview TDI, but was better than that recorded with the MRC scale. The advantages of the SAC TDI include a patient-reported score on a continuous scale using computer technology.

Propionibacterium acnes biofilm is present in intervertebral discs of patients undergoing microdiscectomy.

BACKGROUND: In previous studies, Propionibacterium acnes was cultured from intervertebral disc tissue of ~25% of patients undergoing microdiscectomy, suggesting a possible link between chronic bacterial infection and disc degeneration. However, given the prominence of P. acnes as a skin commensal, such analyses often struggled to exclude the alternate possibility that these organisms represent perioperative microbiologic contamination. This investigation seeks to validate P. acnes prevalence in resected disc cultures, while providing microscopic evidence of P. acnes biofilm in the intervertebral discs. METHODS: Specimens from 368 patients undergoing microdiscectomy for disc herniation were divided into several fragments, one being homogenized, subjected to quantitative anaerobic culture, and assessed for bacterial growth, and a second fragment frozen for additional analyses. Colonies were identified by MALDI-TOF mass spectrometry and P. acnes phylotyping was conducted by multiplex PCR. For a sub-set of specimens, bacteria localization within the disc was assessed by microscopy using confocal laser scanning and FISH. RESULTS: Bacteria were cultured from 162 discs (44%), including 119 cases (32.3%) with P. acnes. In 89 cases, P. acnes was cultured exclusively; in 30 cases, it was isolated in combination with other bacteria (primarily coagulase-negative Staphylococcus spp.) Among positive specimens, the median P. acnes bacterial burden was 350 CFU/g (12 - ~20,000 CFU/g). Thirty-eight P. acnes isolates were subjected to molecular sub-typing, identifying 4 of 6 defined phylogroups: IA1, IB, IC, and II. Eight culture-positive specimens were evaluated by fluorescence microscopy and revealed P. acnes in situ. Notably, these bacteria demonstrated a biofilm distribution within the disc matrix. P. acnes bacteria were more prevalent in males than females (39% vs. 23%, p = 0.0013). CONCLUSIONS: This study confirms that P. acnes is prevalent in herniated disc tissue. Moreover, it provides the first visual evidence of P. acnes biofilms within such specimens, consistent with infection rather than microbiologic contamination.

Pain assessment in patients with low back pain: comparison of weekly recall and momentary electronic data.

UNLABELLED: Electronic data collection for monitoring pain has become increasingly popular in clinical research. Past research has shown that electronic diaries improve the timeliness of receipt of data, contribute to higher rates of compliance, and are preferred by patients over paper diaries, and this research suggests that electronic diaries that capture current pain at the moment of reporting result in more reliable ratings than recalled pain ratings. This study compared differences of momentary pain intensity ratings on an electronic visual analog scale (VAS) with weekly recalled pain on a 0 to 10 scale. We asked 21 patients with chronic low back pain to monitor their current pain at least once a day by using a VAS for up to 1 year with a palmtop computer. They were also called once a week and asked to rate their recalled weekly pain orally on a numeric scale from 0 to 10. Patients entered data electronically on average 357 times, for an average of 7.8 times a week. We found that (1) weekly recalled pain agreed highly (r > .90) with averaged momentary pain assessments, (2) neither frequency of electronic monitoring nor variability in momentary pain ratings (high standard deviations) contributed to degree of agreement between momentary and recalled pain, and (3) a ceiling effect was observed in VAS pain ratings as compared with numeric pain ratings. These findings suggest that, among many individuals, weekly recalled pain might be just as useful as momentary data collected through electronic data entry. PERSPECTIVE: Some believe that remembered pain is problematic because of recall bias and that data from frequent momentary pain ratings with electronic diaries are more valid. This study demonstrates that recalled pain is as valid as momentary data for many patients.

Continuous ratings of breathlessness during exercise by children and young adults with asthma and healthy controls.

Although it is recommended and common practise for adults with respiratory disease to rate symptoms (e.g., dyspnea and/or leg discomfort) during exercise testing, there are no reports on whether children can rate their perception of breathlessness during exercise. Our aims were to evaluate the ability of children and young adults with asthma to continuously rate breathlessness on the 0-10 category-ratio (CR-10) scale with a computerized system during cycle ergometry, and to compare their results with those of healthy subjects. At an initial visit, subjects were familiarized with equipment and exercise protocol, and practised rating breathlessness while cycling. At a follow-up visit (2-4 days later), subjects performed incremental exercise and rated breathlessness using a computer system, mouse, and monitor. Changing the position of the mouse caused movement of a vertical bar located adjacent to the CR-10 scale to indicate the severity of breathlessness. Baseline characteristics of the 14 subjects with asthma (age, 15 +/- 3 years) and 33 healthy subjects (age, 16 +/- 2 years) were similar. The two groups had comparable levels of fitness as measured by peak oxygen consumption (VO(2)). Correlations between exercise physiologic variables (power production, VO(2), and minute ventilation) and breathlessness ratings were >0.90. Subjects reported progressively more ratings of breathlessness with increasing exercise intensities. There were no differences between groups for slopes, x-intercepts, and absolute thresholds relating physiologic variables and breathlessness. In conclusion, children and young adults with asthma as well as healthy individuals of comparable age successfully used the computerized system to rate breathlessness continuously during cycle ergometry. Both groups reported more ratings of breathlessness with this technique as exercise progressed.

Prevalence of Propionibacterium acnes in Intervertebral Discs of Patients Undergoing Lumbar Microdiscectomy: A Prospective Cross-Sectional Study.

BACKGROUND: The relationship between intervertebral disc degeneration and chronic infection by Propionibacterium acnes is controversial with contradictory evidence available in the literature. Previous studies investigating these relationships were under-powered and fraught with methodical differences; moreover, they have not taken into consideration P. acnes' ability to form biofilms or attempted to quantitate the bioburden with regard to determining bacterial counts/genome equivalents as criteria to differentiate true infection from contamination. The aim of this prospective cross-sectional study was to determine the prevalence of P. acnes in patients undergoing lumbar disc microdiscectomy. METHODS AND FINDINGS: The sample consisted of 290 adult patients undergoing lumbar microdiscectomy for symptomatic lumbar disc herniation. An intraoperative biopsy and pre-operative clinical data were taken in all cases. One biopsy fragment was homogenized and used for quantitative anaerobic culture and a second was frozen and used for real-time PCR-based quantification of P. acnes genomes. P. acnes was identified in 115 cases (40%), coagulase-negative staphylococci in 31 cases (11%) and alpha-hemolytic streptococci in 8 cases (3%). P. acnes counts ranged from 100 to 9000 CFU/ml with a median of 400 CFU/ml. The prevalence of intervertebral discs with abundant P. acnes (≥ 1x103 CFU/ml) was 11% (39 cases). There was significant correlation between the bacterial counts obtained by culture and the number of P. acnes genomes detected by real-time PCR (r = 0.4363, p<0.0001). CONCLUSIONS: In a large series of patients, the prevalence of discs with abundant P. acnes was 11%. We believe, disc tissue homogenization releases P. acnes from the biofilm so that they can then potentially be cultured, reducing the rate of false-negative cultures. Further, quantification study revealing significant bioburden based on both culture and real-time PCR minimize the likelihood that observed findings are due to contamination and supports the hypothesis P. acnes acts as a pathogen in these cases of degenerative disc disease.

Responsiveness of continuous ratings of dyspnea during exercise in patients with COPD.

PURPOSE: To examine the responsiveness of a new computerized method for patients to provide continuous ratings of dyspnea during exercise in patients with chronic obstructive pulmonary disease (COPD). METHODS: In this randomized, double-blind study the effects of an inhaled bronchodilator (BD), albuterol/ipratropium bromide solution, were compared with normal saline (NS) in 30 patients with COPD (age, 66+/-9 yr; forced expiratory volume in 1 s, 48+/-14% pred). At visit 1, patients were familiarized with the cycle ergometer and computer, monitor, and mouse system to provide continuous ratings of dyspnea during exercise. At subsequent visits 2-3 d apart, patients performed pulmonary function tests followed by incremental ramp (15 W.min-1) and, 1 h later, constant work (at 55% of maximal work capacity) exercise tests. RESULTS: During incremental exercise the slopes of VO2:dyspnea and VE:dyspnea regressions were significantly lower, and patients exercised longer (Delta=0.4 min; P=0.003) with BD therapy compared with NS. During constant work exercise there was a significant reduction in dyspnea at the same exercise duration (5.0+/-2.8 vs 6.2+/-2.8 units on the 0-10 category-ratio scale; P=0.02) and patients exercised longer (Delta=0.9 min; P=0.04) with BD therapy. Changes in lung function at rest did not correlate significantly with changes in dyspnea ratings during exercise. CONCLUSIONS: Continuous ratings of dyspnea were responsive to inhaled bronchodilator therapy during both incremental and constant work exercise tests in patients with symptomatic COPD.

Prothrombin Time and Activated Partial Thromboplastin Time Testing: A Comparative Effectiveness Study in a Million-Patient Sample.

BACKGROUND: A substantial fraction of all American healthcare expenditures are potentially wasted, and practices that are not evidence-based could contribute to such waste. We sought to characterize whether Prothrombin Time (PT) and activated Partial Thromboplastin Time (aPTT) tests of preoperative patients are used in a way unsupported by evidence and potentially wasteful. METHODS AND FINDINGS: We evaluated prospectively-collected patient data from 19 major teaching hospitals and 8 hospital-affiliated surgical centers in 7 states (Delaware, Florida, Maryland, Massachusetts, New Jersey, New York, Pennsylvania) and the District of Columbia. A total of 1,053,472 consecutive patients represented every patient admitted for elective surgery from 2009 to 2012 at all 27 settings. A subset of 682,049 patients (64.7%) had one or both tests done and history and physical (H&P) records available for analysis. Unnecessary tests for bleeding risk were defined as: PT tests done on patients with no history of abnormal bleeding, warfarin therapy, vitamin K-dependent clotting factor deficiency, or liver disease; or aPTT tests done on patients with no history of heparin treatment, hemophilia, lupus anticoagulant antibodies, or von Willebrand disease. We assessed the proportion of patients who received PT or aPTT tests who lacked evidence-based reasons for testing. CONCLUSIONS: This study sought to bring the availability of big data together with applied comparative effectiveness research. Among preoperative patients, 26.2% received PT tests, and 94.3% of tests were unnecessary, given the absence of findings on H&P. Similarly, 23.3% of preoperative patients received aPTT tests, of which 99.9% were unnecessary. Among patients with no H&P findings suggestive of bleeding risk, 6.6% of PT tests and 7.1% of aPTT tests were either a false positive or a true positive (i.e. indicative of a previously-undiagnosed potential bleeding risk). Both PT and aPTT, designed as diagnostic tests, are apparently used as screening tests. Use of unnecessary screening tests raises concerns for the costs of such testing and the consequences of false positive results.

Comparison of continuous and discrete measurements of dyspnea during exercise in patients with COPD and normal subjects.

STUDY OBJECTIVES: The objectives of this study were as follows: (1) to compare results of the discrete and the continuous methods for measuring breathlessness; (2) to examine test-retest reliability; (3) and to test the hypothesis that patients with COPD have higher slopes and lower x-intercepts and absolute thresholds for power production, oxygen consumption (O(2)), and minute ventilation as independent variables and breathlessness ratings as the dependent variable, as compared with healthy subjects. DESIGN: Visit 1 (familiarization) and visit 2 and visit 3 (2 days apart) with randomized assignment of the discrete and continuous methods for subjects rating breathlessness during cycle ergometry. SETTING: Cardiopulmonary exercise laboratory in a university medical center. PARTICIPANTS: Twenty-four patients with COPD (mean age, 66 +/- 8 years [+/- SD]) and 24 healthy subjects (mean age, 66 +/- 10 years). INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Ratings of breathlessness on the Borg scale on cue with subjects moving and pressing the computer mouse button to indicate a rating (discrete method) or by moving the position of the mouse to adjust a vertical bar to indicate a change in breathlessness (continuous method). There were no significant differences in results between visit 2 and visit 3. Although peak exercise variables were similar with the discrete and continuous methods, both groups provided significantly more ratings of breathlessness with the continuous method. Patients with COPD exhibited higher slopes, lower x-intercepts, and lower absolute thresholds (breathlessness rating >/==" BORDER="0"> 0.5 ["just noticeable"] on the Borg scale) for power production and O(2)-breathlessness compared with healthy subjects (p < 0.05). CONCLUSIONS: Elderly patients with COPD and healthy subjects are able to use the continuous method successfully. Reliability is excellent for both methods. The continuous method provides a greater number of breathlessness ratings over the course of exercise, and allows the clinician to calculate an absolute threshold and just-noticeable differences. Regression parameters and absolute thresholds discriminate between patients with COPD and healthy subjects.

Usefulness of pain drawings in identifying real or imagined pain: accuracy of pain professionals, nonprofessionals, and a decision model.

UNLABELLED: The aim of this study was to determine the accuracy of pain specialists, nonprofessionals, and a decision model in judging whether a pain diagram was marked by a patient with chronic pain or by a healthy volunteer. Two hundred twenty-eight pain drawings were shown in random order to 10 pain medicine physicians, 10 pain medicine fellows, 10 nonphysician specialists, and 10 nonprofessionals. One half of the drawings (n = 114) had been produced by patients treated at a pain center and the other half (n = 114) by healthy individuals who were instructed to mark the diagrams as if they had a pain problem. The nonprofessionals were found to be 51.5% accurate, pain medicine fellows 52.7%, nonphysician specialists 54.3%, and pain medicine physicians 55.2 % accurate at distinguishing drawings by actual pain patients from drawings from volunteers without pain. A decision model was able to achieve 68.9% accuracy in determining which drawings were made by pain patients and which drawings were made by healthy individuals. The results suggest that subjective assessment of pain drawings alone is not useful in determining whether someone has real or imagined pain. A decision model that makes decisions on the basis of the number of highlighted squares on the pain diagram can identify real pain drawings with greater accuracy than humans. PERSPECTIVE: Pain drawings are clinically useful but have limitations. This study illustrates some of the benefits of computerized pain assessment and highlights the importance of not judging patients on the basis of one source of information.

Evaluation of dyspnea in the elderly.

The word "dyspnea" encompasses many different features. It can be considered to be a sensation, a symptom, or an illness. From a practical perspective many physicians and nurses use dyspnea to refer to difficult or labored breathing or an uncomfortable awareness of breathing. The American Thoracic Society recently defined dyspnea as a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity.

Mechanism of greater oxygen desaturation during walking compared with cycling in patients with COPD.

BACKGROUND: Patients with COPD exhibit greater oxyhemoglobin desaturation during walking than with cycling. The purpose of this investigation was to investigate differences in ventilatory responses and gas exchange as proposed mechanisms for this observation. METHODS: Arterial blood gas and lactate levels were measured in 12 patients with COPD (aged 68 ± 6 years) during incremental treadmill and cycle exercise. The primary outcome to assess the ventilatory response to exercise was Pao2. The primary outcome to assess impairment in exercise gas exchange was the difference between partial pressures of alveolar and arterial oxygen (Pao2 - Pao2). RESULTS: Pao2 in patients was significantly lower at peak exercise for treadmill walking (51.4 ± 6.8 mm Hg) compared with cycling (60.4 ± 10.7 mm Hg) (P = .002). The initial increase in Pao2 with cycling occurred prior to the onset of the anaerobic threshold. At peak exercise, Pao2 was significantly higher with cycling compared with walking (P = .004). The anaerobic threshold occurred at a lower oxygen consumption during cycling than walking (P = .001), and peak lactate levels were higher with cycling (P = .019). With progressive exercise, Pao2 - Pao2 increased similarly during treadmill and cycle exercise. CONCLUSIONS: The higher Pao2 during cycling minimized the magnitude of oxyhemoglobin desaturation compared with walking. The enhanced respiratory stimulation during cycling appears due to an initial neurogenic process, possibly originating in receptors of exercising muscles, and a subsequent earlier onset of anaerobic metabolism with higher lactate levels during cycling.

Advantages of endurance treadmill walking compared with cycling to assess bronchodilator therapy.

BACKGROUND: Walking is a familiar daily activity that is generally limited by breathlessness, whereas cycling is an uncommon physical effort typically limited by leg discomfort. The hypothesis was that patients with COPD would exhibit greater improvements in exercise endurance and relief of breathlessness with bronchodilator therapy during treadmill walking compared with cycling. METHODS: In this randomized, 2 x 2, double-blind, placebo-controlled, crossover trial, 20 patients with COPD (age, 64 +/- 7 years; FEV(1), 56 +/- 14% predicted) performed constant-load endurance exercise on the treadmill and cycle ergometer at 85% of capacity after inhaling normal saline (NS) or arformoterol (ARF) (15 microg). RESULTS: Increases in endurance times and consistency of responses were greater with treadmill walking (Delta: 157 +/- 286 s; P = .024; 80% improved) than with cycle exercise (Delta: 110 +/- 219 s; P = .038; 65% improved) with ARF compared with NS. However, these changes were not significantly different. The slope of breathlessness-time (mean Delta = -29%; P = .007) and the magnitude of oxygen desaturation were significantly lower with ARF compared with NS during treadmill, but not cycle, exercise. Inspiratory capacity values were similar between modes of exercise when comparing the same study medication. CONCLUSIONS: Improved endurance times support both constant-load treadmill and cycle exercise to assess the efficacy of bronchodilator therapy in patients with COPD. Unique differences in physiologic and perceptual responses with bronchodilation demonstrate advantages of treadmill walking as an exercise stimulus. TRIAL REGISTRATION: clinicaltrials.gov; Identifier: NCT00754546.