-
Table 1 shows the patient demographics and baseline characteristics. Ninety-one patients with COPD were divided into Group 1 (n = 27) and Group N (n = 64) according to their O2Pmax value. No significant differences in age, sex, body height, body mass index, smoking history, comorbidities, or medications were observed between the two groups. However, significant differences in body weight and classification of the airflow limitation were detected between the two groups (P < 0.05). The airflow limitation was more severe in Group 1 than in Group N.
Item Group 1 (n = 27) Group N (n = 64) All (n = 91) P-value Demographic Age (years) 65.1 ± 7.6 64.4 ± 7.3 64.6 ± 7.4 0.682 Male/Female (n) 23/4 52/12 75/16 0.652 Height (cm) 169.5 ± 5.4 167.4 ± 6.9 168.0 ± 6.5 0.167 Weight (kg) 73.9 ± 13.3 66.7 ± 9.3 68.9 ± 11.0 0.015 BMI (kg/m2) 24.8 ± 3.6 23.8 ± 3.1 24.1 ± 3.3 0.160 Smoking (n) 0.292 Non-smoker 4 (15%) 6 (9%) 10 (11%) Current smoker 20 (74%) 42 (66%) 62 (68%) Ex-smoker 3 (11%) 16 (25%) 19 (21%) GOLD (n) n (27) n (64) 0.014 I 1 (4%) 8 (13%) 9 (10%) II 14 (52%) 43 (67%) 57 (63%) III 9 (33%) 13 (20%) 22 (24%) IV 3 (11%) 0 (0%) 3 (3%) Comorbidities (n) n (22) n (53) 0.398 Hypertension 8 28 36 CHD 4 6 10 Type 2 diabetes 9 14 23 Hypercholesterolemia 1 5 6 Medications for COPD (n) n (27) n (64) 0.716 None 16 37 53 LABA 1 2 LAMA 1 7 LABA + LAMA 0 1 LABA + ICS 2 7 LABA + LAMA + ICS 7 10 Medications for CVD (n) n (13) n (45) 0.680 Beta-blockers 3 14 Aspirin 1 6 ACEI 1 1 CCB 3 12 ARBs 3 4 Statin 2 8 Note. Data are presented as mean ± standard deviation or numbers (percentage). All demographic data except sex were compared using the t-test. Other data were compared using the chi-square test. Bold numbers indicate a significant difference (P < 0.05) between the two groups. Abbreviations: BMI, body mass index; GOLD, Global Initiative for Chronic Obstructive Lung Disease; CHD, coronary heart disease; LABA, long-acting beta 2 agonist; LAMA, long-acting antimuscarinic antagonist; ICS, inhaled corticosteroid; CVD, cardiovascular disease; ACEI, angiotensin-converting enzyme inhibitor; CCB, calcium channel blocker; ARB, angiotensin receptor blocker. Table 1. Baseline characteristics of Group 1 (O2Pmax < 80% predicted) and Group N (O2Pmax ≥ 80% predicted)
-
Table 2 shows the static lung function parameters. Patients with a lower O2Pmax had lower FVC%, VC%, FEV1%, and FEV1/FVC% values (P < 0.05).
Item Group 1
(n = 27)Group N
(n = 64)All
(n = 91)P-value FVC (% predicted) 75.00 ± 16.67 86.80 ± 16.57 83.30 ± 1.82 0.003 VC (% predicted) 72.55 ± 16.34 84.45 ± 16.29 80.92 ± 1.79 0.003 FEV1 (% predicted) 51.49 ± 20.33 63.79 ± 16.15 60.14 ± 1.92 0.003 FEV1/FVC (%) 52.25 ± 13.07 58.34 ± 10.46 56.53 ± 1.21 0.038 RV/ TLC (%) 0.57 ± 0.11 0.55 ± 0.17 0.56 ± 0.02 0.618 PEF (% predicted) 60.81 ± 24.02 69.80 ± 21.70 67.14 ± 2.37 0.084 MMEF75/25(% predicted) 20.03 ± 11.40 24.01 ± 11.00 22.83 ± 1.17 0.121 TLCO/VA (% predicted) 73.41 ± 26.16 81.11 ± 21.56 78.83 ± 2.43 0.148 Note. Data are presented as mean ± standard deviation. Data were compared using the t-test. Bold numbers indicate a significant difference (P < 0.05) between the two groups. Abbreviations: FVC, forced vital capacity; VC, vital capacity; FEV1, forced expiratory volume in 1 s; RV, residual volume; TLC, total lung capacity; PEF, peak expiratory flow; MMEF75/25, maximal mid-expiratory flow rate 75/25; TLCO/VA, transfer factor of the lungs for carbon monoxide/alveolar volume. Table 2. Differences in the static lung function test parameters between Group 1 (O2Pmax < 80% predicted) and Group N (O2Pmax ≥ 80% predicted)
-
Table 3 shows the CPET variables. AT, WR, V̇O2, V̇O2/kg, HR, systolic BP, diastolic BP, V̇E, BR, and EqCO2 were measured at the AT and maximum exercise during CPET. HRR1 was calculated after the exercise. Significant differences in AT, WR%, V̇O2%, V̇O2/kg%, V̇E%, EqCO2AT, and EqCO2max were observed between the two groups (P < 0.05). Among these variables, EqCO2AT and EqCO2max were higher in patients with impaired O2Pmax, whereas the other variables were lower. Significant differences were also detected in HRR1 (P < 0.05), which was regarded as a circulatory parameter.
Item Group 1 (n = 27) Group N (n = 64) All (n = 91) P-value AT (%) 37.92 ± 9.34 54.51 ± 11.85 49.59 ± 13.47 < 0.001 WR (% predicted) 57.67 ± 15.07 90.84 ± 22.92 81.00 ± 25.80 < 0.001 V̇O2 (% predicted) 55.37 ± 8.21 77.86 ± 13.37 71.19 ± 15.85 < 0.001 V̇O2/kg (% predicted) 54.78 ± 8.37 77.63 ± 12.18 70.85 ± 15.31 < 0.001 HRAT (beats/min) 106.70 ± 12.14 106.83 ± 14.06 106.79 ± 13.45 0.968 HRmax (beats/min) 130.59 ± 16.70 130.86 ± 18.80 130.78 ± 13.11 0.949 SBPAT (mmHg) 140.96 ± 24.68 137.53 ± 23.47 138.55 ± 23.75 0.542 SBPmax (mmHg) 167.63 ± 23.07 161.31 ± 31.08 163.19 ± 28.95 0.345 DBPAT (mmHg) 81.19 ± 12.57 83.77 ± 18.98 83.00 ± 17.30 0.519 DBPmax (mmHg) 90.41 ± 17.47 94.94 ± 29.50 93.58 ± 26.45 0.460 V̇E (% predicted) 47.26 ± 11.73 62.83 ± 14.02 58.21 ± 15.12 < 0.001 BRAT (mL/min) 42.56 ± 18.74 50.94 ± 14.03 48.45 ± 15.94 0.043 BR (% predicted) 71.11 ± 70.12 73.14 ± 64.31 72.54 ± 65.70 0.894 EqCO2AT 35.65 ± 6.05 32.33 ± 4.94 33.31 ± 5.48 0.007 EqCO2max 34.10 ± 6.93 30.93 ± 5.86 31.87 ± 6.32 0.028 HRR1 (beats/min) 14.78 ± 7.66 19.28 ± 9.66 17.95 ± 9.30 0.034 Note. Data are presented as mean ± standard deviation. Data were compared using the t-test. Bold numbers indicate a significant difference (P < 0.05) between the two groups. Abbreviations: AT, anaerobic threshold; WR, work rate; V̇O2, oxygen uptake; V̇O2/kg, oxygen uptake per kilogram; HR, heart rate; SBP, systolic blood pressure; DBP, diastolic blood pressure; V̇E, minute ventilation; BR, breathing reserve; EqCO2, ventilatory equivalent for carbon dioxide; HRR1, heart rate recovery after 1 min of rest. Table 3. Differences in the CPET parameters between Group 1 (O2Pmax < 80% predicted) and Group N (O2Pmax ≥ 80% predicted)
-
Table 4 shows the CAT, mMRC, Borg CR10 scale, and SGRQ scores. The Borg CR10 scale, SGRQ total, SGRQ symptom, and SGRQ activity scores were significantly higher in Group 1 than those in Group N (P < 0.05).
Item Group 1 (n = 27) Group N (n = 64) All (n = 91) P-value CAT (points) 12.50 ± 5.32 9.79 ± 4.01 10.79 ± 4.66 0.084 mMRC (points) 1.71 ± 0.73 1.29 ± 0.76 1.45 ± 0.76 0.099 Borg CR10 (points) 2.64 ± 1.21 1.56 ± 1.45 1.96 ± 1.45 0.025 SGRQ, total (points) 41.78 ± 12.46 25.61 ± 17.15 33.31 ± 16.89 0.024 SGRQ, symptom (points) 54.30 ± 19.34 29.47 ± 17.51 41.29 ± 21.98 0.006 SGRQ, activity (points) 55.89 ± 11.11 35.65 ± 25.67 45.29 ± 22.19 0.032 SGRQ, impact (points) 33.57 ± 15.99 19.66 ± 15.12 26.28 ± 16.73 0.055 Note. Data are presented as mean ± standard deviation. Data were compared using the t-test. Bold numbers indicate a significant difference (P < 0.05) between the two groups. The CAT, mMRC, and SGRQ were evaluated before CPET; the Borg CR10 was evaluated immediately after CPET. Abbreviations: CAT, COPD Assessment Test; mMRC, modified Medical Research Council scale; Borg CR10, Borg’s 10-point category-ratio scale; SGRQ, St. George’s Respiratory Questionnaire. Table 4. Differences in the dyspnea scores between Group 1 (O2Pmax < 80% predicted) and Group N (O2Pmax ≥ 80% predicted)
-
Figure 1 shows the correlation coefficients between O2Pmax and FEV1/FVC%, FEV1%, and FVC%, which were regarded as lung ventilation function variables. O2Pmax was slightly but significantly correlated with FEV1/FVC% (r = 0.207, P < 0.05), FEV1% (r = 0.267, P < 0.05), and FVC% (r = 0.288, P < 0.01).
-
Figure 2 shows the correlation coefficients between O2Pmax and the CPET variables. O2Pmax was positively correlated with AT (r = 0.623, P < 0.001), WR% (r = 0.613, P < 0.001), V̇O2max% (r = 0.681, P < 0.001), V̇O2/kgmax% (r = 0.707, P < 0.001), and V̇Emax% (r = 0.399, P < 0.001), but negatively correlated with EqCO2AT (r = −0.302, P < 0.01) and EqCO2max (r = −0.214, P < 0.05).
-
Table 5 shows that FVC%, FEV1%, O2Pmax%, WRmax, and V̇O2max were significantly lower in the AE2 group than in the AE1 group (P < 0.05).
Item AE1 group (n = 30) AE2 group (n = 27) P-value Age (Years) 63.73 ± 8.09 64.30 ± 6.92 0.780 Weight (kg) 69.00 ± 8.60 70.48 ± 13.83 0.625 Smoke (numbers) 27.50 (40.75) 15.00 (30.00) 0.257 Male/Female (n) 25/5 23/4 0.261 FVC (% predicted) 87.08 ± 16.94 76.84 ± 13.88 0.016 FEV1 (% predicted) 63.52 ± 16.25 51.52 ± 17.78 0.010 FEV1/FVC (%) 57.44 ± 9.26 52.12 ± 13.13 0.080 O2Pmax (% predicted) 93.23 ± 13.10 79.93 ± 15.41 0.001 WRmax (watts) 101.70 ± 21.63 80.48 ± 24.66 0.001 V̇O2max (mL/min) 1350.23 ± 230.16 1141.15 ± 279.00 0.003 Note. Data are presented as mean ± standard deviation, median (IQR), or number. Sex was compared using the chi-square test, smoke was compared using the Mann-Whitney test, and the remaining data were compared using the t-test. Bold numbers indicate a significant difference (P < 0.05) between the two groups. Abbreviations: AE, acute exacerbation; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s; O2P, oxygen pulse; WR, work rate; V̇O2, oxygen uptake. Table 5. Characteristics, pulmonary function, and CPET data of the patients with COPD grouped in acute exacerbation
-
The univariate logistic regression confirmed that O2Pmax was an independent predictor of AECOPD [odds ratio (OR), 1.068; 95% CI, 1.023–1.116; P = 0.003]. Five variables (FVC%, FEV1%, O2Pmax, WRmax, and V̇O2max) were used to build a logistic regression model to predict AECOPD in a multivariate analysis (Tables 6-7). Only O2Pmax was a predictor of AECOPD (OR = 1.062, 95% CI = 1.012–1.114, P = 0.015). ROC curve analysis was applied to categorize the optimal cut-off value of O2Pmax for exacerbation (Figure 3). The AUC was 0.739 (95% CI = 0.609–0.869, P = 0.002). The cut-off value was 89.5%, with a sensitivity of 63.30% and a specificity of 77.80%.
Item β P-value OR 95% CI FVC (% predicted) 0.012 0.724 1.012 (0.949–1.078) FEV1 (% predicted) 0.004 0.898 1.004 (0.946–1.065) O2Pmax (% predicted) 0.060 0.015 1.062 (1.012–1.114) WRmax (watts) 0.052 0.215 1.053 (0.970–1.143) V̇O2max (mL/min) –0.002 0.608 0.998 (0.992–1.005) Note. Only O2Pmax had a predictive effect for AECOPD (OR = 1.062, 95% CI = 1.012–1.114, P = 0.015). Bold numbers indicate a significant difference (P < 0.05). Abbreviations: FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s; O2P, oxygen pulse; WR, work rate; V̇O2, oxygen uptake; OR, odds ratio; CI, confidence interval. Table 6. Multivariate logistic regression analysis of lung function and the CPET data in patients with AECOPD
Item β P-value OR 95% CI O2Pmax (% predicted) 0.066 0.003 1.068 (1.023–1.116) Note. O2Pmax was a predictor of AECOPD (OR = 1,068, 95% CI = 1.023–1.116, P = 0.003). The bold number indicates a significant difference (P < 0.05) between the two groups. Abbreviations: OR, odds ratio; CI, confidence interval. Table 7. Univariate logistic regression analysis of O2Pmax in patients with AECOPD
Effect of Maximal Oxygen Pulse on Patients with Chronic Obstructive Pulmonary Disease
doi: 10.3967/bes2022.107
- Received Date: 2022-05-08
- Accepted Date: 2022-08-03
-
Key words:
- Oxygen pulse /
- Chronic obstructive pulmonary disease /
- Cardiopulmonary exercise test /
- Acute exacerbation
Abstract:
The authors declare that they have no competing interests.
Citation: | LI Yun Xiao, WANG Jun, WU Bo, LIN Fang, TAN Chun Ting, YU Gang Gang, NIE Shan, ZHAO Ran Ran, XU Bo. Effect of Maximal Oxygen Pulse on Patients with Chronic Obstructive Pulmonary Disease[J]. Biomedical and Environmental Sciences, 2022, 35(9): 830-841. doi: 10.3967/bes2022.107 |