Characteristics of the five sequential single breath-hold manoeuvres in 31 subjects
| Variables | Trial 1 | Trial 2 | Trial 3 | Trial 4 | Trial 5 | Average of 5 trials |
| Breath-hold time s | 5.5±0.6 (4.7–6.7) | 5.3±0.4 (4.7–6.0) | 5.3±0.5 (4.6–6.2) | 5.2±0.4 (4.6–6.0)* | 5.3±0.5 (4.6–6.5) | 5.3±0.4 (4.7–6.0) |
| Inspired volume L | 4.8±0.8 (3.0–6.8) | 4.7±0.8 (3.0–6.5) | 4.7±0.9 (2.9–6.4) | 4.8±0.9 (3.0–6.8) | 4.7±0.8 (3.0–6.4) | 4.7±0.8 (3.0–6.6) |
| Inspired volume % of FVC | 97.4±6.5 (80.7–108.9) | 97.0±6.2 (80.1–108.7) | 96.0±7.9 (77.5–109.3) | 97.9±6.4 (78.0–109.8) | 96.6±6.3 (76.5–109.5) | 97.0±6.0 (78.6–109.2) |
| Alveolar volume L | 6.6±1.1 (4.5–9.3) | 6.5±1.1 (4.5–9.4) | 6.4±1.1 (4.3–9.5)* | 6.5±1.2 (4.4–9.7) | 6.4±1.1 (4.4–9.4)* | 6.5±1.1 (4.4–9.4) |
| Inspired NO concentration ppm | 39.4±8.0 (11.8–53.1) | 41.2±5.9 (21.3–49.5) | 44.3±3.4 (38.5–50.9)* | 44.4±3.7 (31.9–49.8)* | 44.9±2.7 (38.8–50.0)* | 42.8±3.3 (31.7–49.4) |
| Expired NO concentration ppm | 3.7±1.4 (1.4–1.0) | 4.0±1.2 (1.2–1.8) | 4.2±1.2 (1.2–2.3)* | 4.4±1.0 (1.0–2.7)* | 4.4±1.1 (1.1–2.0)* | 4.2±1.1 (1.1–2.2) |
| Inspired CO concentration % | 0.28±0.00 (0.27–0.28) | 0.28±0.00 (0.27–0.28)* | 0.28±0.0 (0.27–0.28)* | 0.28±0.00 (0.27–0.28)* | 0.28±0.00 (0.27–0.28)* | 0.28±0.00 (0.27–0.28) |
| Expired CO concentration % | 0.13±0.01 (0.10–0.15) | 0.13±0.01 (0.10–0.15) | 0.13±0.01 (0.10–0.16) | 0.13±0.01 (0.12–0.15)* | 0.13±0.01 (0.11–0.16)* | 0.13±0.01 (0.11–0.15) |
| Inspired O2 concentration % | 19.0±0.3 (18.2–19.4) | 19.1±0.1 (18.9–19.3) | 19.1±0.1 (18.6–19.3) | 19.1±0.1 (18.9–19.3) | 19.1±0.1 (18.9–19.3) | 19.1±0.1 (18.8–19.3) |
| Expired O2 concentration % | 15.0±0.7 (13.2–16.0) | 15.0±1.0 (11.3–16.7) | 15.2±0.9 (12.6–16.8) | 15.2±0.9 (12.7–16.7) | 15.3±0.7 (13.7–16.7) | 15.1±0.7 (13.3–16.5) |
| Inspired He concentration % | 9.4±0.1 (9.1–9.6) | 9.4±0.1 (9.3–9.6)* | 9.4±0.1 (9.3–9.6)* | 9.4±0.1 (9.2–9.6)* | 9.4±0.1 (9.3–9.6)* | 9.4±0.1 (9.2–9.6) |
| Expired He concentration % | 6.3±0.4 (5.5–7.1) | 6.4±0.4 (5.6–7.2) | 6.4±0.4 (5.7–7.2) | 6.5±0.4 (5.6–7.2) | 6.5±0.4 (5.6–7.2)* | 6.4±0.4 (5.7–7.1) |
Data are presented as mean±sd (range). FVC: forced vital capacity; NO: nitric oxide; CO: carbon monoxide; O2: oxygen; He: helium. *: significantly different from trial one (p<0.05). The breath-hold time includes inspiration time plus apnoea time.