Background: Patients suffering from congenital heart disease often may not follow classical standardized
cardiopulmonary exercise test (CPET) on a treadmill or bicycle due to insufficiency
or mental or physical disability.
Method: We developed a new CPET for these patients based on a 6MWT allowing individual speed
combined with a mobile telemetric spiroergometry. In addition to 6MWT distance and
Borg dyspnea index, oxygen uptake (VO2/kg), CO2 production as well as heart rate (HR), breathing frequency (BF) and -minute volume
(VE), pulse oxymetry, and ECG could be recorded.
Results: In a pilot study, we strained 26 healthy volunteers both by regular treadmill CPET
(DGPK protocol) and our modified 6MWT in random order on 2 subsequent days. The setup
was validated by 28 patients recruited from our GUCH outpatient clinic.
|
No.
|
Gender
|
Age [years]
|
Height [cm]
|
Weight [kg]
|
|
Volunteers
|
26
|
12 males, 14 females
|
24.3 ± 4.4
|
175 ± 8
|
70.69 ± 12.1
|
|
Patients
|
28
|
14 males, 14 females
|
23.1 ± 7.4
|
171 ± 12
|
66.5 ± 16.4
|
Biometrical data: (mean ± SD). Statistically there were no biometrical differences.
Test data: (mean ± SD). AT = anaerobic threshold, max = maximum.
|
VO2/kg/minAT [mL/kg/min]
|
VO2/kg/min-max [mL/kg/min]
|
O2/HR-AT [mL]
|
OUES
|
HR-AT [/min]
|
BFAT [/min]
|
VEAT [L/min]
|
|
Treadmill
|
24.4 ± 7.2
|
41.2 ± 11.1
|
12.1 ± 3.8
|
2.89 ± 0.96
|
137.2 ± 22.0
|
25.3 ± 6.7
|
40.5 ± 15.1
|
|
6MWT
|
23.2 ± 6.9
|
32.1 ± 10.3
|
11.3 ± 3.7
|
2.94 ± 1.17
|
141.9 ± 24.6
|
32.0 ± 9.3
|
44.8 ± 16.1
|
|
r
|
0.67
|
0.74
|
0.74
|
0.81
|
0.52
|
0.53
|
0.54
|
In linear regression analysis, best correlation was found for oxygen uptake efficiency
slope (OUES), oxygen uptake (VO2/kg/min) at anaerobic threshold and maximum.
Conclusion: Although our modified 6MWT is a test at submaximal effort at anaerobic threshold,
it correlates well to classical treadmill test enabling CPET even in physically or
mentally handicapped patients, and may serve as substitute for 'classical' treadmill
test.
