Assessment of Respiratory Function and Need for Noninvasive Ventilation in a Cohort of Patients with Myotonic Dystrophy Type 1 Followed at One Single Expert Center
Table 4
Detailed respiratory features of the 2 cohorts according to NIV indication.
n
Cohort 1 (n = 84)
n
Cohort 2 (n = 67)
p value
No NIV indication
NIV indication at baseline
Median [IQR]
Median [IQR]
Nocturnal oximetry
Mean SpO2
65
96.00 [94.40–97.30]
63
92.40 [90.30–94.10]
<0.0001
Min SpO2
61
88.00 [84.00–92.00]
61
80.00 [71.00–84.00]
<0.0001
ODI
58
1.40 [0.20–3.80]
63
14.80 [6.30–21.70]
<0.0001
Morning ABG
pH
59
7.47 [7.44–7.49]
62
7.43 [7.42–7.46]
<0.0001
pCO2
59
39.50 [35.60–43.80]
63
45.00 [42.00–48.30]
<0.0001
pO2
59
89.40 [78.60–101.60]
63
77.20 [67.40–85.20]
<0.0001
HCO3-
59
29.30 [26.70–31.60]
62
31.35 [28.60–33.00]
0.0116
Spirometry
FVC % sitting
84
89.00 [74.50–99.50]
67
72.00 [59.00–88.00]
<0.0001
FVC % supine
78
83.80 [72.00–97.00]
53
68.00 [49.00–82.00]
<0.0001
FEV1%
70
81.00 [71.00–96.00]
59
72.00 [55.00–83.00]
0.0033
FEV1/FVC
70
0.80 [0.76–0.84]
59
0.81 [0.75–0.86]
0.4156
∆ FVC
78
4.00 [0.00–8.00]
53
8.00 [4.00–14.00]
0.0001
PCEF
84
343.50 [289.50–417.00]
65
303.80 [256.00–365.00]
0.0145
MIP
40
61.50 [44.00–89.50]
18
43.00 [28.00–60.00]
0.0253
MEP
40
79.00 [53.00–103.00]
18
58.00 [36.00–75.00]
0.1047
6MWT
Meters
60
458.50 [390.00–528.00]
43
315.00 [240.00–375.00]
<0.0001
Mean O2 saturation
47
97.00 [95.00–98.00]
27
93.00 [88.00–95.00]
<0.0001
Pretest dyspnea
51
0.00 [0.00–0.00]
27
0.00 [0.00–2.00]
0.2901
Post-test dyspnea
51
2.00 [1.00–3.00]
27
3.00 [2.00–5.00]
0.1515
Secretion management
Air stacking
9
(10.7)
6
(9)
0.7897
Cough assist
2
(2.4)
6
(9)
0.1395
IQR, interquartile range; SpO2, oxygen saturation; ODI, Oxygen Desaturation Index; pH, potential of hydrogen; pCO2, partial pressure of carbon dioxide; pO2, partial pressure of oxygen; HCO3-, bicarbonate; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 second; PCEF, peak cough expiratory flow; MIP, maximal inspiratory pressure; MEP, maximal expiratory pressure; 6MWT, six-minute walk test; NIV, noninvasive ventilation. Pretest dyspnea and post-test dyspnea were calculated using the modified dyspnea Borg scale. This scale asks the patient to rate the difficulty of breathing from 0 (no difficulty) to 10 (maximal difficulty) at the very beginning of the 6MWT and immediately after. percentage.
