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 2

Respiratory features of the whole cohort at baseline (n = 151).

	n	Median [IQR]
Nocturnal oximetry
Mean SpO2	128	94.35 [92.35–96.30]
Min SpO2	122	84.00 [77.00–89.00]
ODI	121	4.30 [1.30–15.20]
Morning ABG
pH	121	7.45 [7.43–7.48]
pCO2	122	42.20 [38.30–46.60]
pO2	122	81.85 [70.40–92.60]
HCO3-	121	29.90 [27.80–32.70]
Spirometry
FVC % sitting	151	80.00 [67.00–97.00]
FVC % supine	131	79.00 [63.50–89.00]
FEV1%	129	76.00 [63.00–91.10]
FEV1/FVC	129	0.80 [0.76–0.84]
∆ FVC %	131	6.00 [2.00–10.00]
PCEF	149	323.00 [272.40–402.00]
MIP	58	56.50 [37.00–79.00]
MEP	58	69.00 [50.00–102.00]
6MWT
Meters	103	391.00 [315.00–500.00]
Mean O2 saturation	74	95.00 [93.00–97.00]
Pretest dyspnea	78	0.00 [0.00–0.00]
Post-test dyspnea	78	2.00 [1.00–4.00]
NIV indication
No indication	84	55.6
Baseline indication	67	44.4
Secretion management
Air stacking, yes	15	9.9
Cough assist, yes	8	5.3

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.