Polysomnography (PSG) in children with NMD
PSG data were available within 6 months of spirometry for the 30
children with NMD. Mean (±SD) total sleep time was 351±8.8 min. The
total AHI was 6.9 ±5.9/hour, obstructive AHI was 5.2±4.2 /hour and REM
AHI 14.1±5.3 /hour. Only 2 children [7%] had a normal total AHI
[<1/hr].(25) The average
baseline SpO2 was 96 SD±5% and minimum saturation for
the entire cohort was 88.4 SD±4.2%. The mean baseline transcutaneous
[Tc] CO2 was 44mmHg (SD±5). The rise in
TcCO2 from NREM to REM sleep in the entire cohort was 6
mmHg (SD±2.7) (Table 6).
Eight children with NMD were already established on non-invasive
ventilation (NIV) when they were studied. Indications for NIV included
recurrent chest infections requiring paediatric intensive care unit
admissions (n=2) or evidence of sleep disordered breathing (n=6). The
TcCO2 rise from NREM to REM sleep of 5 vs 9 mmHg, for
children breathing spontaneously compared to those on nocturnal NIV.
There was no significant correlation between postural changes in
spirometry and the rise in CO2 from NREM to REM
sleep on PSG for the group as a whole (r-=0.04, p=0.8), the group
spontaneously breathing (r=0.02, p=0.9),
or for those established on NIV (r=0.13,p=0.74). The healthy controls
did not have polysomnograms.