Table 1—

Pulmonary function and sleep data of the index case’s family

VariableIndex caseFatherMotherSibling 2Sibling 3Sibling 4Sibling 5
Age yrs at sleep study11/1940/4738/4514/2111/166/104/8
BMI kg·m-225.425.830.324.929.615.616.8
Arterial blood gas analysis
Pa,O2 kPa14.6#10.9NA13.510.5NANA
Pa,CO2 kPa6.47.1NA6.48.1NANA
 Bicarbonate mmol·L-129.129.6NA31.532.2NANA
Sleep studies
 Mean Sa,O291/9190/8994/9592/8392/9197/9889/92
 Min Sa,O271/8567/7583/8277/5881/8196/9776/85
 Desats >4%27/2565/1207/127/2971/68+/+35/+
 Epworth score11215NANA
Ventilatory drive studies
V′R,CO2 L·min-1·kPa-1ƒ1.
  • Data are presented as that obtained from the initial/follow-up sleep studies, unless otherwise stated. M: male; F: female; BMI: body mass index; Pa,O2: arterial oxygen tension; Pa,CO2: arterial carbon dioxide tension; Sa,O2: arterial oxygen saturation; Desats >4%: number of desaturations >4% during the overnight sleep study; AHI: apnoea/hypopnoea index; NA: not available; VR,CO2, ventilatory response to progressive hypercapnia. #: arterial blood gas analysis performed while on oxygen therapy at 2 L·breaths·min-1; : data unavailable because of refusal (mother) or could not be performed (child 4 and 5); +: sleep studies were repeated in the two younger family members after a shorter interval; §: apnoeic and hypopnoeic events were predominantly (>80%) obstructive in nature; ƒ: normal range for the current authors’ centre (St Vincent's University Hospital, Dublin, Ireland) is 5–40.