Position and ventilatory response to added dead space in prematurely born infants.
OBJECTIVE
Prematurely born infants are at increased risk of sudden infant death syndrome (SIDS) if slept prone.


OBJECTIVE
Prematurely born infants would have an impaired response to an added dead space and lower respiratory muscle strength in the prone compared to the supine position.


METHODS
Prospective study. PATIENT-SUBJECT SELECTION: Twenty-five infants, median gestational age of 30 (range 26-32) weeks.


METHODS
The infants were studied supine and prone at a median of 36 weeks postmenstrual age. Breath by breath minute volume was measured at baseline and after a dead space was incorporated into the breathing circuit; the time constant of the response was calculated. The maximum inspiratory occlusion pressure generated (MIOP) and the pressure generated over the first 100 msec (P(0.1)) during airway occlusion were assessed.


RESULTS
The median time constant was longer (26 (range 8-106) sec vs. 22 (range 6-92) sec (P = 0.045)) and the median MIOP (P = 0.001) and P(0.1) (P = 0.003) were lower in the prone compared to the supine position.


CONCLUSIONS
Prematurely born infants have a dampened response to tube breathing and reduced respiratory muscle strength in the prone compared to the supine position, which may contribute to their increased vulnerability to SIDS in the prone position.
Rao
Harish
H
King's College London, MRC-Asthma Centre, Division of Asthma, Allergy and Lung Biology, London, UK.
Saiki
Tolulope
T
Landolfo
Francesca
F
Smith
Adam P R
AP
Hannam
Simon
S
Rafferty
Gerrard F
GF
Milner
Anthony D
AD
Greenough
Anne
A
D000222:Adaptation, Physiological; D004867:Equipment Design; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight / Q000502:physiology*; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D053580:Muscle Strength; D016684:Prone Position; D011446:Prospective Studies; D012126:Respiratory Dead Space; D012129:Respiratory Function Tests / Q000295:instrumentation / Q000379:methods*; D012132:Respiratory Muscles / Q000502:physiology*; D016683:Supine Position