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Position and ventilatory response to added dead space in prematurely born infants
Harish Rao1, Tolulope Saiki, Francesca Landolfo
1King's College London, MRC-Asthma Centre, Division of Asthma, Allergy and Lung Biology, London, UK.
Insights
Premature infants sleeping prone show slower breathing responses and weaker respiratory muscles compared to supine. This may increase their risk of sudden infant death syndrome (SIDS).
Area of Science:
- Neonatal physiology
- Respiratory control in infants
- Sudden Infant Death Syndrome (SIDS) research
Background:
- Premature infants face a higher risk of SIDS, particularly when placed in the prone (stomach-down) sleeping position.
- Existing research suggests potential differences in cardiorespiratory control mechanisms between prone and supine sleeping positions in this vulnerable population.
Purpose of the Study:
- To investigate the impact of sleeping position on respiratory control and muscle strength in preterm infants.
- To determine if prone sleeping exacerbates impaired responses to breathing challenges and reduces respiratory muscle function in premature infants.
Main Methods:
- A prospective study involving 25 infants with a median gestational age of 30 weeks.
- Infants were assessed in both supine and prone positions at a median of 36 weeks postmenstrual age.
- Measurements included breath-by-breath minute ventilation, response time constant to added dead space, maximum inspiratory occlusion pressure (MIOP), and P(0.1) to assess respiratory muscle strength.
Main Results:
- The time constant for respiratory response was significantly longer in the prone position (median 26 sec) compared to the supine position (median 22 sec).
- Maximum inspiratory occlusion pressure (MIOP) and P(0.1) were significantly lower in the prone position, indicating reduced respiratory muscle strength.
- These findings were statistically significant (P = 0.045 for time constant, P = 0.001 for MIOP, P = 0.003 for P(0.1)).
Conclusions:
- Premature infants exhibit a blunted ventilatory response to breathing challenges and diminished respiratory muscle strength when in the prone sleeping position.
- These physiological impairments in the prone position may contribute to the elevated risk of sudden infant death syndrome (SIDS) observed in preterm infants.
- The findings underscore the importance of understanding positional effects on infant respiratory control and SIDS prevention strategies.
Objectives:
Prematurely born infants are at increased risk of sudden infant death syndrome (SIDS) if slept prone.
Working Hypothesis:
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.
Study Design:
Prospective study. PATIENT-SUBJECT SELECTION: Twenty-five infants, median gestational age of 30 (range 26-32) weeks.
Methodology:
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.
Conclusion:
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.
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