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Continuous positive airway pressure reduces loop gain and resolves periodic central apneas in the lamb

Bradley A Edwards1, Scott A Sands, Clare Feeney

  • 1Ritchie Centre for Baby Health Research, Monash Institute of Medical Research, Monash University, Monash Medical Centre, Clayton 3168, Australia.

Respiratory Physiology & Neurobiology
|July 21, 2009
PubMed

Insights

Continuous positive airway pressure (CPAP) stabilizes infant breathing by reducing loop gain, effectively treating apnea of prematurity. This therapy increases lung volume, ameliorating respiratory distress and central apneas in newborns.

Area of Science:

  • Neonatal physiology
  • Respiratory control mechanisms
  • Pulmonary medicine

Background:

  • Continuous positive airway pressure (CPAP) is a standard treatment for infant respiratory distress syndrome and apnea of prematurity.
  • The precise physiological mechanisms by which CPAP exerts its therapeutic effects remain incompletely understood.
  • A key hypothesis suggests CPAP stabilizes respiratory control by reducing loop gain (LG).

Purpose of the Study:

  • To investigate the effect of CPAP on loop gain (LG) in a lamb model of periodic breathing (PB).
  • To determine if CPAP administration can reduce the duration and severity of experimentally induced PB.

Main Methods:

  • Periodic breathing (PB) was experimentally induced in lambs.
  • Varying levels of CPAP (0, 2.5, 5, and 10 cmH2O) were applied.
  • PB epoch duration and duty ratio were measured as surrogate markers for LG.

Main Results:

  • CPAP significantly reduced PB epoch duration in a dose-dependent manner (p<0.001).
  • The duty ratio of PB significantly increased with increasing CPAP levels (p<0.001).
  • These findings indicate that CPAP decreases loop gain (LG).

Conclusions:

  • CPAP ameliorates the effects of recurrent central apneas by decreasing loop gain (LG).
  • The mechanism involves CPAP-induced increases in lung volume.
  • CPAP may also be beneficial for mixed and obstructive apneas through this mechanism.

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