Occlusion Pressure

Rationale. Occlusion pressure (Pmo,0.1s) allows estimation of the respiratory drive (see Section 1 of this Statement).

Measurements. Measurements of Pmo,0.1 can be performed in sleeping supine infants (61, 62) and in awake seated children as soon as the child is able to breathe quietly with a noseclip and a mouthpiece, i.e., after 3-4 years of age (15). Even light sedation is not recommended in young children because it will affect the level of consciousness. A period of at least 5 minutes of regular breathing is required before performing occlusions at intervals of at least 1 minute. A mean of five acceptable occlusions is used to determine Pmo,0.1.

Advantages. Occlusion pressure is easily measured.

Disadvantages. It may be argued that the duration of pressure measurement over 100 milliseconds, as established in adults, is not appropriate in infants and children because of a shorter inspiration time (Ti) than in adults. However, Pmo,0.1 has been shown to be significantly related to the mean inspira-tory flow (Vt/Ti) in children from 4 to 16 years of age (15). States of alertness influence respiratory drive and therefore accurate measurements in infants should include determina tion of sleep state. There is a relatively high CV, 11.7% in children (15); variability has not been determined in infants.

Normal values. Occlusion pressure was found to be 4.4 cm H2O in full-term newborns (61, 62) and 3.6 cm H2O in preterm infants (62). Occlusion pressures are available in awake children from 4-16 years of age during resting breathing of room air (Table 3) (15). Pmo,0.1 decreases as a power function with age and reaches adult values at approximately 13 years of age.

Clinical application. Measurements of Pmo,0.1 are useful to assess respiratory drive in infants and children with chronic intrinsic loaded breathing (bronchopulmonary dysplasia [62], interstitial lung disease [63], chronic obstructive lung disease [16, 51, 64]).

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