Abstract
The effect of PEEP on lung mechanics and on the work of breathing was studied in 8 preterm lambs delivered by cesarean section at 134 days gestation. Indwelling arterial, venous, and tracheal cannulae were placed before clamping the cord. Assisted mechanical ventilation was performed at a tidal volume of 15/ml/Kg and a rate of 30-40/min at FIO2 of 0.95. Measurements of intraesophageal and tracheal pressures, air flow, tidal volume, and functional residual capacity enabled calculation of dynamic compliance (CL), specific compliance (CS), inspiratory resistance (RI), expiratory resistance (RE), and work of breathing at 0, 3, 6, and 10 cm H2O PEEP. Dynamic compliance and CS decreased by 0.11 ml/cm H2O/Kg and 0.0051 1/cm H2O per cm H2O PEEP respectively for PEEP above 3 cm H2O. Functional residual capacity increased (p<0.005) by 1.6 ml/Kg per cm H2O PEEP. Inspiratory resistance increased significantly (p<0.05) only between 0 and 6 cm H2O PEEP while RE increased (p<0.05) between 0 and all higher levels of PEEP (3, 6, and 10 cm H2O). As compared to 0 cm H2O PEEP (11.9 ± 2.5 SE × 106 ergs/min), the work of inspiration per unit time decreased 17% at 3 cm H2O and increased 10% and 80% at 6 and 10 cm H2O PEEP respectively. These data suggest that it is mechanically easier to breathe at low levels of PEEP (3 cm H2O) than without PEEP or at high levels of PEEP (10 cm H2O).(Supported by USPHS Grants HL19402 & HL15061)
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Shaffer, T., Koen, P., Ferguson, J. et al. ALTERATIONS IN LUNG MECHANICS AND THE WORK OF BREATHING OF PRETERM LAMBS ON POSITIVE END EXPIRATORY PRESSURE (PEEP). Pediatr Res 11, 579 (1977). https://doi.org/10.1203/00006450-197704000-01253
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DOI: https://doi.org/10.1203/00006450-197704000-01253