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High Frequency Nasal CPAP
High Frequency nCPAP Provides Adequate Prolonged Support of the Preterm Lamb: Null DM, O’Brien EA, Dahl MJ, et al. Presented as a late breaking platform presentation at the 2004 PAS Meeting.
Background: In preterm lambs, the use of high frequency nasal continuous positive airway pressure (nCPAP) instead of conventional ventilation (CV) over a 21-day period enhances alveolar septation and significantly affects expression of key genes involved in lung morphogenesis, such as VEGF, Flk-1, glucocorticoid receptor, and p53. Changes in molecular expression are evident at 72 h of continuous support.
Objective: Physiologic studies using nCPAP and the preterm lamb have been limited to <12 h (Jobe, Pediatr Res 52:387, 2002), so the physiological effects of 72 h of NCPAP are unknown. Our objective was to supplement our recent histological and molecular findings with the physiologic consequences of 72 h of nCPAP versus CV support.
Methods: Preterm lambs were delivered at ~ 132 days of gestation (treated with antenatal steroids and postnatal surfactant). The lambs were managed by either CV (control; n=6) or nCPAP (n=5) for 72 h. At 24, 48 and 72 h of life, we determined the p02, pC02, pH, A-a gradient, and oxygenation index (OI).
Results: With the exception of lowering pH in the nCPAP group at 24 h, no significant differences existed in respiratory parameters between the lambs treated with CV or nCPAP. The A-a gradient significantly decreased in the lambs treated with nCPAP from 24 to 72 h.
Conclusion: Using high frequency nCPAP, we are able to support preterm lambs over a 72 h period without compromising their respiratory status. Our ability to adequately maintain these lambs allows further study into the molecular mechanisms through which prolonged nCPAP permits enhanced alveolar septation.
Comment: Nasal SIMV and now nasal HFOV! Without doubt, the first case reports of this modality for preterm infants will soon appear. The fundamental issue of interest is whether a strategy of rapid extubation of infants with some means of positive pressure support will improve the survival and decrease morbidity in preterm infants. We all believe that we can reduce the number of days of intubation through aggressive alternative approaches, but we do not know for certain whether such strategies reduce the incidence and severity of chronic lung disease. More importantly, no one has evaluated the potential consequences (e.g., increased respiratory acidosis, apnea and bradycardia, hemodynamic lability) of early extubation on long-term neurodevelopmental outcome. The more technology we are able to access the less certain we are how best to use it. Maybe in 25 years some of these issues will be clearly understood! MH.
Date: 16 Jun 2004
Time: 13:00:05
Of interest would be the following work done on 1998 that somehow went unnoticed
by most of us:
AIM To investigate the efficacy of nasal high frequency ventilation (nHFV) in
newborn infants with moderate respiratory insufficiency.
METHOD Twenty one preterm and term neonates were treated with nHFV for
respiratory insufficiency. Criteria for starting nHFV were: deterioration on
nasal CPAP expressed by a median pH of 7.24 and pCO2 of 8.3 kPa, or increasing
FIO2. nHFV was delivered using the Infant Star ventilator. Ventilator setting
amplitude was 35 cm H2O; mean airway pressure 7 cm H2O; and frequency 10 Hz.
RESULTS pCO2 decreased significantly from 8.3 kPa to 7.2 kPa after nHFV was
started. In five patients nHFV was discontinued after a median period of 61/2
hours due to CO2 retention and high oxygen need, and endotracheal mechanical
ventilation was started.
CONCLUSIONS nHFV can reduce pCO2 in neonates with moderate respiratory
insufficiency and, therefore, could be used to decrease the need for
endotracheal mechanical ventilation.
(Arch Dis Child Fetal Neonatal Ed 1998;79:61-63)
UserName: Eilon Shany
Institution: Soroka University Medical Center
telephone: +972-54-4613763
email: eshany@bgumail.bgu.ac.il
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