Clinics in perinatology
-
Clinics in perinatology · Sep 2012
ReviewSynchronized mechanical ventilation using electrical activity of the diaphragm in neonates.
The electrical activity of the diaphragm (Edi) is measured by a specialized nasogastric/orogastric tube positioned in the esophagus at the level of the crural diaphragm. Neurally adjusted ventilatory assist (NAVA) uses the Edi signal as a neural trigger and intrabreath controller to synchronize mechanical ventilatory breaths with the patient's respiratory drive and to proportionally support the patient's respiratory efforts on a breath-by-breath basis. NAVA improves patient-ventilator interaction and synchrony even in the presence of large air leaks, and might therefore be an optimal option for noninvasive ventilation in neonates.
-
The photoplethysmogram (PPG) is a noninvasive circulatory signal related to the pulsatile volume in tissue and is displayed by many pulse oximeters. The PPG is similar in appearance to the invasive arterial waveform, but is noninvasive and ubiquitous in hospitals. There is increasing interest in seeking circulatory information from the PPG and developing techniques for a wide variety of novel applications. This article addresses the basic physics of photoplethysmography, physiologic principles behind pulse oximetry operation, and recent technological advances in the usefulness of the PPG waveform to assess microcirculation and intravascular fluid volume monitoring during intensive care.
-
Clinics in perinatology · Sep 2012
ReviewWhich continuous positive airway pressure system is best for the preterm infant with respiratory distress syndrome?
Various commercial and home-made continuous positive airway pressure (CPAP) systems are described in this article. CPAP may be delivered via a range of device-patient interfaces; nasal CPAP is most common, and short binasal prongs impose the least extrinsic load impedance on the infant. The source of pressure generation is categorized as either constant pressure or constant flow. The efficacy of different systems may vary according to whether lung volume recruitment, airway patency, minimization of work of breathing, or central nervous system stimulation are the primary goal of the clinical decision to use CPAP therapy.
-
Clinics in perinatology · Sep 2012
ReviewClinical effectiveness and safety of permissive hypercapnia.
Experimental and clinical data indicate that ventilator strategies with permissive hypercapnia may reduce lung injury by a variety of mechanisms. Seven randomized controlled trials in preterm neonates suggest that permissive hypercapnia started early, before the initiation of mechanical ventilation (in conjunction with continuous positive airway pressure), followed by prolonged permissive hypercapnia if mechanical ventilation is needed is an alternative to early ventilation and surfactant. Permissive hypercapnia may improve pulmonary outcomes and survival.
-
Clinics in perinatology · Sep 2012
ReviewControl of oxygenation during mechanical ventilation in the premature infant.
Maintenance of oxygen saturation targets is a demanding and tedious task because of the frequency with which oxygenation changes, especially in small infants receiving prolonged respiratory support. It is clear that the achievement of oxygenation targets can be improved by a higher nurse-to-patient ratio and by intense staff training. Automated control systems can also improve target maintenance, and this is achieved mainly by reducing exposure to hyperoxemia. The long-term benefits and safety of this strategy are yet to be determined in clinical trials.