Usefulness of continuous positive airway pressure in differential diagnosis of cardiac from pulmonary cyanosis in newborn infants

Persistent fetal circulation

Persistent fetal circulation (PFC), also known as persistent pulmonary hypertension of the newborn, is defined as postnatal persistence of right-to-left ductal or atrial shunting, or both in the presence of elevated right ventricular pressure. It is a relatively rare condition that is usually seen in newborns with respiratory distress syndrome, overwhelming sepsis, meconium and other aspiration syndromes, intrauterine hypoxia and ischemia, and/or neonatal hypoxia and ischemia. This condition causes severe hypoxemia, and, as a result, has significant morbidity and mortality. Improved antenatal and neonatal care; the use of surfactant; continuous monitoring of oxygenation, blood pressure and other vital functions; and early recognition and intervention have made this condition even more rare. In modern neonatal intensive care units, anticipation and early treatment of PFC and its complications in sick newborns are commonplace. Thus, severe forms of PFC are only seen on isolated occasions. Consequently, it is even more imperative to revisit PFC compared with the time when there were occasional cases of PFC seen in neonatal intensive care units, and to discuss evolving treatment and management issues that pertain to this syndrome.

Refractory neonatal hypoxemia: diagnostic evaluation and pharmacologic management

Hypoxemia refractory to oxygen administration and assisted ventilation is found in many clinical conditions and results from a variety of pathophysiologic disorders. Recent clinical and laboratory experience has demonstrated that the choice of therapy for an infant with refractory hypoxemia depends upon identification of the underlying etiologic and pathophysiologic conditions. The ideal therapies for many of these conditions have not yet been defined. We have provided, based on our experience, guidelines for selection of the most appropriate of the currently available therapies for many of these patients.

A practical approach to diagnosis and immediate care of the cyanotic neonate. Stabilization and preparation for transfer to level III nursery

The diagnostic and therapeutic strategies described above have been presented sequentially for the sake of clarity, but in practice should be performed as quickly as possible in any infant who remains cyanotic despite receiving 100% oxygen. The practitioner must proceed with emergent stabilization of the infant with specific therapies for identified problems and nonspecific therapies for suspected problems, recognizing that the coexistence of two or more pathophysiologic entities is not uncommon. By the time of transport, the practitioner may have laid the groundwork for further diagnostic procedures and therapies by having already classified the infant into one of four primary pathophysiologic categories, as outlined in Table 4. Although congenital heart disease may be highly suspected, confirmation may not be possible without echocardiography. The practitioner, however, should not be discouraged by failure to achieve a specific etiologic diagnosis, despite careful analysis of all the information obtained from diagnostic evaluations prior to transport. Hypoxemia refractory to oxygen administration and assisted ventilation is found in many clinical conditions and results from a variety of pathophysiological disorders. The pediatrician caring for such an infant has primary responsibility for stabilization and preparation for transport of the infant to a Level III facility, and for communicating information about diagnostic procedures and therapeutic maneuvers that might facilitate extended resuscitative efforts by the neonatologist accepting responsibility for the transport and subsequent care of the infant.

Influence of lipid infusion (0.4 g/kg/hr) and positive end expiratory pressure (8 cm H2O) on pulmonary function and hemodynamics in healthy anesthetized pigs

Fat emulsions are used increasingly for parenteral nutrition in premature infants suffering from various disorders, including respiratory insufficiency necessitating artificial ventilation with positive end expiratory pressure (PEEP). Both PEEP and lipid infusions (LI) may alter pulmonary hemodynamics. The simultaneous effect of LI and PEEP were therefore investigated. Five adult anesthetized Göttinger minipigs were infused with a 20% LI at a high rate of 0.4 g/kg/hr for 30 min, followed by PEEP of 8 cm H2O for 15 min. Catheters were inserted into the upper vena cava, the pulmonary artery, the right and left atrium, and the aorta, and pressures recorded continuously. Ventilation volume, respiratory fractional gas concentrations of O2 and CO2 (mass spectrometer), and blood gases were measured. The following parameters were calculated: total peripheral resistance, pulmonary arteriolar resistance, right-to-left shunt (QS/QT) dead space ventilation (VD/VT) and effective compliance. Total peripheral resistance remained unchanged. Pulmonary arteriolar resistance increased significantly during PEEP, PEEP + LI, but not during LI alone. QS/QT increased significantly during LI and returned to normal when PEEP was applied. VD/VT and effective compliance did not change during LI. The increased right to left shunt, caused by LI, is reduced by means of PEEP, while the pulmonary arteriolar resistance increased with PEEP and LI.

Continuous positive airway pressure: modes of action in relation to clinical applications

Some physical effects of CPAP are discussed, as are the various devices used for CPAP in infants. Some of the controversies about CPAP may be related to the unsuitability of certain techniques. Use in hyaline membrane disease, extrathoracic and intrathoracic airway obstruction, congestion of overperfusion of the lungs in diseases of the heart and great vessels, apnea repetens of immaturity, and phrenic nerve palsy is presented.