Use of high-frequency jet ventilation in neonates with hypoxemia refractory to high-frequency oscillatory ventilation

Respiratory management of established severe bronchopulmonary dysplasia

Respiratory management of infants with established severe BPD is difficult and there is little evidence upon which to base decisions. Nonetheless, the physiology of severe BPD is well described with a predominantly obstructive pattern. This pulmonary dysfunction results in prolonged exhalatory time constants and thus ventilator management must be focused on maintaining adequate oxygenation and ventilation through achieving full exhalation. This approach is often difficult to maintain in acute care settings and a culture of chronic care focused on slow change and steady progress is imperative. Once respiratory stability is achieved, the focus should shift to growth and development and avoidance of care practices and medications that impair neurodevelopment.

High-Frequency Jet Ventilation against Small-Volume Conventional Mechanical Ventilation in the Rabbit Models of Neonatal Acute Lung Injury

Patients with acute lung injury are ventilated by conventional mechanical ventilation (CMV) rather than high-frequency jet ventilation (HFJV). This study estimated the potential usefulness of HFJV in acute lung injury. The issue was addressed by comparing the effects on lung function of CMV and HFJV in two rabbit models of neonatal acute lung injury: repetitive saline lung lavage (LAV) and meconium aspiration syndrome (MAS) induced by intratracheal meconium instillation. The animals were then ventilated with either HFJV or CMV for 4 h. Ventilatory pressures, blood gases, and indexes of gas exchange were assessed. Lung edema formation was expressed as wet-dry lung weight ratio. Both LAV and MAS significantly decreased lung compliance, increased airway resistance, and caused severe hypoxemia, hypercarbia, and acidosis. Although CMV was superior to HFJV at 1 h of ventilation, there were no clinically relevant differences in lung function or edema formation between CMV and LAV in both models of respiratory insufficiency at 4 h of ventilation. We conclude that, HFJV may be used for ventilation in acute non-homogenous lung injury.

Understanding neonatal ventilation: strategies for decision making in the NICU

Neonatal ventilation is an integral component of care delivered in the neonatal unit. The aim of any ventilation strategy is to support the neonate's respiratory system during compromise while limiting any long-term damage to the lungs. Understanding the principles behind neonatal ventilation is essential so that health professionals caring for sick neonates and families have the necessary knowledge to understand best practice. Given the range of existing ventilation modes and parameters available, these require explanation and clarification in the context of current evidence. Many factors can influence clinical decision making on both an individual level and within the wider perspective of neonatal care.

Neonatal ventilatory techniques - which are best for infants born at term?

Few studies have examined ventilatory modes exclusively in infants born at term. Synchronous intermittent mandatory ventilation (SIMV) compared to intermittent mandatory ventilation (IMV) is associated with a shorter duration of ventilation. The limited data on pressure support, volume targeted ventilation and neurally adjusted ventilatory assist demonstrate only short term benefits in term born infants. Favourable results of high-frequency oscillatory ventilation (HFOV) in infants with severe respiratory failure were not confirmed in the two randomised trials. Nitric oxide (NO) in term born infants, except in those with congenital diaphragmatic hernia (CDH), reduces the combined outcome of death and requirement for extracorporeal membrane oxygenation (ECMO). In infants with severe refractory hypoxaemic respiratory failure, ECMO, except in infants with CDH, reduced mortality and the combined outcome of death and severe disability at long-term follow-up. Randomised studies with long term outcomes are required to determine the optimum modes of ventilation in term born infants.

Neonatal ventilators: how do they differ?

Remarkable technological advances over the past two decades have brought dramatic changes to the neonatal intensive care unit. Microprocessor-based mechanical ventilation has replaced time-cycled, pressure-limited, intermittent mandatory ventilation with almost limitless options for the management of respiratory failure in the prematurely born infant. Unfortunately, much of the infusion of technology occurred before the establishment of a convincing evidence base. This review focuses on the basic principles of mechanical ventilation, nomenclature and the characteristics of both conventional and high-frequency devices.

Neonatal pulmonary hypertension treated with inhaled nitric oxide and high-frequency ventilation

Term and near-term infants with pulmonary hypertension are frequently treated with inhaled nitric oxide. This therapy can be delivered with high-frequency ventilation, but there has been limited study of the relative effectiveness of high-frequency jet ventilation and high-frequency oscillatory ventilation.

OBJECTIVE

To compare short-term clinical outcomes of neonates with pulmonary hypertension treated with inhaled nitric oxide plus either high-frequency jet ventilation or high-frequency oscillatory ventilation.

STUDY DESIGN

Study infants met the following criteria: >or=35 weeks gestation, respiratory failure with pulmonary hypertension, no congenital malformations and treatment in the first week of life with inhaled nitric oxide plus either high-frequency jet ventilation (n=22) or high-frequency oscillatory ventilation (n=43). Data were collected from medical records.

RESULT

The jet ventilation and oscillatory ventilation groups were similar in terms of gestational age, but the jet ventilation group had less severe respiratory illness (that is, lower oxygenation index) just prior to initiation of the combination of nitric oxide and high-frequency ventilation. The jet ventilation group spent more hours on inhaled nitric oxide (71.4 versus 40.8; P=0.004) but was less likely to require extracorporeal membrane oxygenation (2(9%) versus 19(44%); P=0.004). No difference was found in the ages at which oxygen and high-frequency ventilation were discontinued.

CONCLUSION

Term and near-term neonates with pulmonary hypertension who require nitric oxide have similar short-term outcomes regardless of whether nitric oxide is delivered by high-frequency jet ventilation or high-frequency oscillatory ventilation.