Comparison of different rates of artificial ventilation for preterm infants ventilated beyond the first week of life

Matching ventilatory support strategies to respiratory pathophysiology

Neonates can suffer from various diseases that impact differently on lung function according to the specific pulmonary pathophysiology. As a consequence, the optimal respiratory support will vary according to disorder. Most randomized trials have only included prematurely born infants who have respiratory distress syndrome (RDS) or infants who have severe respiratory failure. Meta-analysis of the results has demonstrated that for the prematurely born infant who has RDS, prophylactic high-frequency oscillatory ventilation only results in a modest reduction in bronchopulmonary dysplasia, and patient-triggered ventilation (assist/control or synchronized intermittent mandatory ventilation) reduces the duration of ventilation if started in the recovery phase. Whether the newer triggered modes are more efficacious remains to be appropriately tested. In term infants who have severe respiratory failure, extracorporeal membrane oxygenation increases survival, but inhaled nitric oxide only reduces the need for extracorporeal membrane oxygenation. Research is required to identify the optimum respiratory strategy for infants who have other respiratory disorders, particularly bronchopulmonary dysplasia.

Optimal strategies for newborn ventilation--a synthesis of the evidence

A variety of ventilation modes are available for the newborn. Although, there have been randomised trials assessing certain modes, these have generally only included prematurely born infants with RDS or infants with severe respiratory failure. Meta-analysis of the results of those trials has demonstrated that neither patient triggered nor high frequency oscillatory ventilation is advantageous for the prematurely born infant with RDS, but extracorporeal membrane oxygenation increases survival in infants with severe respiratory failure. Appropriately designed studies are required to determine the role of newer ventilation modes and whether forms of respiratory support avoiding intubation are less injurious to the lungs. Research should also focus on infants with other respiratory disorders, particularly BPD. Prior to further randomised trials being undertaken, it is essential that the optimum method of applying each ventilator mode is identified and it is clearly understood whether differences in ventilator/oscillator performance influence outcome.

Update on modalities of mechanical ventilators

Recent advances in ventilator technology have often not been confirmed by randomised trials and instead serious shortcomings have been highlighted. Ventilation modes should only be introduced into routine clinical practice when proved efficacious in appropriately designed studies and no adverse outcomes identified by long term follow up.

Inspiratory and expiratory times for infants ventilator-dependent beyond the first week

The aim of this study was to determine optimum inspiratory and expiratory times to be used for ventilation of infants older than one week of age. Each infant was studied at a rate of 30 breaths/min (inspiratory times (TI) of 1.0, 0.67 and 0.5 s with expiratory times (TE) of 1.0, 1.33 and 1.5 s, respectively) and at a rate of 60 breaths/min (TI 0.5, 0.33 and 0.25 s and TE 0.5, 0.67 and 0.75 s, respectively). Arterial blood-gases were examined after 20 min on each setting. Fifteen infants with a median gestational age of 27 weeks were studied at a median postnatal age of 9 days and 10 infants with a median gestational age of 27 weeks at a median postnatal age of 24 days. All infants had type I chronic lung disease. Oxygenation did not consistently improve as TI was prolonged, elevating mean airway pressure but, particularly in older infants, was better at TI > or = 0.5 s compared with TI < 0.5 s. In both groups, carbon dioxide elimination was better at 60 than at 30 breaths/min. Thus we suggest that in infants fully ventilator-dependent beyond the first week of life, an inspiratory and expiratory time of 0.5 s should be used as the first choice.