Pressure-support ventilation (PSV) is a form of important ventilation mode. Patient-ventilator synchrony of pressure support ventilation can be divided into inspiration-triggered and expiration-triggered ones. Whether the ventilator can track the patient's inspiration and expiration very well or not is an important evaluating item of the performance of the ventilator. The ventilator should response to the patient's inspiration effort on time and deliver the air flow to the patient under various conditions, such as different patient's lung types and inspiration effort, etc. Similarly, the ventilator should be able to response to the patient's expiration action, and to decrease the patient lung's internal pressure rapidly. Using the Active Servo Lung (ASL5000) respiratory simulation system, we evaluated the spontaneous breathing of PSV mode on E5, Servo i and Evital XL. The following parameters, the delay time before flow to the patient starts once the trigger variable signaling the start of inspiration, the lowest inspiratory airway pressure generated prior to the initiation of PSV, etc. were measured.
Exhalation ; Humans ; Inhalation ; Interactive Ventilatory Support ; Lung ; physiology ; Pressure ; Ventilators, Mechanical

Mechanical ventilation has, since its introduction into clinical practice, undergone a major evolution from controlled ventilation to diverse modes of assisted ventilation. Conventional mechanical ventilators depend on flow sensors and pneumatic pressure and controllers to complete the respiratory cycle. Neurally adjusted ventilatory assist (NAVA) is a new form of assisted ventilation in recent years, which monitors the electrical activity of the diaphragm (EAdi) to provide an appropriately level of pressure support. And EAdi is the best available signal to sense central respiratory drive and trigger ventilatory assist. Unlike other ventilation modes, NAVA breathing instructions come from the center. Therefore, NAVA have the synchronous nature of the breaths and the patient-adjusted nature of the support. Compared with traditional ventilation mode, NAVA can efficiently unload respiratory muscles, relieve the risk of ventilator-induced lung injury (VILI), improve patient-ventilator coordination, enhance gas exchange, increase the success rate of weaning, etc. This article reviews the research progress of NAVA in order to provide theoretical guidance for clinical applications.
Humans ; Interactive Ventilatory Support ; Respiration, Artificial ; Positive-Pressure Respiration ; Diaphragm/physiology* ; Respiratory Muscles/physiology*

Despite of the development of neonatal medicine, ventilator induced lung injury has remained as one of the unsolved problems in preterm infants. Recently new modalities and modes of ventilation have been developed and used in clinical setting in neonatal intensive care units. These include non invasive ventilation which does not need endotracheal intubation, volume targeted pressure support ventilation, and proportional assist ventilation. This review describes these new techniques and their clinical usefulness in NICU.
Humans ; Infant ; Infant, Newborn ; Infant, Premature ; Intensive Care Units, Neonatal ; Interactive Ventilatory Support ; Intermittent Positive-Pressure Ventilation ; Intubation, Intratracheal ; Noninvasive Ventilation ; Positive-Pressure Respiration ; Respiration ; Ventilation ; Ventilator-Induced Lung Injury

OBJECTIVETo understand the effect of lung recruitment maneuver (LRM) with positive end-expiratory pressure (PEEP) on oxygenation and outcomes in preterm infants with respiratory distress syndrome (RDS) ventilated by proportional assist ventilation (PAV).

METHODFrom January 2012 to June 2013, thirty neonates with a diagnosis of RDS who required mechanical ventilation were divided randomly into LRM group (n=15, received an LRM and surport by PAV) and control group (n=15, only surport by PAV). There were no statistically significant differences in female (7 vs. 6); gestational age [(29.3±1.2) vs. (29.5±1.1) weeks]; body weight[(1,319±97) vs. (1,295±85) g]; Silverman Anderson(SA) score for babies at start of ventilation (7.3±1.2 vs. 6.9±1.4); initial FiO2 (0.54±0.12 vs. 0.50±0.10) between the two groups (all P>0.05). LRM entailed increments of 0.2 cmH2O (1 cmH2O=0.098 kPa) PEEP every 5 minutes, until fraction of inspired oxygen (FiO2)=0.25. Then PEEP was reduced and the lung volume was set on the deflation limb of the pressure/volume curve.When saturation of peripheral oxygen fell and FiO2 rose, we reincremented PEEP until SpO2 became stable. The related clinical indicators of the two group were observed.

RESULTThe doses of surfactant administered (1.1±0.3 vs. 1.5±0.5, P=0.027), Lowest FiO2 (0.29±0.05 vs. 0.39±0.06, P=0.000), time to lowest FiO2[ (103±18) vs. (368±138) min, P=0.000] and O2 dependency [(7.6±1.0) vs.( 8.8±1.3) days, P=0.021] in LRM group were lower than that in control group (all P<0.05). The maximum PEEP during the first 12 hours of life [(8.4±0.8) vs. (6.8±0.8) cmH2O, P=0.000] in LRM group were higher than that in control group (P<0.05). FiO2 levels progressively decreased (F=35.681, P=0.000) and a/AO2 Gradually increased (F=37.654, P=0.000). No adverse events and no significant differences in the outcomes were observed.

CONCLUSIONLRM can reduce the doses of pulmonary surfactant administered, time of the respiratory support and the oxygen therapy in preterm children with RDS.

Female ; Humans ; Infant, Newborn ; Infant, Premature ; Interactive Ventilatory Support ; methods ; Lung ; physiopathology ; Male ; Oxygen ; administration & dosage ; Oxygen Inhalation Therapy ; Positive-Pressure Respiration ; methods ; Pulmonary Surfactants ; administration & dosage ; Respiration ; Respiration, Artificial ; Respiratory Distress Syndrome, Newborn ; physiopathology ; therapy ; Tidal Volume ; Treatment Outcome