In Support of Pressure Support

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Present generation mechanical ventilators are available with advanced microprocessor-based technology. Greater emphasis is being placed on the patient controlling the ventilator, rather than the physician controlling it. Pressure support ventilation (PSV) is a form of patient-triggered ventilation that supports spontaneous breathing during mechanical ventilation. It is flow-cycled, allowing the patient to determine the inspiratory time and rate. Each spontaneous breath is terminated when inspiratory flow decelerates to a predefined percentage of peak flow. At present, strict comparisons of the usefulness of PSV with other modalities of synchronized ventilation in newborns remain limited. This article reviews the principles and clinical applications of PSV for newborns who have respiratory failure.

Section snippets

Characteristics of pressure support ventilation

PSV is delivered to the mechanically ventilated patient during spontaneous breathing. It is a triggered mode, with changes in airway pressure or flow used as the trigger signal. Following detection of spontaneous patient effort, the ventilator delivers a breath that is flow cycled but time limited. As shown in Fig. 1, there is a sharp increase in inspiratory flow, which peaks and then decelerates rapidly. At the termination point, inspiratory flow ceases, and the breath cycles directly into

Pressure support ventilation: adult and pediatric experience

A commonly used ventilation modality in adults and children is volume-controlled ventilation. Addition of PSV, which is a switch to a pressure-targeted modality, has been shown to decrease the spontaneous work of breathing by partial or total unloading of respiratory muscles in adults and children.

Total unloading correlated well with levels of inspiratory assist, and when PSV was used at levels sufficient enough for total unloading of respiratory muscles it led to a muscle-resting effect

Pressure support ventilation: neonatal experience

Perhaps because of the relative novelty of PSV, little information has been published regarding its use in newborns. PSV has been used independently as a stand-alone mode in newborn infants and can be used in conjunction with other modalities of pressure-limited or volume-controlled synchronized ventilation.

Pressure support ventilation as a stand-alone mode

PSV is a flow-cycled but time-limited mode that supports each spontaneous breath just like A/C, and may be used in newborn infants as a stand-alone technique when reliable respiratory drive is present. Pressure support ventilation is patient-triggered, in that the inspiratory time, respiratory rate, and, to some extent, the minute ventilation remain under the control of the patient, thereby facilitating a natural pattern of breathing.

Patient-triggered ventilation has been shown to result in a

Pressure support ventilation during weaning

Successful weaning of the SIMV rate in preterm infants must be accompanied by an increase in spontaneous inspiratory effort to compensate for the reduction in mechanical support. Increased mechanical loads and poor spontaneous respiratory effort are common in preterm infants, however, and may delay the weaning process. The addition of PSV during weaning provides elastic unloading, averts diaphragmatic overexertion and fatigue, and facilitates the weaning process by alleviating some of the

Pressure support ventilation as an adjunct to synchronized intermittent mandatory ventilation

The high airway resistance of narrow endotracheal tubes and the added load imposed by triggering devices, combined with inconsistent spontaneous respiratory effort and mechanical disadvantages conferred by poor chest wall stability are common in preterm infants and can lead to small, ineffective spontaneous tidal volumes. The spontaneous breath tidal volumes may not be sufficiently large to maintain adequate alveolar ventilation and may represent just dead space ventilation [23]. The addition

Pressure support ventilation as an adjunct to volume-targeted synchronized intermittent mandatory ventilation

PSV seems to be an attractive adjunct to volume-controlled ventilation in infants who have reliable spontaneous respiratory drive. One such refinement is volume-assured pressure support, or VAPS, which incorporates inspiratory pressure support with conventional volume-assisted cycles. In this modality, the physician determines the pressure support level, peak flow, and a guaranteed tidal volume. If the patient demand is high relative to the peak flow and tidal volume settings, pressure

Summary

PSV, one of the newest ventilatory modes, provides an inspiratory pressure boost during spontaneous breathing to overcome the imposed work of breathing. Currently, RCTs comparing PSV with the newer synchronized ventilatory modes remain limited, but all available data indicate that PSV is safe and well tolerated even when used in premature extremely low birth weight newborn infants. Preliminary application of PSV to the neonatal population shows great promise. Applications include weaning during

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