摘要:

The cardiac and circulatory systems interact on many levels, including mechanical, neurologic, and neurohumoral. The mechanical interactions that are important for the failing heart include effects of intrathoracic pressure and lung volume on venous return and left ventricular function. Recent studies have been directed at exploring the role of mechanical ventilation, continuous positive airway pressure, and systolic gated increases in intrathoracic pressure as cardiac support modes. It appears that in the failing heart improved ventricular ejection predominates over decreased venous return and that both short-term and long-term improvement in cardiac function may be realized. It is also apparent that reflex control of the circulation is altered by respiratory maneuvers and that this may be as or more important than the mechanical effects.

ISSN:1070-5295    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Emphasis during mechanical ventilation of the most critically ill has focused in recent years on preventing further lung injury by the approach used to provide ventilatory support. Inverse ratio ventilation fits nicely into a lung protective ventilatory strategy since it emphasizes the use of pressure ventilation and the targeting of low peak alveolar pressure. However, no controlled, prospective data is available to support the superiority of inverse ratio ventilation regardless of target (pressure or volume) or actual inspiratory:expiratory (I:E) ratio when compared to conventional ratio ventilation. The current published data shows equivalence in gas exchange, hemody-namics and compliance regardless of approach used. Once positive end-expiratory pressure PEEP is set above the lower infection point on the pressure-volume curve of the lung, extending inspiratory time to increase mean airway pressure and oxygenation is a reasonable method of improving oxygenation provided auto-PEEP does not develop, since peak alveolar pressure is maintained constant. Emphasis should be on achieving an oxygenation target by increasing mean airway pressure not establishing a specific I:E ratio. In general most patients can be successfully managed with I:E ratios ⩽1:1.

ISSN:1070-5295    

出版商:OVID    

年代:1997

数据来源: OVID