Ventilation and Weaning Practices in Australia and New Zealand

Abstract

Using a one-day prospective point prevalence design, this study aimed to characterise the current practice of mechanical ventilation and weaning in Australian and New Zealand intensive care units. During 2005, a bi-national one-day survey of 55 intensive care units found the point-prevalence of mechanical ventilation to be 284/491(58%). Common modes used were synchronised intermittent mandatory ventilation with pressure support, pressure support ventilation (each 116/284, 41%) and pressure-control modes (48/284, 17%). Relative to volume-control modes, pressure-control was more frequently used for patients with respiratory disease (odds ratio 4.7, 95% confidence interval 2.4 to 9.2, P <0.001) or greater severity of illness (odds ratio 1.7, 95% confidence interval 1.1 to 2.6, P=0.01, per five-point increment in the maximum sequential organ failure score). Excluding cardiothoracic surgery patients, the Kaplan-Meier estimated median total ventilation duration was 1.9 days (interquartile range 0.8 to 6.8 days). Apart from 24/255 (9.4%) patients who received only pressure support ventilation, weaning methods (attempted in 255 patients, 29 prior deaths) included: change to pressure support ventilation (186/255, 73%), T-piece (31/255, 12%) or other methods (14/255, 5.5%). The point prevalence of mechanical ventilation was greater than comparable international studies. Australian and New Zealand intensive care unit ventilatory practices are similar, but differ substantially from published international survey results, due to a near absence of assist/control, prominent use of pressure-control modes and a preference for pressure support ventilation weaning as opposed to T-piece.

Neurally adjusted ventilatory assist improves patient–ventilator interaction

“…There has been a trend over the years towards use of ventilatory modes in which some degree of spontaneous respiratory activity is preserved, known as partial ventilator assist [4,5]. These modes have been shown to reduce the adverse effects of prolonged sedation [6][7][8], neuropathy associated with use of neuromuscular blocking agents [9,10], and ventilatorinduced diaphragmatic dysfunction [11][12][13], while also improving gas exchange [14].…”

“…The most often used partial ventilatory assist mode is pressure support (PS) [4,5]. PS is often well tolerated, but the difference between the ventilatory profiles of the patient and the ventilator can lead to patient-ventilator asynchrony [15][16][17].…”

Arterial oxygen tension and mortality in mechanically ventilated patients

“…Mechanical ventilation is a life-saving intervention commonly applied to critically ill patients admitted to the intensive care units (ICUs) [1,2]. Most of these patients require a higher than normal fraction of inspired oxygen (FiO 2 ) in order to maintain an adequate arterial oxygen tension (PaO 2 ).…”

Use of invasive mechanical ventilation in Australian emergency departments

“…12,13,19 Other clinician-selected settings were similar to those reported in a recent 1 day prevalence study of mechanical ventilation across Australian and New Zealand ICU. 11 The mean recorded tidal volume was 8 mL/kg, which is within the range (6 to 8 mL/kg) believed to avoid iatrogenic damage to alveoli. 20 Lung protective ventilation using low tidal volumes and plateau pressures below 30 cmH2O has been demonstrated to reduce mortality in patients with acute lung injury and ARDS.…”

“…Data collection forms were modified for use in the ED from those used in a prior study examining mechanical ventilation practices across ICUs in Australia and New Zealand. 11 Forms were then sent to medical and nursing ED clinicians with expertise in mechanical ventilation to assess clinical sensibility. Once modified, the forms were piloted in 20 patients at the ED of St Vincent's Hospital Victoria to determine usability of the form and feasibility of data collection.…”