A seven-year international, multi-centre clinical trial led by London Health Sciences Centre Research Institute (LHSCRI) and St. Michael’s Hospital, a site of Unity Health Toronto, has found that a new ventilation mode called proportional assist ventilation (PAV+™) could improve outcomes for patients in the intensive care unit (ICU) who require help breathing. The study is published in the New England Journal of Medicine.
When patients need ventilation to support breathing, critical care physicians have the choice of using different modes on ventilator machines. This includes a standard mode called pressure support ventilation (PSV) that is available on most ventilators and provides the same level of breathing assistance at all times, as well as a newer mode called proportional assist ventilation (PAV+TM) that adjusts the level of breathing support based on the patient’s needs.
“PAV+TM is a newer mode of ventilation that personalizes ventilation support to each patient,” says Dr. Karen Bosma, Scientist at LHSCRI, Physician at London Health Science Centre (LHSC), and Associate Professor of Medicine at Western University. “The goal of this study was to compare PAV+TM to the more common mode, PSV, and determine if PAV+TM leads to a decrease in the length of time a patient requires ventilation.”
While the study did not find a significant difference in the length of time patients remained on ventilation between the two modes, it did reveal meaningful benefits associated with PAV+. Patients in the PAV+ group came off sedation at a faster rate while on mechanical ventilation, and had fewer days of delirium during the trial. This is an important finding, as patients who experience prolonged sedation and delirium while in the ICU are at greater risk of experiencing psychological and cognitive problems long-term.
The study enrolled 722 patients, including patients from LHSC and St. Michael’s Hospital. Of those, 573 were randomly assigned to either PAV+TM or PSV mode of ventilation and were included in the analysis. The median time spent on mechanical ventilation was 7.3 days in the PAV+TM group and 6.8 days in the PSV group. In addition, patients were checked daily for signs of delirium. In the group using PAV+TM, delirium was seen in about 23 per cent of the days patients were assessed, compared to 26 per cent in the PSV group. The study also found that, over the course of the patient’s treatment on the ventilator, the use of sedative drugs was reduced at a faster rate in patients in the PAV+ group.
“Even small advances that improve patient wellbeing during and after an ICU stay are highly valuable,” says Dr. Laurent Brochard, clinician-scientist at St. Michael’s Hospital. “This is what we found here and we want to continue exploring this approach, which only requires adjusting ventilator settings.”
Looking ahead, the researchers note they plan to use the data from this trial to conduct additional studies.
“This is one of the largest ventilation studies to date examining these two modes of ventilation, and over the last seven years we have gathered a lot of crucial data on critically ill patients on a ventilator,” says Dr. Bosma. “Future research will use artificial intelligence to analyze this data helping us better understand PAV+TM and how it may minimize specific health consequences associated with prolonged ventilation.”