Ventilation practices and critical events during transport of ventilated patients outside of hospital: a retrospective cohort study.
BACKGROUND
Little is known about mechanical ventilation practices during patient transport outside of hospital in the civilian setting, although these practices may have clinical impact. Objective. We set out to describe ventilation practice, the use of lung-protective ventilation strategies, administration of sedation and neuromuscular blockade, and related critical events during out-of-hospital transport of ventilated patients.


METHODS
We conducted a population-based retrospective cohort study. Ventilator, pharmacy, and clinical data were extracted from the database of the provincial transport medicine agency in Ontario, Canada. Patients at risk for acute lung injury were identified by explicit screening criteria and lung-protective ventilation was assessed according to evidence-based thresholds. Critical events occurring during transport consisting of clinical deterioration or resuscitative procedures were recorded. RESULTS. We identified 1,735 mechanically ventilated adults who received out-of-hospital transport. Volume control and pressure control were the most commonly used ventilation modes. The median tidal volume delivered during transport was 500 mL (interquartile range 450-600) with positive end-expiratory pressure (PEEP) of 5 cmH(2)O (5-7) and peak inspiratory pressure of 24 cmH(2)O (20-29). Most patients (92%) were ventilated with peak pressures < or = 35 cmH(2)O; 22% of patients were ventilated with PEEP < 5 cmH(2)O. Ventilation in patients at risk of acute lung injury was not significantly different, and 68% of this subgroup was ventilated within lung-protective thresholds. Sedation was administered in 1,235 transports (71.2%) with frequent repeat administration. Neuromuscular blockade was administered in 385 transports (22.2%). Critical events occurred during 297 (17.1%) transports, due primarily to new-onset hypotension (n = 208). New in-transit hypotension was independently associated with sedative administration.


CONCLUSIONS
In-transit mechanical ventilation practices are variable, although patient exposure to potentially injurious pressures and volumes is uncommon. The application of PEEP is modest. In-transit hypotension is common and associated with sedative administration. The extent to which these practices impact patient outcome is unclear.
Singh
Jeffrey M
JM
Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada. jeff.singh@uhn.on.ca
Ferguson
Niall D
ND
MacDonald
Russell D
RD
Stewart
Thomas E
TE
Schull
Michael J
MJ
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019148:Neuromuscular Blockade / Q000706:statistics & numerical data; D009864:Ontario; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000706:statistics & numerical data; D012189:Retrospective Studies; D014187:Transportation of Patients