Critical Care Medicine: June 2016 -
Volume 44 - Issue 6 - p 1098–1108
Bosma, K et al
Objectives:
Despite protocols incorporating spontaneous breathing trials, 31% of ICU
patients experience difficult or prolonged weaning from mechanical ventilation.
Nonfatiguing modes such as pressure support ventilation are recommended.
Proportional assist ventilation provides assistance in proportion to patient
effort, which may optimize weaning. However, it is not known how proportional
assist ventilation performs relative to pressure support ventilation over a
prolonged period in the complex ICU setting. The purpose of this study was to
compare the physiologic and clinical performance (failure rate), safety, and
feasibility of protocols using daily spontaneous breathing trial plus pressure
support ventilation versus proportional assist ventilation until ventilation
discontinuation. Design: Single-center, unblinded pilot randomized controlled
trial. Setting: Medical-surgical ICU of a tertiary-care hospital. Patients:
Adult patients intubated greater than 36 hours were randomized if they met
eligibility criteria for partial ventilatory support, tolerated pressure
support ventilation greater than or equal to 30 minutes, and either failed or
did not meet criteria for a spontaneous breathing trial. Interventions:
Patients were randomized to the pressure support ventilation or proportional
assist ventilation protocol (PAV+, Puritan Bennett 840; Covidien, Boulder, CO).
Both protocols used progressive decreases in level of assistance as tolerated,
coupled with daily assessment for spontaneous breathing trials. Measurements
and Main Results: Of 54 patients randomized, outcome data are available for 50
patients; 27 were randomized to receive proportional assist ventilation and 23
to receive pressure support ventilation. There were no adverse events linked to
the study interventions, and protocol violations were infrequent. Recruitment
was slower than projected (1.3 patients per month). The median (interquartile
range) time from randomization to successful extubation was 3.9 days (2.8–8.4
d) on proportional assist ventilation versus 4.9 days (2.9–26.3 d) on pressure
support ventilation (p = 0.39). Time to live ICU discharge was 7.3 days
(5.2–11.4 d) on proportional assist ventilation versus 12.4 days (7.5–30.8 d)
on pressure support ventilation (p = 0.03). Conclusion: This pilot study
demonstrates the utility, safety, and feasibility of the weaning protocols and
provides important information to guide the design of a future randomized
controlled trial comparing weaning from mechanical ventilation on pressure
support ventilation versus proportional assist ventilation.
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