2004 OPEN FORUM Abstracts
TEMPORARY APPLICATION OF Bi-LEVEL MODE VENTILATION TO RE-EXPAND COLLAPSED LUNG UNITS WITH APPROPRIATE POSITIVE END EXPIRATORY PRESSURE (PEEP) TITRATION DURING LOW TIDAL VOLUME VENTILATION IS SAFE AND EFFECTIVE.
Andrew Hrehocik, RRT, Mark
Cohen, RRT, Edgar Delgado, RRT, Ray Tuttle, RRT, Kevin Springer, RRT,
Michael Donahoe, MD. Departments of Respiratory Care and Pulmonary/Critical Care
Medicine. University of Pittsburgh Medical
Center, Pittsburgh, PA.
INTRODUCTION:
Derecruitment of the lungs may occur during low tidal volume
ventilation. In order to prevent/reverse derecruitment, minimal lung
opening pressure should be determined. A lung recruitment protocol
was developed to determine the lung opening pressure, followed by
titration of PEEP to prevent derecruitment. Safety and efficacy of
procedure was evaluated for quality improvement purposes.
During
the ARDS-net low tidal ventilation clinical trial, different lung
recruitment maneuver was proposed, but not implemented due to safety
concerns. The
setting was a large tertiary medical center with 14 ICUs, a census of
90 ventilators/day, and 132 Respiratory Care staff.
METHOD: To find minimal
opening pressure (First Attempt), Bi-level mode was
adjusted with I:E ratio of 2:1, HIGH
PEEP level of 40 cmH2O and set RR, FiO2
and PEEP same as A/C mode. Bi-Level mode ventilation was implemented
for 20 seconds or patient limit (i.e. SpO2 ≤
85%, cardiac arrhythmia, and hypotension), then Return
to the A/C mode. If SpO2 and static compliance (Cst
) improved after 3 to 5 minute, lungs opening pressure
was achieved. However if SpO2 and Cst
did not improve, the procedure was repeated with HIGH PEEP setting
increased to 45 cmH2O. If no improvement at 45 cmH2O,
then HIGH PEEP was
increased to 50 cmH2O. If HIGH
PEEP level of 50 cmH2O was inadequate, physician
direction was needed for further increases. If derecruitment
occurred, post recruitment procedure, PEEP (on A/C mode) was
increased by 2.0 cmH2O and recruitment re-attempted with
known opening pressure until the SpO2 was maintained at ≥
90%.
SAFETY ASSESSMENT: Continuous
monitoring of oxygen saturation via pulse oximetry, arterial blood
pressure and heart rate was assessed for safety during the procedure.
Desaturation was defined as SpO2
< 85%,
Hypotension as MAP
< 60 mmHg, Bradycardia as HR
<
60 bpm and Tachycardia as HR
> 120 bpm.
RESULTS:
QI survey of 18 patients revealed successful recruitment.
Mean Cst increased by 9.79
cmH2O (25.71 to 35.5) (t-test: paired two sample for
means) post recruitment. SpO2 increased 8.78% (86.07 to
94.86) (t-test: paired two sample for means) post recruitment
procedure. Patient population revealed that 55.6% (10) had sepsis
induced ARDS, 16.6% (3) had aspiration pneumonia induced ARDS and
27.8% (5) had atelectasis. Initial recruitment effect for Pneumonia
induced ARDS lasted 10+4 hours, sepsis induced ARDS 14+4
hours and Atelectasis 24+2 hours. Among patients having
recruitment procedure, 16.6% (3) developed tachycardia, and 5.5% (1)
developed hypotension. These adverse effects were transient and
resolved when patients were reverted back to the A/C mode.
Furthermore, it was not uncommon to witness a drop in SpO2
during the recruitment process; this is usually accompanied with a
rise to a level greater than baseline when the patient is immediately
reverted back to the A/C mode.
CONCLUSION: Application of
Bi-Level ventilation for lung recruitment is safe and effective.
Respiratory therapists can implement this simple and
effective recruitment method in ICU settings when requested by an
attending physician.