The Science Journal of the American Association for Respiratory Care

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.

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