The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

THE BENEFITS OF USING THE OPEN LUNG TOOL (OLT) WITH THE DIFFICULT TO OXYGENATE PATIENTS AS A LUNG RECRUITMENT MANUEVER AND AS A GUIDE TO SET OPTIMAL PEEP LEVELS

Suzana Ristoski RRT BBA MBA, Educator-Respiratory Care Department, Dr. Stephen Galens MD. Medical Director. William Beaumont Hospital, Troy, 44201 Dequindre Rd., Troy, MI 48085

Background: The OLT is an option on the Maquet Servo i ventilator. The OLT was available to the respiratory care staff, however initially rarely ever utilized secondary to the lack of knowledge and fear of the unknown. Initially, when the OLT was utilized and completed, Pressure Control (PC) was the ending mode of ventilation used, showing no significant improvement. In order to utilize this lung recruitment maneuver option effectively a trial protocol evaluation was performed. As a result of the positive findings of the observation and the data collection, a new protocol was developed. Certain criteria needed to be present in order to initiate the OLT. The initial criteria included a sustained FiO2 ≥ 50% and a PEEP level of ≥ 8 cmH2O. These patients often presented with ARDS or severe pneumonia. The time period for the trial was August 2005 through December 2005. Seven adult patients (pts) qualified for the OLT. These pts had the OLT performed and were closely observed and data was collected.

Method:
During the time frame of the trial, all pts that qualified for the OLT received an initial order from a pulmonologist to perform the OLT. The maneuver was performed by the respiratory therapist. Prior to starting the OLT: 1) the pt should be hemodynmically stable, 2) pt may have some sedation if agitated or has an increased RR, 3) therapist must suction pt; calculate ideal body weight for target tidal volume; observe initial dynamic compliance and mean airway pressure (MAP); and adjust alarms. General application of the OLT: 1) increase PEEP gradually to 20cmH2O, 2) increase PC to 30 cmH2O (PIP of 50cmH2O) -hold for 2 min, 3) decrease PC to target tidal volume, 4) decrease PEEP to closing critical pressure- add 2cmH2O to that pressure for optimal PEEP, 5) re-recruit the lung by returning the PIP to 50 cmH2O-hold for 2 min, 6) decrease PC to achieve the target tidal volume. After the OLT was performed the therapist had the autonomy to set ventilator settings according to what the OLT presented. The pt was set on BiVent unless otherwise ordered by the physician. ABGs were collected 1 hr after the OLT. Pt's dynamic compliance, ABG results, and hemodynamics were closely monitored. The OLT would be repeated every 8 hours (and as needed if pt deteriates) for the first 24 hrs. After the 24 hrs, pt was reassessed for the need of the OLT. As pt progresses they were weaned with the BiVent settings. BiVent was made the standard mode of ventilation for the protocol when the OLT is completed.

Results:
The ABG results of six out of the seven pts showed significant changes in PaO2 shown in Table 1. However there is one patient where the PaO2 decreased after the OLT- that patient was terminally weaned that day. Results showed that the ARDS patients showed a greater improvement in PaO2 compared to the severe pneumonia patients. Percent changes in PaO2 before and after, ranged from 366% to -28%. In addition, the BiVent mode showed better results compared to the use of PC observed prior to the protocol trial evaluation.

Table 1: PaO2 comparison before and after OLT maneuver

Patient 1 2 3 4 5 6 7
PaO2 Before OLT 88 62 65 63 89 92 61
PaO2 After OLT 218 97 303 75 148 66 171
% change post 1hr 147% 56% 366% 19% 66% -28% 180%

Conclusion: The OLT maneuver is utilized as a lung recruitment maneuver and for a guide to set the optimal PEEP and pressures to achieve the target tidal volume. It shows a significant improvement in oxygenation on hard to oxygenate pts. The study found that it is more effective with ARDS pts rather than with severe pneumonia pts, however improvements are still observed with the pneumonia pts. In addition, as lung mechanics change, vent settings must change as well.

Our OLT protocol gives the therapist the autonomy to change ventilator settings according to optimal settings that we have observed from the OLT maneuver.

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