SESSION TITLE: Ventilatory Strategies in Severe Hypoxemia
SESSION TYPE: Original Investigation Slide
PRESENTED ON: Wednesday, October 30, 2013 at 07:30 AM - 09:00 AM
PURPOSE: Severely obese patients are often difficult to wean from mechanical ventilation (MV) due to low compliance. High positive end expiratory pressure (PEEP) is needed to recruit alveoli. To set an optimal PEEP, obese patients who failed weaning in an initial attempt were randomized to one of two methods to set PEEP in this trial. We aim to determine which method is superior in weaning patients by day 30 after starting the protocol.
METHODS: This is a single center, randomized, prospective, controlled study of very obese patients (BMI>40) who required tracheostomy for prolonged weaning. All patients were hemodynamically stable on pressure support ventilation with FIO2 less than 0.6. Patients were randomly assigned to one of two protocols for setting PEEP. In one group, PEEP was set based on the improvement in C stat (compliance measurement on Hamilton ventilator). In the other group, transpulmonary pressure was measured with an esophageal balloon-monitoring device (EPMD), and PEEP was set to keep transpulmonary pressure positive (0-10 cmHg). We also compared the outcomes for this entire cohort to a historic control group of patients with similar baseline characteristics, where PEEP was set by conventional weaning protocol.
RESULTS: Preliminary data of 24 patients randomly assigned to set PEEP by Cstat or EPMD did not demonstrate a significant difference in success of weaning from MV at day 30 (Cstat 81.8% vs EPMD 69.2%). Of the patients who were weaned by day 30, however, the mean days to wean were less in the EPMD arm vs the Cstat arm (5.9 days vs 11.9 days P<0.015). When the success of weaning at day 30 in the entire cohort of the 24 study patients was compared with 24 similar historic controls, the study patients had a higher success of weaning at day 30 (75% vs 62.5% ). The set PEEP was higher in the study patients compared to historical controls (25.3 cmHg vs 9.0 cmHg, p<0.0001). None of the study subjects had pneumothorax or hemodynamic compromise.
CONCLUSIONS: Whether PEEP is set by Cstat or EPMD does not have a significant impact in weaning obese patients. The high PEEP used in both methods did not have adverse consequences. Compared to historic controls, in which lower PEEP was used, we observed improvement in weaning outcomes using higher PEEP.
CLINICAL IMPLICATIONS: We believe that high pleural pressures in obese patients cause atelectasis, and using higher PEEP opens alveoli and leads to higher success in weaning
DISCLOSURE: The following authors have nothing to disclose: Zuheir Kassabo, Robert Shaw, Charles Bangley, Patricia Rice, Khalid Saadah, Mark Mazer
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