THE SAFETY AND EFFICACY OF AUTOMATED-WEANING FROM MECHANICAL VENTILATION FOLLOWING CARDIAC SURGERY

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Introduction: To determine the safety and efficacy of automatic weaning (AW), we compared adverse events associated with weaning by AW with conventional intermittent mandatory ventilation (IMV) in adult patients after cardiac surgery. Previously, in order to standardize weaning by eliminating clinician bias, we used an advanced algorithm for AW with volume-targeted variable pressure support and demonstrated significant reduction in time to extubation in patients undergoing coronary bypass. [1,2] Methods: Ninety eight patients undergoing elective surgical myocardial revascularization entered an IRB approved, randomized, prospective study comparing weaning from mechanical ventilation by an AW or by conventional IMV mode. Weaning for Group 1 was performed on a newly available mechanical ventilator, the Venturi (Cardiopulmonary Corporation, Milford, CT), employing an advanced algorithm for AW by volume-targeted variable pressure support. During apneic periods, the Venturi delivered the set tidal volume and rate by a volume control mode, whereas during spontaneous breathing, the ventilator automatically delivered 15 +/- 8 cm H2 O of pressure support to achieve a targeted tidal volume of 6-8cc/kg. Clinically stable patients with acceptable blood gases were eligible for extubation at pressure support levels < 7 cm H2 O. For Group 2, weaning was managed by the ICU team based on standard practice. Demographic and hemodynamic data, and ventilatory parameters were recorded. Adverse events were defined as serious (cardiopulmonary arrest and reintubation) and non-serious (PO2 < 60 mm Hg, PCO2 >55 mm Hg, and PH > 7.55). The incidence of non-serious events were derived from the total blood gas values obtained in each group. Continuous data are presented as mean +/- SD. Further analysis was performed using a Student's t-text and a p value <or=to0.05 was considered significant. Results: Consistent with our previous findings, the mean time to extubation was significantly reduced in the AW group (p<or=to0.05). The AW (N=48) and the IMV (N=50) groups had similar demographic and hemodynamic data and ventilatory parameters. There were no episodes of serious adverse events in either group. Non-serious adverse events are reported in Table 1 and were also clinically insignificant in both groups.Table 1Conclusion: Our results demonstrate that employing an automated weaning protocol is both safe and efficacious in patients following cardiac surgery.