2001 OPEN FORUM Abstracts
New Method of Fast-Track Weaning of Post-Open Heart Patient Using the Siemens Servo 300A in PRVC with Automode
Mark Rose, RRT,Mike Trevino, RRT, Sharon Trongaard, RRT, Gary Weinstein, MD, Presbyterian Hospitalof Dallas.
Introduction: PressureRegulated Volume Control (PRVC) in conjunction with Automode is a ventilationapplication available on the Servo 300a. PRVC is a time cycled, pressure limited,control mode that will deliver a preset target volume by automatically varyingthe inspiratory pressure control level according to the mechanical propertiesof the lung/thorax. Automode is an adjunct to PRVC that allows the ventilatorto switch back and forth between a machine established rate and a patient establishedspontaneous rate (Support). The application of this ventilator strategy maybe beneficial in effectively and efficiently liberating patients from the ventilator.The following case summary highlights the benefits of this application in apostoperative cardiac surgery patient.
Case Summary: Afterhaving a Ross procedure in the usual fashion under standard general anesthesia,a 55-year-old male with a history of aortic insufficiency and stenosis was placedon the Servo 300a in the PRVC mode with the Automode on. Ventilator settingswere as follows; f:10, Vt:900cc, FiO2:.70, PEEP:5cwp. Our extubation criteriawere; spontaneous RR < 25bpm, spontaneous Vt >300cc, FiO2 <.50, PEEP<6cwp, Pressure Support <13cwp, and ETCO2 within 15 mm Hg of baseline.An initial ABG was drawn after 20 minutes and correlated with the ETCO2 andSaO2 monitors. Appropriate changes were made at this time, adjusting rate andFiO2 to achieve normal blood gas parameters. After spontaneous respirationswere noted, the Automode/Support adjunct was utilized. The patient?s lung mechanicswere evaluated and hemodynamic stability was verified with the RN. The FVC was> 10ml/kg of IBW and MIP was > -20cwp. The set Vt was reset to 300cc.After 30 minutes, an ABG was drawn and found to be acceptable. The patient wasthen extubated without difficulty.
Results: ANovember 1998 publication from the Cardiology Roundtable presented a FACT BRIEFtitled ?National Benchmark Information Regarding Post-Open Heart VentilationWeaning?. The identified benchmark was 6-8 hours with outliers defined as ventilatortime greater than 12 hours for comparable hospitals to our own. Our facilitybenchmark, based on 587 cases in fiscal year 2000, reflected a mean of 8.4,a median of 7, and a mode of 5 hours respectively. As the table below reflects,this patient was well below both benchmark targets.
|Total time on pump in theOR||Total time on ventilator||Average Weaning Time|
|181 minutes||3 hours||45 minutes|
In conclusion,and for this patient, PRVC in conjunction with Automode was an effective tool,capable of utilizing less therapist time while still effectively and quicklyliberating patients from the ventilator. Further, more controlled studies arewarranted to evaluate the long-term effectiveness of this promising approachto weaning ventilated post-operative open-heart patients.