2001 OPEN FORUM Abstracts
CASEREPORT: USE OF BILEVEL VENTILATION TO MAINTAIN OXYGENATION AND IMPROVE CO2CLEARANCE WHILE TRANSITIONING FROM PCV TO PSV
Jeff Lantz BS, RRT, LouisianaState University Health Sciences Center, Shreveport, LA
Introduction: BiLevelTM(Mallinckrodt PB 840) is a pressure based mode of ventilation that allows unrestrictedspontaneous breathing at any point in the mechanical ventilation cycle. It hasalso been described as a mode in which the patient is allowed to breath spontaneouslyat two levels of PEEP. In the absence of spontaneous breathing, Bilevel producesa mechanical breath cycle identical to pressure control ventilation (PCV). Benefitsof BiLevel include the ability to deliver a pressure based ventilation strategywith improved patient-ventilator synchrony and a decreased need for sedation.
Case Summary: A30 year-old male was admitted to our trauma unit following a motor vehicle accidentwith chest trauma and subsequent development of ARDS. A lung protective strategyof low-frequency PCV1 was used to support oxygenation while acceptinghypercapnea. As the patient?s lung injury gradually improved, attempts to transitionfrom PCV to pressure support ventilation (PSV) yielded improved CO2clearance yet decreased PaO2/FiO2 ratio. The PB 840 ventilatorwas initiated with BiLevel to allow spontaneous breathing while maintaininga pressure based ventilation strategy. Oxygenation was maintained and even improvedwith the use of BiLevel. Minute ventilation, and thus CO2 clearancewas augmented with the capability of the patient to superimpose spontaneous,pressure supported breathing. This also allowed the use of lower ventilationpressures for the ventilator mandated breaths. As the patient?s lung injurycontinued to improve, ventilation pressures were further weaned and transitionto PSV was well tolerated with eventual removal from ventilatory support.
Discussion: Theadvantages of BiLevel in this patient were the ability to maintain a lengthyinspiratory time (1:1 ratio) for the ventilator mandated breaths while allowingpressure supported spontaneous breathing at any point in the mechanical ventilationcycle. This strategy maintained oxygenation while allowing spontaneous breathingto augment CO2 clearance.
1.Conrad, SA. Advances in the Management of Respiratory Failure ? Advanced Strategiesfor Mechanical Ventilation in Severe Acute Respiratory Failure. ASAIO Journal1996;42(3):204-206.