2006 OPEN FORUM Abstracts
CASE STUDY: USING VOLUMETRIC CAPNOGRAPHY (VCO2) TO AID IN THE WEANING OF INHALED NITRIC OXIDE (INO) IN A CRITICALLY ILL INFANT
Sandra Rumer AS,
RRT, Betty L. Blake BS,
RRT, NPS, Susan Aucott, MD, The Johns
Hopkins Hospital, Baltimore, Maryland
INTRODUCTION: Monitoring, and managing Infants with PPHN can be very problematic as it is critical to understand what is dynamically occurring at the pulmonary capillary interface. Pulse oximetry (SpO2) can also be limiting because these patients are often hyper oxygenated to facilitate the decrease of pulmonary vascular resistance. An Infants SpO2 will not decrease below 100% until the arterial oxygenation (PaO2) decreases to ~58 torr due to the presence fetal hemoglobin. This delay can make titrating Nitric Oxide to therapeutic levels difficult. The NICO monitor measures volumetric carbon dioxide (VCO2), and MValv (alveolar minute ventilation). VCO2 has been shown to be a sensitive indicator of pulmonary blood flow when measured in conjunction with MValv. If MValv remains constant, and VCO2 decreases this represents a decrease in pulmonary blood flow, as less CO2 is eliminated even though minute ventilation at the alveolar level did not change. This is measured noninvasively and continuously to provide a real time dynamic measurement indicative of pulmonary blood flow and to alert clinicians of acute increases in pulmonary vascular resistance.
CASE STUDY: Infant delivered via Cesarean section at 38 4/7 weeks gestation secondary to non-reassuring fetal heart tracing. The infant had respiratory failure at birth secondary to meconium aspiration with progression to persistent pulmonary hypertension of the newborn. The patient was placed on conventional ventilator and INO. The NICO® Respiratory Profile Monitor was placed inline with the ventilator circuit. Data was collected on the patient for five days. With each INO wean the VCO2, blood gas results and ventilator settings were documented. By trending VCO2 we were able to detect changes in the CO2 production and dead space prior to obtaining a blood gas sample (see graph below). The patient's oxygen and ventilator settings remained unchanged throughout the data collection period.
DISCUSSION: INO improves oxygenation and V/Q matching in patients with hypoxemic lung disease. Using VCO2 in conjunction with INO therapy can aid the therapist in adjusting respiratory support within prescribed limits. In this patient we were able to effectively wean INO by trending VCO2 with the NICO® monitor. Drawing blood gases only when monitored values fall out of the prescribed range could improve respiratory treatment, reduce the incidence of barotrauma, reduce the exposure time to hypocapnia and hypercapnia and reduce the number and total volume of blood samples required.
CONCLUSION: By studying the VCO2 graph, we were able to observe ventilation by the shape of the graph and observe immediate feedback on V/Q changes. In this case, we were able to wean and discontinue INO therapy using VCO2.