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.