Validation of Venous Cannulae Flow Ratings

During bypass, venous drainage is essential for maintaining proper perfusion of a pediatric
patient. The quality of venous drainage has a large impact on the level of care the patient
is provided. This study will investigate blood flow velocities through right angle venous
cannulae which are utilized during bypass. The flows from each cannulae will be analyzed by
using doppler flow probes which employ Transit Time Technology. This type of technology has
crystals within the flow probes which send magnetic signals through the tubing with the
purpose to determine the most accurate flows of blood. There is little evidence that
identifies the actual amount of blood flow generated from each venous cannulae in a clinical
setting. Manufacturers of venous cannulae for CPB publish flow ratings for the different
sized cannulae available. These flow ratings are gathered from data produced in a
non-clinical lab and are often very inaccurate. Because of this inaccuracy, selection is
based on experience rather than published clinical data. This study would be instrumental in
determining any and all potential risks or benefits to the patient as a result of the amount
of drainage provided by the venous cannulae during bypass. A sample size of 50 patients
(n=50) over one day old will be utilized for this study. The specific venous cannulae sizes
that will be analyzed are the 12Fr, 14Fr, 16Fr, 18Fr, 20Fr, 24Fr, & 28Fr DLP (DLP and Fr are
the type and size of cannulae, respectively) right angle cannulae. The doppler flow probes
that will be utilized during this study are reusable, non-invasive, clamp-on devices which
measure blood flow through the CPB tubing. Each patient will have one flow probe placed on
each venous cannulae prior to starting CPB. Bypass itself will not be altered in anyway.
Hemoglobin blood levels, blood temperature, and pressure from the venous line will be
recorded throughout CPB and are digitally sampled via the CPB machine (e.g. no blood draw
required). To further examine the quality of venous drainage, a pressure transducer will be
attached to the venous line measuring the amount of negative pressure being generated by the
venous cannulae. The negative pressure line will be attached to the venous line at a
stopcock that is already present in our CPB circuit. Each cannulae size will be analyzed
three times to acquire the proper amount of data needed to fulfill the statistical and
practical needs for the study. A descriptive analysis of the continuous and categorical data
will be performed using means, standard deviations, confidence intervals, proportions, and
frequency distributions. Statistical testing will include parametric and non-parametric
bi-variate and multi-variate techniques as appropriate to the variables' level of
measurement and distributions.

Inclusion Criteria:

- All Patients that require cardiopulmonary bypass during cardiac surgery.

Exclusion Criteria:

- The only exclusion criteria would be if CPB is not required for surgical repair.