A Novel Approach to Identifying How Equipment Disrupts the Airflow Patterns in the Operating Room.

A decrease in the infection rates in the operating room (OR) is attributable to advances in sterile technique; heating, ventilation, and air-conditioning (HVAC) filtration; and limiting the number of people entering and leaving the OR. However, some infection complications after open heart procedures have been linked to the discharge fans of surgical equipment, most notably from the LivaNova 3T. We believe that surgical infection within the OR may also be due to other devices with internal fans. The purpose of this study was to 1) identify surgical equipment with an internal fan and see how they affect the airflow in an OR, 2) use the equipment to positively affect airflow to possibly reduce the risk of surgical site infections, and 3) bring attention to the HVAC system ability to exchange air throughout the OR. By using a fog machine and multiple camera angles, we identified the devices that have an effect on the airflow. We saw that the direction of the intake vent of specific devices can change the direction of airflow and possibly help to remove air. Last, we showed how the current HVAC air exchange rate might not be enough to remove contaminated air within the OR. Understanding intake and discharge vents for all equipment is important because sterile contamination and wound infection may be minimized or mitigated completely by simply repositioning a few devices.

Improved Estimation of Total Blood Volume Can Provide a Reliable Prediction of Dilutional Hematocrit and Oxygen Delivery during Cardiopulmonary Bypass.

Optimal oxygen delivery during cardiopulmonary bypass (CPB) for open heart surgery is crucial to protect organ function, improve outcomes, and reduce hospital stay. Effective preparation for optimal oxygen delivery during CPB is dependent on a reliable estimation of total blood volume (TBV) to accurately predict dilutional hematocrit (Hct) and calculate indexed oxygen delivery (iDO2). Unreliable estimation of TBV is a major reason for inaccurate prediction of dilutional Hct and iDO2. We performed a retrospective study of 113 patients who underwent cardiac surgery to compare the accuracy of predicted versus measured Hct and iDO2. We used four conventional methods of TBV estimation: 1) weight based A; 70 mL/kg for all patients, 2) weight based B; 70 mL/kg for males and 65 mL/kg for females, 3) Allen's formula, and 4) Nadler's formula. We found that TBV estimated by Allen's formula predicted dilutional Hct better than the other three. However, all four methods overestimate TBV when Hct is low and underestimate when Hct is high, suggesting that TBV is dependent on Hct in addition to body size and gender. Our analysis indicates that two individuals with the same body size and gender can have different TBV depending on Hct. We revised Allen's formula by adding a component that adjusts TBV depending on Hct to provide a more accurate prediction of dilutional Hct and iDO2.

An In-Vitro Study Comparing the GME Handling of Two Contemporary Oxygenators.

Gaseous microemboli (GME) are a potential complication of cardiopulmonary bypass (CPB). Though it is difficult to prove that GME is the only major cause of neurological deficits, it may increase the chance of post-operative cognitive dysfunction if not removed. The objectives of this research were to compare LivaNova-Sorin Inspire (Inspire) oxygenator with a Medtronic arterial filter to the Medtronic Fusion (Fusion) oxygenator with and without a Medtronic arterial filter based on each system's ability to handle GME. The Inspire and Fusion systems were evaluated in vitro. GME handling was observed by introducing air in the sampling manifold connected to the venous return at a 60 mL bolus or 1 liter per minute (LPM). The emboli detection and classification (EDAC) system measured GME preand post-oxygenator/arterial filter. The Inspire with a filter was able to remove a statistically significant greater amount of total emboli per second during the 60 mL bolus and 1 LPM tests than the Fusion with and without an arterial filter. The Inspire with an arterial filter was more efficient in removing GME during a 60 mL bolus and 1 LPM than the Fusion and Fusion with an arterial filter. However, the Fusion with an arterial filtered performed better than the Fusion system without the arterial filter.