To the Editor:—
Drs. Ho and Ling's excellent Meeting Abstracts article, “Systemic Air Embolism after Lung Trauma,”1provides an important teaching service to the anesthesia community. However, one totally preventable and recurring cause of potentially fatal venous air embolism that was not mentioned in the article (particularly in the last section entitled, “Other Causes of Air Embolism in Nontraumatic and Traumatic Clinical Setting”) is externally pressurizing a reinfusion blood bag that has been filled with blood from a surgical field scavenging–blood processing system. In most of the Haemonetics blood scavenging–processing models (Cell-Saver; Haemonetics Corp., Braintree, MA), the unit sends an 80-ml column of air ahead of the first column of blood into the reinfusion blood bag. If the reinfusion blood bag, which contains air, is then externally pressurized, a venous air embolism may occur. The obvious, but life-saving, take-home message of these considerations is that reinfusion blood bags that have been filled with blood from an autotransfusion system should never be externally pressurized.
The old warning on the Haemonetics Cell-Saver reinfusion bag of “Do Not Use With Pressure Cuff” was changed to “Do Not Use Pressure Cuff. The Use of Pressure Cuff May Lead to Fatal Infusion of Air” in 1995 for obvious reasons. However, I am aware that the practice of externally pressurizing Cell-Saver reinfusion blood bags is still common and widespread. Consequently, other additional solutions to minimize the risk of fatal venous air embolism appear to be desirable and necessary. The potential solutions include insertion of a air bubble detector with an audible alarm in the infusion line to the patient, routine use of a double reinfusion bag (transfer pack) system, redesign of the processing unit to exclude air from being sent to the reinfusion bag (mandatory use of a purge mechanism), and insertion of a nondependent air escape valve in the reinfusion bag. All these solutions involve an additional response to the problem by the manufacturer. Certainly any two in-series solutions (e.g. , the printed warning on the reinfusion bag plus one of the above suggestions) for the air in the reinfusion bag problem will greatly minimize the risk of venous air embolism.