Heart-Lung Bypass Oxygenators
Hazard [Health Devices Mar 1985;14(4):133]
A member hospital reported that the plastic shell of a disposable blood
oxygenator was severely damaged when liquid anesthetic spilled on it during a
cardiopulmonary bypass procedure. The perfusionist observed blood seeping out of cracks in
the oxygenator and interrupted extracorporeal perfusion to replace it. The patient
suffered no adverse effects from the interruption of circulation.
Since pulmonary blood flow is interrupted during bypass, inhalation
anesthesia must be administered via the oxygenator ventilation gases using a vaporizer to
combine the liquid anesthetic and oxygen. Because of the length of some bypass procedures,
some anesthesia vaporizers may not have sufficient capacity (or may not be adequately
filled during setup), and may require refilling during surgery.
In the reported incident, the vaporizer was found to be empty when
additional anesthesia was required late in the procedure. While pouring liquid Forane
(isoflurane) into the vaporizer filling port, the perfusionist accidentally spilled a
small amount (approximately 5 cc) onto the top of the bubble oxygenator, which was mounted
on the heart-lung console directly below the vaporizer. Apparently, the Forane acted as a
concentrated solvent and rapidly caused extensive cracking and crazing on the top of the
unit, particularly around its bonded seams. The sampling port reportedly melted off and
blood seeped out, forcing the perfusionist to halt extracorporeal perfusion for
approximately two minutes until a new oxygenator was located and installed. The
perfusionist minimized blood loss by salvaging the blood remaining in the oxygenator
reservoir. However, perfusionists do not wear sterile gloves during bypass and may
contaminate the setup while exchanging oxygenators.
We duplicated the reported interaction by applying halothane and
methoxyflorane to several manufacturers' oxygenators. Commonly used anesthetic agents are
powerful organic solvents that readily attack polycarbonate, the plastic material from
which disposable oxygenators, including the arterial filter and cardiotomy reservoir, are
generally made. Siliconized rubber or PVC tubing is normally used for both arterial and
venous lines, and do not appear to be affected.
Molding and bonding of plastic creates areas of stress concentration.
Liquid anesthetics can pervade these areas and severely degrade the polycarbonate. In
fact, applying a relatively light force to a damaged oxygenator's arterial outlet or
cardiotomy inlet can actually break it off.
Any breach of the oxygenator's exterior can introduce bacterial
contamination or cause critical blood loss. Also, replacing a damaged oxygenator during
bypass requires interrupting extracorporeal blood flow for several minutes and may
introduce air to the patient. Although metabolic activity and oxygen demand are
significantly lowered by induced hypothermia, cessation of extracorporeal blood flow
during bypass is extremely risky and may jeopardize the success of the surgical procedure,
particularly if perfusion is interrupted prior to cooling or during rewarming, when organ
oxygen demand is critical.
Many perfusionists and anesthesiologists are not aware of the danger of
exposing polycarbonate oxygenators to concentrated liquid anesthetics. In addition,
oxygenator and liquid anesthetic manufacturers currently do not label their products with
warnings about these harmful effects. All personnel involved with heart-lung bypass
surgery should be aware of the consequences of exposing polycarbonate oxygenators to
concentrated anesthetic agents and should take steps to prevent such events.
- Alert all perfusionists and anesthesia personnel to
- Never place an anesthesia vaporizer above or near
an oxygenator or any other polycarbonate device (e.g., blood filters,
- Ensure that the vaporizer is adequately filled
during setup to avoid refilling during the bypass procedure.
- Consider placing the following label on all heart-lung machine
WARNING: Concentrated liquid
anesthetics are powerful solvents and may damage plastic oxygenators. Do
not mount vaporizer above or near the oxygenator. Be careful not to
spill liquid anesthetic when filling
- Anesthesia Unit Vaporizers [10-144]
- Filters, Blood [11-713]
- Filters, Heart-Lung Bypass Priming [17-580]
- Heart-Lung Bypass Units [11-969]
- Oxygenators, Extracorporeal, Bubble [11-974]
- Oxygenators, Extracorporeal, Membrane [17-643]
- Reservoirs, Cardiotomy [13-338]
Cause of Device-Related Incident
Device factors: Design/labeling error; Device failure; Device interaction
User error: Accidental spill
Mechanism of Injury or Death
Exposure to airborne infectious agents; Exsanguination