Air Embolism and CO2 Insufflators: The Need for Pre-Use Purging of Tubing
Hazard [Health Devices May-Jun 1996;25(5-6):214-5]
ECRI investigated a case of suspected gas embolism associated with carbon
dioxide (CO2) insufflation. During a hysteroscopy (performed with the patient
under intravenous sedation), the patient gasped for air almost immediately upon uterine
insufflation. Also, heart sounds suggesting intracardiac gas were heard. The procedure was
halted, and the patient recovered without further complication.
Based on the clinical signs, the medical staff suspected that the
patient's condition was caused by a CO2 embolism that originated in the uterus.
However, our investigation revealed that the embolized gas was probably air—not CO2.
The air may have been introduced into the patient from the dead space in the tubing set
used to connect the insufflator to the hysteroscope. This tubing set was not purged before
Symptomatic gas embolism can occur when undissolved gas (e.g., air, CO2)
accumulates in the heart and/or pulmonary arteries. This gas can compromise the
circulation of blood through the lungs, causing serious injury or death.
Gas embolism is of particular concern when using insufflators because
these devices introduce gas into the body at pressures that can exceed vascular pressure.
For example, during hysteroscopic insufflation, insufflators designed to deliver gas at
pressures up to 150 mm Hg (a pressure of 100 mm Hg is usually sufficient to distend the
uterus for hysteroscopic observation) and flow rates up to 100 mL/min are typically used.
If open vessels (primarily veins) are pre-existing or caused by cervical dilation or
distention of the uterus, the pressure can force gas into the uterine vessels, where the
blood flow can eventually carry any undissolved gas to the heart.
To minimize the risks of undissolved gas traveling to the heart when
insufflating various body cavities, a highly soluble gas—CO2—is used
in most cases. Using an animal model, Corson et al. (1988) examined the safety of using
this gas as a uterine insufflant. CO2 was infused at flow rates up to 90 mL/min
directly into the femoral vein of several female sheep for prolonged periods. Although
some hemodynamic changes occurred at the higher flows used, the sheep tolerated the direct
continuous infusion of CO2. This study showed that, because of the high
solubility of this gas in blood (54 mL/dL), CO2
bubbles entering from uterine
vessels were sufficiently dissolved during transit from the pelvic region before reaching
the heart. (For additional discussion of gynecologic gas embolism, see References.)
In the incident we investigated, symptomatic gas embolism resulting from
CO2 insufflation of the uterus seemed unlikely based on the findings described
in Corson et al. (1988). Thus, we examined whether air could have caused the patient's gas
embolism symptoms. Air is much less soluble than CO2, and it is considered
inappropriate as an insufflation gas for most procedures.
The reporting hospital informed us that insufflator flow was initiated
only after the hysteroscope was connected to the insufflator and the scope was inserted in
the patient's uterus. Thus, air present in the dead space in the tubing set used to
connect the insufflator to the hysteroscope could have been introduced into the patient.
Our tests revealed that the tubing used had a dead-space volume of 45 mL. Because only
about 50 mL of gas had been delivered at the time the procedure was stopped, we determined
that the uterus was most likely insufflated with air contained in the unpurged tubing set.
Another possibility, although less likely, is that the air embolism was
passively introduced. ECRI has received two reports of passive air embolism during
insertion of hysteroscopic instrumentation. In these cases, the placement of the patients
in the Trendelenburg position was a contributing factor. When the patient is tilted so
that her pelvis is raised higher than her heart, the blood pressure in the pelvic veins
may fall below atmospheric pressure and permit air to move into those veins. Thus, air
embolism can occur during hysteroscopy even when the uterus has not been pressurized by an
Regardless of the cause in the reported incident, the potential for
inadvertent insufflation with dead-space air, possibly resulting in air embolism,
certainly exists with hysteroscopic, as well as other, insufflators. For example, the use
of Verres needles for peritoneal access and subsequent gas instillation in preparation for
laparoscopy could permit infusion of gas directly into blood vessels if the needle tip is
accidentally placed within a vessel.
- Alert clinicians who set up and use CO2 insufflators to the risk of inadvertent air
insufflation caused by the failure to purge dead-space air from the
insufflation system before insufflating the patient.
- Placard insufflators as follows:
embolism hazard. (
If the insufflator does not have
sufficient space for the placard, consider placing this warning on the
- Immediately before delivering gas to the patient, purge air from
tubing sets and instruments with CO2. Allow 50 mL (cc) volume for each 6 ft (2 m) of 3/8 inch (10
- When possible, avoid placing the patient in the Trendelenburg position
for hysteroscopic examination.
Corson SL, Brooks PG, Soderstrom RM. Gynecologic endoscopic gas embolism. Fertility
and Sterility 1996 Mar;65(3):529-33.
Corson SL, Hoffman JJ, Jackowski J, et al. Cardiopulmonary effects of
direct venous CO2 insufflation in ewes: A model for hysteroscopy. J Reprod
Med 1988 May;33(5):440-4.
- Insufflators, Hysteroscopic [16-848]
- Insufflators, Laparoscopic [16-849]
Cause of Device-Related Incident
Device factor: Design/labeling error
User error: Incorrect clinical use
Support system failure: Failure to train
Mechanism of Injury Death