In rats, the chemical reduced the
strength of heart contraction by
50 percent; © SXC

These new findings suggest a possible new reason for some of the common side effects - loss of taste, short term memory loss, swelling and fatigue - of medical procedures that require blood to be circulated through plastic tubing outside the body, such as heart bypass surgery or kidney dialysis.

Principal investigator Artin Shoukas suspected that the trigger for these side effects might be a chemical compound. To test the theory, Shoukas and his team took liquid samples from IV bags and bypass machines before they were used on patients. The team analysed the fluids in another machine that can identify unknown chemicals and found the liquid to contain a chemical compound called cyclohexanone. The researchers thought that the cyclohexanone in the fluid samples might have leached from the plastic. Although the amount of cyclohexanone leaching from these devices varied greatly, all fluid samples contained at least some detectable level of the chemical.

The researchers then injected rats with either a salt solution or a salt solution containing cyclohexanone and measured heart function. Rats that got only salt solution pumped approximately 200 micro litres of blood per heartbeat and had an average heart rate of 358 beats per minute, while rats injected with cyclohexanone pumped only about 150 micro litres of blood per heartbeat with an average heart rate of 287 beats per minute.

In addition to pumping less blood more slowly, rats injected with cyclohexanone had weaker heart contractions. The team calculated that cyclohexanone caused a 50 percent reduction in the strength of each heart contraction. They also found that the reflex that helps control and maintain blood pressure is much less sensitive after cyclohexanone exposure. Finally, the team observed increased fluid retention and swelling in the rats after cyclohexanone injections.

Despite these findings, "We would never recommend that patients decline this type of treatment if they need it," says Shoukas. "On the contrary, such technologies are life-saving medical advances, and their benefits still far outweigh the risks of the associated side effects. We are simply trying to understand how the side effects are triggered and what the best method will be to mitigate, and ultimately remedy, these morbidities."

COMPAMED.de; Source: Johns Hopkins Medical Institutions