Hypothermia during RARP: No significant benefit seen

Although theory and preliminary clinical data indicated that intraoperative regional hypothermia could improve the return to potency and continence after robot-assisted radical prostatectomy (RARP), the intervention did not have any significant benefits when put to the more rigorous test of a randomized controlled trial.

Results of the latter investigation, however, did underscore the critical role of surgeon skill in the post-RARP course of recovery, reported researchers from the University of California, Irvine (UCI), at the European Association of Urology annual congress in London.

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“Most single-surgeon studies report that advancing age is an independent factor for delaying return of continence and reducing overall continence rates following RARP, and it is believed that inflammation is the key mediator for these outcomes, with the presumption being that older men do not recover from the inflammation induced by surgical trauma as well as younger patients. The idea for regional hypothermia is to provide a local anti-inflammatory effect, and we found it had benefit in a single-surgeon study,” said Linda Huynh, BS, assistant research specialist in urology at UCI.

“With further evaluation, however, in a multinational randomized controlled trial involving five high-volume surgeons recruited from outside of our institution, any potential benefit of hypothermia was overwhelmed by the consequences of significant individual surgeon outcome. These results are hypothesis-generating. They suggest that surgeon skill dwarfs the impact of anti-inflammatory action from regional hypothermia and that minimizing surgical trauma is much more effective than accepting the trauma and trying to preemptively prevent the inflammatory process with hypothermia,” Huynh added.

The technology used for regional hypothermia during RARP was developed and patented by researchers in the UCI department of urology in 2009. It consists of an endorectal cooling balloon that circulates 4°C saline in the rectum to reduce the local tissue temperature to about 20°C during RARP.

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Thomas Ahlering, MD, professor and vice chairman of urology at UCI, performed all of the procedures in the single-surgeon study. Young Hwii Ko, MD, a visiting research professor from Korea, was lead author of the study that included 930 non-high risk men who underwent nerve-sparing RARP. The population was comprised of two sequentially operated series, the first including 464 men who had a standard, normal thermic procedure and the next 466 who received regional hypothermia. All men had a minimum follow-up of 12 months post-RARP.

Postoperative potency was defined by data from the 5-item International Index of Erectile Function (IIEF-5) questionnaire and required a score >17. Return of continence was defined as being pad-free. Outcomes were analyzed with men divided into two groups defined based on age and preoperative IIEF-5 scores. Group 1 included men aged <66 years with an IIEF score of 22-25. Group 2 was comprised of men who were aged ≥66 years or who were younger but had an IIEF-5 score of 17-21.

Next: IIEF-5 score improvement observed

IIEF-5 score improvement observed

Linear regression analysis showed that in both groups, regional hypothermia significantly improved IIEF-5 scores at all postoperative time intervals, and it was also associated with significantly earlier time to pad-free continence.

“The positive results in the single-surgeon study prompted us to conduct a randomized controlled trial,” said Huynh. “In all randomized controlled trials investigating the value of surgical devices, however, individual surgeon skill exists as an unknown confounding variable.”

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In the adjusted analysis of data from the randomized controlled trial, regional hypothermia improved potency and continence outcomes only for the subgroup of patients operated on by one of the five surgeons.

Dr. AhleringDr. Ahlering told Urology Times, “For the single-surgeon study, Dr. Ko performed a superlative statistical analysis of our database. The results confirmed our previous finding and validated our concept about regional hypothermia, which helped us intellectually. In the randomized controlled trial, however, the benefit did not apply to most surgeons.

“We believe the explanation is that the anti-inflammatory benefit of regional hypothermia manifests if the surgery is technically well done. If the surgeon is too rough and causes too much iatrogenic trauma, regional hypothermia provides no measurable benefit, not even a trend.”

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