For the first time, surgeons may be able to objectively gauge the level of painful stimulation being inflicted on an anesthetized patient, according to a study published in the Online First edition of Anesthesiology. Being able to monitor — and hopefully limit — the patient's pain may actually improve procedure outcomes and reduce post-operative side effects.

The measure, called nociception (pain) level index, uses algorithms to process a patient’s hormonal and neurological reactions so physicians can know earlier on the patient’s reflex response during the procedure. Physicians can also determine how traditional methods like monitoring heart rate and blood pressure compare to the index.

“There’s currently no standardized, objective method for physicians to monitor the effectiveness of pain relieving drugs being administered during surgery,” said Dr. Ruth Edry, lead study author and senior physician anesthesiologist at Rambam Medical Center, in a statement.
In the study, 58 patients who had general anesthesia for different surgical procedures were examined using both routine anesthesia monitoring and a pain monitoring device which would generate the pain index.

The index was assessed at various times during the procedure including intubation and skin incision, which are considered “noxious” stimuli that would be painful to a conscious person. The patients’ index results were then compared to the traditional methods.

The researchers discovered that during surgery, the pain index discriminated pain-causing stimuli from non-pain-causing stimuli better than traditional means. Also, it was able to quantify the body’s response to increased painful stimulation with high sensitivity and specificity.

Patients are unconscious during general anesthesia, but their body still has reflex responses to the surgical procedure, including changes in heart rate, blood pressure, eyes tearing or sweating, according to the announcement, and these unwanted reflexes can sometimes be dangerous.

“Not effectively monitoring bodily responses to painful stimulation could lead to insufficient amounts of pain medication being administered, which can result in the patient having severe pain upon regaining consciousness from anesthesia, while too much medication may cause other side effects such as nausea and vomiting or respiratory complications,” Edry said.

“Our results demonstrate the superiority of combining multiple physiologic measures over any individual parameter in the evaluation of the body’s response to pain during surgery,” said Edry, and added that once in clinical practice, the team can conduct large-scale studies to assess the influence of this monitor on patient outcomes.

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