Israeli researchers have devised a multivariable index that appears to accurately reflect patients’ experience of pain during surgery.
This kind of objective “pain measurement” is the holy grail of pain management, but I wouldn’t trust it – would you?
I suspect not.
Pain is such a primal sensation with a literally overpowering impact that I cannot bring myself to trust some device, no matter how ingenious, to detect the enormity and full significance of this sensation.
“The primary significance of our findings is that we have proved that it is possible to accurately and objectively assess patients’ nociceptive state—or ‘pain’—based on an algorithmic combination of multiple physiological parameters, creating the NoL [nociception level] index,” said Ruth Edry, MD.
“We were able to identify—in anesthetized, noncommunicating, surgical patients—a patient’s response to noxious stimuli and the effect of analgesic administration, as well as grade the patient’s response to noxious stimuli of varied levels and distinguish different doses of analgesia during a similar noxious stimulus.”
“Using a nociception monitor … and NoL index may enable the anesthesiologist, or any other interventionist managing patients during invasive procedures, to optimize the intraoperative administration of analgesics, keeping the patient more hemodynamically stable during the procedure,” Dr. Edry explained.
The NoL index operates within a clinical device that evaluates a nonlinear combination of the following variables in order to provide clinicians with an objective pain measurement:
- heart rate;
- heart rate variability;
- plethysmographic pulse wave amplitude;
- skin conductance;
- skin conductance fluctuations; and
- the time derivatives of these measures.
In this study, the authors examined the correlation between the results of the NoL index and other measures of nociception.
The NoL index was run on the PMD-100, a nociception monitor manufactured by Medasense Biometrics.
The study included 58 patients undergoing a variety of surgical procedures, including laparoscopic and open abdominal surgeries with intubation. The researchers found that “the NoL index responded progressively to increased stimulus intensity and remained unchanged in response to nonnoxious stimuli.”
Compared with other accepted measures of nociception, the NoL index better discriminated noxious from nonnoxious stimuli with an area under the curve of 0.93 (95% CI, 0.89-0.97).
The NoL index/PMD-100 had a sensitivity of 87% at a specificity of 84%.
“The NoL index was the only measure that reliably reflected two different analgesic concentrations of remifentanil [Ultiva, Mylan] during initial skin incision or trocar insertion,” the authors noted.
“Our study shows that NoL … is an intensity-sensitive measure that is blocked by opioid administration. Titrating to NoL may thus guide clinicians and help them give patient-specific optimal amounts of intraoperative opioid,” Dr. Sessler explained.
This multicenter trial included researchers in the Department of Outcomes Research at the Cleveland Clinic, which is chaired by Daniel I. Sessler, MD, and who is the Michael Cudahy Professor of Anesthesiology in the Department of Anesthesiology at the Cleveland Clinic.
Dr. Sessler said this new device is “important.”
A search for “Cleveland Clinic” on this blog found posts from which you can see that this famous clinic has fallen for the “alternative medicine” myth:
How can I trust an organization which no longer conforms to scientific realities? If they tell me they have a device that can measure my pain, why would or should I believe them?
Drs. Sessler and Edry reported personal financial interests in the new device.
“Our study shows that NoL … is an intensity-sensitive measure that is blocked by opioid administration.
Titrating to NoL may thus guide clinicians and help them give patient-specific optimal amounts of intraoperative opioid,” Dr. Sessler explained.
Paul White, MD, PhD, was not as impressed by the findings. “This appears to be a well-conducted clinical study with predictable results.
Previous studies have reported that each of these variables have some predictive value, so the combination would be expected to be stronger than any one alone,” he said.
Dr. White is not taken in by this promoted “new” device and he sees nothing special about it.
The accepted measures to which Dr. White was referring included
- heart rate,
- plethysmographic pulse wave amplitude,
- noninvasive blood pressure and
- the surgical pleth index around five specific stimuli:
- tetanic stimulation
- with and without fentanyl analgesia,
- first incision/trocar insertion and
- the nonnoxious period.
“The real question is whether the use of this device has any significant influence on measurable clinical outcomes (e.g., recovery times, side effects, adverse events [intraoperative recall], pharmacoeconomics, OR [operating room] efficiency, patient safety, etc.). Otherwise, it is just another expensive toy.”
—John Henry Dreyfuss