A study in Anesthesiology details a noninvasive nociception monitor that gauges a patient's pain during surgery.
Researchers used intraoperative nociception levels and compared them to heart rate, pulse plethysmograph amplitude, noninvasive blood pressure and the surgical pleth index around five specific stimuli:
- Tetanic stimulation with fentanyl analgesia
- Tetanic stimulation without fentanyl analgesia
- Intubation
- First incision/trocar insertion
- A nonnoxious period.
Here's what they found.
1. In 58 patients, the NoL index responded to increased stimulus intensity and remained unchanged in response to non noxious stimuli.
2. The researchers compared the NoL index to other accepted measures of nociception, and the index better recognized noxious from non noxious stimuli with an area under the curve of 0.93 and a sensitivity of 87 percent at 84 percent specificity.
3. The NoL index also "reliability reflected two different analgesic concentrations of remifentanil during initial skin incision or trocar insertion."
Researchers made three conclusions:
- The index changed proportionately with patients' response to clinical and experimental noxious stimuli, while also recognizing the different stimuli with high degrees of sensitivity and specificity.
- The index responded to increased intensity while it was appropriately "blunted" by analgesic administration.
- The index was superior to other measures and "accurately characterizes nociception during general anesthesia."