The Nociception Level During General Anesthesia

The Nociception Level During Anesthesia in Patients Undergoing Video-assisted Thoracoscopic Surgery

We are conducting a study to evaluate two investigational devices that may help us better monitor discomfort or pain in anesthetized patients during minimally invasive lung surgery. We want to collect information on how people respond to pain related to their surgery. Currently, we use blood pressure (BP) and heart rate (HR) to check the response to pain. In this study, we will also use two devices called the Medasense PMD-100 and PhysioDoloris monitors to look at measurements of pain. We will compare the measurements from the study devices to the measurements of heart rate and blood pressure. We hope to enroll about 40 subjects in this study at the University of Washington Medical Center.

The following measurements will be collected during surgery for this research study.

1. Nociception Level (NoL) index The PMD-100 monitor includes a small probe similar to the pulse oximeter that will be placed on the subjects finger, which will be connected to the laptop placed next to the anesthesia machine. We will measure and record NoL index values at the following painful events: placement of breathing tube, skin incision, initial surgical instruments insertion and muscle relaxation assessment with a twitch monitor (60mA, 100Hz, 30sec). The anesthesiologist will be blinded to NoL index values that will only be collected for research purposes. We will compare the NoL index to ANI index, BP and HR. The measurements will start 5 minutes prior to the administration of general anesthesia and will continue until 5 min. after initial surgical instruments insertion.
2. Analgesia Nociception Index (ANI) index The PhysioDoloris monitor attached to the IV pole will be connected with a cable to the anesthesia monitor. We will measure and record ANI index values at the following painful events: placement of breathing tube, skin incision, initial surgical instruments insertion and muscle relaxation assessment with a twitch monitor (60mA, 100Hz, 30sec). The anesthesiologist will be blinded to ANI index values that will only be collected for research purposes. The measurements will start 5 minutes prior to the administration of general anesthesia and will continue until 5 min. after initial surgical instruments insertion.
3. Blood Pressure and Heart Rate We will also collect blood pressure and heart rate measurements that are generated as part of the standard anesthesia monitoring from electronic anesthesia record at 30 second intervals.
4. Bispectral Index We will also collect Bispectral Index (BIS) measurements that are generated as part of the anesthesia monitoring from electronic anesthesia record at 30 second intervals. BIS is a monitor of the depth of anesthesia that uses a sensor placed on patient's forehead. BIS monitor calculates a dimensionless number estimating the patient's level of consciousness. The BIS values range from 0 (no brain activity) to 100 (fully awake) with the target range between 40 and 60 for general anesthesia.
5. Pain Medication Data: We will collect the amount of pain medications used during the surgery from electronic anesthesia record.

Inclusion Criteria:

1. Patients who clinically consent to elective VATS procedure under general anesthesia,
2. Ages between 18 and 80 years,
3. Able to provide informed consent,
4. English speaking

Exclusion criteria:

1. violation of protocol (e.g., administration of medication that does not comply with the study protocol or inability to measure NoL or ANI index)
2. subject has change of mind
3. surgery has to be repeated.

Non-inclusion criteria:

1. subject refusal
2. non-English speaking
3. previous chronic or neuropathic pain
4. previous chronic use of opioids
5. history of psychiatric disorder
6. previous ipsilateral thoracotomy or VATS
7. morbidly obese with body mass index > 40
8. chronically treated with beta-blockers
9. unable to provide informed consent (we will not enroll subjects that require LAR consent)