Short summary

During this randomized trial on robotic colon surgical patients ( 30 in each group), study group receive analgesics guided by objective pain monitor i.e. NOL. The control patients receive standard treatment. Intraoperative and postoperative opioid consumption, quality of recovery and effect on myocardial function are assessed.

Rationale

During anesthesia for surgical procedures, anesthetic and muscle relaxant drugs can be meticulously administered using Bispectral Index (BIS) and neuromuscular monitors. However, analgesic drugs are still dispensed using poor surrogate parameters such as heart rate and blood pressure.This subjective dosing of analgesic drugs may invariably lead to intra-operative inappropriate consumption. This may result in tachycardia, hypertension, and postoperative pain due to e.g. insufficient analgesia, or hypotension, bradycardia, respiratory depression and Post-Operative Nausea and Vomiting (PONV).secondary to excessive analgesia. These effects may be detrimental to the patients especially those with multiple comorbidities and limited vital organ reserves such as patients classified by American Society of Anaesthesia classification (ASA) as 3 & 4. Similarly, immediate postoperative recovery may also get delayed due to pain, unstable hemodynamics, nausea and vomiting. In that context, there has long been search for a monitor which can guide meticulous administration of analgesics. Recently, a Nociception Level monitor (NOL) based on advanced software algorithms using multiple physiological parameters has been developed. It offers an objective score (NOL Index) which relates to the level of intra-operative pain. NOL technology has been validated and found superior to existing pain indicators in peer-reviewed publications.

A recent study showed that NOL-guided opioid administration was associated with a 30% reduction in intraoperative opioids usage (remifentanil) and 80% fewer hypotensive events. Considering the evidence that intraoperative hypotension increases the risk of myocardial injury, acute kidney injury and mortality, this study demonstrates the potential of NOL to reduce the probability of postoperative complications. A second study showed that intraoperative NOL values correlated with pain at mobilization on day 1 following surgery, and pain at movement 3 months following surgery, indicating that NOL may predict early and longer-term postoperative pain. A nociception level cut-off value of 20 yields specificity and sensitivity values of 80% and 73%, respectively, for discrimination between nonpainful and painful stimuli.

Being relatively new, the NOL monitor may offer interesting observations in perioperative nociception levels and appropriate analgesic consumption in diverse surgeries including robot assisted surgery. These observations may supplement the current efforts towards further advantages in rapid restitution. Therefore, we planned a trial where intra-operative analgesics were guided using NOL monitor.

Description of the cohort

Inclusion criterion:

American Society of Anaesthesiologists (ASA) class III-IV patients (aged 18 to 80 yrs.) of either sex, scheduled for elective major robot assisted colorectal surgeries, will be recruited to participate in the study.

Exclusion criteria:

Inability to give informed consent, planned spinal or epidural anaesthesia, all forms of regional anaesthesia including wound infiltration, nonelective procedures, pregnancy or lactation, atrial fibrillation.

Data and biological material

Patient`s journals will be screened for eligibility. Peioperative data which includes hemodynamic parameters, NOL and BIS parameters, drug doses , event timings etc will be accessed and saved for analysis. Preoperative and 24 hours post operative cardiac markers i.e. TnT and ProBNP will be measured.

Collaborating researchers and departments

Department of surgery ,South jutland hospital,Aabenraa.

Publications associated with the project

Stöckle P et al., (2018), Validation of the PMD100 and its NOL index to detect nociception at different infusion regimen of remifentanil in patients under general anesthesia. Minerva Anestesiologica; 84(10):1160-8.