Intraoperative Fentanyl Consumption Guided by Analgesia Nociception Index

A Comparative Study of Intraoperative Fentanyl Consumption Guided by Analgesia Nociception Index Versus Standard Protocol in Patients Undergoing Mastectomy

Balanced anesthesia needs optimization of hypnotic, relaxant, and narcotic. Administration of hypnotic drugs can be monitored by bispectral index score (BIS), while the dosage of muscle relaxants can be guided by train-of four (TOF). However, administration of narcotics lacks objective monitor. Overdosage of narcotic may lead to delayed awakening, while underdosage may lead to high degree of postoperative pain. Recently, there is a monitor, Analgesic Nociceptive Index (ANI) monitor, designed to guide the administration of narcotics. There are many descriptive studies supporting the correlation of ANI score and pain score but there are still very few randomized control studies which report the efficacy of ANI in clinical practice.

Objective: To evaluate the efficacy of ANI to guide the administration of intraoperative fentanyl. Methods: Sixty female patients undergoing breast surgery with balanced anesthesia will be randomized into 2 groups. The first group will receive fentanyl according to standard practice of attending anesthesiologists. The second group will receive fentanyl according to ANI score protocol. Primary outcome: Postoperative pain numeric rating scale (NRS) score during 60 minutes in postanesthetic care unit (PACU). Secondary outcomes: Total intraoperative dose of fentanyl and postoperative nausea/vomiting and sedation score in PACU.

ANI score 50-70 indicates optimal narcotic effect. ANI score > 70 indicated overdosage of narcotic and narcotic should be withheld. ANI score < 50 indicates inadequate narcotic and narcotic should be given.

Measure pain numeric rating scale (NRS) every 15 minutes. NRS has a range from 0 to 10 with 0 indicates no pain while 10 indicates worst pain. NRS of 0-3 is mild, 4-6 is moderate, and 7-10 is severe pain.

Intraoperative ANI score of both groups. ANI has a range from 0 to 100 with 0 indicates worst pain while 100 indicates no pain. ANI 0-49 suggests that more opioid is needed. ANI 50-70 indicate optimal analgesic and no opioid is needed. ANI > 70 indicates excessive effect of opioid and opioid should be withheld.

Nausea/vomiting score (PONV score) every 4 hours. PONV score has a range of 0 to 3. N/V scores 0= none, 1= mild, 2= moderate, and 3= severe PONV.

Sedation score every 4 hours. Sedation score has a range of 0 to 3 with 0= fully alert, 1= mild sedation, easy to rouse, 2= moderate sedation, arousable with gentle shaking, and 3= deep sedation, not aroused by speaking or gentle shaking.

Inclusion Criteria: Adults female undergoing elective breast surgery American Society of Anesthesiologists (ASA) classification I-III Body mass index (BMI) 18.5-35 kg/m2 Exclusion Criteria: Implanted pacemaker Cardiac arrythmia Autonomic nervous system (ANS) disorder, e.g. epilepsy, stroke Chronic opioid use Chronic pain On beta-blocker, calcium channel blocker, or other drugs to control arrythmia Previous mastectomy Pregnancy On Nsaids

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