Effect of Remifentanil on the Recovery Profile After Prolonged Head and Neck Surgery
Effect of Remifentanil on the Recovery Profile After Prolonged Head and Neck Surgery
Opioid tolerance in the perioperative period is inevitable especially with ultra-short acting
 agents such as remifentanil. Existing evidence had shown that opioid induced hyperalgesia due
 to neuroplastic changes in the central as well as peripheral nervous system leads to
 sensitization of pro-nociceptive pathways. However there has been a controversy of occurrence
 of such tolerance following the use of remifentanil and the quality of recovery as compared
 to conventional opioids. The investigators evaluated the occurrence of opioid tolerance and
 other significant adverse effects with remifentanil in subjects undergoing head and neck
 surgeries. The investigators studied ASA physical status I and II adult subjects undergoing
 elective head and neck procedures, under general anesthesia with minimum expected duration of
 2 hours. The remifentanil infusion was used in one group and intermittent boluses of morphine
 or fentanyl administered in another group. They were evaluated for immediate post-operative
 pain by using numerical rating scale (NRS), the opioid consumption, post-operative nausea,
 vomiting, other significant adverse effects of remifentanil and the time to discharge from
 PACU.
We have studied 222 of you between the age of 21 and 80 years, over a period of 2 years at
 Singapore General Hospital, Singapore. All of you were ASA I to II and scheduled for elective
 head and neck surgery with minimum expected duration of 2 hours, requiring general
 anesthesia. The methodology of this observational study was approved by the International
 review Board at Singapore General Hospital, Singapore. Informed consent was obtained from you
 prior to the procedure. If you had previous history of either drug or alcohol abuse, have
 been using opioids for long term, mental disorder with difficult to understand pain scoring
 system, ASA physical status of III and above, your surgical procedure warranting elective
 postoperative ventilation you would have been excluded from this study. The study was not
 randomized and the choice of intra-operative opioids were left to the discretion of
 anesthesiologist attending you.

 You were not premedicated and instructed about 11 point numerical rating score after reaching
 induction room. Upon arrival in the operating room, you were monitored with EKG, non-invasive
 arterial pressure and pulse oxymetry. The attending anesthesiologist gave you either
 Remifentanil or conventional opioids at standard doses from the induction of anesthesia to
 end of surgery. Sevoflurane, desflurane or isoflurane with oxygen air mixture were utilized
 to maintain anesthesia at the minimum alveolar concentration of 0.8 to 1.2 . Choice of
 opioid, volatile agent, muscle relaxants, airway was left to the discretion of the
 anesthesiologist attending the patient. Parameters including type of volatile anesthetic
 agent, method of air way establishment, the duration of surgery, the remifentanil used
 (microgram.kg-1 ) and amount of morphine or fentanyl (microgram.kg-1) were documented. Upon
 arrival to the PACU you were assessed for the pain.

 For the first 15 minutes behavioral score (0 - calm patient with no verbal or behavioral
 manifestation of pain, 1 - behavioral or verbal expression of pain, and 2 - intense
 behavioral or verbal manifestation [crying or extreme agitation]) were utilized and
 subsequently numerical rating scale (NRS) was used for every 5 minutes until discharge from
 the PACU.

 Intravenous morphine or fentanyl was used to treat immediate post-operative pain in PACU till
 the NRS is less than or equal to 3 as per PACU acute pain management protocol. Maximum NRS of
 pain, amount of morphine or fentanyl used for rescue analgesia, occurrence of either nausea
 or vomiting and the antiemetic used was gathered every 15 minutes. Upon discharge from the
 PACU, total opioids consumed, duration of the PACU (defined by time since admission to
 decision made for discharge by PACU anesthesiologists, to rule out the prolong PACU stay from
 other reasons) and occurrence of other potential side effects that affect the quality of
 recovery such as drowsy, nausea, vomiting, shivering and evidence of respiratory suppression
 ( desaturation or bradypnea ) were documented.

 Our primary outcome was amount of opioids used in PACU and the secondary outcomes were the
 duration of PACU stay and the adverse effects of remifentanil that influence the recovery as
 stated above.
Inclusion Criteria:

 Patients with ASA I to II, scheduled for elective head and neck surgery with minimum
 expected duration of 2 hours, requiring general anesthesia

 Exclusion Criteria:

 previous history of either drug or alcohol abuse those who have been using opioids for long
 term mental disorder with difficult to understand pain scoring system ASA physical status
 of III and above surgical procedure warranting elective postoperative ventilation