Table 1.

Description of main and secondary variables

Main variables

Preoperative VAS score (0–10/10). 0 means absence of pain and 10 the severest pain imaginable

Postoperative VASscore (0–10/10) at 1st, 2nd, 4th, 6th postoperative days and at hospital discharge

(*)Range of sufentanil requirements (micro-pills per postoperative day)

1: 0–2 micro-pills (equal or less than 30 mcg/day)

2: 2–4 micro-pills (30–60 mcg/day)

3: 5–10 micro-pills (75–150 mcg/day)

4: More than 10 micro-pills (more than 150 mg/day)

(*) Range of morphine requirements per day (continuous perfusion plus PCA)

1: 0–30 mg/day

2: 30–60 mg/day

3: 60–150 mg/day

4: More than 150 mg/day

Requirement of methadone for breakthrough severe pain crisis

0: no use

1: < 10 mg/day

2: 10–15 mg/day

3: More than 15 mg/day

Secondary variables

Length of hospital stay (days)

Preoperative opioid requirement

0: No opioids or occasionally

1: Weak opioids (tramadol, codeine, tapentadol)

2: Strong opioids (fentanyl, oxycodone, morphine, buprenorphine)

3: Strong opioid combination

Opioid requirement at discharge

0: No opioids

1: Decrease compared to preoperative (between 20 and 30%)

2: Same dose compared to preoperative

3: More dose compared to preoperative

Postoperative nausea and vomiting

1: Yes

2: No

Paralytic ileus

1: Yes

2: No

Constipation

1: Yes

2: No

Requirement of Anxiolytics

0: No requirements

1: Once/day

2: Twice/day

3: 3 Times/day

4: More than 3 times/day

VAS visual analogue scale score

^(*)Opioid equivalences:

^(*)In order to compare daily and total opioid requirements (morphine vs. sufentanil), the following equivalence was assumed according to equipotent doses:

15 mg morphine (intravenous) = 15 mcg sufentanil (Sublingual) = 150 mcg sublingual fentanil

Based on the following equivalences:

10 mg i.v morphine = 100 mcg sublingual fentanyl = 30 mg oral morphine

Fentanil: sufentanil 10:1