Results
The CONSORT flow diagram of this trial is shown in Figure 1. Patients
were recruited between December 10, 2021 and May 25, 2022. Of the 67
patients who underwent thyroid surgery and were screened for
suitability, 7 were excluded, of whom 2 had uncontrolled hypertension
and 5 declined to participate. Ultimately, 60 patients were enrolled and
randomized, all of whom were followed up until the end of the study.
Table 1 shows patient and surgical characteristics. There were no
significant differences between groups in age, sex distribution, BMI,
ASA physical status, type of surgery, or duration of surgery (Table 1).
Compared with the Group CON, perioperative sufentanil consumption was
significantly reduced in Group KET (33. 7 ± 5.1 μg vs. 24.6 ± 3.1 μg,
mean difference, 9.1; 95% confidence interval, 6.9–11.3, P<0.001). There were no significant differences between the two
groups in regards of intraoperative remifentanil consumption (1118.5 ±
294.9 μg vs. 1045.8 ± 302.0 mg, P = 0.349) or propofol
consumption (513.50 ± 210.0 mg vs. 476.2 ± 170.1 μg, P = 0.453)
(Table 2).
Postoperatively, five patients in Group CON and no patients in Group KET
reported NRS scores >3; however, this did not reach
significance. None of the patients received rescue analgesia in the
PACU. In the ward, one patient in Group CON required analgesic therapy,
and diclofenac lidocaine was administered by the attending surgeon.
There were no significant differences between groups with regard to the
time to extubation or RASS score 30 min postoperatively. The incidence
of postoperative nausea was 3.3% in Group CON and 13.3% in Group KET,
whereas the incidence of postoperative vomiting was 6.7% in Group CON
and 10.0% in Group KET; however, these differences were not
statistically significant. Psychotomimetic side effects were not
significantly different between groups. The most common side effect was
dizziness (CON: 30.0% vs. KET: 27%, P = 0.774). One patient in
Group KET experienced transient diplopia, which resolved spontaneously
over time. None of the patients experienced hallucinations or
nightmares, and none reported intra-operative awareness after surgery
(Table 3).
Patients in Group KET experienced lower NRS pain scores at rest and
coughing than those in Group CON at all timepoints in the first 24 h
postoperatively (Figure 2). . Pain scores in 3 months postoperatively
were equally low and comparable between the two groups (Table 3).
Preoperative sleep quality scores were comparable between the two
groups. During the night of surgery, patients in Group KET experienced
higher sleep quality (2 [1, 2]) than those in Group CON (3 [1,
4]) (P = 0.043). When we compared the intragroup values using
the Wilcoxon matched-pairs test, patients in Group CON reported
significantly poorer sleep quality when compared with the preoperative
value (preoperative value, 1 [1, 2] vs. postoperative value, 3
[1,4], P = 0.004); however, there was no significant
difference between the preoperative and postoperative values in Group
KET in terms of sleep quality (preoperative quality, 2 [1,4] vs.
postoperative quality, 2 [1,2], P = 0.347, Table 3).
There were no significant differences in MAP between groups at any
timepoints. Patients in Group KET exhibited a higher HR 10 min after
injection of esketamine, while HR values were similar at other
timepoints between groups (Figure 3). The incidences of hypotension and
bradycardia in Group CON (13.3% and 10.0%, respectively) were both
comparable with those in Group KET (13.3% and 0%, respectively), and
none of the patients exhibited hypertension or tachycardia.