Remifentanil has been reported to cause post-anesthetic shivering (PAS). Higher doses of remifentanil reportedly induce more intense PAS. Tramadol, a synthetic opioid that acts at multiple sites, is considered to be an effective treatment for PAS, but the evidence for its therapeutic benefit after remifentanil anesthesia is limited. We investigated the effect of tramadol on the incidence of PAS after remifentanil anesthesia. Sixty-three patients who had undergone upper abdominal surgery under general anesthesia were studied retrospectively. Tramadol was administered at induction of anesthesia. The patients were divided into four groups: HT(+), high dose remifentanil (1–1.5 μg/kg/min) with tramadol; HT(−), high dose remifentanil without tramadol; LT(+), low dose remifentanil (0.15–0.25 μg/kg/min) with tramadol; and LT(−), low dose remifentanil without tramadol. We recorded perioperative changes in nasopharyngeal temperature and episodes of PAS on emergence from anesthesia. The incidences of PAS in both tramadol treatment groups were significantly lower than the groups that did not receive tramadol. Nasopharyngeal temperature after surgery fell significantly more from baseline in the tramadol treatment groups compared with the non-treatment groups. Tramadol administered at induction of anesthesia appears to suppress PAS following remifentanil anesthesia.

Purpose: Remimazolam, a newly developed ultra-short-acting benzodiazepine, provides early recovery of consciousness but its effects on memory recovery are unclear. This study examined memory recovery after emergence from general anesthesia using remimazolam. Methods: Seventy-four patients undergoing breast surgery between October 2021 and March 2022 were enrolled and randomly assigned to receive propofol (control group) or remimazolam as general anesthetic during surgery. The primary endpoint was the number of posters patients remembered 24 h after surgery (among four posters shown after recovering from anesthesia) as an assessment of memory retention. The secondary endpoints were the recall of a numeric character patients had been shown just before anesthetic induction, as an assessment of retrograde amnesia 24 h after surgery. Results: Sixty-six patients (propofol, 32; remimazolam, 34) were assessed. Patients in the remimazolam group remembered significantly fewer posters shown to them after surgery than those in the propofol group (0 [0 − 2] vs. 2 [1 − 3], p < 0.001). In the remimazolam group, the patients who received flumazenil remembered a higher number of posters than those who did not receive flumazenil (3 [1 − 4] vs. 0 [0 − 0], p < 0.001). All patients remembered all events that occurred during the preoperative period as well as the numeric character. Conclusion: Patients recovering from remimazolam anesthesia without receiving flumazenil do not remember events after regaining consciousness. IRB: Kyushu University School of Medicine Hospital Institutional Review Board (IRB) (approval number: 20212006). Trial registration: This clinical trial was registered with the University Hospital Medical Information Network (UMIN) Center on September 28, 2021 (UMIN-CTR: UMIN000045593). Implication statement: Memory recovery is slower following emergence from remimazolam than from propofol anesthesia.

Background: Bleeding and carbon dioxide (CO₂) gas embolism have been reported as serious complications associated with laparoscopic surgery. We present a case of cerebral infarction presumably caused by CO₂ gas embolism during laparoscopic hepatectomy. Case presentation: During liver resection, the end-tidal CO₂ suddenly dropped from 40 to 21 mmHg. Simultaneously, ST elevation in lead II and ST depression in lead V5 of the electrocardiogram were observed. After improvement of these electrocardiographic changes, surgery was continued. Postoperatively, incomplete paralysis was present in the right arm and leg. Magnetic resonance imaging revealed cerebral infarction in the broad area of the left cerebral cortex. These complications might have been caused by paradoxical embolism. Conclusion: We should always keep in mind the risk of cerebral infarction with neurological deficits in the case of laparoscopic surgery. Careful monitoring and appropriate treatment for gas embolism are necessary during laparoscopic surgery.