Opioid-free cardiac anaesthesia scrapes a win, and it is a fragile one

The edition in brief

OFACAR randomised 320 adults having elective cardiac surgery with cardiopulmonary bypass to opioid-free anaesthesia (ketamine, dexamethasone, lidocaine, magnesium) or sufentanil. The composite of neurological, respiratory, cardiovascular or renal complications or death at 30 days fell from 84.5% to 75.4% (RR 0.90, 95% CI 0.80 to 0.99, P = 0.049). The fragility index was 1: one patient changing groups would have erased significance, and the authors call the result hypothesis-generating. Digestive complications were markedly lower (2.5% vs 11.2%) and there were no deaths in the opioid-free arm against six. A meta-analysis of 114 trials and 13,951 surgical patients found HES 130/0.4 or 130/0.42 did not raise acute kidney injury (RR 1.02, 95% CI 0.91 to 1.16) or worsen creatinine (-0.62 micromol/l, 95% CI -3.82 to 2.57). Trial sequential analysis reached adequate information size. Most exposure was under 24 hours in theatre, which is not the septic ICU population the FDA boxed warning came from. A population pharmacokinetic study in 44 volunteers, 30 with obstructive sleep apnoea, found total body weight drove remimazolam clearance while apnoea severity did not. Context-sensitive half-time after a four-hour infusion was 4.02 minutes in class 2/3 obesity. Lean or ideal body weight for induction and adjusted body weight for maintenance reproduced normal-weight exposure. A network meta-analysis of 158 randomised trials and 18,794 patients found regional anaesthesia reduced chronic postsurgical pain at up to 12 months (RR 0.73, 95% CI 0.67 to 0.80), with benefit in mastectomy, thoracotomy, video-assisted thoracoscopic surgery and knee arthroplasty. Neuraxial beat peripheral techniques for thoracic surgery. Long-term opioid use did not differ. Certainty was low.