Anaes · Opioids & analgesics
Opioids & analgesics
Also known as Opioids · Fentanyl · Remifentanil · Morphine · Opioid-free anaesthesia · Patient-controlled analgesia · Opioid-induced respiratory depression · Opioid-sparing
The opioids and the analgesics in the perioperative care. The framework rests on the receptor pharmacology (the mu, the kappa, the delta), the agents (the fentanyl, the remifentanil, the morphine, the alfentanil, the sufentanil, the oxycodone, the tramadol, the methadone), the pharmacokinetics (the onset, the duration, the context-sensitive half-time), the adverse effects (the respiratory depression, the PONV, the constipation, the ileus, the tolerance, the dependence), the opioid-sparing multimodal strategy, and the opioid-free anaesthesia.
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- The opioid-induced respiratory depression is the life-threatening risk — the blunting of the central and the peripheral chemoreflex (the response to the CO2 and the O2). The Lewis review on the acute fentanyl toxicity — the opioid-induced and the hypoxia-mediated pathophysiology. The naloxone the reversal. The opioid-sparing and the opioid-free anaesthesia the modern strategy — the minimise the respiratory depression, the PONV, and the ileus. The PCA the patient-controlled but the monitored.
Meet the patient
A 68-year-old man is two hours out of an open bowel resection, on a morphine patient-controlled analgesia pump, four litres of oxygen by mask. The pulse oximeter reads 98 per cent, but his respiratory rate is six and he will not wake to a shake. The number that looked reassuring — the saturation — was masking the number that was killing him: the rate.[3]
This vignette holds the three ideas that run the whole topic: opioid analgesia is mu-mediated (so its harm is mu-mediated too), the kinetics decide which agent fits which moment, and respiratory depression is the killer that multimodal sparing, monitoring and naloxone exist to prevent. The lesson is the one the SpO2 teaches — an oxygen mask hides hypoventilation, so count the rate and look at the patient.[3][6]
References8ShowHide
- [1]Ayazbekova A, et al. Role of Opioid-Free Anesthesia Versus Opioid-Based Anesthesia in Postoperative Pain and Opioid Consumption: A Systematic Review and Meta-Analysis J Clin Med, 2026.PMID 42355728
- [2]Hughes DA, et al. Remifentanil patient-controlled analgesia for labour analgesia: guidance from the obstetric anaesthetists' association: Recommendations for well tolerated provision of remifentanil PCA for labour analgesia Eur J Anaesthesiol, 2026.PMID 42080744
- [3]Lewis T, et al. Acute Fentanyl Toxicity:From Opioid-Induced to Hypoxia-Mediated Pathophysiology J Neurophysiol, 2026.PMID 42333655
- [4]Peng YJ, et al. Opioid-induced respiratory depression: an underappreciated role of the peripheral nervous system J Neurophysiol, 2026.PMID 42166777
- [5]Hughes MA, et al. Context-sensitive half-time in multicompartment pharmacokinetic models for intravenous anesthetic drugs Anesthesiology, 1992.PMID 1539843
- [6]Beers R, et al. Remifentanil update: clinical science and utility CNS Drugs, 2004.PMID 15581380
- [7]Danel JK, et al. Opioid-sparing and opioid-free anaesthesia: concepts, rationale, evidence, and practical implications Anaesthesiol Intensive Ther, 2026.PMID 42638595
- [8]Lee M, et al. A comprehensive review of opioid-induced hyperalgesia Pain Physician, 2011.PMID 21412369