Low-dose ketamine spared opioids in ventilated adults

Design

Prospective, double-blind, randomised, placebo-controlled trial

Population

120 mechanically ventilated ICU adults on opioid analgosedation (59 ketamine, 61 placebo)

Primary outcome

Hourly opioid dose (fentanyl equivalents)

Effect

64 vs 77 micrograms/hr; median difference -13 (95% CrI -26.6 to 2.4); 95% probability of benefit

A double-blind randomised trial at two Australian ICUs assigned 120 mechanically ventilated adults already receiving an opioid infusion to add a low-dose ketamine infusion (0.15 mg/kg/hr) or placebo, with the hourly opioid dose as the primary outcome.

Hourly opioid use (fentanyl equivalents) was lower with ketamine, 64 versus 77 micrograms per hour, a median difference of -13 (95% credible interval -26.6 to 2.4; 95% probability of benefit). There was no difference in delirium or most secondary outcomes, and no excess of significant adverse events.

The finding supports low-dose ketamine as a reasonable opioid-sparing adjunct in ventilated patients who need escalating opioid analgosedation, with a reassuring safety profile. The effect is modest, the trial small, and patient-centred outcomes such as ventilator-free days were not improved, so it is an option to consider rather than a new standard.

• Adding low-dose ketamine lowered hourly opioid use from 77 to 64 micrograms per hour (fentanyl equivalents).
• The probability of an opioid-sparing benefit was 95%, though the interval crossed zero.
• Delirium and most secondary outcomes did not differ between groups.
• No excess of significant adverse events was seen.
• Consider it an opioid-sparing adjunct, not a replacement for standard analgosedation.

Why it matters

It offers a way to limit opioid exposure during ventilation without evident added harm.

Don't overread it

Small, two-centre trial; it shows opioid sparing, not improvement in ventilator-free days or other patient-centred outcomes.

The statistics, in plain English

The 95% credible interval crosses zero, so the opioid-sparing effect, while probable (95% probability of benefit), is not definitive; a small single result like this is hypothesis-supporting, not practice-defining.

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