The edition · Emergency & Critical Care
Two large analgesia trials cleared statistical significance and missed clinical importance
Intravenous magnesium added to paracetamol raised headache treatment success from 65.1% to 78.9% while every pain-score difference stayed below the 1.3-point threshold that matters, and 1,194 patients showed subcutaneous and intranasal ketamine equivalent for acute trauma pain.
The edition in brief
Two well-powered emergency analgesia trials landed this period, and both illustrate the same lesson about reading pain research. In 1,028 adults with acute non-traumatic headache, all of whom received oral paracetamol first, 2 g of intravenous magnesium sulphate against saline placebo raised treatment success — a 30% or greater fall in numerical rating scale at 30 minutes — from 65.1% to 78.9% (difference 13.8%, 95% CI 8 to 19). But every timed pain-score difference fell below the 1.3-point threshold accepted as clinically important. The secondary outcomes are the more persuasive part: rescue analgesia was needed by 7.1% against 15.3%, and satisfaction was higher, at the cost of more mild adverse events, 15.4% against 11.1%. A double-dummy trial randomised 1,194 patients with acute musculoskeletal trauma to 20 mg of ketamine subcutaneously or intranasally. Pain fell by 3.70 and 4.42 points respectively at 30 minutes, a difference of 0.72 (95% CI -0.95 to -0.48) — again statistically clear and again below 1.3. Minor adverse events were commoner with the subcutaneous route. Either route is a reasonable choice, which makes the decision one of practicality rather than efficacy. A trial of extracorporeal CO2 removal in ventilated COPD exacerbation was terminated by its sponsor for financial reasons after 18 of a planned 192 patients, leaving a shorter ventilation duration as a hypothesis rather than a finding. Annals of Emergency Medicine has published Delphi consensus guidelines on unscheduled procedural sedation.
Magnesium for headache: more patients responded, but not by much
Adding 2 g of intravenous magnesium to paracetamol for acute non-traumatic headache raised response rates and halved the need for rescue analgesia, though average pain-score gains stayed below the threshold for clinical importance.
Intranasal and subcutaneous ketamine worked equally well for trauma pain
Subcutaneous and intranasal ketamine at 20 mg produced no clinically important difference in pain relief for acute musculoskeletal trauma, so route can be chosen on practicality rather than efficacy.
A CO2-removal trial in ventilated COPD stopped at 18 of 192 patients
A trial of extracorporeal CO2 removal in ventilated COPD exacerbation stopped at 18 of 192 planned patients for funding reasons, so its shorter ventilation times are hypothesis-generating only and should not influence practice.
New consensus guidelines on unscheduled procedural sedation
No new emergency drug regulation today, but new two-part consensus guidelines on unscheduled procedural sedation address the emergency setting directly rather than borrowing elective theatre standards, and are worth reading against your local policy.
Learn the 1.3-point rule before you read another analgesia trial
In analgesia trials, look for whether the pain difference exceeds about 1.3 points on the numerical rating scale before believing a significant result matters, and weight event outcomes like rescue analgesia more heavily than mean scores.
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