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The dose of propofol required to prevent children from moving during magnetic resonance imaging
D D Frankville1, R M Spear, J B Dyck
1Department of Anesthesiology, University of California, San Diego 92103-8770.
Insights
A propofol infusion rate of 100 micrograms.kg-1.min-1 effectively prevents movement in children during magnetic resonance imaging (MRI) scans. This dosage ensures successful anesthesia for pediatric MRI, with rapid recovery and minimal side effects.
Area of Science:
- Anesthesiology
- Pediatric Imaging
- Pharmacology
Background:
- Intravenous propofol is advantageous for pediatric anesthesia during magnetic resonance imaging (MRI).
- The propofol dose for MRI movement prevention may be lower than for surgical anesthesia.
Purpose of the Study:
- To determine the optimal propofol infusion rate for preventing movement in children during MRI.
- To evaluate the safety and efficacy of different propofol infusion rates in pediatric MRI.
Main Methods:
- Thirty pediatric outpatients (1-10 years) undergoing elective MRI were randomized to propofol infusion rates of 50, 75, or 100 micrograms.kg-1.min-1.
- Anesthesia was induced with halothane, nitrous oxide, oxygen, and a propofol loading dose.
- Movement during the scan was the primary observation endpoint.
Main Results:
- No significant differences in age, weight, induction, scan, or recovery times were observed across groups.
- Movement occurred in 50% of patients at 50 mcg.kg-1.min-1, 30% at 75 mcg.kg-1.min-1, and 0% at 100 mcg.kg-1.min-1.
- Transient decreases in oxygen saturation were noted post-bolus but resolved quickly; no hypoxemia or adverse events like nausea/vomiting occurred.
Conclusions:
- An infusion rate of 100 micrograms.kg-1.min-1 propofol, following induction, effectively prevents pediatric movement during elective MRI.
- A transient decrease in arterial oxygen saturation is a potential side effect of the initial propofol bolus.
- Rapid recovery without nausea or vomiting is characteristic of this anesthetic approach.
Background:
Intravenous propofol offers several advantages as an anesthetic for children undergoing magnetic resonance imaging. However, the dose of propofol required to prevent movement during magnetic resonance imaging is likely to be less than that required for surgical anesthesia.
Methods:
Thirty children between the ages of 1 and 10 years, undergoing elective magnetic resonance imaging as outpatients were randomly assigned to receive a propofol infusion at a rate of 50, 75, or 100 micrograms.kg-1.min-1 during the imaging procedure. Anesthesia was induced with inhalation of halothane, nitrous oxide, and oxygen, and a 2 mg.kg-1 loading dose of propofol. Immediately after insertion of an intravenous catheter, inhaled anesthetics were discontinued and the propofol infusion started. The children then were observed for movement during the scan.
Results:
There were no significant differences among the three groups with respects to mean age (4.4 +/- 2.0 yr), weight (17.6 +/- 5.1 kg), induction time (11 +/- 3 min), scan duration (55 +/- 26 min), or recovery time (30 +/- 8 min). Five of ten patients who received 50 micrograms.kg-1 x min-1 moved during the scan, three of ten patients who received 75 micrograms.kg-1 x min-1 moved, and none of the children who received 100 micrograms.kg-1 x min-1 moved. Two patients experienced a decrease of arterial oxygen saturation to less than 95% after receiving the initial bolus of propofol. The arterial oxygen saturation returned to normal within 15 s without specific treatment other than continued supplemental oxygen. There were no episodes of hypoxemia during image acquisition. None of the children experienced nausea or vomiting.
Conclusions:
Following induction of anesthesia with halothane, nitrous oxide, and a 2 mg.kg-1 loading dose of propofol, infusion of propofol at a rate of 100 micrograms.kg-1 x min-1 effectively prevents children from moving during elective magnetic resonance imaging. A transient decrease in arterial oxygen saturation can occur after the initial bolus of propofol. Recovery from anesthesia is rapid and without nausea or vomiting.