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Midazolam following open heart surgery in children: haemodynamic effects of a loading dose
A J Macnab1, M Levine, N Glick
1Department of Paediatrics, British Columbia's Children's Hospital, Vancouver, Canada.
Insights
This study investigated midazolam loading doses for pediatric postoperative sedation after heart surgery. Results showed no clear systematic hemodynamic effects, but a single adverse event led to study discontinuation.
Area of Science:
- Pediatric Critical Care Medicine
- Cardiothoracic Surgery Anesthesia
- Pharmacology
Background:
- Postoperative sedation is crucial for children after open heart surgery.
- Midazolam is commonly used, but its safety with loading doses requires evaluation.
- Hemodynamic stability is a primary concern in this vulnerable population.
Abstract:
Our objective was to establish the safety and effectiveness of a loading dose of midazolam for postoperative sedation of children recovering from open heart surgery; a prospective randomized placebo-controlled double-blind study was done with subjects randomized to three groups according to loading dose. I = 0.08 mg.kg-1; II = 0.04 mg.kg-1; and III = 0.00 mg.kg-1 (placebo). An open label continuous midazolam infusion protocol followed. Haemodynamic parameters were monitored. The study was discontinued following an adverse event involving the 23rd subject. When data for all 23 subjects were combined, there was a mean decrease of 10% in blood pressure (BP) 30 min after the loading dose (P < 0.001). Heart rate change was less significant. Clinicians identified four hypotensive episodes as temporally associated with the midazolam load, two each in Groups I (0.08 mg.kg-1) and III (placebo). One subject in Group I (the 23rd) became hypotensive within five min of receiving the loading dose, had a difficult clinical course and died four weeks postoperatively. We cannot conclude that the loading dose of midazolam had any systematic haemodynamic effect in our study population. Although the clinical course of the 23rd subject suggests a subset of more susceptible children (those who receive opioid analgesia with midazolam, are volume-restricted, and/or undergo more complex forms of surgical correction), many critical care patients are inherently physiologically unstable, and concluding clinically that blood pressure fluctuation is drug related may be erroneous.