J Med Cases

Journal of Medical Cases, ISSN 1923-4155 print, 1923-4163 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Med Cases and Elmer Press Inc

Journal website https://jmc.elmerpub.com

Case Report

Volume 16, Number 12, December 2025, pages 517-521

Remimazolam as an Adjunct to General Anesthesia During Surgery for Congenital Heart Disease in a Pediatric Patient With a Family History of Malignant Hyperthermia

**Table 1.** Summary of Perioperative Care and Events
Phase of care	Interventions
MH: malignant hyperthermia; IV: intravenous; CPB: cardiopulmonary bypass; CTICU: cardiothoracic intensive care unit; PVC: premature ventricular contraction; POD: postoperative day.
Preoperative preparation	MH-safe anesthetic planned. Anesthesia machine was prepared according to departmental policy, which included removal of the anesthesia vaporizers, a first case of the day start, changing of the carbon dioxide absorber and anesthesia circuit, and a high flow (10 L/min) flush of the anesthesia machine for 1 h.
	Dantrolene and other supplies available on MH cart
Premedication and placement of IV cannula	Oral midazolam (0.5 mg/kg)
	70% nitrous oxide in oxygen for placement of IV cannula
Induction of anesthesia	Remimazolam (10 µg/kg/min) and dexmedetomidine (0.5 µg/kg/min)
	Endotracheal intubation was facilitated by the administration of fentanyl (25 µg) and rocuronium (5 mg).
Pre-CPB maintenance	Remimazolam increased to 12 µg/kg/min and then to 15 µg/kg/min.
	Remifentanil started and continued at 0.3 µg/kg/min.
	Dexmedetomidine continued at 0.5 µg/kg/min.
CPB	Remimazolam and remifentanil continued at same doses.
	Dexmedetomidine discontinued during rewarming.
	Milrinone started at 0.25 µg/kg/min.
Post-CPB	Milrinone continued at 0.25 µg/kg/min.
	Remimazolam 15 µg/kg/min and remifentanil 0.3 µg/kg/min.
	Hypertension following CPB treated with bolus doses of propofol (2 - 4 mg/kg)
	Additional boluses of fentanyl (total 35 µg) and short-term use of a nitroprusside infusion (1 µg/kg/min).
	Residual neuromuscular blockade reversed with sugammadex.
Transport to CTICU	Remifentanil and remimazolam discontinued.
	Milrinone 0.25 µg/kg/min.
	Tracheal intubation and mechanical ventilation continued.
Postoperative course	Tracheal extubation at 4 h postoperatively and oxygen requirement weaned to room air over 24 h.
	No clinical signs concerning for MH.
	No rhythm disturbances other than occasional PVC (no treatment required).
	Milrinone infusion was discontinued on POD 1.
	Discharged to the inpatient ward on POD 2
	Discharged home on POD 6.

Table 1. Summary of Perioperative Care and Events

Phase of care

Interventions

MH: malignant hyperthermia; IV: intravenous; CPB: cardiopulmonary bypass; CTICU: cardiothoracic intensive care unit; PVC: premature ventricular contraction; POD: postoperative day.

Preoperative preparation

MH-safe anesthetic planned. Anesthesia machine was prepared according to departmental policy, which included removal of the anesthesia vaporizers, a first case of the day start, changing of the carbon dioxide absorber and anesthesia circuit, and a high flow (10 L/min) flush of the anesthesia machine for 1 h.

Dantrolene and other supplies available on MH cart

Premedication and placement of IV cannula

Oral midazolam (0.5 mg/kg)

70% nitrous oxide in oxygen for placement of IV cannula

Induction of anesthesia

Remimazolam (10 µg/kg/min) and dexmedetomidine (0.5 µg/kg/min)

Endotracheal intubation was facilitated by the administration of fentanyl (25 µg) and rocuronium (5 mg).

Pre-CPB maintenance

Remimazolam increased to 12 µg/kg/min and then to 15 µg/kg/min.

Remifentanil started and continued at 0.3 µg/kg/min.

Dexmedetomidine continued at 0.5 µg/kg/min.

CPB

Remimazolam and remifentanil continued at same doses.

Dexmedetomidine discontinued during rewarming.

Milrinone started at 0.25 µg/kg/min.

Post-CPB

Milrinone continued at 0.25 µg/kg/min.

Remimazolam 15 µg/kg/min and remifentanil 0.3 µg/kg/min.

Hypertension following CPB treated with bolus doses of propofol (2 - 4 mg/kg)

Additional boluses of fentanyl (total 35 µg) and short-term use of a nitroprusside infusion (1 µg/kg/min).

Residual neuromuscular blockade reversed with sugammadex.

Transport to CTICU

Remifentanil and remimazolam discontinued.

Milrinone 0.25 µg/kg/min.

Tracheal intubation and mechanical ventilation continued.

Postoperative course

Tracheal extubation at 4 h postoperatively and oxygen requirement weaned to room air over 24 h.

No clinical signs concerning for MH.

No rhythm disturbances other than occasional PVC (no treatment required).

Milrinone infusion was discontinued on POD 1.

Discharged to the inpatient ward on POD 2

Discharged home on POD 6.