CASE REPORT
Dexmedetomidine for awake fiberoptic intubation in a parturient with spinal muscular atrophy type III for cesarean delivery

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Abstract

Spinal muscular atrophy in pregnancy is rare and poses multiple problems for the anesthesiologist. The effects of dexmedetomidine on a parturient with spinal muscular atrophy have not previously been reported. There are also no in vivo data on placental transfer of dexmedetomidine and its effects on a human neonate. We report the hemodynamic, respiratory and sedative effects of dexmedetomidine on a parturient and neonate when used for awake fiberoptic intubation before cesarean section. A 35-year-old, gravida 4 para 0 aborta 3, 41-kg parturient at 35 weeks of gestation with spinal muscular atrophy presented for cesarean section. Dexmedetomidine was administered intravenously, total dose 1.84 μg/kg over 38 minutes, followed by fiberoptic endotracheal intubation. Dexmedetomidine was then discontinued and general anesthesia was induced. The baby was delivered 68 minutes after the dexmedetomidine infusion was discontinued at which time blood samples were obtained for measurement of dexmedetomidine. During administration of dexmedetomidine, maternal heart rate, blood pressure and oxygen saturation remained stable. Apgar scores at 1 and 5 min were 6 and 8. The fetal concentration of dexmedetomidine (540 pg/mL) indicates significant placental transfer, but significant adverse neonatal effects were not observed. Dexmedetomidine alone provided adequate sedation for awake intubation without respiratory compromise in this patient.

Introduction

Spinal muscular atrophy (SMA) has an estimated incidence of 1: 10 000 in the general population,1 and is rare during pregnancy. A case report identified 23 pregnancies in 18 women from 1966 to 1999.2 SMA, an inherited motor neuron disease, causes progressive degeneration of spinal cord anterior horn cells. It is characterized by diffuse voluntary muscle weakness and subsequent muscle atrophy, respiratory muscle insufficiency and scoliosis.[2], [3] These patients present multiple problems for the anesthesiologist including airway difficulties, respiratory compromise and spinal abnormalities. Multiple case reports describe anesthesia and analgesia for parturients with spinal muscular atrophy.[3], [4], [5], [6], [7] Dexmedetomidine, a central acting selective α2 agonist with minimal respiratory effects, is increasingly being used to facilitate awake fiberoptic intubation. Although the effect of increasing plasma concentrations of dexmedetomidine in adult humans has been described,[8], [9] at the time this case occurred the use of dexmedetomidine in a parturient had not been reported. Little is known about in vivo placental transfer of dexmedetomidine or about neonatal effects.

This case report describes the successful use of dexmedetomidine to facilitate awake fiberoptic intubation, with subsequent general anesthesia for cesarean delivery, in a parturient with spinal muscular atrophy type III.

Section snippets

Case report

A 35-year-old, 41-kg, 1.27-m, G4 P0 woman with SMA type III at 35+1 weeks presented for urgent cesarean section after premature spontaneous rupture of membranes. Past medical history was significant for anemia, asthma, thoracosacral spinal fusion and severe restrictive lung disease. Vital signs were blood pressure 123/89 mmHg, heart rate 94 beats/min, respiration 12 breaths/min, temperature 37.4°C and oxygen saturation 100% on room air. On examination she had a Mallampati class 4 airway with

Discussion

This patient presented multiple challenges to the anesthetic team. Extensive spinal fusion from high thoracic to sacral vertebrae precluded central neuraxial blockade. Her limited mouth opening, restricted cervical spine movement and inability to breathe with her head turned to the left all suggested that intubation by direct laryngoscopy was unlikely to be possible.

Awake fiberoptic intubation is our preferred method for securing the airway in patients with anticipated difficult airway.[10],

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