Understanding time to peak effect of propofol as sole agent on bispectral index in children aged 2-12 years.

BACKGROUND: The pharmacodynamics of propofol in children have previously been described with the proprietary bispectral index (BIS) as an effect-site marker, and it has been suggested that the rate of onset of propofol might be age dependent, that is, a shorter time to peak effect in younger children. However, these analyses were potentially confounded by co-administered drugs, in particular opioids and benzodiazepines. Thus, the goal of this prospective study was to characterize the influence of age and weight on the onset of hypnotic effects from propofol, reflected by the time to peak of propofol effect-site concentration in the absence of additional drugs. METHODS: A total of 46 healthy children aged 2-12 years presenting for elective surgery were included in our observational cohort study. Solely propofol was administered via a target-controlled infusion pump programmed with the Paedfusor pharmacokinetic model. The BIS and infusion pump data were recorded. The effect of an induction "bolus" was recorded having stopped the pump once a propofol plasma target concentration of 7 µg.mL-1 was achieved. A direct-response and an indirect-response model in the context of nonlinear mixed-effects modeling was used to characterize and compare BIS data in children aged 2-6 years and older children aged 8-12 years. RESULTS: Time to peak of propofol effect-site concentration had a difference (p-value <.01) for age and weight, that is 84 [74, 96] (median [IQR] secs for children aged 2-6 years vs. 99 [91, 113] secs for children aged 8-12 years and 82 [71, 95] secs for weight 11-25 kg vs. 99 [91, 114] secs for weight 30-63 kg). The plasma effect-site equilibration rate constant for propofol had a heterogeneous distribution with a median of 2.36 (IQR: 2.05-2.93; range: 0.83-7.31) per minute but showed a weight-dependent effect in patients with weight below 45 kg. CONCLUSIONS: In children, the age and weight have an influence on time to peak effect of propofol. In the absence of opioids and benzodiazepines, time to peak effect was approximately 20% longer in children aged 8-12 years as compared to younger children. Such clinically relevant age and weight effects are an important consideration in the individualized titration of propofol dosing.

Minimal invasive interlaminar approach for untethering of fatty filum terminale in pediatric patients - how I do it.

BACKGROUND: Fatty filum terminale is a form of spinal dysraphism and a third of all patients develop symptoms such as sensory, motor, and urinary impairment. Early surgery at 6 months has the advantage that the bone density is still soft, and the patients are not ambulatory yet, promoting faster healing. METHOD: We present our minimal invasive surgical technique for FFT untethering. CONCLUSION: Due to the low complication rate and the potentially high benefit of surgery, prophylactic untethering is recommended.

Spinal Surgery With Electrically Evoked Potential Monitoring and Monopolar Electrocautery: Is Prior Removal of a Cochlear Implant Necessary?

: Transcranial electric stimulation to generate motor evoked potentials in lower limb muscles is the standard technique used to monitor spinal cord efferent pathways during surgical correction for spinal deformities. Monopolar electrical cauterization is also used by default in the thoracic and lumbar area of the spine during this kind of surgery to prevent major blood loss. Owing to the high levels of current used, both techniques are considered contraindicative if the patient has a cochlear implant (CI). Here, we present a CI patient who underwent corrective spinal fusion surgery for a severe kyphoscoliotic spinal deformity on whom both techniques were used without any negative effects on the CI function. A major improvement in sagittal body balance was achieved with no loss in implant-aided hearing levels. These results add to reports that CI manufactures should review their evidence underlying recommendations that transcranial electric stimulation and upper thoracic monopolar electrical cauterization are high risk for CI users, possibly initiating verification studies.

Diffusion abnormalities in the primary sensorimotor pathways in writer's cramp.

OBJECTIVE: To determine whether there are diffusion abnormalities along the fibers connecting sensorimotor regions, including the primary sensorimotor areas and the striatum, in patients with writer's cramp using voxel-based diffusion analysis and fiber tracking. Recent studies have shown structural changes in these regions in writer's cramp. DESIGN: Patient and control group comparison. SETTING: Referral center for movement disorders. PARTICIPANTS: Twenty-six right-handed patients with writer's cramp and 26 right-handed healthy control subjects matched for sex and age. INTERVENTIONS: Clinical motor evaluations. MAIN OUTCOME MEASURES: Fractional anisotropy changes and results of fiber tracking in writer's cramp. RESULTS: Diffusion-tensor imaging revealed increased fractional anisotropy bilaterally in the white matter of the posterior limb of the internal capsule and adjacent structures in the patients with writer's cramp. Fiber tracking demonstrated that fractional anisotropy changes involve fiber tracts connecting the primary sensorimotor areas with subcortical structures. CONCLUSIONS: Diffusion abnormalities are present in fiber tracts connecting the primary sensorimotor areas with subcortical structures in writer's cramp. These abnormalities strengthen the role of the corticosubcortical pathways in the pathophysiologic mechanisms of writer's cramp.