Utilization of surface electromyography during the feeding of term and preterm infants: a literature review

Aim  To evaluate studies that have used surface electromyography (sEMG) during feeding for term and preterm infants.
Method  Studies published between 1996 and 2009 were identified through databases (MEDLINE, EMBASE, CINAHL, LILACS, and SciELO) and divided into groups: term infants, preterm infants, and other situations with infants aged from 0 to 12 months.
Results  Five studies were found for suckling in term infants, two evaluating muscular activity during feeding in preterm infants, and one dealing with other situations. Some studies revealed striking differences in activity of the masseter muscle between breastfed and bottle-fed term infants (action diminished in bottle-fed infants). For preterm infants, authors evaluated sucking and sucking bursts and pointed out an effective means of evaluating muscle behaviour during feeding. There is evidence of a similarity in activity between cup feeding and breastfeeding.
Interpretation  Studies found in this literature review show the importance of using sEMG as a method of feeding assessment for term and preterm infants. For term infants, the masseter muscle presented greater muscular activity during breastfeeding and reduced activity during bottle-feeding. It was not possible to make comparisons between studies of preterm infants because of differences in methodological design.     

"Tuned" Defibrillation Waveforms Outperform 50/50% Tilt Defibrillation Waveforms: A Randomized Multi-Center Study

Introduction: A superior performance of a tuned waveform based on duration using an assumed cardiac membrane time constant of 3.5 ms and of a 50/50% tilt waveform over a standard 65/65% tilt waveform has been documented before. However, there has been no direct comparison of the tuned versus the 50/50% tilt waveforms.
Methods: In 34 patients, defibrillation thresholds (DFTs) for tuned versus 50/50% tilt waveforms in a random order were measured by using the optimized binary search method. High voltage lead impedance was measured and used to select the pulse widths for tuned and 50/50% tilt defibrillation waveforms.
Results: Delivered energy (7.3 ± 4.6 J vs 8.7 ± 5.3 J, P = 0.01), stored energy (8.2 ± 5.1 J vs 9.7 ± 5.6 J, P = 0.01), and delivered voltage (405.9 ± 121.7 V vs 445.0 ± 122.6 V, P = 0.008) were significantly lower for the tuned than for the 50/50% tilt waveform. In four patients with DFT ≥15 J, the tuned waveform lowered the mean energy DFT by 2.8 J and mean voltage DFT by 45 V. For all patients, the mean peak delivered energy DFT was reduced from 29 J to 22 J (24% decrease). Multiple regression analysis showed that a left ventricular ejection fraction <20% is a significant predictor of this advantage.
Conclusion: Energy and voltage DFTs are lowered with an implantable cardioverter defibrillator that uses a tuned waveform compared to a standard 50% tilt biphasic waveform.