Cardiac contractility modulation: A new technologically advanced placebo?
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Defibrillators, Implantable↗
Biomedical subjects
Sunil K Sinha
Publications and source records attributed to Sunil K Sinha.
Observation of a low-viscosity interface between immiscible polymer layers.
X-ray photon correlation spectroscopy was employed in a surface standing wave geometry in order to resolve the thermally driven in-plane dynamics at both the surface/vacuum (top) and polymer/polymer (bottom) interfaces of a thin polystyrene (PS) film on top of Poly(4-bromo styrene) (PBrS) and supported on a Si substrate. The top vacuum interface shows two relaxation modes: one fast and one slow, while the buried polymer-polymer interface shows a single slow mode. The slow mode of the top interface is similar in magnitude and wave vector dependence to the single mode of the buried interface. The dynamics are consistent with a low-viscosity mixed layer between the PS and PBrS and coupling of the capillary wave fluctuations between this layer and the PS.
Journal Article↗
Surface and interfacial dynamics of polymeric bilayer films.
The theory for surface dynamics of the thermally excited fluctuations on a homogenous single-layer film of arbitrary depth is generalized to describe surface and interfacial dynamics of polymeric liquid bilayer films in terms of susceptibilities, power spectra, and characteristic relaxation time constants. The effects on surface dynamics originating from viscosity inhomogeneities close to the surface and interfacial regions are investigated by the bilayer theory and compared with the surface dynamics of homogeneous single-layer films under nonslip and slip boundary conditions. Our bilayer theory can also be extended to study interfacial dynamics of more generalized multilayer systems. The effects of viscoelasticity and van der Waals interactions on surface and interfacial dynamics are also briefly discussed.
Journal Article↗
Fetal-to-neonatal maladaptation.
Although the majority of newly born babies will establish normal respiratory and circulatory function without help, 1-2% might run into difficulties because of a disturbance in the normal adaptive processes required for a smooth transition from intrauterine to extrauterine life. An understanding of the normal and abnormal perinatal physiology is important to appreciate the practical differences in the approach to caring for such babies, and also for avoiding actions that might be detrimental in the longer term.
Adaptation, Biological↗
Mechanical ventilation of very low birth weight infants: is volume or pressure a better target variable?
OBJECTIVE: To compare the efficacy and safety of volume-controlled (VC) ventilation to time-cycled pressure-limited (TCPL) ventilation in very low birth weight infants with respiratory distress syndrome (RDS). STUDY DESIGN: Newborns weighing between 600 and 1500 g and with a gestational age of 24 to 31 weeks who had RDS were randomized to receive either VC or TCPL ventilation and treated with a standardized protocol. The 2 modalities were compared by determining the time required to achieve a predetermined success criterion, on the basis of either the alveolar-arterial oxygen gradient <100 mm Hg or the mean airway pressure <8 cm H(2)O. Secondary outcomes included mortality, duration of mechanical ventilation, and complications commonly associated with ventilation. RESULTS: The mean time to reach the success criterion was 23 hours in the VC group versus 33 hours in the TCPL group (P = .15). This difference was more striking in babies weighing <1000g (21 versus 58 hours; P = .03). Mean duration of ventilation with VC was 255 hours versus 327 hours with TCPL (P = .60). There were 5 deaths in the VC group and 10 deaths in the TCPL group (P = .10). The incidence of other complications was similar. CONCLUSION: VC ventilation is safe and efficacious in very low birth weight infants and may have advantages when compared with TCPL, especially in smaller infants.
Female↗
Surfactant trials.
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Biological Products↗
Resonantly enhanced off-specular X-ray scattering from polymer/polymer interfaces.
We have used measurements of the absolute intensity of diffuse X-ray scattering to extract the interfacial tension of a buried polymer/polymer interface. Diffuse scattering was excited by an X-ray standing wave whose phase was adjusted to have a high intensity at the polymer/polymer interface and simultaneously a node at the polymer/air interface. This method permits the capillary-wave-induced roughness of the interface, and hence the interfacial tension, to be measured independently of the polymer/polymer interdiffusion.
Algorithms↗
Real-time evolution of the distribution of nanoparticles in an ultrathin-polymer-film-based waveguide.
We report a novel application of an ultrathin-polymer-film-based, resonance-enhanced x-ray waveguide as a real-time nanoprobe for elucidating dilute, yet disordered, gold nanoparticles embedded in the polymer matrix. This nanoprobe promises a sensitivity enhancement of several orders of magnitude, hence revealing in real time the lateral nanoparticle distribution with subnanometer spatial resolution. We observed that the motion of the nanoparticles is strongly anisotropic, with in-plane coalescence taking place more rapidly than out-of-plane diffusion, which can ultimately facilitate the formation of two-dimensional structures.
Journal Article↗
Electrophysiologic interventions in patients with inferior vena cava filters: safety and efficacy of the transfemoral approach.
OBJECTIVES: The purpose of this study was to evaluate the transfemoral venous approach for electrophysiologic interventions in patients with inferior vena cava filters. BACKGROUND: Reports have detailed complications associated with obtaining central venous access in patients with inferior vena cava filters. Accordingly, electrophysiologic interventions have been modified or deferred altogether in such patients. METHODS: Patients requiring interventions with a transfemoral approach who were at least 3 months post filter insertion underwent fluoroscopically guided insertion and withdrawal of electrode catheters with appropriate follow-up. RESULTS: Five patients underwent successful pacing, electrophysiologic study, or radiofrequency ablation using one to three catheters, with no complications attributable to filter placement. CONCLUSIONS: Transfemoral electrophysiologic interventions can be safely undertaken across vena cava filters provided appropriate precautions are taken.
Aged↗
Radiofrequency ablation of Mahaim pathway during atrial fibrillation.
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Adult↗
A multicenter, randomized, controlled trial of lucinactant versus poractant alfa among very premature infants at high risk for respiratory distress syndrome.
BACKGROUND: Available therapeutic surfactants are either animal-derived or non-protein-containing synthetic products. Animal-derived surfactants contain variable amounts of surfactant apoproteins, whereas the older-generation synthetic products contain only phospholipids and lack surfactant proteins (SPs). Both decrease morbidity and mortality rates associated with respiratory distress syndrome (RDS) among preterm infants, compared with placebo. However, excess mortality rates have been observed with non-protein-containing synthetic surfactants, compared with the animal-derived products. Evidence suggests that synthetic surfactants consisting solely of phospholipids can be improved with the addition of peptides that are functional analogs of SPs. Lucinactant is a new synthetic peptide-containing surfactant that contains sinapultide, a novel, 21-amino acid peptide (leucine and lysine repeating units, KL4 peptide) designed to mimic human SP-B. It is completely devoid of animal-derived components. OBJECTIVE: We hypothesized that the outcomes for premature infants treated with lucinactant and poractant alfa would be similar. Therefore, we compared lucinactant (Surfaxin; Discovery Laboratories, Doylestown, PA) with porcine-derived, poractant alfa (Curosurf; Chiesi Farmaceutici, Parma, Italy) in a trial to test for noninferiority. METHODS: A total of 252 infants born between 24 and 28 weeks of completed gestation, with birth weights between 600 and 1250 g, were assigned randomly in a multicenter, multinational, noninferiority, randomized, controlled study to receive either lucinactant (n = 124) or poractant alfa (n = 128) within 30 minutes of life. The primary outcome was the incidence of being alive without bronchopulmonary dysplasia (BPD) through 28 days of age. Key secondary outcomes included death at day 28 and 36 weeks postmenstrual age (PMA), air leaks, neuroimaging abnormalities, and other complications related to either prematurity or RDS. An independent, international, data and safety monitoring committee monitored the trial. RESULTS: The treatment difference between lucinactant and poractant alfa for survival without BPD through 28 days was 4.75% (95% confidence interval [CI]: -7.3% to 16.8%) in favor of lucinactant, with the lower boundary of the 95% CI for the difference, ie, -7.3%, being greater than the prespecified noninferiority margin of -14.5%. At 28 days, 45 of 119 infants given lucinactant were alive without BPD (37.8%; 95% CI: 29.1-46.5%), compared with 41 of 124 given poractant alfa (33.1%; 95% CI: 24.8-41.3%); at 36 weeks PMA, the rates were 64.7% and 66.9%, respectively. The corresponding mortality rate through day 28 for the lucinactant group was lower than that for the poractant alfa group (11.8% [95% CI: 6.0-17.6%] vs 16.1% [95% CI: 9.7-22.6%]), as was the rate at 36 weeks PMA (16% and 18.5%, respectively). There were no differences in major dosing complications. In addition, no significant differences were observed in the incidences of common complications of prematurity, including intraventricular hemorrhage (grades 3 and 4) and cystic periventricular leukomalacia (lucinactant: 14.3%; poractant alfa: 16.9%). CONCLUSIONS: Lucinactant and poractant alfa were similar in terms of efficacy and safety when used for the prevention and treatment of RDS among preterm infants. The ability to enhance the performance of a synthetic surfactant with the addition of a peptide that mimics the action of SP-B, such as sinapultide, brings potential advantages to exogenous surfactant therapy.
Biological Products↗
Prevention of sudden cardiac death: the role of the implantable cardioverter-defibrillator.
Sudden cardiac death, usually due to fatal ventricular tachyarrhythmias, results in the loss of 300,000-400,000 lives each year in the United States. Implantable cardioverter-defibrillator therapy has revolutionized both the secondary and, increasingly, the primary prevention of sudden cardiac death. In the last decade, subcutaneous pectoral implantation with transvenous lead placement has lessened perioperative risk considerably, raising the benefit/risk ratio for many candidates. As a consequence, the list of approved indications for implantable cardioverter-defibrillator therapy has expanded rapidly in recent years. Current devices offer tiered therapy utilizing bradycardia pacing, anti-tachycardia pacing, low-energy cardioversion, and high-energy defibrillation. Hybrid therapy, combining device, drugs and radiofrequency catheter ablation as required, has become the standard of care for reducing both appropriate and inappropriate shocks. As implantation rates continue to rise, so will the number of patients presenting with electrical storm. The dilemma of how our society will cope with the enormous projected costs of implantable cardioverter-defibrillator therapy has yet to be resolved.
Death, Sudden, Cardiac↗
Prevention of sudden cardiac death and diabetes mellitus.
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Anti-Arrhythmia Agents↗
Can mechanical ventilation strategies reduce chronic lung disease?
Chronic lung disease (CLD) continues to be a significant complication in newborn infants undergoing mechanical ventilation for respiratory failure. Although the aetiology of CLD is multifactorial, specific factors related to mechanical ventilation, including barotrauma, volutrauma and atelectrauma, have been implicated as important aetiologic mechanisms. This article discusses the ways in which these factors might be manipulated by various mechanical ventilatory strategies to reduce ventilator-induced lung injury. These include continuous positive airway pressure, permissive hypercapnia, patient-triggered ventilation, volume-targeted ventilation, proportional assist ventilation, high-frequency ventilation and real-time monitoring.
Bronchopulmonary Dysplasia↗
The controversies surrounding oxygen therapy in neonatal intensive care units.
Despite the knowledge that excess amounts of oxygen in the blood (hyperoxia) can be damaging to preterm infants, there is a wide variation in approaches to oxygen therapy within neonatal intensive care units. This is predominantly determined by institutional or individual practices or preferences and might stem from a lack of understanding of the relative merits and demerits of the different techniques of oxygen monitoring in extremely preterm babies who are different from more mature babies. This article provides the physiological rationale and evidence from recent clinical studies suggesting that keeping the oxygen therapy to an "acceptable" minimum in premature babies does not do any harm and may be even advantageous.
Disease Progression↗
Invasive and noninvasive neonatal mechanical ventilation.
Neonatal respiratory failure consists of several different disease entities, with different pathophysiologies. During the past 30 years technological advances have drastically altered both the diagnostic and therapeutic approaches to newborns requiring mechanical assistance. Treatments have become both patient- and disease-specific. The clinician has numerous choices among the noninvasive and invasive ventilatory treatments that are currently in use. This article reviews the pathophysiology of respiratory failure in the newborn and the available methods to treat it, including continuous positive airway pressure, conventional and high-frequency mechanical ventilation, extracorporeal membrane oxygenation, and styles of ventilation and monitoring.
Extracorporeal Membrane Oxygenation↗
Newer techniques of mechanical ventilation: an overview.
The introduction of newer, state-of-the-art, microprocessor controlled ventilator systems provides clinicians with opportunities to apply a number of advanced ventilatory modalities which were not previously available for treating newborns. Some of these techniques will need further scientific evaluation in controlled trials, but this should not preclude their use in clinical settings, as their safety has already been proved by "standard setters" for use in neonates. There is a firm physiological rationale for their use, and individual centres have already acquired substantial experience in the application of these modalities. The trend towards increasing sophistication and greater versatility is likely to continue, and clinicians involved in the care of sick newborn infants must keep abreast of these developments.
Equipment Design↗
Weaning newborns from mechanical ventilation.
While there is a relative consensus as to whether mechanical ventilation should be initiated, the management of babies during recovery from respiratory failure remains largely subjective and is predominantly determined by institutional or individual practices or preferences. This can lead to babies either being left on the ventilator too long, or extubated too hastily, thus requiring repeated re-intubation. The current scientific literature fails to provide a uniform view of the most appropriate way to wean babies from mechanical ventilation. This might stem from a lack of understanding of the relative merits of the different techniques of discontinuing mechanical ventilation, given the availability of a variety of primary ventilatory modes which were not available to a neonatal population before, and limited research into the pathophysiological mechanisms responsible for an unsuccessful extubation. The purpose of this paper is to review the physiological, mechanical, and clinical principles of weaning, and to highlight areas still in need of investigation.
Clinical Competence↗