Outcomes From Long-Distance Interfacility Transport of Adult Patients on Acute Mechanical Circulatory Support.

Cardiac and respiratory failure in adults has historically had very high mortality. Mechanical circulatory support (MCS) has shown promise to improve outcomes for these patients; however, only tertiary care centers typically have the critical care resources to manage patients on MCS. We investigated to see if we could provide safe, long-distance transport of MCS-supported patients to our tertiary center after MCS is initiated at community or regional hospitals. We also investigated if we could provide this service without using physicians or perfusionists for the en route management of MCS devices. Our outcome results, based on survival to discharge, are comparable with other published survival outcomes data for this patient population, suggesting that patients on MCS devices can be safely transported by air and ground without incurring additional mortality risk. Additionally, instead of perfusionists or physicians, specially trained nurses were used to manage all MCS devices en route. This change to the typical transport team structure has the potential to make the transport of MCS-supported patients more cost-effective for health care systems nationwide.

Safety of long-distance transfers of patients on acute mechanical circulatory support.

BACKGROUND: Acute mechanical circulatory support (aMCS) can be a lifesaving therapy for patients with refractory cardiogenic shock. As device safety and technology improve, so will the ability to extend aMCS to patients at remote hospitals. The Intermountain West is unique because of the large geographical area, making transport of critically ill patients a logistical challenge. METHODS: We reviewed our experience of transporting patients in cardiogenic shock over long distances who had already been placed on aMCS: Impella and extracorporeal membrane oxygenator devices. Survival data was compared to international benchmark data published by the Extracorporeal Life Support Organization. RESULTS: A total of 11 patients (91% male; mean age 56 ± 5.4 y) were transported via fixed-wing aircraft to our center. The etiology of cardiogenic shock was ST-elevation myocardial infarction (n = 4), acutely decompensated chronic systolic heart failure (n = 4), postcardiotomy shock (n = 2), and acute myocarditis (n = 1). Average transport distance was 364 ± 139 miles (585 ± 264 km) and flight time was 170 ± 29 min. All patients were safely transported with no in-transit adverse events. The average duration of aMCS was 6.4 ± 3.3 d. Six patients (54.5%) survived to device explantation and 3 (27.2%) survived to hospital discharge. For comparison, Extracorporeal Life Support Organization benchmark data for adult cardiogenic shock patients report 56% survival to device explantation and 41% to hospital discharge. CONCLUSIONS: Patient transport with aMCS over long distances can be done safely without serious adverse events using good protocols and well-trained personnel. Although survival data are slightly below benchmark data, they appear reasonable, given the severity of illness and challenges of transferring critically ill patients to an expert center.

Techniques for Accurate Sizing of Gold Nanoparticles Using Dynamic Light Scattering with Particular Application to Chemical and Biological Sensing Based on Aggregate Formation.

Gold nanoparticles (AuNPs) have found broad applications in chemical and biological sensing, catalysis, biomolecular imaging, in vitro diagnostics, cancer therapy, and many other areas. Dynamic light scattering (DLS) is an analytical tool used routinely for nanoparticle size measurement and analysis. Due to its relatively low cost and ease of operation in comparison to other more sophisticated techniques, DLS is the primary choice of instrumentation for analyzing the size and size distribution of nanoparticle suspensions. However, many DLS users are unfamiliar with the principles behind the DLS measurement and are unware of some of the intrinsic limitations as well as the unique capabilities of this technique. The lack of sufficient understanding of DLS often leads to inappropriate experimental design and misinterpretation of the data. In this study, we performed DLS analyses on a series of citrate-stabilized AuNPs with diameters ranging from 10 to 100 nm. Our study shows that the measured hydrodynamic diameters of the AuNPs can vary significantly with concentration and incident laser power. The scattered light intensity of the AuNPs has a nearly sixth order power law increase with diameter, and the enormous scattered light intensity of AuNPs with diameters around or exceeding 80 nm causes a substantial multiple scattering effect in conventional DLS instruments. The effect leads to significant errors in the reported average hydrodynamic diameter of the AuNPs when the measurements are analyzed in the conventional way, without accounting for the multiple scattering. We present here some useful methods to obtain the accurate hydrodynamic size of the AuNPs using DLS. We also demonstrate and explain an extremely powerful aspect of DLS-its exceptional sensitivity in detecting gold nanoparticle aggregate formation, and the use of this unique capability for chemical and biological sensing applications.

Defining the ideal femtosecond laser capsulotomy.

PURPOSE: We define the ideal anterior capsulotomy through consideration of capsular histology and biomechanics. Desirable qualities include preventing posterior capsular opacification (PCO), maintaining effective lens position (ELP) and optimising capsular strength. METHODS: Laboratory study of capsular biomechanics and literature review of histology and published clinical results. RESULTS: Parameters of ideal capsulotomy construction include complete overlap of the intraocular lens to prevent PCO, centration on the clinical approximation of the optical axis of the lens to ensure concentricity with the capsule equator, and maximal capsular thickness at the capsulotomy edge to maintain integrity. CONCLUSIONS: Constructing the capsulotomy centred on the clinical approximation of the optical axis of the lens with diameter 5.25 mm optimises prevention of PCO, consistency of ELP and capsular strength.

Sealability of ultrashort-pulse laser and manually generated full-thickness clear corneal incisions.

PURPOSE: To compare the sealability and geometry of full-thickness clear corneal incisions (CCIs) created manually or with an ultrashort-pulse laser. SETTING: Lensar, Inc., Orlando, Florida, USA. DESIGN: Experimental study. METHODS: Ex vivo human donor globes were randomly assigned to groups for the manual or laser-generated full-thickness CCIs. Standard 3-plane manual or laser incisions were made in 22 globes. Incision geometry was measured using an optical coherence tomographer. Sealability was assessed by inflating globes to physiologic intraocular pressure (IOP) and pressing a mechanical plunger into the globe to deform the globe and increase IOP until leakage was detected using the Seidel test. The test of sealability at lowered IOP was performed similarly; the anterior chamber was monitored for signs of ingress of a povidone-iodine 10% solution placed externally. RESULTS: The mean IOP elevation at which leakage occurred was higher for the laser than for manually generated full-thickness CCIs, indicating that the mean sealability was better for the laser. However, t tests showed that there was no statistically significant difference in the mean IOP elevation at which full-thickness incision leakage occurred between manual and laser full-thickness CCIs. Thus, the sealability of the manual and laser full-thickness CCIs were equivalent for the incision geometry tested. The laser full-thickness CCIs were statistically closer to target geometry and showed less variability than the manual full-thickness CCIs. CONCLUSIONS: The sealability of laser and manual full-thickness CCIs were statistically equivalent. The laser full-thickness CCIs were more consistent in geometry and closer to the target incision geometry.

Endothelial cell loss with ultrashort-pulse laser and manually generated full-thickness clear corneal incisions.

PURPOSE: To compare the extent of corneal endothelial cell loss resulting from creating full-thickness clear corneal incisions manually using a diamond blade with that resulting from use of an ultrashort-pulse laser. SETTING: Lensar, Inc., Orlando, Florida, USA. DESIGN: Experimental study. METHODS: Ex vivo porcine globes were randomly assigned to groups for manual or laser-generated full-thickness CCIs. Standard 3-plane manual or laser incisions were made in freshly excised porcine globes. Two laser incision geometries were tested: with the exit incision perpendicular or 45 degrees to the posterior corneal surface. Corneas excised from the globe were measured immediately and after storage for 48 hours in Dulbecco modified Eagle media. Cell loss was assessed by measuring the area of damaged endothelial cells with a fluorescent microscope after cornea staining with a 3-component fluorescent live cell-dead cell assay. The percentage cell loss was expressed as the damaged area divided by the total area of a typical human corneal endothelium. RESULTS: Endothelial cell losses caused by manual and laser full-thickness CCIs were in the range of 0.8% to 1.4%. Although the mean endothelial cell loss percentages were lower for laser than for manual full-thickness CCIs, the measurements showed no statistically significant differences in the endothelial cell loss percentage between manual full-thickness CCIs and laser full-thickness CCIs with a perpendicular exit incision or 45-degree exit incision geometry. CONCLUSION: Ultrashort-pulse laser-generated full-thickness CCIs resulted in the statistically equivalent levels of corneal endothelial cell loss as full-thickness CCIs created by standard manual methods.

Impact of ablation efficiency reduction on post-surgery corneal asphericity: simulation of the laser refractive surgery with a flying spot laser beam.

We developed a rigorous simulation model to evaluate ablation algorithms and surgery outcomes in laser refractive surgery. The model (CASIM: Corneal Ablation SIMulator) simulates an entire surgical process, which includes calculating an ablation profile from measured wavefront errors, generating a shot pattern for a flying spot laser beam, simulation of the shot-by-shot ablation process based on a measured or modeled beam profile, and healing of the cornea after surgery. Using simulated post-surgery corneal shapes for various ablation parameters and beam fluences, we calculated angular dependence of ablation efficiency and the amount of increase in corneal asphericity. Without considering the effect of corneal healing, our result shows the following; 1) ablation efficiency reduction in the periphery depends on the peak fluence of the laser beam, 2) corneal asphericity increases even in the surgery using an ablation profile based on the exact Munnerlyn formula, contrary to previous reports, and 3) post-surgery corneal asphericity increases by a smaller amount in high fluence small Gaussian beam surgery than in low fluence truncated Gaussian beam. Our model can provide improved ablation profiles that compensate for the change of corneal asphericity and induction of spherical aberration in a flying spot laser system, resulting in better surgery outcomes in laser refractive surgeries.

Complications of cemented long-stem hip arthroplasties in metastatic bone disease.

UNLABELLED: It is controversial whether a cemented long-stem femoral arthroplasty is a safe surgical option for patients with meta-static bone disease of the hip. Cemented long stems increase the risk of embolic cascades and may cause subsequent cardiopulmonary complications, particularly in patients with metastatic disease. We retrospectively reviewed results of 29 long-stem cemented femoral arthroplasties in 27 patients in which surgical techniques that minimized intramedullary debris and canal pressurization were used. The surgical techniques minimized intraoperative cement-related emboli with aggressive medullary lavage, intraoperative canal suctioning during cementation, use of early low-viscosity polymethylmethacrylate, and slow, controlled insertion of the long-stem prosthesis. Cement-associated hypotension occurred in four (14%) patients, sympathomimetics were administered in nine (31%) patients, and a worsening mental status occurred postoperatively in one (3%) patient. There were no cement-associated desaturation events, cardiac arrests, or intraoperative deaths. No patients required prolonged intubation, and there were no postoperative cardiopulmonary events. Cemented long-stem femoral arthroplasty is a safe procedure for patients with high-risk metastatic disease. Increased awareness of cement-related cardiopulmonary pathophysiology, and modifying conventional surgical techniques can minimize cement-associated complications. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.