Evaluation of the Rebound Hernia Repair Device for Laparoscopic Hernia Repair

Background:

The characteristics of the ideal type of mesh are still being debated. Mesh shrinkage and fixation have been associated with complications. Avoiding shrinkage and fixation would improve hernia recurrence rates and complications. To our knowledge, this is the first study of a device with a self-expanding frame for laparoscopic hernia repair.

Methods:

Six Rebound Hernia Repair Devices were placed laparoscopically in pigs. This device is a condensed polypropylene, super-thin, lightweight, macro-porous mesh with a self-expanding Nitinol frame. The devices were assessed for adhesions, shrinkage, and histological examination. Laboratory and radiologic evaluations were also performed.

Results:

The handling properties of the devices facilitated their laparoscopic placement. They were easily identified with simple x-rays. The mesh was firmly integrated within the surrounding tissue. One device was associated with 3 small adhesions. The other 5 HRDs had no adhesions. We noted no shrinkage or folding. All devices preserved their original size and shape.

Conclusions:

At this evaluation stage, we found that the Rebound Hernia Repair Device may serve for laparoscopic hernia repair and has favorable handling properties. It prevents folding and shrinkage of the mesh. It may eliminate the need for fixation, thus preventing chronic pain. The Nitinol frame also allowed radiologic evaluation for gross movement. Further studies will be needed to evaluate its clinical application.     

Predictors of very low adherence with medications for osteoporosis: towards development of a clinical prediction rule

Summary  

We developed a clinical prediction rule score to predict medication non-adherence for women prescribed osteoporosis treatment. When combined into a summative score, 62% with seven or more points on the score demonstrated very low adherence. This compares with 17% subjects with fewer than seven points (c-statistic = 0.74).     

Cardiovascular simulator improvement: pressure versus volume loop assessment

This article presents improvement on a physical cardiovascular simulator (PCS) system. Intraventricular pressure versus intraventricular volume (PxV) loop was obtained to evaluate performance of a pulsatile chamber mimicking the human left ventricle. PxV loop shows heart contractility and is normally used to evaluate heart performance. In many heart diseases, the stroke volume decreases because of low heart contractility. This pathological situation must be simulated by the PCS in order to evaluate the assistance provided by a ventricular assist device (VAD). The PCS system is automatically controlled by a computer and is an auxiliary tool for VAD control strategies development. This PCS system is according to a Windkessel model where lumped parameters are used for cardiovascular system analysis. Peripheral resistance, arteries compliance, and fluid inertance are simulated. The simulator has an actuator with a roller screw and brushless direct current motor, and the stroke volume is regulated by the actuator displacement. Internal pressure and volume measurements are monitored to obtain the PxV loop. Left chamber internal pressure is directly obtained by pressure transducer; however, internal volume has been obtained indirectly by using a linear variable differential transformer, which senses the diaphragm displacement. Correlations between the internal volume and diaphragm position are made. LabVIEW integrates these signals and shows the pressure versus internal volume loop. The results that have been obtained from the PCS system show PxV loops at different ventricle elastances, making possible the simulation of pathological situations. A preliminary test with a pulsatile VAD attached to PCS system was made.     

Magnetic suspension of the rotor of a ventricular assist device of mixed flow type

Abstract:  This work presents results of preliminary studies concerning application of magnetic bearing in a ventricular assist device (VAD) being developed by Dante Pazzanese Institute of Cardiology—IDPC (São Paulo, Brazil). The VAD-IDPC has a novel architecture that distinguishes from other known VADs. In this, the rotor has a conical geometry with spiral impellers, showing characteristics that are intermediate between a centrifugal VAD and an axial VAD. The effectiveness of this new type of blood pumping principle was showed by tests and by using it in heart surgery for external blood circulation. However, the developed VAD uses a combination of ball bearings and mechanical seals, limiting the life for some 10 h, making impossible its long-term use or its use as an implantable VAD. As a part of development of an implantable VAD, this work aims at the replacement of ball bearings by a magnetic bearing. The most important magnetic bearing principles are studied and the magnetic bearing developed by Escola Politécnica of São Paulo University (EPUSP-MB) is elected because of its very simple architecture. Besides presenting the principle of the EPUSP-MB, this work presents one possible alternative for applying the EPUSP-MB in the IDPC-VAD.     

Living donor liver transplantation in children: Should the adult donor be operated on by an adult or pediatric surgeon? Experience of a single pediatric center

Background/Purpose

Living donor liver transplantation has become a cornerstone for the treatment of children with end-stage hepatic dysfunction, especially within populations or countries with low rates of organ utilization from deceased donors. The objective is to report our experience with 185 living donors operated on by a team pediatric surgeons in a tertiary center for pediatric liver transplantation.

Methods

Retrospective analysis of medical records of donors of hepatic grafts for transplant undergoing surgery between June 1998 and March 2013.

Results

Over the last 14 years, 185 liver transplants were performed in pediatric recipients of grafts from living donors. Among the donors, 166 left lateral segments (89.7%), 18 left lobes without the caudate lobe (9.7%) and 1 right lobe (0.5%) were harvested. The donor age ranged from 16 to 53 years, and the weight ranged from 47 to 106 kg. In 10 donors, an additional graft of the donor inferior mesenteric vein was harvested to substitute for a hypoplastic recipient portal vein. The transfusion of blood products was required in 15 donors (8.1%). The mean hospital stay was 5 days. No deaths occurred, but complications were identified in 23 patients (12.4%): 9 patients experienced abdominal pain and severe gastrointestinal symptoms and 3 patients required reoperations. Eight donors presented with minor bile leaks that were treated conservatively, and 3 patients developed extra-peritoneal infections (1 wound collection, 1 phlebitis and 1 pneumonia). Eight grafts (4.3%) showed primary dysfunction resulting in recipient death (3 cases of fulminant hepatitis, 1 patient with metabolic disease, 1 patient with Alagille syndrome and 3 cases of biliary atresia in infants under 1 year old). There was no relation between donor complications and primary graft dysfunction (P = 0.6).

Conclusions

Living donor transplantation is safe for the donor and presents a low morbidity. The donor surgery may be performed by a team of trained pediatric surgeons.     

Cephalometric evaluation of the pharyngeal airway space after orthognathic surgery and distraction osteogenesis of the jaw bones

Objective:

Orthognathic surgeries and distraction osteogenesis (DO) of the jaw bones cause a change in the pharyngeal airway space (PAS). The aim of our study was to evaluate the magnitude of changes occurring in the pharyngeal airway after mandibular set-back surgeries and DO of maxilla/mandible.

Materials and Methods:

The study undertaken was a retrospective cephalometric study. Subjects included in our study had undergone mandibular set-back surgery or DO of maxilla/mandible. Lateral cephalograms of the subjects taken pre-operatively (T0), immediate post-operatively (T1) and after a minimum follow-up period of 6 months (T2) were studied. The cephalograms were traced manually and the following parameters were evaluated: Surface area of the PAS, pharyngeal airway width at the level of the base of the tongue, position of the hyoid bone and the tongue. Repeated measure ANOVA test was done to assess the presence of any significant changes in the proposed parameters at T0, T1 and T2. A correlation analysis was made between the mandibular/maxillary movements and the corresponding changes in the PAS.

Results:

Surgical movements of maxilla and mandible do have an effect on the pharyngeal airway.

Conclusion:

It was clearly evident that the effects of mandibular movements on the PAS and the hyoid bone is more significant than the maxillary movements.KEY WORDS: Distraction osteogenesis, orthognathic surgery, pharyngeal airway space     

Down-regulation of Na+ transporters and AQP2 is responsible for acyclovir-induced polyuria and hypophosphatemia

BACKGROUND: Acyclovir (ACY) is a useful therapeutic agent for the systemic treatment of herpes virus infection. An increase in urinary phosphate excretion and polyuria has been described. The objective of this study was to analyze the exact mechanism of the urinary-concentrating dysfunction and the increase in phosphaturia associated with ACY. METHODS: We first analyzed 7 (adult and pediatric) non-AIDS cases of encephalitis receiving 15 mg/kg bw/d of intravenous ACY. Fractional phosphate and sodium excretion, urinary potassium volume, and plasma phosphate concentrations were analyzed. Additional studies in rats treated with intraperitoneal ACY (100 mg/kg bw) were also conducted. Animals were maintained in metabolic cages and 24-hour urine samples were collected to measure volume, osmolality, and sodium/potassium/phosphate excretion. Treated rats were also evaluated after 24 hours and 48 hours of water deprivation. Northern hybridization and semiquantitative immunoblotting were performed to evaluate (in both control and treated animals) expression of the cotransporters Na-Pi type IIa (Na-Pi-IIa) and Na-K-2Cl (NKCC2). Semiquantitative immunoblotting was carried out in the kidneys of ACY rats and control rats in order to analyze aquaporin 2 (AQP2) protein expression. RESULTS: Patients started on ACY developed polyuria and hyperphosphatemia after 48 hours. In rats, ACY-induced hyperphosphaturia and hypophosphatemia were accompanied by increased excretion of sodium, potassium, and magnesium, increased urine output, lower urinary osmolality, and a partial urinary concentrating defect. Concurrent downregulation of Na-Pi-IIa and NKCC2 expression was observed. There was also a decrease in medullar expression of the AQP2 collecting duct water channel. CONCLUSION: Downregulation of Na-Pi-IIa appears to play a crucial role in the downregulation of ACY-induced hyperphosphaturia. The accompanying polyuria and urinary-concentrating defect can in part be explained by the downregulation of NKCC2 and AQP2.