A preliminary evaluation of optometric management and referral protocols for pa-tients with diabetic retinopathy

Aim: The purpose of this pilot study was to investigate  the  assessment,  management  and referral practices of South African optometrists in  the  care  of  patients  with  diabetic  retinop-athy  (DR)  and  to  recommend  strategies  to improve  and  standardize  patient  management as required.  Methods:  The  study  design  incorporated quantitative,  qualitative  and  clinical  measures that were administered to fourteen experienced optometrists from the Durban area. The quan-titative measure, the questionnaire in appendix I, evaluated the optometrists’ management pro-tocols of patients with diabetes mellitus (DM).  These  included  the  optometrists’  referral  and co-management practices, their awareness and usage  of  appropriate  guidelines  in  the  man-agement  and  referral  of  these  patients,  their perceived levels of competence and confidence in their education, levels of service offered to the patients and finally the role of Continuous Professional  Development  (CPD).  This  self-report information was supplemented by a set of clinical measures where the study sample grad-ed levels of DR, chose appropriate management options  and  indicated  prognosis  for  disease progression based on a set of slides presented to  them.  Finally  the  fourteen  optometrists,  as well as two ophthalmologists, were interviewed using tailored, semi-structured interview sched-ules. These interviews were used to elaborate and corroborate information obtained from the other two research approaches.  Results:  Descriptive  analysis  was  used  to analyse  the  data  from  the  quantitative  and clinical  measures,  whilst  the  interviews  were analysed  thematically.  Although  86%  of  the sample routinely screened for ocular manifesta-tions of DM, there was no standardization in the criteria used by the fourteen optometrists. Only  15%  of  the  sample  reportedly  assessed their  patients  using  dilated  fundus  examina-tions  (DFE),  which  is  the  internationally  rec-ommended standard of care. The results of the clinical measures indicated that there was a lack of standardization in the management and refer-ral of patients with DR by the study sample, contrary  to  their  own  levels  of  confidence  in their  educational  competencies  regarding  DR and their perception of the level of service that they  offered  to  their  patients.  The  interviews with the optometrists provided crucial insights into this lack of standardised care of patients with DR, with the ophthalmologists confirming the  urgent  need  for  CPD  aimed  at  enhancing clinical  skills  and  ensuring  standardization  in the  management  and  referral  of  patients  with DR.  This finding was particularly relevant for co-management models.Conclusion: This  pilot  study  indicates  that the  performance  of  the  optometrists  (albeit  a relatively small group) in the assessment, man-agement and referral of patients with DR was inconsistent  and  not  in  keeping  with  interna-tionally recommended guidelines. It is recom-mended  that  CPD  programmes  focus  on  the improvement of clinical skills and on the imple-mentation of existing standardised management protocols  for  patients  with  DR.  This  should result in improved patient care, patient confi-dence and loyalty with regard to care received, efficient and effective models of management and  co-management  and  decreased  costs  to patients and the health care system.

Techniques in Cardiology : PDA Closure in Children

BACKGROUND

Transcatheter closure of patent ductus arteriosus (PDA) with various devices has been evaluated worldwide and in selected cases can be performed successfully, thus avoiding the morbidity associated with surgical closure.

METHODS AND RESULTS

A 2 year old female child presented with PDA and aortic angiography showed large PDA (tubular). This defect can be closed nonsurgically by coils and devices. The coil used are normally 0.038" having delivery system called Flipper, but this child had a large PDA and so was closed by thicker coil 0.052" using a coil-Bioptome-sheath system, which is the first reported case from the Armed Forces.

CONCLUSIONS

We report the initial experience at our center of closure of PDA with a new coil-Bioptome-sheath system.

Relationship of proximal fixation to renal dysfunction in patients undergoing endovascular aneurysm repair

Technological advancements have lead to dramatic improvements in stentgraft device design resulting in more trackable delivery systems and transrenal uncovered stents and barbs for better fixation. Transrenal bare-stents may limit stentgraft migration, particularly in patients with short or flared proximal aortic necks. However, potential disadvantages might be in worsening renal function, particularly in patients with preexisting renal insufficiency. We retrospectively analyzed our recent 7 year experience of patients undergoing endovascular aneurysm repair (EVAR) using a variety of stentgrafts with and without transrenal bare-stent fixation. Patients were divided into 2 groups; infrarenal fixation (IRF) vs transrenal fixation (TRF), or patients with preoperative serum Cr values that were normal (= or <1.5 mg/dl) vs slightly elevated (1.6-2 mg/dl), vs markedly elevated (2.1- 3.5 mg/dl). The exclusion criteria included patients with chronic renal insufficiency (CRI) on hemodialysis, and preoperative high-grade renal artery stenoses requiring angioplasty and stenting. Of 705 patients that underwent EVAR, 496 (IRF: 385 [78%], and TRF: 111 [22%]) were available with routine evaluations of serum Cr and CT scans. Preexisting comorbidities, mean procedure contrast volume, and postprocedure follow-up were similar in both groups. In the immediate postoperative period, mean serum Cr did not change significantly in either the IRF group (1.3+/-0.7 mg/dl to 1.2+/-0.9 mg/dl) or the TRF group (1.3+/-0.5 mg/dl to 1.3+/-0.6 mg/dl). Mean serum Cr did, however, significantly increase over longer follow-up in both groups: 1.4+/-0.8 mg/dl for IRF (P<0.03), and 1.5 +/- 0.8 mg/dl for TRF (P<0.01). Cr clearance was similarly unchanged in the immediate postoperative period (58+/-23 to 61+/-25 ml/min/1.73 m2 for IRF group, 53+/-17 to 55+/-17 ml/min/1.73 m2 for TRF group), but was significantly decreased in longer follow-up (53+/-23 ml/min/1.73 m2 for IRF, p<0.02: and 48+/-16 ml/min/1.73 m2 for TRF, P<0.01). There were no significant differences in serum Cr increase (p=0.19) or Cr clearance decrease (p=0.68) between the IRF and TRF groups. Small renal infarcts were noted in 6 patients (1.6%) in the IRF group, and in 8 patients (7%) in the TRF group (p=0.37). Of patients with normal preoperative renal function, renal dysfunction developed in 7.7% of IRF group and 6.1% of TRF group (p=0.76). In patients with preexisting CRI, renal dysfunction developed in 18.2% of IRF group, and 17.1% of TRF group (p=0.95). Eight patients with postoperative renal dysfunction, 5 (1.3%) from IRF group and 3 (2.7%) from TRF group subsequently required hemodialysis, and this difference was not statistically significant (p=0.91). We also analyzed 200 consecutive patients undergoing EVAR with intra-arterial contrast agents with and without preexisting CRI not on dialysis. The groups were identified on the basis of preprocedure serum Cr: group 1 (n=108), Cr less than 1.5 mg/dL (normal range); group 2 (n=65), Cr 1.5 to 2.0 mg/dL; group 3 (n=27), Cr 2.1 to 3.5 mg/dL. Routine precautions in patients with CRI included preoperative intravenous hydration with 2 L of normal saline solution, discontinuation of all nephrotoxic drugs, intraoperative administration of mannitol (0.5 g/kg intravenously), and use of nonionic, low osmolar intra-arterial contrast agent (Omnipaque 350). One-hundred and eight patients had normal renal function (group 1), and 92 patients had preexisting CRI with baseline Cr 1.5 to 2.0 mg/dL (group 2, n=65) or 2.1 to 3.5 mg/dL (group 3, n=27). Comorbid conditions included coronary artery disease (group 1, 51%; group 2, 49%; group 3, 59%), hypertension (group 1, 39%; group 2, 46%; group 3, 52%), and diabetes mellitus (group 1, 25%; group 2, 35%; group 3, 48%). In groups 1, 2, and 3, the mean volume of low osmolar contrast agent used was 210 cc, 160 cc, 130 cc, respectively; hemodynamic instability developed in 3, 1, and 1 patient, respectively. The incidence of postoperative complications between the 3 study groups was not statistically different. In grications between the 3 study groups was not statistically different. In group 1 a transient increase in serum Cr (>30% over baseline and >1.4 mg/dL) was noted in 3 patients (2.7%), 2 of whom (1.9%) required temporary hemodialysis and 1 (0.9%) who died of renal failure. In group 2 a transient increase in serum Cr was noted in 2 patients (3.1%); both patients (3.1%) required temporary hemodialysis, and 1 patient (1.5%) died of renal failure. In group 3 a transient increase in serum Cr was noted in 2 patients (7.4%); 1 patient (3.7%) required temporary hemodialysis, and 1 patient (3.7%) died of renal failure. Perioperative hypotension significantly increased the risk for elevated serum Cr and death (p<0.05), and larger contrast volume was associated with an increase in serum Cr (p<0.05) during the postoperative period. Following EVAR renal function declines slightly with both IRF and TRF. Our data show no overall difference between patients with IRF and TRF with respect to infarcts, decline in renal function, or onset of dialysis. There were a slightly greater number of renal infarcts in the TRF group, but these infarcts were clinically inconsequential. In patients with CRI, EVAR with intra-arterial radiographic contrast agents is believed to impair renal function, and CRI is considered a relative contraindication to the procedure. Results of our investigation indicate that risk for worsening renal insufficiency, dialysis, and death is only slightly and not significantly greater in patients with CRI compared with patients with normal renal function. With appropriate precautions of avoiding perioperative hypotension and limiting the volume of nonionic contrast agents, CRI need not be a contraindication for EVAR with intra-arterial contrast agents.

Structural studies of biomaterials using double-quantum solid-state NMR spectroscopy

Proteins directly control the nucleation and growth of biominerals, but the details of molecular recognition at the protein-biomineral interface remain poorly understood. The elucidation of recognition mechanisms at this interface may provide design principles for advanced materials development in medical and ceramic composites technologies. Here, we describe both the theory and practice of double-quantum solid-state NMR (ssNMR) structure-determination techniques, as they are used to determine the secondary structures of surface-adsorbed peptides and proteins. In particular, we have used ssNMR dipolar techniques to provide the first high-resolution structural and dynamic characterization of a hydrated biomineralization protein, salivary statherin, adsorbed to its biologically relevant hydroxyapatite (HAP) surface. Here, we also review NMR data on peptides designed to adsorb from aqueous solutions onto highly porous hydrophobic surfaces with specific helical secondary structures. The adsorption or covalent attachment of biological macromolecules onto polymer materials to improve their biocompatibility has been pursued using a variety of approaches, but key to understanding their efficacy is the verification of the structure and dynamics of the immobilized biomolecules using double-quantum ssNMR spectroscopy.

Semiclassical theory of spin-orbit interactions using spin coherent states

We formulate a semiclassical theory for systems with spin-orbit interactions. Using spin coherent states, we start from the path integral in an extended phase space, formulate the classical dynamics of the coupled orbital and spin degrees of freedom, and calculate the ingredients of Gutzwiller's trace formula for the density of states. For a two-dimensional quantum dot with a spin-orbit interaction of Rashba type, we obtain satisfactory agreement with fully quantum-mechanical calculations. The mode-conversion problem, which arose in an earlier semiclassical approach, has hereby been overcome.