RESUMEN
SETTING: High mortality and high transmission rates of extensively drug-resistant tuberculosis (XDR-TB) in KwaZulu-Natal Province of South Africa have highlighted the role of hospitals in the spread of TB and drug-resistant TB. OBJECTIVES: To determine the operational effectiveness of the National TB Programme (NTP) at a regional/district hospital and its referral clinics. DESIGN: In this multi-faceted retrospective case study, a framework was developed to evaluate the different components of the TB services, their performance in relation to each other and the system as a whole. Different methods used included structured and semi-structured interviews, retrospective medical record reviews and retrospective register reviews. RESULTS: Only 18% of those diagnosed with smear-positive pulmonary TB (PTB) in the hospital laboratory completed their treatment and 11% were cured. Clinicians did not adhere to the diagnostic guidelines of the NTP. In the TB register, 85% of PTB cases were diagnosed in the absence of sputum microscopy. Chest X-rays alone were used to diagnose PTB in 45% of the records reviewed. In addition, clinicians failed to document a clinical history suggestive of TB. Only 66 (29%) of the hospital's 225 smear-positive PTB patients reached the clinics for completion of their treatment. CONCLUSION: System failures, together with inadequate knowledge and understanding of clinicians, undermined the effectiveness of the NTP. A reduction in TB and drug-resistant forms of TB is dependent on effective diagnosis, treatment and improved communication systems between the hospital, laboratory and its down-referral clinics.
Asunto(s)
Atención a la Salud/organización & administración , Tuberculosis Extensivamente Resistente a Drogas/tratamiento farmacológico , Programas Nacionales de Salud/organización & administración , Derivación y Consulta/organización & administración , Antituberculosos/uso terapéutico , Tuberculosis Extensivamente Resistente a Drogas/diagnóstico , Conocimientos, Actitudes y Práctica en Salud , Humanos , Registros Médicos , Investigación Operativa , Pacientes Desistentes del Tratamiento , Derivación y Consulta/estadística & datos numéricos , Sistema de Registros , Estudios Retrospectivos , Sudáfrica , Tuberculosis Resistente a Múltiples Medicamentos/diagnóstico , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológicoRESUMEN
We report on an investigation of the trapezoidal design and fabrication defects in phase masks used to produce Bragg reflection gratings in optical fibers. We used a direct visualization technique to examine the nonuniformity of the interference patterns generated by several phase masks. Fringe patterns from the phase masks are compared with the analogous patterns resulting from two-beam interference. Atomic force microscope imaging of the actual phase gratings that give rise to anomalous fringe patterns is used to determine input parameters for a general theoretical model. Phase masks with pitches of 0.566 and 1.059 microm are modeled and investigated.