Exploring the superfocusing performance of plasmonic lenses formed by coupled nanoslits

Micro & nano letters

article

Yechuan Zhu¹  Weizheng Yuan¹  Yiting Yu¹  Ping Wang¹  Hao Sun¹ 

[1] Key Laboratory of Micro/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University;Key Laboratory of Micro- and Nano-Electro-Mechanical Systems of Shaanxi Province, Northwestern Polytechnical University

关键词: plasmonics;    lenses;    nanostructured materials;    nanophotonics;    optical focusing;    geometrical optics;    holography;    phase modulation;    optical modulation;    finite difference time-domain analysis;    superfocusing performance;    plasmonic lenses;    coupled metallic nanoslits;    geometrical optics;    wavefront reconstruction principle;    phase modulation;    adjacent aperiodic nanoslits;    phase delay;    periodic metallic nanoslit theory;    finite-difference time-domain method;    lens size;    focal length;    working medium;    incident wavelength;   

DOI  :  10.1049/mnl.2016.0288

学科分类：计算机科学（综合）

来源: Wiley

【 摘 要 】

Although spinal anesthesia (SA) in a parturient with kyphoscoliosis is not only a challenge to give but also may fail most of the times or produce patchy effect. We report the successful use of isobaric ropivacaine in SA after unilateral patchy effect of intrathecal hyperbaric bupivacaine in kyposcoliotic pregnant patient for surgery. A 24 year old female, primigravida with 36 week gestation in labor was admitted for cesarean section due to cephalopelvic disproportion. She had severe kypohoscoliosis of lower thoracolumbar spine due to poliomyelitis of lower limbs. On physical examination, interspinous lumbar spaces were not felt appreciably. X-ray spine showed severe kyphoscoliosis of lower thoracolumbar spine with convexity toward left. After obtaining normal routine investigations, surgery was planned under SA. Under all aseptic condition in sitting position, 12 mg of 0.5% hyperbaric bupivacaine was given after free flow of CSF in L3-L4 subarachnoid space with 25 G spinal needle by paramedian approach. Immediately patient placed in supine position and anesthetic level checked with pinprick method. On right side, level achieved up to T6 in comparison to T12 on left side after 5 minutes. Immediately 15-20 degree left side table tilt given to achieve effect on left side. But in view of incomplete anesthetic level on left side even after 20 min, repeat SA with 8 mg of isobaric ropivacaine 0.5% was given at L3-L4 level in sitting position. Within 5 minutes of repeat spinal, adequate sensory block up to T4 achieved on both sides in supine position and surgery started. Patient remained hemodynamically stable throughout surgery. During postoperative period, patient was observed for any postoperative and spinal related complication which was found uneventful. Anesthetic management in pregnant patient with kyphoscoliosis is always challenging because of anatomical and physiological respiratory changes produced by abnormal spine curve. Increase in cardiac output during normal pregnancy is poorly tolerated by these patients because of increased peripheral vascular resistance. These cardiopulmonary changeswhich were absent in our patients, place the patients at increased risk of morbidity and requirement of postoperative ventilation.1,2 Although use of both general and regional anesthesia have been described in these patients but SA was preferred here to avoid airway manipulation in setting of difficult airway and full stomach associated with pregnancy. To overcome technical difficulty with regional anesthesia, different approaches have been described like paramedian approach by Haung.3 In our case we also used paramedian approach and luckily we got spinal puncture in 2nd attempt both times. Main disadvantage of regional anesthesia in these patients are incomplete or failed block which has also occurred in our patient.4 The cause of incomplete block could be the spine deformity itself or incorrect placement of local anesthetic, and drug defects. But in our case likely cause was due to the early settlement of hyperbaric drug on right side due to abnormal spine curve. So to achieve complete block and to counter the postural gravity effect on hyperbaric drug, we used isobaric ropivacaine during repeat SA.To prevent high spinal complications, low dose was used in repeat spinal. Incomplete block with use of hyperbaric local anesthetic drug in kyphoscoliotic patient has been previously reported but still clinical reporting regarding successful use of isobaric drug in these patients is needed.5 In conclusion, isobaric local anesthetic drug should be preferred over hyperbaric drug for successful spinal anesthesia in patient with severe kyphoscoliosis.

【 授权许可】

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