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Notes: A modified amplified spontaneous emission technique has been introduced to measure the radial distributions of the gain and the saturation energy density of the output of a double-discharge pulsed CuBr laser. An asymmetric distribution of the gain was obtained. With the laser tube temperature at 420 °C, the peak value of the gain and the saturation energy density are 70 db/m and 85 μJ/cm3, respectively.

Notes: For amplitude and phase response calibration of moving-coil electromagnetic geophones two parameters are needed, namely, the geophone natural frequency, f0, and the geophone upper resonance frequency fu. The phase-ellipse method is commonly used for the in situ determination of these parameters. For a given signal-to-noise ratio, the precision of the measurement off0 andfu depends on the phase sensitivity, f(δφ/δf) For some commercial geophones f(δφ/δf) atfu can be an order of magnitude less than the sensitivity atf0. In this paper we present an improved phase-ellipse method with increased precision. Compared to measurements made with the existing phase-ellipse methods, our method shows a 6- and 3-fold improvement in the precision, respectively, on measurements of f0 andfu on a commercial geophone.

Notes: Abstract Background: The literature contains few reports on negative outcomes after thoracoscopic spinal surgery. Methods: From November 1995 to February 1998, 90 patients underwent minimally invasive spinal surgery by thoracoscopic assistance as treatment for their anterior spinal lesions. The diagnoses included 41 spinal metastases, 13 cases of scoliosis, 12 burst fractures, 10 cases of tuberculous spondylitis, 8 cases of pyogenic spondylitis, 2 thoracic disc herniations, 2 cases of ankylosing spondylitis with discitis, 1 osteoporotic compression fracture, and 1 case of thoracolumbar kyphosis. The procedures included biopsy only (3 patients); thoracic discectomy (3 patients); multilevel anterior releases, discectomy, and fusion (14 patients); corpectomy for decompression (6 patients); corpectomy and interbody fusion (32) patients; and internal instrumentation (28 patients). Results: A total of 30 complications were noted in 22 patients (24.4%). Two fatal complications occurred, resulting from massive blood transfusion in one case and postoperative pneumonia in another. Other nonfatal complications included four cases of transient intercostal neuralgia, three superficial wound infections, three cases of pharyngeal pain, two cases of lung atelectasis, two cases of residual pneumothorax, two cases of subcutaneous emphysema, one inadvertent pericardial penetration due to adhesion, one chylothorax that resolved after conservative management, one vertebral screw malposition, and one graft dislodgement that needed late revision surgery. Three patients required ventilatory support for longer than 72 hours. Five patients with spinal metastases had an estimated intraoperative blood loss of more than 2,000 ml. No injury to the internal organs or spinal cord was observed. There were four conversions to open procedures due to two cases of severe pleural adhesions and two poorly tolerated one-lung ventilation. At the latest follow-up, nine patients had died as a result of cancer dissemination. Conclusions: (a) Well-selected patients and attention to details are essential to optimizing surgical results. (b) A refined technique for less invasive tumor surgery has been developed. (c) Surgeons had better experience with the standard anterior spinal approach and showed no hesitation in converting to an open procedure when necessary. A procedure failure does not mean a treatment failure.

Notes: Abstract Background: The standard open technique for exposure of the upper thoracic spine, T1–T4, usually requires a difficult thoracotomy. From November 1, 1995 to June 30, 1997, eight patients underwent video-assisted thoracoscopic spinal surgery in our institute to treat their upper thoracic spinal lesions endoscopically. Methods: A new approach, the so-called ``extended manipulating channel method,'' was used in this series that allows the combined use of video-assisted thoracoscopy and conventional spinal instruments to enter the chest cavity freely for the procedures. Patients' ages ranged from 44 to 89 years (average, 60 years). Definitive diagnoses included two pyogenic spondylitis and six spinal metastases. Five patients presented initially with myelopathy. Results: There were no deaths or neurologic injuries associated with this technique. The mean surgical time was 3.1 h. The mean duration of chest tube retention was 3.3 days. The mean total blood loss was 1,038 ml, and two patients had a blood loss of more than 2,000 ml owing to bleeding from epidural veins or raw osseous surfaces. Complications included one superficial wound infection and one subcutaneous emphysema that resolved spontaneously. In this series, there was no need of conversion to open thoracotomy for the patients. Conclusions: The thoracoscopy-assisted spinal technique using the extended manipulating channels, usually 2.5–3.5 cm, allows variable instrument angulations for manipulation. The mean surgical time (3.1 h) was considered no longer than for an open technique for the equivalent anterior procedure. Such an approach can achieve less procedure-related trauma and has proved to be a good alternative to other treatment modalities.

Notes: Abstract Background: The endoscopic treatment of spinal lesions in the thoracolumbar junction (T11–L2) poses a great challenge to the surgeon. From November 1, 1995 to December 31, 1996, we successfully used a combination of video-assisted thoracoscopy and conventional spinal instruments to treat 38 patients with anterior spinal lesions. Twelve of them had lesions in the thoracolumbar junction. Methods: The so-called extended manipulating channel method was used to perform vertebral biopsy, discectomy, decompressive corpectomy, interbody fusions, and/or internal fixations in these patients. The size of the thoracoscopic portals was greater than usual in order to allow conventional spinal instruments and a thoracoscope to enter the chest cavity freely and be manipulated by techniques similar to those used in standard open surgical procedures. In this series, the procedures were performed by using either a three-portal approach (2.5–3.5 cm) or a modified two-portal technique involving a 5–6 cm larger incision and a small one for introducing the scope. Results: None of the operations resulted in injury to the great vessels, internal organs, or spinal cord. The total time for the operation ranged from 1.5 to 4.5 h (average, 3); and the total blood loss ranged from 50 to 3000 cc (average, 1050). One patient was converted to an open procedure due to severe pleural adhesion. Complications included two instances of transient intercostal neuralgia, one superfical wound infection, and one residual pneumothorax. Conclusions: The video-assisted technique with the extended manipulating channel method presented in this report simplifies thoracoscopic spinal surgery in the thoracolumbar junction and makes it easier. It avoids division of the diaphragm, removal of the rib, and wide spread of the intercostal space, and it allows greater control of intraoperative vessel bleeding. Using this technique, the number of portals required during the procedure can be reduced. In addition, the technique reduces the endoscopic materials required, thus lowering overall cost. It is an effective and promising approach.

Notes: Abstract Background: Closure of ostium secundum atrial septal defect (ASD) vis median sternotomy (MS) is a simple procedure for most cardiac surgeons. Minimally invasive cardiac surgery (MICS) has recently been applied in the management of intracardiac lesions. Methods: We report our experience in surgical closure of isolated ASD via MICS in 60 patients and via MS in 58 patients. There was no difference between these two groups in gender, age, body weight, ratio of systemic to pulmonary blood flow, and pulmonary arterial pressure. Results: The duration of cardiopulmonary bypass was significantly longer in the MICS group than in the MS group [27 to 126 min (42 ± 12) and 14 to 158 min (27 ± 11), respectively; (p 〈 0.001]. However, the length of incision, incidence of temporary pacemaker wire insertion rate, duration of endotracheal intubation, timing of oral intake, postoperative day drainage amount, incidence of parenteral analgesic injection, postoperative length of stay, and return to normal activity interval were significant shorter and lower in patients of the MICS group than in those of the MS group. All the patients recovered rapidly from the surgery. Follow-up was complete in all patients, with no late complications and no residual shunt. Conclusion: Our results suggest that MICS is a good option for surgical closure of ASD.

Notes: Abstract Between November 1, 1995, and January 31, 1996, four separate thoracoscopic spinal fixation surgeries were performed via extended manipulating channels using the so-called three-portal technique. The diagnoses included three spinal metastases and one T11 burst fracture. All patients had myelopathy at presentation. Using the three-portal technique, the conventional spinal instruments and fixation devices could be passed freely through the extended manipulating channels (usually 3–4 cm) into the chest cavity and manipulated by techniques similar to those used in standard open procedures. A reduction-fixation spinal plate with variable screw and plate anchoring angles was successfully inserted in the procedures. The total length of the operation ranged from 3.5 to 5 h (average 4.3 h), and the total blood loss was 1000–2500 ml (average 1500 ml). There were no intraoperative deaths, and no patient showed neurological deterioration following the procedures. On the basis of these results, we believe that the combination of video-assisted thoracoscopy and conventional spinal instruments presented in this report would be an ideal method for performing these procedures. Throughout the operation, only one trocar was employed for introducing the thoracoscope. The thoracoports were used temporarily during tumor tissue retrievals. This technique makes thoracoscopy-assisted spinal fixation simple and easy. It allows greater control of intraoperative vessel bleeding and reduces the number of portals required during the procedure (on average to 3). In addition, the technique reduced the amount of endoscopic materials required for the procedure, thus reducing the cost of treatment.

Notes: Abstract Between November 1, 1995, and January 31, 1996, four separate thoracoscopic spinal fixation surgeries were performed via extended manipulating channels using the so-called three-portal technique. The diagnoses included three spinal metastases and one T11 burst fracture. All patients had myelopathy at presentation. Using the three-portal technique, the conventional spinal instruments and fixation devices could be passed freely through the extended manipulating channels (usually 3–4 cm) into the chest cavity and manipulated by techniques similar to those used in standard open procedures. A reduction-fixation spinal plate with variable screw and plate anchoring angles was successfully inserted in the procedures. The total length of the operation ranged from 3.5 to 5 h (average 4.3 h), and the total blood loss was 1000–2500 ml (average 1500 ml). There were no intraoperative deaths, and no patient showed neurological deterioration following the procedures. On the basis of these results, we believe that the combination of video-assisted thoracoscopy and conventional spinal instruments presented in this report would be an ideal method for performing these procedures. Throughout the operation, only one trocar was employed for introducing the thoracoscope. The thoracoports were used temporarily during tumor tissue retrievals. This technique makes thoracoscopy-assisted spinal fixation simple and easy. It allows greater control of intraoperative vessel bleeding and reduces the number of portals required during the procedure (on average to 3). In addition, the technique reduced the amount of endoscopic materials required for the procedure, thus reducing the cost of treatment.