Development of a computer-assisted high-pressure Injection device for vertebroplasty

A novel computer-assisted injection device for the delivery of highly viscous bone cements in vertebroplasty is presented. It addresses the shortcomings of manual injection systems ranging from low-pressure and poor level of control to device failure. The presented instrument is capable of generating a maximum pressure of 5000 kPa in traditional 6-ml syringes and provides an advanced control interface for precise cement delivery from outside radiation fields emitted by intraoperative imaging systems. The integrated real-time monitoring of injection parameters, such as flow-rate, volume, pressure, and viscosity, simplifies consistent documentation of interventions and establishes a basis for the identification of safe injection protocols on the longer term. Control algorithms prevent device failure due to overloading and provide means to immediately stop cement flow to avoid leakage into adjacent tissues.

Effect of varying injection rates of a saline chaser on aortic enhancement in CT angiography: phantom study

The effect of varying injection rates of a saline chaser on aortic enhancement in computed tomography (CT) angiography was determined. Single-level, dynamic CT images of a physiological flow phantom were acquired between 0 and 50 s after initiation of contrast medium injection. Four injection protocols were applied with identical contrast medium administration (150 ml injected at 5 ml/s). For baseline protocol A, no saline chaser was applied. For protocols B, C, and D, 50 ml of saline was injected at 2.5 ml/s, 5 ml/s, and 10 ml/s, respectively. Injecting the saline chaser at twice the rate as the contrast medium yielded significantly higher peak aortic enhancement values than injecting the saline at half or at the same rate as the contrast medium (P < 0.05). Average peak aortic enhancement (HU) measured 214, 214, 218, and 226 for protocols A, B, C, and D, respectively. The slower the saline-chaser injection rate, the longer the duration of 90% peak enhancement: 13.6, 12.2, and 11.7 s for protocols B, C, and D, respectively (P > 0.05). In CT angiography, saline chaser injected at twice the rate as the contrast medium leads to increased peak aortic enhancement and saline chaser injected at half the rate tends towards prolonging peak aortic enhancement plateau.

Off-pump extraanatomic aortic bypass for the treatment of complex aortic coarctation and hypoplastic aortic arch

BACKGROUND: Despite advances in surgical and interventional techniques, the optimal surgical treatment of severe aortic (re) coarctation and hypoplastic aortic arch is still controversial. Anatomic repair may require extensive dissection, cardiopulmonary bypass, and deep hypothermic circulatory arrest with their inherent risks. The aim of this study was to analyze the outcome of off-pump extraanatomic aortic bypass as a surgical alternative to local repair. METHODS: From February 2000 to December 2005, ten consecutive patients (median age 20 years; range, 11 to 38 years) with severe aortic (re) coarctation (n = 4) and (or) hypoplastic aortic arch (n = 7) underwent off-pump extraanatomic aortic bypass through median sternotomy. All but three patients had undergone previous surgery for coarctation and angioplasty or stenting. Three patients underwent concomitant replacement of the ascending aorta because of an aneurysm using cardiopulmonary bypass. RESULTS: Postoperative hospital course was uneventful in all patients. There was no perioperative mortality or significant morbidity. During a mean follow-up of 48 +/- 22 months no patient required additional procedures. All patients were free of symptoms; no patient showed signs of heart failure after follow-up. At last follow-up, no patient presented with claudication, nor any patient experienced orthostatic problems due to a steal phenomenon. During follow-up, hypertension resolved in all patients with residual mild hypertension in two patients. CONCLUSIONS: Off-pump extraanatomic aortic bypass is an attractive treatment option for complex aortic (re) coarctation and hypoplastic aortic arch. Perioperative risks are minimized, hypertension is influenced favorably, and midterm survival is event-free.

The effect of pulsed jet lavage in vertebroplasty on injection forces of polymethylmethacrylate bone cement, material distribution, and potential fat embolism: a cadaver study

STUDY DESIGN: In vitro testing of vertebroplasty techniques including pulsed jet-lavage for fat and marrow removal in human cadaveric lumbar and thoracic vertebrae. OBJECTIVE: To develop jet-lavage techniques for vertebroplasty and investigate their effect on cement distribution, injection forces, and fat embolism. SUMMARY OF BACKGROUND DATA: The main complications of cement vertebroplasty are cement leakage and pulmonary fat embolism, which can have fatal consequences and are difficult to prevent reliably by current vertebroplasty techniques. METHODS: Twenty-four vertebrae (Th8-L04) from 5 osteoporotic cadaver spines were grouped in triplets depending on bone mineral density (BMD). Before polymethylmethacrylate (PMMA) vertebroplasty, a pulsatile jet-lavage for removal of intertrabecular fat and bone marrow was performed in 2 groups with 8 specimens each, performing radial and axial irrigation from the biopsy needles. One hundred mL of Ringer solution were injected through 1 pedicle and regained by low vacuum via the contralateral pedicle. Eight control vertebrae were not irrigated. All specimens underwent standardized PMMA cement augmentation injecting 20% of the vertebral volume. Injection forces, cement distribution, and extravasations were quantified. RESULTS: All irrigation solution could be retrieved with the vacuum applied. A Kruskal-Wallis test revealed significantly higher injection forces of the control group as compared with the irrigated groups (P = 0.021). Dilatation of the syringe at forces above 300 N occurred in 75% of the untreated compared with 12.5% of the lavaged specimens. CT distribution analysis showed more homogenous cement distribution of the cement and significantly less extravasation in the irrigated specimens. CONCLUSION: The developed lavage technique for vertebroplasty showed to be feasible and reproducible. The reduction of injection forces would allow the use of more viscous PMMA cement lowering the risk for cement embolization and results in a safer procedure. The wash-out of bone marrow and the possible reduction of pulmonary fat embolism have to be verified with in vivo models.

Prevention of delayed cerebral vasospasm by continuous intrathecal infusion of glyceroltrinitrate and nimodipine in the rabbit model in vivo

OBJECTIVE: Intrathecal bolus administration of nitric oxide donors and calcium channel antagonists has been proposed to reduce cerebral vasospasm (CVS) in animal subarachnoid hemorrhage (SAH) models. Intrathecal continuous administration of these substances for CVS prevention has not been extensively evaluated. This study compared the efficacy of continuous intrathecal infusions of the NO donor glyceroltrinitrate and nimodipine in preventing delayed CVS associated with SAH in an animal model in vivo. METHODS: New Zealand White rabbits were randomly assigned to six groups: no SAH/NaCl, no SAH/NO, no SAH/nimodipine, SAH/NaCl, SAH/NO, or SAH/nimodipine. Glyceroltrinitrate (GTN) at 0.5 microg/microl (0.5 microl/h) or nimodipine at 0.2 microg/microl (10 microl/h) or NaCl was continuously infused into the cisterna magna via an Alzet osmotic pump from day 0 to day 5 after injection of 1.0 ml autologous blood. The magnitude of spasm in the basilar artery was determined by comparison of pre- and posttreatment angiography and was calculated as proportional change in intraluminal diameter based on automatic measurements. RESULTS: A total of 55 experiments and 110 angiograms were performed. SAH was associated with vasoconstriction of the basilar artery (SAH/NaCl group 19.85+/-2.94%). Continuous intrathecal injection of GTN and nimodipine prevented SAH-induced CVS. There was significant prevention of CVS in animals treated with GTN (SAH/NO group 5.93+/-5.2%, n=11) and nimodipine (SAH/nimodipine group: 0.55+/-2.66%, n=9). There was no significant difference between the treatment groups and controls in prevention of CVS. CONCLUSIONS: This study demonstrates that prophylactic continuous intrathecal administration of either GTN or nimodipine equally prevents SAH-associated CVS in an animal model.

The use of polydimethylsiloxane for injection laryngoplasty

BACKGROUND: Injuries of the recurrent laryngeal nerve with consecutive vocal cord paralysis is a typical complication in chest, esophageal, thyroideal, and neck surgery. Glottic insufficiency secondary to such a lesion can be treated by endolaryngeal vocal cord augmentation (injection laryngoplasty). Many different substances have been used, often showing complications or disadvantages. This study reports on the use of injectable polydimethylsiloxane (PDMS), with special regard to the long-term results. METHODS: In this prospective study, 21 patients with unilateral vocal cord paralysis underwent injection laryngoplasty using PDMS at a volume of 0.5-1.0 ml. Preoperatively, 6 weeks and 12 months after the injection the following parameters concerning patients' voice were evaluated: Glottic closure by videolaryngostroboscopy, maximum phonation time, voice range, voice dynamic, jitter, shimmer, noise-to-harmonic-ratio, and roughness, breathiness, and hoarseness (RBH). In addition, patients were asked to give their own evaluation of how satisfied they felt with their voice and of the handicaps it caused them. RESULTS: Postoperatively an improvement was evident in all the parameters that were investigated, and this significant improvement was still in evidence for most of the parameters more than one year after the injection. In our study no complications were observed more than one year after injection. CONCLUSION: PDMS is a safe substance for injection laryngoplasty in unilateral vocal cord paresis. Objective and subjective parameters confirm its effectiveness. It is suitable for obtaining satisfying results in the reestablishment of the patient's voice and communication ability.

Serum hyperglycosylated human chorionic gonadotropin to predict the gestational outcome in in vitro fertilization/intracytoplasmic sperm injection pregnancies

Hyperglycosylated human chorionic gonadotropin (H-hCG) is secreted by the placenta in early pregnancy. Decreased H-hCG levels have been associated with abortion in spontaneous pregnancy. We retrospectively measured H-hCG and dimeric hCG in the sera of 87 in vitro fertilization patients obtained in the 3 weeks following embryo transfer and set the results in relation to pregnancy outcome. H-hCG and dimeric hCG were correlated (r(2) = 0.89), and were significantly decreased in biochemical pregnancy (2 microg/l and 18 IU/l, respectively) compared to early pregnancy loss (22 microg/l and 331 IU/l) and ongoing pregnancy (32 microg/l and 353 IU/l). Only H-hCG tended to discriminate between these last two groups.

Anti-Müllerian hormone and inhibin B as predictors of pregnancy after treatment by in vitro fertilization/intracytoplasmic sperm injection

OBJECTIVE: To evaluate anti-Müllerian hormone (AMH) as a marker of reproductive outcome after IVF/intracytoplasmic sperm injection (ICSI). DESIGN: Longitudinal study. SETTING: University hospital. PATIENT(S): Two hundred seventy-six consecutive women undergoing IVF/ICSI. INTERVENTION(S): Ovarian stimulation, oocyte retrieval, IVF, ICSI, embryo transfer, AMH, and inhibin B determinations in serum and follicular fluid (FF). MAIN OUTCOME MEASURE(S): The AMH and inhibin B concentrations in 276 matched FF/serum pairs have been determined. Different outcome groups have been compared and set in relation to the oocyte count, morphological parameters, and steroid hormone levels. RESULT(S): The concentrations of AMH and inhibin B in both serum and FF were significantly higher in the group of women who became pregnant in the corresponding treatment cycle than in those who did not conceive. Positive correlations were observed between serum inhibin B concentrations and embryo morphology (r = 0.126, 95% confidence interval 0.026-0.284). Serum and FF AMH or inhibin B correlated positively with the oocyte count and negatively with the pretreatment cycle day 3 FSH level and the total administered gonadotropin dose. CONCLUSION(S): The AMH and inhibin B levels on the day of oocyte retrieval are correlated to reproductive outcome.

Different anticoagulation strategies in off-pump coronary artery bypass operations: a European survey

In order to determine anticoagulation strategies in OPCAB a questionnaire survey among 750 European cardio-thoracic surgeons was performed. Questions addressed volume of OPCAB procedures performed, intra- and perioperative heparinization and antiplatelet therapy, as well as perioperative management. A total of 325 (43.7%) questionnaires were returned and validated. Perioperative protocols for administration of antiplatelets differed among the respondent surgeons. Perioperative prophylaxis of thrombosis (low or high molecular weight heparin) is performed by 78%. Intraoperative heparin dosage range between 70 U/kg to 500 U/kg, 60% of respondents prefer a low-dose regimen (< or = 150 U/kg). Correspondingly, the lowest activated clotting time (ACT) during surgery is accepted to be 200 s by 24%, 250 s by 18% and 300 s by 26% of surgeons. Protamine is used by 91% of respondents, while 52% perform a 1:1 reversal. A cell-saver and antifibrinolytics are used by 70% and 40%, respectively. Interestingly, 56% of respondents think bleeding in OPCAB patients is not reduced when compared to on-pump CABG. In addition, 34% of respondents believe there is an increased risk of early graft occlusion following OPCAB. This survey demonstrates widely different intra- and perioperative anticoagulation strategies for OPCAB procedures among European surgeons.

Zementaugmentation bei Wirbelmetastasen (Vertebro- und Kyphoplasie) [Cement injection for spinal metastases (vertebroplasty and kyphoplasty)]

Osteolytic lesions of the spine (metastasis, myeloma) can be treated extremely efficiently by percutaneous cement injection. The treatment should be restricted to osteolytic lesions of the vertebral body, and only if a relevant mechanical deterioration is present. If the pedicles and/or the lamina are involved and if there is compression of the spinal canal, the treatment is no longer appropriate. The surgical technique is similar to the treatment of osteoporotic fractures; however, there is definitely a higher risk for cement leakage and the clinical outcome is not as predictable as in osteoporotic fracture treatment. It is important to realize that cement injection per se has no impact on the tumor itself, but provides stability to the vertebral body. An osteolytic lesion without mechanical compromise does not need a vertebroplasty. Patients with tumorous lesions of the spine should be followed by an interdisciplinary team of spine surgeon, oncologist and radio-oncologist.

The effect of pulsed jet lavage in vertebroplasty on injection forces of PMMA bone cement: an animal study

Percutaneous vertebroplasty, comprising of the injection of polymethylmethacrylate (PMMA) into vertebral bodies, is an efficient procedure to stabilize osteoporotic compression fractures as well as other weakening lesions. Besides fat embolism, cement leakage is considered to be one of the major and most severe complications during percutaneous vertebroplasty. The viscosity of the PMMA during injection plays a key role in this context. It was shown in vitro that the best way to lower the risk of cement leakage is to inject the cement at higher viscosity, which is requires high injection forces. Injection forces can be reduced by applying a newly developed lavage technique as it was shown in vitro using human cadaver vertebrae. The purpose of this study was to prove the in vitro results in an in vivo model. The investigation was incorporated in an animal study that was performed to evaluate the cardiovascular reaction on cement augmentation using the lavage technique. Injection forces were measured with instrumentation for 1 cc syringes, additionally acquiring plunger displacement. Averaged injection forces measured, ranged from 12 to 130 N and from 28 to 140 N for the lavage group and the control group, respectively. Normalized injection forces (by viscosity and injection speed) showed a trend to be lower for the lavage group in comparison to the control group (P = 0.073). In conclusion, the clinical relevance on the investigated lavage technique concerning lowering injection forces was only shown by trend in the performed animal study. However, it might well be that the effect is more pronounced for osteoporotic vertebral bodies.