Evaluation of a radiographer-led peripherally inserted central catheter insertion service.

INTRODUCTION: To evaluate a radiographer-led peripherally inserted central catheter (PICC) insertion service within an interventional radiology suite using ultrasound and fluoroscopic guidance. METHODS: Data from 366 consecutive PICC insertions by five trained angiography-specialized radiographers were prospectively collected over a 12-month period. For each PICC insertion, patient demographics, including past medical history of cystic fibrosis (CF), number of punctures, vein used, final tip position, contrast administration and screening time were recorded. Institutional review board approval was obtained. RESULTS: The overall PICC insertion success rate was 100%. Fifty-five (15%) had a known medical history of CF. Three hundred and thirty-one (90%) PICC insertions required a single puncture and 32 (9%) required two punctures. The remaining three insertions required three punctures. The basilic vein was most commonly used (69%) followed by the brachial vein (29%), and the cephalic vein was used only in 2%. Administration of contrast medium was necessary during 27 (7%) PICC insertions. Mean screening time was 10.7 s. CONCLUSION: Our specifically trained, radiographer-led PICC insertion service proved to be successful. Both straightforward and complex insertions, for example in CF patients could be adequately and efficiently performed.

Characterization of Irreversible Electroporation Ablation with a Validated Perfused Organ Model.

PURPOSE: To develop and validate a perfused organ model for characterizing ablations for irreversible electroporation (IRE)-based therapies. MATERIALS AND METHODS: Eight excised porcine livers were mechanically perfused with a modified phosphate-buffered saline solution to maintain viability during IRE ablation. IRE pulses were delivered using 2 monopolar electrodes over a range of parameters, including voltage (1,875-3,000 V), pulse length (70-100 µsec), number of pulses (50-600), electrode exposure (1.0-2.0 cm), and electrode spacing (1.5-2.0 cm). Organs were dissected, and treatment zones were stained with triphenyl tetrazolium chloride to demonstrate viability and highlight the area of ablation. Results were compared with 17 in vivo ablations performed in canine livers and 35 previously published ablations performed in porcine livers. RESULTS: Ablation dimensions in the perfused model correlated well with corresponding in vivo ablations (R2 = 0.9098) with a 95% confidence interval of < 2.2 mm. Additionally, the validated perfused model showed that the IRE ablation zone grew logarithmically with increasing pulse numbers, showing small difference in ablation size over 200-600 pulses (3.2 mm ± 3.8 width and 5.2 mm ± 3.9 height). CONCLUSIONS: The perfused organ model provides an alternative to animal trials for investigation of IRE treatments. It may have an important role in the future development of new devices, algorithms, and techniques for this therapy.

Introduction to Irreversible Electroporation--Principles and Techniques.

Irreversible electroporation (IRE) is a novel nonthermal focal ablation technique that uses a series of brief but intense electric pulses delivered by paired electrodes into a targeted region of tissue, killing the cells by irreversibly disrupting cellular membrane integrity. Unlike other ablation methods, IRE has relatively little effect on connective tissues and nerves and has a low patient effect. The ability of IRE to achieve cell death immediately adjacent to large vessels without effect on the vessels themselves has raised the possibility of better treatment of advanced pancreatic cancer. Because of the low effect on the patient, IRE is well suited for use in conjunction with chemotherapeutic agents. The IRE effect is not uniform and is dependent on the intrinsic conductivity of the tissue, the number of pulses delivered, the current flow achieved, and the total time for the treatment. It is currently under investigation for a wide range of solid tumors and prostate cancer in humans and in animals in the breast, brain, and spinal cord. In clinical practice, IRE can be administered either percutaneously under imaging guidance or at open operation under direct vision. In animals there is some evidence of an immune response presumably due to exposure of the intracellular target material, resulting in a greater therapeutic effect. Unlike many other cancer treatments, IRE has been introduced for human clinical use at a very early stage of development of the technique and much of the basic understanding of how and when to use IRE is still under investigation.

In vivo irreversible electroporation kidney ablation: experimentally correlated numerical models.

Irreversible electroporation (IRE) ablation uses brief electric pulses to kill a volume of tissue without damaging the structures contraindicated for surgical resection or thermal ablation, including blood vessels and ureters. IRE offers a targeted nephron-sparing approach for treating kidney tumors, but the relevant organ-specific electrical properties and cellular susceptibility to IRE electric pulses remain to be characterized. Here, a pulse protocol of 100 electric pulses, each 100 µs long, is delivered at 1 pulse/s to canine kidneys at three different voltage-to-distance ratios while measuring intrapulse current, completed 6 h before humane euthanasia. Numerical models were correlated with lesions and electrical measurements to determine electrical conductivity behavior and lethal electric field threshold. Three methods for modeling tissue response to the pulses were investigated (static, linear dynamic, and asymmetrical sigmoid dynamic), where the asymmetrical sigmoid dynamic conductivity function most accurately and precisely matched lesion dimensions, with a lethal electric field threshold of 575 ± 67 V/cm for the protocols used. The linear dynamic model also attains accurate predictions with a simpler function. These findings can aid renal IRE treatment planning under varying electrode geometries and pulse strengths. Histology showed a wholly necrotic core lesion at the highest electric fields, surrounded by a transitional perimeter of differential tissue viability dependent on renal structure.

An "Off-the-Shelf" System for Intraprocedural Electrical Current Evaluation and Monitoring of Irreversible Electroporation Therapy.

INTRODUCTION: Irreversible electroporation (IRE) ablation uses a series of brief electric pulses to create nanoscale defects in cell membranes, killing the cells. It has shown promise in numerous soft-tissue tumor applications. Larger voltages between electrodes will increase ablation volume, but exceeding electrical limits may risk damage to the patient, cause ineffective therapy delivery, or require generator restart. Monitoring electrical current for these conditions in real-time enables managing these risks. This capacity is not presently available in clinical IRE generators. METHODS: We describe a system using a Tektronix TCP305 AC/DC Current Probe connected to a TCPA300 AC/DC Current Probe Amplifier, which is read on a computer using a Protek DSO-2090 USB computer-interfacing oscilloscope. Accuracy of the system was tested with a resistor circuit and by comparing measured currents with final outputs from the NanoKnife clinical electroporation pulse generator. RESULTS: Accuracy of measured currents was 1.64 ± 2.4 % relative to calculations for the resistor circuit and averaged 0.371 ± 0.977 % deviation from the NanoKnife. During clinical pulse delivery, the system offers real-time evaluation of IRE procedure progress and enables a number of methods for identifying approaching issues from electrical behavior of therapy delivery, facilitating protocol changes before encountering therapy delivery issues. CONCLUSIONS: This system can monitor electrical currents in real-time without altering the electric pulses or modifying the pulse generator. This facilitates delivering electric pulse protocols that remain within the optimal range of electrical currents-sufficient strength for clinically relevant ablation volumes, without the risk of exceeding safe electric currents or causing inadequate ablation.

A randomized, double-blind, placebo-controlled study of preemptive oral oxycodone with morphine patient-controlled anesthesia for postoperative pain management in patients undergoing uterine artery embolization for symptomatic uterine fibroids.

PURPOSE: To evaluate the analgesic efficacy of oral premedication of oxycodone in a group of patients undergoing elective uterine artery embolization under sedation for fibroid disease. METHODS: Thirty-nine patients (mean age 42.3 years) were prospectively randomized 1:1 to receive 20 mg oxycodone or placebo orally immediately before their procedure. At the commencement of the procedure, patients were provided with a patient-controlled analgesia device for 24 h, programmed to deliver 1 mg boluses of intravenous morphine with a 5 min lockout. Mean visual analog scale pain intensity ratings (0-100 mm) were measured from both groups and evaluated over 0 to 6 h as the primary end point. Other measured parameters included opioid-related side effects and eligibility for discharge (NCT00163930; September 12, 2005). RESULTS: Early pain intensity did not vary significantly between the active and placebo groups [mean (standard deviation): 3.2 (2.5) vs. 3.1 (2.2), p = 0.89]. The oxycodone group, however, experienced significantly more nausea (p = 0.035) and a greater incidence of vomiting (p = 0.044). Overall opioid requirement over 24 h, measured as oral morphine equivalent, was greater in the oxycodone group (median [interquartile range]: 64.5 [45-90] mg vs. 22.5 [15-46.5] mg, p < 0.0001). The number of patients first eligible for discharge at 24 h in the oxycodone group was decreased but not significantly (p = 0.07). CONCLUSION: The addition of preprocedural oral oxycodone to morphine patient-controlled analgesia does not offer any analgesic advantage to patients having uterine artery embolization and may cause a greater incidence of nausea and vomiting.

In vivo characterization and numerical simulation of prostate properties for non-thermal irreversible electroporation ablation.

BACKGROUND: Irreversible electroporation (IRE) delivers brief electric pulses to attain non-thermal focal ablation that spares vasculature and other sensitive systems. It is a promising prostate cancer treatment due to sparing of the tissues associated with morbidity risk from conventional therapies. IRE effects depend on electric field strength and tissue properties. These characteristics are organ-dependent, affecting IRE treatment outcomes. This study characterizes the relevant properties to improve treatment planning and outcome predictions for IRE prostate cancer treatment. METHODS: Clinically relevant IRE pulse protocols were delivered to a healthy canine and two human cancerous prostates while measuring electrical parameters to determine tissue characteristics for predictive treatment simulations. Prostates were resected 5 hr, 3 weeks, and 4 weeks post-IRE. Lesions were correlated with numerical simulations to determine an effective prostate lethal IRE electric field threshold. RESULTS: Lesions were produced in all subjects. Tissue electrical conductivity increased from 0.284 to 0.927 S/m due to IRE pulses. Numerical simulations show an average effective prostate electric field threshold of 1072 ± 119 V/cm, significantly higher than previously characterized tissues. Histological findings in the human cases show instances of complete tissue necrosis centrally with variable tissue effects beyond the margin. CONCLUSIONS: Preliminary experimental IRE trials safely ablated healthy canine and cancerous human prostates, as examined in the short- and medium-term. IRE-relevant prostate properties are now experimentally and numerically defined. Importantly, the electric field required to kill healthy prostate tissue is substantially higher than previously characterized tissues. These findings can be applied to optimize IRE prostate cancer treatment protocols.

The effects of metallic implants on electroporation therapies: feasibility of irreversible electroporation for brachytherapy salvage.

PURPOSE: Electroporation-based therapies deliver brief electric pulses into a targeted volume to destabilize cellular membranes. Nonthermal irreversible electroporation (IRE) provides focal ablation with effects dependent on the electric field distribution, which changes in heterogeneous environments. It should be determined if highly conductive metallic implants in targeted regions, such as radiotherapy brachytherapy seeds in prostate tissue, will alter treatment outcomes. Theoretical and experimental models determine the impact of prostate brachytherapy seeds on IRE treatments. MATERIALS AND METHODS: This study delivered IRE pulses in nonanimal, as well as in ex vivo and in vivo tissue, with and in the absence of expired radiotherapy seeds. Electrical current was measured and lesion dimensions were examined macroscopically and with magnetic resonance imaging. Finite-element treatment simulations predicted the effects of brachytherapy seeds in the targeted region on electrical current, electric field, and temperature distributions. RESULTS: There was no significant difference in electrical behavior in tissue containing a grid of expired radiotherapy seeds relative to those without seeds for nonanimal, ex vivo, and in vivo experiments (all p > 0.1). Numerical simulations predict no significant alteration of electric field or thermal effects (all p > 0.1). Histology showed cellular necrosis in the region near the electrodes and seeds within the ablation region; however, there were no seeds beyond the ablation margins. CONCLUSION: This study suggests that electroporation therapies can be implemented in regions containing small metallic implants without significant changes to electrical and thermal effects relative to use in tissue without the implants. This supports the ability to use IRE as a salvage therapy option for brachytherapy.

Investigation of the safety of irreversible electroporation in humans.

PURPOSE: A single-center prospective nonrandomized cohort study was performed to investigate the safety of irreversible electroporation (IRE) for tumor ablation in humans. MATERIALS AND METHODS: Thirty-eight volunteers with advanced malignancy of the liver, kidney, or lung (69 separate tumors) unresponsive to alternative treatment were subjected to IRE under general anesthesia. Clinical examination, biochemistry, and computed tomography (CT) scans of the treated organ were performed before, immediately after, and at 1 month and 3 months after the procedure. RESULTS: No mortalities occurred at 30 days. Transient ventricular arrhythmia occurred in four patients, and electrocardiographically (ECG) synchronized delivery was used subsequently in the remaining 30 patients, with two further arrhythmias (supraventricular tachycardia and atrial fibrillation). One patient developed obstruction of the upper ureter after IRE. One adrenal gland was unintentionally directly electroporated, which produced transient severe hypertension. There was no other evidence of adjacent organ damage related to the electroporation. Other adverse events were not directly related to IRE, but two patients developed temporary neurapraxia as a result of arm extension during a prolonged period of anesthesia. Although not a primary aim of this preliminary study, complete target tumor ablation verified by CT was achieved in 46 of the 69 tumors treated with IRE (66%). Most treatment failures occurred in renal and lung tumors. Biopsy in three patients showed coagulative necrosis in the regions treated by IRE. CONCLUSIONS: IRE appears to be safe for human clinical use provided ECG-synchronized delivery is used. Comparative evaluation with alternative ablative technologies is warranted.

A positive response to a recruitment maneuver with PEEP titration in patients with ARDS, regardless of transient oxygen desaturation during the maneuver.

UNLABELLED: Recruitment maneuvers (RMs) can expand collapsed alveoli in ventilated patients. The optimal method for delivering RMs is unknown. PURPOSE: To evaluate the safety and the respiratory and hemodynamic effects of a staircase recruitment maneuver (SRM) with decremental positive end expiratory pressure (PEEP) titration and the consequences of desaturation during the SRM in patients with early acute lung injury (ALI). METHODS: In total, 20 consecutive patients with early ALI were enrolled and received an SRM. Patients were given 15 ± 3 cm H(2)O pressure-controlled ventilation. Positive end expiratory pressure was increased from baseline (range 10-18) to 20, 30, and 40 cm H(2)O every 2 minutes to achieve maximum alveolar pressure of 55 ± 3 cm H(2)O, then decreased at 3-minute intervals to 25, 22.5, 20, 17.5, and 15 cm H(2)O until a decrease of 1% to 2% oxygen saturation from maximum was detected. Positive end expiratory pressure was left at the level where the fall in oxygen saturation occurred. Standard respiratory and circulatory variables, arterial and central venous gases were measured before, during, and after the SRM. RESULTS: There were significant improvements in shunt fraction (36.3% ± 10% to 26.4% ± 14%, P < .001), oxygen saturation (93.4% ± 2% to 96.8% ± 3%, P = .007), partial pressure of oxygen, arterial (PaO(2))/fraction of inspired oxygen ([FIO(2)]; 150 ± 42 to 227 ± 100, P = .004), lung compliance (33.9 ± 9.1 to 40.1 ± 11.4 mL/cm H(2)O, P < .01), and chest x-ray (CXR) after the SRM. Briefly, 80% of the patients responded and the response was maintained at 1 hour. In total, 8 patients desaturated 6.1% ± 2.8% in SaO(2) during the SRM but 5 of those improved SaO(2) relative to baseline by the end of the SRM. CONCLUSIONS: In all, 80% of the patients with early ALI responded to the SRM with decremental PEEP titration. Desaturation during the SRM did not indicate a failed response 1 hour later.

Catheter-directed thrombolysis of lower limb thrombosis.

Late complications of thrombosis of the deep veins in the region between the popliteal vein termination and the confluence of the common iliac veins and inferior vena cava (suprapopliteal deep-vein thrombosis) are common and often unrecognized by those responsible for the initial management. Pharmacomechanical-assisted clearance of the thrombus at the time of first presentation provides the best opportunity for complete recovery with preservation of normal venous valve function and avoidance of recurrent deep-vein thrombosis and postthrombotic syndrome. Recent interventional radiology methods provide for rapid and complete thrombolysis even in some patients in whom thrombolysis was previously considered contraindicated. This review describes the methods, safety, and efficacy of acute interventional treatment of suprapopliteal deep-vein thrombosis.

Irreversible electroporation: a new challenge in "out of operating theater" anesthesia.

BACKGROUND: Bioelectrics, an interesting new area of medicine, combines pulsed high-voltage engineering with cell biology and has many potential applications. Pulsed electric current can be used to produce irreversible electroporation (IRE) of cell membranes with resulting cell death. This process has been shown to ablate tumors in animal studies. METHODS: A clinical trial of IRE as a tumor ablation therapy was performed at our institution. A pulsating direct current of 20 to 50 A and 500 to 3000 V was delivered into metastatic or primary tumors in the liver, kidney, or lung via needle electrodes inserted under computed tomography (CT) or ultrasound guidance. Patients required a relaxant general anesthetic. We describe some challenges presented to anesthesiologists. Guidelines for anesthesia were produced and modified as issues became apparent. The patients' charts were audited throughout. RESULTS: We noted a number of issues. The electrical discharge produced generalized upper body muscular contractions requiring neuromuscular blockade. Two patients developed positional neuropraxia because of the extended arm position requested for CT scanning. After experimentation, we have developed a modified arm position. Some patients developed self-limiting ventricular tachycardias that are now minimized by using an electrocardiogram synchronizer. Three patients developed pneumothoraces as a result of the needle electrode insertion. CONCLUSIONS: Relaxant general anesthesia is required for IRE of the liver, lung, and kidney. An electrocardiogram synchronizer should be used to minimize the risk of arrhythmias. Attention to the position of the arms is required to maximize CT scan quality but minimize brachial plexus strain. Simple postoperative analgesia is all that is required in most patients.

Rendezvous technique following thermal ureteric injury after radiofrequency ablation in a solitary kidney.

Percutaneous radiofrequency (RF) ablation is a promising treatment for solid renal tumors in selected patients. Nontarget thermal damage is a known risk of the procedure. The authors describe a case of a patient who underwent RF ablation of a lower pole renal lesion and subsequently developed a ureteric stricture secondary to thermal injury. Successful management of the ureteric stricture required a rendezvous procedure. This report illustrates the potential complication of ureteric stricture formation after a RF ablation procedure and the management challenges posed by such thermal injuries.

T2 dark blood MRA for renal artery stenosis detection: preliminary observations.

OBJECTIVE: This study evaluated the ability of a fast spin echo T2 weighted dark blood sequence to characterize significant (>50%) renal artery stenosis compared to conventional angiography. METHODS: Sixteen patients underwent conventional catheter angiography for either renal artery stenosis evaluation or as potential renal donors. Each patient then had an MR study of the renal arteries and kidneys with fast spin echo T2 weighted MR (TR 4000, TE 102, 8 echo train length) on a Superconducting 1.5T Magnet. Results were compared with angiography and inter and intra observer statistics were calculated. RESULTS: A total of 36 renal arteries were imaged in 32 kidneys with 12 stenoses >50%. Fast spin echo T2 weighted MR is 94% accurate (95%CI: 87-100%) in detection of significant renal artery stenosis. Dark blood MRA (DBMRA) is 96% sensitive (95%CI: 89-100), 92% specific, with a predictive value positive of 96% for classifying real arteries as normal or significantly stenosed. Inter and intra observer statistics demonstrate good to excellent agreement in renal artery classification (kappa>0.60). CONCLUSION: DBMRA may be a useful adjunct to renal MR evaluation in hypertension. SUMMARY: A total of 36 renal arteries were imaged in 32 kidneys with 12 stenoses >50%. Fast spin echo T2 weighted MR is 94% accurate (95%CI: 87-100%) in detection of significant renal artery stenosis.