Comparison of a suspended radiation protection system versus standard lead apron for radiation exposure of a simulated interventionalist.

PURPOSE: To evaluate the radiation protective characteristics of a system designed to enhance operator protection while eliminating weight to the body and allowing freedom of motion. MATERIALS AND METHODS: Radiation doses to a mock interventionalist were measured with calibrated dosimeters in a clinical interventional suite. A standard lead apron (SLA; Pb equivalent, 0.5 mm) was compared with a suspended radiation protection system (ZeroGravity; Zgrav) that shields from the top of the head to the calves (except the right arm and left forearm) with a complex overhead motion system that eliminates weight on the operator and allows freedom of motion. Zgrav included a suspended lead apron with increased lead equivalency, greater length, proximal left arm and shoulder coverage, and a wraparound face shield of 0.5 mm Pb equivalency. A 26-cm-thick Lucite stack (ie, mock patient) created scatter during 10 controlled angiography sequences of 120 exposures each. Parameters included a field of view of 40 cm, table height of 94 cm, 124 cm from the tube to image intensifier, 50 cm from the image center to operator, 66 kVp, and 466-470 mA. RESULTS: Under identical conditions, average doses (SLA vs Zgrav) were 264 versus 3.4 (ratio, 78) to left axilla (P < .001), 456 versus 10.2 (ratio, 45) to left eye (P < .001), 379.4 versus 6.6 (ratio, 57) to right eye (P < .005), and 18.8 versus 1.2 (ratio, 16) to gonad (P < .001). CONCLUSIONS: Relative to a conventional lead apron, the Zgrav system provided a 16-78-fold decrease in radiation exposure for a mock interventionalist in a simulated clinical setting.

Left colic artery pseudoaneurysm from pancreatitis presenting as upper gastrointestinal hemorrhage.

Visceral pseudoaneurysms resulting from pancreatitis occur in approximately 10% of cases. The present report describes a left colic artery pseudoaneurysm from pancreatitis presenting with active duodenal bleeding. Based on the clinical and endoscopic demonstration of duodenal bleeding, celiac and superior mesenteric arteriograms were initially obtained, and their findings were negative. Repeat arteriography, including an inferior mesenteric artery injection, demonstrated a left colic pseudoaneurysm with rupture into the pancreatic duct and retrograde flow into the duodenum. Because of inconsistent diagnostic yields for arteriography performed for pancreatitis-related bleeding, the authors recommend disciplined interrogation of all three major mesenteric vessels, unbiased by initial endoscopic findings, to reduce false-negative examination results and empiric embolization.

Mediastinal transthoracic needle and core lymph node biopsy: should it replace mediastinoscopy?

STUDY OBJECTIVES: Primary assessment of mediastinal lymph nodes (N2 or N3) for staging lung cancer by transthoracic needle with or without core biopsy. Mediastinoscopy only performed after FNA failed to yield a diagnosis. DESIGN AND SETTINGS: A retrospective study in a university setting. PATIENTS: Eighty-nine patients with mediastinal lymphadenopathy (> 1.5 cm in short-axis diameter) by CT. METHODS: Mediastinal transthoracic fine-needle aspiration (FNA) with or without core biopsy was performed prior to mediastinoscopy in 89 patients with mediastinal lymphadenopathy (lymph node > 1.5 cm in short-axis diameter) or masses by CT. RESULTS: Mediastinal transthoracic FNA was used alone in 39 of 89 patients, or with core biopsy in 50 of 89 patients. Mediastinal transthoracic FNA with or without core biopsy was diagnostic in 69 of 89 patients (77.5%) for cancer cell type, sarcoidosis, or caseating granulomas with or without tuberculosis. Transthoracic FNA with or without core biopsy of nodal stations (total, 94 biopsies) judged readily accessible by mediastinoscopy (n = 59) included paratracheal (n = 56) and highest mediastinal (n = 3); those more difficult (n = 26) included subcarinal (n = 20) and aorticopulmonary window (n = 6); and those impossible (n = 9) included paraesophageal and pulmonary ligament (n = 6), parasternal (n = 2), and para-aortic (n = 1). Innovative lung protective techniques for CT-guided biopsy access windows included "iatrogenic-controlled pneumothorax" (n = 10) or saline solution injection creating a "salinoma" (n = 11). Pneumothorax was detected in only 10% with a "protective" technique but 60% when traversing lung parenchyma. Transthoracic FNA with or without core biopsy failed to yield a diagnosis in 20 of 89 patients (22.5%); all then underwent mediastinoscopy, with 11 of 20 procedures (55%) diagnostic for cancer, and 9 of 20 procedures diagnostic of benign diagnosis or no cancer. CONCLUSION: Transthoracic FNA with or without core biopsy accesses virtually all mediastinal nodal stations is diagnostic in 78% of cases with mediastinal adenopathy or masses, and should precede mediastinoscopy in the staging of lung cancer or workup of mediastinal masses.

Salinoma window technique for mediastinal lymph node biopsy.

Computed tomographic-guided transthoracic needle biopsy can access virtually all mediastinal lymph node stations, but is limited by the potential for pneumothorax and bleeding. To avoid these possible complications, the extrapleural "salinoma" technique was used for computed tomographic-guided mediastinal biopsies in 15 patients. Sampling methods were coaxial (8), tandem (5), and single pass (2). Diagnostic yield was 93% with no significant bleeding or pneumothorax. The salinoma technique permits biopsy of deep mediastinal lesions to stage pulmonary malignancies, while providing a technique that limits complications.

The effect of the Varian amorphous silicon electronic portal imaging device on exit skin dose.

Measurements have been made of the increase in exit surface dose resulting from backscattered radiation generated by the Varian amorphous silicon electronic portal imaging device (EPID). An increase of < or = 14% was demonstrated at both 6 MV and 10 MV, in a manner which suggests that backscatter from the EPID acts to re-establish electronic equilibrium at the exit surface, normally absent in the build-down region. The magnitude of this effect was influenced by field size, measurement depth and exit surface to EPID distance. Assuming typical constraints of portal imaging frequency and geometry, the results suggest that EPID generated backscatter is unlikely to alter the frequency or severity of exit skin reactions. However, the results do suggest that a limit on the minimum separation between the EPID and the exit surface should be set, and that similar investigations should be made for other EPID models.

Arterio-venous CO2 removal (AVCO2R) perioperative management: rapid recovery and enhanced survival.

Percutaneous arteriovenous CO2 removal (AVCO2R) uses a simple arteriovenous (A-V) shunt for near-total CO2 removal that allows significant reductions in minute ventilation. We critically reviewed our algorithm-directed perioperative anesthesia management in our LD40 ovine smoke-burn injury model of acute respiratory distress syndrome (ARDS) treated with AVCO2R. General anesthesia is required for: (1) Vascular access followed by ARDS model development by smoke insufflation (36 breaths) plus 40% TBSA III degrees burn with mechanical ventilation. Induction: 12.5 mg/kg im ketamine and 4% halothane by mask, then intubation. Maintenance: 1.0-2.5% halothane in 100% O2; (2) When PaO2/FiO2 < 200 (48-52 h), sheep randomized to the AVCO2R (n = 8) or SHAM (n = 8) procedure. Induction: 66% N2O and 5% isoflurane in balance O2. Maintenance: 1.5-2.5% isoflurane in 100% O2 for AVCO2R, cannulation (10F carotid artery, 14F jugular vein); (3) Postop, both groups had algorithm-directed ventilator management, identical heparin (ACT > 300 s), fluid, and analgesia management. All sheep met criteria for ARDS, survived anesthesia, and were standing by 0.5-5 h. There were no complications attributable to anesthesia. The absence of anesthesia-related complications allows model development for outcomes studies for ARDS in general and AVCO2R specifically.

Toward ambulatory arteriovenous CO2 removal: initial studies and prototype development.

Extracorporeal arteriovenous carbon dioxide removal (AVCO2R) using percutaneous cannulae and a low resistance gas exchanger achieves near total CO2 removal, allowing lung rest and potentially improving survival. AVCO2R, redesigned to allow ambulation, has potential as treatment for severe chronic obstructive pulmonary disease or rehabilitation before lung transplant. The purposes of this study were to 1) determine the optimal ambulatory access for AVCO2 removal and 2) develop a prototype Ambulatory-AVCO2R gas exchanger. Initially, reinforced Gore-Tex 6 mm (two) and 8 mm (four) grafts were anastomosed to sheep carotid arteries and jugular veins as a loop in parallel to the cranial circulation to determine blood flow capabilities. Blood flow was 100-150 ml/min with a 14 gauge dialysis needle, and transected 6 mm Gore-Tex grafts achieved 500-900 ml blood flow, whereas transected 8 mm grafts achieved up to 2000 ml/min flow. The polytetrafluoroethylene (PTFE) loops were then connected to our newly developed ultra low resistance pumpless gas exchanger for ambulatory AVCO2R. The average pressure gradient across the prototype Ambulatory-AVCO2R gas exchangers (n = 5) was 2.8 +/- 0.8 mm Hg, and mean CO2 removal was 104.8 +/- 14.0 ml/min, with an average blood flow of 900 ml/min. We conclude that an 8 mm Gore-Tex reinforced graft arteriovenous loop supplies ample blood flow for our new ultra low resistance Ambulatory-AVCO2R to achieve near total CO2 removal.

Short term performance evaluation of a perfluorocopolymer coated gas exchanger for arteriovenous CO2 removal.

A new perfluorocopolymer coating for micropore hollow fiber gas exchangers was developed to improve gas exchange, reduce plasma leakage, and reduce blood-surface interactions. The present authors evaluated gas exchanger performance using this new coating in a prospective, randomized, controlled, unblinded, large animal model of CO2 retention. Adult sheep (30-40 kg), under general anesthesia, underwent cannulation of the carotid artery (12 F) and jugular vein (14 F). The perfluorocopolymer coated (n = 5) and uncoated (n = 5) gas exchangers were attached to an arteriovenous CO2 removal (AVCO2R) circuit. Blood gases, CO2 removal, and hemodynamics were monitored throughout the 6 hour study. Average CO2 removal was 107.6 +/- 15.6 ml/min (coated) vs. 93.0 +/- 13.9 ml/min (uncoated; p < 0.01). PaCO2 and CO2 removal for both coated and uncoated did not deteriorate significantly over the study. Average AVCO2R blood flow was 1,130 +/- 25 ml/min (coated) versus 1,101 +/- 79 ml/min (uncoated; p = not significant). Likewise, cardiac output and AVCO2R blood flow did not change over the duration of the study. No significant differences in the pressure gradient or resistance between devices (coated, 6.89 +/- 1.14 mm Hg/L/min; uncoated, 6.42 +/- 0.23 mm Hg/L/min) was noted. The authors concluded that the new perfluorocopolymer coated gas exchanger improved CO2 removal without compromising hemodynamics in an acute performance evaluation.

Malignant eccrine acrospiroma with metastasis to the parotid.

Malignant eccrine acrospiromas are rare. Clinically, they resemble other cutaneous lesions. A high index of suspicion must be maintained in cases of histologically benign eccrine acrospiromas for three reasons: (1) malignant transformation can occur, (2) the presence of both benign and malignant tissue can lead to a false-negative diagnosis if only the benign component is obtained in the biopsy specimen, and (3) benign-appearing tumors can recur locally or metastasize. The primary treatment is wide local excision with or without lymph node dissection. The efficacy of adjuvant chemotherapy and radiation therapy requires further investigation. We describe a case of malignant eccrine acrospiroma in an 80-year-old man, and we review the literature on this tumor, with emphasis on the differential diagnosis.

Comparison of fluoroscopic operator eye exposures when working from femoral region, side, or head of patient.

Operator radiation exposure is an important occupational hazard compounded over the course of an interventional radiologist's career. This study compared operator radiation dose to the eye and head for different positions around the patient. Compared with cases performed from the femoral region, exposures were 1.8 times higher at the side, and 1.6 times higher at the head, using conventional aprons, table shields, and mobile suspended shields. Exposures were 99% lower when using a suspended personal radiation protection system in all positions. In conclusion, standing at the side or head results in higher head exposures in a conventional setup.

Endovascular caudal retraction of the cranial end of a misplaced Viatorr TIPS prior to liver transplantation.

Transjugular intrahepatic portosystemic shunt (TIPS) extension far into the inferior vena cava (IVC) or the right atrium may complicate or preclude orthotopic liver transplantation depending on the space available for placement of a hemostatic clamp in the suprahepatic IVC. Until 2004, most TIPS were performed with bare metal stents, which integrate into the vessel wall, making percutaneous or intraoperative repositioning uncertain. Most TIPS are currently created with stent grafts that have an outer fabric to increase shunt patency and prevent endothelial ingrowth. We describe the first known manipulation of a covered stent graft prior to transplantation. The stent graft, which extended well into the IVC, was snared from a femoral approach and deflected caudally in order to document feasibility and nonadherence to the vein wall prior to definitive surgical planning of liver transplantation. Provisions were made for endovascular retraction during actual transplant surgery 9 weeks later, but this became unnecessary when manual retraction of the exposed liver enabled suprahepatic IVC clamping. Due to the nonadherent nature of the outer graft material, compared with a bare metal stent, extension of a stent graft into the IVC or right atrium may not preclude transplantation, and intraoperative endovascular retraction may be considered.

Benign endobronchial granular cell tumor resulting in right middle lobe collapse.

Granular cell tumors (GCTs) are generally benign neoplastic tumors of neural origin that have little malignant potential. These tumors may occur in any location, including the tracheobronchial tree. Although an endobronchial location is believed to represent a small percentage of cases, GCTs should be included in the differential considerations of any endobronchial lesions leading to airway collapse.

Determination of minimum effective height of transparent radiation face shielding for fluoroscopy.

During interventional procedures, the vast majority of scatter radiation originates from the patient and table and travels in all directions in straight lines. Because the operator's head is much higher than the patient and at an angle upward and to the side of the patient (not directly above), the scatter received by the operator's head is projected in an upward angle. Thus a face shield could potentially be lower than the object it is shielding, e.g., below the eyes. This principle may be used as an advantage to design the lowest shield that effectively protects the head while providing optimum vision, appearance, acoustics, low weight, and sense of openness. A flat acrylic plate shield, 0.5 mm Pb equivalence, was suspended vertically in front of a 451P dosimeter. A phantom patient created scatter in an interventional suite while the dosimeter was placed at the level of the crowns of different operators' heads. Many different configurations were tested to determine which ones would provide effective shielding. The results confirmed that the top of the shield may reside several centimeters below the vertical height of the dosimeter (operator's crown), allowing line of sight to monitor above the shield, and still provide effective shielding equivalent to when the dosimeter is positioned directly behind the center of the shield. The image receptor functioned as an effective shield against scatter. Factors increasing the minimum height of effective shielding included shorter operator, opposite oblique projection of image receptor, and shield closer to the face (in horizontal direction).

Transjugular intrahepatic portosystemic shunt creation for recurrent gastrointestinal bleeding during pregnancy.

Treatment of bleeding esophageal varices during pregnancy is a rare clinical dilemma. Primary therapy remains endoscopy and band ligation. Refractory variceal hemorrhage treated with a transjugular intrahepatic portosystemic shunt (TIPS) procedure potentially exposes the fetus to radiation. The present report describes a TIPS procedure performed at 22 weeks gestation with the use of radiation-sparing maneuvers in a patient with recurrent esophageal variceal hemorrhage. The TIPS procedure delivered an estimated fetal dose of 5.49 mSv (0.549 Rad), much less than the dose threshold thought to induce biologic effects and only slightly greater than annual background radiation. The interventional radiologist should not hesitate to perform a TIPS procedure for refractory variceal hemorrhage with use of strategies aimed at minimizing radiation.

High-frequency percussive ventilation with systemic heparin improves short-term survival in a LD100 sheep model of acute respiratory distress syndrome.

We undertook an assessment of high-frequency percussive ventilation (HFPV) and systemic heparin on survival in our LD100 sheep model of smoke/burn-induced acute respiratory distress syndrome (ARDS). This was a prospective controlled outcomes study in a large animal critical care laboratory. ARDS was induced in 13 sheep by a combination of 48 cotton smoke breaths and 40% full-thickness cutaneous burn (LD100) followed by mechanical ventilation (15 ml/kg tidal volume). After meeting ARDS criteria (PaO2/FiO2 < 200), the sheep were divided into high-frequency percussive ventilation (HFPV; n = 7) or volume-controlled mechanical ventilation (VCMV; n = 6) groups. Both groups received systemic heparin to achieve an ACT 180-300 seconds. HFPV was managed with the Volumetric Diffusive Respiration Ventilator (Percussionaire Corp., Sandpoint, ID). The VCMV group was managed with up to 10 ml/kg tidal volume. Arterial blood gases and ventilator settings were monitored every 6 hours after onset of ARDS. HFPV did not affect sheep hemodynamics. Survival 84 hours after smoke and burn injury was significantly greater in the HFPV (7/7, 100%) compared with the VCMV group (3/6, 50%, P < .05). PaCO2 was significantly greater in VCMV group at 36, 48, and 72 hours after smoke and burn injury. PaO2/FiO2 after 36 hours of smoke and burn injury in the HFPV group was improved compared with the VCMV group, but no statistical difference was found. In the VCMV group, peak airway pressure was decreased to 19.7 +/- 2.2 cm H2O at 36 hours from 29 +/- 2.8 at 24 hours as the tidal volume changed from 15 ml/kg to 10 ml/kg and then gradually increased to 39 +/- 5.6 cm H2O at 72 hours. In the HFPV group, peak inspiratory pressure kept constant at a level of 30 cmH2O. In our smoke/burn-induced LD100 sheep model of ARDS, volume-controlled mechanical ventilation with systemic heparin achieved a 50% survival whereas HFPV with systemic heparin achieved 100% survival at 60 hours after the onset of ARDS.

Thoracic imaging in the ICU. Interventional radiology.

Radiology in the intensive care unit (ICU) patient is dominated by plain x-rays, with noteworthy findings prompting further imaging and possible intervention. This chapter discusses interventional and minimally invasive techniques used to treat pleural, mediastinal and pulmonary parenchymal problems commonly encountered in the ICU.

Postthoracotomy pain management.

The following techniques appear efficacious in controlling postthoracotomy pain and reducing the amount of systemic opioids consumed: continuous intercostal blockade, paravertebral blockade, and epidural opioids and/or anesthetics. The combination of thoracic epidural opioid and local anesthetic is very effective at relieving postthoracotomy pain, however, considerable experience is required for insertion of the thoracic epidural catheter and postoperative respiratory monitoring. Intercostal and paravertebral catheters can be inserted intraoperatively under direct visualization, to reduce complications of insertion. One-time intraoperative intercostal blockade may effectively reduce postoperative pain in the first day, but is not a practical long-term method for postthoracotomy pain. The effectiveness of interpleural analgesia, even with proper technique, appears inferior to epidural and other regional techniques. We have incorporated the principles outlined in this review into our general thoracic surgery protocol, as detailed in Fig. 1. Every patient is assessed preoperatively for epidural catheter placement. Contraindications include low platelet count (< 100,000), abnormal coagulation profile, medicinal anticoagulation (aspirin and nonsteroidal anti-inflammatories are not contraindications), bony spinal abnormalities, or neurological disorders. The T5/6 interspace is our preferred level, but T10 can work well with an increased dose of bupivacaine. Upon completion of the muscle sparing, minimal-access thoracotomy, we close the wound and perform a percutaneous intercostal nerve block (two ribs above and three below the incision). We then use patient-controlled epidural analgesia, with a basal infusion of bupivacaine and hydromorphone. To supplement inadequate or nonfunctioning epidurals, intravenous patient-controlled opioids are added. When choosing an approach to postthoracotomy pain management, the thoracic surgeon and anesthesiologist must consider the following: (1) the physician's experience, familiarity and personal complication rate with specific techniques; (2) the desired extent of local and systemic pain control; (3) the presence of contraindications to specific analgesic techniques and medications; and (4) availability of appropriate facilities for patient assessment and monitoring postthoracotomy. Refinements in surgical technique including limited or muscle-sparing thoracotomy, video-assisted thoracoscopic surgery (VATS) and robotic surgery may lessen the magnitude of postthoracotomy pain. We encourage all thoracic surgeons to be knowledgeable of available techniques and maintain a protocol to generate a database for periodic assessment of safety and efficacy.

Percutaneous retrieval of chronic intravascular foreign bodies.

To evaluate the feasibility of intravascular retrieval of chronic foreign bodies, we retrospectively reviewed an 8 year experience (1993-2001) of percutaneous retrieval of chronically retained intravascular foreign bodies (n = 6). In 6 of 6 cases (4 catheter fragments, 2 guidewires), 5-90 days elapsed before retrieval via the femoral or internal jugular vein. Under fluoroscopy, we determined the foreign body's course, position and size. A guidewire was advanced through a multipurpose catheter to the foreign body. The multipurpose catheter was replaced with a gooseneck snare catheter and the snare advanced to grasp and remove the foreign body. Percutaneous retrieval was successful in all 6 cases. One patient experienced mild hemoptysis, which resolved within 24 hr of observation. No patient experienced long-term sequelae. Given the potential life-threatening complications from intravascular foreign bodies and the low complication rate from percutaneous retrieval, we recommend extraction of the foreign body even if it is asymptomatic in the chronic setting (> 24 hr).