Emergency reflex action drill for traumatic cardiac arrest in a simulated pre-hospital setting; a one-group pre-post intervention study.

BACKGROUND: Emergency Reflex Action Drills (ERADs) are meant to decrease stress-associated cognitive demand in high urgency situations. The aim of this study was to develop and test an ERAD for witnessed traumatic cardiac arrest (TCA), an event in which potentially reversible causes need to be systematically addressed and treated in a short period of time. We hypothesize that this ERAD (the TCA-Drill) helps ground Emergency Medical Services (EMS) nurses in overcoming performance decline during this specific high-pressure situation. METHODS: This was a prospective, experimental one-group pre-post intervention study. Ground EMS nurses participated in a session of four simulated scenarios, with an in-between educational session to teach the TCA-Drill. Scenarios were video recorded, after which adherence and time differences were analyzed. Self-confidence on clinical practice was measured before and after the scenarios. RESULTS: Twelve ground EMS nurses participated in this study. Overall median time to address reversible causes of TCA decreased significantly using the TCA-Drill (132 vs. 110 s; p = 0.030) compared with the conventional ALS strategy. More specifically, participants adhering to the TCA-Drill showed a significantly lower time needed for hemorrhage control (58 vs. 37 s; p = 0.012). Eight of 12 (67 %) ground EMS nurses performed the ERAD without protocol deviations. Reported self-confidence significantly increased on 11 of the 13 surveyed items. CONCLUSIONS: The use of an ERAD for TCA (the TCA-Drill) significantly reduces the time to address reversible causes for TCA without delaying chest compressions in a simulated environment and can be easily taught to ground EMS nurses and increases self-confidence. IMPLICATIONS FOR CLINICAL PRACTICE: The use of an ERAD for TCA (the TCA-Drill can significantly reduce the time to address reversible causes for TCA without delaying chest compression. This drill can be easily taught to ground EMS nurses and increases their self-confidence in addressing TCA-patients.

A novel method to perform morphological measurements on three-dimensional (3D) models of the calcaneus based on computed tomography (CT)-imaging.

Background: While current preoperative and postoperative assessment of the fractured and surgically reconstructed calcaneus relies on computed tomography (CT)-imaging, there are no established methods to quantify calcaneus morphology on CT-images. This study aims to develop a semi-automated method for morphological measurements of the calcaneus on three-dimensional (3D) models derived from CT-imaging. Methods: Using CT data, 3D models were created from healthy, fractured, and surgically reconstructed calcanei. Böhler's angle (BA) and Critical angle of Gissane (CAG) were measured on conventional lateral radiographs and corresponding 3D CT reconstructions using a novel point-based method with semi-automatic landmark placement by three observers. Intraobserver and interobserver reliability scores were calculated using intra-class correlation coefficient (ICC). In addition, consensus among observers was calculated for a maximal allowable discrepancy of 5 and 10 degrees for both methods. Results: Imaging data from 119 feet were obtained (40 healthy, 39 fractured, 40 reconstructed). Semi-automated measurements on 3D models of BA and CAG showed excellent reliability (ICC: 0.87-1.00). The manual measurements on conventional radiographs had a poor-to-excellent reliability (ICC: 0.22-0.96). In addition, the percentage of consensus among observers was much higher for the 3D method when compared to conventional two-dimensional (2D) measurements. Conclusions: The proposed method enables reliable and reproducible quantification of calcaneus morphology in 3D models of healthy, fractured and reconstructed calcanei.

Talus-derived reference coordinate system for 3D calcaneal assessment: A novel approach to improve morphological measurements.

In 3D-analysis of the calcaneus, a consistent coordinate system aligned with the original anatomical directions is crucial for pre- and postoperative analysis. This importance stems from the calcaneus's key role in weight-bearing and biomechanical alignment. However, defining a reliable coordinate system based solely on fractured or surgically reconstructed calcanei presents significant challenges. Given its anatomical prominence and consistent orientation, the talus offers a potential solution to this challenge. Our work explores the feasibility of talus-derived coordinate systems for 3D-modeling of the calcaneus across its various conditions. Four methods were tested on nonfractured, fractured and surgically reconstructed calcanei, utilizing Principal Component Analysis, anatomical landmarks, bounding box, and an atlas-based approach. The methods were compared with a self-defined calcaneus reference coordinate system. Additionally, the impact of deviation of the coordinate system on morphological measurements was investigated. Among methods for constructing nonfractured calcanei coordinate systems, the atlas-based method displayed the lowest Root Mean Square value in comparison with the reference coordinate system. For morphological measures like Böhler's Angle and the Critical angle of Gissane, the atlas talus-based system closely aligned with ground truth, yielding differences of 0.6° and 1.2°, respectively, compared to larger deviations seen in other talus-based coordinate systems. In conclusion, all tested methods were feasible for creating a talus derived coordinate system. A talus derived coordinate system showed potential, offering benefits for morphological measurements and clinical scenarios involving fractured and surgically reconstructed calcanei. Further research is recommended to assess the impact of these coordinate systems on surgical planning and outcomes.

Opportunities and barriers for prehospital emergency medical services research in the Netherlands; results of a mixed-methods consensus study.

INTRODUCTION: Quality improvement in prehospital emergency medical services (EMS) can only be achieved by high-quality research and critical appraisal of current practices. This study examines current opportunities and barriers in EMS research in the Netherlands. METHODS: This mixed-methods consensus study consisted of three phases. The first phase consisted of semi-structured interviews with relevant stakeholders. Thematic analysis of qualitative data derived from these interviews was used to identify main themes, which were subsequently discussed in several online focus groups in the second phase. Output from these discussions was used to shape statements for an online Delphi consensus study among relevant stakeholders in EMS research. Consensus was met if 80% of respondents agreed or disagreed on a particular statement. RESULTS: Forty-nine stakeholders participated in the study; qualitative thematic analysis of the interviews and focus group discussions identified four main themes: (1) data registration and data sharing, (2) laws and regulations, (3) financial aspects and funding, and (4) organization and culture. Qualitative data from the first two phases of the study were used to construct 33 statements for an online Delphi study. Consensus was reached on 21 (64%) statements. Eleven (52%) of these statements pertained to the storage and use of EMS patient data. CONCLUSION: Barriers for prehospital EMS research in the Netherlands include issues regarding the use of patient data, privacy and legislation, funding and research culture in EMS organizations. Opportunities to increase scientific productivity in EMS research include the development of a national strategy for EMS data and the incorporation of EMS topics in research agendas of national medical professional associations.

Non-compressible truncal and junctional hemorrhage: A retrospective analysis quantifying potential indications for advanced bleeding control in Dutch trauma centers.

BACKGROUND: Truncal and junctional hemorrhage is the leading cause of potentially preventable deaths in trauma patients. To reduce this mortality, the application of advanced bleeding control techniques, such as resuscitative endovascular balloon occlusion of the aorta (REBOA), junctional tourniquets, Foley catheters, or hemostatic agents should be optimized. This study aimed to identify trauma patients with non-compressible truncal and junctional hemorrhage (NCTJH) who might benefit from advanced bleeding control techniques during initial trauma care. We hypothesized that there is a substantial cohort of Dutch trauma patients that can possibly benefit from advanced bleeding control techniques. METHODS: Adult trauma patients with an Abbreviated Injury Scale ≥3 in the torso, neck, axilla, or groin region, who were presented between January 1st, 2014 and December 31st, 2018 to two Dutch level-1 trauma centers, were identified from the Dutch Trauma Registry. Potential indications for advanced bleeding control in patients with NCTJH were assessed by an expert panel of three trauma surgeons based on injury characteristics, vital signs, response to resuscitation, and received treatment. RESULTS: In total, 1719 patients were identified of whom 249 (14.5 %) suffered from NCTJH. In 153 patients (60.6 %), hemorrhagic shock could have been mitigated or prevented with advanced bleeding control techniques. This group was younger and more heavily injured: median age of 40 versus 48 years and median ISS 33 versus 22 as compared to the entire cohort. The mortality rate in these patients was 31.8 %. On average, each of the included level-1 trauma centers treated an NCTJH patient every 24 days in whom a form of advanced bleeding control could have been beneficial. CONCLUSIONS: More than half of included Dutch trauma patients with NCTJH may benefit from in-hospital application of advanced bleeding control techniques, such as REBOA, during initial trauma care. Widespread implementation of these techniques in the Dutch trauma system may contribute to reduction of mortality and morbidity from non-compressible truncal and junctional hemorrhage.

Impact of Point-of-Care Ultrasound on Prehospital Decision Making by HEMS Physicians in Critically Ill and Injured Patients: A Prospective Cohort Study.

INTRODUCTION: Several studies have shown the additional benefit of point-of-care ultrasound (POCUS) by prehospital Emergency Medical Services (EMS). Since organization of EMS may vary significantly across countries, the value of POCUS likely depends on the prehospital system in which it is used. In order to be able to optimally implement POCUS and develop a tailored training curriculum, it is important to know how often POCUS is currently used, for which indications it is used, and how it affects decision making. The aims of this study were: (1) to determine the percentage of patients in whom POCUS was used by Dutch Helicopter Emergency Medical Services (HEMS) crews; (2) to determine how often POCUS findings led to changes in on-scene management; and (3) what these changes were. METHODS: Patients who received prehospital care from December 1, 2020 through March 31, 2021 by a single HEMS crew were included in this prospective cohort study. Clinical data and specific data on POCUS examination, findings, and therapeutic consequences were collected and analyzed. RESULTS: During the study period, on-scene HEMS care was provided to 612 patients, of which 211 (34.5%) patients underwent POCUS. Of these, 209 (34.2%) patients with a median age of 45 years were included. There were 131 (62.7%) trauma patients, and 70 (33.7%) of the included patients underwent cardiopulmonary resuscitation (CPR). The median reported time of POCUS examination was three (P25-P75 2-5) minutes. Median prolongation of on-scene time was zero (P25-P75 0-1) minutes. In 85 (40.7%) patients, POCUS examination had therapeutic consequence: POCUS was found to impact treatment decisions in 34 (26.0%) trauma patients and 51 (65.4%) non-trauma patients. In patients with cardiac arrest, POCUS was most often used to aid decision making with regard to terminating or continuing resuscitation (28 patients; 13.4%). CONCLUSION: During the study period, POCUS examination was used in 34.5% of all prehospital HEMS patients and had a therapeutic consequence in 40.7% of patients. In trauma patients, POCUS seems to be most effective for patient triage and evaluation of treatment effectiveness. Moreover, POCUS can be of significant value in patients undergoing CPR. A tailored HEMS POCUS training curriculum should include ultrasound techniques for trauma and cardiac arrest.

Comparing restrictive versus liberal oxygen strategies for trauma patients - the TRAUMOX2 trial: protocol for a randomised clinical trial.

INTRODUCTION: Supplemental oxygen is commonly used in trauma patients, although it may lead to hyperoxaemia that has been associated with pulmonary complications and increased mortality. The primary objective of this trial, TRAUMOX2, is to compare a restrictive versus liberal oxygen strategy the first 8 hours following trauma. METHODS AND ANALYSIS: TRAUMOX2 is an investigator-initiated, international, parallel-grouped, superiority, outcome assessor-blinded and analyst-blinded, randomised, controlled, clinical trial.Adult patients with suspected major trauma are randomised to eight hours of a restrictive or liberal oxygen strategy. The restrictive group receives the lowest dosage of oxygen (>21%) that ensures an SpO2 of 94%. The liberal group receives 12-15 L O2/min or FiO2=0.6-1.0.The primary outcome is a composite of 30-day mortality and/or development of major respiratory complications (pneumonia and/or acute respiratory distress syndrome).With 710 participants in each arm, we will be able to detect a 33% risk reduction with a restrictive oxygen strategy if the incidence of our primary outcome is 15% in the liberal group. ETHICS AND DISSEMINATION: TRAUMOX2 is carried out in accordance with the Helsinki II Declaration. It has been approved by the Danish Committee on Health Research Ethics for the Capital Region (H-21018062) and The Danish Medicines Agency, as well as the Dutch Medical Research Ethics Committee Erasmus MS (NL79921.078.21 and MEC-2021-0932). A website (www.traumox2.org) is available for updates and study results will be published in an international peer-reviewed scientific journal. TRIAL REGISTRATION NUMBERS: EudraCT 2021-000556-19; NCT05146700.

3D-printed patient specific instruments for corrective osteotomies of the lower extremity.

3D-printing has become a promising adjunct in orthopedic surgery over the past years. A significant drop in costs and increased availability of the required hardware and software needed for using the technique, have resulted in a relatively fast adaptation of 3D-printing techniques for various indications. In this review, the role of 3D-printing for deformity corrections of the lower extremity is described.

Personalized 3D-printed forearm braces as an alternative for a traditional plaster cast or splint; A systematic review.

Forearm fractures such as distal radius fractures are traditionally treated with a plaster or synthetic cast. Patients commonly report inconvenience of the cast, skin problems, and occasionally radial sensory nerve numbness. A known issue with casting is that the rate of secondary dislocation is high. As an alternative to casts, personalized 3D-printed braces are increasingly used. This review provides an inventory of current developments and experience with 3D-printed forearm braces. Main focus was on the design requirements, materials used, technical requirements, and preclinical and clinical results. Review of 12 studies showed that all printed braces used an open design. Fused Deposition Modelling is most commonly used 3D-printing technique (seven studies) and polylactic acid is the most commonly used material (five studies). Clinical evaluation was done in six studies, mainly involving distal radius fractures, and generally showed a low complication rate and high patient satisfaction with the printed brace. Whether or not the results obtained with 3D-printed braces are superior to results after casting requires further studies.

Outcomes after Prehospital Traumatic Cardiac Arrest in the Netherlands: a Retrospective Cohort Study.

BACKGROUND: Traumatic cardiac arrest (TCA) is a severe and life-threatening situation that mandates urgent action. Outcomes after on-scene treatment of TCA in the Netherlands are currently unknown. The aim of the current study was to investigate the rate of survival to discharge in patients who suffered from traumatic cardiac arrest and who were subsequently treated on-scene by the Dutch Helicopter Emergency Medical Services (HEMS). METHODS: A retrospective cohort study was performed including patients ≥ 18 years with TCA for which the Dutch HEMS were dispatched between January 1st 2014 and December 31st 2018. Patients with TCA after hanging, submersion, conflagration or electrocution were excluded. The primary outcome measure was survival to discharge after prehospital TCA. Secondary outcome measures were return of spontaneous circulation (ROSC) on-scene and neurological status at hospital discharge. RESULTS: Nine-hundred-fifteen patients with confirmed TCA were included. ROSC was achieved on-scene in 261 patients (28.5%). Thirty-six (3.9%) patients survived to hospital discharge of which 17 (47.2%) had a good neurological outcome. Age < 70 years (0.7% vs. 5.2%; p=0.041) and a shockable rhythm on first ECG (OR 0.65 95%CI 0.02-0.28; p<0.001) were associated with increased odds of survival. CONCLUSION: Neurologic intact survival is possible after prehospital traumatic cardiac arrest. Younger patients and patients with a shockable ECG rhythm have higher survival rates after TCA. LEVEL OF EVIDENCE: prognostic study, level III.

First attempt success of video versus direct laryngoscopy for endotracheal intubation by ambulance nurses: a prospective observational study.

PURPOSE: The aim of this study was to compare the rate of first attempt success of endotracheal intubation performed by ambulance nurses in patients with a Glasgow Coma Scale (GCS) of 3 using video laryngoscopy versus direct laryngoscopy. METHODS: A prospective cohort study was conducted in a single, independent ambulance service. Twenty of a total of 65 nurse-staffed ambulances were equipped with a video laryngoscope; a classic direct laryngoscope (Macintosh) was available on all 65 ambulances. The primary outcome was first attempt success of the intubation. Secondary outcomes were overall success, time needed for intubation, adverse events, technical or environmental issues encountered, and return of spontaneous circulation (ROSC). Ambulance nurses were asked if the intubation device had affected the outcome of the intubation. RESULTS: The first attempt success rate in the video laryngoscopy group [53 of 93 attempts (57%)] did not differ from that in the direct laryngoscopy group [61 of 126 (48%); p = 0.221]. However, the second attempt success rate was higher in the video laryngoscopy group [77/93 (83%) versus 80/126 (63%), p = 0.002]. The median time needed for the intubation (53 versus 56 s) was similar in both groups. Ambulance nurses more often expected a positive effect when performing endotracheal intubation with a video laryngoscope (n = 72, 81%) compared with a direct laryngoscope (n = 49, 52%; p < 0.001). CONCLUSION: Although no significant effect on the first attempt success was found, video laryngoscopy did increase the overall success rate. Ambulance nurses had a more positive valuation of the video laryngoscope with respect to success chances.

Decision making in prehospital traumatic cardiac arrest; A qualitative study.

BACKGROUND: Despite improving survival of patients in prehospital traumatic cardiac arrest (TCA), initiation and/or discontinuation of resuscitation of TCA patients remains a subject of debate among prehospital emergency medical service providers. The aim of this study was to identify factors that influence decision making by prehospital emergency medical service providers during resuscitation of patients with TCA. METHODS: Twenty-five semi-structured interviews were conducted with experienced ambulance nurses, HEMS nurses and HEMS physicians individually, followed by a focus group discussion. Participants had to be currently active in prehospital medicine in the Netherlands. Interviews were encoded for analysis using ATLAS.ti. Using qualitative analysis, different themes around decision making in TCA were identified. RESULTS: Eight themes were identified as being important factors for decision making during prehospital TCA. These themes were: (1) factual information (e.g., electrocardiography rhythm or trauma mechanism); (2) fear of providing futile care or major impairment if return of spontaneous circulation was obtained; (3) potential organ donation; (4) patient age; (5) suspicion of attempted suicide; (6) presence of bystanders or family; (7) opinions of other team members; and (8) training and education. Several ambulance nurses reported they do not feel adequately supported by the current official national ambulance guidelines on TCA, nor did they feel sufficiently trained to perform pre-hospital interventions such as endotracheal intubation or needle thoracocentesis on these patients. CONCLUSION: Eight themes were identified as being important for decision making during prehospital TCA. While guidelines based on prognostic factors are important, it should be recognized that decision making in TCA is impacted by more than factual information alone. This should be reflected in educational programs and future guidelines.

Patterns of injury and outcomes in the elderly patient with rib fractures: a multicenter observational study.

BACKGROUND: High rates of pneumonia and death have been reported among elderly patients with rib fractures. This study aims to identify patterns of injury and risk factors for pneumonia and death in elderly patients with rib fractures. METHODS: A retrospective multicenter observational study was performed using data registered in the national trauma registry between 2008 and 2015 in the South West Netherlands Trauma region. Data regarding demographics, mechanism of injury, pulmonary and cardiovascular history, pattern of extra-thoracic and intrathoracic injuries, ICU admission, length of stay, and morbidity and mortality following admission were collected. RESULTS: Eight hundred eighty-four patients were included. Median age was 76 years (P25-P75 70-83). 235 patients (26.6%) were 81 years or older. Moderate or worse extra-thoracic injuries were present in 456 patients (51.6%), of whom 146 (16.6%) had severe head injuries and 45 (5.1%) severe spinal injuries. Median ISS was 9 (P25-P75 5-18). The rate of pneumonia was 10% (n = 84). Ten percent of patients (n = 88) died. Risk factors for in-hospital mortality included age (OR 3.4; p = 0.003), presence of COPD (OR 1.3; p = 0.01), presence of cardiac disease (OR 2.6; p = 0.003), severe or worse head (OR 3.5; p < 0.001), abdominal (OR 6.8; p = 0.004) and spinal injury (OR 4.6; p = 0.011) by AIS, number of rib fractures (OR 2.6; p = 0.03), and need for chest tube drainage (OR 2.1; p = 0.021). CONCLUSIONS: Pneumonia and death occur in about 10% of elderly patients with rib fractures. Apart from the severity of thoracic injuries, the presence and severity of extra-thoracic injuries and cardiopulmonary comorbidities are associated with poor outcome.

Out of hospital thoracotomy for cardiac arrest after penetrating thoracic trauma.

INTRODUCTION: Emergency department thoracotomy is an established procedure for cardiac arrest in patients suffering from penetrating thoracic trauma and yields relatively high survival rates (up to 21%) in patients with cardiac tamponade. To minimize the delay between arrest and thoracotomy, some have advocated thoracotomy on the accident scene. The aim of this study was to determine the proportion of patients with return of spontaneous circulation and subsequent survival after out of hospital thoracotomy in the Netherlands. METHODS: A retrospective analysis of data collected on all out of hospital thoracotomies performed in the Netherlands after penetrating trauma between April 1st, 2011 and September 30th, 2016 was performed. Data on patient characteristics, trauma mechanism and outcome were collected and analyzed. Primary outcome measure was return of spontaneous circulation after the intervention. Survival to hospital discharge was the secondary outcome variable. RESULTS: Thirty-three prehospital emergency thoracotomies were performed. Ten patients (30%) had gunshot wounds and 23 patients (70%) had stab wounds. Nine patients (27%) had return of spontaneous circulation and were presented to the hospital. Of these, one patient survived until discharge without neurological damage. Five died in the emergency department or operating room and three died in ICU. CONCLUSION: Return of spontaneous circulation after out of hospital thoracotomy for cardiac arrest due to penetrating thoracic injury is achievable, but a substantial number of patients die during the in hospital resuscitation phase. However, neurologic intact survival can be achieved.

Transanal endoscopic surgery for complications of prior rectal surgery.

BACKGROUND: Long-term complications of previous rectal surgery (e.g., enterovisceral fistula, anastomotic stricture, rectal stenosis) can be challenging problems for which transabdominal or transperineal surgery with or without definitive fecal diversion is often required. Transanal endoscopic surgery (TES) might allow for local treatment of these complications, thereby saving patients from otherwise major surgery. PATIENTS AND METHODS: All patients undergoing TES in the IJsselland Hospital (NL) since 1996 were recorded in a prospective database, of which twenty patients were treated for complications after previous rectal surgery. Data on prior treatment, surgical techniques, outcomes, and need for additional surgery were collected. RESULTS: Twenty patients were identified from the database (rectourinary fistula n = 3, rectovaginal fistula n = 5, anastomotic stricture n = 8, and rectal stenosis n = 4). One of the three (33 %) rectourinary fistulas and two of five (40 %) rectovaginal fistulas were successfully treated with TES. Anastomotic strictures were successfully treated in 5/8 (63 %) patients. Strictures after local excision of rectal tumors were successfully treated in 3/4 (75 %) patients. No minor complication and one major complication occurred (rectovaginal fistula after stenoplasty eventually requiring Hartmann's procedure). CONCLUSIONS: Transanal treatment of anastomotic strictures, rectal stenosis, and fistula after prior rectal surgery is safe and effective in a large proportion of patients. TES should be considered as a first step in all patients presenting with these late complications after rectal surgery.

Sarcopenia impairs survival in patients with potentially curable hepatocellular carcinoma.

BACKGROUND: A reduction in skeletal muscle mass (sarcopenia) independently predicts poor survival in patients with hepatocellular carcinoma (HCC) undergoing treatment with curative intent. Whether this is due to an increased risk of recurrence and disease specific death, or due to an increased risk of postoperative morbidity and mortality is currently unclear. In this study, we investigate the association between sarcopenia and death in a cohort of HCC patients undergoing treatment with curative intent. METHODS: Patients undergoing surgical resection or radiofrequency ablation for lesions ≤ 3 cm between 2002 and 2013 were identified. Clinicopathological characteristics, CT-assessed sarcopenia and outcomes were analyzed. RESULTS: Among 90 patients, 52 (57.8%) were found to be sarcopenic. Sarcopenic patients had a limited overall survival (median: 33 months vs. non-sarcopenic median: 105 months; P = 0.002), but not disease-free survival. Sarcopenia was an independent predictor for overall survival in multivariate Cox-regression analysis (HR 3.756; P = 0.001). Major complications (32.7% vs. 13.2%, P = 0.033) and treatment-related mortality (17.3% vs. 2.6%, P = 0.029) were more frequent in sarcopenic patients. CONCLUSION: Sarcopenia impairs survival in patients with potentially curable hepatocellular carcinoma, mainly due to an increase in treatment-related mortality.

[The elderly patient with multiple rib fractures]. / De oudere patiënt met multipele ribfracturen.

Rib fractures resulting from blunt thoracic trauma occur frequently in the elderly. Even though these are usually due to a low impact trauma mechanism (e.g. a fall from standing height), rib fractures are associated with significant morbidity and mortality in the elderly patient. This unfavourable clinical course is most often caused by respiratory insufficiency due to lung oedema or pneumonia. This cases series presents three elderly patients who sustained multiple rib fractures and were subsequently admitted to a level I trauma centre for treatment and discusses diagnostic challenges and different treatment approaches for this population. More specifically, age-specific indications and contra-indications for intravenous or epidural analgesia and operative rib fixation are discussed. In addition, we show that a multidisciplinary approach, involving a trauma surgeon, anaesthetist, intensive care physician and physiotherapist, is paramount for the prevention of potentially lethal complications.

A freehand ultrasound elastography system with tracking for in vivo applications.

Ultrasound transducers are commonly tracked in modern ultrasound navigation/guidance systems. In this article, we demonstrate the advantages of incorporating tracking information into ultrasound elastography for clinical applications. First, we address a common limitation of freehand palpation: speckle decorrelation due to out-of-plane probe motion. We show that by automatically selecting pairs of radio frequency frames with minimal lateral and out-of-plane motions, combined with a fast and robust displacement estimation technique, greatly improves in vivo elastography results. We also use tracking information and image-quality measures to fuse multiple images with similar strains that are taken from roughly the same location so as to obtain a high-quality elastography image. Finally, we show that tracking information can be used to give the user partial control over the rate of compression. Our methods are tested on a tissue-mimicking phantom, and experiments have been conducted on intraoperative data acquired during animal and human experiments involving liver ablation. Our results suggest that in challenging clinical conditions, our proposed method produces reliable strain images and eliminates the need for a manual search through the ultrasound data in order to find radio frequency pairs suitable for elastography.

Behavior of tip-steerable needles in ex vivo and in vivo tissue.

Robotic needle steering is a promising technique to improve the effectiveness of needle-based clinical procedures, such as biopsies and ablation, by computer-controlled, curved insertions of needles within solid organs. In this paper, we explore the capabilities, challenges, and clinical relevance of asymmetric-tip needle steering through experiments in ex vivo and in vivo tissue. We evaluate the repeatability of needle insertion in inhomogeneous biological tissue and compare ex vivo and in vivo needle curvature and insertion forces. Steerable needles curved more in kidney than in liver and prostate, likely due to differences in tissue properties. Pre-bent needles produced higher insertion forces in liver and more curvature in vivo than ex vivo. When compared to straight stainless steel needles, steerable needles did not cause a measurable increase in tissue damage and did not exert more force during insertion. The minimum radius of curvature achieved by prebent needles was 5.23 cm in ex vivo tissue, and 10.4 cm in in vivo tissue. The curvatures achieved by bevel tip needles were negligible for in vivo tissue. The minimum radius of curvature for bevel tip needles in ex vivo tissue was 16.4 cm; however, about half of the bevel tip needles had negligible curvatures. We also demonstrate a potential clinical application of needle steering by targeting and ablating overlapping regions of cadaveric canine liver.