Jaishankar Raman

Adverse Events in Robotic Surgery: A Retrospective Study of 14 Years of FDA Data.

Background Use of robotic systems for minimally invasive surgery has rapidly increased during the last decade. Understanding the causes of adverse events and their impact on patients in robot-assisted surgery will help improve systems and operational practices to avoid incidents in the future. Methods By developing an automated natural language processing tool, we performed a comprehensive analysis of the adverse events reported to the publicly available MAUDE database (maintained by the U.S. Food and Drug Administration) from 2000 to 2013. We determined the number of events reported per procedure and per surgical specialty, the most common types of device malfunctions and their impact on patients, and the potential causes for catastrophic events such as patient injuries and deaths. Results During the study period, 144 deaths (1.4% of the 10,624 reports), 1,391 patient injuries (13.1%), and 8,061 device malfunctions (75.9%) were reported. The numbers of injury and death events per procedure have stayed relatively constant (mean = 83.4, 95% confidence interval (CI), 74.2–92.7 per 100,000 procedures) over the years. Surgical specialties for which robots are extensively used, such as gynecology and urology, had lower numbers of injuries, deaths, and conversions per procedure than more complex surgeries, such as cardiothoracic and head and neck (106.3 vs. 232.9 per 100,000 procedures, Risk Ratio = 2.2, 95% CI, 1.9–2.6). Device and instrument malfunctions, such as falling of burnt/broken pieces of instruments into the patient (14.7%), electrical arcing of instruments (10.5%), unintended operation of instruments (8.6%), system errors (5%), and video/imaging problems (2.6%), constituted a major part of the reports. Device malfunctions impacted patients in terms of injuries or procedure interruptions. In 1,104 (10.4%) of all the events, the procedure was interrupted to restart the system (3.1%), to convert the procedure to non-robotic techniques (7.3%), or to reschedule it (2.5%). Conclusions Despite widespread adoption of robotic systems for minimally invasive surgery in the U.S., a non-negligible number of technical difficulties and complications are still being experienced during procedures. Adoption of advanced techniques in design and operation of robotic surgical systems and enhanced mechanisms for adverse event reporting may reduce these preventable incidents in the future.

Sternal Closure With Rigid Plate Fixation Versus Wire Closure: A Randomized Controlled Multicenter Trial

BACKGROUND Rigid bone fixation is the standard of care for all bone reconstructions except that after sternotomy. Sternal reconstruction after median sternotomy using rigid fixation with plates may improve bone healing and reduce pain when compared with wire cerclage. METHODS One-hundred forty patients at six centers who were determined preoperatively to be at high risk for sternal wound complications were randomly assigned to sternal closure with rigid plate fixation (n=70) or wire cerclage (n=70). Sternal healing was evaluated at 3 or 6 months by a core laboratory using computed tomography. Pain and function were evaluated at postoperative day 3 through discharge, 3 weeks, 6 weeks, 3 months, and 6 months. RESULTS Sternal healing was superior in rigid plate fixation patients at both 3 and 6 months. Mean computed tomography scores in the rigid plate fixation and wire cerclage groups at 3 months were 1.7±1.1 and 0.9±0.8 (p=0.003). At 6 months, the scores were 3.2±1.6 and 2.2±1.1, respectively (p=0.01). At 6 months, 70% of rigid plate fixation patients had achieved sternal union, compared with 24% of conventional wire cerclage patients (p=0.003). Pain scores and narcotic usage were lower in rigid plate fixation patients. Significant differences in pain scores were observed at 3 weeks for total pain (p=0.020) and pain with coughing (p=0.0084) or sneezing (p=0.030). Complication rates were similar in both groups. CONCLUSIONS Sternal reconstruction using rigid fixation with plates improved bone healing and reduced early postoperative pain compared with wire cerclage.

Systems-Theoretic Safety Assessment of Robotic Telesurgical Systems

Robotic surgical systems are among the most complex medical cyber-physical systems on the market. Despite significant improvements in design of those systems through the years, there have been ongoing occurrences of safety incidents that negatively impact patients during procedures. This paper presents an approach for systems-theoretic safety assessment of robotic telesurgical systems using software-implemented fault injection. We used a systems-theoretic hazard analysis technique STPA to identify the potential safety hazard scenarios and their contributing causes in RAVEN II, an open-source telerobotic surgical platform. We integrated the robot control software with a software-implemented fault injection engine that measures the resilience of system to the identified hazard scenarios by automatically inserting faults into different parts of the software. Representative hazard scenarios from real robotic surgery incidents reported to the U.S. Food and Drug Administration FDA MAUDE database were used to demonstrate the feasibility of the proposed approach for safety-based design of robotic telesurgical systems.

Evaluation of Sternal Bone Healing with Computed Tomography and a Quantitative Scoring Algorithm

Objective: The exquisite bone detail offered by computed tomography makes it the ideal modality for evaluation of bone healing. However, few studies have investigated the normal computed tomographic appearance of the sternum after median sternotomy and, to the best of our knowledge, no computed tomographic classification of sternal healing has been proposed. Given the potential benefit of objective criteria, we propose a validated scoring classification of sternal healing using computed tomography for both clinical and investigational purposes. Methods: Computed tomography scans from 20 patients who underwent a median sternotomy were evaluated for sternal healing at either 3 or 6 months postoperatively. Five anatomic locations along the sternum were selected using defined criteria, and a 6-point quantitative scale was developed to evaluate sternal healing. Independent radiologists read and scored each of the 5 locations on the sternum. Inter- and intra-observer variability was assessed by calculating the kappa statistics to measure the reliability of the scoring algorithm. Results: Calculation of the kappa statistics indicated substantial agreement for intra-observer variability and substantial to almost perfect agreement for inter-observer variability. For intra-observer variability, the kappa statistics ranged from 0.591 to 0.802, and for inter-observer variability, the kappa statistics ranged from 0.590 to 0.969. When the two radiologists differed, the magnitude of the difference was no more than 1 or 2 points. Conclusion: This simple system of evaluating sternal healing had high inter- and intra-observer reliability. Therefore, it may be considered a valid method for assessing sternal osteosynthesis for both clinical and investigative purposes. Ultramini abstract: (49 words): Few studies have investigated the normal computed tomography appearance of the sternum after median sternotomy, and we knew of no computed tomography-based classification of sternal healing. Given the potential benefit of objective criteria, we designed and validated a scoring classification of sternal osteosynthesis for both clinical and investigational purposes.

Lung transplant outcome prediction using UNOS data

We analyze lung transplant data from the United Network for Organ Sharing (UNOS) program with the aim of developing accurate risk prediction models for mortality within 1 year of lung transplant using data mining techniques. The data used in this study is de-identified and consists of 62 predictor attributes, and 1-year posttranplant survial outcome for patients who underwent lung transplant between the years 2005 and 2009. Our dataset had 5,319 such patient instances. Several data mining classification techniques were used on this data along with various data mining optimizations and validations to build predictive models for the abovementioned outcome. Prediction results were evaluated using c-statistic metric, and the highest c-statistic obtained was 0.68. Further, we also applied feature selection techniques to reduce the number of attributes in the model from 50 to 8, without any degradation in c-statistic. The final model was also found to outperform logistic regression, which is the most commonly used technique in predictive healthcare informatics. We believe that the resulting predictive model on the reduced dataset can be quite useful to integrate in a risk calculator to aid both physicians and patients in risk assessment.

Complex Tricuspid Valve Repair in Patients With Pacer Defibrillator-Related Tricuspid Regurgitation.

Tricuspid valve regurgitation in patients with heart failure or in those undergoing complex cardiac operations is associated with increased morbidity and mortality. We report our results with a technique of repairing the tricuspid valves while retaining the pacer defibrillator lead. Patients had tricuspid valve repairs that included repositioning of the pacer defibrillator lead, approximation of septal and inferior/posterior leaflets in a modified cleft repair, and implantation of a tricuspid annuloplasty ring. This procedure was performed in more than 42 patients with good success.

Computational chemical imaging for cardiovascular pathology: Chemical microscopic imaging accurately determines cardiac transplant rejection

Rejection is a common problem after cardiac transplants leading to significant number of adverse events and deaths, particularly in the first year of transplantation. The gold standard to identify rejection is endomyocardial biopsy. This technique is complex, cumbersome and requires a lot of expertise in the correct interpretation of stained biopsy sections. Traditional histopathology cannot be used actively or quickly during cardiac interventions or surgery. Our objective was to develop a stain-less approach using an emerging technology, Fourier transform infrared (FT-IR) spectroscopic imaging to identify different components of cardiac tissue by their chemical and molecular basis aided by computer recognition, rather than by visual examination using optical microscopy. We studied this technique in assessment of cardiac transplant rejection to evaluate efficacy in an example of complex cardiovascular pathology. We recorded data from human cardiac transplant patients’ biopsies, used a Bayesian classification protocol and developed a visualization scheme to observe chemical differences without the need of stains or human supervision. Using receiver operating characteristic curves, we observed probabilities of detection greater than 95% for four out of five histological classes at 10% probability of false alarm at the cellular level while correctly identifying samples with the hallmarks of the immune response in all cases. The efficacy of manual examination can be significantly increased by observing the inherent biochemical changes in tissues, which enables us to achieve greater diagnostic confidence in an automated, label-free manner. We developed a computational pathology system that gives high contrast images and seems superior to traditional staining procedures. This study is a prelude to the development of real time in situ imaging systems, which can assist interventionists and surgeons actively during procedures.

Rigid plate fixation promotes better bone healing after sternotomy.

Sternotomy is the most common surgically created osteotomy in surgery. Rigid fixation of osteotomies are important for stability and bony union. This review shows the superiority of rigid plate fixation in achieving better bone healing after sternotomy. It also highlights use of plate fixation for mini-sternotomies and rib fractures.

The arrowhead ministernotomy with rigid sternal plate fixation: a minimally invasive approach for surgery of the ascending aorta and aortic root.

Background. Ministernotomy incisions have been increasingly used in a variety of settings. We describe a novel approach to ministernotomy using arrowhead incision and rigid sternal fixation with a standard sternal plating system. Methods. A small, midline, vertical incision is made from the midportion of the manubrium to a point just above the 4th intercostal mark. The sternum is opened in the shape of an inverted T using two oblique horizontal incisions from the midline to the sternal edges. At the time of chest closure, the three bony segments are aligned and approximated, and titanium plates (Sternalock, Jacksonville, Florida) are used to fix the body of the sternum back together. Results. This case series includes 11 patients who underwent arrowhead ministernotomy with rigid sternal plate fixation for aortic surgery. The procedures performed were axillary cannulation (n = 2), aortic root replacement (n = 3), valve sparing root replacement (n = 3), and replacement of the ascending aorta (n = 11) and/or hemiarch (n = 2). Thirty-day mortality was 0%; there were no conversions, strokes, or sternal wound infections. Conclusions. Arrowhead ministernotomy with rigid sternal plate fixation is an adequate minimally invasive approach for surgery of the ascending aorta and aortic root.

Early complications of biologic extracellular matrix patch after use for femoral artery repair

Background: The CorMatrix (CorMatrix Cardiovascular, Roswell, Ga) biologic extracellular patch derived from porcine small intestinal mucosa provides a biologic scaffold for cellular ingrowth and eventual tissue regeneration. It has been used in a variety of applications, including cardiac and vascular repair procedures. Methods: CorMatrix was used as a patch arterioplasty for femoral artery repair in conjunction with endarterectomy for seven separate procedures in six patients (one patient underwent staged, bilateral femoral procedures). Results: Patients were a median age of 67 years (interquartile range, 3.6 years). Six of seven procedures (86%) were performed on male patients. There were no operative deaths. Three of seven procedures (43%) resulted in significant early complications. Two procedures (29%) resulted in catastrophic biologic extracellular matrix patch disruption (11 and 19 days after initial procedure), requiring emergency exploration, patch removal, and definitive repair with vein patch arterioplasty. Both patches demonstrated an absence of growth on culture. One procedure (14%) resulted in groin pseudoaneurysm formation. Use of the CorMatrix patch was suspended upon recognition of significant complications. Conclusions: Use of CorMatrix patch in the femoral artery position demonstrates a high incidence of early postoperative complications, including catastrophic patch disruption and pseudoaneurysm formation.