Acinetobacter infections: a retrospective study to determine inhospital mortality rate and clinical factors associated with mortality.

A retrospective case series of acinetobacter infections at a tertiary hospital in Nairobi was conducted to determine the mortality rate and factors associated with mortality. Over an eight-year period, 80 clinically significant infections were identified. The majority of infections were ventilator-associated pneumonia (40%) and bloodstream infections (30%). Eighty-six percent of the isolates were multi-drug resistant. The mortality rate in the study cohort was 45%. Twelve patients grew Acinetobacter spp. within 48 h of hospitalization, and three of these patients had no prior healthcare contact. The mean Sequential Organ Failure Assessment score was associated with mortality from acinetobacter infections.

Serum metabolic and minerals profile in norgestomet primed postpartum anestrous surti buffaloes.

AIM: The study was undertaken to find out the serum metabolic and minerals profile in postpartum anestrous surti buffaloes treated with norgestomet ear implants alone and in combination with pregnant mare serum gonadotropin (PMSG). MATERIALS AND METHODS: The study was conducted on 18 postpartum anestrous Surti buffaloes divided into three groups of six animals each at random to conduct the experiment. The buffaloes in Group-I and Group-II were implanted with Crestar ear implant for 9 days together with 2 ml injection of Crestar solution given i/m on the day of the implant insertion. In Group-II, additionally 500 IU PMSG was given i/m on the day of implant removal, whereas the buffaloes in Group-III served as anestrous control group and received 5 ml Normal Saline i/m on day 0 and 9 as a placebo treatment. RESULTS: The overall serum total protein values did not differ significantly (p > 0.05) between time (days) intervals in any of the groups. The mean serum total cholesterol levels at 10(th) day and on the day of estrus were found significantly lower (p < 0.05) in the control group as compared to treatment Groups I and II. However, there was no significant difference (p > 0.05) at 10(th) day and on the day of estrus between treatment groups (T1 and T2). The overall mean serum cobalt, zinc, iron, and manganese values did not differ significantly (p > 0.05) between different time intervals among any of the groups, except copper which was significantly lower (p < 0.05) at 10(th) day in control group as compared to treatment groups. CONCLUSION: Microelements cannot be synthesized in the body. Hence, it is concluded that the mineral mixture should be supplied daily in the animals ration to suffice the requirement of the trace elements. The mean serum metabolic and micro-minerals profiles in treatment and control groups revealed that overall mean serum total protein, cholesterol, copper, and zinc levels were apparently higher in treatment groups whereas, mean serum cobalt, iron, and manganese concentration had no consistent trend between treatment and control groups of Surti buffaloes.

A semi-infinite programming approach to preoperative planning of robotic cardiac surgery under geometric uncertainty.

In this paper, a computational framework for patient-specific preoperative planning of Robotics-Assisted Minimally Invasive Cardiac Surgery (RAMICS) is presented. It is expected that preoperative planning of RAMICS will improve the success rate by considering robot kinematics, patient-specific thoracic anatomy, and procedure-specific intraoperative conditions. Given the significant anatomical features localized in the preoperative computed tomography images of a patients thorax, port locations and robot orientations (with respect to the patients body coordinate frame) are determined to optimize qualities such as dexterity, reachability, tool approach angles and maneuverability. To address intraoperative geometric uncertainty, the problem is formulated as a Generalized Semi-Infinite Program (GSIP) with a convex lower-level problem to seek a plan that is less sensitive to geometric uncertainty in the neighborhood of surgical targets. It is demonstrated that with a proper formulation of the problem, the GSIP can be replaced by a tractable constrained nonlinear program that uses a multi-criteria objective function to balance between the nominal task performance and robustness to collisions and joint limit violations. Finally, performance of the proposed formulation is demonstrated by a comparison between the plans generated by the algorithm and those recommended by an experienced surgeon for several case studies.

Integration of force reflection with tactile sensing for minimally invasive robotics-assisted tumor localization.

Tactile sensing and force reflection have been the subject of considerable research for tumor localization in soft-tissue palpation. The work presented in this paper investigates the relevance of force feedback (presented visually as well as directly) during tactile sensing (presented visually only) for tumor localization using an experimental setup close to one that could be applied for real robotics-assisted minimally invasive surgery. The setup is a teleoperated (master-slave) system facilitated with a state-of-the-art minimally invasive probe with a rigidly mounted tactile sensor at the tip and an externally mounted force sensor at the base of the probe. The objective is to capture the tactile information and measure the interaction forces between the probe and tissue during palpation and to explore how they can be integrated to improve the performance of tumor localization. To quantitatively explore the effect of force feedback on tactile sensing tumor localization, several experiments were conducted by human subjects to locate artificial tumors embedded in the ex vivo bovine livers. The results show that using tactile sensing in a force-controlled environment can realize, on average, 57 percent decrease in the maximum force and 55 percent decrease in the average force applied to tissue while increasing the tumor detection accuracy by up to 50 percent compared to the case of using tactile feedback alone. The results also show that while visual presentation of force feedback gives straightforward quantitative measures, improved performance of tactile sensing tumor localization is achieved at the expense of longer times for the user. Also, the quickness and intuitive data mapping of direct force feedback makes it more appealing to experienced users.

A fast torsionally compliant kinematic model of concentric-tube robots.

Concentric-tube robots have the potential to become an important surgical tool for robot-assisted percutaneous interventions. They can provide dexterous operation in a small constrained environment. The kinematic model of a concentric-tube robot has been well developed in terms of accuracy, but the computational cost places limitations on real-time implementation. In this paper, we propose a new technique that will substantially improve the computational efficiency of evaluating the kinematics of a concentric-tube robot in the context of developing a control strategy without sacrificing the accuracy of the results. In this paper we develop a torsionally compliant kinematic model using global variables. The model is validated by comparing the results obtained by computing the kinematic model corresponding to an experimental setup of a concentric-tube robot to which a force/torque sensor has been mounted at its base with those obtained directly from the experimental setup. The results indicate that it is feasible to compute the kinematics of the concentric-tube robot fast enough to allow the position/force control loop to be implemented at a rate of 1 kHz.

Optimal transseptal puncture location for robot-assisted left atrial catheter ablation.

BACKGROUND: The preferred method of treatment for atrial fibrillation (AF) is by catheter ablation, in which a catheter is guided into the left atrium through a transseptal puncture. However, the transseptal puncture constrains the catheter, thereby limiting its manoeuvrability and increasing the difficulty in reaching various locations in the left atrium. In this paper, we address the problem of choosing the optimal transseptal puncture location for performing cardiac ablation to obtain maximum manoeuvrability of the catheter. METHODS: We have employed an optimization algorithm to maximize the global isotropy index (GII) to evaluate the optimal transseptal puncture location. As part of this algorithm, a novel kinematic model for the catheter has been developed, based on a continuum robot model. Pre-operative MR/CT images of the heart are segmented using the open source image-guided therapy software, 3D Slicer, to obtain models of the left atrium and septal wall. These models are input to the optimization algorithm to evaluate the optimal transseptal puncture location. RESULTS: The continuum robot model accurately describes the kinematics of the catheter. Simulation and experimental results for the optimal transseptal puncture location are presented in this paper. The optimization algorithm generates discrete points on the septal wall for which the dexterity of the catheter in the left atrium is maximum, corresponding to a GII of 0.4362. CONCLUSION: We have developed an optimization algorithm based on the GII to evaluate the optimal position of the transseptal puncture for left atrial cardiac ablation.

Toward construct validity for a novel sensorized instrument-based minimally invasive surgery simulation system.

Minimally invasive surgical training is complicated due to the constraints imposed by the surgical environment. Sensorized laparoscopic instruments capable of sensing force in five degrees of freedom and position in six degrees of freedom were evaluated. Novice and expert laparoscopists performed the complex minimally invasive surgical task of suturing using the novel instruments. Their force and position profiles were compared. The novel minimally invasive surgical instrument proved to be construct valid and capable of detecting differences between novices and experts in a laparoscopic suturing task with respect to force and position. Further evaluation is mandated for a better understanding of the ability to predict performance based on force and position as well as the potential for new metrics in minimally invasive surgical education.

New tactile sensing system for minimally invasive surgical tumour localization.

BACKGROUND: Minimally invasive surgery (MIS) suffers from the inability to directly palpate organs for tumour localization. A tactile sensing system (TSS), consisting of a probe and a visualization interface, was developed to present an active pressure map of the contact surface to locate tumours during MIS. METHODS: The TSS performance was compared to MIS graspers to locate occult 10 mm phantom tumours in ex vivo bovine liver and ex vivo porcine lung. Performance assessment included applied pressure, localization distance and accuracy. RESULTS: The TSS realized a relative 71% reduction in maximum applied pressure and a 31% increase in detection accuracy in liver tissue (when compared to MIS graspers) and demonstrated no significant differences in performance when palpating lung tissue. CONCLUSIONS: The TSS may help surgeons to identify occult tumours during surgery by restoring some of the haptic information lost during MIS.

Revision arthroscopic capsulolabral reconstruction for recurrent instability of the shoulder.

We have investigated the outcome of arthroscopic revision surgery for recurrent instability of the shoulder after failed primary anterior stabilisation. We identified 40 patients with failed primary open or arthroscopic anterior stabilisation of the shoulder who had been treated by revision arthroscopic capsulolabral reconstruction and followed up for a mean of 36 months (12 to 87). There were 34 men and six women with a mean age of 33.1 years (15 to 48). Details of the patients, the technique of the primary procedure, the operative findings at revision and the clinical outcome were evaluated by reviewing the medical records, physical examination and the use of the Western Ontario shoulder instability index score, the American Shoulder and Elbow Surgeons score and the health status questionnaire 12. Recurrent instability persisted in four patients after the revision arthroscopic procedure. At the final follow-up, the mean American Shoulder and Elbow Surgeons score was 81.1 (17.5 to 99.5) and the mean Western Ontario shoulder instability index score was 68.2 (20 to 98.2). Quality-of-life scoring showed good to excellent results in most patients. Arthroscopic revision capsulolabral reconstruction can provide a satisfactory outcome in selected patients for recurrent instability of the shoulder provided that no large Hill-Sachs lesion is present.

Electromagnetic navigation improves minimally invasive robot-assisted lung brachytherapy.

OBJECTIVE: Recent advances in minimally invasive thoracic surgery have renewed an interest in the role of interstitial brachytherapy for lung cancer. Our previous work has demonstrated that a minimally invasive robot-assisted (MIRA) lung brachytherapy system produced results that were equal to or better than those obtained with standard video-assisted thoracic surgery (VATS) and comparable to results with open surgery. The purpose of this project was to evaluate the performance of an integrated system for MIRA lung brachytherapy that incorporated modified electromagnetic navigation and ultrasound image guidance with robotic assistance. METHODS: The experimental test-bed consisted of a VATS box, ZEUS and AESOP surgical robotic arms, a seed injector, an ultrasound machine, video monitors, a computer, and an endoscope. Our previous custom-designed electromagnetic navigational software and the robotic controller were modified and incorporated into the MIRA III system to become the next-generation MIRA IV. Inactive brachytherapy seeds were injected as close as possible to a small metal ball target embedded in an opaque agar cube. The completion time, the number of attempts, and the accuracy of seed deployment were compared for manual placement, standard VATS, MIRA III, and the new MIRA IV system. RESULTS: The MIRA IV system significantly reduced the median procedure time by 61% (104 s to 41 s), tissue trauma by 75% (4 attempts to 1 attempt), and mean seed placement error by 64% (2.5 mm to 0.9 mm) when compared to a standard VATS. MIRA IV also reduced the mean procedure time by 48% (85 s to 44 s) and the seed placement error by 68% (2.8 mm to 0.9 mm) compared to the MIRA III system. CONCLUSIONS: A modified integrated system for performing minimally invasive robot-assisted lung brachytherapy was developed that incorporated electromagnetic navigation and an improved robotic controller. The MIRA IV system performed significantly better than standard VATS and better than MIRA III.

Feasibility of locating tumours in lung via kinaesthetic feedback.

BACKGROUND: Localizing lung tumours during minimally invasive surgery is difficult, since restricted access precludes manual palpation and pre-operative imaging cannot map directly to the intra-operative lung. This study analyses the force-sensing performance that would allow an instrumented kinaesthetic probe to localize tumours based on stiffness variations of the lung parenchyma. METHODS: Agar injected into ex vivo porcine lungs produced a model approximating commonly encountered tumours. Force-deformation data were collected from multiple sites at various palpation depths and velocities, before and after the tumours were injected. RESULTS: Analysis showed an increase in force after the tumours were injected, in the range 0.07-0.16 N at 7 mm (p < 10(-4)). A 2 mm/s palpation velocity minimized exponential stress decay at constant depths, facilitating easier comparisons between measurements. CONCLUSION: A sensing range of 0-2 N, with 0.01 N resolution, should allow a kinaesthetic palpation probe to resolve local tissue stiffness changes that suggest an underlying tumour.

Optimizing port placement for robot-assisted minimally invasive cardiac surgery.

BACKGROUND: Proper placement of ports during robot-assisted endoscopic surgery is critical to the success of the procedure. In current practice, port placement methods do not consider the ability of the robot to manoeuvre the tools. METHODS: This paper proposes to choose the best port location such that the performance of the robot is maximized. The Global Conditioning Index (GCI) is used to optimize port placement when using the da Vinci((R)) surgical system during cardiac surgery. RESULTS: The results show that, due to a singularity at the remote centre of motion, higher performance is obtained the further away the port is from the workspace. When compared to the ports selected by an expert surgeon, our results show that it is possible to increase robot performance by at least 29% for the left arm of the robot. CONCLUSIONS: Selecting an adequate port location can improve robot performance and ensure that the instruments reach the surgical site.

Robot-assisted minimally invasive lung brachytherapy.

BACKGROUND: This paper presents a novel alternative for the treatment of lung cancer. The method consists of accessing the lung through small incisions in a minimally invasive manner in order to insert radioactive seeds directly into the lung using a robotic surgical system. METHODS: An experimental test-bed to evaluate the feasibility of this approach has been developed. It consists of two surgical robotic systems, a device specifically designed to robotically implant radioactive seeds, needle tracking software, ultrasound imaging, electromagnetic tracking, and a surgical box that mimics a patient's thorax. A detailed comparison has been performed between currently available access options and robot-assisted minimally invasive access. RESULTS: The results show insignificant differences in accuracy between the methods, with the exception of a significant improvement when electromagnetic (EM) guidance was added to the non-robotic techniques. The navigation system reduced the number of attempts for all seed delivery methods. Significant reductions in time were achieved in the minimally invasive procedures by the addition of EM guidance. CONCLUSIONS: The performance achieved when using robotic systems and image guidance for minimally-invasive brachytherapy is clinically comparable to that achieved in an open surgery procedure, while reducing the invasiveness of the procedure, improving ergonomic conditions for the clinician and reducing radiation exposure.