A Force-Feedback Methodology for Teleoperated Suturing Task in Robotic-Assisted Minimally Invasive Surgery.

With robotic-assisted minimally invasive surgery (RAMIS), patients and surgeons benefit from a reduced incision size and dexterous instruments. However, current robotic surgery platforms lack haptic feedback, which is an essential element of safe operation. Moreover, teleportation control challenges make complex surgical tasks like suturing more time-consuming than those that use manual tools. This paper presents a new force-sensing instrument that semi-automates the suturing task and facilitates teleoperated robotic manipulation. In order to generate the ideal needle insertion trajectory and pass the needle through its curvature, the end-effector mechanism has a rotating degree of freedom. Impedance control was used to provide sensory information about needle-tissue interaction forces to the operator using an indirect force estimation approach based on data-based models. The operator's motion commands were then regulated using a hyperplanar virtual fixture (VF) designed to maintain the desired distance between the end-effector and tissue surface while avoiding unwanted contact. To construct the geometry of the VF, an optoelectronic sensor-based approach was developed. Based on the experimental investigation of the hyperplane VF methodology, improved needle-tissue interaction force, manipulation accuracy, and task completion times were demonstrated. Finally, experimental validation of the trained force estimation models and the perceived interaction forces by the user was conducted using online data, demonstrating the potential of the developed approach in improving task performance.

A Phase 1 Study of a Novel Bidirectional Perfusion Cannula in Patients Undergoing Femoral Cannulation for Cardiac Surgery.

OBJECTIVE: Leg ischemia is a serious complication of femoral artery cannulation. The primary aim of this study was to assess the safety and efficacy of a novel bidirectional femoral arterial cannula (Sorin Group USA, a wholly owned subsidiary of LivaNova PLC, Arvada, CO USA) that provides both antegrade and retrograde flow, in patients undergoing peripheral cannulation for cardiopulmonary bypass during cardiac surgery. METHODS: Patients undergoing routine cardiac surgery requiring femoral artery cannulation for cardiopulmonary bypass were identified preoperatively. Informed written consent was obtained in all cases. Bidirectional cannula insertion used either a surgical cut-down and wire through needle approach or a percutaneous technique. Flow in the superficial femoral artery was assessed using Doppler ultrasound after commencement of cardiopulmonary bypass. Lower limb perfusion was assessed using reflectance near-infrared spectroscopy to measure regional oxygen saturations in the cannulated limb during cardiopulmonary bypass. RESULTS: Fifteen patients (median age = 61.3 years, range = 26-79 years, 10 males, 5 females) underwent femoral arterial cannulation using the novel bidirectional femoral cannula between August 2016 and May 2017. Fourteen cannulae were inserted directly into the femoral artery via a surgical cut-down and wire through needle technique. One bidirectional cannula was inserted using a percutaneous insertion technique. Indications included minimally invasive mitral and aortic valve surgery, thoracic aortic aneurysm repair, and redo cardiac surgery. The median duration of cardiopulmonary bypass was 129 minutes (range = 53-228 minutes). The cannula was inserted and positioned without difficulty in 14 of 15 patients. Incorrect sizing and arterial spasm prevented correct cannula positioning in one patient. Antegrade flow in the superficial femoral artery was observed on Doppler ultrasound in 12 of 12 patients in which this was performed. Continuous stable distal perfusion was demonstrated in the cannulated limb in 14 of 15 patients. No procedural complications occurred in the immediate or convalescent postoperative period. CONCLUSIONS: This study demonstrates that in patients undergoing femoral arterial cannulation for cardiopulmonary bypass during cardiac surgery, the use of a novel bidirectional cannula is safe and easy to insert and provides stable distal perfusion of the cannulated limb. Use of the device should largely obviate the need to insert a separate downstream perfusion cannula or use other techniques to protect against lower limb ischemia. Further research on a larger scale and in different patient populations is now warranted.

Pressure and Flow Characteristics of a Novel Bidirectional Cannula for Cardiopulmonary Bypass.

OBJECTIVE: Femoral arterial cannulation is associated with a significant risk of lower limb ischemia. The aim of the study was to assess the pressure and flow in the femoral artery using a novel bidirectional femoral cannula in a sheep model of peripheral cardiopulmonary bypass. METHODS: Peripheral cardiopulmonary bypass was established using a multistage venous cannula inserted into the internal jugular vein and the bidirectional or a conventional arterial cannula into the femoral artery in seven adult ewes. Systemic and distal perfusion pressures and flow rates were measured during cardiopulmonary bypass with flow rates of 1, 2, 3, and 4 L/min. Lower limb venous oxygen saturation and lactate levels were also measured. RESULTS: A significantly higher blood flow in the lower limb using the bidirectional cannula was observed and compared with a conventional cannula at all flow rates (mean flow 115 mL/min vs 10 mL/min, P < 0.05). The mean distal perfusion pressure was also significantly higher in the bidirectional cannula group (86 mm Hg vs 45 mm Hg at 4 L/min of flow, P < 0.05). The bidirectional cannula was associated with higher venous oxygen saturations in the lower limb than in the conventional cannula group; however, lower limb lactate production was similar in the two groups. CONCLUSIONS: This in vivo data demonstrates superior distal flow and pressure characteristics of a novel bidirectional cannula compared with a conventional femoral cannula during peripheral cardiopulmonary bypass.

Novel Sternal Protection Device for Cardiac Surgery Via Median Sternotomy Incision.

OBJECTIVE: Sternal bleeding during cardiac surgery is currently controlled using bone wax or other chemical substances that may result in adverse effects and affect wound healing and recovery. The purpose of this study was to identify a safe, cost-effective, and easy-to-use technique to reduce sternal bleeding and sternal trauma during cardiac surgery. METHODS: After sternotomy, a sternal protection device was placed over each hemisternal section before insertion of the retractor and remained in situ until the end of surgery. Sternal bleeding and ease of use were assessed and recorded during surgery. Sternal trauma was assessed and recorded within 5 minutes of removal of the device, and overall satisfaction (Global Impression) and any intraoperative adverse events or device malfunction were reported at surgery completion. Patients were followed up 24 hours and 4 weeks after surgery. RESULTS: Twelve patients completed the study. Adverse events reported were not considered related to the device. No sternal trauma was identified in any patient. In 9 of 11 patients, sternal bleeding was reduced after insertion of the device. The device was generally considered easy to use, although some difficulty was encountered when used with the Internal Mammary Artery retractor. CONCLUSIONS: Our data suggest that the device is safe and able to reduce sternal bleeding during surgery using sternal retractors. We recommend further studies in a larger population of patients with a control group to evaluate the device's ability to reduce the morbidity associated with sternal bleeding and sternal trauma.

Sheathless transcatheter aortic valve implantation via the direct aortic approach.

Transcatheter aortic valve replacement (TAVR) has become an accepted alternate treatment modality to surgical aortic valve replacement in high surgical risk patients. There remains, however, a subset of patients in whom safe delivery of a TAVR device cannot be achieved by the femoral or subclavian routes. In such cases the direct aortic or transapical routes can be used though this still requires suitable anatomy. We present the first reported case of a direct aortic TAVR using a sheathless technique in order to provide sufficient distance to safely deliver the prosthesis.

Lung T-cell responses to nontypeable Haemophilus influenzae in patients with chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterized by pulmonary inflammation that persists after the cessation of smoking. T cells have a major role in driving inflammation in patients with COPD and are activated by specific antigens to produce mediators, such as cytokines. The antigens that activate lung T cells have not been clearly defined. Nontypeable Haemophilus influenzae (NTHi) is the dominant bacterium isolated from the lungs of patients with COPD. OBJECTIVE: We sought to measure the response of lung tissue T cells to stimulation with NTHi. METHODS: We obtained lung tissue from 69 subjects having lobectomies for lung cancer. Of the group, 39 subjects had COPD, and 30 without COPD were classified as control subjects. The lung tissue was dispersed into single-cell suspensions and stimulated with live NTHi. Cells were labeled with antibodies for 5 important inflammatory mediators in patients with COPD and analyzed by using flow cytometry. RESULTS: NTHi produced strong activation of both TH cells and cytotoxic T cells in the COPD cohort. The COPD cohort had significantly higher levels of cells producing TNF-α, IL-13, and IL-17 in both T-cell subsets. When control subjects were divided into those with and without a significant smoking history and compared with patients with COPD, there was a progressive increase in the numbers of T cells producing cytokines from nonsmoking control subjects to smoking control subjects to patients with COPD. CONCLUSION: NTHi activates lung T cells in patients with COPD. This proinflammatory profibrotic response might be a key cause of inflammation in patients with COPD and has implications for treatment.

Non-operative management of tube thoracostomy induced pulmonary artery injury.

Tube thoracostomy insertion is a common procedure in the management of air and fluid collections in the pleural space. Pulmonary artery injury is a rare but serious complication following intercostal catheterisation. This complication is usually managed surgically. We report a case of successful non-operative management of a pulmonary artery injury after tube thoracostomy.

Echocardiographic measurement of mitral intertrigonal distance is an adjunct to annuloplasty ring sizing.

BACKGROUND AND AIM OF THE STUDY: Annuloplasty sizing with standard valve sizers may be imprecise and difficult in minimally invasive procedures. It is hypothesized that a constant clinical conversion factor relates the echocardiographic aortic annulus diameter (AAD) and the intertrigonal distance (ITD) in patients with degenerative mitral regurgitation (MR). This may provide another method to size the annuloplasty ring required for mitral valve repair. METHODS: An observational study of 50 patients with degenerative MR undergoing robotic-assisted surgery was conducted. All patients underwent surgery between September 2005 and November 2007. The AAD at the base of the aortic leaflets was measured using intraoperative two-dimensional transesophageal echocardiography. The ITD was measured independently under direct vision during surgery. The echocardiographic ITD was then determined by dividing the AAD by 0.8, and the value for each patient compared to the corresponding surgical measurement. Agreement was assessed statistically using the Bland-Altman method. RESULTS: The limits of agreement were -3 mm (t = 2.010; 49 df; p = 0.05; 95% CI: -4 to -2 mm) to 3 mm (t = 2.010; 49 df; p = 0.05; 95% CI: 2 to 4 mm). In 86% of cases (43/50), the differences between the two methods was < or = 2 mm. CONCLUSION: In most cases of degenerative mitral valve disease the echocardiographic ITD measurement is clinically acceptable, and may serve as an adjunct to existing methods when sizing the annuloplasty ring required for repair.

Urgent and emergency coronary artery bypass grafting for acute coronary syndromes.

BACKGROUND: Urgent and emergency coronary artery bypass grafting may be associated with significant mortality and morbidity. We report our recent experience with this group of patients. METHODS: A retrospective analysis of 441 patients undergoing urgent and emergency surgery over a 3-year period was carried out. Multivariate analysis was used to identify subgroups of patients who were most at risk of death. RESULTS: The 30-day mortality was 3.3 and 16.3% in the urgent and emergency groups, respectively. Urgent surgery was associated with significantly shorter duration of ventilation (16 h vs 69 h) and stay at the intensive care unit (31 h vs 102 h). The incidence of pneumonia, pulmonary embolism, renal failure and neurological events were also less in the urgent group. The preoperative use of the intra-aortic balloon pump was low (0.8% in the urgent group and 4.8% in the emergency group). Multivariate analysis showed that patients over 70 years of age (odds ratio 3.2, 95% confidence interval 1.1-9.5) with left main stenosis (odds ratio 4.4, 95% confidence interval 1.5-12.4) complicated by cardiogenic shock (odds ratio 17.8, 95% confidence interval 5.2-61.1) were at highest risk of death. Patients transferred directly to theatre from cardiac catheter laboratory following failed percutaneous interventions were found to be most at risk. Mortality in this group was 29%, with 50% patients being in shock and 36% having left main stenosis. CONCLUSION: Satisfactory results have been obtained in urgent coronary artery bypass grafting, but acute coronary syndromes complicated by cardiogenic shock remain a high-risk group. Further studies are needed to define the optimal operative management in this group of patients.

Robotic cardiac surgery at Epworth hospital.

Epworth Hospital is the first in the southern hemisphere to acquire the da Vinci Robot to facilitate minimally invasive cardiac surgery. Applications for this new technology include mitral valve repair, atrial septal defect closure, single coronary artery bypass graft to coronary arteries on the front of the heart, ablative surgery for atrial fibrillation and insertion of epicardial pacemaker electrodes. A team of surgeons from the Epworth Hospital have trained at East Carolina University (ECU) Greenville, North Carolina, USA; including surgeons, anesthetists, perfusionist and nurses. Following this, during a week in March, a proctoring surgeon from the USA, Dr. Wiley Nifong, assisted the Epworth team with their initial seven operations, which all proceeded without incident. The initial operative times were longer than the standard surgery, although with additional experience, now totalling 24 patients in all, these times have shortened considerably. The experience to date is summarized as an Addendum to this manuscript.