Brian L. Davies

Resistance to Suppression by Dexamethasone of Plasma 11-O.H.C.S. Levels in Severe Depressive Illness

Use of the midnight dexamethasone suppression test showed that the plasma 11-hydroxycorticosteroid (11-O.H.C.S.) level did not undergo its normal reduction in 14 out of 27 patients with severe depression. Resistance to dexamethasone suppression correlated with the clinical rating of the severity of depression, while recovery from depression was associated with return of normal responsiveness to dexamethasone. The explanation of these findings is unknown.

The Probot--an active robot for prostate resection.

Abstract As men age, their prostates can enlarge, causing urinary difficulty. Surgery to correct this [transurethral resection of the prostate (TURP)] is a skilled and time-consuming operation requiring many repetitive motions of a cutter. A robot has been developed to perform these motions, relieving the surgeon of much of the burden of surgery. This robot has been tried both in the laboratory and later on human subjects and has proved itself capable of performing prostate resection. The Probot system consists of on-line imaging and three-dimensional prostate model construction, an appropriate surgeon-computer interface, a counterbalanced mounting frame and a computer controlled robot.

Active compliance in robotic surgery—the use of force control as a dynamic constraint:

Abstract Robotic surgery can be carried out automatically by using a robot to move the cutting tool under position control. However, although the surgeon can observe the procedure on a visual display and has the ability to stop the operation in an emergency, he has little direct contact with the task. An alternative approach is to involve the surgeon more directly, by his moving a robot using active force control. The robot is then used to allow motion in preprogrammed regions, by the surgeon back-driving the robot motors, while preventing motion in prohibited areas. This active constraint robot (or ACROBOT) is described in this paper applied to knee surgery, in which the knee bones are accurately machined to allow the fitting of prosthetic knee implants. The ACROBOT is, however, ideally suited to a range of surgical procedures, because it allows the surgeon to feel the forces exerted during cutting and take appropriate action. This ability to be in direct control, while being constrained to cut within a permitted region, enhances safety and makes the system more acceptable to the medical community. The system of programmable constraint also allows the ACROBOT to provide the traditional benefits of robot surgery, namely the ability to machine complex geometrical surfaces very accurately and to make repetitive motions tirelessly. The system also has a potential for minimally invasive procedures. In knee surgery, for example, the robot could operate through a small incision in the skin and excise a volume into which a small, specially designed, unicompartmental prosthesis could fit.

A review of medical robotics for minimally invasive soft tissue surgery

Abstract This paper provides an overview of recent trends and developments in medical robotics for minimally invasive soft tissue surgery, with a view to highlight some of the issues posed and solutions proposed in the literature. The paper includes a thorough review of the literature, which focuses on soft tissue surgical robots developed and published in the last five years (between 2004 and 2008) in indexed journals and conference proceedings. Only surgical systems were considered; imaging and diagnostic devices were excluded from the review. The systems included in this paper are classified according to the following surgical specialties: neurosurgery; eye surgery and ear, nose, and throat (ENT); general, thoracic, and cardiac surgery; gastrointestinal and colorectal surgery; and urologic surgery. The systems are also cross-classified according to their engineering design and robotics technology, which is included in tabular form at the end of the paper. The review concludes with an overview of the field, along with some statistical considerations about the size, geographical spread, and impact of medical robotics for soft tissue surgery today.

Active Constraints/Virtual Fixtures: A Survey

Active constraints, also known as virtual fixtures, are high-level control algorithms which can be used to assist a human in man-machine collaborative manipulation tasks. The active constraint controller monitors the robotic manipulator with respect to the environment and task, and anisotropically regulates the motion to provide assistance. The type of assistance offered by active constraints can vary, but they are typically used to either guide the user along a task-specific pathway or limit the user to within a “safe” region. There are several diverse methods described within the literature for applying active constraints, and these are surveyed within this paper. The active constraint research is described and compared using a simple generalized framework, which consists of three primary processes: 1) constraint definition, 2) constraint evaluation, and 3) constraint enforcement. All relevant research approaches for each of these processes, found using search terms associated to “virtual fixture,” “active constraint” and “motion constraint,” are presented.

Experiences with robotic systems for knee surgery

Robots have the potential to assist in orthopaedic surgery and improve the outcome of prosthetic implants. Robots have high positional accuracy, and so can achieve the geometrical precision necessary for implanting prostheses into the tibia and femur but poor tactile response, so are not good at assessing the forces required to apply to a cutter while resecting bone; while surgeons have a good tactile sense, and are able to sense changes in bone density, and adjust cutting forces to match. A system is described here that exploits the synergy between robot and surgeon. A force controlled pobot is used, guided from the end-effector by the surgeon. The robot exploits a software based motion constraint system to ensure that the surgeon cannot move a cutting device connected to the robot outside of a safe region, or resect more bone than is required. Thus, the surgeon retains his tactile sense of the bone, while the precision of the robot allows the bones to be cut accurately. Preliminary results are presented in this paper. More complete details of the robot and system performance will be presented at the symposium.

The case for MR-compatible robotics: a review of the state of the art

The numerous imaging capabilities of magnetic resonance imaging (MRI) coupled with its lack of ionizing radiation has made it a desirable modality for real‐time guidance of interventional procedures. The combination of these abilities with the advantages granted by robotic systems to perform accurate and precise positioning of tools has driven the recent development of MR‐compatible interventional and assistive devices.

The use of localizers, robots and synergistic devices in CAS

There are many roles for electromechanical devices in image guided surgery. One is to help a surgeon accurately follow a preoperative plan. Devices for this purpose may be localizers, robots4, or recently, synergistic systems in which surgeon and mechanism physically share control of the surgical tool. This paper discusses available technologies, and some emerging technologies, for guiding a surgical tool. Characteristics of each technology are discussed, and related to the needs which arise in surgical procedures. Three different approaches to synergistic systems, under study by the authors (PADyC, ACROBOT, and Cobots), are highlighted.

A Comparative Study of Four Depression Rating Scales

Comparisons were made between the overall scores on the Beck, Hamilton, Zung and a visual analogue rating scale in a group of depressed patients. The comparisons were made initially and at one, two and three weeks. Significant correlations between the global scores were found on these depression scales. The value of these scales in clinical research studies in depression is discussed with special mention of the value of the visual analogue scale.

Controlled trial of amitriptyline in general practice.

A controlled double-blind trial of amitriptyline at two dosage levels (75 and 150 mg/day), amylobarbitone (150 mg/day), and an inert substance for a period of four weeks was conducted on four matched groups of women attending their general practitioners and suffering from a depressive illness. Improvement at 7 and 28 days was noted on several measures of depression and anxiety in all treatment groups. Of these treatments amitriptyline 150 mg/day was the most consistent in relieving depression and anxiety. Troublesome side effects were equally distributed among the four treatments.